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Sample records for collision mac protocol

  1. Design and Analysis of an Asynchronous Zero Collision MAC Protocol

    CERN Document Server

    Lee, Jiwoong

    2008-01-01

    This paper proposes and analyzes a distributed MAC protocol that achieves zero collision with no control message exchange nor synchronization. ZC (ZeroCollision) is neither reservation-based nor dynamic TDMA; the protocol supports variable-length packets and does not lose efficiency when some of the stations do not transmit. At the same time, ZC is not a CSMA; in its steady state, it is completely collision-free. The stations transmit repeatedly in a round-robin order once the convergence state is reached. If some stations skip their turn, their transmissions are replaced by idle $20 \\mu$-second mini-slots that enable the other stations to keep track of their order. Because of its short medium access delay and its efficiency, the protocol supports both real-time and elastic applications. The protocol allows for nodes leaving and joining the network; it can allocate more throughput to specific nodes (such as an access point). The protocol is robust against carrier sensing errors or clock drift. While collision...

  2. Intelligent Local Avoided Collision (iLAC) MAC Protocol for Very High Speed Wireless Network

    Science.gov (United States)

    Hieu, Dinh Chi; Masuda, Akeo; Rabarijaona, Verotiana Hanitriniala; Shimamoto, Shigeru

    Future wireless communication systems aim at very high data rates. As the medium access control (MAC) protocol plays the central role in determining the overall performance of the wireless system, designing a suitable MAC protocol is critical to fully exploit the benefit of high speed transmission that the physical layer (PHY) offers. In the latest 802.11n standard [2], the problem of long overhead has been addressed adequately but the issue of excessive colliding transmissions, especially in congested situation, remains untouched. The procedure of setting the backoff value is the heart of the 802.11 distributed coordination function (DCF) to avoid collision in which each station makes its own decision on how to avoid collision in the next transmission. However, collision avoidance is a problem that can not be solved by a single station. In this paper, we introduce a new MAC protocol called Intelligent Local Avoided Collision (iLAC) that redefines individual rationality in choosing the backoff counter value to avoid a colliding transmission. The distinguishing feature of iLAC is that it fundamentally changes this decision making process from collision avoidance to collaborative collision prevention. As a result, stations can avoid colliding transmissions with much greater precision. Analytical solution confirms the validity of this proposal and simulation results show that the proposed algorithm outperforms the conventional algorithms by a large margin.

  3. Altruistic Backoff: Collision Avoidance for Receiver-Initiated MAC Protocols for Wireless Sensor Networks

    DEFF Research Database (Denmark)

    Fafoutis, Xenofon; Orfanidis, Charalampos; Dragoni, Nicola

    2014-01-01

    In receiver-initiated medium access control (MAC) protocols for wireless sensor networks, communication is initiated by the receiver node which transmits beacons indicating its availability to receive data. In the case of multiple senders having traffic for a given receiver, such beacons form...... points where collisions are likely to happen. In this paper, we present altruistic backoff (AB), a novel collision avoidance mechanism that aims to avoid collisions before the transmission of a beacon. As a result of an early backoff, senders spend less time in idle listening waiting for a beacon, thus...

  4. Blind Cognitive MAC Protocols

    CERN Document Server

    Mehanna, Omar; Gamal, Hesham El

    2008-01-01

    We consider the design of cognitive Medium Access Control (MAC) protocols enabling an unlicensed (secondary) transmitter-receiver pair to communicate over the idle periods of a set of licensed channels, i.e., the primary network. The objective is to maximize data throughput while maintaining the synchronization between secondary users and avoiding interference with licensed (primary) users. No statistical information about the primary traffic is assumed to be available a-priori to the secondary user. We investigate two distinct sensing scenarios. In the first, the secondary transmitter is capable of sensing all the primary channels, whereas it senses one channel only in the second scenario. In both cases, we propose MAC protocols that efficiently learn the statistics of the primary traffic online. Our simulation results demonstrate that the proposed blind protocols asymptotically achieve the throughput obtained when prior knowledge of primary traffic statistics is available.

  5. The MAC framework: redefining MAC protocols for wireless sensor networks

    NARCIS (Netherlands)

    Parker, T.; Halkes, G.; Bezemer, M.; Langendoen, K.

    2010-01-01

    Most current WSN MAC protocol implementations have multiple tasks to perform—deciding on correct timing, sending of packets, sending of acknowledgements, etc. However, as much of this is common to all MAC protocols, there is duplication of functionality, which leads to larger MAC protocol code size

  6. The MAC framework: redefining MAC protocols for wireless sensor networks

    NARCIS (Netherlands)

    Parker, T.; Halkes, G.; Bezemer, M.; Langendoen, K.

    2010-01-01

    Most current WSN MAC protocol implementations have multiple tasks to perform—deciding on correct timing, sending of packets, sending of acknowledgements, etc. However, as much of this is common to all MAC protocols, there is duplication of functionality, which leads to larger MAC protocol code size

  7. Low duty cycle and low collision asynchronous MAC protocol for wireless sensor network%低占空比、低碰撞的异步无线传感器网络MAC协议

    Institute of Scientific and Technical Information of China (English)

    李哲涛; 朱更明; 王志强; 裴廷睿; 潘高峰

    2013-01-01

    提高信道监听质量是降低能量消耗和提高通信效率的有效方法。提出了一种低占空比、低碰撞的PB-MAC(predict-base MAC)协议。通过发送节点精确预测接收节点的唤醒时间,降低占空比;采用基于预测的重建连接机制和数据重传机制,有效地避免碰撞和实现高效重传。OMNet++仿真实验结果表明:在50节点随机网络中,PB-MAC的平均占空比、发送消息耗能和平均碰撞次数分别比RI-MAC少68.60%、24.75%、68.05%,比X-MAC少64.39%、64.05%、70.54%。同时,在网格网络中PB-MAC的性能也优于RI-MAC和X-MAC。%Improving the quality of channel listening is an effective way to reduce energy consumption and improve communication efficiency. PB-MAC(predict-base MAC), a novel low duty cycle and low collision asynchronous MAC protocol was presented. PB-MAC lowers sensor duty cycle by enabling senders to predict receiver wakeup times. An ef-ficient prediction-based reconnection and retransmission mechanism was introduced to achieve low collisions and high efficiency retransmission. Comparison of PB-MAC on OMNet++with RI-MAC and X-MAC was evaluated. Evaluated on scenarios with 50 random disposed nodes, the average duty cycle, consumed energy and average collisions for PB-MAC is 68.60%, 24.75%and 68.05%less than those of RI-MAC and 64.39%, 64.05%and 70.54%less than those of X-MAC respectively. In grid network, PB-MAC also outperforms RI-MAC and X-MAC protocols.

  8. Mac protocols for cyber-physical systems

    CERN Document Server

    Xia, Feng

    2015-01-01

    This book provides a literature review of various wireless MAC protocols and techniques for achieving real-time and reliable communications in the context of cyber-physical systems (CPS). The evaluation analysis of IEEE 802.15.4 for CPS therein will give insights into configuration and optimization of critical design parameters of MAC protocols. In addition, this book also presents the design and evaluation of an adaptive MAC protocol for medical CPS, which exemplifies how to facilitate real-time and reliable communications in CPS by exploiting IEEE 802.15.4 based MAC protocols. This book wil

  9. Wireless sensors networks MAC protocols analysis

    CERN Document Server

    Chaari, Lamia

    2010-01-01

    Wireless sensors networks performance are strictly related to the medium access mechanism. An effective one, require non-conventional paradigms for protocol design due to several constraints. An adequate equilibrium between communication improvement and data processing capabilities must be accomplished. To achieve low power operation, several MAC protocols already proposed for WSN. The aim of this paper is to survey and to analyze the most energy efficient MAC protocol in order to categorize them and to compare their performances. Furthermore we have implemented some of WSN MAC protocol under OMNET++ with the purpose to evaluate their performances.

  10. Collision Free MAC Protocol for Multi-Hop Wireless Networks%面向多跳无线网络的无冲突MAC协议

    Institute of Scientific and Technical Information of China (English)

    张克旺; 张德运; 杜君

    2009-01-01

    Collision rate increases significantly with the appearance of hidden nodes in multi-hop wireless network, which results in unsuccessful transmissions and leads to performance degradation of the network. The RTS/CTS handshakes of 802.11DCF can not eliminate hidden nodes, and the situation becomes worse when the nodes are equipped with higher speed wireless devices, which require higher signal to interference and noise ratio (SINR) for successful reception. This paper analyzes the prevalence of hidden nodes in multi-hop wireless network and proposes an MAC protocol named double channel collision free media access protocol-DCCFMA to solve the hidden nodes problem. DCCFMA is a dual channel MAC (media access control) protocol, receiver adjusts the transmitting power of the control channel according to the signal power receiver from the transmitter so as to cover all hidden nodes around the receiver. Simulation results show that DCCFMA solves hidden nodes problem better than RTS/CTS (ready-to-send/clear-to-send) handshakes and achieves 24% additional network throughput as compared to that of 802.11 DCF.%多跳无线网络中隐藏节点导致节点之间的冲突频繁、数据重传率高、网络吞吐量下降.而802.11 DCF中的RTS/CTS(ready-to-send/clear-to-send)机制不能有效地防止隐藏节点,特别是随着网络中节点通信速率的提高,由于节点的信噪比要求也相应提高,接收节点受到更大范围内隐藏节点的干涉,RTS/CTS机制防止隐藏节点的效率急剧降低.首先,在考虑网络积累干涉以及环境噪音的情况下分析了多跳无线网络中的隐藏节点问题.然后,提出一种双信道无冲突MAC(media access control)协议DCCFMA(double channel collision free media access).DCCFMA协议采用双信道结构,接收节点根据数据信道中发送节点的信号强度动态调节控制信道的发射功率,以完全覆盖接收节点周围所有的隐藏节点,保证接收节点在

  11. SR-MAC: A Low Latency MAC Protocol for Multi-Packet Transmissions in Wireless Sensor Networks

    Institute of Scientific and Technical Information of China (English)

    Hong-Wei Tang; Jian-Nong Cao; Xue-Feng Liu; Cai-Xia Sun

    2013-01-01

    Event detection is one of the major applications of wireless sensor networks (WSNs).Most of existing medium access control (MAC) protocols are mainly optimized for the situation under which an event only generates one packet on a single sensor node.When an event generates multiple packets on a single node,the performance of these MAC protocols degrades rapidly.In this paper,we present a new synchronous duty-cycle MAC protocol called SR-MAC for the event detection applications in which multiple packets are generated on a single node.SR-MAC introduces a new scheduling mechanism that reserves few time slots during the SLEEP period for the nodes to transmit multiple packets.By this approach,SR-MAC can schedule multiple packets generated by an event on a single node to be forwarded over multiple hops in one operational cycle without collision.We use event delivery latency (EDL) and event delivery ratio (EDR) to measure the event detection capability of the SR-MAC protocol.Through detailed ns-2 simulation,the results show that SR-MAC can achieve lower EDL,higher EDR and higher network throughput with guaranteed energy efficiency compared with R-MAC,DW-MAC and PR-MAC.

  12. Comparison of CSMA based MAC protocols of wireless sensor networks

    CERN Document Server

    singh, Himanshu

    2012-01-01

    Energy conservation has been an important area of interest in Wireless Sensor networks (WSNs). Medium Access Control (MAC) protocols play an important role in energy conservation. In this paper, we describe CSMA based MAC protocols for WSN and analyze the simulation results of these protocols. We implemented S-MAC, T-MAC, B-MAC, B-MAC+, X-MAC, DMAC and Wise-MAC in TOSSIM, a simulator which unlike other simulators simulates the same code running on real hardware. Previous surveys mainly focused on the classification of MAC protocols according to the techniques being used or problem dealt with and presented a theoretical evaluation of protocols. This paper presents the comparative study of CSMA based protocols for WSNs, showing which MAC protocol is suitable in a particular environment and supports the arguments with the simulation results. The comparative study can be used to find the best suited MAC protocol for wireless sensor networks in different environments.

  13. Low power listening MAC protocol with collision avoidance and traffic adaption%带冲突避免和流量自适应的低功耗侦听MAC协议

    Institute of Scientific and Technical Information of China (English)

    彭昌睿; 黄宏光

    2013-01-01

    为提升无线传感器网络在能耗、时延以及动态适应负载方面的综合性能,对几种典型MAC协议进行了分析,提出了一种带冲突避免和流量自适应的LCT-MAC协议.在该协议中,长前导码被划分为多个小前导码,并嵌入目的节点地址信息,避免了串音;节点可以根据网络流量调整睡眠周期,减少了时延;在重负载时,节点能基于优先级信息选择退避时长,避免冲突.仿真结果表明,与S-MAC协议和LPL协议相比,LCT-MAC协议降低了传输时延,并减少了全网能耗和数据包碰撞次数,具有优良的综合性能.%To improve performance of wireless sensor networks in terms of energy consumption,network latency and traffic adaption,this paper proposed LCT-MAC with collision avoidance and traffic adaption through analyzing some classic MAC protocols.This protocol divided the long preamble into lots of small ones embedded with destination address to avoid crosstalk,and adjusted nodes sleep cycle according to traffic loads dynamically,and chose proper backoff time to avoid message collisions on the basis of nodes' priority.Simulations demonstrate that LCT-MAC is superior to both S-MAC and LPL in aspects of network latency,energy consumption as well as message collision,and has a good performance.

  14. Power Saving MAC Protocols for WSNs and Optimization of S-MAC Protocol

    Directory of Open Access Journals (Sweden)

    Simarpreet Kaur

    2012-11-01

    Full Text Available Low power MAC protocols have received a lot of consideration in the last few years because of their influence on the lifetime of wireless sensor networks. Since, sensors typically operate on batteries, replacement of which is often difficult. A lot of work has been done to minimize the energy expenditure and prolong the sensor lifetime through energy efficient designs, across layers. Meanwhile, the sensor network should be able to maintain a certain throughput in order to fulfill the QoS requirements of the end user, and to ensure the constancy of the network. This paper introduces different types of MAC protocols used for WSNs and proposes S‐MAC, a Medium‐Access Control protocol designed for Wireless Sensor Networks. S‐MAC uses a few innovative techniques to reduce energy consumption and support selfconfiguration. A new protocol is suggested to improve the energy efficiency, latency and throughput of existing MAC protocol for WSNs. A modification of the protocol is then proposed to eliminate the need for some nodes to stay awake longer than the other nodes which improves the energy efficiency, latency and throughput and hence increases the life span of a wireless sensor network.

  15. On the Selection of MAC Optimised Routing Protocol for VANET

    Directory of Open Access Journals (Sweden)

    Kanu Priya

    2017-02-01

    Full Text Available In today‘s era of modernization, the concept of smart vehicles, smart cities and automated vehicles is trending day by day. VANET (Vehicular Adhoc Network has also been emerging as a potential applicant to enable these smart applications. Though VANET is very much similar to MANET (Mobile Adhoc Network but VANET has more severe challenges as compared to MANET due to hostile channel conditions and high degree of mobility. So lot of work related to MAC and Network Layer need attention from the network designers. In this paper MAC Layer has been optimised in terms of Queue Size by using QoS Parameters namely Packet Collision Rate, Packet Drop Rate, Throughput Rate and Broadcast Rate. In doing so, simulative investigations have been done to find out optimum queue size. For this purpose various routing protocols namely DSDV, AODV, ADV and GOD have been considered and optimum queue length for each of these have been obtained. Further the most efficient routing protocol has also been identified. Moreover this paper also compares the performance of most efficient Routing Protocols selected in terms of QoS parameters for different MAC Interfaces.

  16. Energy-efficient MAC protocols for Wireless Sensor Networks

    Institute of Scientific and Technical Information of China (English)

    Li De-liang; Peng Fei

    2009-01-01

    Designing energy-efficient Medium Access Control (MAC) protocols has a significant influence on the energy performance of wireless sensor network (WSN). In this paper we present a survey of the recent typical MAC protocols regarding energy efficiency for WSN. According to channel access policies, we classify these protocols into four categories: contention-based, TDMA-based, hybrid, and cross layer protocols, in which the advantages and disadvantages in each class of MAC protocols are discussed. Finally, we point out open research issues that need to carry on to achieve high energy efficiency for the design of MAC protocols in WSN.

  17. CR-MAC: A multichannel MAC protocol for cognitive radio ad hoc networks

    CERN Document Server

    Kamruzzaman, S M

    2010-01-01

    This paper proposes a cross-layer based cognitive radio multichannel medium access control (MAC) protocol with TDMA, which integrate the spectrum sensing at physical (PHY) layer and the packet scheduling at MAC layer, for the ad hoc wireless networks. The IEEE 802.11 standard allows for the use of multiple channels available at the PHY layer, but its MAC protocol is designed only for a single channel. A single channel MAC protocol does not work well in a multichannel environment, because of the multichannel hidden terminal problem. Our proposed protocol enables secondary users (SUs) to utilize multiple channels by switching channels dynamically, thus increasing network throughput. In our proposed protocol, each SU is equipped with only one spectrum agile transceiver, but solves the multichannel hidden terminal problem using temporal synchronization. The proposed cognitive radio MAC (CR-MAC) protocol allows SUs to identify and use the unused frequency spectrum in a way that constrains the level of interference...

  18. Performance Analysis of MAC Layer Protocols in Wireless Sensor Network

    Directory of Open Access Journals (Sweden)

    Hameeza Ahmed

    2014-10-01

    Full Text Available Media Access Control (MAC layer protocols have a critical role in making a typical Wireless Sensor Network (WSN more reliable and efficient. Choice of MAC layer protocol and other factors including number of nodes, mobility, traffic rate and playground size dictates the performance of a particular WSN. In this paper, the performance of an experimental WSN is evaluated using different MAC layer protocols. In this experiment, a WSN is created using OMNeT++ MiXiM network simulator and its performance in terms of packet delivery ratio and mean latency is evaluated. The simulation results show that IEEE 802.11 MAC layer protocol performs better than CSMA, B-MAC and IEEE 802.15.4 MAC layer protocols. In the considered scenario, IEEE 802.15.4 is ranked second in performance, followed by CSMA and B-MAC.

  19. VLA-MAC: A Variable Load Adaptive MAC Protocol for Wireless Sensor Networks

    Science.gov (United States)

    Yao, Guoliang; Liu, Hao; Chen, Hao; Shi, Longxin

    This letter presents VLA-MAC, a novel adaptive MAC protocol for wireless sensor networks that can achieve high energy efficiency and low latency in variable load conditions. In VLA-MAC, traffic load is measured online and utilized for adaptive adjustment. VLA-MAC transmits packets via a burst style to alleviate packets accumulation problem and achieve low latency in high load condition. Furthermore, it also saves obvious energy by removing unnecessary listen period in low load condition. Unlike current approach, VLA-MAC does not need to adjust duty-cycle according to load online. Simulation results based on ns-2 show the performance improvements of our protocol.

  20. H-MAC: A Hybrid MAC Protocol for Wireless Sensor Networks

    CERN Document Server

    Mehta, S; 10.5121/ijcnc.2010.2208

    2010-01-01

    In this paper, we propose a hybrid medium access control protocol (H-MAC) for wireless sensor networks. It is based on the IEEE 802.11's power saving mechanism (PSM) and slotted aloha, and utilizes multiple slots dynamically to improve performance. Existing MAC protocols for sensor networks reduce energy consumptions by introducing variation in an active/sleep mechanism. But they may not provide energy efficiency in varying traffic conditions as well as they did not address Quality of Service (QoS) issues. H-MAC, the propose MAC protocol maintains energy efficiency as well as QoS issues like latency, throughput, and channel utilization. Our numerical results show that H-MAC has significant improvements in QoS parameters than the existing MAC protocols for sensor networks while consuming comparable amount of energy.

  1. RMAC: A Reliable MAC Protocol Supporting Multicast for Wireless Ad Hoc Networks

    Institute of Scientific and Technical Information of China (English)

    Wei-Sheng Si; Cheng-Zhi Li

    2005-01-01

    This paper presents a new reliable MAC protocol called "RMAC" supporting reliable multicast for wireless ad hoc networks. By utilizing the busy tones to realize the multicast reliability, RMAC has three novelties: (1) it uses a variablelength control frame to stipulate an order for the receivers to respond, thus solving the feedback collision problem; (2) it extends the usage of busy tone for preventing data frame collisions into the multicast scenario; and (3) it introduces a new usage of busy tone for acknowledging data frames positively. In addition, RMAC is generalized into a comprehensive MAC protocol that provides both reliable and unreliable services for all the three modes of communications: unicast, multicast,and broadcast, making it capable of supporting various upper-layer protocols. The evaluation shows that RMAC achieves high reliability with very limited overhead. RMAC is also compared with other reliable MAC protocols, showing that RMAC not only provides higher reliability but also involves lower cost.

  2. Performance of a Wireless Sensor Network MAC Protocol with a Variable Sleep Interval

    Directory of Open Access Journals (Sweden)

    M.K. Kirubakaran

    2014-02-01

    Full Text Available A MAC protocol specifies how nodes in a sensor network access a shared communication channel. Medium access control protocols for wireless sensor networks are almost always designed to be energy efficient. Desired properties of such MAC protocol are: it should be distributed and contention-free. This study addresses low power MAC protocols utilize energy in efficient manner in wireless sensor networks. We are interested in the trade-off between power consumption and transmission delay, focusing on low traffic in EM-MAC. In EM-MAC, a significant proportion of the nodes may have to stay awake much longer than envisaged. We describe RRMAC protocol (Receiver-Reservation MAC protocol, a new protocol for the Collision avoidance and energy loss due to retransmissions and increase the life span of a wireless sensor networks. This study concludes with the result of simulation studies which indicate that the use of the proposed RRMAC protocol is expected to increase the life time of wireless sensor networks significantly.

  3. An Energy-Efficient, Application-Oriented Control Algorithm for MAC Protocols in WSN

    Science.gov (United States)

    Li, Deliang; Peng, Fei; Qian, Depei

    Energy efficiency has been a main concern in wireless sensor networks where Medium Access Control (MAC) protocol plays an important role. However, current MAC protocols designed for energy saving have seldom considered multiple applications coexisting in WSN with variation of traffic load dynamics and different QoS requirements. In this paper, we propose an adaptive control algorithm at MAC layer to promote energy efficiency. We focus on the tradeoff relation between collisions and control overhead as a reflection of traffic load and propose to balance the tradeoff under the constraints of QoS options. We integrate the algorithm into S-MAC and verify it through NS-2 platform. The results demonstrate the algorithm achieves observable improvement in energy performance while meeting QoS requirement for different coexisting applications in comparison with S-MAC.

  4. Multi-channel MAC Protocol in Cognitive Radio Networks

    Directory of Open Access Journals (Sweden)

    Yongli Sun

    2013-11-01

    Full Text Available Since cognitive wireless network (CRN has the characteristic of secondary use, it can enable the device to dynamically access available spectrum without interference to primary users (PUs, which can effectively alleviate contradiction between the lack of spectrum resources and the growing demand for wireless access. However, Medium Access Control (MAC protocol as CRN core components, can achieve competition access of the licensed spectrum and coordination control, which will maximize spectrum utilization efficiency and network throughput. The contribution of this survey is threefold. First, we analyze the characteristics of the existed multi- channel MAC protocol in CRN; Second, according to the different ways of spectrum access in CRNs, the multi-channel MAC protocols are classified into time-slotted based MAC protocol, control channel based MAC protocol and hybrid MAC protocol, and the paper emphatically analyzed the advantages and disadvantages of these multi-channel MAC protocols; Finally, the paper explores the difficulties and the challenges of multi-channel MAC protocols design in cognitive wireless network.

  5. SA-MAC:Self-Stabilizing Adaptive MAC Protocol for Wireless Sensor Networks

    Institute of Scientific and Technical Information of China (English)

    波澄; 韩君泽; 李向阳; 王昱; 肖波

    2014-01-01

    A common method of prolonging the lifetime of wireless sensor networks is to use low power duty cycling protocol. Existing protocols consist of two categories: sender-initiated and receiver-initiated. In this paper, we present SA-MAC, a self-stabilizing adaptive MAC protocol for wireless sensor networks. SA-MAC dynamically adjusts the transmission time-slot, waking up time-slot, and packet detection pattern according to current network working condition, such as packet length and wake-up patterns of neighboring nodes. In the long run, every sensor node will find its own transmission phase so that the network will enter a stable stage when the network load and qualities are static. We conduct extensive experiments to evaluate the energy consumption, packet reception rate of SA-MAC in real sensor networking systems. Our results indicate that SA-MAC outperforms other existing protocols.

  6. AH-MAC: Adaptive Hierarchical MAC Protocol for Low-Rate Wireless Sensor Network Applications

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    Adnan Ismail Al-Sulaifanie

    2017-01-01

    Full Text Available This paper proposes an adaptive hierarchical MAC protocol (AH-MAC with cross-layer optimization for low-rate and large-scale wireless sensor networks. The main goal of the proposed protocol is to combine the strengths of LEACH and IEEE 802.15.4 while offsetting their weaknesses. The predetermined cluster heads are supported with an energy harvesting circuit, while the normal nodes are battery-operated. To prolong the network’s operational lifetime, the proposed protocol transfers most of the network’s activities to the cluster heads while minimizing the node’s activity. Some of the main features of this protocol include energy efficiency, self-configurability, scalability, and self-healing. The simulation results showed great improvement of the AH-MAC over LEACH protocol in terms of energy consumption and throughput. AH-MAC consumes eight times less energy while improving throughput via acknowledgment support.

  7. A Priority-Based Adaptive MAC Protocol for Wireless Body Area Networks

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    Sabin Bhandari

    2016-03-01

    Full Text Available In wireless body area networks (WBANs, various sensors and actuators are placed on/inside the human body and connected wirelessly. WBANs have specific requirements for healthcare and medical applications, hence, standard protocols like the IEEE 802.15.4 cannot fulfill all the requirements. Consequently, many medium access control (MAC protocols, mostly derived from the IEEE 802.15.4 superframe structure, have been studied. Nevertheless, they do not support a differentiated quality of service (QoS for the various forms of traffic coexisting in a WBAN. In particular, a QoS-aware MAC protocol is essential for WBANs operating in the unlicensed Industrial, Scientific, and Medical (ISM bands, because different wireless services like Bluetooth, WiFi, and Zigbee may coexist there and cause severe interference. In this paper, we propose a priority-based adaptive MAC (PA-MAC protocol for WBANs in unlicensed bands, which allocates time slots dynamically, based on the traffic priority. Further, multiple channels are effectively utilized to reduce access delays in a WBAN, in the presence of coexisting systems. Our performance evaluation results show that the proposed PA-MAC outperforms the IEEE 802.15.4 MAC and the conventional priority-based MAC in terms of the average transmission time, throughput, energy consumption, and data collision ratio.

  8. A Priority-Based Adaptive MAC Protocol for Wireless Body Area Networks.

    Science.gov (United States)

    Bhandari, Sabin; Moh, Sangman

    2016-03-18

    In wireless body area networks (WBANs), various sensors and actuators are placed on/inside the human body and connected wirelessly. WBANs have specific requirements for healthcare and medical applications, hence, standard protocols like the IEEE 802.15.4 cannot fulfill all the requirements. Consequently, many medium access control (MAC) protocols, mostly derived from the IEEE 802.15.4 superframe structure, have been studied. Nevertheless, they do not support a differentiated quality of service (QoS) for the various forms of traffic coexisting in a WBAN. In particular, a QoS-aware MAC protocol is essential for WBANs operating in the unlicensed Industrial, Scientific, and Medical (ISM) bands, because different wireless services like Bluetooth, WiFi, and Zigbee may coexist there and cause severe interference. In this paper, we propose a priority-based adaptive MAC (PA-MAC) protocol for WBANs in unlicensed bands, which allocates time slots dynamically, based on the traffic priority. Further, multiple channels are effectively utilized to reduce access delays in a WBAN, in the presence of coexisting systems. Our performance evaluation results show that the proposed PA-MAC outperforms the IEEE 802.15.4 MAC and the conventional priority-based MAC in terms of the average transmission time, throughput, energy consumption, and data collision ratio.

  9. MAC2: A Multi-Hop Adaptive MAC Protocol with Packet Concatenation for Wireless Sensor Networks

    Science.gov (United States)

    Nguyen, Kien; Meis, Ulrich; Ji, Yusheng

    Wireless sensor network MAC protocols switch radios off periodically, employing the so-called duty cycle mechanism, in order to conserve battery power that would otherwise be wasted by energy-costly idle listening. In order to minimize the various negative side-effects of the original scheme, especially on latency and throughput, various improvements have been proposed. In this paper, we introduce a new MAC protocol called MAC2(Multi-hop Adaptive with packet Concatenation-MAC) which combines three promising techniques into one protocol. Firstly, the idea to forward packets over multiple hops within one operational cycle as initially introduced in RMAC. Secondly, an adaptive method that adjusts the listening period according to traffic load minimizing idle listening. Thirdly, a packet concatenation scheme that not only increases throughput but also reduces power consumption that would otherwise be incurred by additional control packets. Furthermore, MAC2 incorporates the idea of scheduling data transmissions with minimum latency, thereby performing packet concatenation together with the multi-hop transmission mechanism in a most efficient way. We evaluated MAC2 using the prominent network simulator ns-2 and the results show that our protocol can outperform DW-MAC — a state of the art protocol both in terms of energy efficiency and throughput.

  10. CR-MAC: A Multichannel MAC Protocol for Cognitive Radio AD HOC Networks

    Directory of Open Access Journals (Sweden)

    S. M. Kamruzzaman

    2010-09-01

    Full Text Available This paper proposes a cross-layer based cognitive radio multichannel medium access control (MACprotocol with TDMA, which integrate the spectrum sensing at physical (PHY layer and the packetscheduling at MAC layer, for the ad hoc wireless networks. The IEEE 802.11 standard allows for the useof multiple channels available at the PHY layer, but its MAC protocol is designed only for a singlechannel. A single channel MAC protocol does not work well in a multichannel environment, because ofthe multichannel hidden terminal problem. Our proposed protocol enables secondary users (SUs toutilize multiple channels by switching channels dynamically, thus increasing network throughput. In ourproposed protocol, each SU is equipped with only one spectrum agile transceiver, but solves themultichannel hidden terminal problem using temporal synchronization. The proposed cognitive radioMAC (CR-MAC protocol allows SUs to identify and use the unused frequency spectrum in a way thatconstrains the level of interference to the primary users (PUs. Our scheme improves network throughputsignificantly, especially when the network is highly congested. The simulation results show that ourproposed CR-MAC protocol successfully exploits multiple channels and significantly improves networkperformance by using the licensed spectrum band opportunistically and protects PUs from interference,even in hidden terminal situations.

  11. A Sensing Error Aware MAC Protocol for Cognitive Radio Networks

    CERN Document Server

    Hu, Donglin

    2011-01-01

    Cognitive radios (CR) are intelligent radio devices that can sense the radio environment and adapt to changes in the radio environment. Spectrum sensing and spectrum access are the two key CR functions. In this paper, we present a spectrum sensing error aware MAC protocol for a CR network collocated with multiple primary networks. We explicitly consider both types of sensing errors in the CR MAC design, since such errors are inevitable for practical spectrum sensors and more important, such errors could have significant impact on the performance of the CR MAC protocol. Two spectrum sensing polices are presented, with which secondary users collaboratively sense the licensed channels. The sensing policies are then incorporated into p-Persistent CSMA to coordinate opportunistic spectrum access for CR network users. We present an analysis of the interference and throughput performance of the proposed CR MAC, and find the analysis highly accurate in our simulation studies. The proposed sensing error aware CR MAC p...

  12. Synthesizing Existing CSMA and TDMA Based MAC Protocols for VANETs.

    Science.gov (United States)

    Huang, Jiawei; Li, Qi; Zhong, Shaohua; Liu, Lianhai; Zhong, Ping; Wang, Jianxin; Ye, Jin

    2017-02-10

    Many Carrier Sense Multiple Access (CSMA) and Time Division Multiple Access (TDMA) based medium access control (MAC) protocols for vehicular ad hoc networks (VANETs) have been proposed recently. Contrary to the common perception that they are competitors, we argue that the underlying strategies used in these MAC protocols are complementary. Based on this insight, we design CTMAC, a MAC protocol that synthesizes existing strategies; namely, random accessing channel (used in CSMA-style protocols) and arbitral reserving channel (used in TDMA-based protocols). CTMAC swiftly changes its strategy according to the vehicle density, and its performance is better than the state-of-the-art protocols. We evaluate CTMAC using at-scale simulations. Our results show that CTMAC reduces the channel completion time and increases the network goodput by 45% for a wide range of application workloads and network settings.

  13. Cooperative energy harvesting-adaptive MAC protocol for WBANs.

    Science.gov (United States)

    Esteves, Volker; Antonopoulos, Angelos; Kartsakli, Elli; Puig-Vidal, Manel; Miribel-Català, Pere; Verikoukis, Christos

    2015-05-28

    In this paper, we introduce a cooperative medium access control (MAC) protocol, named cooperative energy harvesting (CEH)-MAC, that adapts its operation to the energy harvesting (EH) conditions in wireless body area networks (WBANs). In particular, the proposed protocol exploits the EH information in order to set an idle time that allows the relay nodes to charge their batteries and complete the cooperation phase successfully. Extensive simulations have shown that CEH-MAC significantly improves the network performance in terms of throughput, delay and energy efficiency compared to the cooperative operation of the baseline IEEE 802.15.6 standard.

  14. A hybrid path-oriented code assignment CDMA-based MAC protocol for underwater acoustic sensor networks.

    Science.gov (United States)

    Chen, Huifang; Fan, Guangyu; Xie, Lei; Cui, Jun-Hong

    2013-11-04

    Due to the characteristics of underwater acoustic channel, media access control (MAC) protocols designed for underwater acoustic sensor networks (UWASNs) are quite different from those for terrestrial wireless sensor networks. Moreover, in a sink-oriented network with event information generation in a sensor field and message forwarding to the sink hop-by-hop, the sensors near the sink have to transmit more packets than those far from the sink, and then a funneling effect occurs, which leads to packet congestion, collisions and losses, especially in UWASNs with long propagation delays. An improved CDMA-based MAC protocol, named path-oriented code assignment (POCA) CDMA MAC (POCA-CDMA-MAC), is proposed for UWASNs in this paper. In the proposed MAC protocol, both the round-robin method and CDMA technology are adopted to make the sink receive packets from multiple paths simultaneously. Since the number of paths for information gathering is much less than that of nodes, the length of the spreading code used in the POCA-CDMA-MAC protocol is shorter greatly than that used in the CDMA-based protocols with transmitter-oriented code assignment (TOCA) or receiver-oriented code assignment (ROCA). Simulation results show that the proposed POCA-CDMA-MAC protocol achieves a higher network throughput and a lower end-to-end delay compared to other CDMA-based MAC protocols.

  15. A Hybrid Path-Oriented Code Assignment CDMA-Based MAC Protocol for Underwater Acoustic Sensor Networks

    Directory of Open Access Journals (Sweden)

    Huifang Chen

    2013-11-01

    Full Text Available Due to the characteristics of underwater acoustic channel, media access control (MAC protocols designed for underwater acoustic sensor networks (UWASNs are quite different from those for terrestrial wireless sensor networks. Moreover, in a sink-oriented network with event information generation in a sensor field and message forwarding to the sink hop-by-hop, the sensors near the sink have to transmit more packets than those far from the sink, and then a funneling effect occurs, which leads to packet congestion, collisions and losses, especially in UWASNs with long propagation delays. An improved CDMA-based MAC protocol, named path-oriented code assignment (POCA CDMA MAC (POCA-CDMA-MAC, is proposed for UWASNs in this paper. In the proposed MAC protocol, both the round-robin method and CDMA technology are adopted to make the sink receive packets from multiple paths simultaneously. Since the number of paths for information gathering is much less than that of nodes, the length of the spreading code used in the POCA-CDMA-MAC protocol is shorter greatly than that used in the CDMA-based protocols with transmitter-oriented code assignment (TOCA or receiver-oriented code assignment (ROCA. Simulation results show that the proposed POCA-CDMA-MAC protocol achieves a higher network throughput and a lower end-to-end delay compared to other CDMA-based MAC protocols.

  16. CA-MAC: A Novel MAC Protocol to Alleviate Congestion in Wireless Sensor Networks

    Directory of Open Access Journals (Sweden)

    WU, J.

    2013-11-01

    Full Text Available Even if the traffic pattern is known and the network topology is simple, a strong congestion can take place in wireless sensor networks (WSNs due to the data gathering effect and the duty-cycle operation. In this paper, we propose a novel medium access control (MAC protocol to alleviate the congestion, which is referred to as the congestion alleviation-MAC (CA-MAC. It adopts an adaptive contention window (ACW, which allows the nodes with more buffered packets to transmit with a higher probability, as well as an intelligent burst packet transmission when the congested nodes seize the channel. Simulations are performed in NS-2, and results show that the proposed CA-MAC protocol achieves a good performance in terms of the packet delivery ratio (PDR, power consumption, throughput, and average latency.

  17. A cooperative MAC protocol with error-aware relay selection for wireless ad hoc networks

    Science.gov (United States)

    Liu, Shanzhi; Liu, Kai; Wang, Rui; Fang, Ruochen; Liu, Feng

    2017-01-01

    To solve performance degradation caused by channel fading, we propose a cooperative MAC protocol with error-aware relay selection for wireless ad hoc networks in this paper. In the protocol, the transmission error of data packet caused by channel fading are considered in order to achieve the best cooperative gain in the poor quality channel. In the relay selection process, potential relay nodes satisfying corresponding requirement can compete to sever as final relay node by means of priority selection and collision resolution process. Finally, simulation results show that the proposed protocol outperforms other protocol in terms of packet error rate and the saturation throughput.

  18. A Mac Protocol Implementation for Wireless Sensor Network

    Directory of Open Access Journals (Sweden)

    Jamila Bhar

    2015-01-01

    Full Text Available IEEE 802.15.4 is an important standard for Low Rate Wireless Personal Area Network (LRWPAN. The IEEE 802.15.4 presents a flexible MAC protocol that provides good efficiency for data transmission by adapting its parameters according to characteristics of different applications. In this research work, some restrictions of this standard are explained and an improvement of traffic efficiency by optimizing MAC layer is proposed. Implementation details for several blocks of communication system are carefully modeled. The protocol implementation is done using VHDL language. The analysis gives a full understanding of the behavior of the MAC protocol with regard to backoff delay, data loss probability, congestion probability, slot effectiveness, and traffic distribution for terminals. Two ideas are proposed and tested to improve efficiency of CSMA/CA mechanism for IEEE 802.15.4 MAC Layer. Primarily, we dynamically adjust the backoff exponent (BE according to queue level of each node. Secondly, we vary the number of consecutive clear channel assessment (CCA for packet transmission. We demonstrate also that slot compensation provided by the enhanced MAC protocol can greatly avoid unused slots. The results show the significant improvements expected by our approach among the IEEE 802.15.4 MAC standards. Synthesis results show also hardware performances of our proposed architecture.

  19. W-MAC: a workload-aware MAC protocol for heterogeneous convergecast in wireless sensor networks.

    Science.gov (United States)

    Xia, Ming; Dong, Yabo; Lu, Dongming

    2011-01-01

    The power consumption and latency of existing MAC protocols for wireless sensor networks (WSNs) are high in heterogeneous convergecast, where each sensor node generates different amounts of data in one convergecast operation. To solve this problem, we present W-MAC, a workload-aware MAC protocol for heterogeneous convergecast in WSNs. A subtree-based iterative cascading scheduling mechanism and a workload-aware time slice allocation mechanism are proposed to minimize the power consumption of nodes, while offering a low data latency. In addition, an efficient schedule adjustment mechanism is provided for adapting to data traffic variation and network topology change. Analytical and simulation results show that the proposed protocol provides a significant energy saving and latency reduction in heterogeneous convergecast, and can effectively support data aggregation to further improve the performance.

  20. Connectivity-Based Reliable Multicast MAC Protocol for IEEE 802.11 Wireless LANs

    Directory of Open Access Journals (Sweden)

    Woo-Yong Choi

    2009-01-01

    Full Text Available We propose the efficient reliable multicast MAC protocol based on the connectivity information among the recipients. Enhancing the BMMM (Batch Mode Multicast MAC protocol, the reliable multicast MAC protocol significantly reduces the RAK (Request for ACK frame transmissions in a reasonable computational time and enhances the MAC performance. By the analytical performance analysis, the throughputs of the BMMM protocol and our proposed MAC protocol are derived. Numerical examples show that our proposed MAC protocol increases the reliable multicast MAC performance for IEEE 802.11 wireless LANs.

  1. APC-MAC/TA: Adaptive Power Controlled MAC Protocol with Traffic Awareness for Wireless Sensor Networks

    Science.gov (United States)

    Woo, Seok; Kim, Kiseon

    In this paper, we propose an adaptive power controlled MAC protocol with a traffic-aware scheme specifically designed to reduce both energy and latency in wireless sensor networks. Typically, existing MAC protocols for sensor networks sacrifice latency performance for node energy efficiency. However, some sensor applications for emergencies require rather fast transmissions of sensed data, where we need to consider both energy and latency together. The proposed MAC protocol includes two novel ideas: one is a transmission power control scheme for improving latency in high traffic loads, and the other is a traffic-aware scheme to save more energy in low traffic loads. The transmission power control scheme increases channel utilization by mitigating interference between nodes, and the traffic-aware scheme allows nodes to sleep to reduce idle energy consumption when there are no traffic loads in a network. Simulation results show that the proposed protocol significantly reduces the latency as well as the energy consumption compared to the S-MAC protocol specifically for a large transmission power of nodes and low network traffic.

  2. Cognitive MAC Protocols for General Primary Network Models

    CERN Document Server

    Mehanna, Omar; Gamal, Hesham El

    2009-01-01

    We consider the design of cognitive Medium Access Control (MAC) protocols enabling a secondary (unlicensed) transmitter-receiver pair to communicate over the idle periods of a set of primary (licensed) channels. More specifically, we propose cognitive MAC protocols optimized for both slotted and un-slotted primary networks. For the slotted structure, the objective is to maximize the secondary throughput while maintaining synchronization between the secondary pair and not causing interference to the primary network. Our investigations differentiate between two sensing scenarios. In the first, the secondary transmitter is capable of sensing all the primary channels, whereas it senses only a subset of the primary channels in the second scenario. In both cases, we propose blind MAC protocols that efficiently learn the statistics of the primary traffic on-line and asymptotically achieve the throughput obtained when prior knowledge of primary traffic statistics is available. For the un-slotted structure, the object...

  3. The Impact of Dynamic RTS Threshold Adjustment for IEEE 802.11 MAC Protocol

    OpenAIRE

    Mostafa Mjidi; Debasish Chakraborty; Naoki Nakamura; Norio Shiratori

    2009-01-01

    In recent years, wireless technologies and application received great attention. The Medium Access Control (MAC) protocol is the main element that determines the efficiency in sharing the limited communication bandwidth of the wireless channel in wireless local area networks (WLANs). IEEE 802.11 introduced the optional RTS/CTS handshaking mechanism to address the hidden terminal problem as well as to reduces the chance of collision in case of higher node density and traffic. RTS Threshold (RT...

  4. An efficient geo-routing aware MAC protocol for underwater acoustic networks

    Directory of Open Access Journals (Sweden)

    Yibo Zhu

    2011-09-01

    Full Text Available In this paper, we propose an efficient geo-routing aware MAC protocol (GOAL for underwater acoustic networks. It smoothly integrates self-adaptation based REQ/REP handshake, geographic cyber carrier sensing, and implicit ACK to perform combined channel reservation and next-hop selection. As a result, it incorporates the advantages of both a geo-routing protocol and a reservation-based medium access control (MAC protocol. Specifically, with its self-adaptation based REQ/REP, nodes can dynamically detect the best next-hop with low route discovery cost. In addition, through geographic cyber carrier sensing, a node can map its neighbors’ time slots for sending/receiving DATA packets to its own time line, which allows the collision among data packets to be greatly reduced. With these features, GOAL outperforms geo-routing protocols coupling with broadcast MAC. Simulation results show that GOAL provides much higher end-to-end reliability with lower energy consumptions than existing Vector-Based Forwarding (VBF routing with use of a broadcast MAC protocol. Moreover, we develop a theoretical model for the probability of a successful handshake, which coincides well with the simulation results.

  5. A Fairness Oriented Neighbor-Channel-Aware MAC Protocol for Airborne Sensor Networks.

    Science.gov (United States)

    Gao, Xiaolin; Yan, Jian; Lu, Jianhua

    2017-05-16

    In airborne sensor networks (ASNs), the media access control (MAC) protocol faces a serious unfairness problem due to the traditional protection mechanism of air-to-air communications among aircraft. Actually, by using the binary exponential back-off algorithm at high traffic loads to minimize collisions among users, the latest successful node can always benefit from this kind of MAC to obtain channel resources. Moreover, when taking the existence of the hidden nodes in ASNs into account, the inaccurate traffic load information will further aggravate the system's unfairness. In this paper, a neighbor-channel-aware (NCA) protocol is proposed to improve the fairness of MAC protocol in ASNs. In the proposal, the NCA frame is firstly added and exchanged between neighbor nodes periodically, which helps to resolve the inaccurate traffic load information, so as to avoid reducing the probability of successful message transmission. Then a traffic-loading based back-off algorithm is involved to make the neighbor nodes cooperatively adjust the inter-frame space (IFS) interval to further reduce the unfairness. The simulation results show that, the proposed MAC protocol can guarantee the satisfied fairness, simultaneously avoiding heavy network overloads to protect key messages' successful transmissions in ASNs.

  6. Cross Layer PHY-MAC Protocol for Wireless Static and Mobile Ad Hoc Networks

    Directory of Open Access Journals (Sweden)

    Chris Blondia

    2008-11-01

    Full Text Available Multihop mobile wireless networks have drawn a lot of attention in recent years thanks to their wide applicability in civil and military environments. Since the existing IEEE 802.11 distributed coordination function (DCF standard does not provide satisfactory access to the wireless medium in multihop mobile networks, we have designed a cross-layer protocol, (CroSs-layer noise aware power driven MAC (SNAPdMac, which consists of two parts. The protocol first concentrates on the flexible adjustment of the upper and lower bounds of the contention window (CW to lower the number of collisions. In addition, it uses a power control scheme, triggered by the medium access control (MAC layer, to limit the waste of energy and also to decrease the number of collisions. Thanks to a noticeable energy conservation and decrease of the number of collisions, it prolongs significantly the lifetime of the network and delays the death of the first node while increasing both the throughput performance and the sending bit rate/throughput fairness among contending flows.

  7. TR-MAC: an energy-efficient MAC protocol exploiting transmitted reference modulation for wireless sensor networks

    NARCIS (Netherlands)

    Morshed, S.; Heijenk, Geert

    2014-01-01

    The medium access control (MAC) protocol determines the energy consumption of a wireless sensor node by specifying the listening, transmitting or sleeping time. Therefore MAC protocols play an important role in minimizing the overall energy consumption in a typical wireless sensor network (WSN).

  8. TR-MAC: an energy-efficient MAC protocol exploiting transmitted reference modulation for wireless sensor networks

    NARCIS (Netherlands)

    Morshed, Sarwar; Heijenk, Geert

    2014-01-01

    The medium access control (MAC) protocol determines the energy consumption of a wireless sensor node by specifying the listening, transmitting or sleeping time. Therefore MAC protocols play an important role in minimizing the overall energy consumption in a typical wireless sensor network (WSN). Usi

  9. Directional Medium Access Control (MAC Protocols in Wireless Ad Hoc and Sensor Networks: A Survey

    Directory of Open Access Journals (Sweden)

    David Tung Chong Wong

    2015-06-01

    Full Text Available This survey paper presents the state-of-the-art directional medium access control (MAC protocols in wireless ad hoc and sensor networks (WAHSNs. The key benefits of directional antennas over omni-directional antennas are longer communication range, less multipath interference, more spatial reuse, more secure communications, higher throughput and reduced latency. However, directional antennas lead to single-/multi-channel directional hidden/exposed terminals, deafness and neighborhood, head-of-line blocking, and MAC-layer capture which need to be overcome. Addressing these problems and benefits for directional antennas to MAC protocols leads to many classes of directional MAC protocols in WAHSNs. These classes of directional MAC protocols presented in this survey paper include single-channel, multi-channel, cooperative and cognitive directional MACs. Single-channel directional MAC protocols can be classified as contention-based or non-contention-based or hybrid-based, while multi-channel directional MAC protocols commonly use a common control channel for control packets/tones and one or more data channels for directional data transmissions. Cooperative directional MAC protocols improve throughput in WAHSNs via directional multi-rate/single-relay/multiple-relay/two frequency channels/polarization, while cognitive directional MAC protocols leverage on conventional directional MAC protocols with new twists to address dynamic spectrum access. All of these directional MAC protocols are the pillars for the design of future directional MAC protocols in WAHSNs.

  10. Spatial Correlation-Based MAC Protocol for Event-Driven Wireless Sensor Networks

    Directory of Open Access Journals (Sweden)

    Guoqiang Zheng

    2011-01-01

    Full Text Available Wireless sensor networks is highly spatial correlated. Recently it has been proposed to select a subset of sensors nodes to transmit their data so as to prevent transmission of redundant data. In this paper, we investigate the ways of selecting sensor nodes and develop a novel spatial correlation-based Medium Access Control (MAC protocol for event-driven wireless sensor networks, referred as SCMAC. Based on a theoretical framework, SCMAC adopts priority node selection algorithm and collision avoidance mechanism so that transmission of redundant data is prevented when contending for the shared channel, while SCMAC prioritizes the transmission of route-thru packets. Simulation results show that our protocol achieves higher performance than CC-MAC in the aspect of energy consumption, transmission latency, packet delivery rate, packet drop rate and reconstruction distortion.

  11. Throughput Analysis of Power Control B-MAC Protocol In WSN

    Directory of Open Access Journals (Sweden)

    Ramchand V

    2012-07-01

    Full Text Available This paper presents a new methodology for energy consumption of nodes and throughput analysis has been performed through simulation for B-MAC protocol in Wireless Sensor Networks. The design includes transmission power control and multi-hop transmission of frames through adjusted transmitted power level. Proposed model reduces collision with contention level notification. The proposed model has been simulated using MATLAB. The simulations reveal better results for throughput of the proposed model as compared to B-MAC protocol. In this model we have included a mechanism for node discovery to find the location of the node before transmission of data to it. This increases the throughput of the network since the position of a dislocated node has been found, that results into successful transmission of frames.However, the energy consumption of a node increases due to energy consumed in node discovery.

  12. An Energy Efficient Analysis of S-MAC And H-MAC Protocols for Wireless Sensor Networks

    Directory of Open Access Journals (Sweden)

    P.T.Kalaivaani

    2013-04-01

    Full Text Available Wireless Sensor Networks (WSNs is an interesting topic to the researchers because of its variousapplications. The applications are health monitoring and environmental monitoring, Industrial ProcessMonitoring, Target detection, Target tracking, Energy Efficiency, Disaster Management and MilitarySecurity Systems. The wireless medium requires highly optimized medium Access Protocols to avoidinterferences. Limited resources have driven the research towards energy consumption of MACfunctionalities. Two Medium Access Control (MAC protocol performances are analyzed by using the MAClayer frame work for wireless sensor networks. In this paper an energy efficient analysis of S-MAC and HMACprotocols for wireless sensor networks is proposed with spatial correlation concept. Two MACprotocols such as Sensor MAC (S-MAC and Hybrid MAC (H-MAC protocols are proposed to analyze theperformance of Wireless Sensor Network using four different Parameters such as End to End delay, PacketDelivery Ratio, Packet Drop Rate and Energy Consumption. Performance analysis is carried out by usingthe simulation tool NS2.

  13. Cognitive Radio MAC Protocol for WLAN

    DEFF Research Database (Denmark)

    Zhang, Qi; Fitzek, Frank H.P.; Iversen, Villy Bæk

    2008-01-01

    To solve the performance degradation issue in current WLAN caused by the crowded unlicensed spectrum, we propose a cognitive radio (CR) media access protocol, C-CSMA/CA. The basic idea is that with cognitive radio techniques the WLAN devices can not only access the legacy WLAN unlicensed spectrum...... hole; moreover, it designs dual inband sensing scheme to detect primary user appearance. Additionally, C-CSMA/CA has the advantage to effectively solve the cognitive radio self-coexistence issues in the overlapping CR BSSs scenario. It also realizes station-based dynamic resource selection...... and utilization. It is compatible with any legacy WLAN (BSS) system. We develop and implement the simulation of C-CSMA/CA by OPNET. The simulation results show that C-CSMA/CA highly enhances throughput and reduces the queuing delay and media access delay....

  14. TreeMAC: Localized TDMA MAC protocol for real-time high-data-rate sensor networks

    Science.gov (United States)

    Song, W.-Z.; Huang, R.; Shirazi, B.; LaHusen, R.

    2009-01-01

    Earlier sensor network MAC protocols focus on energy conservation in low-duty cycle applications, while some recent applications involve real-time high-data-rate signals. This motivates us to design an innovative localized TDMA MAC protocol to achieve high throughput and low congestion in data collection sensor networks, besides energy conservation. TreeMAC divides a time cycle into frames and each frame into slots. A parent node determines the children's frame assignment based on their relative bandwidth demand, and each node calculates its own slot assignment based on its hop-count to the sink. This innovative 2-dimensional frame-slot assignment algorithm has the following nice theory properties. First, given any node, at any time slot, there is at most one active sender in its neighborhood (including itself). Second, the packet scheduling with TreeMAC is bufferless, which therefore minimizes the probability of network congestion. Third, the data throughput to the gateway is at least 1/3 of the optimum assuming reliable links. Our experiments on a 24-node testbed show that TreeMAC protocol significantly improves network throughput, fairness, and energy efficiency compared to TinyOS's default CSMA MAC protocol and a recent TDMA MAC protocol Funneling-MAC. Partial results of this paper were published in Song, Huang, Shirazi and Lahusen [W.-Z. Song, R. Huang, B. Shirazi, and R. Lahusen, TreeMAC: Localized TDMA MAC protocol for high-throughput and fairness in sensor networks, in: The 7th Annual IEEE International Conference on Pervasive Computing and Communications, PerCom, March 2009]. Our new contributions include analyses of the performance of TreeMAC from various aspects. We also present more implementation detail and evaluate TreeMAC from other aspects. ?? 2009 Elsevier B.V.

  15. A slotted floor acquisition multiple access based MAC protocol for underwater acoustic networks with RTS competition

    Institute of Scientific and Technical Information of China (English)

    Liang-fang QIAN; Sen-lin ZHANG; Mei-qin LIU

    2015-01-01

    Long propagation delay, limited bandwidth, and high bit error rate pose great challenges in media access control (MAC) protocol design for underwater acoustic networks. A MAC protocol called slotted fl oor acquisition multiple access (slotted-FAMA) suitable for underwater acoustic networks is proposed and analyzed. This FAMA based protocol adds a time slot mechanism to avoid DATA packet collisions. However, slotted-FAMA is not suitable for dense networks since the multiple request-to-send (RTS) attempts problem in dense networks is serious and greatly limits the network throughput. To overcome this drawback, this paper proposes a slotted-FAMA based MAC protocol for underwater acoustic networks, called RC-SFAMA. RC-SFAMA introduces an RTS competition mechanism to keep the network from high frequency of backoff caused by the multiple RTS attempts problem. Via the RTS competition mechanism, useful data transmission can be completed successfully when the situation of multiple RTS attempts occurs. Simulation results show that RC-SFAMA increases the network throughput efficiency as compared with slotted-FAMA, and minimizes the energy consumption.

  16. On the Development of Low Power MAC Protocol for WBANs

    CERN Document Server

    Ullah, Sana; Kwak, Kyung Sup

    2009-01-01

    Current advances in wireless communication, microelectronics, semiconductor technologies, and intelligent sensors have contributed to the development of unobtrusive WBANs. These networks provide long term health monitoring of patients without any constraint in their normal activities. Traditional MAC protocols do not accommodate the assorted WBAN traffic requirements in a power efficient manner. In this paper, we present a brief discussion on the development process of a low power MAC protocol for WBANs. We observe the behavior of a beacon-enabled IEEE 802.15.4 for on-body sensor networks. We further propose a low power technique called traffic based wakeup mechanism for a WBAN that exploits the traffic patterns of the BAN Nodes to ensure power efficient and reliable communication.

  17. History-based MAC Protocol for Low Duty-Cycle Wireless Sensor Networks: the SLACK-MAC Protocol

    Directory of Open Access Journals (Sweden)

    Affoua Thérèse Aby

    2016-06-01

    Full Text Available Wireless sensor networks (WSNs are increasingly used in environmental monitoring applications. They are designed to operate for several months by featuring low activity cycles in order to save energy. In this paper, we propose a Medium Access Control (MAC protocol for suchWSNs with very low duty-cycles of 1% and less. Nodes are activated randomly and use a history of previous successful frame exchanges to decide their next activation time. We study the choice of the history size, and we compare the performance of our protocol with other protocols from the literature. We show by simulations and real experiments that with a limited history size of only six entries, our protocol achieves better performance than other protocols from the literature, while keeping the advantages of fully asynchronous protocols.

  18. RLT Code Based Handshake-Free Reliable MAC Protocol for Underwater Sensor Networks

    Directory of Open Access Journals (Sweden)

    Xiujuan Du

    2016-01-01

    Full Text Available The characteristics of underwater acoustic channels such as long propagation delay and low bit rate cause the medium access control (MAC protocols designed for radio channels to either be inapplicable or have low efficiency for underwater sensor networks (UWSNs. Meanwhile, due to high bit error, conventional end-to-end reliable transfer solutions bring about too many retransmissions and are inefficient in UWSN. In this paper, we present a recursive LT (RLT code. With small degree distribution and recursive encoding, RLT achieves reliable transmission hop-by-hop while reducing the complexity of encoding and decoding in UWSN. We further propose an RLT code based handshake-free (RCHF reliable MAC protocol. In RCHF protocol, each node maintains a neighbor table including the field of state, and packages are forwarded according to the state of a receiver, which can avoid collisions of sending-receiving and overhearing. The transmission-avoidance time in RCHF decreases data-ACK collision dramatically. Without RTS/CTS handshaking, the RCHF protocol improves channel utilization while achieving reliable transmission. Simulation results show that, compared with the existing reliable data transport approaches for underwater networks, RCHF can improve network throughput while decreasing end-to-end overhead.

  19. TreeMAC: Localized TDMA MAC protocol for real-time high-data-rate sensor networks

    Science.gov (United States)

    Song, W.-Z.; Huang, R.; Shirazi, B.; Husent, R.L.

    2009-01-01

    Earlier sensor network MAC protocols focus on energy conservation in low-duty cycle applications, while some recent applications involve real-time high-data-rate signals. This motivates us to design an innovative localized TDMA MAC protocol to achieve high throughput and low congestion in data collection sensor networks, besides energy conservation. TreeMAC divides a time cycle into frames and frame into slots. Parent determines children's frame assigmnent based on their relative bandwidth demand, and each node calculates its own slot assignment based on its hop-count to the sink. This innovative 2-dimensional frame-slot assignment algorithm has the following nice theory properties. Firstly, given any node, at any time slot, there is at most one active sender in its neighborhood (includ ing itself). Secondly, the packet scheduling with TreelMAC is bufferless, which therefore minimizes the probability of network congestion. Thirdly, the data throughput to gateway is at least 1/3 of the optimum assuming reliable links. Our experiments on a 24 node test bed demonstrate that TreeMAC protocol significantly improves network throughput and energy efficiency, by comparing to the TinyOS's default CSMA MAC protocol and a recent TDMA MAC protocol Funneling-MAC[8]. ?? 2009 IEEE.

  20. Intelligent Cooperative MAC Protocol for Balancing Energy Consumption

    Science.gov (United States)

    Wu, S.; Liu, K.; Huang, B.; Liu, F.

    To extend the lifetime of wireless sensor networks, we proposed an intelligent balanced energy consumption cooperative MAC protocol (IBEC-CMAC) based on the multi-node cooperative transmission model. The protocol has priority to access high-quality channels for reducing energy consumption of each transmission. It can also balance the energy consumption among cooperative nodes by using high residual energy nodes instead of excessively consuming some node's energy. Simulation results show that IBEC-CMAC can obtain longer network lifetime and higher energy utilization than direct transmission.

  1. Multi-Hop-Enabled Energy-Efficient MAC Protocol for Underwater Acoustic Sensor Networks

    Directory of Open Access Journals (Sweden)

    Khaja Shazzad

    2015-09-01

    Full Text Available In multi-hop underwater acoustic sensor networks (UWASNs, packet collisions due to hidden and local nodes adversely affect throughput, energy efficiency and end-to-end delay. Existing medium access control (MAC protocols try to solve the problem by utilizing a single-phase contention resolution mechanism, which causes a large number of control packet exchanges and energy overhead. In this paper, we introduce a MAC protocol that splits this single-phase contention resolution mechanism into two phases to provide efficient multi-hop networking. In the first phase, local nodes are eliminated from the contention, and in the later phase, the adverse effects of hidden nodes are mitigated. This two-phased contention resolution provides higher energy efficiency, better throughput and shorter end-to-end delay, and it also enables adaptability for different network architectures. A probabilistic model of the proposed protocol is also developed to analyse the performance. The proposed protocol has been evaluated through quantitative analysis and simulation. Results obtained through quantitative analysis and simulation reveal that the proposed protocol achieves significantly better energy efficiency, higher and more stable throughput and lower end-to-end delay compared to existing protocols, namely T-Lohi and slotted floor acquisition multiple access (S-FAMA.

  2. MAC Protocols for GSP in Wireless Sensor Networks

    Directory of Open Access Journals (Sweden)

    Maria Calle

    2008-06-01

    Full Text Available The Gossip-based Sleep Protocol (GSP is a routing protocol designed to save energy in Wireless Sensor Networks. This work presents two MAC protocols designed to complement the characteristics of GSP: MACGSP1 and MACGSP2 were evaluated in combination with GSP on square grids of 100, 400 and 900 simulated nodes. Both protocols show increased energy savings compared to GSP by itself. MACGSP1 provided the greatest energy savings, however MACGSP2 exhibited the best trade off between overhead, delay and packet reception probability. MACGSP2 reduces the duplicate packets generated by GSP, with no significant difference in end-to end delay and a reduced GSP packet reception probability of 10%.

  3. Design of an Efficient MAC Protocol for Opportunistic Cognitive Radio Networks

    Directory of Open Access Journals (Sweden)

    Mahfuzulhoq Chowdhury

    2012-11-01

    Full Text Available Cognitive radio technology has been developed in recent years to make efficient use of the wirelessspectrum especially for opportunistic spectrum access. Cognitive radio technology enables the secondary(cognitive users to use the unused licensed spectrum of the primary users. Medium Access Control (MACprotocol plays a vital role in spectrum utilization, primary user’s (PU interference management andsecondary user’s coordination in cognitive radio (CR networks. Here, we propose a new MAC protocolwhere control transceiver attached with sensor improves the accuracy of spectrum sensing result as well asprotects the primary user from interference. In our proposed MAC protocol, each secondary user (SU isequipped with two radios, solves the multichannel hidden terminal problem (MHTP. Our proposed MACprotocol considers collision avoidance among SU’s and between SU’s and PU’s. We develop an analyticalmodel validated by simulation. Our scheme improves the network throughput in presence of sensing error.

  4. Autonomous Power Control MAC Protocol for Mobile Ad Hoc Networks

    Directory of Open Access Journals (Sweden)

    2006-01-01

    Full Text Available Battery energy limitation has become a performance bottleneck for mobile ad hoc networks. IEEE 802.11 has been adopted as the current standard MAC protocol for ad hoc networks. However, it was developed without considering energy efficiency. To solve this problem, many modifications on IEEE 802.11 to incorporate power control have been proposed in the literature. The main idea of these power control schemes is to use a maximum possible power level for transmitting RTS/CTS and the lowest acceptable power for sending DATA/ACK. However, these schemes may degrade network throughput and reduce the overall energy efficiency of the network. This paper proposes autonomous power control MAC protocol (APCMP, which allows mobile nodes dynamically adjusting power level for transmitting DATA/ACK according to the distances between the transmitter and its neighbors. In addition, the power level for transmitting RTS/CTS is also adjustable according to the power level for DATA/ACK packets. In this paper, the performance of APCMP protocol is evaluated by simulation and is compared with that of other protocols.

  5. A new multi-channel MAC protocol based on CDMA for ad hoc networks%一种基于CDMA的多信道自组网MAC协议

    Institute of Scientific and Technical Information of China (English)

    贾旻; 陈惠民; 袁玉华

    2007-01-01

    This paper proposes a novel multichannel medium access control (MAC) protocol based on CDMA that improves network performance and reduces collision probability in wireless ad hoc networks. In the scheme, the code channel is divided into common channel, broadcast channel and several data channels. Simulation results show that the proposed protocol can achieve significantly better performance than the IEEE 802.11 standard.

  6. TMAC: Timestamp-Ordered MAC Protocol for Wireless Mesh Networks

    KAUST Repository

    Nawab, Faisal

    2011-05-01

    Wireless Mesh Networks (WMNs) have emerged to meet a need for a self-organized and self-configured multi-hop wireless network infrastructure. Low cost infrastructure and ease of deployment have made WMNs an attractive technology for last mile access. However, 802.11 based WMNs are subject to serious fairness issues. With backlogged TCP traffic, nodes which are two or more hops away from the gateway are subject to starvation, while the one-hop away node saturates the channel with its own local traffic. We study the interactions of TCP and IEEE 802.11 MAC in WMNs to aid us in understanding and overcoming the unfairness problem. We propose a Markov chain to capture the behavior of TCP sessions, particularly the impact on network throughput performance due to the effect of queue utilization and packet relaying. A closed form solution is derived to numerically derive the throughput. Based on the developed model, we propose a distributed MAC protocol called Timestamp-ordered MAC (TMAC), aiming to alleviate the unfairness problem in WMNs via a manipulative per-node scheduling mechanism which takes advantage of the age of each packet as a priority metric. Simulation is conducted to validate our model and to illustrate the fairness characteristics of TMAC. Our results show that TMAC achieves excellent resource allocation fairness while maintaining above 90% of maximum link capacity in parking lot and large grid topologies. Our work illuminates the factors affecting TCP fairness in WMNs. Our theoretical and empirical findings can be used in future research to develop more fairness-aware protocols for WMNs.

  7. Traffic-adaptive duty cycle adaptation in TR-MAC protocol for wireless sensor networks

    NARCIS (Netherlands)

    Morshed, Sarwar; Baratchi, Mitra; Heijenk, Geert

    2016-01-01

    The Medium Access Control (MAC) layer can influence the energy consumption of a wireless sensor network (WSN) to a significant level. TR-MAC is an energy-efficient preamble sampling based MAC protocol for low power WSNs suitable for low data rate and low duty cycle scenario. However, low data rate i

  8. A Distributed MAC Protocol for Cooperation in Random Access Networks

    CERN Document Server

    Böcherer, Georg

    2008-01-01

    WLAN is one of the most successful applications of wireless communications in daily life because of low cost and ease of deployment. The enabling technique for this success is the use of random access schemes for the wireless channel. Random access requires minimal coordination between the nodes, which considerably reduces the cost of the infrastructure. Recently, cooperative communication in wireless networks has been of increasing interest because it promises higher rates and reliability. An additional MAC overhead is necessary to coordinate the nodes to allow cooperation and this overhead can possibly cancel out the cooperative benefits. In this work, a completely distributed protocol is proposed that allows nodes in the network to cooperate via Two-Hop and Decode-and-Forward for transmitting their data to a common gateway node. It is shown that high throughput gains are obtained in terms of the individual throughput that can be guaranteed to any node in the network. These results are validated by Monte Ca...

  9. An Empirical Study and some Improvements of the MiniMac Protocol for Secure Computation

    DEFF Research Database (Denmark)

    Damgård, Ivan Bjerre; Lauritsen, Rasmus; Toft, Tomas

    2014-01-01

    (nicknamed MiniMac). While TinyOT has already been implemented, we present in this paper the first implementation of MiniMac, using the same platform as the existing TinyOT implementation. We also suggest several improvements of MiniMac, both on the protocol design and implementation level. In particular, we...... suggest a modification of MiniMac that achieves increased parallelism at no extra communication cost. This gives an asymptotic improvement of the original protocol as well as an 8-fold speed-up of our implementation. We compare the resulting protocol to TinyOT for the case of secure computation in parallel...

  10. MAC Protocol for Ad Hoc Networks Using a Genetic Algorithm

    Directory of Open Access Journals (Sweden)

    Omar Elizarraras

    2014-01-01

    Full Text Available The problem of obtaining the transmission rate in an ad hoc network consists in adjusting the power of each node to ensure the signal to interference ratio (SIR and the energy required to transmit from one node to another is obtained at the same time. Therefore, an optimal transmission rate for each node in a medium access control (MAC protocol based on CSMA-CDMA (carrier sense multiple access-code division multiple access for ad hoc networks can be obtained using evolutionary optimization. This work proposes a genetic algorithm for the transmission rate election considering a perfect power control, and our proposition achieves improvement of 10% compared with the scheme that handles the handshaking phase to adjust the transmission rate. Furthermore, this paper proposes a genetic algorithm that solves the problem of power combining, interference, data rate, and energy ensuring the signal to interference ratio in an ad hoc network. The result of the proposed genetic algorithm has a better performance (15% compared to the CSMA-CDMA protocol without optimizing. Therefore, we show by simulation the effectiveness of the proposed protocol in terms of the throughput.

  11. Optimization and verification of the TR-MAC protocol for wireless sensor networks

    NARCIS (Netherlands)

    Morshed, Sarwar; Heijenk, Geert

    2015-01-01

    Energy-efficiency is an important requirement in the design of communication protocols for wireless sensor networks (WSN). TR-MAC is an energy-efficient medium access control (MAC) layer protocol for low power WSN that exploits transmitted-reference (TR) modulation in the physical layer. The underly

  12. Power-Controlled MAC Protocols with Dynamic Neighbor Prediction for Ad hoc Networks

    Institute of Scientific and Technical Information of China (English)

    LI Meng; ZHANG Lin; XIAO Yong-kang; SHAN Xiu-ming

    2004-01-01

    Energy and bandwidth are the scarce resources in ad hoc networks because most of the mobile nodes are battery-supplied and share the exclusive wireless medium. Integrating the power control into MAC protocol is a promising technique to fully exploit these precious resources of ad hoc wireless networks. In this paper, a new intelligent power-controlled Medium Access Control (MAC) (iMAC) protocol with dynamic neighbor prediction is proposed. Through the elaborate design of the distributed transmit-receive strategy of mobile nodes, iMAC greatly outperforms the prevailing IEEE 802.11 MAC protocols in not only energy conservation but also network throughput. Using the Dynamic Neighbor Prediction (DNP), iMAC performs well in mobile scenes. To the best of our knowledge, iMAC is the first protocol that considers the performance deterioration of power-controlled MAC protocols in mobile scenes and then proposes a solution. Simulation results indicate that DNP is important and necessary for power-controlled MAC protocols in mobile ad hoc networks.

  13. Potential of Wake-Up Radio-Based MAC Protocols for Implantable Body Sensor Networks (IBSN—A Survey

    Directory of Open Access Journals (Sweden)

    Vignesh Raja Karuppiah Ramachandran

    2016-11-01

    Full Text Available With the advent of nano-technology, medical sensors and devices are becoming highly miniaturized. Consequently, the number of sensors and medical devices being implanted to accurately monitor and diagnose a disease is increasing. By measuring the symptoms and controlling a medical device as close as possible to the source, these implantable devices are able to save lives. A wireless link between medical sensors and implantable medical devices is essential in the case of closed-loop medical devices, in which symptoms of the diseases are monitored by sensors that are not placed in close proximity of the therapeutic device. Medium Access Control (MAC is crucial to make it possible for several medical devices to communicate using a shared wireless medium in such a way that minimum delay, maximum throughput, and increased network life-time are guaranteed. To guarantee this Quality of Service (QoS, the MAC protocols control the main sources of limited resource wastage, namely the idle-listening, packet collisions, over-hearing, and packet loss. Traditional MAC protocols designed for body sensor networks are not directly applicable to Implantable Body Sensor Networks (IBSN because of the dynamic nature of the radio channel within the human body and the strict QoS requirements of IBSN applications. Although numerous MAC protocols are available in the literature, the majority of them are designed for Body Sensor Network (BSN and Wireless Sensor Network (WSN. To the best of our knowledge, there is so far no research paper that explores the impact of these MAC protocols specifically for IBSN. MAC protocols designed for implantable devices are still in their infancy and one of their most challenging objectives is to be ultra-low-power. One of the technological solutions to achieve this objective so is to integrate the concept of Wake-up radio (WuR into the MAC design. In this survey, we present a taxonomy of MAC protocols based on their use of Wu

  14. Potential of Wake-Up Radio-Based MAC Protocols for Implantable Body Sensor Networks (IBSN)-A Survey.

    Science.gov (United States)

    Karuppiah Ramachandran, Vignesh Raja; Ayele, Eyuel D; Meratnia, Nirvana; Havinga, Paul J M

    2016-11-29

    With the advent of nano-technology, medical sensors and devices are becoming highly miniaturized. Consequently, the number of sensors and medical devices being implanted to accurately monitor and diagnose a disease is increasing. By measuring the symptoms and controlling a medical device as close as possible to the source, these implantable devices are able to save lives. A wireless link between medical sensors and implantable medical devices is essential in the case of closed-loop medical devices, in which symptoms of the diseases are monitored by sensors that are not placed in close proximity of the therapeutic device. Medium Access Control (MAC) is crucial to make it possible for several medical devices to communicate using a shared wireless medium in such a way that minimum delay, maximum throughput, and increased network life-time are guaranteed. To guarantee this Quality of Service (QoS), the MAC protocols control the main sources of limited resource wastage, namely the idle-listening, packet collisions, over-hearing, and packet loss. Traditional MAC protocols designed for body sensor networks are not directly applicable to Implantable Body Sensor Networks (IBSN) because of the dynamic nature of the radio channel within the human body and the strict QoS requirements of IBSN applications. Although numerous MAC protocols are available in the literature, the majority of them are designed for Body Sensor Network (BSN) and Wireless Sensor Network (WSN). To the best of our knowledge, there is so far no research paper that explores the impact of these MAC protocols specifically for IBSN. MAC protocols designed for implantable devices are still in their infancy and one of their most challenging objectives is to be ultra-low-power. One of the technological solutions to achieve this objective so is to integrate the concept of Wake-up radio (WuR) into the MAC design. In this survey, we present a taxonomy of MAC protocols based on their use of WuR technology and identify

  15. Self-Adaptive and Energy-Efficient MAC Protocol Based on Event-Driven

    Directory of Open Access Journals (Sweden)

    Xin Hou

    2013-01-01

    Full Text Available Combined with WSN MAC layer protocol characteristics and design requirements, according to the characteristic of WSN monitoring application requirements, this paper puts forward a method based on event driven MAC protocol. The agreement algorithm is to solve the problem of network congestion and node energy unnecessary consumption cause by a large number of redundant monitoring data transceiver. It is a kind of adaptive low power consumption of the MAC layer protocol, which is pointed out based on theoretical foundation of S_MAC protocol, made use of the event driven mechanism system theory, combined with event driven mechanism and the characteristics of the WSN. It has the periodic dormancy mechanism of S_MAC protocol, in the premise of the reliability data, to reduce data redundancy and communication delay time, improve the overall network throughput, to ensure the safety and reliability of the network, which can greatly extends  the node of working time.

  16. Energy efficient TDMA-based MAC protocol associated with GAF for wireless sensor networks

    Institute of Scientific and Technical Information of China (English)

    XIAO Xiao; ZHENG Bao-yu; YAN Zhen-ya; CHEN Chao

    2007-01-01

    The design of media access control (MAC) protocol for wireless sensor networks (WSNs) with the idea of cross layer attracts more and more attention. People can improve the MAC protocol by obtaining certain information regarding the network layer and physical layer. This article synthesizes and optimizes certain cross-layer protocols which have existed. On the basis of the routing, topology information in the network layer, and transmission power information in the physical layer, the time slot assignment algorithm has been improved in the MAC layer.By using geographical adaptive fidelity algorithm (GAF) to divide the grids, controlling of transmission power and scheduling the work/sleep duty cycle for sensor nodes, a new MAC protocol has been proposed to decrease energy consumption and enlarge the lifetime of WSNs. Simulation results show that the MAC protocol functions well.

  17. Emergency Handling for MAC Protocol in Human Body Communication

    Directory of Open Access Journals (Sweden)

    Kwon Youngmi

    2011-01-01

    Full Text Available The human body communication (HBC is a technology that enables short range data communication using the human body as a medium, like an electrical wire. Thus it removes the need for a traditional antenna. HBC may be used as a type of data communication in body area network (BAN, while the devices are being in contact with body. One of important issues in BAN is an emergency alarm because it may be closely related to human life. For emergency data communication, the most critical factor is the time constraint. IEEE 802.15.6 specifies that the emergency alarm for the BAN must be notified in less than 1 sec and must provide prioritization mechanisms for emergency traffic and notification. As one type of BAN, the HBC must follow this recommendation, too. Existing emergency handling methods in BAN are based on the carrier sensing capability on radio frequencies to detect the status of channels. However, PHY protocol in HBC does not provide the carrier sensing. So the previous methods are not well suitable for HBC directly. Additionally, in the environment that the emergency rate is very low, the allocation of dedicated slot(s for emergency in each superframe is very wasteful. In this work, we proposed specific emergency handling operation for human body communication's medium access control (HBC-MAC protocol to meet the emergency requirements for BAN. We also showed the optimal number of emergency slots for the various combinations of beacon intervals and emergency rates.

  18. A New MAC Protocol with Pseudo-TDMA Behavior for Supporting Quality of Service in 802.11 Wireless LANs

    Directory of Open Access Journals (Sweden)

    2006-01-01

    Full Text Available A new medium access control (MAC protocol is proposed for quality-of-service (QoS support in wireless local area networks (WLAN. The protocol is an alternative to the recent enhancement 802.11e. A new priority policy provides the system with better performance by simulating time division multiple access (TDMA functionality. Collisions are reduced and starvation of low-priority classes is prevented by a distributed admission control algorithm. The model performance is found analytically extending previous work on this matter. The results show that a better organization of resources is achieved through this scheme. Throughput analysis is verified with OPNET simulations.

  19. A Study on the Distributed Antenna Based Heterogeneous Cognitive Wireless Network Synchronous MAC Protocol

    Directory of Open Access Journals (Sweden)

    Lian-Fen Huang

    2015-01-01

    Full Text Available This paper introduces distributed antennas into a cognitive radio network and presents a heterogeneous network. The best contribution of this paper is that it designs a synchronous cognitive MAC protocol (DAHCWNS-MAC protocol: distributed antenna based heterogeneous cognitive wireless network synchronous MAC protocol. The novel protocol aims at combining the advantages of cognitive radio and distributed antennas to fully utilize the licensed spectrum, broaden the communication range, and improve throughput. This paper carries out the mathematical modeling and performance simulation to demonstrate its superiority in improving the network throughput at the cost of increasing antenna hardware costs.

  20. Reliable Multicast MAC Protocol for IEEE 802.11 Wireless LANs with Extended Service Range

    Science.gov (United States)

    Choi, Woo-Yong

    2011-11-01

    In this paper, we propose the efficient reliable multicast MAC protocol by which the AP (Access Point) can transmit reliably its multicast data frames to the recipients in the AP's one-hop or two-hop transmission range. The AP uses the STAs (Stations) that are directly associated with itself as the relays for the data delivery to the remote recipients that cannot be reached directly from itself. Based on the connectivity information among the recipients, the reliable multicast MAC protocol optimizes the number of the RAK (Request for ACK) frame transmissions in a reasonable computational time. Numerical examples show that our proposed MAC protocol significantly enhances the MAC performance compared with the BMMM (Batch Mode Multicast MAC) protocol that is extended to support the recipients that are in the AP's one-hop or two-hop transmission range in IEEE 802.11 wireless LANs.

  1. Research on low-latency MAC protocols for wireless sensor networks

    Science.gov (United States)

    He, Chenguang; Sha, Xuejun; Lee, Chankil

    2007-11-01

    Energy-efficient should not be the only design goal in MAC protocols for wireless sensor networks, which involve the use of battery-operated computing and sensing devices. Low-latency operation becomes the same important as energy-efficient in the case that the traffic load is very heavy or the real-time constrain is used in applications like tracking or locating. This paper introduces some causes of traditional time delays which are inherent in a multi-hops network using existing WSN MAC protocols, illuminates the importance of low-latency MAC design for wireless sensor networks, and presents three MACs as examples of low-latency protocols designed specially for sleep delay, wait delay and wakeup delay in wireless sensor networks, respectively. The paper also discusses design trade-offs with emphasis on low-latency and points out their advantages and disadvantages, together with some design considerations and suggestions for MAC protocols for future applications and researches.

  2. TR-MAC: an energy-efficient MAC protocol for wireless sensor networks exploiting noise-based transmitted reference modulation

    NARCIS (Netherlands)

    Morshed, S.; Dimitrova, D.C.; Brogle, M.; Braun, T.; Heijenk, Gerhard J.

    Energy-constrained behavior of sensor nodes is one of the most important criteria for successful deployment of wireless sensor net- works. The medium access control (MAC) protocol determines the time a sensor node transceiver spends listening or transmitting, and hence the energy consumption of the

  3. Optimizing the MAC Protocol in Localization Systems Based on IEEE 802.15.4 Networks

    Directory of Open Access Journals (Sweden)

    Juan J. Pérez-Solano

    2017-07-01

    Full Text Available Radio frequency signals are commonly used in the development of indoor localization systems. The infrastructure of these systems includes some beacons placed at known positions that exchange radio packets with users to be located. When the system is implemented using wireless sensor networks, the wireless transceivers integrated in the network motes are usually based on the IEEE 802.15.4 standard. But, the CSMA-CA, which is the basis for the medium access protocols in this category of communication systems, is not suitable when several users want to exchange bursts of radio packets with the same beacon to acquire the radio signal strength indicator (RSSI values needed in the location process. Therefore, new protocols are necessary to avoid the packet collisions that appear when multiple users try to communicate with the same beacons. On the other hand, the RSSI sampling process should be carried out very quickly because some systems cannot tolerate a large delay in the location process. This is even more important when the RSSI sampling process includes measures with different signal power levels or frequency channels. The principal objective of this work is to speed up the RSSI sampling process in indoor localization systems. To achieve this objective, the main contribution is the proposal of a new MAC protocol that eliminates the medium access contention periods and decreases the number of packet collisions to accelerate the RSSI collection process. Moreover, the protocol increases the overall network throughput taking advantage of the frequency channel diversity. The presented results show the suitability of this protocol for reducing the RSSI gathering delay and increasing the network throughput in simulated and real environments.

  4. Optimizing the MAC Protocol in Localization Systems Based on IEEE 802.15.4 Networks.

    Science.gov (United States)

    Pérez-Solano, Juan J; Claver, Jose M; Ezpeleta, Santiago

    2017-07-06

    Radio frequency signals are commonly used in the development of indoor localization systems. The infrastructure of these systems includes some beacons placed at known positions that exchange radio packets with users to be located. When the system is implemented using wireless sensor networks, the wireless transceivers integrated in the network motes are usually based on the IEEE 802.15.4 standard. But, the CSMA-CA, which is the basis for the medium access protocols in this category of communication systems, is not suitable when several users want to exchange bursts of radio packets with the same beacon to acquire the radio signal strength indicator (RSSI) values needed in the location process. Therefore, new protocols are necessary to avoid the packet collisions that appear when multiple users try to communicate with the same beacons. On the other hand, the RSSI sampling process should be carried out very quickly because some systems cannot tolerate a large delay in the location process. This is even more important when the RSSI sampling process includes measures with different signal power levels or frequency channels. The principal objective of this work is to speed up the RSSI sampling process in indoor localization systems. To achieve this objective, the main contribution is the proposal of a new MAC protocol that eliminates the medium access contention periods and decreases the number of packet collisions to accelerate the RSSI collection process. Moreover, the protocol increases the overall network throughput taking advantage of the frequency channel diversity. The presented results show the suitability of this protocol for reducing the RSSI gathering delay and increasing the network throughput in simulated and real environments.

  5. A MAC Protocol to Support Monitoring of Underwater Spaces †

    Science.gov (United States)

    Santos, Rodrigo; Orozco, Javier; Ochoa, Sergio F.; Meseguer, Roc; Eggly, Gabriel; Pistonesi, Marcelo F.

    2016-01-01

    Underwater sensor networks are becoming an important field of research, because of their everyday increasing application scope. Examples of their application areas are environmental and pollution monitoring (mainly oil spills), oceanographic data collection, support for submarine geolocalization, ocean sampling and early tsunamis alert. The challenge of performing underwater communications is well known, provided that radio signals are useless in this medium, and a wired solution is too expensive. Therefore, the sensors in these networks transmit their information using acoustic signals that propagate well under water. This data transmission type not only brings an opportunity, but also several challenges to the implementation of these networks, e.g., in terms of energy consumption, data transmission and signal interference. In order to help advance the knowledge in the design and implementation of these networks for monitoring underwater spaces, this paper proposes a MAC protocol for acoustic communications between the nodes, based on a self-organized time division multiple access mechanism. The proposal was evaluated using simulations of a real monitoring scenario, and the obtained results are highly encouraging. PMID:27355950

  6. A MAC Protocol to Support Monitoring of Underwater Spaces

    Directory of Open Access Journals (Sweden)

    Rodrigo Santos

    2016-06-01

    Full Text Available Underwater sensor networks are becoming an important field of research, because of their everyday increasing application scope. Examples of their application areas are environmental and pollution monitoring (mainly oil spills, oceanographic data collection, support for submarine geolocalization, ocean sampling and early tsunamis alert. The challenge of performing underwater communications is well known, provided that radio signals are useless in this medium, and a wired solution is too expensive. Therefore, the sensors in these networks transmit their information using acoustic signals that propagate well under water. This data transmission type not only brings an opportunity, but also several challenges to the implementation of these networks, e.g., in terms of energy consumption, data transmission and signal interference. In order to help advance the knowledge in the design and implementation of these networks for monitoring underwater spaces, this paper proposes a MAC protocol for acoustic communications between the nodes, based on a self-organized time division multiple access mechanism. The proposal was evaluated using simulations of a real monitoring scenario, and the obtained results are highly encouraging.

  7. A MAC Protocol to Support Monitoring of Underwater Spaces.

    Science.gov (United States)

    Santos, Rodrigo; Orozco, Javier; Ochoa, Sergio F; Meseguer, Roc; Eggly, Gabriel; Pistonesi, Marcelo F

    2016-01-01

    Underwater sensor networks are becoming an important field of research, because of their everyday increasing application scope. Examples of their application areas are environmental and pollution monitoring (mainly oil spills), oceanographic data collection, support for submarine geolocalization, ocean sampling and early tsunamis alert. The challenge of performing underwater communications is well known, provided that radio signals are useless in this medium, and a wired solution is too expensive. Therefore, the sensors in these networks transmit their information using acoustic signals that propagate well under water. This data transmission type not only brings an opportunity, but also several challenges to the implementation of these networks, e.g., in terms of energy consumption, data transmission and signal interference. In order to help advance the knowledge in the design and implementation of these networks for monitoring underwater spaces, this paper proposes a MAC protocol for acoustic communications between the nodes, based on a self-organized time division multiple access mechanism. The proposal was evaluated using simulations of a real monitoring scenario, and the obtained results are highly encouraging.

  8. GSR-TDMA: A Geometric Spatial Reuse-Time Division Multiple Access MAC Protocol for Multihop Underwater Acoustic Sensor Networks

    Directory of Open Access Journals (Sweden)

    Changho Yun

    2016-01-01

    Full Text Available The nonnegligible propagation delay of acoustic signals causes spatiotemporal uncertainty that occasionally enables simultaneous, collision-free packet transmission among underwater nodes (UNs. These transmissions can be handled by efficiently managing the channel access of the UNs in the data-link layer. To this end, Geometric Spatial Reuse-TDMA (GSR-TDMA, a new TDMA-based MAC protocol, is designed for use in centralized, multihop underwater acoustic sensor networks (UASNs, and in this case all UNs are periodically scheduled after determining a geometric map according to the information on their location. The scheduling strategy increases the number of UNs that send packets coincidentally via two subscheduling configurations (i.e., interhop and intrahop scheduling. Extensive simulations are used to investigate the reception success rate (RSR and the multihop delay (MHD of GSR-TDMA, and the results are compared to those of previous approaches, including C-MAC and HSR-TDMA. GSR-TDMA outperforms C-MAC; the RSR of GSR-TDMA is 15% higher than that of C-MAC, and the MHD of GSR-TDMA is 30% lower than that of C-MAC at the most. In addition, GSR-TDMA provides even better performance improvements over HSR-TDMA; the RSR of GSR-TDMA is 50% higher than that of HSR-TDMA, and the MHD of GSR-TDMA is an order of 102 lower than that of HSR-TDMA at the most.

  9. AN EFFICIENT MAC PROTOCOL BASED ON HYBRID SUPERFRAME FOR WIRELESS SENSOR NETWORKS

    Directory of Open Access Journals (Sweden)

    Ge Ma

    2009-07-01

    Full Text Available Designing low energy consumption, high efficiency Media Access Control (MAC protocols are one ofthe most important directions in wireless sensor networks (WSN. In this paper, we proposed a newcontention reserve MAC protocol, named CRMAC, under the inspiration of IEEE 802.15.4’s superframestructure. CRMAC is a MAC protocol suitable for intra-cluster WSN that combines the advantages ofcontention and schedule-based MAC protocols. We introduce the mechanism and superframe structure ofCRMAC in detail and verified the performance of this protocol through simulations. Our results showthat CRMAC performs better than IEEE 802.15.4 in energy consumption, system delay and networkthroughput. CRMAC is especially suitable for short packet transmission under low load networks, whichis the main situation in WSN.

  10. Experimental Evaluation of Simulation Abstractions for Wireless Sensor Network MAC Protocols

    Directory of Open Access Journals (Sweden)

    G. P. Halkes

    2010-01-01

    Full Text Available The evaluation of MAC protocols for Wireless Sensor Networks (WSNs is often performed through simulation. These simulations necessarily abstract away from reality in many ways. However, the impact of these abstractions on the results of the simulations has received only limited attention. Moreover, many studies on the accuracy of simulation have studied either the physical layer and per link effects or routing protocol effects. To the best of our knowledge, no other work has focused on the study of the simulation abstractions with respect to MAC protocol performance. In this paper, we present the results of an experimental study of two often used abstractions in the simulation of WSN MAC protocols. We show that a simple SNR-based reception model can provide quite accurate results for metrics commonly used to evaluate MAC protocols. Furthermore, we provide an analysis of what the main sources of deviation are and thereby how the simulations can be improved to provide even better results.

  11. SACRB-MAC: A High-Capacity MAC Protocol for Cognitive Radio Sensor Networks in Smart Grid.

    Science.gov (United States)

    Yang, Zhutian; Shi, Zhenguo; Jin, Chunlin

    2016-03-31

    The Cognitive Radio Sensor Network (CRSN) is considered as a viable solution to enhance various aspects of the electric power grid and to realize a smart grid. However, several challenges for CRSNs are generated due to the harsh wireless environment in a smart grid. As a result, throughput and reliability become critical issues. On the other hand, the spectrum aggregation technique is expected to play an important role in CRSNs in a smart grid. By using spectrum aggregation, the throughput of CRSNs can be improved efficiently, so as to address the unique challenges of CRSNs in a smart grid. In this regard, we proposed Spectrum Aggregation Cognitive Receiver-Based MAC (SACRB-MAC), which employs the spectrum aggregation technique to improve the throughput performance of CRSNs in a smart grid. Moreover, SACRB-MAC is a receiver-based MAC protocol, which can provide a good reliability performance. Analytical and simulation results demonstrate that SACRB-MAC is a promising solution for CRSNs in a smart grid.

  12. SACRB-MAC: A High-Capacity MAC Protocol for Cognitive Radio Sensor Networks in Smart Grid

    Directory of Open Access Journals (Sweden)

    Zhutian Yang

    2016-03-01

    Full Text Available The Cognitive Radio Sensor Network (CRSN is considered as a viable solution to enhance various aspects of the electric power grid and to realize a smart grid. However, several challenges for CRSNs are generated due to the harsh wireless environment in a smart grid. As a result, throughput and reliability become critical issues. On the other hand, the spectrum aggregation technique is expected to play an important role in CRSNs in a smart grid. By using spectrum aggregation, the throughput of CRSNs can be improved efficiently, so as to address the unique challenges of CRSNs in a smart grid. In this regard, we proposed Spectrum Aggregation Cognitive Receiver-Based MAC (SACRB-MAC, which employs the spectrum aggregation technique to improve the throughput performance of CRSNs in a smart grid. Moreover, SACRB-MAC is a receiver-based MAC protocol, which can provide a good reliability performance. Analytical and simulation results demonstrate that SACRB-MAC is a promising solution for CRSNs in a smart grid.

  13. HARVESTED ENERGY-ADAPTIVE MAC PROTOCOL FOR ENERGY HARVESTING IOT NETWORKS

    Directory of Open Access Journals (Sweden)

    Hyeong-Kyu Lee

    2015-12-01

    Full Text Available In energy harvesting IoT networks, an energy queue state of an IoT device will change dynamically and the number of IoT devices that transmit data to the IoT AP will vary in a frame. So we need a MAC protocol to adjust the frame length taking the amount of energy of IoT devices into consideration. Since the existing Framed slotted ALOHA (F-ALOHA Medium Access Control (MAC protocol utilizes the fixed frame size, the resource efficiency can be reduced. In this paper, we propose a Harvested Energy-adaptive Medium Access Control (HEMAC protocol where an IoT Access Point (AP allocates slots in accordance with the number of IoT devices that try to transmit data in a frame. The proposed HE-MAC protocol improves the resource efficiency of the F-ALOHA MAC protocol. We show that the resource efficiency of the HE-MAC protocol is superior to those of the F-ALOHA MAC protocol through simulations.

  14. Corrections to "Connectivity-Based Reliable Multicast MAC Protocol for IEEE 802.11 Wireless LANs"

    Directory of Open Access Journals (Sweden)

    Choi Woo-Yong

    2010-01-01

    Full Text Available We have found the errors in the throughput formulae presented in our paper "Connectivity-based reliable multicast MAC protocol for IEEE 802.11 wireless LANs". We provide the corrected formulae and numerical results.

  15. Evaluation of video transmission of MAC protocols in wireless sensor network

    Science.gov (United States)

    Maulidin, Mahmuddin, M.; Kamaruddin, L. M.; Elsaikh, Mohamed

    2016-08-01

    Wireless Sensor Network (WSN) is a wireless network which consists of sensor nodes scattered in a particular area which are used to monitor physical or environment condition. Each node in WSN is also scattered in sensor field, so an appropriate scheme of MAC protocol should have to develop communication link for data transferring. Video transmission is one of the important applications for the future that can be transmitted with low aspect in side of cost and also power consumption. In this paper, comparison of five different MAC WSN protocol for video transmission namely IEEE 802.11 standard, IEEE 802.15.4 standard, CSMA/CA, Berkeley-MAC, and Lightweight-MAC protocol are studied. Simulation experiment has been conducted in OMNeT++ with INET network simulator software to evaluate the performance. Obtained results indicate that IEEE 802.11 works better than other protocol in term of packet delivery, throughput, and latency.

  16. A concurrent access MAC protocol for cognitive radio ad hoc networks without common control channel

    Science.gov (United States)

    Timalsina, Sunil K.; Moh, Sangman; Chung, Ilyong; Kang, Moonsoo

    2013-12-01

    Cognitive radio ad hoc networks (CRAHNs) consist of autonomous nodes that operate in ad hoc mode and aim at efficient utilization of spectrum resources. Usually, the cognitive nodes in a CRAHN exploit a number of available channels, but these channels are not necessarily common to all nodes. Such a network environment poses the problem of establishing a common control channel (CCC) as there might be no channel common to all the network members at all. In designing protocols, therefore, it is highly desirable to consider the network environment with no CCC. In this article, we propose a MAC protocol called concurrent access MAC (CA-MAC) that operates in the network environment with no CCC. The two devices in a communication pair can communicate with each other even if they have only one common channel available. Therefore, the problems with CCC (such as channel saturation and denial of service attacks) can also be resolved. In CA-MAC, channel accesses are distributed over communication pairs, resulting in increased network connectivity. In addition, CA-MAC allows different communication pairs to access multiple channels concurrently. According to our performance study, CA-MAC provides higher network connectivity with shorter channel access delay compared to SYN-MAC, which is the conventional key MAC protocol for the network environment with no CCC, resulting in better network throughput.

  17. Adaptive low-power listening MAC protocol based on transmission rates.

    Science.gov (United States)

    Hwang, Kwang-il; Yi, Gangman

    2014-01-01

    Even though existing low-power listening (LPL) protocols have enabled ultra-low-power operation in wireless sensor networks (WSN), they do not address trade-off between energy and delay, since they focused only on energy aspect. However, in recent years, a growing interest in various WSN applications is requiring new design factors, such as minimum delay and higher reliability, as well as energy efficiency. Therefore, in this paper we propose a novel sensor multiple access control (MAC) protocol, transmission rate based adaptive low-power listening MAC protocol (TRA-MAC), which is a kind of preamble-based LPL but is capable of controlling preamble sensing cycle adaptively to transmission rates. Through experiments, it is demonstrated that TRA-MAC enables LPL cycle (LC) and preamble transmission length to adapt dynamically to varying transmission rates, compensating trade-off between energy and response time.

  18. A Multi-Channel Diversity Based MAC Protocol for Power-Constrained Cognitive Ad Hoc Networks

    CERN Document Server

    Wang, Yichen; Du, Qinghe; Zhang, Chao

    2011-01-01

    One of the major challenges in the medium access control (MAC) protocol design over cognitive Ad Hoc networks (CAHNs) is how to efficiently utilize multiple opportunistic channels, which vary dynamically and are subject to limited power resources. To overcome this challenge, in this paper we first propose a novel diversity technology called \\emph{Multi-Channel Diversity} (MCD), allowing each secondary node to use multiple channels simultaneously with only one radio per node under the upperbounded power. Using the proposed MCD, we develop a MCD based MAC (MCD-MAC) protocol, which can efficiently utilize available channel resources through joint power-channel allocation. Particularly, we convert the joint power-channel allocation to the Multiple-Choice Knapsack Problem, such that we can obtain the optimal transmission strategy to maximize the network throughput through dynamic programming. Simulation results show that our proposed MCD-MAC protocol can significantly increase the network throughput as compared to...

  19. CoR-MAC: Contention over Reservation MAC Protocol for Time-Critical Services in Wireless Body Area Sensor Networks.

    Science.gov (United States)

    Yu, Jeongseok; Park, Laihyuk; Park, Junho; Cho, Sungrae; Keum, Changsup

    2016-05-09

    Reserving time slots for urgent data, such as life-critical information, seems to be very attractive to guarantee their deadline requirements in wireless body area sensor networks (WBASNs). On the other hand, this reservation imposes a negative impact on performance for the utilization of a channel. This paper proposes a new channel access scheme referred to as the contention over reservation MAC (CoR-MAC) protocol for time-critical services in wireless body area sensor networks. CoR-MAC uses the dual reservation; if the reserved time slots are known to be vacant, other nodes can access the time slots by contention-based reservation to maximize the utilization of a channel and decrease the delay of the data. To measure the effectiveness of the proposed scheme against IEEE 802.15.4 and IEEE 802.15.6, we evaluated their performances with various performance indexes. The CoR-MAC showed 50% to 850% performance improvement in terms of the delay of urgent and time-critical data according to the number of nodes.

  20. A cross-layer duty cycle MAC protocol supporting a pipeline feature for wireless sensor networks.

    Science.gov (United States)

    Tong, Fei; Xie, Rong; Shu, Lei; Kim, Young-Chon

    2011-01-01

    Although the conventional duty cycle MAC protocols for Wireless Sensor Networks (WSNs) such as RMAC perform well in terms of saving energy and reducing end-to-end delivery latency, they were designed independently and require an extra routing protocol in the network layer to provide path information for the MAC layer. In this paper, we propose a new cross-layer duty cycle MAC protocol with data forwarding supporting a pipeline feature (P-MAC) for WSNs. P-MAC first divides the whole network into many grades around the sink. Each node identifies its grade according to its logical hop distance to the sink and simultaneously establishes a sleep/wakeup schedule using the grade information. Those nodes in the same grade keep the same schedule, which is staggered with the schedule of the nodes in the adjacent grade. Then a variation of the RTS/CTS handshake mechanism is used to forward data continuously in a pipeline fashion from the higher grade to the lower grade nodes and finally to the sink. No extra routing overhead is needed, thus increasing the network scalability while maintaining the superiority of duty-cycling. The simulation results in OPNET show that P-MAC has better performance than S-MAC and RMAC in terms of packet delivery latency and energy efficiency.

  1. An extended smart utilization medium access control (ESU-MAC) protocol for ad hoc wireless systems

    Science.gov (United States)

    Vashishtha, Jyoti; Sinha, Aakash

    2006-05-01

    The demand for spontaneous setup of a wireless communication system has increased in recent years for areas like battlefield, disaster relief operations etc., where a pre-deployment of network infrastructure is difficult or unavailable. A mobile ad-hoc network (MANET) is a promising solution, but poses a lot of challenges for all the design layers, specifically medium access control (MAC) layer. Recent existing works have used the concepts of multi-channel and power control in designing MAC layer protocols. SU-MAC developed by the same authors, efficiently uses the 'available' data and control bandwidth to send control information and results in increased throughput via decreasing contention on the control channel. However, SU-MAC protocol was limited for static ad-hoc network and also faced the busy-receiver node problem. We present the Extended SU-MAC (ESU-MAC) protocol which works mobile nodes. Also, we significantly improve the scheme of control information exchange in ESU-MAC to overcome the busy-receiver node problem and thus, further avoid the blockage of control channel for longer periods of time. A power control scheme is used as before to reduce interference and to effectively re-use the available bandwidth. Simulation results show that ESU-MAC protocol is promising for mobile, ad-hoc network in terms of reduced contention at the control channel and improved throughput because of channel re-use. Results show a considerable increase in throughput compared to SU-MAC which could be attributed to increased accessibility of control channel and improved utilization of data channels due to superior control information exchange scheme.

  2. In-home Power Line Communication Media Access Control Protocol Based on Collision Resolution

    Institute of Scientific and Technical Information of China (English)

    WANG Bo; HUANG Pei-wei; ZHONG You-ping; QI Ying-hao

    2009-01-01

    Most existing media access control (MAC) protocols in power line communication (PLC) networks just discard the colliding data packets when collision occurs. The collision deteriorates throughput and delay performance of system under high traffic conditions. This article presents a novel media access scheme with fast collision resolution for in-home power line networks. It works by first recognizing the colliding stations through detecting the inserted unique ID sequence ahead of data packets, then the source nodes retransmitting their packets immediately after the collision slot. The proposed protocol maintains the benefits of ALOHA systems. It needs no scheduling overhead and is suitable for bursty sources, such as multimedia data packets. Computer simulations have demonstrated that this approach can achieve high throughput due to its ability of resolving collisions.

  3. Efficient MAC Protocol for Hybrid Wireless Network with Heterogeneous Sensor Nodes

    Directory of Open Access Journals (Sweden)

    Md. Nasre Alam

    2016-01-01

    Full Text Available Although several Directional Medium Access Control (DMAC protocols have been designed for use with homogeneous networks, it can take a substantial amount of time to change sensor nodes that are equipped with an omnidirectional antenna for sensor nodes with a directional antenna. Thus, we require a novel MAC protocol for use with an intermediate wireless network that consists of heterogeneous sensor nodes equipped with either an omnidirectional antenna or a directional antenna. The MAC protocols that have been designed for use in homogeneous networks are not suitable for use in a hybrid network due to deaf, hidden, and exposed nodes. Therefore, we propose a MAC protocol that exploits the characteristics of a directional antenna and can also work efficiently with omnidirectional nodes in a hybrid network. In order to address the deaf, hidden, and exposed node problems, we define RTS/CTS for the neighbor (RTSN/CTSN and Neighbor Information (NIP packets. The performance of the proposed MAC protocol is evaluated through a numerical analysis using a Markov model. In addition, the analytical results of the MAC protocol are verified through an OPNET simulation.

  4. Characterizing the Interaction Between Routing and MAC Protocols in Ad-Hoc Networks

    Energy Technology Data Exchange (ETDEWEB)

    Barrett, C. L. (Christopher L.); Drozda, M. (Martin); Marathe, A. (Achla); Marathe, M. V. (Madhav V.)

    2002-01-01

    We empirically study the effect of mobility on the performance of protocols designed for wireless ad-hoc networks. An important objective is to study the interaction of the Routing and MAC layer protocols under different mobility parameters. We use three basic mobility models: grid mobility model, random waypoint model, and exponential correlated random model. The performance of protocols is measured in terms of (i) latency, (ii) throughput, (iii) number of packets received, (iv) long term fairness and (v) number of control packets at the MAC and routing layer level. Three different commonly studied routing protocols are used: AODV, DSR and LAR1. Similarly three well known MAC protocols are used: MACA, 802.1 1 and CSMA. Our main contribution is simulation based experiments coupled with rigorous statistical analysis to characterize the interaction of MAC layer protocols with routing layer protocols in ad-hoc networks. From the results, we can conclude the following: e No single MAC or Routing protocol dominated the other protocols in their class. Probably more interestingly, no MAURouting protocol combination was better than other combinations over all scenarios and response variables. 0 In general, it is not meaningful to speak about a MAC or a routing protocol in isolation. Presence of interaction leads to trade-offs between the amount of control packets generated by each layer. The results raise the possibility of improving the performance of a particular MAC layer protocol by using a cleverly designed routing protocol or vice-versa. Thus in order to improve the performanceof a communication network, it is important to study the entire protocol stack as a single algorithmic construct; optimizing individual layers in the seven layer OS1 stack will not yield performance improvements beyond a point. A methodological contribution of this paper is the use of statistical methods such as analysis of variance (ANOVA), to characterize the interaction between the protocols

  5. A DUAL RESERVATION CDMA-BASED MAC PROTOCOL WITH POWER CONTROL FOR AD HOC NETWORKS

    Institute of Scientific and Technical Information of China (English)

    Jia Min; Chen Huimin; Yuan Yuhua

    2007-01-01

    This paper proposes a new multi-channel Medium Access Control (MAC) protocol named as Dual Reservation Code Division Multiple Access (CDMA) based MAC protocol with Power Control (DRCPC). The code channel is divided into common channel, broadcast channel and several data channels. And dynamic power control mechanism is implemented to reduce near-far interference. Compared with IEEE 802.11 Distributed Coordination Function (DCF) protocol, the results show that the proposed mechanism improves the average throughput and limits the transmission delay efficiently.

  6. An Empirical Study and some Improvements of the MiniMac Protocol for Secure Computation

    DEFF Research Database (Denmark)

    Damgård, Ivan Bjerre; Lauritsen, Rasmus; Toft, Tomas

    2014-01-01

    suggest a modification of MiniMac that achieves increased parallelism at no extra communication cost. This gives an asymptotic improvement of the original protocol as well as an 8-fold speed-up of our implementation. We compare the resulting protocol to TinyOT for the case of secure computation in parallel...

  7. Industrial WSN Based on IR-UWB and a Low-Latency MAC Protocol

    Science.gov (United States)

    Reinhold, Rafael; Underberg, Lisa; Wulf, Armin; Kays, Ruediger

    2016-07-01

    Wireless sensor networks for industrial communication require high reliability and low latency. As current wireless sensor networks do not entirely meet these requirements, novel system approaches need to be developed. Since ultra wideband communication systems seem to be a promising approach, this paper evaluates the performance of the IEEE 802.15.4 impulse-radio ultra-wideband physical layer and the IEEE 802.15.4 Low Latency Deterministic Network (LLDN) MAC for industrial applications. Novel approaches and system adaptions are proposed to meet the application requirements. In this regard, a synchronization approach based on circular average magnitude difference functions (CAMDF) and on a clean template (CT) is presented for the correlation receiver. An adapted MAC protocol titled aggregated low latency (ALL) MAC is proposed to significantly reduce the resulting latency. Based on the system proposals, a hardware prototype has been developed, which proves the feasibility of the system and visualizes the real-time performance of the MAC protocol.

  8. TraPy-MAC: Traffic Priority Aware Medium Access Control Protocol for Wireless Body Area Network.

    Science.gov (United States)

    Ullah, Fasee; Abdullah, Abdul Hanan; Kaiwartya, Omprakash; Cao, Yue

    2017-06-01

    Recently, Wireless Body Area Network (WBAN) has witnessed significant attentions in research and product development due to the growing number of sensor-based applications in healthcare domain. Design of efficient and effective Medium Access Control (MAC) protocol is one of the fundamental research themes in WBAN. Static on-demand slot allocation to patient data is the main approach adopted in the design of MAC protocol in literature, without considering the type of patient data specifically the level of severity on patient data. This leads to the degradation of the performance of MAC protocols considering effectiveness and traffic adjustability in realistic medical environments. In this context, this paper proposes a Traffic Priority-Aware MAC (TraPy-MAC) protocol for WBAN. It classifies patient data into emergency and non-emergency categories based on the severity of patient data. The threshold value aided classification considers a number of parameters including type of sensor, body placement location, and data transmission time for allocating dedicated slots patient data. Emergency data are not required to carry out contention and slots are allocated by giving the due importance to threshold value of vital sign data. The contention for slots is made efficient in case of non-emergency data considering threshold value in slot allocation. Moreover, the slot allocation to emergency and non-emergency data are performed parallel resulting in performance gain in channel assignment. Two algorithms namely, Detection of Severity on Vital Sign data (DSVS), and ETS Slots allocation based on the Severity on Vital Sign (ETS-SVS) are developed for calculating threshold value and resolving the conflicts of channel assignment, respectively. Simulations are performed in ns2 and results are compared with the state-of-the-art MAC techniques. Analysis of results attests the benefit of TraPy-MAC in comparison with the state-of-the-art MAC in channel assignment in realistic medical

  9. An Analysis on Decentralized Adaptive MAC Protocols for Cognitive Radio Networks

    Institute of Scientific and Technical Information of China (English)

    Munam Ali Shah; Sijing Zhang; Carsten Maple

    2013-01-01

    The scarcity of bandwidth in the radio spectrum has become more vital since the demand for more and more wireless applications has increased.Most of the spectrum bands have been allocated although many studies have shown that these bands are significantly underutilized most of the time.The problem of unavailability of spectrum and inefficiency in its utilization has been smartly addressed by the cognitive radio (CR) technology which is an opportunistic network that senses the environment,observes the network changes,and then uses knowledge gained from the prior interaction with the network to make intelligent decisions by dynamically adapting their transmission characteristics.In this paper,some of the decentralized adaptive medium access control (MAC) protocols for CR networks have been critically analyzed,and a novel adaptive MAC protocol for CR networks,decentralized non-global MAC (DNG-MAC),has been proposed.The results show the DNG-MAC outperforms other CR-MAC protocols in termsof time and energy efficiency.

  10. Ada-MAC: An Adaptive MAC Protocol for Real-time and Reliable Health Monitoring,

    OpenAIRE

    Xia, Feng; Wang, Linqiang; Zhang, Daqiang; Zhang, Xue(Department of Physics, Liaoning Normal University, Dalian, 116029, China); Gao, Ruixia

    2013-01-01

    IEEE 802.15.4 is regarded as one of the most suitable communication protocols for cyber-physical applications of wireless sensor and actuator networks. This is because this protocol is able to achieve low-power and low-cost transmission in wireless personal area networks. But most cyber-physical systems (CPSs) require a degree of real-time and reliability from the underlying communication protocol. Some of them are stricter than the others. However, IEEE 802.15.4 protocol cannot provide relia...

  11. An Energy-Efficient Division-Frame MAC Protocol for Wireless Sensor Networks%用于无线传感器网络的高能效分帧MAC协议

    Institute of Scientific and Technical Information of China (English)

    张佳薇; 陈岩; 李明宝

    2013-01-01

    为进一步降低传感器节点闲置侦听导致的能量消耗,改进MAC (media access control)协议,提出了一种用于无线传感器网络的新型的节能的分帧MAC (division-frame MAC,DF-MAC)协议.DF-MAC通过设置多个分帧使传感器节点的侦听时间缩短,减少了与其它节点通信所需的能量.DF-MAC有2个主要特点:低占空比和低碰撞数.在DF-MAC中碰撞数被降到最小程度,节省了重发封包所需的能量.仿真结果表明,与现有的MAC协议相比,能量消耗更低.%In order to decrease the energy consumption in idle listening of each sensor node and improve MAC (media access control) protocol, a novel energy-efficient division-frame MAC (DF-MAC) protocol is proposed for wireless sensor networks. DF-MAC allows sensor nodes to reduce their listening time by setting multiple division-frames, which will then reduce the energy consumption in communications with other nodes. DF-MAC has two main advantages, i.e. low duty cycle and small number of collisions. The minimization of collisions number in DF-MAC can save the energy required by retransmission of corrupted packets. Simulation results show that DF-MAC outweighs existing MAC protocols in the aspect of energy consumption.

  12. Persistent RCSMA: A MAC Protocol for a Distributed Cooperative ARQ Scheme in Wireless Networks

    Directory of Open Access Journals (Sweden)

    J. Alonso-Zárate

    2008-05-01

    Full Text Available The persistent relay carrier sensing multiple access (PRCSMA protocol is presented in this paper as a novel medium access control (MAC protocol that allows for the execution of a distributed cooperative automatic retransmission request (ARQ scheme in IEEE 802.11 wireless networks. The underlying idea of the PRCSMA protocol is to modify the basic rules of the IEEE 802.11 MAC protocol to execute a distributed cooperative ARQ scheme in wireless networks in order to enhance their performance and to extend coverage. A closed formulation of the distributed cooperative ARQ average packet transmission delay in a saturated network is derived in the paper. The analytical equations are then used to evaluate the performance of the protocol under different network configurations. Both the accuracy of the analysis and the performance evaluation of the protocol are supported and validated through computer simulations.

  13. A network architecture for precision formation flying using the IEEE 802.11 MAC Protocol

    Science.gov (United States)

    Clare, Loren P.; Gao, Jay L.; Jennings, Esther H.; Okino, Clayton

    2005-01-01

    Precision Formation Flying missions involve the tracking and maintenance of spacecraft in a desired geometric formation. The strong coupling of spacecraft in formation flying control requires inter-spacecraft communication to exchange information. In this paper, we present a network architecture that supports PFF control, from the initial random deployment phase to the final formation. We show that a suitable MAC layer for the application protocol is IEEE's 802.11 MAC protocol. IEEE 802.11 MAC has two modes of operations: DCF and PCF. We show that DCF is suitable for the initial deployment phase while switching to PCF when the spacecraft are in formation improves jitter and throughput. We also consider the effect of routing on protocol performance and suggest when it is profitable to turn off route discovery to achieve better network performance.

  14. MAC-layer protocol for TCP fairness in Wireless Mesh Networks

    KAUST Repository

    Nawab, Faisal

    2012-08-01

    In this paper we study the interactions of TCP and IEEE 802.11 MAC in Wireless Mesh Networks (WMNs). We use a Markov chain to capture the behavior of TCP sessions, particularly the impact on network throughput performance due to the effect of queue utilization and packet relaying. A closed form solution is derived to numerically determine the throughput. Based on the developed model, we propose a distributed MAC protocol to alleviate the unfairness problem in WMNs. Our protocol uses the age of packet as a priority metric for packet scheduling. Simulation is conducted to validate our model and to illustrate the fairness characteristics of our proposed MAC protocol. We conclude that we can achieve fairness with only little impact on network capacity.

  15. A MAC protocol for medical monitoring applications of wireless body area networks.

    Science.gov (United States)

    Shu, Minglei; Yuan, Dongfeng; Zhang, Chongqing; Wang, Yinglong; Chen, Changfang

    2015-06-03

    Targeting the medical monitoring applications of wireless body area networks (WBANs), a hybrid medium access control protocol using an interrupt mechanism (I-MAC) is proposed to improve the energy and time slot utilization efficiency and to meet the data delivery delay requirement at the same time. Unlike existing hybrid MAC protocols, a superframe structure with a longer length is adopted to avoid unnecessary beacons. The time slots are mostly allocated to nodes with periodic data sources. Short interruption slots are inserted into the superframe to convey the urgent data and to guarantee the real-time requirements of these data. During these interruption slots, the coordinator can break the running superframe and start a new superframe. A contention access period (CAP) is only activated when there are more data that need to be delivered. Experimental results show the effectiveness of the proposed MAC protocol in WBANs with low urgent traffic.

  16. The Impact of Dynamic RTS Threshold Adjustment for IEEE 802.11 MAC Protocol

    Directory of Open Access Journals (Sweden)

    Mostafa Mjidi

    2009-01-01

    Full Text Available In recent years, wireless technologies and application received great attention. The Medium Access Control (MAC protocol is the main element that determines the efficiency in sharing the limited communication bandwidth of the wireless channel in wireless local area networks (WLANs. IEEE 802.11 introduced the optional RTS/CTS handshaking mechanism to address the hidden terminal problem as well as to reduces the chance of collision in case of higher node density and traffic. RTS Threshold (RT determines when RTS/CTS mechanism should be used and proved to be an important parameter for performance characteristics in data transmission. We first investigate to find a meaningful threshold value according to the network situation and determine the impact of using or disengaging the RTS/CTS optional mechanism and dynamically adjust the RTS Threshold to maximize data transmission. The results show a significant improvement over existing CSMA/CA and RTS/CTS schemes. Our adaptive scheme performed even better when data rate increases. We verify our proposed scheme both analytically and with extensive network simulation using ns-2.

  17. Novel low energy consumption MAC protocol for the wireless sensor networks%一种无线传感器网络MAC层能量有效算法

    Institute of Scientific and Technical Information of China (English)

    李延晓; 张月玲; 管桦; 刘东洋

    2012-01-01

    Because of the limited power supply of nodes, wireless sensor network energy efficiency research is gaining more and more attention. The energy consumption of the MAC layer is analyzed. Based on the S-MAC protocol and PD-MAC protocol a novel algorithm AP is proposed. In simulations, the proposed protocol is evaluated in comparison with S-MAC and PD-MAC in the aspects of energy efficiency and accuracy of packets sink received. The result shows that collision probability can be reduced reasonably; that energy consumption can be reduced in a better way and that the network longevity can be enhanced efficiently.%由于无线传感器网络节点自身携带电池的特殊性,其能量有效策略的研究越来越受到人们的关注.分析了无线传感器网络数据链路层能量消耗,在S-MAC和PD算法基础上,提出了新的AP算法.仿真结果表明,AP算法合理地减少了碰撞,提高了数据包接收准确度,改进了无线传感器网络的能量有效性,并有效延长了网络的生命周期.

  18. A Multi-Channel MAC Protocol For Wireless Hospital Sensor Networks

    CERN Document Server

    Slimane, Jamila Ben; Frikha, Mounir; Koubâa, Anis

    2008-01-01

    Both IEEE 802.15.4 and 802.15.4a standards allow for dynamic channel allocation and use of multiple channels available at their physical layers but its MAC protocols are designed only for single channel. Also, sensor's transceivers such as CC2420 provide multiple channels and channel switch latency of CC2420 transceiver is very short just about 200 micro seconds. In order to enhance both energy efficiency and to shorten end to end delay, we propose, in this report, a new MAC protocol allowing multi-channel allocation for 802.15.4a compliant devices.

  19. An analytical model for Energy Consumption in Y-MAC Protocol

    Directory of Open Access Journals (Sweden)

    Ramchand V

    2012-01-01

    Full Text Available This paper presents an analytical model for estimating energy consumption in Y-MAC protocol for Wireless Sensor Networks (WSN. This protocol has been proposed to reduce the energy consumption of a node when involved in unicast or broadcast transmission of frames. In WSN a node consumes energy in transmitting and receiving of data, listening transmissions of other nodes, and in sleep mode. Therefore, energy consumption of a node has been estimated by adding up the energy consumed in each of the above activities. This has been achieved by estimating the time spent in each activity by a node. The protocol has been simulated using MATLAB. The simulation results show comparable energy savings as compared to Y-MAC protocol, therefore, the model validates the existing protocol.

  20. Clustering and OFDMA-based MAC protocol (COMAC for vehicular ad hoc networks

    Directory of Open Access Journals (Sweden)

    Abdel Hafeez Khalid

    2011-01-01

    Full Text Available Abstract The IEEE community is working on the wireless access in vehicular environments as a main technology for vehicular ad hoc networks. The medium access control (MAC protocol of this system known as IEEE 802.11p is based on the distributed coordination function (DCF of the IEEE 802.11 and enhanced DCF of the IEEE 802.11e that have low performance especially in high-density networks with nodes of high mobility. In this paper, we propose a novel MAC protocol where nodes dynamically organize themselves into clusters. Cluster heads are elected based on their stability on the road with minimal overhead since all clustering information is embedded in control channel's safety messages. The proposed MAC protocol is adaptable to drivers' behavior on the road and has learning mechanism for predicting the future speed and position of all cluster members using the fuzzy logic inference system. By using OFDMA, each cluster will use a set of subcarriers that are different from the neighboring clusters to eliminate the hidden terminal problem. Increasing the system reliability, reducing the time delay for vehicular safety applications and efficiently clustering vehicles in highly dynamic and dense networks in a distributed manner are the main contributions of our proposed MAC protocol.

  1. Experimental Evaluation of Simulation Abstractions for Wireless Sensor Network MAC Protocols

    NARCIS (Netherlands)

    Halkes, G.P.; Langendoen, K.G.

    2010-01-01

    The evaluation ofMAC protocols forWireless Sensor Networks (WSNs) is often performed through simulation. These simulations necessarily abstract away from reality inmany ways. However, the impact of these abstractions on the results of the simulations has received only limited attention. Moreover, ma

  2. Implantable body sensor network MAC protocols using wake-up radio - Evaluation in animal tissue

    NARCIS (Netherlands)

    Ramachandran, V.R.K.; Zwaag, van der Berend Jan; Meratnia, Nirvana; Havinga, Paul

    2015-01-01

    Applications of implantable sensor networks in the health-care industry have increased tremendously over the last decade. There are different types of medium access control (MAC) protocols that are designed for implantable body sensor networks, using different physical layer technologies such as nar

  3. Towards Improving the Quality of Present MAC Protocols for LECIM Systems

    Directory of Open Access Journals (Sweden)

    Mohammad Arif Siddiqui

    2016-06-01

    Full Text Available Wireless networking system is quickly growing in the field of communication technology due to its usefulness and huge applications. To make the system more effective to the users its lower energy consumption, security, reliability and lower cost issues must be considered under any circumstances. Low energy wireless is exceedingly required because the sensors are frequently located where mains power and network infrastructure are not reliably available. The recent development of Low Energy Critical Infrastructure Monitoring (LECIM has vast applications including: Water leak detection, Bridge/structural integrity monitoring, Oil & gas pipeline monitoring, electric plant monitoring, public transport tracking, Cargo container monitoring, Railroad condition monitoring, Traffic congestion monitoring, Border surveillance, Medical alert for at-risk populations and many more. This proposal Low Energy Critical Infrastructure Monitoring (LECIM is proposed by the Task Group 4k under IEEE P802.15 WPAN. Although many issues related to its quality are involved, but several Media Access Control (MAC protocols with different objectives were proposed for LECIM. In this research paper, issues related to energy consumption and wastage in LECIM system, energy savings mechanism, relevant energy conscious MAC protocols have been briefly studied and analyzed. Science Direct, Elsevier, Springer, IEEE Explore, Google Scholar and Wiley digital Library databases were used to search for articles related to the existing MAC protocols well suited for LECIM system. Finally, some ideas have been proposed towards developing energy efficient MAC protocol for LECIM applications in order to fulfill and satisfy the major issues of LECIM quality.

  4. Implantable Body Sensor Network MAC Protocols Using Wake-up Radio – Evaluation in Animal Tissue

    NARCIS (Netherlands)

    Karuppiah Ramachandran, Vignesh Raja; van der Zwaag, B.J.; Meratnia, Nirvana; Havinga, Paul J.M.

    Applications of implantable sensor networks in the health-care industry have increased tremendously over the last decade. There are different types of medium access control (MAC) protocols that are designed for implantable body sensor networks, using different physical layer technologies such as

  5. Fast Oblivious AES A Dedicated application of the MiniMac protocol

    DEFF Research Database (Denmark)

    Zakarias, Rasmus Winther; Damgård, Ivan Bjerre

    2015-01-01

    ]. They presented an optimized implementation of the so-called MiniMac protocol [DZ13] that runs in the pre-processing model, and applied this to a binary AES circuit. In this paper we de- scribe how to dedicate the pre-processing to the structure of AES, which improves significantly the throughput and latency...

  6. A Survey of MAC Protocols for Cognitive Radio Body Area Networks

    Science.gov (United States)

    Bhandari, Sabin; Moh, Sangman

    2015-01-01

    The advancement in electronics, wireless communications and integrated circuits has enabled the development of small low-power sensors and actuators that can be placed on, in or around the human body. A wireless body area network (WBAN) can be effectively used to deliver the sensory data to a central server, where it can be monitored, stored and analyzed. For more than a decade, cognitive radio (CR) technology has been widely adopted in wireless networks, as it utilizes the available spectra of licensed, as well as unlicensed bands. A cognitive radio body area network (CRBAN) is a CR-enabled WBAN. Unlike other wireless networks, CRBANs have specific requirements, such as being able to automatically sense their environments and to utilize unused, licensed spectra without interfering with licensed users, but existing protocols cannot fulfill them. In particular, the medium access control (MAC) layer plays a key role in cognitive radio functions, such as channel sensing, resource allocation, spectrum mobility and spectrum sharing. To address various application-specific requirements in CRBANs, several MAC protocols have been proposed in the literature. In this paper, we survey MAC protocols for CRBANs. We then compare the different MAC protocols with one another and discuss challenging open issues in the relevant research. PMID:25903551

  7. A simulation study of TaMAC protocol using network simulator 2.

    Science.gov (United States)

    Ullah, Sana; Kwak, Kyung Sup

    2012-10-01

    A Wireless Body Area Network (WBAN) is expected to play a significant role in future healthcare system. It interconnects low-cost and intelligent sensor nodes in, on, or around a human body to serve a variety of medical applications. It can be used to diagnose and treat patients with chronic diseases such as hypertensions, diabetes, and cardiovascular diseases. The lightweight sensor nodes integrated in WBAN require low-power operation, which can be achieved using different optimization techniques. We introduce a Traffic-adaptive MAC protocol (TaMAC) for WBAN that supports dual wakeup mechanisms for normal, emergency, and on-demand traffic. In this letter, the TaMAC protocol is simulated using a well-known Network Simulator 2 (NS-2). The problem of multiple emergency nodes is solved using both wakeup radio and CSMA/CA protocol. The power consumption, delay, and throughput performance are closely compared with beacon-enabled IEEE 802.15.4 MAC protocol using extensive simulations.

  8. Fast Oblivious AES A Dedicated application of the MiniMac protocol

    DEFF Research Database (Denmark)

    Zakarias, Rasmus Winther; Damgård, Ivan Bjerre

    2015-01-01

    ]. They presented an optimized implementation of the so-called MiniMac protocol [DZ13] that runs in the pre-processing model, and applied this to a binary AES circuit. In this paper we de- scribe how to dedicate the pre-processing to the structure of AES, which improves significantly the throughput and latency...

  9. A Survey of MAC Protocols for Cognitive Radio Body Area Networks.

    Science.gov (United States)

    Bhandari, Sabin; Moh, Sangman

    2015-04-20

    The advancement in electronics, wireless communications and integrated circuits has enabled the development of small low-power sensors and actuators that can be placed on, in or around the human body. A wireless body area network (WBAN) can be effectively used to deliver the sensory data to a central server, where it can be monitored, stored and analyzed. For more than a decade, cognitive radio (CR) technology has been widely adopted in wireless networks, as it utilizes the available spectra of licensed, as well as unlicensed bands. A cognitive radio body area network (CRBAN) is a CR-enabled WBAN. Unlike other wireless networks, CRBANs have specific requirements, such as being able to automatically sense their environments and to utilize unused, licensed spectra without interfering with licensed users, but existing protocols cannot fulfill them. In particular, the medium access control (MAC) layer plays a key role in cognitive radio functions, such as channel sensing, resource allocation, spectrum mobility and spectrum sharing. To address various application-specific requirements in CRBANs, several MAC protocols have been proposed in the literature. In this paper, we survey MAC protocols for CRBANs. We then compare the different MAC protocols with one another and discuss challenging open issues in the relevant research.

  10. Experimental Evaluation of Simulation Abstractions for Wireless Sensor Network MAC Protocols

    OpenAIRE

    2010-01-01

    The evaluation of MAC protocols for Wireless Sensor Networks (WSNs) is often performed through simulation. These simulations necessarily abstract away from reality in many ways. However, the impact of these abstractions on the results of the simulations has received only limited attention. Moreover, many studies on the accuracy of simulation have studied either the physical layer and per link effects or routing protocol effects. To the best of our knowledge, no other work has focused on the ...

  11. An energy-efficient MAC protocol using dynamic queue management for delay-tolerant mobile sensor networks.

    Science.gov (United States)

    Li, Jie; Li, Qiyue; Qu, Yugui; Zhao, Baohua

    2011-01-01

    Conventional MAC protocols for wireless sensor network perform poorly when faced with a delay-tolerant mobile network environment. Characterized by a highly dynamic and sparse topology, poor network connectivity as well as data delay-tolerance, delay-tolerant mobile sensor networks exacerbate the severe power constraints and memory limitations of nodes. This paper proposes an energy-efficient MAC protocol using dynamic queue management (EQ-MAC) for power saving and data queue management. Via data transfers initiated by the target sink and the use of a dynamic queue management strategy based on priority, EQ-MAC effectively avoids untargeted transfers, increases the chance of successful data transmission, and makes useful data reach the target terminal in a timely manner. Experimental results show that EQ-MAC has high energy efficiency in comparison with a conventional MAC protocol. It also achieves a 46% decrease in packet drop probability, 79% increase in system throughput, and 25% decrease in mean packet delay.

  12. Survey of the MAC Protocols on Underwater Acoustic Sensor Network%水声传感网MAC协议综述

    Institute of Scientific and Technical Information of China (English)

    周密; 崔勇; 徐兴福; 杨旭宁

    2011-01-01

    Nowadays the ocean plays an increasingly important role in the development of human society. As a basilic means to learn about the sea; underwater communication technology becomes a popular nodus in research. Different from the terrestrial wireless communication in channel characteristics and performance requirements;conventional wire less communication MAC( medium access control) does not apply to it MAC protocols for various underwater acoustic applications were continuously proposed. After outlining the characteristics of underwater acoustic sensor network and the designing standards of MAC;current control mode was divided into contention-based protocol and scheduling-based protocol according to the pattern by which the channel was accessed. The contention-based protocols were further divi ded into random access and collision avoidance according to their modes of dealing with collision; while scheduling-based ones into dynamic allocation and static allocation according to dynamics of channel allocation. Under this classification; the design idea and primary mechanism of current main protocols were described; their performance differences were discussed such as energy efficiency;channel utilization and throughput;and a new development direction was presented for the improvement of the MAC protocols.%海洋在人类发展中扮演着越来越重要的角色.水下通信技术作为人类认识海洋的重要手段,成为研究界的热点与难点.由于水下通信技术有不同于陆地无线通信的信道特点和性能要求,传统无线通信MAC(medium accesscontrol)协议难以直接应用于水声通信,因此相继提出针对各种应用场景的水声MAC协议.在简述水声传感网(Underwater Acoustic Sensor Network,UWASN)特点和MAC协议设计准则后,根据信道获取方式将当前典型协议分为基于竞争和基于调度两大类.根据冲突处置方式进一步将基于竞争的协议分为随机多址和冲突避免,

  13. A Very Low Power MAC (VLPM Protocol for Wireless Body Area Networks

    Directory of Open Access Journals (Sweden)

    Kyung Sup Kwak

    2011-03-01

    Full Text Available Wireless Body Area Networks (WBANs consist of a limited number of battery operated nodes that are used to monitor the vital signs of a patient over long periods of time without restricting the patient’s movements. They are an easy and fast way to diagnose the patient’s status and to consult the doctor. Device as well as network lifetime are among the most important factors in a WBAN. Prolonging the lifetime of the WBAN strongly depends on controlling the energy consumption of sensor nodes. To achieve energy efficiency, low duty cycle MAC protocols are used, but for medical applications, especially in the case of pacemakers where data have time-limited relevance, these protocols increase latency which is highly undesirable and leads to system instability. In this paper, we propose a low power MAC protocol (VLPM based on existing wakeup radio approaches which reduce energy consumption as well as improving the response time of a node. We categorize the traffic into uplink and downlink traffic. The nodes are equipped with both a low power wake-up transmitter and receiver. The low power wake-up receiver monitors the activity on channel all the time with a very low power and keeps the MCU (Micro Controller Unit along with main radio in sleep mode. When a node [BN or BNC (BAN Coordinator] wants to communicate with another node, it uses the low-power radio to send a wakeup packet, which will prompt the receiver to power up its primary radio to listen for the message that follows shortly. The wake-up packet contains the desired node’s ID along with some other information to let the targeted node to wake-up and take part in communication and let all other nodes to go to sleep mode quickly. The VLPM protocol is proposed for applications having low traffic conditions. For high traffic rates, optimization is needed. Analytical results show that the proposed protocol outperforms both synchronized and unsynchronized MAC protocols like T-MAC, SCP-MAC, B-MAC

  14. A very low power MAC (VLPM) protocol for Wireless Body Area Networks.

    Science.gov (United States)

    Ullah, Niamat; Khan, Pervez; Kwak, Kyung Sup

    2011-01-01

    Wireless Body Area Networks (WBANs) consist of a limited number of battery operated nodes that are used to monitor the vital signs of a patient over long periods of time without restricting the patient's movements. They are an easy and fast way to diagnose the patient's status and to consult the doctor. Device as well as network lifetime are among the most important factors in a WBAN. Prolonging the lifetime of the WBAN strongly depends on controlling the energy consumption of sensor nodes. To achieve energy efficiency, low duty cycle MAC protocols are used, but for medical applications, especially in the case of pacemakers where data have time-limited relevance, these protocols increase latency which is highly undesirable and leads to system instability. In this paper, we propose a low power MAC protocol (VLPM) based on existing wakeup radio approaches which reduce energy consumption as well as improving the response time of a node. We categorize the traffic into uplink and downlink traffic. The nodes are equipped with both a low power wake-up transmitter and receiver. The low power wake-up receiver monitors the activity on channel all the time with a very low power and keeps the MCU (Micro Controller Unit) along with main radio in sleep mode. When a node [BN or BNC (BAN Coordinator)] wants to communicate with another node, it uses the low-power radio to send a wakeup packet, which will prompt the receiver to power up its primary radio to listen for the message that follows shortly. The wake-up packet contains the desired node's ID along with some other information to let the targeted node to wake-up and take part in communication and let all other nodes to go to sleep mode quickly. The VLPM protocol is proposed for applications having low traffic conditions. For high traffic rates, optimization is needed. Analytical results show that the proposed protocol outperforms both synchronized and unsynchronized MAC protocols like T-MAC, SCP-MAC, B-MAC and X-MAC in terms

  15. Building an Energy-Efficient Prediction S-MAC Protocol for Wireless Networks

    Directory of Open Access Journals (Sweden)

    Mahmoud Abdel-Aziz El-Sakhawy Othman

    2010-12-01

    Full Text Available With the rapid development of wireless networking and micro-electro-mechanical systems (MEMS, wireless sensor networks (WSNs have been immerged. WSNs consist of large amount of small, low-end, resource constrained devices, called sensors. Since sensor nodes are usually intended to be deployed in unattended or even hostile environments, it is almost impossible to recharge or replace their batteries. One of the most important research issues in the wireless sensor networks is to extend the network lifetime by energy efficient battery management. So, there are a lot of approaches that are designed to reduce the power consumption of the wireless sensor nodes. In this paper; a new protocol named "prediction S-MAC protocol" is proposed to reduce the power consumption of the wireless sensor nodes and to improve their performance compared to the previous S-MAC protocols.

  16. An adaptive OFDMA-based MAC protocol for underwater acoustic wireless sensor networks.

    Science.gov (United States)

    Khalil, Issa M; Gadallah, Yasser; Hayajneh, Mohammad; Khreishah, Abdallah

    2012-01-01

    Underwater acoustic wireless sensor networks (UAWSNs) have many applications across various civilian and military domains. However, they suffer from the limited available bandwidth of acoustic signals and harsh underwater conditions. In this work, we present an Orthogonal Frequency Division Multiple Access (OFDMA)-based Media Access Control (MAC) protocol that is configurable to suit the operating requirements of the underwater sensor network. The protocol has three modes of operation, namely random, equal opportunity and energy-conscious modes of operation. Our MAC design approach exploits the multi-path characteristics of a fading acoustic channel to convert it into parallel independent acoustic sub-channels that undergo flat fading. Communication between node pairs within the network is done using subsets of these sub-channels, depending on the configurations of the active mode of operation. Thus, the available limited bandwidth gets fully utilized while completely avoiding interference. We derive the mathematical model for optimal power loading and subcarrier selection, which is used as basis for all modes of operation of the protocol. We also conduct many simulation experiments to evaluate and compare our protocol with other Code Division Multiple Access (CDMA)-based MAC protocols.

  17. An Adaptive OFDMA-Based MAC Protocol for Underwater Acoustic Wireless Sensor Networks

    Directory of Open Access Journals (Sweden)

    Issa M. Khalil

    2012-06-01

    Full Text Available Underwater acoustic wireless sensor networks (UAWSNs have many applications across various civilian and military domains. However, they suffer from the limited available bandwidth of acoustic signals and harsh underwater conditions. In this work, we present an Orthogonal Frequency Division Multiple Access (OFDMA-based Media Access Control (MAC protocol that is configurable to suit the operating requirements of the underwater sensor network. The protocol has three modes of operation, namely random, equal opportunity and energy-conscious modes of operation. Our MAC design approach exploits the multi-path characteristics of a fading acoustic channel to convert it into parallel independent acoustic sub-channels that undergo flat fading. Communication between node pairs within the network is done using subsets of these sub-channels, depending on the configurations of the active mode of operation. Thus, the available limited bandwidth gets fully utilized while completely avoiding interference. We derive the mathematical model for optimal power loading and subcarrier selection, which is used as basis for all modes of operation of the protocol. We also conduct many simulation experiments to evaluate and compare our protocol with other Code Division Multiple Access (CDMA-based MAC protocols.

  18. An Adaptive OFDMA-Based MAC Protocol for Underwater Acoustic Wireless Sensor Networks

    Science.gov (United States)

    Khalil, Issa M.; Gadallah, Yasser; Hayajneh, Mohammad; Khreishah, Abdallah

    2012-01-01

    Underwater acoustic wireless sensor networks (UAWSNs) have many applications across various civilian and military domains. However, they suffer from the limited available bandwidth of acoustic signals and harsh underwater conditions. In this work, we present an Orthogonal Frequency Division Multiple Access (OFDMA)-based Media Access Control (MAC) protocol that is configurable to suit the operating requirements of the underwater sensor network. The protocol has three modes of operation, namely random, equal opportunity and energy-conscious modes of operation. Our MAC design approach exploits the multi-path characteristics of a fading acoustic channel to convert it into parallel independent acoustic sub-channels that undergo flat fading. Communication between node pairs within the network is done using subsets of these sub-channels, depending on the configurations of the active mode of operation. Thus, the available limited bandwidth gets fully utilized while completely avoiding interference. We derive the mathematical model for optimal power loading and subcarrier selection, which is used as basis for all modes of operation of the protocol. We also conduct many simulation experiments to evaluate and compare our protocol with other Code Division Multiple Access (CDMA)-based MAC protocols. PMID:23012517

  19. A new real-time ethernet MAC protocol for time-critical applications

    Institute of Scientific and Technical Information of China (English)

    沈钢; 许晓鸣; 蔡云泽; 何星; 张卫东

    2002-01-01

    The authors propose a new persistent transmission-based real-time Ethernet MAC protocol that provides a predictable upper bound for the delivery delay of real-time frames. Moreover, it is compatible with the protocol used by the existing Ethernet controllers for conventional datagram traffic and thus standard Ethernet stations can be used in the system without any modification. The paper describes the protocol in detail and analyses the maximum delivery delay for real-time traffic and the efficiency of the channel.

  20. Detecting and Preventing Beacon Replay Attacks in Receiver-Initiated MAC Protocols for Energy Efficient WSNs

    DEFF Research Database (Denmark)

    Di Mauro, Alessio; Fafoutis, Xenofon; Mödersheim, Sebastian Alexander

    2013-01-01

    In receiver-initiated MAC protocols for Wireless Sensor Networks (WSNs), communication is initiated by the receiver of the data through beacons containing the receiver's identity. In this paper, we consider the case of a network intruder that captures and replays such beacons towards legitimate...... nodes, pretending to have a fake identity within the network. To prevent this attack we propose RAP, a challenge-response authentication protocol that is able to detect and prevent the beacon replay attack. The effectiveness of the protocol is formally verified using OFMC and ProVerif. Furthermore, we...

  1. 基于TDMA与CDMA混合的传感器网络MAC协议%TDMA/CDMA Hybrid MAC Protocol for Wireless Sensor Network

    Institute of Scientific and Technical Information of China (English)

    古志春; 肖德琴

    2011-01-01

    An efficient MAC protocol is one of the keys for long-time working and high-performance communication of WSN.There are several mechanisms for wireless channel allocation, such as Contention-base Random Access, TDMA (Time Division Multiple Access), FDMA(Frequency Division Multiple Access) and CDMA(Code Division Multiple Access).According to WSN,the CSMA-based MAC protocol bas disadvantages like idle listening and collision; the TDMA-based and FDMA-based MAC protocol has low scalability problem; the CDMA-based MAC protocol has the problem of additional power consumption.After analyzing energy model of the pure TDMA, pure CDMA and hybrid TDMA/CDMA, the paper presented a hybrid TDMA/CDMA MAC protocol based on cluster,which can solve the low latency and the conflict with interference.The protocol proposes the cluster nodes use TDMA and the cluster heads use CDMA.MAC could achieve collision avoidance and low latency in clusters,and do not have to ensure high accuracy synchronization between each cluster, so that the scalability of the sensor network would be enhanced.%MAC协议是保证无线传感器网络正常运作、高效通信的关键.无线传感器网络的无线信道分配机制主要有随机竞争机制、TDMA机制、FDMA机制以及CDMA机制.基于随机竞争的MAC协议存在空闲侦听和数据碰撞等能耗问题;基于TDMA和FDMA的MAC协议存在扩展性差的问题;基于CDMA则存在较多额外能耗开销的问题.在分析纯TDMA、纯CDMA和TDMA/CDMA混合的能耗模型的基础上,提出了一种基于分簇的TDMA/CDMA混合的HCT-MAC协议,它较好地解决了低时延和冲突干扰问题,其簇内节点采用TDMA机制进行信道分配,避免碰撞串扰问题,从而实现低延迟快速上传数据;簇首节点则采用CDMA机制,避免多跳同步问题,增强可扩展性.

  2. 水声传感器网络中基于改进时分多址技术的MAC协议%W-MAC: a MAC protocol with modified time division multiple access for underwater acoustic sensor networks

    Institute of Scientific and Technical Information of China (English)

    熊鹏

    2011-01-01

    海洋信道信号传输条件恶劣,水声传感器网络(UASN)的媒体访问控制协议(MAC)要能可靠且有效的工作面临极大的挑战.针对水下分组转发高传输延时和延时的起伏特性,提出了一个利用改进时分多址技术的媒体访问控制协议(W-MAC).W-MAC通过简化的信号传输同步过程,利用“延缓时间”作为节点的实际数据传送时间,采用具有睡眠策略的监测时间来避免数据碰撞等一系列措施,使W-MAC协议在适应复杂的水下信号传送环境的同时,把能量开销限制在一个合理的水平.仿真实验表明,在水声信道条件下该协议可有效地改善网络性能.%Signal transmission conditions are very poor for ocean channel. It is a great challenge for Media Access Control (MAC) protocol to work reliably and effectively in Underwater Acoustic Sensor Networks ( UASN). Due to the long and changeful propagation delay, a new MAC with modified TDMA named W-MAC was proposed, which could adapt underwater environment through simplified synchronization process, the defer time to allocate transmitting of all nodes as well as the detection time with sleep scheme to prevent from data collision to decrease the overhead of energy. The simulation results show W-MAC is quite efficient when data traffic is high in underwater acoustic sensor network.

  3. An Enhanced Reservation-Based MAC Protocol for IEEE 802.15.4 Networks

    Science.gov (United States)

    Afonso, José A.; Silva, Helder D.; Macedo, Pedro; Rocha, Luis A.

    2011-01-01

    The IEEE 802.15.4 Medium Access Control (MAC) protocol is an enabling standard for wireless sensor networks. In order to support applications requiring dedicated bandwidth or bounded delay, it provides a reservation-based scheme named Guaranteed Time Slot (GTS). However, the GTS scheme presents some drawbacks, such as inefficient bandwidth utilization and support to a maximum of only seven devices. This paper presents eLPRT (enhanced Low Power Real Time), a new reservation-based MAC protocol that introduces several performance enhancing features in comparison to the GTS scheme. This MAC protocol builds on top of LPRT (Low Power Real Time) and includes various mechanisms designed to increase data transmission reliability against channel errors, improve bandwidth utilization and increase the number of supported devices. A motion capture system based on inertial and magnetic sensors has been used to validate the protocol. The effectiveness of the performance enhancements introduced by each of the new features is demonstrated through the provision of both simulation and experimental results. PMID:22163826

  4. Energy adaptive MAC protocol for IEEE 802.15.7 with energy harvesting

    Science.gov (United States)

    Wang, Hong-qiao; Chi, Xue-fen; Zhao, Lin-lin

    2016-09-01

    The medium access control (MAC) protocol for indoor visible light communication (VLC) with energy harvesting is explored in this paper. The unfairness of throughput exists among devices due to the significant difference of their energy harvesting rates which changes with distance, acceptance angle and the obstruction probability. We propose an energy harvesting model, a new obstruction probability model and an energy adaptive contention algorithm to overcome the unfairness problem. This device can adjust its contention window according to the energy harvesting rate. As a result, the device with lower energy harvesting rate can get shorter contention window to improve its transmission opportunity. Simulation results show that our MAC protocol can achieve a higher degree of fairness.

  5. Towards Power Efficient MAC Protocol for In-Body and On-Body Sensor Networks

    CERN Document Server

    Ullah, Sana; Kwak, Kyung Sup; 10.1007/978-3-642-01665-3_34

    2009-01-01

    This paper presents an empirical discussion on the design and implementation of a power-efficient Medium Access Control (MAC) protocol for in-body and on-body sensor networks. We analyze the performance of a beacon-enabled IEEE 802.15.4, PB-TDMA, and S-MAC protocols for on-body sensor networks. We further present a Traffic Based Wakeup Mechanism that utilizes the traffic patterns of the BAN Nodes (BNs) to accommodate the entire BSN traffic. To enable a logical connection between different BNs working on different frequency bands, a method called Bridging function is proposed. The Bridging function integrates all BNs working on different bands into a complete BSN.

  6. 802.15.4 MAC protocol applied to efficient energy consumption

    Directory of Open Access Journals (Sweden)

    Juan Miguel Hernández Ontiveros

    2010-05-01

    Full Text Available This work focused on the problem of finding a suitable medium access control protocol so that the nodes of a given cluster could communicate efficiently within their respective activity window. The nodes thus saved energy by turning off their transceivers during the time that they did not have to exchange information. This work’s main objective was to ensure that the nodes were mainly focused on energy efficiency and delivering packages, taking quality of service (QoS requirements into account and comparing their performance to an existing protocol called sensor medium access control (S-MAC. The parameters being compared were the time that the nodes were asleep, energy consumption and average delay. This work was completed by using the OPNET simulator tool (OPNET Modeler, version 11.5.A PL3, OPNET Technologies Company Inc. This approach greatly improved the “PCF + Sleep” performance proposed in this work over the earlier S-MAC.

  7. Enhancing MAC performance of DCF protocol for IEEE 802.11 wireless LANs

    Science.gov (United States)

    Choi, Woo-Yong

    2017-01-01

    The DCF (Distributed Coordination Function) is the basic MAC (Medium Access Control) protocol of IEEE 802.11 wireless LANs and compatible with various IEEE 802.11 PHY extensions. The performance of the DCF degrades exponentially as the number of nodes participating in the DCF transmission procedure increases. To deal with this problem, we propose a simple, however efficient modification of the DCF by which the performance of the DCF is greatly enhanced.

  8. A QoS guaranteeing MAC layer protocol for the "underdog" traffic

    Directory of Open Access Journals (Sweden)

    Paolini Christopher

    2011-01-01

    Full Text Available Abstract With the tremendous boom in the wireless local area network arena, there has been a phenomenal spike in the web traffic which has been triggered by the growing popularity of real-time multimedia applications. Towards this end, the IEEE 802.11e medium access control (MAC standard specifies a set of quality-of-service (QoS enhancement features to ensure QoS for these delay sensitive multimedia applications. Most of these features are unfair and inefficient from the perspective of low priority (non-real time traffic flows as they tend to starve the non-real time flows depriving them of appropriate channel access, hence throughput. To that extent, this article proposes a MAC protocol that ensures fairness in the overall network performance by still providing QoS for real-time traffic without starving the "underdog" or non-real-time flows. The article first presents analytical expressions supported by Matlab simulation results which highlight the performance drawbacks of biased protocols such as 802.11e. It then evaluates the efficiency of the proposed "fair MAC protocol" through extensive simulations conducted on the QualNet simulation platform. The simulation results validate the fairness aspect of the proposed scheme.

  9. Performance Analysis of a Cluster-Based MAC Protocol for Wireless Ad Hoc Networks

    Directory of Open Access Journals (Sweden)

    Jesús Alonso-Zárate

    2010-01-01

    Full Text Available An analytical model to evaluate the non-saturated performance of the Distributed Queuing Medium Access Control Protocol for Ad Hoc Networks (DQMANs in single-hop networks is presented in this paper. DQMAN is comprised of a spontaneous, temporary, and dynamic clustering mechanism integrated with a near-optimum distributed queuing Medium Access Control (MAC protocol. Clustering is executed in a distributed manner using a mechanism inspired by the Distributed Coordination Function (DCF of the IEEE 802.11. Once a station seizes the channel, it becomes the temporary clusterhead of a spontaneous cluster and it coordinates the peer-to-peer communications between the clustermembers. Within each cluster, a near-optimum distributed queuing MAC protocol is executed. The theoretical performance analysis of DQMAN in single-hop networks under non-saturation conditions is presented in this paper. The approach integrates the analysis of the clustering mechanism into the MAC layer model. Up to the knowledge of the authors, this approach is novel in the literature. In addition, the performance of an ad hoc network using DQMAN is compared to that obtained when using the DCF of the IEEE 802.11, as a benchmark reference.

  10. AN MAC PROTOCOL SUPPORTING MULTIPLE TRAFFIC OVER MOBILE AD HOC NETWORKS

    Institute of Scientific and Technical Information of China (English)

    TianHui; LiYingyang

    2003-01-01

    This letter presents the design and performance of a multi-channel MAC protocol that supports multiple traffics for IEEE 802.11 mobile ad-hoc networks.The dynamic channel selection scheme by receiver decision is implemented and the number of the data channel is independent of the network topology.The priority for real-time traffic is assured by the proposed adaptive back off algorithm and different IFS.The protocol is evaluated by simulation and the results have shown that it can support multiple traffics and the performance is better than the performance that IEEE 802.11 standard provides.

  11. AN MAC PROTOCOL SUPPORTING MULTIPLE TRAFFIC OVER MOBILE AD HOC NETWORKS

    Institute of Scientific and Technical Information of China (English)

    Tian Hui; Li Yingyang; Hu Jiandong; Zhang Ping

    2003-01-01

    This letter presents the design and performance of a multi-channel MAC protocol that supports multiple traffics for IEEE 802.11 mobile ad-hoc networks. The dynamic channel selection scheme by receiver decision is implemented and the number of the data channel is independent of the network topology. The priority for real-time traffic is assured by the proposed adaptive back off algorithm and different IFS. The protocol is evaluated by simulation and the results have shown that it can support multiple traffics and the performance is better than the performance that IEEE 802.11 standard provides.

  12. QTDMAC: MAC protocol for QoS support in MANET using smart antennas

    Institute of Scientific and Technical Information of China (English)

    ZHANG Ying-chao; GUAN Li-li

    2009-01-01

    Unlike directional antennas, smart antennas offer MANET (Mobile Ad hoc Net works) potential increases in their achievable throughput and capacity. Based on the development of smart antenna technology, we studied the MAC protocol for QoS support was studied, which becomes the hot issue in multimedia services. The protocol divides the channel into the data channel and the control channel, node sends forecast guarantee to compete the channel. And after completing the RTS / CTS handshake appointment, node is reserved for data transmission. Node can send Busy Tones to prevent the problem of the deafness nodes and hidden terminal. At last if the direct link between the sender and receiver has low quality and low rate, data packets may be delivered faster through a relay node. Through the analytical results, QTDMAC with the protocol IEEE802.1 and DMAC were compared. The QTDMAC protocol is proved the superiority in throughput and the real-time delay business.

  13. An Energy Efficient MAC Protocol for Multi-Hop Swallowable Body Sensor Networks

    Directory of Open Access Journals (Sweden)

    Lin Lin

    2014-10-01

    Full Text Available Swallowable body sensor networks (BSNs are composed of sensors which are swallowed by patients and send the collected data to the outside coordinator. These sensors are energy constraint and the batteries are difficult to be replaced. The medium access control (MAC protocol plays an important role in energy management. This paper investigates an energy efficient MAC protocol design for swallowable BSNs. Multi-hop communication is analyzed and proved more energy efficient than single-hop communication within the human body when the circuitry power is low. Based on this result, a centrally controlled time slotting schedule is proposed. The major workload is shifted from the sensors to the coordinator. The coordinator collects the path-loss map and calculates the schedules, including routing, slot assignment and transmission power. Sensor nodes follow the schedules to send data in a multi-hop way. The proposed protocol is compared with the IEEE 802.15.6 protocol in terms of energy consumption. The results show that it is more energy efficient than IEEE 802.15.6 for swallowable BSN scenarios.

  14. User profile based proportional share scheduling and mac protocol for manets

    CERN Document Server

    Monisha, J Hannah; 10.5121/ijdps.2012.3123

    2012-01-01

    Quality of Service(QoS) in Mobile Ad Hoc Networks (MANETs) though a challenge, becomes a necessity because of its applications in critical scenarios. Providing QoS for users belonging to various profiles and playing different roles, becomes the need of the hour. In this paper, we propose proportional share scheduling and MAC protocol (PS2-MAC) model. It classifies users based on their profile as High Profiled users (HP), Medium Profiled users (MP) and Low profiled users (LP) and assigns proportional weights. Service Differentiation for these three service classes is achieved through, rationed dequeuing algorithm, variable inter frame space, proportionate prioritized backoff timers and enhanced RTS/CTS control packets. Differentiated services is simulated in ns2 and results show that 9.5% control overhead is reduced in our proposed scheme than the existing scheme and results also justify that, differentiated services have been achieved for the different profiles of users with proportionate shares and thereby r...

  15. Design and Implementation of IEEE 802.15.4 Mac Protocol on FPGA

    CERN Document Server

    Bhat, Naagesh S

    2012-01-01

    The IEEE 802.15.4 is a wireless standard introduced for low power, low cost wireless communication with moderate data rates. In the next few years, it is expected that Low Rate Wireless Personal Area Networks (LR-WPAN) will be used in a wide variety of embedded applications, including home automation, industrial sensing and control, environmental monitoring and sensing. In these applications, numerous embedded devices running on batteries are distributed in an area communicating via wireless radios. This work presents a method which can be used for comparing current consumption of wireless data transfer embedded systems. This paper implements a small subset of the IEEE 802.15.4 protocol to achieve a point to point communication. The implemented protocol uses 802.15.4 MAC compliant data and acknowledgment packets. Current consumption is measured while doing one data packet transmission. Measurements are compared with existing work. IEEE 802.15.4 protocol implementation is done using Verilog language. Code impl...

  16. PA-MAC:A Passive Asynchronous MAC Protocol for Low Duty-Cycled Wireless Sensor Networks%PA-MAC:一种被动的异步低占空比无线传感器网络MAC协议

    Institute of Scientific and Technical Information of China (English)

    唐震洲; 施晓秋; 金可仲

    2011-01-01

    空闲侦听是无线传感器网络能耗的主要原因之一,而占空比机制是减少空闲侦听能量损耗最主要的方法之一.提出了一种新的无线传感器网络异步MAC协议,称为PA-MAC(Passive Asynchronous MAC),即被动异步MAC.PA-MAC通过采用接收方发起数据传输机制、异步占空比机制以及节点唤醒时间估计机制,降低了节点的工作占空比,提高了网络的能量有效性.在NS2网络仿真平台上对PA-MAC的性能进行了评估.仿真结果表明,在保持网络性能的前提下,PA-MAC能够进一步降低节点工作的占空比,进而减少节点的能耗.%The problem of idle listening is one of the most concerned issues in wireless sensor networks, and the duty cycling mechanism is widely used to reduce energy consumption. We present a new asynchronous MAC protocol, called Passive-Asynchronous MAC (PA-MAC). PA-MAC uses receiver-initiated data transmission scheme, asynchronous duty cycling mechanism and awakening time estimation scheme to achieve low duty cycle and high energy efficiency. Simulations have been done to evaluate the performance of the proposed new protocol, by which we can find out that,on the premise of keeping the network performance,PA-MAC can further reduce the nodes' duty cycle ,thereby reduce the energy consumption.

  17. A Schedule-based Multi-channel MAC Protocol for Wireless Sensor Networks

    Directory of Open Access Journals (Sweden)

    Ilyoung Chong

    2010-10-01

    Full Text Available Due to the half-duplex property of the sensor radio and the broadcast nature of wireless medium, limited bandwidth remains a pressing issue for wireless sensor networks (WSNs. The design of multi-channel MAC protocols has attracted the interest of many researchers as a cost effective solution to meet the higher bandwidth demand for the limited bandwidth in WSN. In this paper, we present a scheduled-based multi-channel MAC protocol to improve network performance. In our protocol, each receiving node selects (schedules some timeslot(s, in which it may receive data from the intending sender(s. The timeslot selection is done in a conflict free manner, where a node avoids the slots that are already selected by others in its interference range. To minimize the conflicts during timeslot selection, we propose a unique solution by splitting the neighboring nodes into different groups, where nodes of a group may select the slots allocated to that group only. We demonstrate the effectiveness of our approach thorough simulations in terms of performance parameters such as aggregate throughput, packet delivery ratio, end-to-end delay, and energy consumption.

  18. Design and Performance Evaluation of a Distributed OFDMA-Based MAC Protocol for MANETs

    Directory of Open Access Journals (Sweden)

    Jaesung Park

    2014-01-01

    Full Text Available In this paper, we propose a distributed MAC protocol for OFDMA-based wireless mobile ad hoc multihop networks, in which the resource reservation and data transmission procedures are operated in a distributed manner. A frame format is designed considering the characteristics of OFDMA that each node can transmit or receive data to or from multiple nodes simultaneously. Under this frame structure, we propose a distributed resource management method including network state estimation and resource reservation processes. We categorize five types of logical errors according to their root causes and show that two of the logical errors are inevitable while three of them are avoided under the proposed distributed MAC protocol. In addition, we provide a systematic method to determine the advertisement period of each node by presenting a clear relation between the accuracy of estimated network states and the signaling overhead. We evaluate the performance of the proposed protocol in respect of the reservation success rate and the success rate of data transmission. Since our method focuses on avoiding logical errors, it could be easily placed on top of the other resource allocation methods focusing on the physical layer issues of the resource management problem and interworked with them.

  19. A Multi-hop Energy-efficient Sleeping MAC Protocol based on TDMA Scheduling for Wireless Mesh Sensor Networks

    Directory of Open Access Journals (Sweden)

    Qiang Fan

    2012-09-01

    Full Text Available Abstract—Based on Wireless Mesh Network (WMN theory, according to the characteristics of Wireless Sensor Network (WSN clustering topology, WSN and WMN are combined to construct Wireless Mesh Sensor Network (WMSN topology. In order to improve the performance of energy-efficiency, throughput and delay in WMSN, this paper designs a Multi-hop TDMA Energy-efficient Sleeping MAC (MT-MAC protocol and gives the performance simulation with MATLAB. In MT-MAC, a TDMA frame was divided into a number of time slots for sensor nodes in WMSN to send or receive data packets. As the simulation result shows, compared with SMAC protocol, MT-MAC not only saves 25% energy consumption of the network, but also decreases 45% latency of the whole network.

  20. MAC Protocol for Data Gathering in Wireless Sensor Networks with the Aid of Unmanned Aerial Vehicles

    Directory of Open Access Journals (Sweden)

    VLADUTA, A.-V.

    2016-05-01

    Full Text Available Data gathering in wireless sensor networks by employing unmanned aerial vehicles has been a subject of real interest in the recent years. While drones are seen as an efficient method of data gathering in almost any environment, wireless sensor networks are the key elements for generating data because they have low dimensions, improved flexibility, decreased power consumption and costs. This paper addresses the communication at the Medium Access Control (MAC layer between static deployed sensors and a moving drone whose unique role is to collect data from all sensors on its path. The most important part of the proposed protocol consists of prioritizing the sensors in such a manner that each of them has a fair chance to communicate with the drone. Simulations are performed in NS-2 and results demonstrate the capabilities of the proposed protocol.

  1. Probabilistic verification and evaluation of Backoff procedure of the WSN ECo-MAC protocol

    Directory of Open Access Journals (Sweden)

    Hafedh ZAYANI

    2010-05-01

    Full Text Available Communication protocols and techniques are often evaluated using simulation techniques. However, theuse of formal modeling and analysis techniques for verification and evaluation in particular for WirelessSensor Networks (WSN becomes a necessity. In this paper we present a formal analysis of the backoffprocedure integrated in the medium access control protocol named ECo-MAC designed for WSN. Wedescribe this backoff procedure in terms of discrete time Markov chains (DTMCs and evaluated usingthe well known probabilistic model checker PRISM. After checking the different invariants of theproposed model, we study the effect of contention window length (in number of time contention unit onthe acceptable number of simultaneous senders in a neighborhood of a given receiver. The obtainedquantitative results confirm those provided by the simulation using OPNET tool and justify the validity ofthe adopted value for the time contention unit TCU.

  2. Probabilistic verification and evaluation of Backoff procedure of the WSN ECo-MAC protocol

    CERN Document Server

    Zayani, Hafedh; Ayed, Rahma Ben; 10.5121/ijwmn.2010.2211

    2010-01-01

    Communication protocols and techniques are often evaluated using simulation techniques. However, the use of formal modeling and analysis techniques for verification and evaluation in particular for Wireless Sensor Networks (WSN) becomes a necessity. In this paper we present a formal analysis of the backoff procedure integrated in the medium access control protocol named ECo-MAC designed for WSN. We describe this backoff procedure in terms of discrete time Markov chains (DTMCs) and evaluated using the well known probabilistic model checker PRISM. After checking the different invariants of the proposed model, we study the effect of contention window length (in number of time contention unit) on the acceptable number of simultaneous senders in a neighborhood of a given receiver. The obtained quantitative results confirm those provided by the simulation using OPNET tool and justify the validity of the adopted value for the time contention unit TCU.

  3. A Service Differentiated MAC Protocol for OFDM/TDMA Wireless Systems

    Institute of Scientific and Technical Information of China (English)

    WANG Ying; ZHANG Ping

    2005-01-01

    This paper proposes a Service Differentiated-Dynamic Slotted Multiple Access (SD-DSMA) protocol with QoS guarantee. The Media Access Control (MAC) frame format is variable according to the traffic of uplink and downlink and the traffic of control and data. In addition, the services are divided into two categories, Guaranteed Bandwidth (GB) and Best Effort (BE). Uplink control message slots are designed for the GB users to reduce contention. Taking into consideration the techniques in physical layer, a two-Dimensional Radio Resource Allocation (2-D RRA) method is proposed. The 2-D RRA is an efficient way to allocate radio resources for multi-cell, multi-user OFDM/TDMA system as it takes into consideration both the channel condition and the co-channel interference. The piggyback mechanism and fair scheduling algorithm are adopted for GB services, and the max C/I scheduling algorithm is used for BE services. The simulation results show that the proposed MAC protocol has better performance in terms of delay, probability of successful access request.

  4. Low Duty-Cycling MAC Protocol for Low Data-Rate Medical Wireless Body Area Networks

    Directory of Open Access Journals (Sweden)

    Chongqing Zhang

    2017-05-01

    Full Text Available Wireless body area networks (WBANs are severely energy constrained, and how to improve the energy efficiency so as to prolong the network lifetime as long as possible is one of the most important goals of WBAN research. Low data-rate WBANs are promising to cut down the energy consumption and extend the network lifetime. Considering the characteristics and demands of low data-rate WBANs, a low duty-cycling medium access control (MAC protocol is specially designed for this kind of WBAN in this paper. Longer superframes are exploited to cut down the energy consumed on the transmissions and receptions of redundant beacon frames. Insertion time slots are embedded into the inactive part of a superframe to deliver the frames and satisfy the quality of service (QoS requirements. The number of the data subsections in an insertion time slot can be adaptively adjusted so as to accommodate low data-rate WBANs with different traffic. Simulation results show that the proposed MAC protocol performs well under the condition of low data-rate monitoring traffic.

  5. Low Duty-Cycling MAC Protocol for Low Data-Rate Medical Wireless Body Area Networks

    Science.gov (United States)

    Zhang, Chongqing; Wang, Yinglong; Liang, Yongquan; Shu, Minglei; Zhang, Jinquan; Ni, Lina

    2017-01-01

    Wireless body area networks (WBANs) are severely energy constrained, and how to improve the energy efficiency so as to prolong the network lifetime as long as possible is one of the most important goals of WBAN research. Low data-rate WBANs are promising to cut down the energy consumption and extend the network lifetime. Considering the characteristics and demands of low data-rate WBANs, a low duty-cycling medium access control (MAC) protocol is specially designed for this kind of WBAN in this paper. Longer superframes are exploited to cut down the energy consumed on the transmissions and receptions of redundant beacon frames. Insertion time slots are embedded into the inactive part of a superframe to deliver the frames and satisfy the quality of service (QoS) requirements. The number of the data subsections in an insertion time slot can be adaptively adjusted so as to accommodate low data-rate WBANs with different traffic. Simulation results show that the proposed MAC protocol performs well under the condition of low data-rate monitoring traffic. PMID:28509849

  6. An Energy-Efficient MAC Protocol Using Dynamic Queue Management for Delay-Tolerant Mobile Sensor Networks

    Directory of Open Access Journals (Sweden)

    Yugui Qu

    2011-02-01

    Full Text Available Conventional MAC protocols for wireless sensor network perform poorly when faced with a delay-tolerant mobile network environment. Characterized by a highly dynamic and sparse topology, poor network connectivity as well as data delay-tolerance, delay-tolerant mobile sensor networks exacerbate the severe power constraints and memory limitations of nodes. This paper proposes an energy-efficient MAC protocol using dynamic queue management (EQ-MAC for power saving and data queue management. Via data transfers initiated by the target sink and the use of a dynamic queue management strategy based on priority, EQ-MAC effectively avoids untargeted transfers, increases the chance of successful data transmission, and makes useful data reach the target terminal in a timely manner. Experimental results show that EQ-MAC has high energy efficiency in comparison with a conventional MAC protocol. It also achieves a 46% decrease in packet drop probability, 79% increase in system throughput, and 25% decrease in mean packet delay.

  7. DLD-MAC:A Diffserv-based Low-delay MAC Protocol for WSNs%DLD-MAC:一种区分服务的低时延传感器网络MAC协议

    Institute of Scientific and Technical Information of China (English)

    舒俊浩; 白光伟; 沈航

    2012-01-01

    针对现有无线传感器网络MAC协议不能提供区分服务和传输时廷较大的问题,在经典多跳传输协议DW-MAC的基础上,提出了一种具有区分服务功能的低时延MAC协议—DLD-MAC(Diffserv-based Low-Delay MAC).其基本思路是让高优先级数据选择更小的竞争窗口,以降低时延和能耗.Markov建模分析表明,DLD-MAC能对不同优先级的业务流进行很好的服务区分,而且相较于传统的无线传感器网络MAC协议,其在时延性能上有显著优势,能更有效地保障服务质量.%Considering that most of the existing MAC protocols in wireless sensor networks do not support any priority scheme,this paper proposed a novel,Diffserv-based low-delay MAC mechanismCDLD-MAC),on the basis of the existing DW-MAC protocol. The main idea is that, by introducing differentiated services, the high priority data chooses smaller back-off window, so that it can achieve much more chance to be delivered, and its packet transmission latency and energy consumption can be reduced significantly compared with low priority data. On the other hand, a Markov chain model was designed in this work, to analyze and evaluate the mechanism performance. Our analytical analyses show that the proposed DLD-MAC can effectively make the high priority data achieve higher QoS over the low priority data, and achieve much lower transmission latency than traditional MAC protocol as well,which is adequate to serve delay-sensitive data flow.

  8. A Wireless Video Transmission Scheme Based on MAC-independent Opportunistic Routing &Encoding Protocol

    Directory of Open Access Journals (Sweden)

    Yong Liu

    2010-11-01

    Full Text Available It is a tremendous challenge to transmit real-time video streams over wireless sensor network because of the poor wireless communication conditions and the high requirements of video transmission. The opportunistic routing protocol can take advantage of the broadcast nature of wireless communication and can improve transfer throughput significantly. But the bigger size of transmission unit also increases the end-to-end delay at the same time. In order to overcome this problem and improve the real-time video transmission quality in wireless video sensor network, we propose a source adaptive frame discard algorithm for MAC-independent Opportunistic Routing & Encoding (MORE Protocol in this paper. In our approach, the historical transmission delay is recorded to estimate current network transmission rate. Based on the video deadline, frames predicted to be delayed are discarded adaptively in the source node to get better overall video quality. In some practice application scenarios, there are usually need to deliver multiple video streams over multi-hop wireless network. It can’t work effectively with the originally MORE protocol in such scenarios. Furthermore, we modify the MORE protocol and design an adaptive scheme to support multiple video streams over multi-hop wireless video sensor network in this paper. The simulation results show that our algorithm can reduce frame loss rate and improve video quality significantly.

  9. Two-stage coordination multi-radio multi-channel mac protocol for wireless mesh networks

    CERN Document Server

    Zhao, Bingxuan

    2011-01-01

    Within the wireless mesh network, a bottleneck problem arises as the number of concurrent traffic flows (NCTF) increases over a single common control channel, as it is for most conventional networks. To alleviate this problem, this paper proposes a two-stage coordination multi-radio multi-channel MAC (TSC-M2MAC) protocol that designates all available channels as both control channels and data channels in a time division manner through a two-stage coordination. At the first stage, a load balancing breadth-first-search-based vertex coloring algorithm for multi-radio conflict graph is proposed to intelligently allocate multiple control channels. At the second stage, a REQ/ACK/RES mechanism is proposed to realize dynamical channel allocation for data transmission. At this stage, the Channel-and-Radio Utilization Structure (CRUS) maintained by each node is able to alleviate the hidden nodes problem; also, the proposed adaptive adjustment algorithm for the Channel Negotiation and Allocation (CNA) sub-interval is ab...

  10. A hybrid MAC protocol design for energy-efficient very-high-throughput millimeter wave, wireless sensor communication networks

    Science.gov (United States)

    Jian, Wei; Estevez, Claudio; Chowdhury, Arshad; Jia, Zhensheng; Wang, Jianxin; Yu, Jianguo; Chang, Gee-Kung

    2010-12-01

    This paper presents an energy-efficient Medium Access Control (MAC) protocol for very-high-throughput millimeter-wave (mm-wave) wireless sensor communication networks (VHT-MSCNs) based on hybrid multiple access techniques of frequency division multiplexing access (FDMA) and time division multiplexing access (TDMA). An energy-efficient Superframe for wireless sensor communication network employing directional mm-wave wireless access technologies is proposed for systems that require very high throughput, such as high definition video signals, for sensing, processing, transmitting, and actuating functions. Energy consumption modeling for each network element and comparisons among various multi-access technologies in term of power and MAC layer operations are investigated for evaluating the energy-efficient improvement of proposed MAC protocol.

  11. Base station MAC with APRMA protocol for broadband multimedia ATM in micro/pico-cellular mobile networks

    DEFF Research Database (Denmark)

    Le, Khanh Hoang; Nielsen, Søren Nørskov; Dittmann, Lars

    1998-01-01

    The concept for a wireless ATM access system that enables seamless mobile connectivity to the B-ISDN is presented. It is based on small, low cost and intelligent base stations running a medium access control (MAC) protocol using adaptive packet reservation multiple access (APRMA). Both the princi...

  12. An Energy-efficient Rate Adaptive Media Access Protocol (RA-MAC for Long-lived Sensor Networks

    Directory of Open Access Journals (Sweden)

    Wen Hu

    2010-06-01

    Full Text Available We introduce an energy-efficient Rate Adaptive Media Access Control (RA-MAC algorithm for long-lived Wireless Sensor Networks (WSNs. Previous research shows that the dynamic and lossy nature of wireless communications is one of the major challenges to reliable data delivery in WSNs. RA-MAC achieves high link reliability in such situations by dynamically trading off data rate for channel gain. The extra gain that can be achieved reduces the packet loss rate which contributes to reduced energy expenditure through a reduced numbers of retransmissions. We achieve this at the expense of raw bit rate which generally far exceeds the application’s link requirement. To minimize communication energy consumption, RA-MAC selects the optimal data rate based on the estimated link quality at each data rate and an analytical model of the energy consumption. Our model shows how the selected data rate depends on different channel conditions in order to minimize energy consumption. We have implemented RA-MAC in TinyOS for an off-the-shelf sensor platform (the TinyNode on top of a state-of-the-art WSN Media Access Control Protocol, SCP-MAC, and evaluated its performance by comparing our implementation with the original SCP-MAC using both simulation and experiment.

  13. SmartGate: A MAC Protocol for Gateway Discovery in Clustered Ad-Hoc Networks

    Directory of Open Access Journals (Sweden)

    P. Venkateswaran

    2009-05-01

    Full Text Available In the absence of established infrastructure, Mobile Ad-Hoc Networks (MANETs can provide a fast and efficient way of communication among the nodes. In this paper, we present a MAC protocol with clusterhead and gateway selection algorithm. Clustering schemes are expected to achieve better scalability since most of the topology changes within a cluster are hidden from the rest of the network. Here, we use Node Identifier Packet (NIP to form the members of a cluster and depending upon several QoS metrics (e.g. bandwidth, battery life, SINR the clusterhead has been selected. For inter-cluster communication, we choose the gateway nodes. However, during the gateway selection procedure, we ensure that the maximum number of clusters that can be connected with the help of a single gateway does not exceed its tolerable overhead. This paper also provides the computational overhead of packet transfer for the gateway selection scheme. Simulation results show the performance of the protocol under different scenarios.

  14. Ensuring quality of service for multimedia services in two-step reservation MAC protocol for PLC access networks

    Science.gov (United States)

    Hrasnica, Halid; Lehnert, Ralf

    2004-09-01

    Recent and future communications networks have to provide QoS guarantees for a rapidly growing number of various telecommunication services, which can be ensured by application of an efficient MAC layer. Various communication technologies, such as cellular networks and PLC (PowerLine Communications) access networks, apply reservation MAC protocols, providing a good network utilization and realization of different QoS guarantees. In this investigation, we analyze possibilities for provision of QoS guarantees for various telecommunications services with a two-step reservation MAC protocol using per-packet reservation principle, which is proposed for application in broadband PLC access networks. Particularly, performance of the reservation procedure is analyzed to provide priority mechanisms which are necessary for realization of various telecommunications services ensuring the required QoS guarantees. Since the telephony, realized by the packet voice service, has the strongest QoS requirements among various telecommunications services, we analyze possibility for its realization within the two-step MAC protocol. It can be concluded that the packet voice can be efficiently implemented. However, with application of a combined reservation domains for various service classes, network performance could be further improved.

  15. Dynamic Subchannel Assignment-Based Cross-Layer MAC and Network Protocol for Multihop Ad Hoc Networks

    Directory of Open Access Journals (Sweden)

    Khanh Nguyen Quang

    2013-01-01

    Full Text Available The paper presents a dynamic subchannel assignment algorithm based on orthogonal frequency division multiple access technology operating in the time division duplexing and a new cross-layer design based on a proposed routing protocol jointed with the MAC protocol. The proposed dynamic sub-channel assignment algorithm provides a new interference avoidance mechanism which solves several drawbacks of existing radio resource allocation techniques in wireless networks using OFDMA/TDD, such as the hidden node and exposed node problems, mobility, and cochannels interference in frequency (CCI. Besides, in wireless networks, when a route is established, the radio resource allocation problems may decrease the end to end performance proportionally with the length of each route. The contention at MAC layer may cause the routing protocol at network layer to respond by finding new routes and routing table updates. The proposed routing protocol is jointed with the MAC protocol based on dynamic sub-channel assignment to ensure that the quality of service in multihop ad hoc networks is significantly improved.

  16. Latency-Optimized and Energy-Efficient MAC Protocol for Underwater Acoustic Sensor Networks: A Cross-Layer Approach

    Directory of Open Access Journals (Sweden)

    Qingchun Ren

    2010-01-01

    Full Text Available Considering the energy constraint for fixed sensor nodes and the unacceptable long propagation delay, especially for latency sensitive applications of underwater acoustic sensor networks, we propose a MAC protocol that is latency-optimized and energy-efficient scheme and combines the physical layer and the MAC layer to shorten transmission delay. On physical layer, we apply convolution coding and interleaver for transmitted information. Moreover, dynamic code rate is exploited at the receiver side to accelerate data reception rate. On MAC layer, unfixed frame length scheme is applied to reduce transmission delay, and to ensure the data successful transmission rate at the same time. Furthermore, we propose a network topology: an underwater acoustic sensor network with mobile agent. Through fully utilizing the supper capabilities on computation and mobility of autonomous underwater vehicles, the energy consumption for fixed sensor nodes can be extremely reduced, so that the lifetime of networks is extended.

  17. Reliable beacon transmission based MAC protocol for LR-WPANs over WLAN interferences

    Institute of Scientific and Technical Information of China (English)

    Ji-Hoon PARK; Byung-Seo KIM

    2014-01-01

    The use of IEEE 802.15.4 standard based application systems has been rapidly increasing, for example, in medical services, sensor networks, public safety systems, and home automation systems. However, issues arise from the fact that IEEE 802.15.4 standard based low rate wireless personal area networks (LR-WPANs) use the same frequency bands as wireless local area networks (WLANs), and they interfere with each other. Based on past research on this issue, the interference has a more serious impact on LR-WPANs’ performance than on WLANs’ performance. In this paper we propose a method to improve LR-WPANs’ performance while coexisting with WLANs, which is called the reliable beacon transmission based medium access control (MAC) protocol. Since the reliability of a beacon frame is important, in this method, only the beacon frame is transmitted in interference-free channels, and the data packets are transmitted in interfered channels instead of abandoning the channels altogether. This method increases the reliability of beacon frames as well as overall channel utilizations. The effectiveness of the proposed method was evaluated through extensive simulations, and this paper proves that this method improves the performance of IEEE 802.15.4 based wireless sensor networks (WSNs) over WLANs’ interferences.

  18. QoS Support Polling Scheme for Multimedia Traffic in Wireless LAN MAC Protocol

    Institute of Scientific and Technical Information of China (English)

    YANG Zhijun; ZHAO Dongfeng

    2008-01-01

    Quality of service (QoS) support is a key attribute for multimedia traffic including video, voice, and data in wireless local area networks (LANs) but is limited in 802.11-based wireless LANs. A polling-based scheme called the point coordination function (PCF) was developed for 802.11 LANs to support the trans-mission of multimedia traffic. However, the PCF is not able to meet the desired practical traffic differentiation requirements for real-time data. This paper describes a QoS support polling scheme based on the IEEE 802.11 medium access control (MAC) protocol. The scheme uses a two-level polling mechanism with the QoS classes differentiated by two different access policies. Stations with higher priority traffic such as key or real-time data form the first level and can access the common channel through an exhaustive access policy. Other stations with lower priority traffic form the second level and can access the channel through a gated access policy. A system model based on imbedded Markov chain theory and a generation function were setup to explicitly analyze the mean information packet waiting time of the two-level polling scheme. Theo-retical and simulation results show that the new scheme efficiently differentiates services to guarantee better QoS and system stability.

  19. [Study protocol of a prevention of recurrent suicidal behaviour program based on case management (PSyMAC)].

    Science.gov (United States)

    Sáiz, Pilar A; Rodríguez-Revuelta, Julia; González-Blanco, Leticia; Burón, Patricia; Al-Halabí, Susana; Garrido, Marlen; García-Alvarez, Leticia; García-Portilla, Paz; Bobes, Julio

    2014-01-01

    Prevention of suicidal behaviour is a public health priority in the European Union. A previous suicide attempt is the best risk predictor for future attempts, as well as completed suicides. The primary aim of this article is to describe a controlled study protocol designed for prevention of recurrent suicidal behaviour that proposes case management, and includes a psychoeducation program, as compared with the standard intervention (PSyMAC). Patients admitted from January 2011 to June 2013 to the emergency room of the Hospital Universitario Central de Asturias were evaluated using a protocol including sociodemographic, psychiatric, and psychosocial assessment. Patients were randomly assigned to either a group receiving continuous case management including participation in a psychoeducation program (experimental group), or a control group receiving standard care. The primary objective is to examine whether or not the period of time until recurrent suicidal behaviour in the experimental group is significantly different from that of the control group. PSyMAC proposes low cost and easily adaptable interventions to the usual clinical setting that can help to compensate the shortcoming of specific action protocols and suicidal behaviour prevention programs in our country. The evaluation of PSyMAC results will determine their real effectivity as a case-magament program to reduce suicidal risk. Copyright © 2013 SEP y SEPB. Published by Elsevier España. All rights reserved.

  20. OCR-MAC:一种新的基于CSMA的无线传感器网络MAC协议%OCR-MAC:A new CSMA-based MAC protocol for WSN

    Institute of Scientific and Technical Information of China (English)

    李朋举

    2014-01-01

    传感器网络被认为是21世纪最重要的技术之一,它将对人类未来的生活产生深远影响,其中MAC协议是WSN通信协议中最为突出也是最为重要的关键协议之一。无线传感器网络具有节点的电源能量和硬件资源受限的特点,因此设计高能效的MAC协议是MAC协议研究中具有挑战性的研究课题。基于以上目的,本文采用了CSMA机制和分簇路由协议的优点,改进了传统的MAC协议提出了OCR-MAC协议,并利用MATLAB进行了仿真,仿真结果表明,改进后的OCR-MAC协议在节能和网络数据传输方面性能更加优越。%Sensor network is considered to be one of the most important technology in the 21st century, it will have a profound impact human life in the future, and the MAC protocols are the most prominent and important key agreements in the WSN communication protocols. WSN has the characteristics of limited nodes power and hardware resources, therefore designing an energy-efficient MAC protocol is a challenging research topic in the MAC protocols’ study. Based on the above purpose, this paper adopts the advantages of CSMA mechanism and clustering routing protocols, improves the traditional MAC protocol and proposes the OCR-MAC protocol, simulations by MATLAB show that the improved OCR-MAC protocols is more superior in terms of energy saving and network data transmission.

  1. Research and Analysis of MAC Protocol in Wireless Mesh Networks%无线Mesh网络MAC协议的研究与分析

    Institute of Scientific and Technical Information of China (English)

    夏汉铸; 王志刚

    2014-01-01

    针对无线Mesh网络的网络特性,提出了无线Mesh网络MAC协议设计的一般原则,分析了MAC面临的问题,对无线Mesh网络中典型的MAC协议DCF、EDCA和DCA的实现过程进行了分析和比较,同时对MAC协议的研究方向进行了探讨。%Aiming at the network characteristics of wireless Mesh networks, the general principles of the MAC protocol design of wireless Mesh networks are proposed, the issues faced by the MAC are analyzed. And the implementation process of DCF, EDCA and DCA of typical MAC protocol in wireless Mesh networks are analyzed and compared. In the same time the research directions of MAC protocol is explored.

  2. p-RWBO: a novel low-collision and QoS-supported MAC for wireless ad hoc networks

    Institute of Scientific and Technical Information of China (English)

    LONG Keping; LI Yun; ZHAO WeiLiang; WANG ChongGang; Kazem SOHRABY

    2008-01-01

    QoS supported MAC mechanism is a key issue for supporting QoS in wireless ad hoc networks. A new backoff algorithm, named RWBO+BEB, was proposed previously to decrease the packet collision probability significantly. In this paper, it is explored how to make RWBO+BEB support service differentiation in wireless ad hoc networks, and a novel proportional service differentiation algorithm, named p-RWBO, is proposed to allocate the wireless bandwidth according to the bandwidth ratio of each station. In p-RWBO, station n's walking probability (Pw, n) is selected according to its allocated bandwidth ratio. An analytical model is proposed to analyze how to choose Pw, n according to the bandwidth ratios of station n. The simulation results indicate that p-RWBO can differentiate services in terms of both bandwidth and delay.

  3. On the MAC/network/energy performance evaluation of Wireless Sensor Networks: Contrasting MPH, AODV, DSR and ZTR routing protocols.

    Science.gov (United States)

    Del-Valle-Soto, Carolina; Mex-Perera, Carlos; Orozco-Lugo, Aldo; Lara, Mauricio; Galván-Tejada, Giselle M; Olmedo, Oscar

    2014-12-02

    Wireless Sensor Networks deliver valuable information for long periods, then it is desirable to have optimum performance, reduced delays, low overhead, and reliable delivery of information. In this work, proposed metrics that influence energy consumption are used for a performance comparison among our proposed routing protocol, called Multi-Parent Hierarchical (MPH), the well-known protocols for sensor networks, Ad hoc On-Demand Distance Vector (AODV), Dynamic Source Routing (DSR), and Zigbee Tree Routing (ZTR), all of them working with the IEEE 802.15.4 MAC layer. Results show how some communication metrics affect performance, throughput, reliability and energy consumption. It can be concluded that MPH is an efficient protocol since it reaches the best performance against the other three protocols under evaluation, such as 19.3% reduction of packet retransmissions, 26.9% decrease of overhead, and 41.2% improvement on the capacity of the protocol for recovering the topology from failures with respect to AODV protocol. We implemented and tested MPH in a real network of 99 nodes during ten days and analyzed parameters as number of hops, connectivity and delay, in order to validate our Sensors 2014, 14 22812 simulator and obtain reliable results. Moreover, an energy model of CC2530 chip is proposed and used for simulations of the four aforementioned protocols, showing that MPH has 15.9% reduction of energy consumption with respect to AODV, 13.7% versus DSR, and 5% against ZTR.

  4. On the MAC/Network/Energy Performance Evaluation of Wireless Sensor Networks: Contrasting MPH, AODV, DSR and ZTR Routing Protocols

    Directory of Open Access Journals (Sweden)

    Carolina Del-Valle-Soto

    2014-12-01

    Full Text Available Wireless Sensor Networks deliver valuable information for long periods, then it is desirable to have optimum performance, reduced delays, low overhead, and reliable delivery of information. In this work, proposed metrics that influence energy consumption are used for a performance comparison among our proposed routing protocol, called Multi-Parent Hierarchical (MPH, the well-known protocols for sensor networks, Ad hoc On-Demand Distance Vector (AODV, Dynamic Source Routing (DSR, and Zigbee Tree Routing (ZTR, all of them working with the IEEE 802.15.4 MAC layer. Results show how some communication metrics affect performance, throughput, reliability and energy consumption. It can be concluded that MPH is an efficient protocol since it reaches the best performance against the other three protocols under evaluation, such as 19.3% reduction of packet retransmissions, 26.9% decrease of overhead, and 41.2% improvement on the capacity of the protocol for recovering the topology from failures with respect to AODV protocol. We implemented and tested MPH in a real network of 99 nodes during ten days and analyzed parameters as number of hops, connectivity and delay, in order to validate our Sensors 2014, 14 22812 simulator and obtain reliable results. Moreover, an energy model of CC2530 chip is proposed and used for simulations of the four aforementioned protocols, showing that MPH has 15.9% reduction of energy consumption with respect to AODV, 13.7% versus DSR, and 5% against ZTR.

  5. Application of MAC protocol in aeronautical Ad Hoc networks%MAC协议在航空自组网中应用综述

    Institute of Scientific and Technical Information of China (English)

    曹振林; 孙荣平; 柏长帅

    2013-01-01

      MAC protocol of aeronautical Ad hoc network is a direct controller of grouping messages in the wireless channel sending and reception. Therefore,in aeronautical Ad Hoc network,it is crucial for the performance of aeronautical Ad Hoc net⁃work whether MAC protocol can efficiently and fairly use the limited wireless channel resources. The MAC functions and the in⁃fluence factors of aeronautical Ad Hoc networks on MAC protocols are summarized in in this paper. MAC protocol characteristics of the wireless Ad Hoc networks and the key technologys of aeronautical Ad Hoc networks are analyzed in combination with the application of MAC in MANET.%  航空自组网MAC协议是分组报文在无线信道上发送和接收的直接控制者,因此,在航空自组网中,MAC协议能否高效、公平地利用有限的无线信道资源对航空自组网的性能起至关重要的作用。概述了MAC的功能作用、航空自组网对MAC协议的影响因素,并结合MAC在MANET中的应用,分析了无线自组网MAC协议的特点和航空自组网MAC协议的关键技术。

  6. Research on Energy-efficient Wireless Sensor Network MAC Protocols%基于GAF的无线传感器网络MAC协议

    Institute of Scientific and Technical Information of China (English)

    付向全; 孙志毅

    2012-01-01

    节能是无线传感器网络介质访问控制(MAC)协议的首要目标,综合近年来MAC协议的研究成果,针对S-MAC、T-MAC等几种典型协议进行分析,研究出将拓扑结构控制机制引入MAC协议,可进一步降低能耗。给出了一种基于GAF拓扑控制思想的MAC协议、GS-MAC协议。GS-MAC协议可以降低处于空闲侦听状态的节点数量,是一种高效节能的协议。仿真表明,引入拓扑控制后可以达到进一步节约能耗的目的。%Energy-saving design is the primary design objective of wireless sensor networks media access control protocols.The research results of MAC protocol are summarized,and some typical MAC protocols are analyzed such as S-MAC,T-MAC and etc.Studies show that introducing Topology control mechanisms to MAC protocols can reduce energy consumption further,and a new MAC protocol (GS-MAC) is introduced for wireless sensor networks,which can provides an effective mechanism for improving energy efficiencies by reducing the number of idle listening nodes.The simulation results show that energy can be saved further by this protocol.

  7. A Self-Learning MAC Protocol for Energy Harvesting and Spectrum Access in Cognitive Radio Sensor Networks

    Directory of Open Access Journals (Sweden)

    Mohammed Hawa

    2016-01-01

    Full Text Available The fusion of Wireless Sensor Networks (WSNs and Cognitive Radio Networks (CRNs into Cognitive Radio Sensor Networks (CRSNs is quite an attractive proposal, because it allows a distributed set of low-powered sensor nodes to opportunistically access spectrum bands that are underutilized by their licensed owners (called primary users (PUs. In addition, when the PUs are actively transmitting in their own bands, sensor nodes can switch to energy harvesting mode to obtain their energy needs (for free, to achieve almost perpetual life. In this work, we present a novel and fully distributed MAC protocol, called S-LEARN, that allows sensor nodes in a CRSN to entwine their RF energy harvesting and data transmission activities, while intelligently addressing the issue of disproportionate difference between the high power necessary for the node to transmit data packets and the small amount of power it can harvest wirelessly from the environment. The presented MAC protocol can improve both the network throughput and total harvested energy, while being robust to changes in the network configuration. Moreover, S-LEARN can keep the cost of the system low, and it avoids the pitfalls from which centralized systems suffer.

  8. A MAC protocol of underwater acoustic sensor networks based on carrier sense multiple access%水声通信网基于载波侦听多路访问的MAC协议

    Institute of Scientific and Technical Information of China (English)

    智纳纳; 刘广钟; 徐明

    2015-01-01

    水下环境的限制,使得水声传感网络具有一些特别的特点。针对已存在的水声通信网络的 MAC 协议的不足,如信道利用率低、时间槽等待空闲时间、时间同步的头部等问题,提出了一种新型的基于载波侦听多路访问/无碰撞的 MAC 协议———CSMA/CF ( Carrier Sense Multiple Access/Collision Free )。该协议通过对网络中的所有节点进行排序,从而使网络中的节点在发送数据帧时具有相同的方向,从而避免冲突。也就是说,按顺序的上一个节点发送完数据之后,该节点立即发送数据,而不必等待一个最大的传输延迟。仿真结果显示,该协议在水声环境中具有较好的网络性能。%Due to limitation of the underwater environment, the underwater acoustic sensor networks(UWASN) has some unique features. Regarding the deficiency of the existing MAC protocol for UWASN, low utilization of channel, the time slot idle time waiting, head of time synchronization and other issues, a MAC protocol of UWASN based on Carrier Sense Multiple Access/Collision Free is raised in this paper. By sorting all station in the network, the station transmits data with the same direction to avoid collision. In other words, after sending data by a sequence of nodes, the nodes send data immediately, instead of waiting for the longest transmission delay. The simulation results show that the protocol in UWASN has better network performance.

  9. Performance evaluation aodv, dymo, olsr and zrpad hoc routing protocol for ieee 802.11 mac and 802.11 dcf in vanet using qualnet

    CERN Document Server

    Sharma, Manish

    2012-01-01

    In VANET high speed is the real characteristics which leads to frequent breakdown, interference etc. Therefore Performance of adhoc routing protocols is helpful to improve the Quality of Service (QOS). In this paper we studied various adhoc routing protocols, Reactive, Proactive & Hybrid, taking in to consideration parameters like speed, altitude, mobility etc in real VANET scenario. The AODV and DYMO (Reactive), OLSR (Proactive) and ZRP (hybrid) protocols are compared for IEEE 802.11(MAC) and IEEE 802.11(DCF) standard using Qualnet as a Simulation tool. Since IEEE 802.11, covers both physical and data link layer. Hence performance of the protocols in these layers helps to make a right selection of Protocol for high speed mobility. Varying parameters of VANET shows that in the real traffic scenarios proactive protocol performs more efficiently for IEEE 802.11 (MAC) and IEEE 802.11(DCF).

  10. Distributed Collision-free Protocol for AGVs in Industrial Environments

    CERN Document Server

    Marino, Dario; Pallottino, Lucia

    2011-01-01

    In this paper, we propose a decentralized coordina- tion algorithm for safe and efficient management of a group of mobile robots following predefined paths in a dynamic industrial environment. The proposed algorithm is based on a shared resources protocol and a replanning strategy. It is proved to guarantee ordered traffic flows avoiding collisions, deadlocks (stall situations) and livelock (agents move without reaching final destinations). Mutual access to resources has been proved for the proposed approach while condition on the maximum number of AGVs is given to ensure the absence of deadlocks during system evolutions. Finally conditions to verify a local livelocks will also be proposed. In consistency with the model of distributed robotic systems (DRS), no centralized mechanism, synchronized clock, shared memory or ground support is needed. A local inter-robot communication, based on sign-boards, is considered among a small number of spatially adjacent robotic units.

  11. 自适应低轨卫星MAC协议性能分析%Performance analysis of adaptive MAC protocol for LEO satellites.

    Institute of Scientific and Technical Information of China (English)

    管明祥; 王瑞春; 袁芳

    2011-01-01

    针对低轨卫星通信信道碰撞检测能力弱,时延较长和大业务量的特点,提出一种具有接入控制机制的自适应APRMAMAC协议.通过对信道负载和业务优先级判断来确定不同业务的接入概率函数,并且接入概率在每个时隙中通过更新来动态适应系统资源的变化.该MAC协议确保多个终端合理共享有限的无线资源同时,系统能达到高容量.通过仿真对语音业务丢包概率、数据包平均时延和数据业务吞吐量三个衡量协议性能指标与传统协议进行分析对比,证明了APRMA MAC协议显著改善系统性能.%Considering that weak channel collision detection ability,long propagation delay and heavy load in LEO satellite communications,a valid adaptive APRMA MAC protocol is proposed. Different access probability functionsfor different services are obtained and appropriate access probabilities for voice and data users are updated slot by slot based on the estimation of the voice traffic and the channel status. In the proposed MAC protocol limited wireless resource is allocated reasonably by multiple users and high capacity is achieved. Three performance parameters:Voice packet loss probability,average delay of data packets and throughput of data packets are considercd in simulation. Finally simulation results demonstrate that the performance of system is improved by the APRMA compared with the conventional PRMA,with an acceptable trade-off between QoS of voice and delay of data.

  12. Advantages of a TDMA based, energy-efficient, self-organizing MAC protocol for WSNs

    NARCIS (Netherlands)

    Hoesel, van L.F.W.; Nieberg, T.; Kip, H.J.; Havinga, P.J.M.

    2004-01-01

    The paper presents EMACs, a medium access protocol especially designed for wireless sensor networks. The medium access protocol consists of a fully distributed and self-organizing TDMA scheme, in which each active node periodically listens to the channel and broadcasts a short control message. This

  13. ISSAMAC:a High Speed MAC Protocol for B3G Systems

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Based on a discussion of the requirements for the multiple acess control protocol of beyond third-generation mobile systems, we in this paper articulate the needs of the new multiple acess control protocol with support of high-speed transmission and guaranteed quality of service, for voice, video and audio. In light of these, we present the design of a new multiple acess control protocol, called intelligent slot-subcarriered assignment multiple acess control protocol, to support multiple service categories and to yield high spectral efficiency. Our simulation results verify that intelligent slot-subcarriered assignment multiple acess control protocol can not only provide low delays for the real-time traffic by using bandwidth reservation and effectual scheduling, but also make full use of the limited bandwidth by using a dynamic sub-carrier assignment algorithm.

  14. Supporting service differentiation with enhancements of the IEEE 802.11 MAC protocol: Models and analysis

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    As one of the fastest growing wireless access technologies, wireless LANs must evolve to support adequate degrees of service differentiation. Unfortunately, current WLAN standards like IEEE 802.11 Distributed Coordination Function (DCF) lack this ability. Work is in progress to define an enhanced version capable of supporting QoS for multimedia traffic at the MAC layer. In this paper, we aim at gaining insight into three mechanisms to differentiate among traffic categories, i.e., differentiating the minimum contention window size, the Inter-Frame Spacing (IFS), and the length of the packet payload according to the priority of different traffic categories. We propose an analysis model to compute the throughput and packet transmission delays. In addition, we derive approximations to obtain simpler but more meaningful relationships among different parameters. Comparisons with discrete-event simulation results show that good accuracy of performance evaluation can be achieved by using the proposed analysis model.

  15. Constant Delivery Delay Protocol Sequences for the Collision Channel Without Feedback

    OpenAIRE

    Salaun, Lou; Shue Chen, Chung; Chen, Yi; Shing Wong, Wing

    2016-01-01

    International audience; We consider a collision channel model without feedback based on a time-slotted communication channel shared by K users. In this model, packets transmitted in the same time slot collide with each other and are unrecoverable. Each user accesses the channel according to an internal periodical pattern called protocol sequence. Due to the lack of feedback, users cannot synchronize their protocol sequences, leading to unavoidable collisions and varying throughput. Protocol s...

  16. Enhancing MAC performance of DCF protocol for IEEE 802.11 wireless LANs

    National Research Council Canada - National Science Library

    Woo-Yong Choi

    2017-01-01

    ...) protocol of IEEE 802.11 wireless LANs and compatible with various IEEE 802.11 PHY extensions. The performance of the DCF degrades exponentially as the number of nodes participating in the DCF transmission procedure increases...

  17. Design and Implementation of MAC Address Comparison Burning Comparison Protocol Document%MAC地址烧录比对协议文件的设计与实现

    Institute of Scientific and Technical Information of China (English)

    罗许练

    2012-01-01

    PC-board network card on the MAC address of burn,the burn must be guaranteed with a global unique MAC address.Before burning the MAC address to a computer motherboard,need to compare the MAC address will burn and the MAC address database of the server.Whether the comparison protocol document is excellent or inferior,will directly determine the global uniqueness of the MAC address burn to the computer motherboard.%对电脑主板集成网卡进行MAC地址烧录时,必须保证烧录的MAC地址具有全球唯一性。MAC地址烧录到电脑主板前,需对烧录的MAC地址与服务器上的MAC地址库进行比对。比对协议文件的优劣,将直接决定烧录到电脑主板中的MAC地址的全球唯一性。

  18. Multi-branch query tree protocol for solving RFID tag collision problem

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The technology of anti-collision is a key point in radio frequency identification (RFID) system. To avoid data collision, there are two approaches: ALOHA based algorithm and binary tree (BT) based algorithm. However, these cannot solve the collision problem completely, especially when the tag quantity is big and the tag ID is long. In this article, we present a multi-branch query tree (MBQT) protocol based on balanced incomplete block design (BIBD) code, and use 16-bit vectors derived from the BIBD as query prefix symbols of RFID reader. Compared with the conventional anti-collision algorithm, the theoretic analysis and simulation show that the proposed protocol improves the identification efficiency.

  19. Delay Analysis of an Enhancing IEEE 802.11 Point Coordination Function MAC Protocol

    Directory of Open Access Journals (Sweden)

    Zheng Guan

    2014-05-01

    Full Text Available The widespread use of multimedia networking applications has brought more requirements to the network, creating a need for end-to-end Quality of Service (QoS. The contention-free Point Coordination Function (PCF with Round Robin scheme, where the Access Point controls all transmissions based on a polling mechanism, is defined in IEEE 802.11 standard to provide QoS service. This network suffers from inefficiency in the delay sensitive traffic and makes. It is difficult to provide priority-differentiated service. In this paper, a useful enhance mechanism is derived from a two-level-polling model with a parallel scheme between the polling and switch over processes. We consider two different polling schemes according to station classify: key station and normal station. This mechanism allows for a delay guarantee as well as priority service. An analytical is developed for evaluating the queuing length for the station and waiting time for the packets at nodes. Based on this model, we achieve several closed-form expressions for mean cycle time, mean queue length and mean waiting time. To verify the correctness of our analytical model, we also develop a simulator for the 802.11 PCF MAC. The simulation results well match the analytical results.

  20. An Energy-saving On-demand Scheduling Cooperative MAC Protocol in Wireless Sensor Networks%WSN 中一种节能的按需调度协作式 MAC 协议研究

    Institute of Scientific and Technical Information of China (English)

    卫小伟

    2016-01-01

    The energy hole problem limits the lifetime of battery powered multi‐hop wireless sensor networks(WSNs) . To solve this problem ,An On‐demand Scheduling Cooperative MAC protocol(ODSC‐MAC) is proposed .By combining an on‐demand strategy and sensor cooperation intended to extend range ,ODSC‐MAC tackles the spatio‐temporal challenges for performing cooperative transmission(CT ) in multi‐hop WSN ,to prolong the lifetime of the network .In addition ,orthogonal and pipelined duty‐cycle scheduling are used for reducing the traffic contention ,and a reservation‐based wake‐up scheme is devised to bring cooperating nodes into temporary synchrony to support CT range extension .Compared with existing MAC protocols ,our NS‐2 simulations with REACT show that while explicitly accounting for the overhead of CT and practical fail‐ures of control packets in dense traffic ,ODSC‐MAC still gives almost 80% increase in network lifetime .%能量空洞问题影响了由电池供电的多跳无线传感器网络的寿命。为此,论文提出一种按需调度协作式 MAC协议(ODSC‐MAC),综合采用按需策略及可扩展(传输)范围的传感器协作机制,ODSC‐MAC 协议解决了多跳 WSN 网络进行协作式传输(CT )时存在的时空问题,延长了网络寿命。另外,采用正交管线占空比调度以缓解流量竞争,同时设计了一种基于预定策略的唤醒机制以使协作节点时间同步,并为 CT 传输范围扩展提供支持。与现有的 MAC 协议相比,基于 RE‐ACT 的 NS‐2仿真结果表明,该协议既明确考虑了 CT 传输的开销及流量密集时控制报文的实际故障,又使网络运行时间提升了近80%。

  1. Client-weighted medium-transparent MAC protocol for user-centric fairness in 60GHz radio-over-fiber WLANs

    OpenAIRE

    Kalfas, George; Maniotis, P.; Markou, S.; TSIOKOS, D; Pleros, N.; Alonso Zárate, Luis Gonzaga; Verikoukis, Christos

    2014-01-01

    We present a novel client-weighted medium-transparent medium access control (CW-MT-MAC) protocol with enhanced fairness service delivery properties accompanied by a low-loss remote access unit (RAU) architecture for use in indoor, Gbps-capable, 60 GHz radio-over-fiber (RoF) wireless local area networks (WLANs). Our approach relies on incorporating a client-weighted algorithm (CWA) in the optical capacity allocation mechanism employed in the MT-MAC scheme, so as to distribute the available wav...

  2. EPCM - an efficient power controlled MAC protocol for mobile ad hoc network

    Science.gov (United States)

    Seth, D. D.; Patnaik, S.; Pal, S.

    2014-10-01

    To reduce interference and to save a significant amount of energy, a control of transmission power is employed in Mobile Ad hoc Network. Many researchers have reported numerous transmission power control schemes to achieve the objective. Some of those techniques use higher transmission power for control packets (Request To Send/Clear To Send) and lesser power for Data and ACK packets. These schemes, though save some amount of energy, achieve least aggregate throughput due to poor spatial reuse and hidden terminal interference. In this paper, an efficient Power Controlled Medium Access Control (EPCM) scheme is evinced, which uses uniform interference aware and minimum transmission power for both Control and Data packet. The performance of EPCM is evaluated and compared with three reported Medium Access Control protocols which are based on transmission power control schemes and is observed that the proposed protocol achieves better throughput and minimal energy consumption while avoiding the hidden terminal problem.

  3. A Novel QoS-Supported MAC Protocol for Wireless Network with Smart Antennas

    Institute of Scientific and Technical Information of China (English)

    YANGJun; LIJiandong; ZHOUXiaodong

    2005-01-01

    A QoS (Quality-of-Service)-supportedad ptive slot allocation multiple access protocol QASAMA) is proposed for the wireless network with mart antenna at basestation. Time-dlvision duplexing TDD) is used in the QASAMA protocol. Driven by the asestation, each active Mobile terminal (MT) transmits training sequence at the beginning of each frame, so he spatial signature of the active MT can be obtained by the smart antenna. Based on the optimal Signal-to-interference-plus-noise ratio (SINR) beamforming, two slot allocation algorithms, Point-by-polnt optimizing (PPO) and Global optimizing (GO), are presented. On condition that provides QoS for voice and data traffics, the basestation dynamically schedules uplink and downlink traffic transmission so that multiple packets can be transmitted simultaneously in one traffic slot. Therefore, Spacedivision-multiple-access (SDMA) is realized. Approximate analysis of channel utilization is presented. Simulation results show that the proposed protocol can support the application of smart antennas effectively and provide high channel utilization and QoS for voice and data traffics.

  4. Adaptive Beaconing in Mobility Aware Clustering Based MAC Protocol for Safety Message Dissemination in VANET

    Directory of Open Access Journals (Sweden)

    Nishu Gupta

    2017-01-01

    Full Text Available Majority of research contributions in wireless access in vehicular environment (WAVE/IEEE 802.11p standard focus on life critical safety-related applications. These applications require regular status update of vehicle’s position referred to as beaconing. Periodic beaconing in vehicle to vehicle communication leads to severe network congestion in the communication channel. The condition worsens under high vehicular density where it impacts reliability and upper bound latency of safety messages. In this paper, WAVE compliant enhancement to the existing IEEE 802.11p protocol is presented which targets prioritized delivery of safety messages while simultaneously provisioning the dissemination of nonsafety messages. Proposed scheme relies on dynamic generation of beacons to mitigate channel congestion and inefficient bandwidth utilization by reducing transmission frequency of beacons. Through the use of clustering mechanism, different beaconing frequencies and different data transmission rates are assigned to prioritize vehicular mobility. Through extensive simulation results, the performance of the proposed approach is evaluated in terms of a wide range of quality of service (QoS parameters for two different transmission ranges. Results show that the proposed protocol provides significant enhancement and stability of the clustered topology in vehicular ad hoc network over existing standard and other protocols with similar applications.

  5. 一种航空武器数据链MAC协议设计与研究%Design and Research of Aeronautical Weapon Data Link MAC Protocol

    Institute of Scientific and Technical Information of China (English)

    段荣; 吕娜; 王翔

    2011-01-01

    MAC协议是航空武器数据链组网通信的重要技术,网络的性能依赖于所采用的多址接入协议,也是航空武器数据链研究的难点之一.固定分配、竞争和预约三大类MAC协议各有优缺点以及适应场景,需要根据应用需求设计对应的多址接入协议,以满足通信网络的战术和技术性能指标.在分析数字化战场通信网络——战术数据链组网通信应用的主要MAC协议的基础上,结合航空武器数据链的通信特点和体系结构,提出一种基于固定分配TDMA的航空武器数据链MAC协议—ODTCFMA协议,并对协议的时延性能进行了仿真和分析.分析结果表明,该协议能够同时满足编队战术协同和武器制导的低时延要求,对航空武器数据链的研究具有一定的借鉴意义.%MAC protocol is an important technology in communication network of aeronautical weapon data link, Depending on the used MAC protocol, network performance is also one of the main technical difficulties in the research of AWDL. The three kinds of MAC protocols, fixed allocation, reservation and competition, have advantages, disadvantages and adaption scene. The corresponding multiple access protocol is designed based on application requirements to meet the requirements of the tactical and technical communication network performance. The digital battlefield communications network MAC protocol is analyzed based on the combined characteristics and architecture of AWDL, and a TDM A based on fixed allocation MAC of aeronautical weapon data link;ODTCFMA protocol is proposed, then the protocol performance is simulated and analyzed. The analysis shows the MAC meets the requirements of both the for-mational tactical cooperation and the weapon guidance of low delay, which has reference significance for the research of AWDL.

  6. A Novel Adaptive MAC Protocol for Wireless Internet Access Network with Smart Antennas

    Institute of Scientific and Technical Information of China (English)

    YANGJun; LIJiandong

    2004-01-01

    Employing smart antennas in the Central access point (CAP) of wireless Internet access networks is studied. Based on the characteristics of the networks and smart antennas, a Polling-based Adaptive beamforming multiple access protocol (PB-ABFMA) is proposed. In PB-ABFMA, the CAP requests the corresponding Mobile terminal (MT) to transmit training sequence just before the data packets transmission, so the Temporal reference beamforming (TRB) can be performed by the smart antennas. The CAP schedules packet transmissions based on the polling mechanism and dynamic TDMA, and a mini-slot is used to keep connectivity when an MT is idle, therefore,the access delay is reduced. Meanwhile, a simple and effec-tive access method is proposed to guarantee rapid access of new arrival MTs to the channel. Based on the “requestreply” traffic, which is the main traffic in Internet, the theoretical analysis of channel utilization and mean turnaround delay is presented. Analysis and simulation results show that the proposed PB-ABFMA protocols effectively support the application of smart antennas and provide high channel utilization and low turn-around delay.

  7. 多个无线传感器网络中节能MAC协议设计%Design of Energy-efficient MAC Protocol in Wireless Sensor Networks

    Institute of Scientific and Technical Information of China (English)

    朱亮

    2012-01-01

    In wireless sensor network, medium access control (MAC) protocol is important to effective communication. According to the requirement of network lifetime and energy consumption, taking account of the drawbacks in latency and efficient,we propose a cross layer-based MAC protocol. It uses the interactions among MAC, Routing and Physical layers, and realizes multi-hop data transmission in a listen / sleep cycle by utilizing the interactions among MAC, reduces multi-hop delay of the data delivery and takes the redundancy under control after weighing the energy-consumption to reduce energy consumption of redundant nodes for wireless sensor networks. The analysis and simulation show that the improved energy-efficient MAC protocol can improve channel utility, reduce latency and energy consumption.%在无线传感器网络中,媒体访问控制(MAC)层协议影响着整个网络的性能。根据无线传感器网络对节点能耗和时延的要求,本文提出了一种基于跨层设计的节能MAC协议。利用物理层、MAC层和路由层之间的信息交互,在保证可靠通信的基础上,实现在一个监听/睡眠周期内数据多跳传输,缩短数据传输时延,并且有效控制网络数据传输的冗余度,降低冗余节点能量消耗。性能分析和仿真结果表明,节能MAC协议能够有效地降低网络时延并且减少节点能耗。

  8. New MAC Layer Protocol of Tactical Data Link%一种新型战术数据链MAC协议

    Institute of Scientific and Technical Information of China (English)

    彭沙沙; 张红梅; 卞东亮; 赵玉亭

    2013-01-01

    Aiming at the problem that Link-16 data link can not satisfy the requirements of sensitive information with reliable transmission when precision strike of moving target is needed,this paper proposed a MAC protocol based on multi-channel priority Statistics (MCPS).MCPS protocol uses different priorities thresholds and channel occupancy statistic value to determine whether data packets should be sent.Thereby,the method greatly reduces channel conflict,guarantees a data transmission in real-time at the samee.The simulation results show that the Link-16 data delay increases sharply with an increasing nodes,but MCPS protocol End to End Delay constants in 3~4ms.As network traffic increases,Link-16 system can't carry the heavy traffic and lead to severe packet loss.But MCPS can satisfy protocol requirements of high-traffic network and keep the success rate of send is not less than 95% at first time.%针对Link-16数据链无法满足未来战争中为实现移动目标精确打击而提出的时敏信息可靠传输要求的问题,提出一种基于多信道优先级统计(MCPS)的MAC协议.MCPS协议将不同优先级业务发送的门限阈值与反应信道忙闲情况的信道占用统计值作为判定数据包是否能够发送的条件,从而极大降低信道冲突,同时保证数据发送的实时性.仿真结果表明,随网络节点增多,Link-16数据链延时急剧增大,而MCPS协议的端到端延时恒定在3~4毫秒内;随着网络业务量增大,Link-16系统吞吐量无法承载持续增大的业务量而导致严重的丢包率,MCPS协议则能够满足高业务量网络的要求,并保障数据包一次发送的成功率不低于95%.

  9. PAD-MAC: primary user activity-aware distributed MAC for multi-channel cognitive radio networks.

    Science.gov (United States)

    Ali, Amjad; Piran, Md Jalil; Kim, Hansoo; Yun, Jihyeok; Suh, Doug Young

    2015-03-30

    Cognitive radio (CR) has emerged as a promising technology to solve problems related to spectrum scarcity and provides a ubiquitous wireless access environment. CR-enabled secondary users (SUs) exploit spectrum white spaces opportunistically and immediately vacate the acquired licensed channels as primary users (PUs) arrive. Accessing the licensed channels without the prior knowledge of PU traffic patterns causes severe throughput degradation due to excessive channel switching and PU-to-SU collisions. Therefore, it is significantly important to design a PU activity-aware medium access control (MAC) protocol for cognitive radio networks (CRNs). In this paper, we first propose a licensed channel usage pattern identification scheme, based on a two-state Markov model, and then estimate the future idle slots using previous observations of the channels. Furthermore, based on these past observations, we compute the rank of each available licensed channel that gives SU transmission success assessment during the estimated idle slot. Secondly, we propose a PU activity-aware distributed MAC (PAD-MAC) protocol for heterogeneous multi-channel CRNs that selects the best channel for each SU to enhance its throughput. PAD-MAC controls SU activities by allowing them to exploit the licensed channels only for the duration of estimated idle slots and enables predictive and fast channel switching. To evaluate the performance of the proposed PAD-MAC, we compare it with the distributed QoS-aware MAC (QC-MAC) and listen-before-talk MAC schemes. Extensive numerical results show the significant improvements of the PAD-MAC in terms of the SU throughput, SU channel switching rate and PU-to-SU collision rate.

  10. 三维网络拓扑结构的水声传感器网络MAC协议%Three Dimensional Topology Based MAC Protocol for Underwater Acoustic Sensor Networks

    Institute of Scientific and Technical Information of China (English)

    张迎迎; 刘广钟; 徐明

    2015-01-01

    Due to underwater acoustic sensor networks’ (UWASN) broad application prospects in recent years, it catches people’s attention gradually. However, due to restrictive underwater environment, acoustic sensor network has some uniqueness. For example, unlike two-dimensional terrestrial sensor networks, underwater acoustic sensor network is three-dimensional. Today, the most existing Medium Access Control (MAC) protocol are designed for the two-dimensional wireless sensor networks, instead of wireless networks based on 3D rarely. In this paper, we proposed a three-dimensional network topology based underwater acoustic sensor network MAC protocol. Nodes in the network will be placed to tree structure according to this protocol. This protocol uses the relationship between the child and its parent, to achieve dynamic three-dimensional networks through dynamic node algorithm. In addition, we analyze and effectively resolved the collision between the nodes, greatly improving the channel utilization. Through the simulation software contrast experimental results of different protocols on the same network topology, it confirms that our protocol can effectively save a lot of energy.%水声传感器网络Underwater Acoustic Sensor Network(UWASN)由于其广阔的应用前景,近年来逐渐被人们关注。然而由于水下环境的限制性,水声传感器网络具有其一些独特性。例如,与二维的陆地传感器网络不同,水声传感器网络是三维的。如今,现有的介质访问控制Medium Access Control(MAC)协议大多是针对二维无线传感网络,很少有基于三维水声传感器网络的 MAC 协议。针对水下三维网络,提出了基于三维网络拓扑结构的水声传感器网络 MAC 协议。该协议将网络中的节点生成树结构,并利用子节点与父节点之间的关系,通过动态节点算法实现三维动态的水声传感器网络。此外,详细分析了节点间的碰撞并有效

  11. An X-ray/optical study of the geometry and dynamics of MACS J0140.0-0555, a massive post-collision cluster merger

    CERN Document Server

    Ho, I-Ting; Richard, Johan

    2012-01-01

    We investigate the physical properties, geometry and dynamics of the massive cluster merger MACS J0140.0-0555 (z=0.451) using X-ray and optical diagnostics. Featuring two galaxy overdensities separated by about 250 kpc in projection on the sky, and a single peak in the X-ray surface brightness distribution located between them, MACS J0140.0-0555 shows the tell-tale X-ray/optical morphology of a binary, post-collision merger. Our spectral analysis of the X-ray emission, as measured by our Chandra ACIS-I observation of the system, finds the intra-cluster medium to be close to isothermal (~8.5 keV) with no clear signs of cool cores or shock fronts. Spectroscopic follow-up of galaxies in the field of MACS J0140.0-0555 yields a velocity dispersion of 875 (+70/-100) km/s (n_z=66) and no significant evidence of bimodality or substructure along the line of sight. In addition, the difference in radial velocity between the brightest cluster galaxies of the two sub-clusters of 144+/-25 km/s is small compared to typical ...

  12. An X-ray/optical study of the geometry and dynamics of MACS J0140.0-0555, a massive post-collision cluster merger

    Science.gov (United States)

    Ho, I.-Ting; Ebeling, Harald; Richard, Johan

    2012-11-01

    We investigate the physical properties, geometry and dynamics of the massive cluster merger MACS J0140.0-0555 (z = 0.451) using X-ray and optical diagnostics. Featuring two galaxy overdensities separated by about 250 kpc in projection on the sky, and a single peak in the X-ray surface brightness distribution located between them, MACS J0140.0-0555 shows the tell-tale X-ray/optical morphology of a binary, post-collision merger. Our spectral analysis of the X-ray emission, as measured by our Chandra ACIS-I observation of the system, finds the intra-cluster medium to be close to isothermal (˜8.5 keV) with no clear signs of cool cores or shock fronts. Spectroscopic follow-up of galaxies in the field of MACS J0140.0-0555 yields a velocity dispersion of 875-100+70 km s-1 (nz = 66) and no significant evidence of bimodality or substructure along the line of sight. In addition, the difference in radial velocity between the brightest cluster galaxies of the two sub-clusters of 144 ± 25 km s-1 is small compared to typical collision velocities of several 1000 km s-1. A strongly lensed background galaxy at z = 0.873 (which features variable X-ray emission from an active nucleus) provides the main constraint on the mass distribution of the system. We measure M(Technology, the University of California and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation.

  13. 一种服务区分的多媒体传感器网络MAC协议%A Service Differentiation MAC Protocol for Multimedia Sensor Networks

    Institute of Scientific and Technical Information of China (English)

    赵亮; 陈世平; 李钊伟

    2014-01-01

    In order to deliver multiple types of traffic with different requirements in highly resource constrained Wireless Sensor Networks(WSNs), this paper proposes QA-MAC, a QoS-aware and priority based MAC protocol for Wireless Multimedia Sensor Networks(WMSNs). QA-MAC aims to increase the utilization of the channel with effective service differentiation mechanisms, adaptive contention window and dynamic duty cycle according to different priority flows. It is able to ensure the demand of real-time traffic transmission. Simulations show significant improvements in terms of latency and data delivery. Compared with the S-MAC protocol, as the network load increases, the average packet transmission rate can be increased by more than 30%and it can be applied in many fields.%为在资源受限的无陑传感器网络中传输具有不同业务要求的多媒体信息,提出一种基于服务质量感知和优先级的无陑多媒体传感器网络 MAC 协议--QA-MAC。协议通过有雙的服务区分机制,对不同优先级的数据流采用不同的自适应竞争窗口调节方法和占空比调整方法,以保障不同优先级业务的实时传输要求。仿真实验结果表明,与 S-MAC 协议陒比,QA-MAC 协议在网络延迟性和数据包传输率方面都有明显提高,随着网络负载的增大,数据包传输率平均可以提高30%以上,能够较好地满足无陑多媒体传感器网络应用的需求。

  14. A Conflict-Free Low-Jitter Guaranteed-Rate MAC Protocol for Base-Station Communications in Wireless Mesh Networks

    Science.gov (United States)

    Szymanski, T. H.

    A scheduling algorithm and MAC protocol which provides low-jitter guaranteed-rate (GR) communications between base-stations (BS) in a Wireless Mesh Network (WMN) is proposed. The protocol can provision long-term multimedia services such as VOIP, IPTV, or Video-on-Demand. The time-axis is partitioned into scheduling frames with F time-slots each. A directional antennae scheme is used to provide each directed link with a fixed transmission rate. A protocol such as IntServ is used to provision resources along an end-to-end path of BSs for GR sessions. The Guaranteed Rates between the BSs are then specified in a doubly stochastic traffic rate matrix, which is recursively decomposed to yield a low-jitter GR frame transmission schedule. In the resulting schedule, the end-to-end delay and jitter are small and bounded, and the cell loss rate due to primary scheduling conflicts is zero. For dual-channel WMNs, the MAC protocol can achieve 100% utilization, as well as near-minimal queueing delays and near minimal delay jitter. The scheduling time complexity is O(NFlogNF), where N is the number of BSs. Extensive simulation results are presented.

  15. Study on parallel two-level polling cont rol based MAC protocol for Wireless sensor networks%并行调度两级轮询控制传感器网络 MAC 协议分析

    Institute of Scientific and Technical Information of China (English)

    官铮; 邹丹; 丁洪伟; 钱文华

    2014-01-01

    Aiming at the delay-sensitive applications with an unbalanced property of network flow , a new protocol called the parallel two-level polling control based MAC ( PTLP-MAC) is proposed in this paper .The PTLP-MAC provides priority distinction from the aspects of the polling route and service scheme assignment .By proceeding with the data transmission and request parallel , the mean waiting time of the data packet is further reduced. Further-more, by use of the embedded Markov chain and the theory of probability generating function , the mathematical functions were established and closed form expressions were given for obtaining the mean cyclic period , as well as the mean queue length and the mean waiting time characteristics .The analytical results were also verified through extensive computer simulations .%针对具有网络流量非均衡特性的时延敏感业务,提出一种并行调度两级轮询MAC控制协议。协议从服务策略和服务路径的角度实现了节点的优先级区分,并且通过服务过程和查询转换过程的并行处理,使得系统的时延特性显著提高。采用嵌入式马尔可夫链和概率母函数理论对提出的协议进行数学建模分析,精确解析了系统的平均排队队长、平均循环周期、信息分组的平均等待时延,仿真实验表明理论分析的正确性以及协议的有效性。

  16. Research on MAC Protocol in Wireless Sensor Networks for Electricity Information Collection System%面向用电信息采集系统的无线传感器网络MAC协议研究

    Institute of Scientific and Technical Information of China (English)

    王颖; 宋卓然; 边君君; 孙毅

    2013-01-01

    针对用电信息采集系统簇头采集器缓存占用率过高且易造成网络拥塞的问题,提出一种节点优先级自适应的PA-MAC (priority adaptive MAC)协议,根据缓存占用率动态调整节点优先级,增强缓存占用率高的节点的信道竞争力,增加节点的数据发送量,使得缓存占用率维持在较理想的水平;然后采用分布式算法,利用节点发送数据包的传输情况评估网络负载状态,结合缓存占用率及当前竞争窗口取值范围,调整竞争窗口的变化,降低数据包的碰撞概率.仿真结果表明,本算法有效缓解了采集器节点的缓存压力,提高了用电信息采集系统本地网络在归一化吞吐量、丢包率及有效传输数据量等方面的性能.%As the cluster head collector in the electricity information collection system has high buffer occupancy rate,a priority adaptive MAC (PA-MAC) protocol is presented to regulate node priority adaptively according to the buffer occupancy rate,which enhances the competition of channel for the nodes with high buffer occupancy rate,and increases data transmission quantity of nodes.By using of distributed algorithm,network load state is evaluated by the transferring status of data packets of node.And by combining buffer occupancy rate and value range of current competing window,the variation of competing window is regulated to reduce collision probability of data packets.Simulation results show that this algorithm relieves buffer pressure of collector nodes,and improves such performances as normalized saturation throughput,packet loss rate,and congestion recovery of local network for electricity information collection system.

  17. Research on MAC Protocol Simulation Analysis of Underwater Acoustic Communication%水声通信环境下MAC协议仿真分析研究

    Institute of Scientific and Technical Information of China (English)

    张文健; 王美茜; 刘旻; 刘广钟

    2015-01-01

    Deployed underwater sensor nodes can be promptly transferred the data to the land,to achieve accurate,real-time,continuous space and time underwater surveillance. In order to implement the stable communication between nodes deployed underwater and land, need to solve a series of problems. According to the characteristics of underwater sensor networks,describe the principle and basic idea of RC-MAC protocol with the receiver as the center,and the underwater simulation scene is built on the network simulation platform for the specialty of underwater environment. Simulate RC-MAC protocol,analyze and compare the throughput and energy consumption of RC-MAC protocol in diverse underwater scene. The results show that the throughput of the channel is better when the RC-MAC protocol has small number of nodes with relatively broad distribution,when the nodes distribution is shallow,the number of nodes is less than 4,saving better.%部署在水下的传感器节点可以将数据及时传送到陆地,来实现精确的、实时的、时间空间连续的水下监视。为了实现部署在水下的节点与陆地实现稳定通信,需要解决一系列问题。针对水下传感器网络的特性,首先阐述了以接收者为中心的RC-MAC协议的原理以及基本思想,并在网络仿真平台上针对水声环境特殊性搭建了水下仿真场景,对RC-MAC协议进行模拟仿真,分析比较在各种不同水声场景中RC-MAC协议的吞吐量、能量消耗等数据。通过仿真实验发现,RC-MAC协议在水下节点数量比较少、节点分布范围比较广时信道的吞吐量更高,节点分布较浅、数量小于4时节点节能效果较好。

  18. 无线传感器路由算法的应用研究%Study on Improved MAC Protocol in Wireless Sensor Network

    Institute of Scientific and Technical Information of China (English)

    步登辉

    2011-01-01

    研究无线传感器路由算法,由于网络流量的突变性、时变性,传统无线传感器路由算法不能适应网络流量变化规律,导致网络信道竞争严重不公平、多边界问题和能量浪费严重,无线传感器网络生存时间过短.为了更好适应网络流量变化规律和有效延长网络生存时间,提出一种改进的无线传感器路由算法.算法首先对传统无线传感器路由算法退避机制进行改进,使信道竞争更加公平,以应对网络流量时变性,然后采用自适应占空比机制适合网络流量突发性,最后一个周期内同时发送多个数据组的调度方法,防止边界节点问题发生,从而使网络节省能量开销.在NS2仿真平台上进行了仿真,结果表明,改进S-MAC路由算法提高了网络平均吞吐量,使信道竞争更加公平,减少能量消耗,延长了网络生存时间.%S-MAC is the most representative wireless sensor network protocol, the fixed duty cycle of S-MAC fails to adapt to the change of network traffic very well, and BEB backoff strategy brings unfairness. In order to prolong the network lifetim, an improved S-MAC protocol was put forward in this paper. The protocol improves the BEB backoff strategy, makes the entire network load balance and improves channel competition, then the adaptive duty cycle dynamic adjustment was used to adapt to network traffic, multiple data packet was sent in a working cycle to save energy costs.. Lastly experiments are cayyied out in the NS2 network simulatio. Platform. The simulation results show that the improved S-MAC protocol improves network throughput and saves more energy, and the wireless sensor network lifetime is prolonged.

  19. Modeling MAC layer for powerline communications networks

    Science.gov (United States)

    Hrasnica, Halid; Haidine, Abdelfatteh

    2001-02-01

    The usage of electrical power distribution networks for voice and data transmission, called Powerline Communications, becomes nowadays more and more attractive, particularly in the telecommunication access area. The most important reasons for that are the deregulation of the telecommunication market and a fact that the access networks are still property of former monopolistic companies. In this work, first we analyze a PLC network and system structure as well as a disturbance scenario in powerline networks. After that, we define a logical structure of the powerline MAC layer and propose the reservation MAC protocols for the usage in the PLC network which provides collision free data transmission. This makes possible better network utilization and realization of QoS guarantees which can make PLC networks competitive to other access technologies.

  20. THO-MAC:一种两跳优化的低延迟低功耗无线传感器网络介质访问控制协议%THO-MAC:a low-latency and energy-efficient MAC protocol with two-hop optimization in WS Ns

    Institute of Scientific and Technical Information of China (English)

    唐宏伟; 徐明; 孙彩霞

    2014-01-01

    Energy consumption and latency are two major problems that are primarily considered in the design of medium access control (MAC)protocols in wireless sensor networks (WSNs).A new low-latency,energy-efficient and receiver-initiated asynchronous MAC protocol in WSNs is proposed.By precisely predicting the receiver’s wakeup time,THO-MAC protocol can schedule the sender to listen to the channel,such that it can reduce the sender’s energy waste of idle listening.On the other hand,in order to reduce packet delivery latency,THO-MAC protocol chooses the forwarders in the sender’s two-hop forwarders set to minimize the two-hop forwarding latency.The performance of THO-MAC protocol in terms of detailed NS2 simulation is evaluated.The simulation results show that the THO-MAC protocol reduces 35 .5%and 1 8%packet delivery latency,while saving 23.5% and 15.5% sensor energy consumption,compared with RI-MAC and Any-MAC,the two state-of-the-art MAC protocols.%功耗与延迟是无线传感器网络介质访问控制协议设计首要考虑的两个问题。提出了一种新的传感器网络低延迟、低功耗、接收节点初始化异步介质访问控制协议---THO-MAC协议。通过准确预测接收节点的唤醒时间,THO-MAC 协议调度发送节点侦听信道,从而减少发送节点空闲侦听能量浪费。THO-MAC协议在发送节点两跳转发节点集中选择使报文两跳转发延迟最小的转发节点,从而降低报文传输延迟。使用NS2模拟器对THO-MAC协议进行了详细模拟。模拟结果显示,与RI-MAC和Any-MAC协议相比,THO-MAC协议可以减少35.5%和18%的报文传输延迟,同时节省23.5%和15.5%的节点功耗。

  1. Mac Bible

    CERN Document Server

    Spivey, Dwight

    2009-01-01

    This essential guide answers all your questions on using a Macintosh computer, whether you?re unpacking your very first Mac after switching from a PC or upgrading from an older Mac. You?ll walk through all pre-installed Mac applications, including using Mac OS X, browsing the Web using Safari, downloading music from the iTunes store, troubleshooting Mac-specific problems, organizing photos in iPhoto, organizing calendars in iCal, editing digital video in iMovie, and more.

  2. RSC-MAC Protocol for Smart Home Networks of Electric Appliances%智能家居电器网络的 RSC-MAC协议设计

    Institute of Scientific and Technical Information of China (English)

    张治元; 雷超阳

    2015-01-01

    家居电器网络由以太网、无线局域网或无线蜂窝等通信介质连接,通过发送控制消息对家用电器实现有效管理。在研究家居电器网络的基础上,提出了一种具有可靠传感和控制操作的混合M AC协议(RSC‐M AC ),并设计了支持RSC‐M AC协议的QoS(服务质量)方法,有效地保证家居电器网络中任何控制消息的延迟,提高了传感数据采集的灵活性。仿真结果表明,在规定的延迟时间内,RSC‐M AC成功交付所有的控制数据包,并在交付传感数据包时表现出良好的性能。%In smart home networks ,electric appliances are connected by communication media such as Ethernet ,WLAN ,or ZigBee .This paper introduces RSC‐MAC (reliable sensing and control‐MAC) for home appliance networks and designs a QoS (quality of service) supported MAC protocol ,which provides delay guarantee for arbitrary control messages in home networks and keeps the flexibility of sensing data collection .The simulation result shows that RSC‐MAC successfully delivers all control packets within the tolerant delay ,and has a good performance in delivering sensing packets .

  3. Aμ-MAC:An Adaptive MAC Protocol for Wireless Sensor Networks%Aμ-MAC:一种自适应的无线传感器网络MAC协议

    Institute of Scientific and Technical Information of China (English)

    古连华; 程良伦; ZHU Quan-Min

    2010-01-01

    结合基于竞争和调度机制的混合型方案是高效的无线传感器网络MAC协议的重要解决思路.μ-MAC是一种典型的混合型MAC协议,本文在深入研究μ-MAC的基础上,提出一种自适应的混合型协议Aμ-MAC.它针对动态流量的数据采集型应用,解决了μ-MAC中动态拓扑适应性及时钟同步问题,并提供了良好的流量自适应性.仿真结果表明,Aμ-MAC增强了协议的扩展性和适应性,具有更好的网络生存能力,而保留了与μ-MAC相近的节能效率和时延性能.

  4. MAC Protocol Accelerator Design over UWB%面向超宽带的MAC协议加速器设计

    Institute of Scientific and Technical Information of China (English)

    吴耀辉; 许志浩; 蔡宇; 梁丰

    2007-01-01

    IEEE802.15.3被认为是UWB技术的MAC协议可选方案之一,然而它并不完全适应于UWB的物理层,为此本文设计了一个新颖的MAC协议加速器.它把MAC层分成两个子层:上层MAC(UMAC)和下层MAC(LMAC).UMAC实现一些定时不敏感的MAC功能;而LMAC实现那些需要实时响应的MAC功能.性能分析表明吞吐量、延时等参数得到了明显改善.

  5. 基于多信道的快速数据收集MAC协议%Fast Data Collection MAC Protocol Based on Multi-channel

    Institute of Scientific and Technical Information of China (English)

    谭金勇; 杨中亮

    2013-01-01

    现有的单信道和多信道介质访问控制(MAC)协议不能很好地满足大规模数据收集应用场合对数据速率和时延的要求。为解决该问题,提出一种基于多信道的快速数据收集MAC协议,结合多信道和时分多址复用消除节点间的干扰,在节点进行时槽分配时充分考虑节点半双工通信方式和数据收集公平性,尽可能地在空间上实现信道的复用,提高数据传输的并行性。在时序调度过程中,引入网络时延能耗平衡因子,实现不同应用场合对时延和能耗的平衡调节,增强协议的灵活性。仿真结果表明,该协议在大规模数据收集应用中具有高吞吐量、低时延的特性。%Many single-channel and mufti-channel Medium Access Control(MAC) protocol can not satisfy the data rate and delay for large-scale data collection applications. To resolve this problem, a new multi-channel-based fast data collection MAC protocol is proposed, which takes advantage of mulch-channel and Time Division Multiple Access(TDMA) to eliminate interference between nodes, considers half-duplex communication mode and fairness of data collection during the time-slot assigning, and increases parallel transmissions by maximizing the spatial channel reuse. During the process of timing scheduling, the introduction of time delay and energy consumption balance factor enhances the flexibility of protocol, and it can be applied to different applications by adjusting the balance between time delay and energy consumption. Simulation results show that this protocol has the performance of high throughput and low time delay for large-scale data collection applications.

  6. 基于阵列天线的认知抗干扰 MAC 协议%A MAC Protocol for Cognitive Anti-jamming Communication with Antenna Array

    Institute of Scientific and Technical Information of China (English)

    孔得凯; 韩方景; 韩方剑; 刘伟

    2013-01-01

      应用认知无线电技术和阵列天线技术,提出了一个军事通信中认知抗干扰通信的 MAC 协议.把整个通信频段分为控制信道和业务信道两层信道,并由控制信道支撑业务信道.每个通信终端装备一部感知天线和一部4元天线阵.4元天线阵有两种工作方式:多天线独立方式和阵列天线方式.以多天线方式在控制信道完成交会,以阵列天线方式定向发射或定向接收控制信息和业务信息.通过对交会算法研究和改进,提出了多天线交会算法,并验证了此算法性能非常优越.%With the application of CR and antenna array techniques, a MAC protocol for cognitive Anti-jamming communication is proposed. In this protocol, the whole communication band is divided into two layers, namely the control channel layer and the traffic channel layer, and the traffic channel is supported by the control channel. Each communication terminal is equiped with a sensing antenna and a four-element antenna array. The four-element antenna array works in multi-antenna way or AAA way at different stages of the communication. For the multi-antenna rendezvous, the array quorum-based system algorithm by K. Bian and J. Park is studied, and thus multi-antenna rendezvous algorithm proposed. Analysis indicates that the proposed algorithm is of excellent performance.

  7. CDMA Based MAC Protocol for Underwater Sensor Networks%基于CDMA的水下传感器网络MAC协议设计

    Institute of Scientific and Technical Information of China (English)

    白磊; 冯振兴; 田立勤

    2015-01-01

    According to the characteristics that the sensor nodes in underwater sensor network ( UWSN) adopt acoustic communication, characterized by high error rate high delay, low bandwidth, multipath and Doppler shift, etc. , the current communication protocols designed for radio channels are unsuitable for underwater. So, a new dynamic and distribute code division multiple access ( CDMA)-based media ac-cess control ( MAC) protocol for UWSN was proposed. The protocol not only can save the limited energy of mobile nodes,but also increase the CDMA code reusability. The protocol can be adapted to the dynam-ic topology of UWSN. At the same time, the design of power control can minimize the near-far effect in-herit in CDMA. Simulation indicates that, compared with the static code assignment protocol and ALO-HA, the performance of the protocol mentioned above is satisfied on delivery ratio and end-to-end delay.%水下传感器网络( UWSN)中节点采用声波通信,水声信道的高误码率、长延迟、低带宽、多径效应、多普勒频散等技术,据此提出一种动态的、分布式的基于码分多址( CDMA)的水下传感器网络介质访问控制层( MAC)协议。该协议不但节能,还能够提高CDMA扩频码的重用率,并且能够适应网络拓扑的动态变化。同时,协议使用了功率控制机制,有效解决CDMA系统中普遍存在的“远-近”效应问题。仿真实验表明,与经典的静态编码分配协议和ALOHA相比,该协议在冲突率、交付率、端到端的延迟、能耗等方面具有更好的性能。

  8. Tournament MAC with Constant Size Congestion Window for WLAN

    CERN Document Server

    Galtier, Jerome

    2007-01-01

    In the context of radio distributed networks, we present a generalized approach for the Medium Access Control (MAC) with fixed congestion window. Our protocol is quite simple to analyze and can be used in a lot of different situations. We give mathematical evidence showing that our performance is tight, in the sense that no protocol with fixed congestion window can do better. We also place ourselves in the WiFi/WiMAX framework, and show experimental results enlightening collision reduction of 14% to 21% compared to the best known other methods. We show channel capacity improvement, and fairness considerations.

  9. D\\'eveloppement et analyse multi outils d'un protocole MAC d\\'eterministe pour un r\\'eseau de capteurs sans fil

    CERN Document Server

    Val, Thierry

    2008-01-01

    In this article, we present a multi-tool method for the development and the analysis of a new medium access method. IEEE 802.15.4 / ZigBee technology has been used as a basis for this new determinist MAC layer which enables a high level of QoS. This WPAN can be typically used for wireless sensor networks which require strong temporal constraints. To validate the proposed protocol, three complementary and adequate tools are used: Petri Nets for the formal validation of the algorithm, a dedicated simulator for the temporal aspects, and some measures on a real prototype based on a couple of ZigBee FREESCALE components for the hardware characterization of layers #1 and #2.

  10. An Adaptive Polling Periods MAC Protocol for Wireless Sensor Networks%一种自适应侦听的异步无线传感器网络MAC协议

    Institute of Scientific and Technical Information of China (English)

    陈德富; 陶正苏

    2011-01-01

    To improve network performance in dynamic traffic load conditions, an adaptive polling periods MAC protocol called AA-MAC is proposed. Based on short preamble sampling technology, after receiving messages rather nodes in AA-MAC perform some additional polling periods than switch off radios immediately. It allows several transmissions upon one rendezvous between the sender and its destination especially when network traffic is high. To give insight into protocol, energy consumption and network latency are both modeled. Simulations on a 9 hop linear topology illustrate that AA-MAC is superior to S-MAC in any traffic conditions and it performs equally to X-MAC in light traffic conditions and performs better than X-MAC in high traffic conditions. When traffic load is high, AA-MAC decrease network latency by 56% compared to X-MAC.%为了提升异步无线传感器网络MAC协议在动态网络负载下的性能,论文提出了一种流量自适应的异步协议AA-MAC.该协议基于短前导序列采样技术,当节点收稿数据后并不理解转入睡眠而自适应增加若干个最短侦听时间用以接收发送节点的可能其他数据,使得收发双方在网络负载较重时能实现一次配对多次收发数据.分析并对比了AA-MAC和X-MAC的能耗和延时模型.在一个9跳线形拓扑网络上的仿真结果表明:AA-MAC在各种负载下性能均优于S-MAC;当网络负载很轻时,AA-MAC表现和X-MAC相当;随着网络负载加重,AA-MAC和X-MAC能耗相当但延时减少了56%以上.

  11. 一种无线传感器网络动态多信道MAC协议%Dynamic multichannel MAC protocol for wireless sensor networks

    Institute of Scientific and Technical Information of China (English)

    张轩; 刘野; 刘昊; 李智群

    2014-01-01

    In order to alleviate the debasement of quality of service (QoS )caused by interference between transmissions from nodes in wireless sensor network and interference from WiFi devices out-side the network,a dynamic multichannel media access control (DM-MAC)protocol is proposed. First,three-way handshake scheme and distributed computing are used to allot initial channel for nodes in the network.Secondly,each node chooses a channel hopping sequence from a rectangular Latin array according to its initial channel.On this basis,channel positions among the sequence are adjusted using state transition diagram.When the number of used channels changes,the new Latin channel hopping sequence should be reconstructed according to channel state transition diagram.Fi-nally,the performance of DM-MAC is evaluated through NS2 simulations.The results show that compared to MuCHMAC protocol,DM-MAC can reduce internal interference between sensor nodes efficiently,as well as external interference from WiFi devices.Meanwhile,the proposed MAC pro-tocol improves average end-to-end delivery latency and delay bound,and increases the quality of service.%为了解决无线传感器网络内部节点干扰和外部WiFi网络干扰引起的服务质量下降问题,提出了一种动态多信道MAC协议DM-MAC.首先,通过3次握手机制和分布式计算方法为网络内节点分配初始信道.其次,构造拉丁跳频矩阵,节点根据初始信道号在矩阵中选取对应的跳频序列.在此基础上,利用状态转移图调整每个信道在跳频序列中的位置.当可用信道数量发生变化时,根据信道状态转移图生成新的拉丁跳频序列.最后,利用网络仿真软件NS2对DM-MAC通信性能进行分析.实验结果表明,与MuCHMAC协议相比,DM-MAC能够有效地降低突发流量传输时内部节点间的干扰,以及外部WiFi干扰源对无线传感器网络性能的影响.同时,该协议改善了平均端到端延时和

  12. A Power-Efficient Access Point Operation for Infrastructure Basic Service Set in IEEE 802.11 MAC Protocol

    Directory of Open Access Journals (Sweden)

    Hua Ye Ming

    2006-01-01

    Full Text Available Infrastructure-based wireless LAN technology has been widely used in today's personal communication environment. Power efficiency and battery management have been the center of attention in the design of handheld devices with wireless LAN capability. In this paper, a hybrid protocol named improved PCF operation is proposed, which intelligently chooses the access point- (AP- assisted DCF (distributed coordinator function and enhanced PCF (point coordinator function transmission mechanism of IEEE 802.11 protocol in an infrastructure-based wireless LAN environment. Received signal strength indicator (RSSI is used to determine the tradeoff between direct mobile-to-mobile transmission and transmission routed by AP. Based on the estimation, mobile stations can efficiently communicate directly instead of being routed through AP if they are in the vicinity of each other. Furthermore, a smart AP protocol is proposed as extension to the improved PCF operation by utilizing the historical end-to-end delay information to decide the waking up time of mobile stations. Simulation results show that using the proposed protocol, energy consumption of mobile devices can be reduced at the cost of slightly longer end-to-end packet delay compared to traditional IEEE 802.11 PCF protocol. However, in a non-time-critical environment, this option can significantly prolong the operation time of mobile devices.

  13. 基于SMAC的无线传感器网络MAC协议的分析与优化%Analysis and Optimization of MAC Protocol of SMAC-based Wireless Sensor Network

    Institute of Scientific and Technical Information of China (English)

    赵雪莹

    2011-01-01

    首先对MAC协议进行了相关介绍.然后重点介绍了一种基于竞争的无线传感器网络MAC层协议S-MAC协议.其核心是提出了一种新的无线传感器网络的MAC协议设计方案.基于动态调整占空比的思想,提出了ATC-SMAC协议.该协议在S-MAC协议的基础上改进了固定占空比的劣势,根据每个节点上的数据包的平均延迟调整占空比.通过动态地调整每个节点的占空比,使不同流量的节点拥有不同的工作时间,协议根据不同节点的流量情况自适应地对其占空比进行调整.经过仿真试验,得到ATC-MAC在网络端对端延迟、能量消耗以及吞吐量方面较S-MAC协议都有比较明显的提高.%The MAC protocol is introduced. A wireless sensor network MAC layer protocol based on competition named S-MAC protocol is analyzed. The core of this paper is the design scheme of MAC protocol of a new wireless sensor network, and the ATC-SMAC protocol based on the dynamic adjustment of duty cycle is proposed. This protocol improved the disadvantages of fixed duty cycle of S-MAC, and used the strategy of adjusting the duty cycle according to average packet delay on one node. Nodes with different traffic owned different work time according the duty cycle dynamic adjustment of each node. The protocol dynamically adjusted the duty cycle according to the traffic of each node. According to the simulation, the ATC-MAC is better than S-MAC in end to end delay, energy consumption and throughput.

  14. 认知无线电网络双天线多信道媒体接入控制协议%Dual-antenna multi-channel MAC protocol in cognitive radio networks

    Institute of Scientific and Technical Information of China (English)

    黄巍; 钱裕乐; 李云

    2011-01-01

    在认知无线电网络中,媒体接入控制(MAC)协议的主要功能包括信道感知、选择和接入控制,其中感知时间和传输时间的长度对网络的性能有着重要的影响.提出了一种双天线多信道分布式认知无线电MAC(TM-MAC)协议,不需要在传输之前对信道进行感知;节点可以在其他节点传输数据的同时对频谱资源进行检测,然后利用空闲的频谱资源通信;建立了数学模型分析在饱和网络状况下MAC协议的吞吐量.仿真分析表明TM-MAC协议能够有效提高网络的吞吐量.%In the cognitive radio networks, the main functions of MAC protocols include channel sensing, channel selection and access, and the detection time and transmission time have important influence on network performance. A dual- antenna multi-channel distributed MAC (TM-MAC) protocol was proposed, which was not necessary to detect channels before transmitting nodes data. The node could detect the spectrum resource while other nodes transmit data. Then, the node could transmit data by the idle spectrum resource. A model was built to analyze the throughput of TM-MAC under the saturation condition. The simulation results show that TM-MAC improves the throughput in cognitive ratio networks.

  15. Time-Based CSMA Protocol for Alleviating Collision Problem in RFID System

    Directory of Open Access Journals (Sweden)

    Poornima.R

    2013-04-01

    Full Text Available Radio Frequency Identification (RFID System admits rapid identification of entities by itself in the discipline of pervasive computing. RFID system comprises readers and tags. Readers arecommunicating with the tag by broadcasting RF signals. In existing RFID system channel assignment, tag identification and collision is a vital issue. Henceforth efforts are requisite to minimize these issues. This work evaluating the throughput of the RFID system by incorporating time into Carrier Sense Multiple Access (CSMA protocol. Time based CSMA (TCSMA depends on CSMA below low contention and TDMA below high contention in RFID system. The performance can be measured by Mat lab simulator. Time Based CSMA improves the tag read rate and also reduces the collision problem when compared to the conventional algorithm.

  16. A Highly-efficient Energy-saving Wireless Body Area Network MAC Protocol%一种高效节能的无线体域网MAC层协议

    Institute of Scientific and Technical Information of China (English)

    谢语天; 王珺; 闵建民; 司桂静

    2015-01-01

    With the rapid development of wireless sensor network technology,wearable and implantable biosensor technology,wearable and implantable wireless equipment can be used for remote monitoring signs information. To link the nodes and equipment which are atta-ched with person skin,implanted in person and surround people,wireless body area network arises at the historic moment. In WBAN, MAC protocol is responsible of conflict detection and processing,priority control,timeslot assignment,transmission order etc. So the de-sign of MAC protocol plays an important role in the reliability and efficiency of WBAN. In this paper,propose a high efficiency and ener-gy-saving MAC protocol (HE-MAC),which is based on IEEE 802. 15. 6. The protocol adopts dynamic priority control,dynamic time-slot allocation mechanism,dynamic proportion allocation mechanism of different access period length to achieve reliable transmission in the situation of low latency and low power consumption. By using the OMNet++ simulation platform,evaluate the network performance of AD-MAC protocol,IEEE 802. 15. 6 MAC protocol and CA-MAC protocol. The result of simulation shows that the proposed MAC protocol is superior to IEEE 802. 15. 6 MAC and CA-MAC in terms of throughput,power consumption and time delay.%随着无线传感网技术、可穿戴和可植入生物传感器技术的快速发展,可穿戴式和可植入式无线设备可用于远程监控体征信息. 为了连接附着于人身上、植入人体内部的节点和存在于人体周围的设备,无线体域网应运而生. 在无线体域网中,MaC协议负责节点的冲突检测与处理,优先级控制、时隙分配以及节点传输顺序,故MaC协议的设计在无线体域网的可靠性和能效性上发挥着核心作用. 文中提出了一种基于IEEE 802. 15. 6高效节能的MaC协议( HE-MaC). 该协议采用动态化的优先级控制、时隙分配机制、不同接入期长度的动态比例分配等措施实现低时延、低功

  17. Prototyping and Performance Analysis of a QoS MAC Layer for Industrial Wireless Network

    CERN Document Server

    Bossche, Adrien Van Den; Campo, Eric

    2008-01-01

    Today's industrial sensor networks require strong reliability and guarantees on messages delivery. These needs are even more important in real time applications like control/command, such as robotic wireless communications where strong temporal constraints are critical. For these reasons, classical random-based Medium Access Control (MAC) protocols present a non-null frame collision probability. In this paper we present an original full deterministic MAC-layer for industrial wireless network and its performance evaluation thanks to the development of a material prototype.

  18. An Ultra ̄Low Power MAC Protocol for Wireless Sensor Networks%一种超低功耗无线传感器网络MAC协议

    Institute of Scientific and Technical Information of China (English)

    张轩; 刘昊; 李智群

    2014-01-01

    Energy is a critical resource in wireless sensor networks. In order to save the power,sensor nodes need to sleep most of time. Therefore,precise synchronization between nodes and ultra-low sleeping energy consumption is essential for prolonging network lifetime. However,when considering the configuration of wake-up time,clock source selection and the nodes synchronization problem in the actual use of the environment. There are some problems diffi-cult to meet the requirements of the theory research. A new ultra-low power WSN MAC protocol( ULP-MAC) is pro-posed:Allow the sensor nodes to use serval kinds of clock to realize the optimal configuration of power consumption, using internal clock for the lowest power comsumption and switching to outside clock for the RF transceiver. At the same time,in order to slove the problem about the clock error increasing and the change of sleep cycle,this paper proposes the multi-clock wake-up mechanism and the nodes synchronization strategy. Finally this paper evaluates the introduced protocol and the SMAC protocol in a realistic IEEE802.15.4 test bed. The results show that,com-pared to SMAC mechanism,the ULP-MAC,which significantly decrease the sleep power comsumption and the syn-chronization time,greatly extend the life of the nodes.%在无线传感器网络中,能量是一个关键资源。传感器网络节点通常在大部分时间里处于休眠状态以节约能量。其中,节点间精确地同步和超低的休眠功耗能够本质上延长无线传感器网络节点的寿命。然而现实中节点在唤醒周期设置、时钟源选择和网络节点同步时很难满足理论研究时提出的要求。因此,提出了一种低功耗无线传感器网络MAC协议:允许节点使用多种时钟源实现功耗最优配置,在休眠时采用内部时钟以达到最低功耗,在工作时采用外部晶振以保证射频性能,同时为了解决多时钟源误差增大且休眠周期变化带来的问题,

  19. Practical Dual WiFi NIC and Multi-channel MAC Protocol%双网卡多信道无线MAC协议

    Institute of Scientific and Technical Information of China (English)

    赵蕴龙; 康世龙; 高振国; 杨飞

    2012-01-01

    多收发器多信道技术能够有效提高无线多跳网络的带宽和吞吐量,成为学术界的研究热点.多收发器多信道MAC协议研究主要涉及信道资源的分配与管理问题.在现有多信道MAC协议的研究基础上,提出一种基于IEEE802.11标准WiFi网卡的双收发器多信道MAC协议-DIM( Dual-Interface Management).协议采用信道冲突模型来分配信道资源,以优化网络的信道分布;同时,DIM协议在较少的硬件配置下,充分利用IEEE802.11标准提供的信道资源,提高了信道利用率.仿真实验表明,DIM协议具有较大的网络吞吐量和较小的分组传输延迟.%Multi-radio multi-channel technology can efficiently improve the multi-hop wireless networks' bandwidth and throughput, so that it has been becoming the researching hot spot. Among the so many researching key issues about the multi-radio multi-channel technology, wireless channel assignment and management are more important and difficult. This paper proposed a new dual-radio multi-channel MAC protocol using the standard 802. 11 WiFi NIC, named as DIM (Dual-Interface Management MAC protocol). DIM can optimize the channel assignment by applying the channel conflict model,and take full use of the available IEEE802. 11 wireless channels with little command on hardwire configuration. The simulation rtsults show that DIM has more network throughput and less latency of packets delivery.

  20. Topology-Transparent Hybrid MAC Protocol for Ad Hoc Networks%Ad Hoc网络中基于拓扑透明特性的混合MAC协议

    Institute of Scientific and Technical Information of China (English)

    李卫; 王杉; 魏急波

    2009-01-01

    A topology-transparent protocol, called topology-transparent hybrid MAC (TTHM) protocol is proposed for ad hoc networks. The proposed protocol is based on a protocol threading technique which is the basis of the threaded time spread multiple access (T-TSMA) protocol and a hybrid channel access strategy. According to the current network topology and traffic load, the proposed TTHM protocol can control each node to utilize its assigned slots and its non-assigned slots effectively. TTHM protocol is suitable for distributed application since it keeps the advantage of the topology transparency and eliminates the maximum nodal degree constraint. After the TTHM protocol is presented, its performance is analyzed. Simulation results show that the proposed TTHM protocol is better than the T-TSMA protocol.%针对ad hoc网络,提出了基于拓扑透明特性的混合MAC协议--TTHM协议(topology-transparent hybrid MAC protocol).TTHM协议在T-TSMA(threaded time spread multiple access protocol)协议所提出的螺纹协议机制的基础上引入了混合接入策略,能够根据当前的网络拓扑与业务负载,有效利用节点的分配与未分配时隙来进行报文传输.由于TTHM协议具有拓扑透明特性且克服了最大节点密度限制,因此便于分布式应用.仿真结果表明,TTHM 协议比T-TSMA协议表现出更好的性能优势.

  1. Cognitive MAC designs for OSA networks

    CERN Document Server

    Derakhshani, Mahsa

    2014-01-01

    This SpringerBrief presents recent advances in the cognitive MAC designs for opportunistic spectrum access (OSA) networks. It covers the basic MAC functionalities and MAC enhancements of IEEE 802.11. Later chapters discuss the existing MAC protocols for OSA and classify them based on characteristic features. The authors provide new research in adaptive carrier sensing-based MAC designs tailored for OSA, which optimize spectrum utilization and ensure a peaceful coexistence of licensed and unlicensed systems. Analytically devised via optimization and game-theoretic approaches, these adaptive M

  2. 基于MAC的无线传感器协议的改进%The Improvement of MAC-Based Wireless Sensor Protocol

    Institute of Scientific and Technical Information of China (English)

    陆晓希

    2007-01-01

    无线传感器TEEM(Traffic aware,Energy efficient MAC)协议是在MAC协议基础上以节量为目的流量自适应的协议.针对S-MAC(sensor MAC)协议的定期监听/睡眠模式中存在的耗能大的缺点,提出T-MAC(timeour MAC)协议.该协议是可以实现节点消息的自适应功能,从而降低耗能.仿真实验结果表明:该协议能效高,稳定性好.

  3. An On Demand Channel Assignment MAC Protocol for Multi-Channel Ad Hoc Networks%一种按需分配的多信道无线自组网MAC协议

    Institute of Scientific and Technical Information of China (English)

    赵袁

    2016-01-01

    多信道MAC协议在移动Ad Hoc网络中的应用可大幅提升其MAC层性能。现有的多信道方案大多采用划分控制信道和数据信道的方式来避免冲突,但在网络高负载时会碰到控制信道饱和的瓶颈问题,从而不能充分发挥多信道的优势。由此,提出一种按需分配的MAC协议:OM-MAC。该协议不专门划分控制信道,仅使用一个信道传输ACK,有效减少信号冲突,提高信道使用率。仿真实验证明,该协议在移动自组网中具有良好的通信性能。%The use of multi-channel MAC protocol in mobile Ad Hoc networks can greatly improve the performance of MAC layer. Most of the ex-isting multi-channel schemes adopt the method of dividing control channel and data channel to avoid conflict. But when the network load is high, the bottleneck problem of control channel saturation is encountered, which cannot make full use of the advantages of multi-chan-nel. Therefore, presents an on-demand channel assignment MAC protocol:OM-MAC. This protocol is not specifically divided into control channel, which uses only one channel to transmit ACK. This effectively reduces the signal conflict and improves the channel utilization ratio. Simulation results show that the protocol has good communication performance in mobile Ad Hoc networks.

  4. On PHY and MAC Performance in Body Sensor Networks

    Directory of Open Access Journals (Sweden)

    Sana Ullah

    2009-01-01

    Full Text Available This paper presents an empirical investigation on the performance of body implant communication using radio frequency (RF technology. In body implant communication, the electrical properties of the body influence the signal propagation in several ways. We use a Perspex body model (30 cm diameter, 80 cm height and 0.5 cm thickness filled with a liquid that mimics the electrical properties of the basic body tissues. This model is used to observe the effects of body tissue on the RF communication. We observe best performance at 3cm depth inside the liquid. We further present a simulation study of several low-power MAC protocols for an on-body sensor network and discuss the derived results. Also, the traditional preamble-based TMDA protocol is extended towards a beacon-based TDMA protocol in order to avoid preamble collision and to ensure low-power communication.

  5. On PHY and MAC Performance in Body Sensor Networks

    Directory of Open Access Journals (Sweden)

    Higgins Henry

    2009-01-01

    Full Text Available Abstract This paper presents an empirical investigation on the performance of body implant communication using radio frequency (RF technology. In body implant communication, the electrical properties of the body influence the signal propagation in several ways. We use a Perspex body model (30 cm diameter, 80 cm height and 0.5 cm thickness filled with a liquid that mimics the electrical properties of the basic body tissues. This model is used to observe the effects of body tissue on the RF communication. We observe best performance at 3cm depth inside the liquid. We further present a simulation study of several low-power MAC protocols for an on-body sensor network and discuss the derived results. Also, the traditional preamble-based TMDA protocol is extended towards a beacon-based TDMA protocol in order to avoid preamble collision and to ensure low-power communication.

  6. A TDMA based media access control protocol for wireless ad hoc networks

    Science.gov (United States)

    Yang, Qi; Tang, Biyu

    2013-03-01

    This paper presents a novel Time Division Multiplex Access (TDMA) based Media Access Control (MAC) protocol of wireless Ad Hoc network. To achieve collision free transmission, time slots in a MAC frame are cataloged into three types, that is access slot, control slot and traffic slot. Nodes in the network access to the network in the access slot, and an exclusive control is allocated subsequently. Data packets are transmission by dynamic schedule the traffic slots. Throughput and transmission delay are also analyzed by simulation experiment. The proposed protocol is capable of providing collision free transmission and achieves high throughput.

  7. A NOVEL PFMAC PROTOCOL FOR WIRELESS SENSOR NETWORK BASED ON PREDICTION AND FEEDBACK METHOD

    Institute of Scientific and Technical Information of China (English)

    Liu Yaqiu; Bian Li; Jing Weipeng; Zhang Qianlong

    2011-01-01

    In view of the problem that existing Media Access Control (MAC) protocols can not provide real-time monitor on network conditions,this paper puts forward a new MAC protocol- Predict and Feedback MAC (PFMAC) which can predict the channel's congestion level reasonably.The dominant idea of the new scheme is to record the channel's busy or idle situation in the backoff stage by sending Sensor Nodes (SNs),and according to the congestion level every SN can change the contention window adaptively when send packets successfully to minimize collisions,saving energy and channel resources.The result of simulation shows that compared with other MAC protocols,the PFMAC protocol can improve network throughput and reduce energy consumption in high speed network environment.

  8. 基于预约和反馈的无线传感器网络MAC协议研究%Research on MAC protocols for wireless sensor networks based on reservation and feedback

    Institute of Scientific and Technical Information of China (English)

    李曼; 熊庆宇; 石为人; 冀文娟

    2012-01-01

    针对无线传感器网络中对通信实时性要求较高的应用环境,引入信道预约机制和反馈机制到S-MAC协议,提出了一种低时延的RF-MAC协议.该协议在有数据需要发送时先预约信道,各节点根据预约时间表进行数据传输.采用在数据传输过程中向源节点发送反馈信息的方法,实现后续数据的提前发送.通过仿真实验表明:RF-MAC协议有效地降低了数据传输的时延,同时改善了丢包率和网络吞吐量.%Aiming at the high requirement of real-time communication application environment of wireless sensor networks,a low-latency reservation-feedback MAC( RF-MAC) protocol,which is based on channel reservation and feedback is proposed. In this MAC protocol, when a node is needed to send a data,a channel reservation message is firstly transmitted. Each node dispatches its data according to the reserved time list. The following data' s transmission is realized by using the method of sending feedback information to the source node during this process. Simulation results show that RF-MAC protocol has a good effect in reducing the data' s transmission latency of wireless sensor networks,and it also improves the packets' loss ratio and the throughput of the network.

  9. FPGA IMPLEMENTATION OF MAC HEADER BLOCK OF TRANSMITTER FOR Wi-Fi

    Directory of Open Access Journals (Sweden)

    A.M.BHAVIKATTI,

    2011-04-01

    Full Text Available For the wireless communication, IEEE 802.11 is one of the protocols available. The IEEE 802.11b uses the medium access control layer (MAC for wireless local area network. These wireless local area networks use Carrier Sense multiple access with collision avoidance (CSMA/CS for the MAC layer .But only the MAC layer for transmitter is considered here for simulation. So, the Wi-Fi transmitter module is divided into 5 blocks i.e. Data Unit Interface block, Controller block, Pay Load Data Storage, MAC Header Register block and Data Processing block. In this paper we consider only the simulation of MAC header register blocks. So, other blocks i.e. Data unit interface block, Controller block, pay load Data Storage block & Data Processing block are not discussed further in this paper. A field programmable gate array (FPGA device has been used as the hardware implementation platform. The proposed MAC-layer hardware is implemented with Xilinx xcv300e Virtex E FPGA.

  10. FPGA IMPLEMENTATION OF MAC HEADER BLOCK OF TRANSMITTER FOR Wi-Fi

    Directory of Open Access Journals (Sweden)

    A.M.BHAVIKATTI,

    2011-04-01

    Full Text Available For the wireless communication, IEEE 802.11 is one of the protocols available. The IEEE 802.11b uses the medium access control layer (MAC for wireless local area network. These wireless local area networks use Carrier Sense multiple access with collision avoidance (CSMA/CS for the MAC layer .But only the MAC layer for transmitter is considered here for simulation. So, the Wi-Fi transmitter module is divided into 5 blocks i.e. Data Unit Interface block, Controller block, Pay Load Data Storage, MAC Header Register block and Data Processing block. In this paper we consider only the simulation of MAC header register blocks. So, other blocks i.e. Data unit interface block, Controller block, pay load Data Storage block & Data Processing block are not discussed further in this paper. A field programmable gate array (FPGA device has been used as the hardware implementation platform. The proposed MAC-layer hardware is implemented with Xilinx xcv300e Virtex E FPGA

  11. Efficient MAC protocol design based on pseudo-random in WSN%无线传感网中一种基于伪随机的高效MAC协议设计

    Institute of Scientific and Technical Information of China (English)

    戴红红; 付达杰

    2014-01-01

    空闲侦听是影响多跳无线传感器网络部署能效和寿命的关键因素。虽然当前的睡眠/唤醒调度协议能避免简单流量模式时的空闲侦听,但无法有效消除随机路由协议的复杂流量模式所导致的空闲侦听问题。提出一种基于伪随机的MAC协议(MAC-PR),减少了在节点上部署大量睡眠/唤醒调度信息所产生的额外开销。MAC-PR利用伪随机发生器的种子对调度信息进行编码,然后将该种子添加到传输中的数据报文,允许各个接收器/窃听器根据种子计算出它的睡眠/唤醒调度信息。MAC-PR通过额外计算有效避免了昂贵的控制报文传输成本。通过模拟及在TelosB节点上的实际部署,验证了MAC-PR可以有效消除空闲侦听问题,使得基于随机路由协议的数据报文传输具有自稳定、低延时、低成本等特征。%Idle-listening is the key factor for energy-efficiency and longevity of multi-hop wireless sensor network(WSN)de-ployments.While existing coordinated sleep/wakeup scheduling protocols eliminate idle-listening for simple traffic patterns, they are unsuitable to handle idle-listening by producing the complex traffic patterns of the random routing protocols.This pa-per presented a MAC protocol based on pseudo-random (MAC-PR),which avoided the overhead of distributing complex,large sleep/wakeup scheduling information to the nodes.MAC-PR piggybacks onto the relayed data packets the seed of the pseudo-random generator that encoded the scheduling information,and enabled any recipient/snooper to calculate its sleep/wakeup schedule from this seed.In addition,MAC-PR trades off doing extra computation in order to avoid expensive control packet transmission cost.It shows through simulations and real implementation on TelosB motes that MAC-PR eliminates the idle-lis-tening problem,and makes the transmissions of data packets based on random routing protocal having those characteristics of self

  12. Energy-Efficient Boarder Node Medium Access Control Protocol for Wireless Sensor Networks

    Directory of Open Access Journals (Sweden)

    Abdul Razaque

    2014-03-01

    Full Text Available This paper introduces the design, implementation, and performance analysis of the scalable and mobility-aware hybrid protocol named boarder node medium access control (BN-MAC for wireless sensor networks (WSNs, which leverages the characteristics of scheduled and contention-based MAC protocols. Like contention-based MAC protocols, BN-MAC achieves high channel utilization, network adaptability under heavy traffic and mobility, and low latency and overhead. Like schedule-based MAC protocols, BN-MAC reduces idle listening time, emissions, and collision handling at low cost at one-hop neighbor nodes and achieves high channel utilization under heavy network loads. BN-MAC is particularly designed for region-wise WSNs. Each region is controlled by a boarder node (BN, which is of paramount importance. The BN coordinates with the remaining nodes within and beyond the region. Unlike other hybrid MAC protocols, BN-MAC incorporates three promising models that further reduce the energy consumption, idle listening time, overhearing, and congestion to improve the throughput and reduce the latency. One of the models used with BN-MAC is automatic active and sleep (AAS, which reduces the ideal listening time. When nodes finish their monitoring process, AAS lets them automatically go into the sleep state to avoid the idle listening state. Another model used in BN-MAC is the intelligent decision-making (IDM model, which helps the nodes sense the nature of the environment. Based on the nature of the environment, the nodes decide whether to use the active or passive mode. This decision power of the nodes further reduces energy consumption because the nodes turn off the radio of the transceiver in the passive mode. The third model is the least-distance smart neighboring search (LDSNS, which determines the shortest efficient path to the one-hop neighbor and also provides cross-layering support to handle the mobility of the nodes. The BN-MAC also incorporates a semi

  13. Energy-efficient boarder node medium access control protocol for wireless sensor networks.

    Science.gov (United States)

    Razaque, Abdul; Elleithy, Khaled M

    2014-03-12

    This paper introduces the design, implementation, and performance analysis of the scalable and mobility-aware hybrid protocol named boarder node medium access control (BN-MAC) for wireless sensor networks (WSNs), which leverages the characteristics of scheduled and contention-based MAC protocols. Like contention-based MAC protocols, BN-MAC achieves high channel utilization, network adaptability under heavy traffic and mobility, and low latency and overhead. Like schedule-based MAC protocols, BN-MAC reduces idle listening time, emissions, and collision handling at low cost at one-hop neighbor nodes and achieves high channel utilization under heavy network loads. BN-MAC is particularly designed for region-wise WSNs. Each region is controlled by a boarder node (BN), which is of paramount importance. The BN coordinates with the remaining nodes within and beyond the region. Unlike other hybrid MAC protocols, BN-MAC incorporates three promising models that further reduce the energy consumption, idle listening time, overhearing, and congestion to improve the throughput and reduce the latency. One of the models used with BN-MAC is automatic active and sleep (AAS), which reduces the ideal listening time. When nodes finish their monitoring process, AAS lets them automatically go into the sleep state to avoid the idle listening state. Another model used in BN-MAC is the intelligent decision-making (IDM) model, which helps the nodes sense the nature of the environment. Based on the nature of the environment, the nodes decide whether to use the active or passive mode. This decision power of the nodes further reduces energy consumption because the nodes turn off the radio of the transceiver in the passive mode. The third model is the least-distance smart neighboring search (LDSNS), which determines the shortest efficient path to the one-hop neighbor and also provides cross-layering support to handle the mobility of the nodes. The BN-MAC also incorporates a semi

  14. Reverse Query Tree approach to cope with Id distribution problem in Tree-based tag anti-collision protocols of RFID

    Directory of Open Access Journals (Sweden)

    Milad HajMirzaei

    2013-09-01

    Full Text Available Tag collision is one of the most important issues in RFID systems and many tag anti-collision protocols were proposed in literature. But some kind of these protocols like Tree-based protocols (specifically Query tree which its performance depends on tag id length and construction, have some issues like id distribution. In this paper we discuss about Query tree protocol which may influenced by id distribution. Then we propose a novel type of this protocol called Reverse Query tree to solve it.

  15. 一种用于水声传感网的MAC层协议%A MAC Protocol for Clustered Underwater Acoustic Sensor Networks

    Institute of Scientific and Technical Information of China (English)

    薛宸

    2015-01-01

    针对分簇的水声传感网,提出了一种基于时分多址( TDMA)的MAC层协议———Cluster-TD-MA。该协议主要由规划阶段和传输阶段组成。规划阶段,首先由网关节点规划能造成簇间干扰的子节点的传输,其次由各簇头节点分别规划本簇内其他子节点的传输;传输阶段,子节点根据规划表周期性地向簇头节点发送数据,这些数据最终汇聚到网关节点。该协议简单有效地解决了引起簇间干扰子结点的传输规划问题。 C++仿真实验表明,该协议具有良好的吞吐率和能量效率性能。%This paper proposes a MAC protocol based on time-division multiple-access( TDMA) for clus-tered underwater acoustic sensor networks ( UW-ASN) , which is named Cluster-TDMA ( C-TDMA) . C-TDMA mainly consists of scheduling stage and transmission stage. In scheduling stage, the transmissions of sensor nodes causing inter-cluster interference are scheduled first by the gateway node. Then cluster head nodes separately schedule the transmissions of other nodes in their own clusters. In transmission stage, sensor nodes periodically send data packets which finally converge to the gateway node to cluster head nodes according to schedule table. C-TDMA simply and effectively solves the problem of scheduling the transmissions of sensor nodes causing inter-cluster interference. The C++ simulation results show that C-TDMA works well in terms of throughput and energy efficiency.

  16. 无线传感器网络节能算法的优化研究%Research on Improvement Wireless Sensor Network S- MAC Protocol

    Institute of Scientific and Technical Information of China (English)

    汪华斌; 蔡昭权

    2011-01-01

    Serious energy constraints exist in wireless sensor network.Traditional.S - MAC algorithm has the problems such as node conflict, the energy waste of sensor nodes caused by fixed load setting duty ratio and short network survival time.In order to save energy and prolong the network life time, a kind of efficient and energy - saving media access control (MAC) H - algorithm is put forward.H - MAC introduces the competition mechanism convergency trees and double scheduling to settle the conflicts between nodes of S - MAC algorithm, and by the dynamic allocation placeholder instead of the fixed duty of MAC - S, the network nodes can adapt to the dynamic changes of traffic load.Simulation is carried out with NS2.The results show that compared with S - MAC, the energy efficiency of the improved H - MAC algorithm is increased by 20%, and the conflict rate of between nodes is reduced, which extends the survival time of wireless sensor network.%无线传感器网络存在严重的能量约束问题,针对传统S-MAC算法存在节点冲突、固定负载设定占空比导致感器节点的能量浪费,从而导致网络生存时间短的难题.为了节约能量、延长网络的生存时间,提出一种高效、节能的媒体接入控制算法(H-MAC).H-MAC引入数据会聚树、双调度竞争机制来改进S-MAC算法节点之间的冲突,通过将S-MAC的固定占空改为动态占位节点分配方式,使其能适应网络流量负载动态变化.最后通过NS2仿真工具对H-MAC进行了仿真.仿真结果表明,相对S-MAC来说,通过改进的H-MAC算法的节能效率提高了20%,降低了节点之间的冲突率,从而延长了整个无线传感器网络的生存时间.

  17. An Lower Energy MAC Protocol For WSNs%一种低功耗的无线传感器网络MAC协议

    Institute of Scientific and Technical Information of China (English)

    田海涛; 谭敏生; 陈伟

    2010-01-01

    本文从无线传感器网络能耗方面出发,对一些常用的基于竞争的MAC协议的优缺点进行了详细分析.通过结合WiseMAC协议和X-MAC的优点提出了XW-MAC(XWise-MAC)协议,XW-MAC协议具有更短的前导序列.通过能耗分析,XW-MAC协议的能耗比X-MAC更少.

  18. The Typical Retreats Algorithm Analysis and Simulation of AD Hoc Network MAC Protocol%无线自组网MAC层协议典型的退避算法分析与仿真

    Institute of Scientific and Technical Information of China (English)

    王亚军; 宋杰; 王传安

    2012-01-01

    MAC层协议的退避算法对Ad Hoc网络的性能有着重要的影响,研究不同退避算法的性能,对协议在实际网络中能否具体应用具有重要意义。文章介绍了Ad Hoc网络BEB退避算法和MILD退避算法的原理,分析了退避算法中几个主要参数对网络性能的影响,并利用OPNET软件对两种退避算法的性能进行了仿真,从而为实际网络环境下评估MAC层协议的性能提供参考。%MAC Protocol Retreats Algorithm has an important influence on the performance of Ad Hoc Network,studies of different Retreats Algorithm performances have important meaning for whether the protocol can apply specifically in the actual network.This paper introduces the principles of Ad Hoc Network BEB retreats algorithm and MILD retreats algorithm,analyzes the effect of several major parameters in the retreats algorithm to network performance and uses OPNET software to simulate the performances of two Retreats Algorithms,the study provides the reference for the performance assessment of MAC Protocol in the actual network environment.

  19. Analysis and simulation of energy efficiency of MAC protocol for underwater acoustic sensor networks *%水声传感器网络MAC协议的能效分析与仿真

    Institute of Scientific and Technical Information of China (English)

    罗娜; 陈名松; 王方; 薛鑫

    2011-01-01

    To study the energy loss of the MAC protocol for underwater sensor networks, the energy efficiency of the ALOHA and MACAW are analyzed and simulated based on Matlab in centralized topology. The results show that the improved MACAW protocol has much higher energy efficiency than ALOHA protocol in network which has more nodes, data arrival rate and larger packet size.%为了研究水下传感器网络多址接入(MAC)协议的能量损耗,在集中式拓扑结构下,对ALOHA和MACAW两种协议的能量效率进行了理论分析,并通过Matlab进行了仿真.结果表明:通过改进的MA.CAW协议在网络节点数较多,数据到达率较高,数据包较大的网络中比ALOHA协议具有更高的能量效率.

  20. 一种基于节点位置信息的无线传感器网络并行传输MAC协议%Concurrent Transmission MAC Protocol for Wireless Sensor Network Based on Nodes' Geographical Location Information

    Institute of Scientific and Technical Information of China (English)

    杨国燕; 张国印

    2012-01-01

    针对无线传感器网络多跳通信方式产生的暴露终端问题,提出了一种基于地理位置信息的高效并行传输LACT-MAC协议.该协议突破了传统基于CSMA协议对并行传输的限制,利用节点地理位置信息实现了暴露终端的并行传输,有效地提高了宝贵无线信道资源的复用效率.分析了根据节点的位置坐标并行传输暴露终端节点的可行性,并通过并行传输检测完成了传输过程.仿真结果证明,与标准的IEEE 802.11 DCF协议比较,LACT-MAC协议能显著提高网络的平均吞吐量,降低数据传输延迟,有效提高无线传感器网络效率和性能.%Aiming at the exposed terminal problems in multi-hop wireless sensor networks, this paper proposed the efficient concurrent transmission LACT-MAC protocol based on geographical location information. The protocol breaks through the limit of concurrent transmission based on traditional CSMA MAC protocols, for this protocol exploits nodes' geographical location information to achieve the concurrent transmission of exposed terminal, so as to enhance the reuse efficiency of the valuable wireless channel resources. According to the location coordinates of the nodes, this paper explored the feasibility analysis of concurrent transmission of exposed terminal node, and completed the concurrency check. Simulation results show that, compared to IEEE 802. 11 DCF protocol, LACT-MAC protocol can significantly improve the average throughput of the network,reduce data transmission delay,and effectively improve the efficiency and performance in wireless sensor networks.

  1. Energy-Efficient Reservation-Based Medium Access Control Protocol for Wireless Sensor Networks

    Directory of Open Access Journals (Sweden)

    Kohvakka Mikko

    2010-01-01

    Full Text Available In Wireless Sensor Networks (WSNs, a robust and energy-efficient Medium Access Control (MAC protocol is required for high energy efficiency in harsh operating conditions, where node and link failures are common. This paper presents the design of a novel MAC protocol for low-power WSNs. The developed MAC protocol minimizes the energy overhead of idle time and collisions by strict frame synchronization and slot reservation. It combines a dynamic bandwidth adjustment mechanism, multi-cluster-tree network topology, and a network channel allowing rapid and low-energy neighbor discoveries. The protocol achieves high scalability by employing frequency and time division between clusters. Performance analysis shows that the MAC protocol outperforms current state-of-the-art protocols in energy efficiency, and the energy overhead compared to an ideal MAC protocol is only 2.85% to 27.1%. The high energy efficiency is achieved in both leaf and router nodes. The models and the feasibility of the protocol were verified by simulations and with a full-scale prototype implementation.

  2. 无线传感器网络MAC协议的研究与分析%Study and Analysis of MAC Protocols in Wireless Sensor Networks

    Institute of Scientific and Technical Information of China (English)

    丁睿; 南建国

    2009-01-01

    针对不同的传感器网络应用,研究人员从不同方面提出多个无线传感器网络介质访问控制(MAC)协议,其中包括S-MAC, PMAC, DEANA, EMACs, Z-MAC以及AIMRP等协议.通过分析各类MAC典型协议特点,归纳其设计原则和分类方法,比较各协议间的性能差异,结果证明无线传感器网络MAC协议呈现多样性的特点,设计MAC协议需要兼顾能量效能和网络性能2个方面.给出MAC协议的设计策略.

  3. Macs for dummies

    CERN Document Server

    Baig, Edward C

    2014-01-01

    Get the most out of your Mac with this comprehensive guide Macs For Dummies, 13th Edition is the ultimate guide to your Mac, fully updated to include information about the latest updates. The book walks you through troubleshooting, syncing mobile devices, integrating Windows, and more, so you can take advantage of everything Macs have to offer. Whether you're a new user, a recent convert, or you just want to get the most out of your Mac, this book puts all the information you need in one place. Discover what makes Macs superior computing machines. Learn the basics, from mastering the Dock and

  4. Windows for Intel Macs

    CERN Document Server

    Ogasawara, Todd

    2008-01-01

    Even the most devoted Mac OS X user may need to use Windows XP, or may just be curious about XP and its applications. This Short Cut is a concise guide for OS X users who need to quickly get comfortable and become productive with Windows XP basics on their Macs. It covers: Security Networking ApplicationsMac users can easily install and use Windows thanks to Boot Camp and Parallels Desktop for Mac. Boot Camp lets an Intel-based Mac install and boot Windows XP on its own hard drive partition. Parallels Desktop for Mac uses virtualization technology to run Windows XP (or other operating systems

  5. Strategies for Optimal MAC Parameters Tuning in IEEE 802.15.6 Wearable Wireless Sensor Networks.

    Science.gov (United States)

    Alam, Muhammad Mahtab; Ben Hamida, Elyes

    2015-09-01

    Wireless body area networks (WBAN) has penetrated immensely in revolutionizing the classical heath-care system. Recently, number of WBAN applications has emerged which introduce potential limits to existing solutions. In particular, IEEE 802.15.6 standard has provided great flexibility, provisions and capabilities to deal emerging applications. In this paper, we investigate the application-specific throughput analysis by fine-tuning the physical (PHY) and medium access control (MAC) parameters of the IEEE 802.15.6 standard. Based on PHY characterizations in narrow band, at the MAC layer, carrier sense multiple access collision avoidance (CSMA/CA) and scheduled access protocols are extensively analyzed. It is concluded that, IEEE 802.15.6 standard can satisfy most of the WBANs applications throughput requirements by maximum achieving 680 Kbps. However, those emerging applications which require high quality audio or video transmissions, standard is not able to meet their constraints. Moreover, delay, energy efficiency and successful packet reception are considered as key performance metrics for comparing the MAC protocols. CSMA/CA protocol provides the best results to meet the delay constraints of medical and non-medical WBAN applications. Whereas, the scheduled access approach, performs very well both in energy efficiency and packet reception ratio.

  6. Enterprise Mac administrators guide

    CERN Document Server

    Smith, William

    2015-01-01

    IT departments everywhere will be integrating Macs and Mac OS X into their IT infrastructure and this book will tell them how to do it. It will serve as an authoritative, useful and frequently referenced book on Mac OS X administration.

  7. 无线车载网络MAC协议算法之性能探究%Performance research of MAC protocol algorithms in Wireless Vehicular networks

    Institute of Scientific and Technical Information of China (English)

    崔纪平; 朱东弼

    2013-01-01

    With the development of wireless communication technology,People pay more and more attentions to Wireless Access in Vehicular Environments technology.Nowadays WAVE networks has adopted some protocols,mainly including IEEE 802.11p protocol and IEEE 1609.4 protocol.In this paper,we compare the two protocols from Frame formats,Protocol Functions and intrinsical algorithm,also propose improvement to every protocol algorithm,and improve the average delay,package loss and throughput.We testify the effectiveness through software Matlab.%  随着无线通信技术的不断发展,车载环境下无线接入(Wireless Access in Vehicular Environments, WAVE)技术越来越受到人们的关注。现今车载环境下的无线网络接入技术采用了多种协议,主要协议有IEEE 802.11p WAVE协议和IEEE 1609.4 WAVE协议。本文从两协议的协议结构、功能以及固有算法等方面进行比较分析,并提出了对IEEE 802.11p协议的算法改进研究,提高了协议的平均时延、丢包率以及吞吐量的性能。并且通过Matlab仿真表明其有效性。

  8. 基于波分多址的10 Gbit/sEPON的MAC层协议研究%WDMA-based MAC protocols of 10 Gbit/s EPON

    Institute of Scientific and Technical Information of China (English)

    胡保民; 刘德明; 卢曦; 刘武

    2007-01-01

    提出了一种下行采用10 Gbit/s广播,上行采用1 Gbit/s波分多址的万兆以太无源光网络体系结构,该结构实际上下行为点对多点,上行为点对点.为解决该体系结构下的MAC(媒体接入控制)层协议控制问题,提出了一种协议模型.有别于IEEE标准802.3ah-2004的MPMC(多点MAC控制)子层,该模型提出了MWMC(多波长MAC控制)子层.给出了该结构下P2PE(点对点仿真)的实现方法,包括MWMC子层和调和层的扩展与修改以及10GBASE-R和1000BASE-X的物理层的扩展.通过点对点仿真可以使基于波分多址的万兆以太无源光网络在协议层面看起来就像上下行均采用点对点技术一样.

  9. 一种多信道混合方式的无线传感器网络MAC协议%A multichannel hybrid MAC protocol for wireless sensor networks

    Institute of Scientific and Technical Information of China (English)

    2013-01-01

    In order to improve wireless sensor networks throughput and reduce time delay, a multichannel MAC protocol called MCHMAC is designed, which use contention based and scheduled based hybrid access mechanism to transmit information, the energy is saved by dynamically adjusts the active and sleep time of nodes. MCHMAC use channel state estimation algorithm to evaluate channel, it also proposes to find a best channel by a channel schedule table for nodes. Experimental results show that this protocol improves the throughput and reduces the network delay.%  为了提高无线传感器网络的吞吐量,降低时延,本文设计了一种多信道MAC协议——MCHMAC。它采用调度和竞争访问机制相结的混合方式来传输信息,通过动态调整节点的活跃与睡眠状态的时长来节省能量。MCHMAC使用信道状态估计算法对信道进行评估,利用信道调度表来为节点调度状态最优的信道。仿真实验结果证明,本协议提高了吞吐量,降低了网络时延。

  10. Optimal Relay Selection using Efficient Beaconless Geographic Contention-Based Routing Protocol in Wireless Adhoc Networks

    Directory of Open Access Journals (Sweden)

    G. Srimathy

    2012-04-01

    Full Text Available In Wireless Ad hoc network, cooperation of nodes can be achieved by more interactions at higher protocol layers, particularly the MAC (Medium Access Control and network layers play vital role. MAC facilitates a routing protocol based on position location of nodes at network layer specially known as Beacon-less geographic routing (BLGR using Contention-based selection process. This paper proposes two levels of cross-layer framework -a MAC network cross-layer design for forwarder selection (or routing and a MAC-PHY for relay selection. CoopGeo; the proposed cross-layer protocol provides an efficient, distributed approach to select next hops and optimal relays to form a communication path. Wireless networks suffers huge number of communication at the same time leads to increase in collision and energy consumption; hence focused on new Contention access method that uses a dynamical change of channel access probability which can reduce the number of contention times and collisions. Simulation result demonstrates the best Relay selection and the comparative of direct mode with the cooperative networks. And Performance evaluation of contention probability with Collision avoidance.

  11. Mac at Work

    CERN Document Server

    Sparks, David

    2011-01-01

    Bridge the gap between using a Mac at home and at the office. Now that you love your Mac at home, you want to use one at the office without missing a beat of productivity or professionalism. This unique guide shows you how.  You'll find best Mac business practices for handling word processing, spreadsheet and presentation creation, task and project management, and graphics. The book also explores topics such as hardware maintenance, how to synchronize with multiple computers, data backup, and communication with Windows networks.: Covers the nuts and bolts of using a Mac at work, including sync

  12. 基于硬件多线程网络处理器功耗可控无线局域网MAC协议实现%Power controllable WLAN MAC protocol implementation based on hardware multi-threaded network processor

    Institute of Scientific and Technical Information of China (English)

    王磊; 张晓彤; 张艳丽; 王沁

    2012-01-01

    针对在如何在提高网络吞吐率并满足实时性需求的同时消耗更少的功耗的问题,以硬件多线程网络处理为平台,以IEEE 802.11 MAC层协议为例,通过对MAC层数据流的模式、数据流上的操作行为以及时间约束进行建模并测试分析,提出一种多线程化网络协议的软件实现方法;配合动态功耗可控的多线程网络处理器能够根据流量和实时性自适应地调整系统的性能.实验结果证明,异构多线程结构程序在实时性任务时五个软件线程需四个硬件线程支持,而无实时性任务只需两个硬件线程支持.提出的多线程MAC层协议编程模型能够达到根据网络负载特征动态控制处理器性能的目的.%How to improve network throughput and meet the real-time while consuming less power process are key concerns during network processor designing. Hardware multi-threaded network processor as a platform, IEEE 802. 11MAC layer proto-col as an example, modeling based on MAC layer data stream model, data stream operation behavior and time constraints and test the model. This paper presented a multi-threaded network protocol software implementation method. This method could adjust system performance based on traffic and real-time with dynamic power controlled multi-threaded network processor, thereby reducing power consumption when the processor was running. The result shows that real-time tasks require 4 hard threads on multi-threaded processor while only 2 are required for non-realtime tasks. This programming model provided proces-sors the ability to dynamically adapt network workload characteristics.

  13. 基于NS-3的水声传感器网络CW-MAC协议吞吐量分析%Analysis of Underwater Acoustic Sensor Network CW-MAC Protocol Throughput Based on NS-3

    Institute of Scientific and Technical Information of China (English)

    张文健; 秦汉张; 王美茜

    2014-01-01

    随着微型传感器技术、无线通信技术、微电子系统制造技术以及嵌入式技术的发展,集感知、存储计算和通信能力于一体的无线集成传感器得到越来越广泛的应用,水下传感器网络就是其中的一个重要应用领域。针对水下传感器网络的特性,详细阐述基于竞争的CW-MAC协议基本思想和新型网络仿真平台NS-3,并在NS-3上搭建仿真场景,对CW-MAC协议进行模拟仿真。改变仿真节点参数,着重比较每次仿真结果得到的信道平均吞吐量。仿真结果为搭建最佳水下通信节点条件提供重要依据。%With the development of micro-sensor technology, wireless communication technology, microelectronics systems manufacturing and em-bedded technology;with perception, storage computing and communications capabilities in one wireless integrated sensor to get more and more widely used. Underwater sensor network is one of the most important application areas. According to the characteristics of underwa-ter sensor network, elaborates based on the competition CW-MAC protocol basic idea and the new network simulation platform NS-3, and to build a simulation scenario on NS-3, on the CW-MAC protocol simulation. Changes the parameters of the simulation nodes, focuses on comparing the each simulation results obtained channel average throughput. Simulation results show the best conditions to build underwa-ter communication node provides the basis.

  14. Enterprise Mac Security Mac OS X Snow Leopard Security

    CERN Document Server

    Edge, Stephen Charles; Hunter, Beau; Sullivan, Gene; LeBlanc, Dee-Ann

    2010-01-01

    A common misconception in the Mac community is that Mac's operating system is more secure than others. While this might be true in certain cases, security on the Mac is still a crucial issue. When sharing is enabled or remote control applications are installed, Mac OS X faces a variety of security threats. Enterprise Mac Security: Mac OS X Snow Leopard is a definitive, expert-driven update of the popular, slash-dotted first edition and was written in part as a companion to the SANS Institute course for Mac OS X. It contains detailed Mac OS X security information, and walkthroughs on securing s

  15. A Fair-Priority MAC design in Networked Control System

    Directory of Open Access Journals (Sweden)

    Hongjun Li

    2009-10-01

    Full Text Available Media Access Control (MAC protocols in Wireless Networked Control System (WNCS must minimize the radio energy costs in sensor nodes. Latency and throughput are also important design features for MAC protocols in the applications. But most of them cannot guarantee quality for real-time traffic. This paper studies the state of the art of current real-time MAC protocols, and then introduces a medium access control protocol and a improved protocol that provide multiple priority levels and hard real-time transmission. The channel is accessed by sensors according to their priorities. Sensors send frames in a round manner with same priority. The fairness between different priorities is provided. The channel access procedure is divided into two stages: broadcast period and transmission period. Simulation and experiment results indicate that our protocol provides high channel utilization and bounded delays for real-time communication and can be well applied in the many fields especially the dynamic wireless sensor networks.

  16. Multichannel MAC Layer In Mobile Ad—Hoc Network

    Science.gov (United States)

    Logesh, K.; Rao, Samba Siva

    2010-11-01

    This paper we presented the design objectives and technical challenges in Multichannel MAC protocols in Mobile Ad-hoc Network. In IEEE 802.11 a/b/g standards allow use of multiple channels, only a single channel is popularly used, due to the lack of efficient protocols that enable use of Multiple Channels. Even though complex environments in ad hoc networks require a combined control of physical (PHY) and medium access control (MAC) layers resources in order to optimize performance. And also we discuss the characteristics of cross-layer frame and give a multichannel MAC approach.

  17. A Unified NET-MAC-PHY Cross-layer Framework for Performance Evaluation of Multi-hop Ad hoc WLANs

    Directory of Open Access Journals (Sweden)

    Rachid El-Azouzi

    2014-09-01

    Full Text Available Most of the existing works have been evaluated the performance of 802.11 multihop networks by considering the MAC layer or network layer separately. Knowing the nature of the multi-hop ad hoc networks, many factors in different layers are crucial for study the performance of MANET. In this paper we present a new analytic model for evaluating average end-to-end throughput in IEEE 802.11e multihop wireless networks. In particular, we investigate an intricate interaction among PHY, MAC and Network layers. For instance, we incorporate carrier sense threshold, transmission power, contention window size, retransmissions retry limit, multi rates, routing protocols and network topology together. We build a general cross-layered framework to represent multi-hop ad hoc networks with asymmetric topology and asymmetric traffic. We develop an analytical model to predict throughput of each connection as well as stability of forwarding queues at intermediate nodes in saturated networks. To the best of our knowledge, it seems that our work is the first wherein general topology and asymmetric parameters setup are considered in PHY/MAC/Network layers. Performance of such a system is also evaluated through simulation. We show that performance measures of the MAC layer are affected by the traffic intensity of flows to be forwarded. More precisely, attempt rate and collision probability are dependent on traffic flows, topology and routing.

  18. An Improved Protocol of Ad Hoc Based on Multichannel Statistics on MAC Layer%一种基于多信道统计的Ad Hoc网络MAC层协议

    Institute of Scientific and Technical Information of China (English)

    卞东亮; 张红梅; 彭沙沙; 赵玉亭

    2013-01-01

    针对现代战场对新型数据链提高实时精确打击能力,在网络高负载时传输低延时的要求,以Ad Hoc网络为基础,其相应MAC层提出了一种基于多信道优先级统计的算法(PSMC).协议采用将优先级阈值与信道统计作对比的方式,判定数据是否发送.同时采用时槽、信元等机制保障数据发送的可靠性.PSMC协议能够保证数据的成功发送延时维持在极低水平,较好地满足各优先级业务的QoS,尤其对较高优先级的业务提供了实时、安全的保障;较之经典的ALOHA、Slotted ALOHA协议,结果表明PSMC协议可以承载较大的流量负荷,保证较高的吞吐量,甚至在网络超载的情况下,通过截流的方式仍然能够保障整个网络系统继续工作,不至于快速崩溃.%For improving real-time accurate strike capability and the low delay transmission in high traffic-load of new data link in the modern battlefield, the MAC layer adopts an improved algorithm named Priority Statistic based on Multichannel Access Method(PSMC )with Ad Hoc network as a basis. In the protocol the mode of comparing the priority threshold value with the channel occupancy statistics is adopted to determine whether to transmit the data or not. Also mini-slot and cell are adopted to protect data transmission reliability. Simulation results show that PSMC protocol can ensure that successful sending of data be maintained at the level of very low delay and satisfy the QoS of every Priority, especially provide real-time, safe guarantee for the high-priority. Compared to classic protocol of ALOHA, Slotted ALOHA, the results show that PSMC can carry heavy traffic load and ensure high throughput. Even in the case of overloading, it also can go on working with throttling back traffic.

  19. Advertisement-Based Energy Efficient Medium Access Protocols for Wireless Sensor Networks

    Science.gov (United States)

    Ray, Surjya Sarathi

    One of the main challenges that prevents the large-scale deployment of Wireless Sensor Networks (WSNs) is providing the applications with the required quality of service (QoS) given the sensor nodes' limited energy supplies. WSNs are an important tool in supporting applications ranging from environmental and industrial monitoring, to battlefield surveillance and traffic control, among others. Most of these applications require sensors to function for long periods of time without human intervention and without battery replacement. Therefore, energy conservation is one of the main goals for protocols for WSNs. Energy conservation can be performed in different layers of the protocol stack. In particular, as the medium access control (MAC) layer can access and control the radio directly, large energy savings is possible through intelligent MAC protocol design. To maximize the network lifetime, MAC protocols for WSNs aim to minimize idle listening of the sensor nodes, packet collisions, and overhearing. Several approaches such as duty cycling and low power listening have been proposed at the MAC layer to achieve energy efficiency. In this thesis, I explore the possibility of further energy savings through the advertisement of data packets in the MAC layer. In the first part of my research, I propose Advertisement-MAC or ADV-MAC, a new MAC protocol for WSNs that utilizes the concept of advertising for data contention. This technique lets nodes listen dynamically to any desired transmission and sleep during transmissions not of interest. This minimizes the energy lost in idle listening and overhearing while maintaining an adaptive duty cycle to handle variable loads. Additionally, ADV-MAC enables energy efficient MAC-level multicasting. An analytical model for the packet delivery ratio and the energy consumption of the protocol is also proposed. The analytical model is verified with simulations and is used to choose an optimal value of the advertisement period

  20. ZEA-TDMA: design and system level implementation of a TDMA protocol for anonymous wireless networks

    Science.gov (United States)

    Banerjee, Debasmit; Dong, Bo; Biswas, Subir

    2013-05-01

    Wireless sensor network used in military applications may be deployed in hostile environments, where privacy and security is of primary concern. This can lead to the formation of a trust-based sub-network among mutually-trusting nodes. However, designing a TDMA MAC protocol is very challenging in situations where such multiple sub-networks coexist, since TDMA protocols require node identity information for slot assignments. This paper introduces a novel distributed TDMA MAC protocol, ZEA-TDMA (Zero Exposure Anonymous TDMA), for anonymous wireless networks. ZEA-TDMA achieves slot allocation with strict anonymity constraints, i.e. without nodes having to exchange any identity revealing information. By using just the relative time of arrival of packets and a novel technique of wireless collision-detection and resolution for fixed packetsizes, ZEA-TDMA is able to achieve MAC slot-allocation which is described as follows. Initially, a newly joined node listens to its one-hop neighborhood channel usage and creates a slot allocation table based on its own relative time, and finally, selects a slot that is collision free within its one-hop neighborhood. The selected slot can however cause hidden collisions with a two-hop neighbor of the node. These collisions are resolved by a common neighbor of the colliding nodes, which first detects the collision, and then resolve them using an interrupt packet. ZEA-TDMA provides the following features: a) it is a TDMA protocol ideally suited for highly secure or strictly anonymous environments b) it can be used in heterogeneous environments where devices use different packet structures c) it does not require network time-synchronization, and d) it is insensitive to channel errors. We have implemented ZEA-TDMA on the MICA2 hardware platform running TinyOS and evaluated the protocol functionality and performance on a MICA2 test-bed.

  1. 有向Ad hoc网络中一种基于DNAV包调度的多址接入协议%Novel directional-NAV-based packets scheduling for MAC protocol in directional antenna of Ad hoc networks

    Institute of Scientific and Technical Information of China (English)

    崔苗; 石春; 曹英烈

    2011-01-01

    For directional antennas application in mobile Ad hoc networks, proposed a novel directional network allocation vector-based packets scheduling (DAPS) algorithm.The algorithm divided the surrounding region of the node using the DNAV parameters, and eliminated the region that was not available, lastly chose the ideal destination node to send the packet.Simulations results on OPNET environment explicitly show the DAPS scheme can enable higher throughput while effectively solving the HOL blocking problem.%移动Ad hoc网络中应用方向性天线,在增加网络吞吐量的同时会产生队列头阻塞问题(head of line blocking,HOL).提出一种基于有向网络分配矢量包调度的多址接入协议(directional network allocation vector-based packets scheduling for MAC protocol,DAPS),使用有向网络分配矢量(directional network allocation vector,DNAV)作为包调度的策略,将节点周边区域进行划分,在可用区域内选择理想目的数据包进行发送.利用OP-NET仿真软件对其进行了网络仿真,并在结果分析中验证了DAPS协议更适合网络拓扑结构的变化,且有效地解决了HOL问题和进一步提高了网络吞吐量.

  2. 一种自适应功率控制的信道预约多址接入协议%Channel reservation MAC protocol with adaptive power control mechanism carrier sensing

    Institute of Scientific and Technical Information of China (English)

    袁韵洁; 李波; 闫中江

    2013-01-01

    提出了一种动态调整发送功率和载波侦听门限的信道预约多址接入协议(PC-CRM).该协议将功率控制技术应用于信道预约机制,通过对预约节点发送功率的优化设定和载波侦听门限的动态调整,使得相邻节点可以同时复用信道,从而在增强预约稳定性的基础上,提升了网络容量,降低了节点能耗.仿真结果显示,与IEEE 802.11 DCF和基本信道预约协议相比,PC-CRM协议在网络吞吐率、能量消耗效率和分组延迟抖动方面均有明显优势.%vA channel reservation MAC protocol with the adjustable transmission power and carrier sensing threshold, called PC-CRM, is proposed. PC-CRM solves the problems of poor transmission quality, low network capacity and high energy consumption, which are caused by the distributed contention based channel access scheme in Ad Hoc networks. By employing power control into the channel reservation schemes, PC-CRM adjusts the transmission power and carrier sensing threshold to the optimum values, such that the channel is multiplexed in space. Additionally, PC-CRM is also capable of stabilizing the channel reservation, improving the network capacity, and reducing the energy cost. Simulation results show that, compared with IEEE 802. 11DCF and the basic channel reservation scheme, PC-CRM performs better in terms of the throughput, energy efficiency and delay jitter.

  3. Scheduled MAC in Beacon Overlay Networks for Underwater Localization and Time-Synchronization

    NARCIS (Netherlands)

    van Kleunen, W.A.P.; Meratnia, Nirvana; Havinga, Paul J.M.

    2011-01-01

    In this article we introduce a MAC protocol designed for underwater localization and time-synchronisation. The MAC protocol assumes a network of static reference nodes and allows blind nodes to be localized by listening-only to the beacon messages. Such a system is known to be very scalable. We show

  4. Increasing the quantity and quality of searching for current best evidence to answer clinical questions: protocol and intervention design of the MacPLUS FS Factorial Randomized Controlled Trials

    National Research Council Canada - National Science Library

    Agoritsas, Thomas; Iserman, Emma; Hobson, Nicholas; Cohen, Natasha; Cohen, Adam; Roshanov, Pavel S; Perez, Miguel; Cotoi, Chris; Parrish, Rick; Pullenayegum, Eleanor; Wilczynski, Nancy L; Iorio, Alfonso; Haynes, R Brian

    2014-01-01

    .... This trial seeks to test three innovative interventions, among clinicians registered to MacPLUS FS, to increase the quantity and quality of searching for current best evidence to answer clinical questions...

  5. Multi-channel Dual Clocks three-dimensional probability Random Multiple Access protocol for Wireless Public Bus Networks based on RTS/CTS mechanism

    Directory of Open Access Journals (Sweden)

    Zhou Sheng Jie

    2016-01-01

    Full Text Available A MAC protocol for public bus networks, called Bus MAC protocol, designed to provide high quality Internet service for bus passengers. The paper proposed a multi-channel dual clocks three-demission probability random multiple access protocol based on RTS/CTS mechanism, decreasing collisions caused by multiple access from multiple passengers. Use the RTS/CTS mechanism increases the reliability and stability of the system, reducing the collision possibility of the information packets to a certain extent, improves the channel utilization; use the multi-channel mechanism, not only enables the channel load balancing, but also solves the problem of the hidden terminal and exposed terminal. Use the dual clocks mechanism, reducing the system idle time. At last, the different selection of the three-dimensional probabilities can make the system throughput adapt to the network load which could realize the maximum of the system throughput.

  6. An Energy Efficient MAC Proto col for Linear WSNs

    Institute of Scientific and Technical Information of China (English)

    DAI Guoyong; MIAO Chunyu; YING Kezhen; WANG Kai; CHEN Qingzhang

    2015-01-01

    Wireless sensor networks (WSNs) have been employed as an ideal solution in many applications for data gathering in harsh environment. Energy consumption is a key issue in wireless sensor networks since nodes are often battery operated. Medium access control (MAC) pro-tocol plays an important role in energy efficiency in wire-less sensor networks because nodes’ access to the shared medium is coordinated by the MAC layer. An energy ef-ficient MAC protocol is designed for data gathering in linear wireless sensor networks. In order to enhance the performance, when a source node transmits data to the sink, proper relay nodes are selected for forwarding data according to the energy consumption factor and residual energy balance factor. Some simulation experiments are conducted and the results show that, the proposed proto-col provides better energy efficiency and long lifetime than the existing DMAC protocol.

  7. Link-layer jamming attacks on S-MAC

    NARCIS (Netherlands)

    Law, Yee Wei; Hartel, Pieter; Hartog, den Jerry; Havinga, Paul

    2005-01-01

    We argue that among denial-of-service (DoS) attacks, link-layer jamming is a more attractive option to attackers than radio jamming is. By exploiting the semantics of the link-layer protocol (aka MAC protocol), an attacker can achieve better efficiency than blindly jamming the radio signals alone. W

  8. MDS-Mac: a scheduled MAC for localization, time-synchronisation and communication in underwater acoustic networks

    NARCIS (Netherlands)

    Kleunen, van Wouter; Meratnia, Nirvana; Havinga, Paul J.M.

    2012-01-01

    In this paper we describe a design for an underwater MAC protocol which combines localization, time-synchronisation and communication. This protocol is designed for small-scale clustered networks in which all nodes are able to ommunicate with each other. We consider an integrated design of localizat

  9. Handling Deafness Problem of Scheduled Multi-Channel Polling MACs

    Science.gov (United States)

    Jiang, Fulong; Liu, Hao; Shi, Longxing

    Combining scheduled channel polling with channel diversity is a promising way for a MAC protocol to achieve high energy efficiency and performance under both light and heavy traffic conditions. However, the deafness problem may cancel out the benefit of channel diversity. In this paper, we first investigate the deafness problem of scheduled multi-channel polling MACs with experiments. Then we propose and evaluate two schemes to handle the deafness problem. Our experiment shows that deafness is a significant reason for performance degradation in scheduled multi-channel polling MACs. A proper scheme should be chosen depending on the traffic pattern and the design objective.

  10. Recent results from MAC

    Energy Technology Data Exchange (ETDEWEB)

    MAC Collaboration

    1982-05-01

    Some preliminary results from the MAC detector at PEP are presented. These include measurements of the angular distribution of ..gamma gamma.., ..mu mu.. and tau tau final states, a determination of the tau lifetime, a measurement of R, and a presentation of the inclusive muon p/sub perpendicular/ distribution for hadronic events.

  11. MAC of xenon and halothane in rhesus monkeys.

    Science.gov (United States)

    Whitehurst, S L; Nemoto, E M; Yao, L; Yonas, H

    1994-10-01

    Local cerebral blood flow (LCBF) maps produced by 33% xenon-enhanced computed tomographic scanning (Xe/CT LCBF) are useful in the clinical diagnosis and management of patients with cerebrovascular disorders. However, observations in humans that 25-35% xenon (Xe) inhalation increases cerebral blood flow (CBF) have raised concerns that Xe/CT LCBF measurements may be inaccurate and that Xe inhalation may be hazardous in patients with decreased intracranial compliance. In contrast, 33% Xe does not increase CBF in rhesus monkeys. To determine whether this interspecies difference in the effect of Xe on CBF correlates with an interspecies difference in the anesthetic potency of Xe, we measured the minimum alveolar concentration (MAC) of Xe preventing movement to a tail-clamp stimulus in rhesus monkeys. Using a standard protocol for the determination of MAC in animals, we first measured the MAC of halothane (n = 5), and then used a combination of halothane and Xe to measure the MAC of Xe (n = 7). The halothane MAC was 0.99 +/- 0.12% (M +/- SD), and the Xe MAC was 98 +/- 15%. These results suggest that the MAC of Xe in rhesus monkeys is higher than the reported human Xe MAC value of 71%. Thus the absence of an effect of 33% Xe on CBF in the rhesus monkey may be related to its lower anesthetic potency.

  12. Macs For Seniors For Dummies

    CERN Document Server

    Chambers, Mark L

    2012-01-01

    You're never too old to fall in love—with your Mac! You took a while, but you are now the proud owner of your first Mac computer. Macs For Seniors For Dummies is just for you. This friendly, accessible guide walks you through choosing a Mac and learning how to use it. You'll find yourself falling head over heels for your Mac in no time. Macs For Seniors For Dummies introduces you to all the basics that you need to know: turning the Mac on and getting connected; using the keyboard and mouse; working with files and folders; navigate around the Mac desktop and OS X Lion; setting up an Inter

  13. MAC Layer Hurdles in BSNs

    CERN Document Server

    Ullah, Sana; Choi, Young-Woo; Lee, Hyung-Soo; Kwak, Kyung Sup

    2009-01-01

    The last few decades have seen considerable research progress in microelectronics and integrated circuits, system-on-chip design, wireless communication, and sensor technology. This progress has enabled the seamless integration of autonomous wireless sensor nodes around a human body to create a Body Sensor Network (BSN). The development of a proactive and ambulatory BSN induces a number of enormous issues and challenges. This paper presents the technical hurdles during the design and implementation of a low-power Medium Access Control (MAC) protocol for in-body and on-body sensor networks. We analyze the performance of IEEE 802.15.4 protocol for the on-body sensor network. We also provide a comprehensive insight into the heterogeneous characteristics of the in-body sensor network. A low-power technique called Pattern-Based Wake-up Table is proposed to handle the normal traffic in a BSN. The proposed technique provides a reliable solution towards low-power communication in the in-body sensor network.

  14. iMac pocket genius

    CERN Document Server

    Hart-Davis, Guy

    2010-01-01

    If you want to get the very most out of your iMac, put this savvy Portable Genius guide to work. Want to make the most of the new Magic Mouse and the latest iLife apps? Set up a wireless network using your iMac's AirPort card? Watch television on your iMac, or show iMac videos and movies on your television? You'll find cool and useful Genius tips, full-color screenshots, and pages of easy-to-access shortcuts and tools that will save you time and let you enjoy your iMac to the max.

  15. Effectiveness of AODV Protocol under Hidden Node Environment

    Science.gov (United States)

    Garg, Ruchi; Sharma, Himanshu; Kumar, Sumit

    IEEE 802.11 is a standard for mobile ad hoc networks (MANET), implemented with various different protocols. Ad Hoc on Demand Distance Vector Routing (AODV) is one of the several protocols of IEEE 802.11, intended to provide various Quality of Service (QOS) parameters under acceptable range. To avoid the collision and interference the MAC protocol has only two solutions, one, to sense the physical carrier and second, to use the RTS/CTS handshake mechanism. But with the help of these methods AODV is not free from the problem of hidden nodes like other several protocols. Under the hidden node environment, performance of AODV depends upon various factors. The position of receiver and sender among the other nodes is very crucial and it affects the performance. Under the various situations the AODV is simulated with the help of NS2 and the outcomes are discussed.

  16. Monolithic MACS micro resonators

    Science.gov (United States)

    Lehmann-Horn, J. A.; Jacquinot, J.-F.; Ginefri, J. C.; Bonhomme, C.; Sakellariou, D.

    2016-10-01

    Magic Angle Coil Spinning (MACS) aids improving the intrinsically low NMR sensitivity of heterogeneous microscopic samples. We report on the design and testing of a new type of monolithic 2D MACS resonators to overcome known limitations of conventional micro coils. The resonators' conductors were printed on dielectric substrate and tuned without utilizing lumped element capacitors. Self-resonance conditions have been computed by a hybrid FEM-MoM technique. Preliminary results reported here indicate robust mechanical stability, reduced eddy currents heating and negligible susceptibility effects. The gain in B1 /√{ P } is in agreement with the NMR sensitivity enhancement according to the principle of reciprocity. A sensitivity enhancement larger than 3 has been achieved in a monolithic micro resonator inside a standard 4 mm rotor at 500 MHz. These 2D resonators could offer higher performance micro-detection and ease of use of heterogeneous microscopic substances such as biomedical samples, microscopic specimens and thin film materials.

  17. MacBook for dummies

    CERN Document Server

    Chambers , Mark L

    2014-01-01

    Make friends with your MacBook the fun and easy way! Ultra-light, ultra-fast, and ultra-powerful, the MacBook is the coolest laptop in town, and longtime Mac guru Mark L. Chambers is just the guy to help you get to know your MacBook in no time. Take a closer look at the latest features, get the lowdown on OS X, unleash your creative forces with iLife, take care of business with the iWork applications, and sync it all with iCloud with the expert advice in this bestselling MacBook guide. Whether this is your first MacBook or your first laptop, period, you''ll learn to navigate the Mac desktop, c

  18. Macs For Dummies, Pocket Edition

    CERN Document Server

    Baig, Edward C

    2011-01-01

    The fun and easy way to make the most of your wonderful Mac. Simply Mac-nificent — all the cool things your Mac can do! This handy guide helps you figure out the nuts and bolts of your Mac. Navigate the Mac desktop, use the Safari Web browser to surf the Internet, e-mail photos to friends and family, create and print documents, rip audio CDs, and more. The fun begins right here!. Open the book and find: How to set up and configure your Mac; Tips for getting around on the Mac desktop; Steps for setting up an e-mail account and browsing the Internet; Details about the free programs that come wit

  19. iMac portable genius

    CERN Document Server

    Hart-Davis, Guy

    2010-01-01

    The most up-to-date coverage on the latest iMac advice, tools, and shortcuts Cool and useful tips, full-color screenshots, and savvy advice show you how to get the most out of your iMac. Fully updated to cover the iMac's latest features and capabilities, this guide is packed with indispensible information on iLife '09 and Mac OS X Snow Leopard, and shows you how to customize your iMac in a way that it will work best for you.Explores all the bells and whistles of the iMac, including the new Magic Mouse, iLife apps such as iPhoto and iMovie, and Mac OS X Snow LeopardShows yo

  20. Link-layer jamming attacks on S-MAC

    OpenAIRE

    Law, Yee Wei; Hartel, Pieter; Hartog, den, D.N.; Havinga, Paul

    2005-01-01

    We argue that among denial-of-service (DoS) attacks, link-layer jamming is a more attractive option to attackers than radio jamming is. By exploiting the semantics of the link-layer protocol (aka MAC protocol), an attacker can achieve better efficiency than blindly jamming the radio signals alone. In this paper, we investigate some jamming attacks on S-MAC, the level of effectiveness and efficiency the attacks can potentially achieve, and a countermeasure that can be implemented against one o...

  1. Energy-Efficiency Analysis of a Distributed Queuing Medium Access Control Protocol for Biomedical Wireless Sensor Networks in Saturation Conditions

    Directory of Open Access Journals (Sweden)

    Christos Verikoukis

    2011-01-01

    Full Text Available The aging population and the high quality of life expectations in our society lead to the need of more efficient and affordable healthcare solutions. For this reason, this paper aims for the optimization of Medium Access Control (MAC protocols for biomedical wireless sensor networks or wireless Body Sensor Networks (BSNs. The hereby presented schemes always have in mind the efficient management of channel resources and the overall minimization of sensors’ energy consumption in order to prolong sensors’ battery life. The fact that the IEEE 802.15.4 MAC does not fully satisfy BSN requirements highlights the need for the design of new scalable MAC solutions, which guarantee low-power consumption to the maximum number of body sensors in high density areas (i.e., in saturation conditions. In order to emphasize IEEE 802.15.4 MAC limitations, this article presents a detailed overview of this de facto standard for Wireless Sensor Networks (WSNs, which serves as a link for the introduction and initial description of our here proposed Distributed Queuing (DQ MAC protocol for BSN scenarios. Within this framework, an extensive DQ MAC energy-consumption analysis in saturation conditions is presented to be able to evaluate its performance in relation to IEEE 802.5.4 MAC in highly dense BSNs. The obtained results show that the proposed scheme outperforms IEEE 802.15.4 MAC in average energy consumption per information bit, thus providing a better overall performance that scales appropriately to BSNs under high traffic conditions. These benefits are obtained by eliminating back-off periods and collisions in data packet transmissions, while minimizing the control overhead.

  2. Energy-efficiency analysis of a distributed queuing medium access control protocol for biomedical wireless sensor networks in saturation conditions.

    Science.gov (United States)

    Otal, Begonya; Alonso, Luis; Verikoukis, Christos

    2011-01-01

    The aging population and the high quality of life expectations in our society lead to the need of more efficient and affordable healthcare solutions. For this reason, this paper aims for the optimization of Medium Access Control (MAC) protocols for biomedical wireless sensor networks or wireless Body Sensor Networks (BSNs). The hereby presented schemes always have in mind the efficient management of channel resources and the overall minimization of sensors' energy consumption in order to prolong sensors' battery life. The fact that the IEEE 802.15.4 MAC does not fully satisfy BSN requirements highlights the need for the design of new scalable MAC solutions, which guarantee low-power consumption to the maximum number of body sensors in high density areas (i.e., in saturation conditions). In order to emphasize IEEE 802.15.4 MAC limitations, this article presents a detailed overview of this de facto standard for Wireless Sensor Networks (WSNs), which serves as a link for the introduction and initial description of our here proposed Distributed Queuing (DQ) MAC protocol for BSN scenarios. Within this framework, an extensive DQ MAC energy-consumption analysis in saturation conditions is presented to be able to evaluate its performance in relation to IEEE 802.5.4 MAC in highly dense BSNs. The obtained results show that the proposed scheme outperforms IEEE 802.15.4 MAC in average energy consumption per information bit, thus providing a better overall performance that scales appropriately to BSNs under high traffic conditions. These benefits are obtained by eliminating back-off periods and collisions in data packet transmissions, while minimizing the control overhead.

  3. Analyzing the effect of routing protocols on media access control protocols in radio networks

    Energy Technology Data Exchange (ETDEWEB)

    Barrett, C. L. (Christopher L.); Drozda, M. (Martin); Marathe, A. (Achla); Marathe, M. V. (Madhav V.)

    2002-01-01

    We study the effect of routing protocols on the performance of media access control (MAC) protocols in wireless radio networks. Three well known MAC protocols: 802.11, CSMA, and MACA are considered. Similarly three recently proposed routing protocols: AODV, DSR and LAR scheme 1 are considered. The experimental analysis was carried out using GloMoSim: a tool for simulating wireless networks. The main focus of our experiments was to study how the routing protocols affect the performance of the MAC protocols when the underlying network and traffic parameters are varied. The performance of the protocols was measured w.r.t. five important parameters: (i) number of received packets, (ii) average latency of each packet, (iii) throughput (iv) long term fairness and (v) number of control packets at the MAC layer level. Our results show that combinations of routing and MAC protocols yield varying performance under varying network topology and traffic situations. The result has an important implication; no combination of routing protocol and MAC protocol is the best over all situations. Also, the performance analysis of protocols at a given level in the protocol stack needs to be studied not locally in isolation but as a part of the complete protocol stack. A novel aspect of our work is the use of statistical technique, ANOVA (Analysis of Variance) to characterize the effect of routing protocols on MAC protocols. This technique is of independent interest and can be utilized in several other simulation and empirical studies.

  4. iMac for dummies

    CERN Document Server

    Chambers, Mark L

    2014-01-01

    Do it all with your iMac and this bestselling For Dummies guide! You're still a little giddy from finally scoring your new iMac, and you can't wait to get started. Even if you're already in love with your iMac, it helps to have a little guidance to really get the most out of this ultimate all-in-one computer. This updated edition of iMac For Dummies is the ideal way to learn the iMac fundamentals from setting up and personalizing your machine to importing files, making FaceTime video calls, surfing the web, using your favorite programs and apps, and everything in between. Trusted Mac guru Mark

  5. Learn Excel 2011 for Mac

    CERN Document Server

    Hart-Davis, Guy

    2011-01-01

    Microsoft Excel 2011 for Mac OS X is a powerful application, but many of its most impressive features can be difficult to find. Learn Excel 2011 for Mac by Guy Hart-Davis is a practical, hands-on approach to learning all of the details of Excel 2011 in order to get work done efficiently on Mac OS X. From using formulas and functions to creating databases, from analyzing data to automating tasks, you'll learn everything you need to know to put this powerful application to use for a variety of tasks. What you'll learn * The secrets of the Excel for Mac interface! * How to create effective workbo

  6. ETEEM- Extended Traffic Aware Energy Efficient MAC Scheme for WSNs

    Directory of Open Access Journals (Sweden)

    Younas Khan

    2016-11-01

    Full Text Available Idle listening issue arises when a sensor node listens to medium despite the absence of data which results in consumption of energy. ETEEM is a variant of Traffic Aware Energy Efficient MAC protocol (TEEM which focuses on energy optimization due to reduced idle listening time and much lesser overhead on energy sources. It uses a novel scheme for using idle listening time of sensor nodes. The nodes are only active for small amount of time and most of the time, will be in sleep mode when no data is available. ETEEM reduces energy at byte level and uses a smaller byte packet called FLAG replacing longer byte SYNC packets of S-MAC and SYNCrts of TEEM respectively. It also uses a single acknowledgement packet per data set hence reducing energy while reducing frequency of the acknowledgment frames sent. The performance of ETEEM is 70% better comparative to other under-consideration MAC protocols.

  7. Energy Efficient MAC for Wireless Sensor Networks

    Directory of Open Access Journals (Sweden)

    Pekka KOSKELA

    2010-10-01

    Full Text Available This paper considers an overlay solution for asynchronous Medium Access Control (MAC protocols in a duty-cycled wireless sensor network (WSN. The solution extends sleeping times and corrects time drift when the sampling rate is low. The sleeping time is adjusted according to the requisite data sampling rate and the delay requirements of the prevailing application. This and the time drift correction considerably reduced idle listening and thus also decreased power consumption. When the power consumption is reduced, the life of wireless sensor nodes extends.

  8. A USER-DEPENDENT PERFECT-SCHEDULING MULTIPLE ACCESS PROTOCOL FOR VOICE-DATA INTEGRATION IN WIRELESS NETWORKS

    Institute of Scientific and Technical Information of China (English)

    Zhou Yajian; Li Jiandong; Liu Kai

    2002-01-01

    A novel Multiple Access Control (MAC) protocol - User-dependent Perfect-scheduling Multiple Access (UPMA) protocol, which supports joint transmission of voice and data packets,is proposed. By this protocol, the bandwidth can be allocated dynamically to the uplink and downlink traffic with on-demand assignment and the transmission of Mobile Terminals (MTs)can be perfectly scheduled by means of polling. Meanwhile, a unique frame structure is designed to guarantee Quality of Service (QoS) in voice traffic supporting. An effective collision resolution algorithm is also proposed to guarantee rapid channel access for activated MTs. Finally, performance of UPMA protocol is evaluated by simulation and compared with MPRMA protocol.Simulation results show that UPMA protocol has better performance.

  9. MAC Support for High Density Wireless Sensor Networks

    NARCIS (Netherlands)

    Taddia, C.; Meratnia, Nirvana; van Hoesel, L.F.W.; Mazzini, G.; Havinga, Paul J.M.

    Large scale and high density networks of tiny sensor nodes offer promising solutions for event detection and actuating applications. In this paper we address the effect of high density of wireless sensor network performance with a specific MAC protocol, the Lightweight Medium Access Control (LMAC).

  10. Ellen MacArthur

    Institute of Scientific and Technical Information of China (English)

    Teodora; Lazarova

    2006-01-01

    Just over a year since breaking the round theworld solo record on board her 75 foot trimaranB&O,Ellen MacArthur embarked on a newventure:the Asian Record Circuit 2006,incorpo-rating the ‘Tour Of China’,and bringing a differ-ent set of challenges into new territories.Wespoke to Ellen and her team during their recent(April)stopover in Oingdao.When did you start sailing and what inspiredyou(you grew up in Derbyshire,in the UK,quite far away from the water)?I was introduced to sailing by my Aunt Thea ona small sailing boat called Cabaret.We wentsailing along the east coast of EngLand andbefore I knew it,I was hooked on sailing.I wasso inspired that when I was at school,I saved

  11. Macs for seniors for dummies

    CERN Document Server

    Chambers, Mark L

    2009-01-01

    Over 50 and thinking about getting your first computer? A user-friendly Mac is a great choice, and Macs For Seniors For Dummies walks you through choosing one and learning to use it. You won't even need your grandchildren to help! Macs For Seniors For Dummies introduces you to all the basic things you may not have encountered before-how to use the keyboard and mouse, work with files and folders, navigate around the Mac OS X desktop, set up an Internet connection, and much more. You'll learn to:Choose the Mac that's right for you, set it up, run programs and manage files, and hook up a printerU

  12. iMac for dummies

    CERN Document Server

    Chambers, Mark L

    2012-01-01

    The bestselling guide to the ultimate all-in-one computer—now updated and revised throughout! If you're looking for speed, performance, and power, the iMac is the ultimate all-in-one computer. From its superior performance, powerful operating system, and amazing applications, the iMac is one awesome machine, and the fun, friendly, and approachable style of iMac For Dummies is an ideal way to get started with the basics. You'll learn the fundamentals of the iMac including setting up and customizing your iMac and the software that comes with it, importing files from your old computer, send

  13. Increasing the quantity and quality of searching for current best evidence to answer clinical questions: protocol and intervention design of the MacPLUS FS Factorial Randomized Controlled Trials.

    Science.gov (United States)

    Agoritsas, Thomas; Iserman, Emma; Hobson, Nicholas; Cohen, Natasha; Cohen, Adam; Roshanov, Pavel S; Perez, Miguel; Cotoi, Chris; Parrish, Rick; Pullenayegum, Eleanor; Wilczynski, Nancy L; Iorio, Alfonso; Haynes, R Brian

    2014-09-20

    Finding current best evidence for clinical decisions remains challenging. With 3,000 new studies published every day, no single evidence-based resource provides all answers or is sufficiently updated. McMaster Premium LiteratUre Service--Federated Search (MacPLUS FS) addresses this issue by looking in multiple high quality resources simultaneously and displaying results in a one-page pyramid with the most clinically useful at the top. Yet, additional logistical and educational barriers need to be addressed to enhance point-of-care evidence retrieval. This trial seeks to test three innovative interventions, among clinicians registered to MacPLUS FS, to increase the quantity and quality of searching for current best evidence to answer clinical questions. In a user-centered approach, we designed three interventions embedded in MacPLUS FS: (A) a web-based Clinical Question Recorder; (B) an Evidence Retrieval Coach composed of eight short educational videos; (C) an Audit, Feedback and Gamification approach to evidence retrieval, based on the allocation of 'badges' and 'reputation scores.' We will conduct a randomized factorial controlled trial among all the 904 eligible medical doctors currently registered to MacPLUS FS at the hospitals affiliated with McMaster University, Canada. Postgraduate trainees (n=429) and clinical faculty/staff (n=475) will be randomized to each of the three following interventions in a factorial design (AxBxC). Utilization will be continuously recorded through clinicians’ accounts that track logins and usage, down to the level of individual keystrokes. The primary outcome is the rate of searches per month per user during the six months of follow-up. Secondary outcomes, measured through the validated Impact Assessment Method questionnaire, include: utility of answers found (meeting clinicians’ information needs), use (application in practice), and perceived usefulness on patient outcomes. Built on effective models for the point

  14. Delay analysis of an integrated voice and data access protocol with collision detection for multimedia satellite networks

    Science.gov (United States)

    Poon, Charles C. K.; Suda, Tatsuya

    1992-03-01

    The novel multiple-access scheme for multimedia satellite networks presented is based on a combination of FDMA and TDMA, integrating both circuit and packet-switching techniques. While the circuit-switching method is used to transmit such stream-type traffic as real-time voice communications, packet-switching is used to transmit such 'bursty' traffic as interactive data. A ground radio network is assumed for control signaling; the tone sense multiple access/partial collision detection scheme is implemented on this network to enhance the integrated access scheme's performance.

  15. Gotcha! Macs lose their innocence

    CERN Multimedia

    Computer Security Team

    2012-01-01

    Still believe your Mac is secure because Microsoft PCs fall prey to viruses and worms but Macs don’t? Time to wake up! This year has seen the first major compromise of Macs worldwide*. How is yours doing?   The “Flashback” Trojan is affecting Apple’s own variant of Java and compromises Macs via so-called drive-by infections, i.e. when you visit an appropriately prepared (infected!) website - and this might not necessarily be a site with questionable contents, but could well be a popular, reputable one. Security Companies worldwide have been monitoring this particular Trojan for a while and have estimated that more than half a million Macs were compromised. Connected to a few central command and control servers, the compromised Macs were then supporting the malicious activity of the bad guys! Fortunately, the security companies have now been able to take over those command and control servers and stop their destructive drive. So, Mac users, face the f...

  16. Java and Mac OS X

    CERN Document Server

    Davis, T Gene

    2010-01-01

    Learn the guidelines of integrating Java with native Mac OS X applications with this Devloper Reference book. Java is used to create nearly every type of application that exists and is one of the most required skills of employers seeking computer programmers. Java code and its libraries can be integrated with Mac OS X features, and this book shows you how to do just that. You'll learn to write Java programs on OS X and you'll even discover how to integrate them with the Cocoa APIs.: Shows how Java programs can be integrated with any Mac OS X feature, such as NSView widgets or screen savers; Re

  17. Towards a Collision-Free WLAN: Dynamic Parameter Adjustment in CSMA/E2CA

    Directory of Open Access Journals (Sweden)

    Bellalta Boris

    2011-01-01

    Full Text Available Carrier sense multiple access with enhanced collision avoidance (CSMA/ECA is a distributed MAC protocol that allows collision-free access to the medium in WLANs. The only difference between CSMA/ECA and the well-known CSMA/CA is that the former uses a deterministic backoff after successful transmissions. Collision-free operation is reached after a transient state during which some collisions may occur. This paper shows that the duration of the transient state can be shortened by appropriately setting the contention parameters. Standard absorbing Markov chain theory is used to describe the behaviour of the system in the transient state and to predict the expected number of slots to reach the collision-free operation. The paper also introduces CSMA/E2CA, in which a deterministic backoff is used two consecutive times after a successful transmission. CSMA/E2CA converges quicker to collision-free operation and delivers higher performance than CSMA/ECA, specially in harsh wireless scenarios with high frame-error rates. The last part of the paper addresses scenarios with a large number of contenders. We suggest dynamic parameter adjustment techniques to accommodate a varying (and potentially high number of contenders. The effectiveness of these adjustments in preventing collisions is validated by means of simulation.

  18. Mac Programming for Absolute Beginners

    CERN Document Server

    Wang, Wallace

    2011-01-01

    Want to learn how to program on your Mac? Not sure where to begin? Best-selling author Wallace Wang will explain how to get started with Cocoa, Objective-C, and Xcode. Whether you are an experienced Windows coder moving to the Mac, or you are completely new to programming, you'll see how the basic design of a Mac OS X program works, how Objective-C differs from other languages you may have used, and how to use the Xcode development environment. Most importantly, you'll learn how to use elements of the Cocoa framework to create windows, store data, and respond to users in your own Mac programs.

  19. MacBook portable genius

    CERN Document Server

    Miser, Brad

    2008-01-01

    The Genius is in. You don't have to be a genius to use a MacBook. But if you want to get the very most out of yours, put this savvy Portable Genius guide to work. Want to connect your MacBook to other Macs? Use Expose to its fullest potential? Troubleshoot? You'll find cool and useful Genius tips, insider secrets, full-color screenshots, and pages of easy-to-access shortcuts and tools that will save you loads of time and make your MacBook IQ soar. Portable GENIUS Fun, hip, and straightforward, the new Portable Genius series gives forward-thinking Apple users useful informat

  20. Mac mini真体验

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    2005年,Mac mini首次登场,众所周知,苹果的模具更换的并不频繁,在外貌没有大幅改变的情况下,迄今为止,Mac mini实际上已经更新了7代。最新的Mac mini的工业设计实际上延续了2008年开始的Unibody一体成型铝合金机身设计与其他Mac在外观上保持了一致的元素。更小的Mac mini看起来更加性感诱人,那么,你需要它么?

  1. Comparison between MACAW and T_Lohi protocols for underwater networks.

    Directory of Open Access Journals (Sweden)

    Erik Ortiz Guerra

    2011-02-01

    Full Text Available The development of underwater networks presents great challenges, most of which are related to the complexity of the communication channel. The main difficulties to face in the underwater channel are the restricted bandwidth and the low propagation speed. Due to these difficulties, it is necessary the development of new and more competent communication protocols in order to obtain higher performance and minimize the energy consumption. Therefore, this paper presents a comparative evaluation between two medium access controls (MAC: MACAW and T_Lohi. Both protocols are based on random access mechanism, the first uses request to send (RTS; clear to send (CTS and acknowledgement (ACK messages to regulate transmissions while the second uses short duration tones which can be detected instantaneously. Thus, this study focuses on the performance, collisions and efficiency of these protocols in order to reserve the communication channel, whereby it highlights the advantages and deficiencies of each protocol in the underwater communication networks.

  2. 无线传感器网络动态节能信道接入协议%A Dynamic, Energy-Efficient MAC Protocol for Wireless Sensor Networks

    Institute of Scientific and Technical Information of China (English)

    万江文; 周莹

    2006-01-01

    为了使无线传感器网络移动节点加入时能快速地建立连接并且能量消耗较低,提出一种动态、节能的信道接入控制协议DEE-MAC.该协议以一种新颖的方式在TDMA的基础上叠加了动态分簇和优先级竞争簇头机制,在移动和静止场景中,既有最低性能保障,又有较高信道利用率.仿真结果表明,有移动节点加入时,DEE-MAC协议在数据吞吐量、延时以及丢包率方面比SMAC协议都有明显改善.

  3. Fiverr MacGyver

    Science.gov (United States)

    Hut, Rolf; van de Giesen, Nick; Larson, Martha

    2014-05-01

    Crowdsourcing has become popular over the past years, also for scientific endeavors. There are many Citizen Science projects and crowdfunding platforms, such as Kickstarter, that are make helpful contributions to moving environmental science forward. An interesting underused source of useful crowd-derived contributions to research is the website Fiverr.com. On this platform, thousands of people, acting as small-scale freelance contractors, offer their skills in the form of services. The platform offers a chance for people to take a hobby, skill, or pastime and make it something more by reaching out to a wider audience and by receiving a payment in return for services. As is typical of other crowdsourcing platforms, the tasks are small and usually self contained. As the name Fiverr suggests, offers start at US5 to provide a particular service. Services offered range from graphic design, to messages sung or spoken with various styles or accents, to complete apps for Android or iPhone. Skill providers on the platform can accept a range of variation of definition in the tasks, some can be described in general terms, for others it is more appropriate to provide examples. Fiverr provides a central location for those offering skills and those needing services to find each other, it makes it possible to communicate and exchange files, to make payments, and it provides support for resolving disputes. In all cases, it is important to keep expectations aligned with the nature of the platform: quality can and will vary. Ultimately, the critical contribution of Fiverr is not to replace professional services or otherwise save money, but rather to provide access to a large group of people with specialized skills who are able to make a contribution on short notice. In the context of this session, it can be considered a pool of people with MacGyver skills lying in wait of a MacGyyer task to attack. There are many ways in which Fiverr tasks, which are called 'gigs', can be useful in

  4. MacBook Teach Yourself VISUALLY

    CERN Document Server

    Miser, Brad

    2010-01-01

    Like the MacBook itself, Teach Yourself VISUALLY MacBook, Second Edition is designed to be visually appealing, while providing excellent functionality at the same time. By using this book, MacBook users will be empowered to do everyday tasks quickly and easily. From such basic steps as powering on or shutting down the MacBook, working on the Mac desktop with the Dashboard and its widgets to running Windows applications, Teach Yourself VISUALLY MacBook, Second Edition covers all the vital information and provides the help and support a reader needs—in many ways it's like having a Mac Genius at

  5. Switching to a Mac portable genius

    CERN Document Server

    McFedries, Paul

    2011-01-01

    Switching from a PC to a Mac is a breeze with this book Anyone considering making the move to Mac from the Windows world will find this book smoothes the way. While Macs are famous for ease of use, there are fundamental differences in Mac and PC ways of thinking, plus there?s the hassle of moving files, calendars, and other essential data from one platform to another. This guide lays out all the information, explains basic Mac procedures for the newcomer, offers great tips on data-sharing (including running Windows applications on a Mac), and provides everything the new Mac user needs to move

  6. Switching to a Mac For Dummies

    CERN Document Server

    Reinhold, Arnold

    2011-01-01

    Learn how to make the switch from PC to Mac a completely smooth transition The number of Mac users continues to increase significantly each year. If you are one of those people and are eager but also anxious about making the switch, then fear not! This friendly guide skips the jargon to deliver you an easy-to-read, understandable introduction to the Macintosh computer. Computer guru Arnold Reinhold walks you through the Mac OS, user interface, and icons. You'll learn how to set up your Mac, move your files from your PC to your Mac, switch applications, get your Mac online, network your Mac, se

  7. MQ-MAC: A Multi-Constrained QoS-Aware Duty Cycle MAC for Heterogeneous Traffic in Wireless Sensor Networks

    Science.gov (United States)

    Monowar, Muhammad Mostafa; Rahman, Md. Obaidur; Hong, Choong Seon; Lee, Sungwon

    2010-01-01

    Energy conservation is one of the striking research issues now-a-days for power constrained wireless sensor networks (WSNs) and hence, several duty-cycle based MAC protocols have been devised for WSNs in the last few years. However, assimilation of diverse applications with different QoS requirements (i.e., delay and reliability) within the same network also necessitates in devising a generic duty-cycle based MAC protocol that can achieve both the delay and reliability guarantee, termed as multi-constrained QoS, while preserving the energy efficiency. To address this, in this paper, we propose a Multi-constrained QoS-aware duty-cycle MAC for heterogeneous traffic in WSNs (MQ-MAC). MQ-MAC classifies the traffic based on their multi-constrained QoS demands. Through extensive simulation using ns-2 we evaluate the performance of MQ-MAC. MQ-MAC provides the desired delay and reliability guarantee according to the nature of the traffic classes as well as achieves energy efficiency. PMID:22163439

  8. MQ-MAC: a multi-constrained QoS-aware duty cycle MAC for heterogeneous traffic in wireless sensor networks.

    Science.gov (United States)

    Monowar, Muhammad Mostafa; Rahman, Md Obaidur; Hong, Choong Seon; Lee, Sungwon

    2010-01-01

    Energy conservation is one of the striking research issues now-a-days for power constrained wireless sensor networks (WSNs) and hence, several duty-cycle based MAC protocols have been devised for WSNs in the last few years. However, assimilation of diverse applications with different QoS requirements (i.e., delay and reliability) within the same network also necessitates in devising a generic duty-cycle based MAC protocol that can achieve both the delay and reliability guarantee, termed as multi-constrained QoS, while preserving the energy efficiency. To address this, in this paper, we propose a Multi-constrained QoS-aware duty-cycle MAC for heterogeneous traffic in WSNs (MQ-MAC). MQ-MAC classifies the traffic based on their multi-constrained QoS demands. Through extensive simulation using ns-2 we evaluate the performance of MQ-MAC. MQ-MAC provides the desired delay and reliability guarantee according to the nature of the traffic classes as well as achieves energy efficiency.

  9. MQ-MAC: A Multi-Constrained QoS-Aware Duty Cycle MAC for Heterogeneous Traffic in Wireless Sensor Networks

    Directory of Open Access Journals (Sweden)

    Sungwon Lee

    2010-11-01

    Full Text Available Energy conservation is one of the striking research issues now-a-days for power constrained wireless sensor networks (WSNs and hence, several duty-cycle based MAC protocols have been devised for WSNs in the last few years. However, assimilation of diverse applications with different QoS requirements (i.e., delay and reliability within the same network also necessitates in devising a generic duty-cycle based MAC protocol that can achieve both the delay and reliability guarantee, termed as multi-constrained QoS, while preserving the energy efficiency. To address this, in this paper, we propose a Multi-constrained QoS-aware duty-cycle MAC for heterogeneous traffic in WSNs (MQ-MAC. MQ-MAC classifies the traffic based on their multi-constrained QoS demands. Through extensive simulation using ns-2 we evaluate the performance of MQ-MAC. MQ-MAC provides the desired delay and reliability guarantee according to the nature of the traffic classes as well as achieves energy efficiency.

  10. Distance Geometry Protocol to Generate Conformations of Natural Products to Structurally Interpret Ion Mobility-Mass Spectrometry Collision Cross Sections

    Science.gov (United States)

    2015-01-01

    Ion mobility-mass spectrometry (IM-MS) allows the separation of ionized molecules based on their charge-to-surface area (IM) and mass-to-charge ratio (MS), respectively. The IM drift time data that is obtained is used to calculate the ion-neutral collision cross section (CCS) of the ionized molecule with the neutral drift gas, which is directly related to the ion conformation and hence molecular size and shape. Studying the conformational landscape of these ionized molecules computationally provides interpretation to delineate the potential structures that these CCS values could represent, or conversely, structural motifs not consistent with the IM data. A challenge in the IM-MS community is the ability to rapidly compute conformations to interpret natural product data, a class of molecules exhibiting a broad range of biological activity. The diversity of biological activity is, in part, related to the unique structural characteristics often observed for natural products. Contemporary approaches to structurally interpret IM-MS data for peptides and proteins typically utilize molecular dynamics (MD) simulations to sample conformational space. However, MD calculations are computationally expensive, they require a force field that accurately describes the molecule of interest, and there is no simple metric that indicates when sufficient conformational sampling has been achieved. Distance geometry is a computationally inexpensive approach that creates conformations based on sampling different pairwise distances between the atoms within the molecule and therefore does not require a force field. Progressively larger distance bounds can be used in distance geometry calculations, providing in principle a strategy to assess when all plausible conformations have been sampled. Our results suggest that distance geometry is a computationally efficient and potentially superior strategy for conformational analysis of natural products to interpret gas-phase CCS data. PMID:25360896

  11. Mac OS X Lion在Mac App Store上线

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    2011年7月20日,Apple宣布具有超过250种新功能的世界最先进操作系统的第八个重要版本Mac OS X Lion今天在Mac App StoreTM推出并可进行下载,价格为29.99美元。Lion的诸多超强功能包括:全新Multi-Touch手势;全系统支持全屏应用程序;

  12. Comprehensive Peptide Ion Structure Studies Using Ion Mobility Techniques: Part 1. An Advanced Protocol for Molecular Dynamics Simulations and Collision Cross-Section Calculation

    Science.gov (United States)

    Ghassabi Kondalaji, Samaneh; Khakinejad, Mahdiar; Tafreshian, Amirmahdi; J. Valentine, Stephen

    2017-02-01

    Collision cross-section (CCS) measurements with a linear drift tube have been utilized to study the gas-phase conformers of a model peptide (acetyl-PAAAAKAAAAKAAAAKAAAAK). Extensive molecular dynamics (MD) simulations have been conducted to derive an advanced protocol for the generation of a comprehensive pool of in-silico structures; both higher energy and more thermodynamically stable structures are included to provide an unbiased sampling of conformational space. MD simulations at 300 K are applied to the in-silico structures to more accurately describe the gas-phase transport properties of the ion conformers including their dynamics. Different methods used previously for trajectory method (TM) CCS calculation employing the Mobcal software [1] are evaluated. A new method for accurate CCS calculation is proposed based on clustering and data mining techniques. CCS values are calculated for all in-silico structures, and those with matching CCS values are chosen as candidate structures. With this approach, more than 300 candidate structures with significant structural variation are produced; although no final gas-phase structure is proposed here, in a second installment of this work, gas-phase hydrogen deuterium exchange data will be utilized as a second criterion to select among these structures as well as to propose relative populations for these ion conformers. Here the need to increase conformer diversity and accurate CCS calculation is demonstrated and the advanced methods are discussed.

  13. Comprehensive Peptide Ion Structure Studies Using Ion Mobility Techniques: Part 1. An Advanced Protocol for Molecular Dynamics Simulations and Collision Cross-Section Calculation.

    Science.gov (United States)

    Ghassabi Kondalaji, Samaneh; Khakinejad, Mahdiar; Tafreshian, Amirmahdi; J Valentine, Stephen

    2017-05-01

    Collision cross-section (CCS) measurements with a linear drift tube have been utilized to study the gas-phase conformers of a model peptide (acetyl-PAAAAKAAAAKAAAAKAAAAK). Extensive molecular dynamics (MD) simulations have been conducted to derive an advanced protocol for the generation of a comprehensive pool of in-silico structures; both higher energy and more thermodynamically stable structures are included to provide an unbiased sampling of conformational space. MD simulations at 300 K are applied to the in-silico structures to more accurately describe the gas-phase transport properties of the ion conformers including their dynamics. Different methods used previously for trajectory method (TM) CCS calculation employing the Mobcal software [1] are evaluated. A new method for accurate CCS calculation is proposed based on clustering and data mining techniques. CCS values are calculated for all in-silico structures, and those with matching CCS values are chosen as candidate structures. With this approach, more than 300 candidate structures with significant structural variation are produced; although no final gas-phase structure is proposed here, in a second installment of this work, gas-phase hydrogen deuterium exchange data will be utilized as a second criterion to select among these structures as well as to propose relative populations for these ion conformers. Here the need to increase conformer diversity and accurate CCS calculation is demonstrated and the advanced methods are discussed. Graphical Abstract ᅟ.

  14. Comprehensive Peptide Ion Structure Studies Using Ion Mobility Techniques: Part 1. An Advanced Protocol for Molecular Dynamics Simulations and Collision Cross-Section Calculation

    Science.gov (United States)

    Ghassabi Kondalaji, Samaneh; Khakinejad, Mahdiar; Tafreshian, Amirmahdi; J. Valentine, Stephen

    2017-05-01

    Collision cross-section (CCS) measurements with a linear drift tube have been utilized to study the gas-phase conformers of a model peptide (acetyl-PAAAAKAAAAKAAAAKAAAAK). Extensive molecular dynamics (MD) simulations have been conducted to derive an advanced protocol for the generation of a comprehensive pool of in-silico structures; both higher energy and more thermodynamically stable structures are included to provide an unbiased sampling of conformational space. MD simulations at 300 K are applied to the in-silico structures to more accurately describe the gas-phase transport properties of the ion conformers including their dynamics. Different methods used previously for trajectory method (TM) CCS calculation employing the Mobcal software [1] are evaluated. A new method for accurate CCS calculation is proposed based on clustering and data mining techniques. CCS values are calculated for all in-silico structures, and those with matching CCS values are chosen as candidate structures. With this approach, more than 300 candidate structures with significant structural variation are produced; although no final gas-phase structure is proposed here, in a second installment of this work, gas-phase hydrogen deuterium exchange data will be utilized as a second criterion to select among these structures as well as to propose relative populations for these ion conformers. Here the need to increase conformer diversity and accurate CCS calculation is demonstrated and the advanced methods are discussed.

  15. Office 2011 for Mac For Dummies

    CERN Document Server

    LeVitus, Bob

    2011-01-01

    Get started with Office 2011 for Mac and discover the creative possibilitiesThe leading suite of productivity software for the Mac, Microsoft Office helps users complete common business tasks, including word processing, e-mail, presentations, financial analysis, and much more. Office 2011 for Mac For Dummies is the perfect companion for Microsoft Office for Mac users upgrading to the newest version, new computer users, and those who may have switched from the Windows version of Office. Written by one of the most popular gurus in the Mac community, Bob "Dr. Mac" LeVitus, the book explains every

  16. Analytical Comparison of MAC Schemes for Energy Harvesting - Wireless Sensor Networks

    DEFF Research Database (Denmark)

    Fafoutis, Xenofon; Dragoni, Nicola

    2012-01-01

    MAC protocols for multi-hop WSNs have to address the challenge of coordinating duty-cycling transmitters with duty-cycling receivers. All the suggested protocols can be classified into three basic paradigms: the synchronization, the preamble and the beaconing paradigm. In this paper, we discuss...

  17. Approximate discrete time analysis of the hybrid Token-CDMA MAC system

    CSIR Research Space (South Africa)

    Liu, YS

    2007-09-01

    Full Text Available of the Hybrid Token-CDMA MAC System Yi Sheng Liu, Student Member, IEEE, Fambirai Takawira, Member, IEEE , and Hong Jun Xu, Member, IEEE Abstract— In this paper a hybrid Token-CDMA based medium access control (MAC) protocol is considered. The MAC scheme...Zulu-Natal, Howard College Campus. He received the BSc degree in 1984 from the University of Guilin Technology and the MSc degree from the Institute of Telecontrol and Telemeasure in Shi Jian Zhuang, 1989, and the PhD degree from the Beijing University...

  18. LEFT: A Latency and Energy Efficient Flexible TDMA Protocol for Wireless Sensor Networks

    Directory of Open Access Journals (Sweden)

    Sachin Gajjar

    2015-01-01

    Full Text Available This paper proposes latency and energy efficient flexible TDMA (LEFT, a medium access control (MAC combined with routing protocol for data gathering from number of source nodes to a master station (MS in a wireless sensor network (WSN. TDMA provides fairness, collision-free communication and reduces idle listening, which saves network energy. Data latency is reduced by allocating same transmission slots to nodes falling out of interference range of each other. Unlike a conventional TDMA, LEFT provides flexibility through slot seizing, wherein a non-holder of a slot can use slot when holder does not have data to send. This increases channel utilization and adaption to dynamic traffic patterns of WSN applications. Further, a node on a multi-hop path towards MS decides to participate in routing based on (i its location with respect to MS, to forward data in correct direction, (ii its current status of residual energy, to uniformly distribute energy across network, (iii its transit traffic load, to prevent local congestion, (iv its communication link quality, to guarantee reliable data delivery. This decision requires simple comparisons against thresholds, and thus is very simple to implement on energy, storage and computationally constrained nodes. LEFT also encompasses techniques to cater to link and node breakdowns. Experimental analysis of LEFT; Advertisement-based TDMA; Data gathering MAC; Energy Efficient Fast Forwarding and Cross layer MAC protocols using TI's EZ430-RF2500T nodes shows that LEFT is 65% more energy efficient compared to Cross layer MAC. Data latency of LEFT is 27 % less, delivery ratio is 17 % more and goodput is 11 % more compared to Cross layer MAC.

  19. Analysis of an Adaptive P-Persistent MAC Scheme for WLAN Providing Delay Fairness

    Science.gov (United States)

    Yen, Chih-Ming; Chang, Chung-Ju; Chen, Yih-Shen; Huang, Ching Yao

    The paper proposes and analyzes an adaptive p-persistent-based (APP) medium access control (MAC) scheme for IEEE 802.11 WLAN. The APP MAC scheme intends to support delay fairness for every station in each access, denoting small delay variance. It differentiates permission probabilities of transmission for stations which are incurred with various packet delays. This permission probability is designed as a function of the numbers of retransmissions and re-backoffs so that stations with larger packet delay are endowed with higher permission probability. Also, the scheme is analyzed by a Markov-chain analysis, where the collision probability, the system throughput, and the average delay are successfully obtained. Numerical results show that the proposed APP MAC scheme can attain lower mean delay and higher mean throughput. In the mean time, simulation results are given to justify the validity of the analysis, and also show that the APP MAC scheme can achieve more delay fairness than conventional algorithms.

  20. Investigation of Mycobacterium avium complex (MAC) in Australian commercial milk using qPCR.

    Science.gov (United States)

    Adhikari, Shraddha; Caro Tohme, Tanya; Whiley, Harriet

    2017-02-01

    This technical research communication describes the first study to use quantitative polymerase chain reaction (qPCR) to investigate the presence of Mycobacterium avium complex (MAC) in Australian pasteurised milk. MAC is the most common NTM responsible for human illnesses and includes M. avium subspecies paratuberculosis (MAP). MAC is a causative agent of lymphadenitis in children, with contaminated food and water considered as a likely source. As such the presence of MAC in milk would have public health significance. MAP has been linked to Crohn's disease and is also the causative agent of Johne's disease in cattle. Previous studies have detected MAP in pasteurised milk from Brazil, India, Czech Republic, USA, Argentina, UK, Iran, Ireland and the United Kingdom. This study investigated a total of 180 commercially available Australian pasteurised milk samples which were tested for MAC DNA in triplicate using PCR. All samples were negative for MAC DNA. An additional 14 milk samples were tested, incubated for 3 weeks at 37 °C to potentially increase the concentration of any viable MAC that may be present and then retested. All samples were again negative for MAC DNA. This could be due to concentrations below the limit of detection, limited sample size or could be reflective of the Australian biosecurity control protocols and surveillance of Johne's disease in ruminant animals.

  1. A concurrent transmission MAC protocol for power control in wireless sensor networks based on the non-cooperative game theory%基于非合作博弈功率控制的传感器网络并行传输MAC协议

    Institute of Scientific and Technical Information of China (English)

    杨国燕; 张国印; 关心

    2011-01-01

    针对传统的基于竞争或调度的MAC协议用于节点密集部署的无线传感器网络中,会出现较低的吞吐量和累计延迟等问题,利用节点密集部署的无线传感器网络中普遍存在的捕获效应对MAC协议性能的影响,提出了一种单信道模式下工作的并行传输的新型高效MAC协议——基于非合作博弈功率控制的并行传输MAC协议.该协议运用博弈理论中非合作不完全信息博弈算法模型,实现了多个节点在同一信道上采用最优功率进行并行传输.应用贝叶斯Nash均衡定理证明了该协议的基于博弈理论的功率控制算法的Nash均衡的存在性和唯一性.仿真实验证明该协议能够实现多个节点在干扰范围内并行地进行数据传输,能显著地提高网络吞吐量、减少数据传输延迟并实现能量的高效利用,有效提高信道资源的空间复用效率.%Considering that traditional competitive or scheduling MAC protocols are not suitable for wireless sensor networks with high-load and intensive nodes due to the occurrence of low throughput and accumulated delay when u-sing them, this paper proposes an efficient concurrent transmission MAC protocol for power control in wireless sensor networks based on the non-cooperative game theory that works in one channel mode. The protocol uses the non-cooperative game theory and an incomplete information power control algorithm to achieve multiple link concurrent transmission at the same channel. The Bayesian Nash equilibrium theorem is introduced to prove the existence and the uniqueness of the Nash equilibrium of the protocol' s non-cooperative game theory based power control algorithm. The simulation results show that the proposed protocol can perform well in the interference environment for concurrent data transmission. Significantly, it can improve the network throughput, reduce the data propagation delay , and save energy. Also, because of the effective use of the channel

  2. Beamforming in Ad Hoc Networks: MAC Design and Performance Modeling

    Directory of Open Access Journals (Sweden)

    Khalil Fakih

    2009-01-01

    Full Text Available We examine in this paper the benefits of beamforming techniques in ad hoc networks. We first devise a novel MAC paradigm for ad hoc networks when using these techniques in multipath fading environment. In such networks, the use of conventional directional antennas does not necessarily improve the system performance. On the other hand, the exploitation of the potential benefits of smart antenna systems and especially beamforming techniques needs a prior knowledge of the physical channel. Our proposition performs jointly channel estimation and radio resource sharing. We validate the fruitfulness of the proposed MAC and we evaluate the effects of the channel estimation on the network performance. We then present an accurate analytical model for the performance of IEEE 802.11 MAC protocol. We extend the latter model, by introducing the fading probability, to derive the saturation throughput for our proposed MAC when the simplest beamforming strategy is used in real multipath fading ad hoc networks. Finally, numerical results validate our proposition.

  3. Mac OS X Lion Server For Dummies

    CERN Document Server

    Rizzo, John

    2011-01-01

    The perfect guide to help administrators set up Apple's Mac OS X Lion Server With the overwhelming popularity of the iPhone and iPad, more Macs are appearing in corporate settings. The newest version of Mac Server is the ideal way to administer a Mac network. This friendly guide explains to both Windows and Mac administrators how to set up and configure the server, including services such as iCal Server, Podcast Producer, Wiki Server, Spotlight Server, iChat Server, File Sharing, Mail Services, and support for iPhone and iPad. It explains how to secure, administer, and troubleshoot the networ

  4. Take Control of Maintaining Your Mac

    CERN Document Server

    Kissell, Joe

    2009-01-01

    Keep your Mac running smoothly with our easy maintenance program! Regular maintenance is necessary to avoid problems and to ensure your Mac runs at peak performance, but it's hard to know what to do and when to do it. Best-selling author Joe Kissell has now applied his commonsense approach to the task of maintaining your Mac, whether you use Tiger or Leopard! Learn how to start on the right foot; what you should do daily, weekly, monthly, and yearly; and how to prepare for Mac OS X updates. Joe even explains how to monitor your Mac's health and debunks common panaceas. Read this book to lea

  5. Switching to a Mac For Dummies

    CERN Document Server

    Reinhold, Arnold

    2007-01-01

    Thinking of making the switch from your PC to a Mac? Congratulations! You're in for a great, virus-free ride. And Switching to Mac For Dummies makes it smoother than you ever imagined. From buying the Mac that's right for you to transferring your files to breaking your old Windows habits and learning to do things the (much easier) Mac way, it makes the whole process practically effortless. Whether you've been using Windows XP, Vista, or even Linux, you'll find simple, straightforward ways to make your transition go smoothly. That will leave you plenty of time to get familiar with Mac'

  6. Switching to the Mac The Missing Manual

    CERN Document Server

    Pogue, David

    2010-01-01

    Is Windows giving you pause? Ready to make the leap to the Mac instead? There has never been a better time to switch from Windows to Mac, and this incomparable guide will help you make a smooth transition. New York Times columnist and Missing Manuals creator David Pogue gets you past three challenges: transferring your stuff, assembling Mac programs so you can do what you did with Windows, and learning your way around Mac OS X. Learning to use a Mac is not a piece of cake, but once you do, the rewards are oh-so-much better. No viruses, worms, or spyware. No questionable firewalls, inefficien

  7. Magnetic activated cell sorting (MACS): utility in assisted reproduction.

    Science.gov (United States)

    Makker, Kartikeya; Agarwal, Ashok; Sharma, Rakesh K

    2008-07-01

    Assisted reproductive techniques (ART) have now been extensively incorporated in the management of infertile couples. But even after rapid methodological and technological advances the success rates of these procedures have been below expectations. This has led to development of many sperm preparation protocols to obtain an ideal semen sample for artificial reproduction. Sperm apoptosis has been heavily linked to failures in reproductive techniques. One of the earliest changes shown by apoptotic spermatozoa is externalization of phosphatidyl serine. Magnetic activated cell sorting (MACS) is a novel sperm preparation technique that separates apoptotic and non-apoptotic spermatozoa based on the expression of phosphatidylserine. This has led to the incorporation of MACS as a sperm preparation technique. The review highlights the principle and mechanism of this novel technique and enumerates its advantages as a sperm preparation technique. Its utility in ART as an efficient tool for sperm recovery and its application in cryopreservation of semen samples is also explained.

  8. Secure MAC for Wireless Sensor Networks through RBFNN

    Directory of Open Access Journals (Sweden)

    P.Sankara Rao

    2010-08-01

    Full Text Available This paper discusses an application of a neural network in wireless sensor network security. It presents a Radial Basic Function Neural Network based media access control protocol (MAC to secure a CSMA-based wireless sensor network against the denial-of-service attacks launched by adversaries. The Radial Basic Function Neural Network enhances the security of a WSN by constantly monitoring the parameters that exhibit unusual variations in case of an attack. The RBFN shuts down the MAC layer and the physical layer of the sensor node when the suspicion factor, the output of the MLP, exceeds a preset threshold level. The MLP-guarded secure WSN is implemented using the Prowler simulator. Simulation results show that the MLP helps in extending the lifetime of the WSN.

  9. 饱和情况下基于非竞争带宽请求机制的IEEE802.22MAC层协议性能分析%Performance Analysis of IEEE 802.22 MAC Protocol Based on Non- contention Bandwidth Request Mechanism under Saturated Condition

    Institute of Scientific and Technical Information of China (English)

    张元虎; 何晨; 蒋铃鸽

    2012-01-01

    In order to evaluate the performance of IEEE 802.22 MAC layer and study the influence of pro- tocol parameters, this paper proposed an analytical model using 3-dimention discrete-time Markov chain for IEEE 802.22 MAC layer based on non-contention bandwidth request (BR) mechanism under saturated condition. This model takes both sub-channel reservation mechanism and false alarm probability of spec- trum sensing into consideration, analyzes service event and arrival event at the frame node and derives the state transition probability matrix accurately. After Markov chain analysis, the formulas of throughput, forced termination probability and average delay of handoff queue were derived. The numerical results show that the model can be used to evaluate the protocol performance and analyze the trade-off of perform- ance metrics, and it can provide theoretical basis for choosing proper parameters.%为了分析IEEE802.22MAC(MediumAccessContr01)协议性能以及各协议参数对性能的影响,针对饱和情况下基于非竞争BR(BandwidthRequest)机制的IEEE802.22MAC协议提出了一种三维离散时间马尔科夫链分析模型.该模型同时考虑了协议的子信道预留机制和频谱感知的虚警概率,在帧节点处分析了离开事件以及到达事件,并在建模场景下准确得到了马尔科夫链的状态转移概率矩阵.通过马尔科夫链分析,得到了吞吐量、强迫中断率和切换队列的平均排队时延3种最主要性能指标的表达式.仿真结果表明:本文的分析模型可以准确评估协议性能,定量分析各项性能指标,为合理地选取协议参数提供理论依据.

  10. Mac OS X Tiger for Unix Geeks

    CERN Document Server

    Jepson, Brian

    2005-01-01

    If you're one of the many Unix developers drawn to Mac OS X for its Unix core, you'll find yourself in surprisingly unfamiliar territory. Unix and Mac OS X are kissing cousins, but there are enough pitfalls and minefields in going from one to another that even a Unix guru can stumble, and most guides to Mac OS X are written for Mac aficionados. For a Unix developer, approaching Tiger from the Mac side is a bit like learning Russian by reading the Russian side of a Russian-English dictionary. Fortunately, O'Reilly has been the Unix authority for over 25 years, and in Mac OS X Tiger for Unix Gee

  11. Teach yourself visually Mac Mini

    CERN Document Server

    Hart-Davis, Guy

    2012-01-01

    The perfect how-to guide for visual learners Apple?s Mac Mini packs a powerful punch is in a small package, including both HDMI and Thunderbolt ports plus the acclaimed OS X. But if you want to get the very most from all this power and versatility, be sure to get this practical visual guide. With full-color, step-by-step instructions as well as screenshots and illustrations on every page, it clearly shows you how to accomplish tasks rather than burying you in pages of text. Discover helpful visuals and how-tos on the OS, hardware specs, Launchpad, the App Store, multimedia capabilities (such

  12. Web Development with the Mac

    CERN Document Server

    Vegh, Aaron

    2010-01-01

    Learn Web development the Apple way and build a business. With a focus on both coding and creative development, this in-depth guide thoroughly covers what you need to know to build winning websites for clients — from what it takes to bring a business online to how to make your site interactive to how to run a freelance web business. In between, you'll master the technical tools of the trade — such as HTML, CSS, JavaScript, PHP, and Ruby on Rails — and learn how to create beautiful interfaces using Photoshop . This book covers everything a fledgling web developer working on a Mac needs to launc

  13. Analysis of 3gpp-MAC and two-key 3gpp-MAC

    DEFF Research Database (Denmark)

    Knudsen, Lars Ramkilde; Mitchell, C.J.

    2003-01-01

    Forgery and key-recovery attacks are described on the 3gpp-MAC scheme, proposed for inclusion in the 3gpp specification. Three main classes of attack are given, all of which operate whether or not truncation is applied to the MAC value. Attacks in the first class use a large number of 'chosen MACs......', those in the second class use a large number of 'known MACs', and those in the third class require a large number of MAC verifications, but very few known MACS and no chosen MACS. The first class yields both forgery and key-recovery attacks, whereas the second and third classes are key-recovery attacks...... only. Both single-key and two-key variants of 3gpp-MAC are considered; the forgery attacks are relevant to both variants, whereas the key-recovery attacks are only relevant to the two-key variant....

  14. Analysis of 3gpp-MAC and two-key 3gpp-MAC

    DEFF Research Database (Denmark)

    Knudsen, Lars Ramkilde; Mitchell, C.J.

    2003-01-01

    Forgery and key-recovery attacks are described on the 3gpp-MAC scheme, proposed for inclusion in the 3gpp specification. Three main classes of attack are given, all of which operate whether or not truncation is applied to the MAC value. Attacks in the first class use a large number of 'chosen MACs......', those in the second class use a large number of 'known MACs', and those in the third class require a large number of MAC verifications, but very few known MACS and no chosen MACS. The first class yields both forgery and key-recovery attacks, whereas the second and third classes are key-recovery attacks...... only. Both single-key and two-key variants of 3gpp-MAC are considered; the forgery attacks are relevant to both variants, whereas the key-recovery attacks are only relevant to the two-key variant....

  15. Take control of troubleshooting your Mac

    CERN Document Server

    Kissell, Joe

    2009-01-01

    Learn how to solve any Mac problem with Joe Kissell's expert advice! We may love our Macs, but they can still suffer significant problems. In this essential guide from best-selling author Joe Kissell, you'll learn 17 basic troubleshooting procedures and how to solve 9 common problems, along with an easy-to-follow way to troubleshoot novel problems. Whether your Mac won't turn on, experiences kernel panics repeatedly, or is glacially slow, this book has the calm, friendly advice you need to find a solution. Following in the footsteps of his critically acclaimed books Take Control of Mac OS X

  16. Teach yourself visually MacBook Pro

    CERN Document Server

    Hart-Davis, Guy

    2014-01-01

    Clear instructions to help visual learners get started with their MacBook Pro Covering all the essential information you need to get up to speed with your MacBook Pro, this new edition provides you with the most up-to-date information on performing everyday tasks quickly and easily. From basics such as powering on or shutting down the MacBook Pro to more advanced tasks such as running Windows applications, this visual guide provides the help and support you need to confidently use your MacBook Pro to its full potential.Empowers you to perform everyday tasks quickly and easilyCovers new hardwa

  17. Take control the Mac OS X lexicon

    CERN Document Server

    Zardetto, Sharon

    2009-01-01

    This ebook explains a little bit of everything; in fact, it's The Mac OS X (and then some) Lexicon because it's never just you and your Mac. It's you and your Mac and the Web, and your email, and that article you just read that threw 17 new acronyms at you or assumed that you knew all sorts of networking terms. Or it's you and your Mac and Finder features you've never touched, such as burn folders, smart folders, or proxy icons, and that mysterious Services submenu. This book is a great guide for Macintosh users everywhere who have trouble keeping up with the latest jargon, fo

  18. Macs all-in-one for dummies

    CERN Document Server

    Hutsko, Joe

    2014-01-01

    Your all-in-one guide to unleashing your Mac's full potential It's a Mac world out there. But if you haven't read the instruction manual, you may be neglecting some of your computer's coolest features. Turn to Macs All-in-One For Dummies' jam-packed guide to access the incredible tools within your computer. With this fully updated reference, you will learn how to use Launchpad and Mission Control; protect your Mac; back up and restore data with Time Machine; sync across devices in iCloud; import, organize, and share photos; direct in iMovie; compose in GarageBand; and so much more. The possi

  19. Quicksilver Power Mac G4

    CERN Multimedia

    2001-01-01

    A new generation with a reworked motherboard is launched on 2001 with however the same Graphite box. It also included a processor speed-bump, and brought the DVD-R "SuperDrive" to the mid-level model. The Quicksilver PowerMac was available in three configurations: The 733 MHz model, with 128 MB of RAM, a 40 GB hard drive, and a CD-RW drive, was 1,699 dollars, the 867 MHz configuration, with 128 MB of RAM, a 60 GB hard drive and a DVD-R drive, was 2,499 dollars, and the high-end dual-800 MHz model, with 256 MB of RAM, an 80 GB hard drive and a DVD-R drive, was 3,499 dollars. The 733 MHz model is the first personal computer to have a DVD burner, named SuperDrive at Apple. The design was updated on 2002 with 800 MHz, 933 MHz and dual 1 GHz configurations, becoming the first Mac to reach 1 GHz.

  20. Performance evaluation of IEEE 802.11 MAC layer in supporting delay sensitive services

    Directory of Open Access Journals (Sweden)

    Jyotsna Sengupta

    2010-02-01

    Full Text Available Providing QoS requirements like good throughput and minimum access delay are challenging tasks with regard to 802.11 WLAN protocols and Medium Access Control (MAC functions. IEEE 802.11 MAC layer supports two main protocols: DCF (Distributed Coordination Function and EDCF (Enhanced Distributed Coordination Function. During the evaluation of EDCF, the performance of various access categories was thedetermining factor. Two scenarios, with same Physical and MAC parameters, one implementing the DCF and other EDCF, were created in the network simulation tool (OPNET MODELER [5] to obtain the results. The results showed that the performance of EDCF was better in providing QoS for real-time interactive services (like video conferencing as compared to DCF, because of its ability to differentiate and prioritize various services. Whereas the DCF’s overall performance was marginally better for all kinds of services taken together.

  1. Wound healing in Mac-1 deficient mice.

    Science.gov (United States)

    Chen, Lin; Nagaraja, Sridevi; Zhou, Jian; Zhao, Yan; Fine, David; Mitrophanov, Alexander Y; Reifman, Jaques; DiPietro, Luisa A

    2017-05-01

    Mac-1 (CD11b/CD18) is a macrophage receptor that plays several critical roles in macrophage recruitment and activation. Because macrophages are essential for proper wound healing, the impact of Mac-1 deficiency on wound healing is of significant interest. Prior studies have shown that Mac-1(-/-) mice exhibit deficits in healing, including delayed wound closure in scalp and ear wounds. This study examined whether Mac-1 deficiency influences wound healing in small excisional and incisional skin wounds. Three millimeter diameter full thickness excisional wounds and incisional wounds were prepared on the dorsal skin of Mac-1 deficient (Mac-1(-/-) ) and wild type (WT) mice, and wound healing outcomes were examined. Mac-1 deficient mice exhibited a normal rate of wound closure, generally normal levels of total collagen, and nearly normal synthesis and distribution of collagens I and III. In incisional wounds, wound breaking strength was similar for Mac-1(-/-) and WT mice. Wounds of Mac-1 deficient mice displayed normal total macrophage content, although macrophage phenotype markers were skewed as compared to WT. Interestingly, amounts of TGF-β1 and its downstream signaling molecules, SMAD2 and SMAD3, were significantly decreased in the wounds of Mac-1 deficient mice compared to WT. The results suggest that Mac-1 deficiency has little impact on the healing of small excisional and incisional wounds. Moreover, the findings demonstrate that the effect of single genetic deficiencies on wound healing may markedly differ among wound models. These conclusions have implications for the interpretation of the many prior studies that utilize a single model system to examine wound healing outcomes in genetically deficient mice. © 2017 by the Wound Healing Society.

  2. A low power medium access control protocol for wireless medical sensor networks.

    Science.gov (United States)

    Lamprinos, I; Prentza, A; Sakka, E; Koutsouris, D

    2004-01-01

    The concept of a wireless integrated network of sensors, already applied in several sectors of our everyday life, such as security, transportation and environment monitoring, can as well provide an advanced monitor and control resource for healthcare services. By networking medical sensors wirelessly, attaching them in patient's body, we create the appropriate infrastructure for continuous and real-time monitoring of patient without discomforting him. This infrastructure can improve healthcare by providing the means for flexible acquisition of vital signs, while at the same time it provides more convenience to the patient. Given the type of wireless network, traditional medium access control (MAC) protocols cannot take advantage of the application specific requirements and information characteristics occurring in medical sensor networks, such as the demand for low power consumption and the rather limited and asymmetric data traffic. In this paper, we present the architecture of a low power MAC protocol, designated to support wireless networks of medical sensors. This protocol aims to improve energy efficiency by exploiting the inherent application features and requirements. It is oriented towards the avoidance of main energy wastage sources, such as idle listening, collision and power outspending.

  3. A MAC Mode for Lightweight Block Ciphers

    DEFF Research Database (Denmark)

    Luykx, Atul; Preneel, Bart; Tischhauser, Elmar Wolfgang;

    2016-01-01

    , but also allows high-performance parallel implementations. We highlight this in a comprehensive implementation study, instantiating LightMAC with PRESENT and the AES. Moreover, LightMAC allows flexible trade-offs between rate and maximum message length. Unlike PMAC and its many derivatives, Light...

  4. MAC-awake of sevoflurane in children.

    Science.gov (United States)

    Davidson, Andrew J; Wong, Aaron; Knottenbelt, Graham; Sheppard, Suzette; Donath, Susan; Frawley, Geoff

    2008-08-01

    Age influences the potency of anesthetic agents, but there is little information on how age influences MAC-awake. MAC-awake may be an important aspect of anesthesia potency for the prevention of awareness during anesthesia. The aim of this study was to measure MAC-awake in a range of ages in children. After institutional ethics approval and informed parental consent 60 children were enrolled; 20 in each of three age groups (2 to awake. The Dixon up-down method was used to determine progression of subsequent concentrations and MAC-awake (ED50) for the three age groups were obtained using the probit model. This study found evidence for a difference in ED50 between age groups (P = 0.008). The MAC-awake was highest in the youngest group (0.66%) and similar in the older groups (0.45% and 0.43%). Although MAC-awake changes with age, in the ages where awareness has been reported, MAC-awake was found to be relatively low, and therefore it seems unlikely that age-specific changes to MAC-awake are a cause for awareness in children aged 5-12 years.

  5. Nomogram to estimate age-related MAC.

    NARCIS (Netherlands)

    Lerou, J.G.C.

    2004-01-01

    BACKGROUND: In clinical practice it is difficult to estimate rapidly two important values: (i) the total age-corrected MAC multiple from measured end-expired concentrations of volatile agent and nitrous oxide; (ii) the end-expired concentration of volatile agent needed to obtain a given total MAC

  6. Mac OS X Snow Leopard for dummies

    CERN Document Server

    LeVitus, Bob

    2010-01-01

    Get to know Snow Leopard and make the most of your Mac Snow Leopard has a few new tricks up its sleeve, so whether you're new to Mac or a longtime Mac-thusiast, Mac expert Bob LeVitus has tips you'll appreciate. Learn how to start up your Mac, get to know the Dock and Finder, work your way through windows and dialogs, and organize and manage files and folders. Open the book and find: How to navigate around the Finder, Dock, and desktop Tips for opening, closing, resizing, and moving windows Steps for keeping Snow Leopard organized How to back up your system with Time Machine® Troubleshooting a

  7. MAC protocols for wireless sensor networks and their evaluation

    NARCIS (Netherlands)

    Halkes, G.P.

    2009-01-01

    The advent of small, and cheap sensors provides a wide range of measuring options. By making these sensors operate wirelessly we can now measure more than ever. However, wireless operation also provides new challenges. For example, how can we make these wireless sensors communicate effectively, i.e.

  8. MAC protocols for wireless sensor networks and their evaluation

    NARCIS (Netherlands)

    Halkes, G.P.

    2009-01-01

    The advent of small, and cheap sensors provides a wide range of measuring options. By making these sensors operate wirelessly we can now measure more than ever. However, wireless operation also provides new challenges. For example, how can we make these wireless sensors communicate effectively, i.e.

  9. LAMAN: Load Adaptable MAC for Ad Hoc Networks

    Directory of Open Access Journals (Sweden)

    Realp Marc

    2005-01-01

    Full Text Available In mobile ad hoc radio networks, mechanisms on how to access the radio channel are extremely important in order to improve network efficiency. In this paper, the load adaptable medium access control for ad hoc networks (LAMAN protocol is described. LAMAN is a novel decentralized multipacket MAC protocol designed following a cross-layer approach. Basically, this protocol is a hybrid CDMA-TDMA-based protocol that aims at throughput maximization in multipacket communication environments by efficiently combining contention and conflict-free protocol components. Such combination of components is used to adapt the nodes' access priority to changes on the traffic load while, at the same time, accounting for the multipacket reception (MPR capability of the receivers. A theoretical analysis of the system is developed presenting closed expressions of network throughput and packet delay. By simulations the validity of our analysis is shown and the performances of a LAMAN-based system and an Aloha-CDMA-based one are compared.

  10. Conception and FPGA implementation of IEEE 802.11s mesh network MAC layer transmitter

    CERN Document Server

    Chaari, Lamia; Kamoun, Lotfi

    2010-01-01

    This paper proposes, a hardware implementation of Wireless Mesh Networks (WMN) medium Access Controller (MAC) layer transmitter. In the literature a lot of works are focused on WMN routing protocol as well as performance analysis and software integration of WMN units, however few works deals with WMN hardware implementation. In this field our contribution is to conceive and to implements on FPGA a WMN MAC transmitter module. Our implementation, written in hardware description language (HDL) is based on the IEEE 802.11 s standard. The hardware implementation retains a good performance in speed.

  11. Mac OS X for Unix Geeks (Leopard)

    CERN Document Server

    Rothman, Ernest E; Rosen, Rich

    2009-01-01

    If you've been lured to Mac OS X because of its Unix roots, this invaluable book serves as a bridge between Apple's Darwin OS and the more traditional Unix systems. The new edition offers a complete tour of Mac OS X's Unix shell for Leopard and Tiger, and helps you find the facilities that replace or correspond to standard Unix utilities. Learn how to compile code, link to libraries, and port Unix software to Mac OS X and much more with this concise guide.

  12. Mac OS X Lion portable genius

    CERN Document Server

    Spivey, Dwight

    2012-01-01

    Two e-books, Mac OS X Lion Portable Genius and MacBook Pro Portable Genius, Third Edition, bundled in one package Books in the Portable Genius series provide readers with the most accessible, useful information possible, including plenty of tips and techniques for the most-used features in a product or software. These e-books will show you what you may not find out by just working with your MacBook Pro and OS X Lion. Genius icons present smart or innovative ways to do something, saving time and hassle. Easy-to-find information gives you the essentials plus insightful tips on how to navigate

  13. Office 2008 for Mac for dummies

    CERN Document Server

    LeVitus, Bob

    2013-01-01

    Office 2008 for Mac is here, with great new enhancements to all your favorite office productivity tools. Who better than "Dr. Mac, "Bob LeVitus, to show you how to load and use them all? From choosing the best version for your needs to managing your life with your online calendar, Office 2008 For Mac For Dummies covers what you need to know. It compares the Student/Teacher Edition, Standard Edition, and Professional Edition, then walks you through installing your preferred version and keeping it up to date. You'll find out all the things you can do with Word, Excel, PowerPoint, and Entourage,

  14. Beginning Mac OS X Snow Leopard programming

    CERN Document Server

    Trent, Michael

    2010-01-01

    Michael Trent is a technical reviewer for numerous books and magazine articles and the coauthor of Beginning Mac OS X Programming with Drew McCormack. Drew McCormack is an experienced computational scientist, founder of the ""The Mental Faculty""-an independent company developing software for the Mac and iPhone-and the coauthor of Beginning Mac OS X Programming with Michael Trent. Wrox Beginning guides are crafted to make learning programming languages and technologies easier than you think, providing a structured, tutorial format that will guide you through all the techniques involved.

  15. Learn Office 2011 for Mac OS X

    CERN Document Server

    Hart-Davis, Guy

    2011-01-01

    Office for Mac remains the leading productivity suite for Mac, with Apple's iWork and the free OpenOffice.org trailing far behind. And now it's being updated with a cleaner interface and more compatibility with Exchange and SharePoint. Learn Office 2011 for Mac OS X offers a practical, hands-on approach to using Office 2011 applications to create and edit documents and get work done efficiently. You'll learn how to customize Office, design, create, and share documents, manipulate data in a spreadsheet, and create lively presentations. You'll also discover how to organize your email, contacts,

  16. Energy efficient medium access protocol for wireless medical body area sensor networks.

    Science.gov (United States)

    Omeni, O; Wong, A; Burdett, A J; Toumazou, C

    2008-12-01

    This paper presents a novel energy-efficient MAC Protocol designed specifically for wireless body area sensor networks (WBASN) focused towards pervasive healthcare applications. Wireless body area networks consist of wireless sensor nodes attached to the human body to monitor vital signs such as body temperature, activity or heart-rate. The network adopts a master-slave architecture, where the body-worn slave node periodically sends sensor readings to a central master node. Unlike traditional peer-to-peer wireless sensor networks, the nodes in this biomedical WBASN are not deployed in an ad hoc fashion. Joining a network is centrally managed and all communications are single-hop. To reduce energy consumption, all the sensor nodes are in standby or sleep mode until the centrally assigned time slot. Once a node has joined a network, there is no possibility of collision within a cluster as all communication is initiated by the central node and is addressed uniquely to a slave node. To avoid collisions with nearby transmitters, a clear channel assessment algorithm based on standard listen-before-transmit (LBT) is used. To handle time slot overlaps, the novel concept of a wakeup fallback time is introduced. Using single-hop communication and centrally controlled sleep/wakeup times leads to significant energy reductions for this application compared to more ldquoflexiblerdquo network MAC protocols such as 802.11 or Zigbee. As duty cycle is reduced, the overall power consumption approaches the standby power. The protocol is implemented in hardware as part of the Sensiumtrade system-on-chip WBASN ASIC, in a 0.13- mum CMOS process.

  17. An integrated PHY-MAC analytical model for IEEE 802.15.7 VLC network with MPR capability

    Science.gov (United States)

    Yu, Hai-feng; Chi, Xue-fen; Liu, Jian

    2014-09-01

    Considering that the collision caused by hidden terminal is particularly serious due to the narrow beams of optical devices, the multi-packet reception (MPR) is introduced to mitigate the collisions for IEEE 802.15.7 visible light communication (VLC) system. To explore the impact of MPR on system performance and investigate the interaction between physical (PHY) layer and media access control (MAC) layer, a three dimensional (3D) integrated PHY-MAC analytical model of carrier sense multiple access/collision avoidance (CSMA/CA) is established based on Markov chain theory for VLC system, in which MPR is implemented through the use of orthogonal code sequence. Throughput is derived to evaluate the performance of VLC system with MPR capability under imperfect optical channel. The results can be used for the performance optimization of a VLC system with MPR capability.

  18. Learn Mac OS X Snow Leopard

    CERN Document Server

    Meyers, Scott

    2009-01-01

    You're smart and savvy, but also busy. This comprehensive guide to Apple's Mac OS X 10.6, Snow Leopard, gives you everything you need to know to live a happy, productive Mac life. Learn Mac OS X Snow Leopard will have you up and connected lickity split. With a minimum of overhead and a maximum of useful information, you'll cover a lot of ground in the time it takes other books to get you plugged in. If this isn't your first experience with Mac OS X, skip right to the "What's New in Snow Leopard" sections. You may also find yourself using this book as a quick refresher course or a way

  19. Macintosh Troubleshooting Pocket Guide for Mac OS

    CERN Document Server

    Lerner, David; Corporation, Tekserve

    2009-01-01

    The Macintosh Troubleshooting Pocket Guide covers the most common user hardware and software trouble. It's not just a book for Mac OS X (although it includes tips for OS X and Jaguar), it's for anyone who owns a Mac of any type-- there are software tips going back as far as OS 6. This slim guide distills the answers to the urgent questions that Tekserve's employee's answer every week into a handy guide that fits in your back pocket or alongside your keyboard.

  20. Enhanced Sleep Mode MAC Control for EPON

    DEFF Research Database (Denmark)

    Yan, Ying; Dittmann, Lars

    2011-01-01

    This paper introduces sleep mode operations for EPON. New MAC control functions are proposed to schedule sleep periods. Traffic profiles are considered to optimize energy efficiency and network performances. Simulation results are analyzed in OPNET modeler.......This paper introduces sleep mode operations for EPON. New MAC control functions are proposed to schedule sleep periods. Traffic profiles are considered to optimize energy efficiency and network performances. Simulation results are analyzed in OPNET modeler....

  1. 42 CFR 405.1120 - Filing briefs with the MAC.

    Science.gov (United States)

    2010-10-01

    ... 42 Public Health 2 2010-10-01 2010-10-01 false Filing briefs with the MAC. 405.1120 Section 405....1120 Filing briefs with the MAC. Upon request, the MAC will give the party requesting review, as well... ending with the date the brief is received by the MAC will not be counted toward the adjudication...

  2. 42 CFR 423.1974 - Medicare Appeals Council (MAC) review.

    Science.gov (United States)

    2010-10-01

    ... 42 Public Health 3 2010-10-01 2010-10-01 false Medicare Appeals Council (MAC) review. 423.1974..., MAC review, and Judicial Review § 423.1974 Medicare Appeals Council (MAC) review. An enrollee who is dissatisfied with an ALJ hearing decision may request that the MAC review the ALJ's decision or dismissal as...

  3. 42 CFR 423.2130 - Effect of the MAC's decision.

    Science.gov (United States)

    2010-10-01

    ... 42 Public Health 3 2010-10-01 2010-10-01 false Effect of the MAC's decision. 423.2130 Section 423... (CONTINUED) MEDICARE PROGRAM VOLUNTARY MEDICARE PRESCRIPTION DRUG BENEFIT Reopening, ALJ Hearings, MAC review, and Judicial Review § 423.2130 Effect of the MAC's decision. The MAC's decision is final and binding...

  4. 42 CFR 405.1130 - Effect of the MAC's decision.

    Science.gov (United States)

    2010-10-01

    ... 42 Public Health 2 2010-10-01 2010-10-01 false Effect of the MAC's decision. 405.1130 Section 405....1130 Effect of the MAC's decision. The MAC's decision is final and binding on all parties unless a Federal district court issues a decision modifying the MAC's decision or the decision is revised as the...

  5. 42 CFR 423.2118 - Obtaining evidence from the MAC.

    Science.gov (United States)

    2010-10-01

    ... 42 Public Health 3 2010-10-01 2010-10-01 false Obtaining evidence from the MAC. 423.2118 Section..., MAC review, and Judicial Review § 423.2118 Obtaining evidence from the MAC. An enrollee may request... the costs of providing these items. If an enrollee requests evidence from the MAC and an opportunity...

  6. 42 CFR 423.2126 - Case remanded by the MAC.

    Science.gov (United States)

    2010-10-01

    ... 42 Public Health 3 2010-10-01 2010-10-01 false Case remanded by the MAC. 423.2126 Section 423.2126... (CONTINUED) MEDICARE PROGRAM VOLUNTARY MEDICARE PRESCRIPTION DRUG BENEFIT Reopening, ALJ Hearings, MAC review, and Judicial Review § 423.2126 Case remanded by the MAC. (a) When the MAC may remand a case to the ALJ...

  7. 42 CFR 423.2120 - Filing briefs with the MAC.

    Science.gov (United States)

    2010-10-01

    ... 42 Public Health 3 2010-10-01 2010-10-01 false Filing briefs with the MAC. 423.2120 Section 423... (CONTINUED) MEDICARE PROGRAM VOLUNTARY MEDICARE PRESCRIPTION DRUG BENEFIT Reopening, ALJ Hearings, MAC review, and Judicial Review § 423.2120 Filing briefs with the MAC. Upon request, the MAC will give the...

  8. Joint MIMO-OFDM and MAC Design for Broadband Multihop Ad Hoc Networks

    Directory of Open Access Journals (Sweden)

    Wang Dandan

    2006-01-01

    Full Text Available Multiple-input multiple-output (MIMO and orthogonal frequency division multiplexing (OFDM are very promising techniques to exploit spatial diversity and frequency diversity in the physical layer of broadband wireless communications. However, the application of these techniques to broadband multihop ad hoc networks is subject to inefficiencies since existing medium access control (MAC schemes are designed to allow only one node to transmit in a neighborhood. Therefore, adding more relays to increase the transmission range decreases the throughput. With MIMO-OFDM, multiple transmissions can coexist in the same neighborhood. A new transceiver architecture with MIMO-OFDM and MAC scheme is proposed in this paper. The new MAC scheme multiple-antennas receiver-initiated busy-tone medium access (MARI-BTMA is based on receiver-initiated busy-tone medium access (RI-BTMA and uses multiple out of band busy tones to avoid the collision of nodes on the same channel. With the proposed MAC scheme, multiple users can transmit simultaneously in the same neighborhood. Although basic MARI-BTMA shows good performance at high traffic load, to improve the performance at low traffic loads, 1-persistent MARI-BTMA is proposed so that users can choose different MAC scheme according to the statistical traffic load in the system. In this paper, both theoretical and numerical analysis of the throughput and delay are presented. Analysis and simulation results show the improved performance of MARI-BTMA compared with RI-BTMA and carrier sensing medium access/collision avoidance (CSMA/CA.

  9. On Proper Selection of Multihop Relays for Future Enhancement of AeroMACS Networks

    Science.gov (United States)

    Kamali, Behnam; Kerczewski, Robert J.; Apaza, Rafael D.

    2015-01-01

    As the Aeronautical Mobile Airport Communications System (AeroMACS) has evolved from a technology concept to a deployed communications network over major US airports, it is now time to contemplate whether the existing capacity of AeroMACS is sufficient to meet the demands set forth by all fixed and mobile applications over the airport surface given the AeroMACS constraints regarding bandwidth and transmit power. The underlying idea in this article is to present IEEE 802.16j-based WiMAX as a technology that can address future capacity enhancements and therefore is most feasible for AeroMACS applications. The principal argument in favor IEEE 802.16j technology is the flexible and cost effective extension of radio coverage that is afforded by relay fortified networks, with virtually no increase in the power requirements and virtually no rise in interference levels to co-allocated applications. The IEEE 802.16j-based multihop relay systems are briefly described. The focus is on key features of this technology, frame structure, and its architecture. Next, AeroMACS is described as a WiMAX-based wireless network. The two major relay modes supported by IEEE 802.16j amendment, i.e., transparent and non-transparent are described. The benefits of employing multihop relays are listed. Some key challenges related to incorporating relays into AeroMACS networks are discussed. The selection of relay type in a broadband wireless network affects a number of network parameters such as latency, signal overhead, PHY (Scalable Physical Layer) and MAC (Media Access Layer) layer protocols, consequently it can alter key network quantities of throughput and QoS (Quality of Service).

  10. Mac OS X Snow Leopard试用

    Institute of Scientific and Technical Information of China (English)

    大大

    2009-01-01

    苹果新一代操作系统Mac OS X 10.6 Snow Leopard(雪豹)于8月底上市。根据NPD集团的统计数据,该系统在美国市场前两周的销售非常喜人,是2007年Mac OS X 10.5 Leopard上市销量的2倍以上,是2005年的Mac OS X 10.4 Tiger操作系统的售量的4倍。假如你也对升级价格仅需88元雪豹系统感兴趣,就让我们从一起升级安装开始,体验它独特的魅力。

  11. MacBook Pro Portable Genius

    CERN Document Server

    Miser, Brad

    2011-01-01

    Tips and techniques for forward-thinking MacBook Pro users Now that you have a MacBook Pro, you need just one more accessory, your very own copy of MacBook Pro Portable Genius, Third Edition. This handy, compact book lets you in on a wealth of tips and tricks, so you get the very most out of Apple's very popular notebook. Discover the latest on the most recent release of iLife, get the skinny on the new Intel Core i7 and i5 processors in the Pro, see how to go wireless in a smart way, and much more. The book is easy to navigate, doesn't skimp on the essentials, and helps you save time and avoi

  12. MacSelfService online tutorial

    CERN Document Server

    CERN. Geneva

    2016-01-01

    Mac Self-Service is a functionality within the Mac Desktop Service built and maintained to empower CERN users by giving them easy access to applications and configurations through the Self-Service application. This tutorial (text attached to the event page) explains how to install Mac Self-Service and how to use it to install applications and printers. Content owner: Vincent Nicolas Bippus Presenter: Pedro Augusto de Freitas Batista Tell us what you think via e-learning.support at cern.ch More tutorials in the e-learning collection of the CERN Document Server (CDS) https://cds.cern.ch/collection/E-learning%20modules?ln=en All info about the CERN rapid e-learning project is linked from http://twiki.cern.ch/ELearning  

  13. Mac OS X Snow Leopard pocket guide

    CERN Document Server

    Seiblod, Chris

    2009-01-01

    Whether you're new to the Mac or a longtime user, this handy book is the quickest way to get up to speed on Snow Leopard. Packed with concise information in an easy-to-read format, Mac OS X Snow Leopard Pocket Guide covers what you need to know and is an ideal resource for problem-solving on the fly. This book goes right to the heart of Snow Leopard, with details on system preferences, built-in applications, and utilities. You'll also find configuration tips, keyboard shortcuts, guides for troubleshooting, lots of step-by-step instructions, and more. Learn about new features and changes s

  14. MacBook Pro Portable Genius

    CERN Document Server

    Miser, Brad

    2012-01-01

    Discover loads of tips and techniques for the newest MacBook Pro You're already ahead of the game with a MacBook Pro. Now you can get even more out the popular Apple notebook with the new edition of this handy, compact book. Crammed with savvy insights and tips on key tools and shortcuts, this book will help you increase your productivity and keep your Apple digital lifestyle on track. From desktop sharing and wireless networking to running Windows applications, this book avoids fluff, doesn't skimp on the essentials, saves you time and hassle, and shows you what you most want to know. Include

  15. ATLAS: A Traffic Load Aware Sensor MAC Design for Collaborative Body Area Sensor Networks

    OpenAIRE

    Young-Cheol Bang; Md. Obaidur Rahman; Sungwon Lee; Choong Seon Hong

    2011-01-01

    In collaborative body sensor networks, namely wireless body area networks (WBANs), each of the physical sensor applications is used to collaboratively monitor the health status of the human body. The applications of WBANs comprise diverse and dynamic traffic loads such as very low-rate periodic monitoring (i.e., observation) data and high-rate traffic including event-triggered bursts. Therefore, in designing a medium access control (MAC) protocol for WBANs, energy conservation should be the p...

  16. A reliable, delay bounded and less complex communication protocol for multicluster FANETs

    Directory of Open Access Journals (Sweden)

    Wajiya Zafar

    2017-02-01

    Full Text Available Recently, Flying Ad-hoc Networks (FANETs, enabling ad-hoc networking between Unmanned Aerial Vehicles (UAVs is gaining importance in several military and civilian applications. The sensitivity of the applications requires adaptive; efficient; delay bounded and scalable communication network among UAVs for data transmission. Due to communication protocol complexity; rigidity; cost of commercial-off-the-shelf (COT components; limited radio bandwidth; high mobility and computational resources; maintaining the desired level of Quality of Service (QoS becomes a daunting task. For the first time in this research we propose multicluster FANETs for efficient network management; the proposed scheme considerably reduces communication cost and optimizes network performance as well as exploit low power; less complex and low cost IEEE 802.15.4 (MAC protocol for intercluster and intracluster communication. In this research both beacon enabled mode and beaconless modes have been investigated with Guaranteed Time Slots (GTS and virtual Time Division Multiple Access (TDMA respectively. The methodology plays a key role towards reserving bandwidth for latency critical applications; eliminate collisions and medium access delays. Moreover analysis ad-hoc routing protocols including two proactive (OLSR, DSDV and one reactive (AODV is also presented. The results shows that the proposed scheme guarantees high packet delivery ratios while maintaining acceptable levels of latency requirements comparable with more complex and dedicatedly designed protocols in literature.

  17. Collisions of Rydberg Atoms with Charged Particles

    Science.gov (United States)

    MacAdam, Keith B.

    2000-10-01

    The long range of Coulomb interactions, together with the large size, long radiative lifetimes and high state densities of highly excited Rydberg atoms, results in inelastic collision cross sections of prodigious size -- often large enough to outweigh small number densities in astrophysica and cool laboratory plasmas -- and in other unusual features. This talk will provide: (a) a brief survey of the significant features of collisions between electron or positive ions and state-selected Rydberg atoms and of recent experiments( O. Makarov and K.B. MacAdam, Phys. Rev. A 60), 2131-8 (1999); and K.B. MacAdam, J.C. Day and D.M. Homan, Comm. At. Mol. Phys./Comm. Mod. Phys. 1(2), Part D, 57-73 (1999). to investigate them; (b) an introduction to some of the special techniques that have been developed(J.L. Horn, D.M. Homan, C.S. Hwang, W.L. Fuqua III and K.B. MacAdam, Rev. Sci. Instrum. 69), 4086-93 (1998). for preparation, manipulation and detection of Rydberg atoms; and (c) a glimpse at new directions in Rydberg atom collision research.

  18. A Hybrid Sender- and Receiver-Initiated Protocol Scheme in Underwater Acoustic Sensor Networks.

    Science.gov (United States)

    Lee, Jae-Won; Cho, Ho-Shin

    2015-01-01

    In this paper, we propose a method for sharing the handshakes of control packets among multiple nodes, which we call a hybrid sender- and receiver-initiated (HSR) protocol scheme. Handshake-sharing can be achieved by inviting neighbors to join the current handshake and by allowing them to send their data packets without requiring extra handshakes. Thus, HSR can reduce the signaling overhead involved in control packet exchanges during handshakes, as well as resolve the spatial unfairness problem between nodes. From an operational perspective, HSR resembles the well-known handshake-sharing scheme referred to as the medium access control (MAC) protocol using reverse opportunistic packet appending (ROPA). However, in ROPA the waiting time is not controllable for the receiver's neighbors and thus unexpected collisions may occur at the receiver due to hidden neighbors, whereas the proposed scheme allows all nodes to avoid hidden-node-induced collisions according to an elaborately calculated waiting time. Our computer simulations demonstrated that HSR outperforms ROPA with respect to both the throughput and delay by around 9.65% and 11.36%, respectively.

  19. A Hybrid Sender- and Receiver-Initiated Protocol Scheme in Underwater Acoustic Sensor Networks

    Directory of Open Access Journals (Sweden)

    Jae-Won Lee

    2015-11-01

    Full Text Available In this paper, we propose a method for sharing the handshakes of control packets among multiple nodes, which we call a hybrid sender- and receiver-initiated (HSR protocol scheme. Handshake-sharing can be achieved by inviting neighbors to join the current handshake and by allowing them to send their data packets without requiring extra handshakes. Thus, HSR can reduce the signaling overhead involved in control packet exchanges during handshakes, as well as resolve the spatial unfairness problem between nodes. From an operational perspective, HSR resembles the well-known handshake-sharing scheme referred to as the medium access control (MAC protocol using reverse opportunistic packet appending (ROPA. However, in ROPA the waiting time is not controllable for the receiver’s neighbors and thus unexpected collisions may occur at the receiver due to hidden neighbors, whereas the proposed scheme allows all nodes to avoid hidden-node-induced collisions according to an elaborately calculated waiting time. Our computer simulations demonstrated that HSR outperforms ROPA with respect to both the throughput and delay by around 9.65% and 11.36%, respectively.

  20. Results from the MAC Vertex chamber

    Energy Technology Data Exchange (ETDEWEB)

    Nelson, H.N.

    1987-05-01

    The design, construction, and performance characteristics of a high precision gaseous drift chamber made of thin walled proportional tubes are described. The device achieved an average spatial resolution of 45 ..mu..m in use for physics analysis with the MAC detector. The B-lifetime result obtained with this chamber is discussed.

  1. MacIntyre, Managerialism and Universities

    Science.gov (United States)

    Stolz, Steven A.

    2017-01-01

    MacIntyre's earlier work and concern with social science enquiry not only exposes its limits, but also provides an insight into how its knowledge claims have been put to ideological use. He maintains that the institutional embodiment of these ideological ideas is the bureaucratic manager who has had a negative role to play in social structures…

  2. Exposure histories of lunar meteorites: ALHA81005, MAC88104, MAC88105, and Y791197

    Energy Technology Data Exchange (ETDEWEB)

    Nishiizumi, K.; Arnold, J.R. (Univ. of California, San Diego, (United States)); Klein, J.; Fink, D.; Middleton, R. (Univ. of Pennsylvania, Philadelphia (United States)); Kubik, P.W.; Sharma, P.; Elmore, D. (Univ. of Rochester, NY (United States)); Reedy, R.C. (Los Alamos National Lab., NM (United States))

    1991-11-01

    The cosmogenic radionuclides {sup 41}Ca, {sup 36}Cl, {sup 26}Al, and {sup 10}Be in the Allan Hills 81005, MacAlpine Hills 88104, MacAlpine Hills 88105,and Yamato 791197 meteorites were measured by accelerator mass spectrometry (AMS). {sup 53}Mn in Allan Hills 81005 and Yamato 791197 was measured by activation. These four lunar meteorites experienced similar histories. They were ejected from near the surface of the Moon ranging in depth down to 400 g/cm{sup 2} and had very short transition times (less than 0.1 Ma) from the Moon to the Earth. A comparison of the cosmogenic nuclide concentrations in MacAlpine Hills 88104 and MacAlpine Hills 88105 clearly indicates that they are a pair from the same fall.

  3. 42 CFR 405.1126 - Case remanded by the MAC.

    Science.gov (United States)

    2010-10-01

    ... 42 Public Health 2 2010-10-01 2010-10-01 false Case remanded by the MAC. 405.1126 Section 405.1126....1126 Case remanded by the MAC. (a) When the MAC may remand a case. Except as specified in § 405.1122(c), the MAC may remand a case in which additional evidence is needed or additional action by the ALJ is...

  4. Reduction in standard MAC and MAC for intubation after clonidine premedication in children.

    Science.gov (United States)

    Inomata, S; Kihara, S; Yaguchi, Y; Baba, Y; Kohda, Y; Toyooka, H

    2000-11-01

    We examined the relative effects of different doses of oral clonidine on the MAC for endotracheal intubation (MACEI) and the MAC for skin incision (MAC) in children. We studied 90 children (15 in each group) (age range 2-8 yr, weight 10-27 kg, height 89-124 cm) who received one of three preanaesthetic medications: placebo (control), oral clonidine 2 micrograms kg-1, or oral clonidine 4 micrograms kg-1 100 min before anaesthesia. Anaesthesia was induced and maintained with sevoflurane in oxygen and air without i.v. anesthetics and neuromuscular relaxants. The end-tidal sevoflurane concentration was kept constant for > or = 15 min before tracheal intubation or skin incision. MACs were determined using Dixon's 'up-and-down method'. Mean (SD) MACEIs of sevoflurane were 2.9 (0.1)%, 2.5 (0.1)% and 1.9 (0.1)% (P clonidine 2 micrograms kg-1 and clonidine 4 micrograms kg-1 groups. The MACEIs and MACs decreased dose-dependently. The MACEI/MAC ratio (1.4) was not affected by clonidine.

  5. 42 CFR 423.2128 - Action of the MAC.

    Science.gov (United States)

    2010-10-01

    ... 42 Public Health 3 2010-10-01 2010-10-01 false Action of the MAC. 423.2128 Section 423.2128 Public...) MEDICARE PROGRAM VOLUNTARY MEDICARE PRESCRIPTION DRUG BENEFIT Reopening, ALJ Hearings, MAC review, and Judicial Review § 423.2128 Action of the MAC. (a) After it has reviewed all the evidence in the...

  6. 42 CFR 405.1118 - Obtaining evidence from the MAC.

    Science.gov (United States)

    2010-10-01

    ... 42 Public Health 2 2010-10-01 2010-10-01 false Obtaining evidence from the MAC. 405.1118 Section... Council Review § 405.1118 Obtaining evidence from the MAC. A party may request and receive a copy of all... these items. If a party requests evidence from the MAC and an opportunity to comment on that evidence...

  7. 42 CFR 405.1128 - Action of the MAC.

    Science.gov (United States)

    2010-10-01

    ... 42 Public Health 2 2010-10-01 2010-10-01 false Action of the MAC. 405.1128 Section 405.1128 Public... the MAC. (a) After it has reviewed all the evidence in the administrative record and any additional evidence received, subject to the limitations on MAC consideration of additional evidence in § 405.1122...

  8. 42 CFR 422.608 - Medicare Appeals Council (MAC) review.

    Science.gov (United States)

    2010-10-01

    ... 42 Public Health 3 2010-10-01 2010-10-01 false Medicare Appeals Council (MAC) review. 422.608... and Appeals § 422.608 Medicare Appeals Council (MAC) review. Any party to the hearing, including the MA organization, who is dissatisfied with the ALJ hearing decision, may request that the MAC review...

  9. MAC 700 Wash高亮度灯具

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    马田最新推出的MAC 700 Wash高亮度灯具继承了MAC系列的传统优点.具有与MAC 700 Profile相同的强大功能、模组桔构和出色设计,是MAC 700 Profile的“最佳搭档”。

  10. Collision Mechanics

    DEFF Research Database (Denmark)

    Pedersen, Preben Terndrup; Servis, D.P.; Zhang, Shengming;

    1999-01-01

    The first section of the present report describes the procedures that are being programmed at DTU for evaluation of the external collision dynamics. Then follows a detailed description of a comprehensive finite element analysis of one collision scenario for MS Dextra carried out at NTUA. The last...

  11. Isolation and characterisation of human gingival margin-derived STRO-1/MACS1 and MACS2 cell populations

    Institute of Scientific and Technical Information of China (English)

    Karim M Fawzy El-Sayed; Sebastian Paris; Christian Graetz; Neemat Kassem; Mohamed Mekhemar; Hendrick Ungefroren; Fred Fandrich; Christof Dorfer

    2015-01-01

    Recently, gingival margin-derived stem/progenitor cells isolated via STRO-1/magnetic activated cell sorting (MACS) showed remarkable periodontal regenerative potential in vivo. As a second-stage investigation, the present study’s aim was to perform in vitro characterisation and comparison of the stem/progenitor cell characteristics of sorted STRO-1-positive (MACS1) and STRO-1-negative (MACS2) cell populations from the human free gingival margin. Cells were isolated from the free gingiva using a minimally invasive technique and were magnetically sorted using anti-STRO-1 antibodies. Subsequently, the MACS1 and MACS2 cell fractions were characterized by flow cytometry for expression of CD14, CD34, CD45, CD73, CD90, CD105, CD146/MUC18 and STRO-1. Colony-forming unit (CFU) and multilineage differentiation potential were assayed for both cell fractions. Mineralisation marker expression was examined using real-time polymerase chain reaction (PCR). MACS1 and MACS2 cell fractions showed plastic adherence. MACS1 cells, in contrast to MACS2 cells, showed all of the predefined mesenchymal stem/progenitor cell characteristics and a significantly higher number of CFUs (P,0.01). More than 95%of MACS1 cells expressed CD105, CD90 and CD73;lacked the haematopoietic markers CD45, CD34 and CD14, and expressed STRO-1 and CD146/MUC18. MACS2 cells showed a different surface marker expression profile, with almost no expression of CD14 or STRO-1, and more than 95%of these cells expressed CD73, CD90 and CD146/MUC18, as well as the haematopoietic markers CD34 and CD45 and CD105. MACS1 cells could be differentiated along osteoblastic, adipocytic and chondroblastic lineages. In contrast, MACS2 cells demonstrated slight osteogenic potential. Unstimulated MACS1 cells showed significantly higher expression of collagen I (P,0.05) and collagen III (P,0.01), whereas MACS2 cells demonstrated higher expression of osteonectin (P,0.05;Mann–Whitney). The present study is the first to compare gingival

  12. MacBook All-in-One For Dummies

    CERN Document Server

    Chambers, Mark L

    2011-01-01

    Get comfortable and confident with your MacBook! Combining the fun-but-straightforward content of nine minibooks, this new edition of MacBook All-in-One For Dummies delivers helpful coverage of the rich features and essential tools you need to know to use the MacBook to its fullest potential. You'll learn an array of MacBook basics while veteran author Mark Chambers walks you through setting up your MacBook, running programs, finding files with Finder, searching with Spotlight, keeping track with Address Book, enjoying music with iTunes, creating cool multimedia projects with iLife, and more.

  13. A Distributed Mechanism for Handling of Adaptive/Intelligent Selfish Misbehaviour at MAC Layer in Mobile Ad Hoc Networks

    Institute of Scientific and Technical Information of China (English)

    Raja Gunasekaran; Vaidheyanathan Rhymend Uthariaraj; Uamapathy Yamini; Rajagopalan Sudharsan; Selvaraj Sujitha Priyadarshini

    2009-01-01

    Medium access control (MAC) protocols such as IEEE 802.11 are used in wireless networks for sharing of the wireless medium.. The random nature of the protocol operation together with the inherent difficulty of monitoring in the open poses significant challenges. All nodes are expected to comply with the protocol rules. But, some nodes in order to gain greater benefits misbehave by not complying with the rules. One such selfish misbehavior is waiting for smaller back-off intervals when compared to the other nodes in the same subnet. Such selfish misbehavior is being tackled in this paper. A diagnosis scheme and a penalty scheme are being proposed for overcoming such selfish-misbehavior at MAC layer of mobile ad hoc networks which could be extended to other types of networks also.

  14. Seán MacDiarmada

    Directory of Open Access Journals (Sweden)

    Madden

    2016-12-01

    Full Text Available Seán MacDiarmada: Signatory to Proclamation – Executed after the Rising of 1916 - Leitrim to Kilmainham was written by Tom Madden to coincide with the 1916/2016 centenary commemorations. The play was first performed at the Mullagh Arts Festival in Cavan during September 2016 and provides a lively account of the background and activism of one the seven leaders of the Easter Rising of 1916. The action plays out over twelve scenes taking in MacDiarmada's journey from teacher to revolutionary activist culminating in a deeply flawed court-martial and his subsequent execution by a British Army firing squad on May 12th, 1916.

  15. Earth tides in MacDonald's model

    CERN Document Server

    Ferraz-Mello, S

    2013-01-01

    We expand the equations used in MacDonald's 1964 theory and Fourier analyze the tidal variations of the height at one point on the Earth surface, and also the tidal potential at such point. It is shown that no intrinsic law is relating the lag of the tide components to their frequencies. In other words, no simple rheology is being intrinsically fixed by MacDonald's equations. The same is true of the modification proposed by Singer(1968). At variance with these two cases, the modification proposed by Williams and Efroimsky (2012) fix the standard Darwin rheology in which the lags are proportional to the frequencies and their model is, in this sense, equivalent to Mignard's 1979 formulation of Darwin's theory.

  16. MacBook Pro portable genius

    CERN Document Server

    Gruman, Galen

    2013-01-01

    Learn the skills, tools and shortcuts you need in order to make the most of your MacBook Pro This easy-to-use, compact guide skips the fluff and gets right to the essentials so that you can maximize all the latest features of the MacBook Pro. Packed with savvy insights and tips on key tools and shortcuts, this handy book aims to help you increase your productivity and save you time and hassle. From desktop sharing and wireless networking to running Windows applications and more, this book shows you what you want to know. Includes the latest version of OS X, iCloud, FaceTime, and moreCovers al

  17. ATLAS: A Traffic Load Aware Sensor MAC Design for Collaborative Body Area Sensor Networks

    Directory of Open Access Journals (Sweden)

    Young-Cheol Bang

    2011-12-01

    Full Text Available In collaborative body sensor networks, namely wireless body area networks(WBANs, each of the physical sensor applications is used to collaboratively monitor thehealth status of the human body. The applications of WBANs comprise diverse and dynamictraffic loads such as very low-rate periodic monitoring (i.e., observation data and high-ratetraffic including event-triggered bursts. Therefore, in designing a medium access control(MAC protocol for WBANs, energy conservation should be the primary concern duringlow-traffic periods, whereas a balance between satisfying high-throughput demand andefficient energy usage is necessary during high-traffic times. In this paper, we design atraffic load-aware innovative MAC solution for WBANs, called ATLAS. The design exploitsthe superframe structure of the IEEE 802.15.4 standard, and it adaptively uses the contentionaccess period (CAP, contention free period (CFP and inactive period (IP of the superframebased on estimated traffic load, by applying a dynamic “wh” (whenever which is requiredapproach. Unlike earlier work, the proposed MAC design includes load estimation fornetwork load-status awareness and a multi-hop communication pattern in order to preventenergy loss associated with long range transmission. Finally, ATLAS is evaluated throughextensive simulations in ns-2 and the results demonstrate the effectiveness of the protocol.

  18. ATLAS: a traffic load aware sensor MAC design for collaborative body area sensor networks.

    Science.gov (United States)

    Rahman, Md Obaidur; Hong, Choong Seon; Lee, Sungwon; Bang, Young-Cheol

    2011-01-01

    In collaborative body sensor networks, namely wireless body area networks (WBANs), each of the physical sensor applications is used to collaboratively monitor the health status of the human body. The applications of WBANs comprise diverse and dynamic traffic loads such as very low-rate periodic monitoring (i.e., observation) data and high-rate traffic including event-triggered bursts. Therefore, in designing a medium access control (MAC) protocol for WBANs, energy conservation should be the primary concern during low-traffic periods, whereas a balance between satisfying high-throughput demand and efficient energy usage is necessary during high-traffic times. In this paper, we design a traffic load-aware innovative MAC solution for WBANs, called ATLAS. The design exploits the superframe structure of the IEEE 802.15.4 standard, and it adaptively uses the contention access period (CAP), contention free period (CFP) and inactive period (IP) of the superframe based on estimated traffic load, by applying a dynamic "wh" (whenever which is required) approach. Unlike earlier work, the proposed MAC design includes load estimation for network load-status awareness and a multi-hop communication pattern in order to prevent energy loss associated with long range transmission. Finally, ATLAS is evaluated through extensive simulations in ns-2 and the results demonstrate the effectiveness of the protocol.

  19. 关于Mac OS X Lion

    Institute of Scientific and Technical Information of China (English)

    饭桶

    2011-01-01

    Lion是Mac OS X操作系统的第七个版本,第一个版本是2001年发布的Cheetah(猎豹).或许很多Windows用户会认为,Lion不过是一次升级,主版本仍然是Mac OSX.那么我不介意稍微解释一下:Mac OS X对应的层次是Windows,Cheetah或者Lion相当于XP,或者7.因此即使从软件工程的角度看,Lion也是一个全新的操作系统.由于重新编译了核心,Lion的安装文件只有3.6GB大小,比上一代(Snow Leopard)减少了近一半的体积,这种比旧版本体积更小的新操作系统在历史上可不多见.

  20. Frontier Fields Clusters: Deep Chandra Observations of the Complex Merger MACS J1149.6+2223

    CERN Document Server

    Ogrean, G A; Jones, C; Forman, W; Dawson, W A; Golovich, N; Andrade-Santos, F; Murray, S S; Nulsen, P; Roediger, E; Zitrin, A; Bulbul, E; Kraft, R; Goulding, A; Umetsu, K; Mroczkowski, T; Bonafede, A; Randall, S; Sayers, J; Churazov, E; David, L; Merten, J; Donahue, M; Mason, B; Rosati, P; Vikhlinin, A; Ebeling, H

    2016-01-01

    The HST Frontier Fields cluster MACS J1149.6+2223 is one of the most complex merging clusters, believed to consist of four dark matter halos. We present results from deep (365 ks) Chandra observations of the cluster, which reveal the most distant cold front (z=0.544) discovered to date. In the cluster outskirts, we also detect hints of a surface brightness edge that could be the bow shock preceding the cold front. The substructure analysis of the cluster identified several components with large relative radial velocities, thus indicating that at least some collisions occur almost along the line of sight. The inclination of the mergers with respect to the plane of the sky poses significant observational challenges at X-ray wavelengths. MACS J1149.6+2223 possibly hosts a steep-spectrum radio halo. If the steepness of the radio halo is confirmed, then the radio spectrum, combined with the relatively regular ICM morphology, could indicate that MACS J1149.6+2223 is an old merging cluster.

  1. Performance Investigation of 802.11 MAC DCF

    Directory of Open Access Journals (Sweden)

    Siddharth Dutt Choubey

    2012-10-01

    Full Text Available In the 802.11 protocol, DCF can be termed as an important mechanism in order to access the medium (Channel. This scheme is a random access based scheme which has its fundamentals based upon the efficient usage of CSMA/CA protocol. The retransmission of various collided packets is effectively managed in accordance with the Binary exponential Back-off rules. The waiting time of the BEB is exponentially increased by 2 after every unsuccessful transmission. Every successful transmission sets the back-off stage to initial stage and the contention window is also subsequently set to minimum regardless of any network conditions like the various n number of competing nodes. As the number of competing nodes rises, it can cause substantial performance deprivation as a result of the new collisions caused. This paper highlights and investigates the various modifications possible in the basic calculating methodology of the CW size after every successful transmission and collision of the BEB algorithm and it also evaluates the performance through different simulations possible for it. This paper also throws some significant light on the comparative study conducted on the throughput, end to end delay and packet loss ratio of the investigated schemes along with conventional DCF & one –another.

  2. THE DESIGN AND IMPLEMENTATION OF THE IEEE 802.11 MAC BASED ON SOFT-CORE PROCESSOR AND RTOS

    Institute of Scientific and Technical Information of China (English)

    Xiao Wan'ang; Fang Zhi; Shi Yin

    2007-01-01

    The implementation method of the IEEE 802.11 Medium Access Control (MAC) protocol is mainly based on DSP (Digital Signal Processor)/ARM (Advanced Reduced instruction set computer Machine) processor or DSP/ARM IP (Intellectual Property) core. This paper presents a method based on Nios Ⅱ soft-core processor embedded in Altera's Cyclone FPGA (Field Programmable Gate Array)and MicroC/OS-Ⅱ RTOS (Real-Time Operation System). The benefits and drawbacks of above methods are compared, and then the method presented in this paper is described. The hardware and software partitioning are discussed; the hardware architecture is also illustrated and the MAC software programming is described in detail. The presented method has some advantages, such as low cost,easy-implementation and very suitable for the implementation of IEEE 802.11 MAC in research stage.

  3. Evaluation of Integrated Routing/MAC Solutions for the Diffusion of Warning Messages in VANETs

    Directory of Open Access Journals (Sweden)

    Luca Campelli

    2007-12-01

    Full Text Available The efficiency of routing protocols in general mobile ad hoc networks may be highly affected by the specific Medium Access Control scheme the routing relies upon and by the mobility of the wireless nodes. In this work, we address the design of position based routing solutions for the support of safety oriented applications in Vehicular Ad hoc NETworks (VANETs by focusing on the impact of the MAC layer on the performances of the routing strategies. Namely, we propose a simulation analysis in highway scenarios to assess the routing performance in the two cases where standard IEEE 802.11 technology and a dynamic TDMA scheme are adopted at layer 2 respectively. We discuss on the dimensioning of the routing parameters in both cases and we provide a comparative analysis of the two MAC/routing integrated solutions.

  4. A Novel Video Data-Source Authentication Model Based on Digital Watermarking and MAC in Multicast

    Institute of Scientific and Technical Information of China (English)

    ZHAO Anjun; LU Xiangli; GUO Lei

    2006-01-01

    A novel video data authentication model based on digital video watermarking and MAC (message authentication code) in multicast protocol is proposed in this paper. The digital watermarking which composes of the MAC of the significant video content, the key and instant authentication data is embedded into the insignificant video component by the MLUT (modified look-up table) video watermarking technology. We explain a method that does not require storage of each data packet for a time, thus making receiver not vulnerable to DOS (denial of service) attack. So the video packets can be authenticated instantly without large volume buffer in the receivers. TESLA(timed efficient stream loss-tolerant authentication) does not explain how to select the suitable value for d, which is an important parameter in multicast source authentication. So we give a method to calculate the key disclosure delay (number of intervals). Simulation results show that the proposed algorithms improve the performance of data source authentication in multicast.

  5. Notas sobre dois livros de MacIntyre Notes on two books by MacIntyre

    Directory of Open Access Journals (Sweden)

    Isabel Ribeiro de Oliveira

    2005-04-01

    Full Text Available Os conceitos centrais da teoria da justiça desenvolvida por Alasdair MacIntyre - prática, narrativa e tradição - ocupam o núcleo da análise feita acerca de dois de seus livros: Depois da Virtude e Justiça de Quem? Qual racionalidade?. O artigo considera a relação, em MacIntyre, entre ética e história, virtude e relativismo, bem como apresenta seu conceito do Eu, como corretivos à anomia contemporânea.The central concepts of MacIntyre's approach to justice - practice, narrative and tradition - constitute the main trust of the analysis of two of his books: After Virtue and Whose justice? Which rationality? The article elaborates on the relationship of ethics to history, of virtues to relativism as well as his conception of the self as correctives to the pervasive anomie in contemporary societies.

  6. CSMA/CCA: A Modified CSMA/CA Protocol Mitigating the Fairness Problem for IEEE 802.11 DCF

    Directory of Open Access Journals (Sweden)

    2006-01-01

    Full Text Available Carrier sense multiple access with collision avoidance (CSMA/CA has been adopted by the IEEE 802.11 standards for wireless local area networks (WLANs. Using a distributed coordination function (DCF, the CSMA/CA protocol reduces collisions and improves the overall throughput. To mitigate fairness issues arising with CSMA/CA, we develop a modified version that we term CSMA with copying collision avoidance (CSMA/CCA. A station in CSMA/CCA contends for the shared wireless medium by employing a binary exponential backoff similar to CSMA/CA. Different from CSMA/CA, CSMA/CCA copies the contention window (CW size piggybacked in the MAC header of an overheard data frame within its basic service set (BSS and updates its backoff counter according to the new CW size. Simulations carried out in several WLAN configurations illustrate that CSMA/CCA improves fairness relative to CSMA/CA and offers considerable advantages for deployment in the 802.11-standard-based WLANs.

  7. MC2: Dynamical Analysis of the Merging Galaxy Cluster MACS J1149.5+2223

    Science.gov (United States)

    Golovich, Nathan; Dawson, William A.; Wittman, David; Ogrean, Georgiana; van Weeren, Reinout; Bonafede, Annalisa

    2016-11-01

    We present an analysis of the merging cluster MACS J1149.5+2223 using archival imaging from Subaru/Suprime-Cam and multi-object spectroscopy from Keck/DEIMOS and Gemini/GMOS. We employ two- and three-dimensional substructure tests and determine that MACS J1149.5+2223 is composed of two separate mergers among three subclusters occurring ˜1 Gyr apart. The primary merger gives rise to elongated X-ray morphology and a radio relic in the southeast. The brightest cluster galaxy is a member of the northern subcluster of the primary merger. This subcluster is very massive ({16.7}-1.60+1.25× {10}14 {M}⊙ ). The southern subcluster is also very massive ({10.8}-3.54+3.37× {10}14 {M}⊙ ), yet it lacks an associated X-ray surface brightness peak, and it has been unidentified previously despite the detailed study of this Frontier Field cluster. A secondary merger is occurring in the north along the line of sight (LOS) with a third, less massive subcluster ({1.20}-0.34+0.19× {10}14 {M}⊙ ). We perform a Monte Carlo dynamical analysis on the main merger and estimate a collision speed at pericenter of {2770}-310+610 km s-1. We show the merger to be returning from apocenter with core passage occurring {1.16}-0.25+0.50 Gyr before the observed state. We identify the LOS merging subcluster in a strong lensing analysis in the literature and show that it is likely bound to MACS J1149 despite having reached an extreme collision velocity of ˜4000 km s-1.

  8. Monitored Anaesthesia Care (MAC in antalgic surgery

    Directory of Open Access Journals (Sweden)

    Giovanni Maria Pisanu

    2011-09-01

    Full Text Available The use of surgical techniques for pain relief in the treatment of chronic-persistent pain unresponsive to drug therapy is experiencing a growing spread application in algology. These techniques have set themselves the goal of removing the pain after treatment. Therefore, not always, percutaneous or open procedures are carried out with due precaution necessary to alleviate the patient discomfort and suffering during the surgical intervention. We present our personal experience in the use of this technique Monitored Anaesthesia Care (MAC for patients undergoing surgical treatment of pain management at our Regional Center of Pain Management.

  9. One of the First Portable Macs

    CERN Multimedia

    1989-01-01

    It was one of the first portable macs released. The Portable had many new advances in mobile computing : The display was crispy clear, and looked beautiful when used in daylight ; The Portable came with a Lead-acid gel/cell battery that could run a anywhere from 6 -12 hours ; It supported to internal hard drives, and an external one. The reaction to the laptop was weak because it was slow, it had no capacity for expansion, it weighed heavily, its price was expensive. It has been stayed 1 year and half on the market.

  10. Implementation of MAC by using Modified Vedic Multiplier

    OpenAIRE

    2013-01-01

    Multiplier Accumulator Unit (MAC) is a part of Digital Signal Processors. The speed of MAC depends on the speed of multiplier. So by using an efficient Vedic multiplier which excels in terms of speed, power and area, the performance of MAC can be increased. For this fast method of multiplication based on ancient Indian Vedic mathematics is proposed in this paper. Among various method of multiplication in Vedic mathematics, Urdhva Tiryagbhyam is used and the multiplication is for 32 X 32 bits....

  11. Essential Mac OS X panther server administration integrating Mac OS X server into heterogeneous networks

    CERN Document Server

    Bartosh, Michael

    2004-01-01

    If you've ever wondered how to safely manipulate Mac OS X Panther Server's many underlying configuration files or needed to explain AFP permission mapping--this book's for you. From the command line to Apple's graphical tools, the book provides insight into this powerful server software. Topics covered include installation, deployment, server management, web application services, data gathering, and more

  12. Design and Analysis of an Attack Resilient and Adaptive Medium access Control Protocol for Computer Networks

    CERN Document Server

    Shukla, Piyush Kumar; Bhadoria, Dr Sarita Singh

    2009-01-01

    The challenge of designing an efficient Medium Access Control (MAC) protocol and analyzing it has been an important research topic for over 30 years. This paper focuses on the performance analysis (through simulation) and modification of a well known MAC protocol CSMA/CD. The existing protocol does not consider the wastage of bandwidth due to unutilized periods of the channel. By considering this fact, performance of MAC protocol can be enhanced. The purpose of this work is to modify the existing protocol by enabling it to adapt according to state of the network. The modified protocol takes appropriate action whenever unutilized periods detected. In this way, to increase the effective bandwidth utilization and determine how it behaves under increasing load, and varying packet sizes. It will also include effects of attacks i.e. Denial of service attacks, Replay Attack, Continuous Channel Access or Exhaustion attack, Flooding attack, Jamming (Radio interference) attack, Selective forwarding attack which degrade...

  13. A new latency-reducing and energy-efficient protocol for the wireless sensor network

    Institute of Scientific and Technical Information of China (English)

    XIONG Junjie; QU Yugui; LIN Huahui; PAN Quanke; ZHAO Baohua

    2007-01-01

    This paper introduces a new protocol routing medium access control (RMAC) that integrates the routing and medium access control (MAC) layer protocol.They can both reduce latency and save energy in the wireless sensor network (WSN) while most others propose protocols that sacrifice latency for energy.To make RMAC fit WSN better,we designed an easy and efficient routing protocol base station flooding (BSF) and then integrated it with a MAC protocol timing out MAC (TMAC) [1],while traditionally BSF and TMAC work separately at two layers.We call this two-layer protocol (TLP).We theoretically proved the advantages of RMAC over TLP and evaluated RMAC over NS-2.The simulation results show that RMAC spends half the latency of TLP,as well as consumes less energy than TLE

  14. Mac OS X Snow Leopard Server For Dummies

    CERN Document Server

    Rizzo, John

    2009-01-01

    Making Everything Easier!. Mac OS® X Snow Leopard Server for Dummies. Learn to::;. Set up and configure a Mac network with Snow Leopard Server;. Administer, secure, and troubleshoot the network;. Incorporate a Mac subnet into a Windows Active Directory® domain;. Take advantage of Unix® power and security. John Rizzo. Want to set up and administer a network even if you don't have an IT department? Read on!. Like everything Mac, Snow Leopard Server was designed to be easy to set up and use. Still, there are so many options and features that this book will save you heaps of time and effort. It wa

  15. Study on intracellular trafficking of Mac-1 by direct visualization

    Institute of Scientific and Technical Information of China (English)

    YAN Ming; MAO Jifang; WEI Yi; ZHONG Jigen; YANG Shengsheng; XU Renbao

    2004-01-01

    Previously, we constructed DNA vectors containing cDNA of Mac-1 subunits (CD11b or CD18b) fused with fluorescence protein (FP). cDNA fragments and the DNA constructs were then transfected into CHO cells (as CHO-Mac-1-FP). The structure and function of Mac-1-FP obtained from the CHO-Mac-1-FP cells are nearly identical to that expressed in wild type leukocytes. In the present study, the intracellular trafficking of Mac-1 was visualized directly by monitoring the fluorescent intensities of YFP-CD18 and PE-conjugated monoclonal antibody against CD11b under a confocal microscope in CHO-Mac-1-FP cells. The results indicate that: (ⅰ) although Mac-1 was not detected in the cell membrane at resting state, it had been translocated and clustered into the cell membrane by 1 h and internalized 2 h after PMA stimulation, at which point the fluorescence intensity began to diminish gradually, probably due to partial degradation of Mac-1. The fluorescence of CD18 and CD11b reappeared on the cell membrane 1 h after re-treatment with PMA, suggesting the recycling of non-degraded Mac-1. (ⅱ) The adhesion rate of CHO-Mac-1-FP to magnetic beads coupled ICAM-1 increased within 4 h after their initial interaction, accompanied by the clustering of Mac-1-FP. After 8 h,the adhesion rate declined and fluorescence also decreased simultaneously. The pattern of change in fluorescence in CHO-Mac-1-FP cells elicited by ICAM-1 beads was similar to that elicited by PMA, suggesting that endocytosis and degradation of Mac-1 occurred after the interaction with ICAM-1. Thus, we conclude that the intracellular trafficking of Mac-1 after activation is associated with membrane translocation, endocytosis, degradation and recycling. These changes are in parallel with the adhesion of CHO-Mac-1-FP cells with ICAM-1, and may be involved in the adhesion and detachment of leukocytes. The detachment of leukocytes may be caused by endocytosis of Mac-1.

  16. Pliable Cognitive MAC for Heterogeneous Adaptive Cognitive Radio Sensor Networks.

    Directory of Open Access Journals (Sweden)

    Mohammed Al-Medhwahi

    Full Text Available The rapid expansion of wireless monitoring and surveillance applications in several domains reinforces the trend of exploiting emerging technologies such as the cognitive radio. However, these technologies have to adjust their working concepts to consider the common characteristics of conventional wireless sensor networks (WSNs. The cognitive radio sensor network (CRSN, still an immature technology, has to deal with new networks that might have different types of data, traffic patterns, or quality of service (QoS requirements. In this paper, we design and model a new cognitive radio-based medium access control (MAC algorithm dealing with the heterogeneous nature of the developed networks in terms of either the traffic pattern or the required QoS for the node applications. The proposed algorithm decreases the consumed power on several fronts, provides satisfactory levels of latency and spectrum utilization with efficient scheduling, and manages the radio resources for various traffic conditions. An intensive performance evaluation is conducted to study the impact of key parameters such as the channel idle time length, node density, and the number of available channels. The performance evaluation of the proposed algorithm shows a better performance than the comparable protocols. Moreover, the results manifest that the proposed algorithm is suitable for real time monitoring applications.

  17. Pliable Cognitive MAC for Heterogeneous Adaptive Cognitive Radio Sensor Networks.

    Science.gov (United States)

    Al-Medhwahi, Mohammed; Hashim, Fazirulhisyam; Ali, Borhanuddin Mohd; Sali, Aduwati

    2016-01-01

    The rapid expansion of wireless monitoring and surveillance applications in several domains reinforces the trend of exploiting emerging technologies such as the cognitive radio. However, these technologies have to adjust their working concepts to consider the common characteristics of conventional wireless sensor networks (WSNs). The cognitive radio sensor network (CRSN), still an immature technology, has to deal with new networks that might have different types of data, traffic patterns, or quality of service (QoS) requirements. In this paper, we design and model a new cognitive radio-based medium access control (MAC) algorithm dealing with the heterogeneous nature of the developed networks in terms of either the traffic pattern or the required QoS for the node applications. The proposed algorithm decreases the consumed power on several fronts, provides satisfactory levels of latency and spectrum utilization with efficient scheduling, and manages the radio resources for various traffic conditions. An intensive performance evaluation is conducted to study the impact of key parameters such as the channel idle time length, node density, and the number of available channels. The performance evaluation of the proposed algorithm shows a better performance than the comparable protocols. Moreover, the results manifest that the proposed algorithm is suitable for real time monitoring applications.

  18. Comparison of ICM with TPF-LEP to Prevent MAC Spoof DoS Attack in Wireless Local Area Infrastructure Network

    Directory of Open Access Journals (Sweden)

    M. Durairaj

    2014-05-01

    Full Text Available A Comparison of Integrated Central Manager (ICM and Traffic Pattern Filtering with Letter Envelop Protocol (TPF-LEP is done. Denial of Service (DoS attack is a biggest peril in wireless local area infrastructure network. It makes the resources unavailable for intended users which transpired through spoofing legitimate Client/AP's Medium Access Control (MAC address. MAC address are easily caricatured by the adversary clients, subsequently they are not encrypted. Since, the adversary sends the management frame, which is unencrypted, to the victim using spoofed MAC address. This study compares the performance of Integrated Central Manager (ICM and Traffic Pattern Filtering with Letter Envelop Protocol (TPF-LEP and evaluated the result using NS2. The attack scenario is simulated and effectiveness of the solutions is validated after the instigation of solutions in the attack consequences. Throughput, Packet Delivery Ratio and Packet Loss are measured and taken to endorse the performance of ICM and TPF-LEP.

  19. SACRB-MAC: A High-Capacity MAC Protocol for Cognitive Radio Sensor Networks in Smart Grid

    OpenAIRE

    Zhutian Yang; Zhenguo Shi; Chunlin Jin

    2016-01-01

    The Cognitive Radio Sensor Network (CRSN) is considered as a viable solution to enhance various aspects of the electric power grid and to realize a smart grid. However, several challenges for CRSNs are generated due to the harsh wireless environment in a smart grid. As a result, throughput and reliability become critical issues. On the other hand, the spectrum aggregation technique is expected to play an important role in CRSNs in a smart grid. By using spectrum aggregation, the throughput of...

  20. 42 CFR 405.1122 - What evidence may be submitted to the MAC.

    Science.gov (United States)

    2010-10-01

    ... 42 Public Health 2 2010-10-01 2010-10-01 false What evidence may be submitted to the MAC. 405.1122... Council Review § 405.1122 What evidence may be submitted to the MAC. (a) Appeal before the MAC on request for review of ALJ's decision. (1) If the MAC is reviewing an ALJ's decision, the MAC limits its review...

  1. 42 CFR 423.2122 - What evidence may be submitted to the MAC.

    Science.gov (United States)

    2010-10-01

    ... 42 Public Health 3 2010-10-01 2010-10-01 false What evidence may be submitted to the MAC. 423.2122..., MAC review, and Judicial Review § 423.2122 What evidence may be submitted to the MAC. (a) Appeal before the MAC on request for review of ALJ's decision. (1) If the MAC is reviewing an ALJ's decision...

  2. Efficient medium access control protocol for geostationary satellite systems

    Institute of Scientific and Technical Information of China (English)

    王丽娜; 顾学迈

    2004-01-01

    This paper proposes an efficient medium access control (MAC) protocol based on multifrequency-time division multiple access (MF-TDMA) for geostationary satellite systems deploying multiple spot-beams and onboard processing,which uses a method of random reservation access with movable boundaries to dynamically request the transmission slots and can transmit different types of traffic. The simulation results have shown that our designed MAC protocol can achieve a high bandwidth utilization, while providing the required quality of service (QoS) for each class of service.

  3. Influence of prior determination of baseline minimum alveolar concentration (MAC) of isoflurane on the effect of ketamine on MAC in dogs.

    Science.gov (United States)

    Gianotti, Giacomo; Valverde, Alexander; Johnson, Ron; Sinclair, Melissa; Gibson, Thomas; Dyson, Doris H

    2014-07-01

    The objective of this study was to determine if prior measurement of the minimum alveolar concentration (MAC) of isoflurane influences the effect of ketamine on the MAC of isoflurane in dogs. Eight mixed-breed dogs were studied on 2 occasions. Anesthesia was induced and maintained using isoflurane. In group 1 the effect of ketamine on isoflurane MAC was determined after initially finding the baseline isoflurane MAC. In group 2, the effect of ketamine on isoflurane MAC was determined without previous measure of the baseline isoflurane MAC. In both groups, MAC was determined again 30 min after stopping the CRI of ketamine. Plasma ketamine concentrations were measured during MAC determinations. In group 1, baseline MAC (mean ± SD: 1.18 ± 0.14%) was decreased by ketamine (0.88 ± 0.14%; P MAC after stopping ketamine was similar (1.09 ± 0.16%) to baseline MAC and higher than with ketamine (P MAC with ketamine (0.79 ± 0.11%) was also increased after stopping ketamine (1.10 ± 0.17%; P MAC values with ketamine were different between groups (P MAC determination. The MAC of isoflurane during the CRI of ketamine yielded different results when methods of same day (group-1) versus separate days (group-2) are used, despite similar plasma ketamine concentrations with both methods. However, because the magnitude of this difference was less than 10%, either method of determining MAC is deemed acceptable for research purposes.

  4. On the orthogonality of the MacDonald s functions

    Energy Technology Data Exchange (ETDEWEB)

    Passian, Ali [ORNL; Simpson, Henry [University of Tennessee, Knoxville (UTK); Koucheckian, Sherwin [University of South Florida, Tampa; Yakubovich, Semyon [University of Porto, Portugal

    2009-01-01

    A proof of an orthogonality relation for the MacDonald's functions with identical arguments but unequal complex lower indices is presented. The orthogonality is derived first via a heuristic approach based on the Mehler-Fock integral transform of the MacDonald's functions, and then proved rigorously using a polynomial approximation procedure.

  5. SuperMacLang: Development of an Authoring System.

    Science.gov (United States)

    Frommer, Judith; Foelsche, Otmar K. E.

    1999-01-01

    Describes the development of "SuperMacLang, the 1990s version of the MacLang authoring system. An analysis of various features of the program explains the ways in which certain aspects of collaboration and funding affected developer and programming decisions. (Author/VWL)

  6. Steven MacCall: Winner of LJ's 2010 Teaching Award

    Science.gov (United States)

    Berry, John N., III

    2010-01-01

    This article profiles Steven L. MacCall, winner of "Library Journal's" 2010 Teaching Award. An associate professor at the School of Library and Information Studies (SLIS) at the University of Alabama, Tuscaloosa, MacCall was nominated by Kathie Popadin, known as "Kpop" to the members of her cohort in the online MLIS program at SLIS. Sixteen of…

  7. Intel-Based Mac Computers Improve Teaching and Learning

    Science.gov (United States)

    Technology & Learning, 2007

    2007-01-01

    Today, Mac computers offer schools an easy and powerful way to engage students in learning, foster 21st century skills and leverage existing software assets. Innovative software and hardware built into the Mac allows students to demonstrate their individual strengths--empowering them to be creators of content, rather than just consumers. Judging…

  8. Intel-Based Mac Computers Improve Teaching and Learning

    Science.gov (United States)

    Technology & Learning, 2007

    2007-01-01

    Today, Mac computers offer schools an easy and powerful way to engage students in learning, foster 21st century skills and leverage existing software assets. Innovative software and hardware built into the Mac allows students to demonstrate their individual strengths--empowering them to be creators of content, rather than just consumers. Judging…

  9. Steven MacCall: Winner of LJ's 2010 Teaching Award

    Science.gov (United States)

    Berry, John N., III

    2010-01-01

    This article profiles Steven L. MacCall, winner of "Library Journal's" 2010 Teaching Award. An associate professor at the School of Library and Information Studies (SLIS) at the University of Alabama, Tuscaloosa, MacCall was nominated by Kathie Popadin, known as "Kpop" to the members of her cohort in the online MLIS program at SLIS. Sixteen of…

  10. A New Formal Method for Communication Protocol Specification

    Institute of Scientific and Technical Information of China (English)

    李腊元

    1989-01-01

    A new formal method for communication protocol specification is presented.FSM,CSP and ADT are mixed and the best features of these approaches can be offered in the fomal method.First,we briefly describe the formal techniques of communication protocol.We then put forward the hybrid method of protocol specification.Finally,an example,i.e.,IEEE 802.3 MAC protocol for LAN described by the proposed formal method,is given.The results of studies show that this hybrid formal method for protocol specification is a correct,unambiguous and complete approach.

  11. Design and Implementation of an Enhanced 802.11 MAC Architecture for Single-Hop Wireless Networks

    Directory of Open Access Journals (Sweden)

    Ralph Bernasconi

    2007-01-01

    Full Text Available Due to its extreme simplicity and flexibility, the IEEE 802.11 standard is the dominant technology to implement both infrastructure-based WLANs and single-hop ad hoc networks. In spite of its popularity, there is a vast literature demonstrating the shortcomings of using the 802.11 technology in such environments, such as dramatic degradation of network capacity as contention increases and vulnerability to external interferences. Therefore, the design of enhancements and optimizations for the original 802.11 MAC protocol has been a very active research area in the last years. However, all these modifications to the 802.11 MAC protocol were validated only through simulations and/or analytical investigations. In this paper, we present a very unique work as we have designed a flexible hardware/software platform, fully compatible with current implementations of the IEEE 802.11 technology, which we have used to concretely implement and test an enhanced 802.11 backoff algorithm. Our experimental results clearly show that the enhanced mechanism outperforms the standard 802.11 MAC protocol in real scenarios.

  12. Equivalent Key Recovery Attack on H2-MAC Instantiated with MD5%H2-MAC-MD5的等价密钥恢复攻击

    Institute of Scientific and Technical Information of China (English)

    王薇

    2012-01-01

    H2-MAC was proposed by Kan Yasuda in Information Security Conference (ISC) 2009, which is similar with HMAC except that the outer key is omitted, and gets rid of the disadvantage of the key management. This paper presents the first equivalent key recovery attack on H2-MAC-MD5, which conduces to a selective forgery attack directly, while there only is a distinguishing attack for HMAC-MD5. Based on the distinguisher of HMAC-MD5, a pair of intermediate chaining variables, i.e., the equivalent keys, is detected which fulfils the specific conditions on the initial variables of the pseudo-collision. Then the inner key recovery attack on HMAC-MD5 is adopted to recover the equivalent key. Consequently, the adversary can process the selective forgery attack by computing the valid MAC value of M0||M*effortlessly, where M0 is a fixed one-block message, and M*can be any bit strings. The complexity of the attack is about 297 queries, which is much lower than the ideal complexity of the selective forgery.%H2-MAC由Kan Yasuda在ISC 2009上提出,与HMAC的不同之处在于H2-MAC没有外部密钥,简化密钥管理。首次给出 H2-MAC-MD5的等价密钥恢复攻击,并进行选择性伪造。基于HMAC-MD5区分器和比特探测技术,筛选可能满足特殊伪碰撞路线的中间链接变量,即等价密钥,并恢复其数值,导致选择性伪造。即在不知道密钥的前提下,敌手可伪造消息M0||M*的合法MAC值,其中,M0为固定的512比特消息分组,M*为任意消息。攻击的复杂度为297次MAC查询,远低于选择性伪造攻击的理想复杂度。

  13. Action principle for Coulomb collisions in plasmas

    Science.gov (United States)

    Hirvijoki, Eero

    2016-09-01

    An action principle for Coulomb collisions in plasmas is proposed. Although no natural Lagrangian exists for the Landau-Fokker-Planck equation, an Eulerian variational formulation is found considering the system of partial differential equations that couple the distribution function and the Rosenbluth-MacDonald-Judd potentials. Conservation laws are derived after generalizing the energy-momentum stress tensor for second order Lagrangians and, in the case of a test-particle population in a given plasma background, the action principle is shown to correspond to the Langevin equation for individual particles.

  14. McCay ("Mac") Vernon (1928-2013).

    Science.gov (United States)

    Sherman, William A

    2014-09-01

    McCay ("Mac") Vernon, the founding and preeminent psychologist in the field of deafness. Mac was born at Walter Reed Hospital in Washington, DC, into a military family on October 14, 1928 and died on August 28, 2013, at the age of 84. Prior to Mac, research and clinical direction in the field were sparse. Mac became the icon for psychological services for deaf people, and his work extended into the education of deaf children, forensic and ethical practices with the deaf, and public understanding of deafness as a disability and of deaf persons as a psychosocial minority group. Mac will also be remembered for his sharp intellect, good humor, compassion, and advocacy for those who are misunderstood.

  15. An Efficient Medium Access Control Protocol with Parallel Transmission for Wireless Sensor Networks

    Directory of Open Access Journals (Sweden)

    Mitsuji Matsumoto

    2012-08-01

    Full Text Available In this paper, we present a novel low power medium access control protocol for wireless sensor networks (WSNs. The proposed protocol, EP-MAC (Efficient MAC with Parallel Transmission achieves high energy efficiency and high packet delivery ratio under different traffic load. EP-MAC protocol is basically based on the Time Division Multiple Access (TDMA approach. The power of Carrier Sense Multiple Access (CSMA is used in order to offset the fundamental problems that the stand-alone TDMA method suffers from, i.e., problems such as lack of scalability, adaptability to varying situations, etc. The novel idea behind the EP-MAC is that it uses the parallel transmission concept with the TDMA link scheduling. EP-MAC uses the methods for the transmission power adjustment, i.e., uses the minimum level power necessary to reach the intended neighbor within a specified bit error rate [BER] target. This reduces energy consumption, as well as further enhances the scope of parallel transmission of the protocol. The simulation studies support the theoretical results, and validate the efficiency of our proposed EP-MAC protocol.

  16. Specific amplification of gene encoding N-terminal region of catalase-peroxidase protein (KatG-N) for diagnosis of disseminated MAC disease in HIV patients.

    Science.gov (United States)

    Latawa, Romica; Singh, Krishna Kumar; Wanchu, Ajay; Sethi, Sunil; Sharma, Kusum; Sharma, Aman; Laal, Suman; Verma, Indu

    2014-10-01

    Disseminated Mycobacterium avium-intracellulare complex (MAC) infection is considered as severe complication of advanced HIV/AIDS disease. Currently available various laboratory investigations have not only limited ability to discriminate between MAC infection and tuberculosis but are also laborious and time consuming. The aim of this study was, therefore, to design a molecular-based strategy for specific detection of MAC and its differentiation from Mycobacterium tuberculosis (M. tb) isolated from the blood specimens of HIV patients. A simple PCR was developed based on the amplification of 120-bp katG-N gene corresponding to the first 40 amino acids of N-terminal catalase-peroxidase (KatG) protein of Mycobacterium avium that shows only ~13% sequence homology by clustal W alignment to N-terminal region of M. tb KatG protein. This assay allowed the accurate and rapid detection of MAC bacteremia, distinguishing it from M. tb in a single PCR reaction without any need for sequencing or hybridization protocol to be performed thereafter. This study produced enough evidence that a significant proportion of Indian HIV patients have disseminated MAC bacteremia, suggesting the utility of M. avium katG-N gene PCR for early detection of MAC disease in HIV patients. Copyright © 2014 Elsevier Inc. All rights reserved.

  17. Alasdair MacIntyre, joven lector de Freud

    Directory of Open Access Journals (Sweden)

    Ramis Barceló, Rafael

    2010-06-01

    Full Text Available This article tries to show the reading of Freud that MacIntyre made from 1955 to 1970. For this purpose, it summarizes the ideas of MacIntyre in the intellectual context, mainly the use of philosophical ideas of Freud against the Enlightenment project. MacIntyre criticises Marxist interpreters and the mixing between Marx and Freud. MacIntyre uses the philosophical ideas of Freud for answering two problems on determinism: the links between determinism and reasons for action and determinism and Marxism. The main conclusion is that MacIntyre used Freud in his own advantage: as an ally in the criticism of the Enlightenment.

    Este artículo trata de mostrar la lectura que MacIntyre hizo de Freud desde 1955 hasta 1970. Con este fin, se resumen las ideas de MacIntyre en el contexto intelectual, principalmente el uso de las ideas filosóficas de Freud contra el proyecto de la Ilustración. MacIntyre critica a los intérpretes de Marx y a la mezcla entre Marx y Freud. MacIntyre usa las ideas filosóficas de Freud para contestar dos problemas sobre el determinismo: los vínculos entre el determinismo y las razones para la acción y el determinismo y el marxismo. La conclusión principal es que MacIntyre usó a Freud en su propio beneficio: como un aliado en la crítica de la Ilustración.

  18. Wireless vehicular networks for car collision avoidance

    CERN Document Server

    2013-01-01

    Wireless Vehicular Networks for Car Collision Avoidance focuses on the development of the ITS (Intelligent Transportation Systems) in order to minimize vehicular accidents. The book presents and analyses a range of concrete accident scenarios while examining the causes of vehicular collision and proposing countermeasures based on wireless vehicular networks. The book also describes the vehicular network standards and quality of service mechanisms focusing on improving critical dissemination of safety information. With recommendations on techniques and protocols to consider when improving road safety policies in order to minimize crashes and collision risks.

  19. The minimum alveolar concentration (MAC) of isoflurane in preterm neonates.

    Science.gov (United States)

    LeDez, K M; Lerman, J

    1987-09-01

    Studies in fetal lambs suggested that the minimum alveolar concentration (MAC) in preterm neonates may be less than that in full-term neonates and older infants. To determine the MAC of isoflurane in preterm neonates, 20 patients less than 32 weeks gestation at birth and 16 patients 32-37 weeks gestation at birth, all less than 1 month post-natal age, were studied. Following tracheal intubation, the neonates were anesthetized with a predetermined end-tidal concentration of isoflurane in oxygen and air. The move-no move responses to skin incision were recorded, and MAC was determined using the "up-and-down" technique. Heart rate and systolic arterial pressure were recorded awake, before skin incision, and after skin incision. MAC (mean +/- SD) of isoflurane in preterm neonates less than 32 weeks gestation was 1.28 +/- 0.17%, and MAC in neonates 32-37 weeks gestation was 1.41 +/- 0.18% (P less than 0.05). Although heart rate did not decrease significantly in either group during the study, systolic arterial pressure decreased between 20 and 30% below awake values both before and after skin incision in both age groups (P less than 0.01). We conclude that the MAC of isoflurane in preterm neonates less than 32 weeks gestation is significantly less than that in preterm neonates 32-37 weeks gestation, and that systolic arterial pressure decreases to a similar extent at approximately 1 MAC isoflurane in both age groups.

  20. Semi-automated protocol for purification of Mycobacterium leprae from tissues using the gentleMACS™ Octo Dissociator

    Science.gov (United States)

    Williams, Diana L.; Adams, Linda B.; Lahiri, Ramanuj

    2014-01-01

    Mycobacterium leprae, etiologic agent of leprosy, is propagated in athymic nude mouse footpads (FPs). The current purification protocol is tedious and physically demanding. A simpler, semi-automated protocol was developed using gentleMACS™ Octo Dissociator. The gentleMACS protocol provided a very effective means for purification of highly viable M. leprae from tissue. PMID:25019518

  1. 基于USRP2的无线网络MAC协议半实物仿真系统设计与实现%Design and implementation of hardware-in-loop simulation system of wireless network MAC protocol in USRP2

    Institute of Scientific and Technical Information of China (English)

    李佳迅; 张少杰; 赵海涛; 马东堂

    2015-01-01

    目前,由于可供网络协议开发的硬件资源极其有限,而且真实性能评估要求硬件上的组网产生了高额的硬件成本.因此,对于大多数网络协议的研究以及性能评估都是基于纯软件系统进行的,其结果仅局限于理论意义.为了解决这些问题,基于GNU Radio平台以及二代通用软件无线电外设(USRP2)设计和实现了分布式无线网络媒体介入控制(MAC)协议的半实物仿真系统.该系统以IEEE802.11分布式协调功能(DCF)为协议框架,结合离散事件仿真技术,依靠较少的硬件资源(一台个人计算机(PC)和两台USRP2)模拟了多个节点的无线通信网络.实现中,MAC层协议使用简洁的Python语言进行系统开发,具有很大的灵活性,而且扩展性和可移植性强;物理层使用高效的C++语言对信号进行模块化处理,并利用USRP2射频硬件在真实信道上进行数据传输.将系统的节点发送概率以及吞吐量实测数据分别与Bianchi算法以及基于时隙分析的饱和吞吐量计算模型进行了对比,对比结果的吻合性说明了网络仿真平台的可靠性.

  2. Increased NMDA receptor inhibition at an increased Sevoflurane MAC

    Directory of Open Access Journals (Sweden)

    Brosnan Robert J

    2012-06-01

    Full Text Available Abstract Background Sevoflurane potently enhances glycine receptor currents and more modestly decreases NMDA receptor currents, each of which may contribute to immobility. This modest NMDA receptor antagonism by sevoflurane at a minimum alveolar concentration (MAC could be reciprocally related to large potentiation of other inhibitory ion channels. If so, then reduced glycine receptor potency should increase NMDA receptor antagonism by sevoflurane at MAC. Methods Indwelling lumbar subarachnoid catheters were surgically placed in 14 anesthetized rats. Rats were anesthetized with sevoflurane the next day, and a pre-infusion sevoflurane MAC was measured in duplicate using a tail clamp method. Artificial CSF (aCSF containing either 0 or 4 mg/mL strychnine was then infused intrathecally at 4 μL/min, and the post-infusion baseline sevoflurane MAC was measured. Finally, aCSF containing strychnine (either 0 or 4 mg/mL plus 0.4 mg/mL dizocilpine (MK-801 was administered intrathecally at 4 μL/min, and the post-dizocilpine sevoflurane MAC was measured. Results Pre-infusion sevoflurane MAC was 2.26%. Intrathecal aCSF alone did not affect MAC, but intrathecal strychnine significantly increased sevoflurane requirement. Addition of dizocilpine significantly decreased MAC in all rats, but this decrease was two times larger in rats without intrathecal strychnine compared to rats with intrathecal strychnine, a statistically significant (P  Conclusions Glycine receptor antagonism increases NMDA receptor antagonism by sevoflurane at MAC. The magnitude of anesthetic effects on a given ion channel may therefore depend on the magnitude of its effects on other receptors that modulate neuronal excitability.

  3. Increased NMDA receptor inhibition at an increased Sevoflurane MAC.

    Science.gov (United States)

    Brosnan, Robert J; Thiesen, Roberto

    2012-06-06

    Sevoflurane potently enhances glycine receptor currents and more modestly decreases NMDA receptor currents, each of which may contribute to immobility. This modest NMDA receptor antagonism by sevoflurane at a minimum alveolar concentration (MAC) could be reciprocally related to large potentiation of other inhibitory ion channels. If so, then reduced glycine receptor potency should increase NMDA receptor antagonism by sevoflurane at MAC. Indwelling lumbar subarachnoid catheters were surgically placed in 14 anesthetized rats. Rats were anesthetized with sevoflurane the next day, and a pre-infusion sevoflurane MAC was measured in duplicate using a tail clamp method. Artificial CSF (aCSF) containing either 0 or 4 mg/mL strychnine was then infused intrathecally at 4 μL/min, and the post-infusion baseline sevoflurane MAC was measured. Finally, aCSF containing strychnine (either 0 or 4 mg/mL) plus 0.4 mg/mL dizocilpine (MK-801) was administered intrathecally at 4 μL/min, and the post-dizocilpine sevoflurane MAC was measured. Pre-infusion sevoflurane MAC was 2.26%. Intrathecal aCSF alone did not affect MAC, but intrathecal strychnine significantly increased sevoflurane requirement. Addition of dizocilpine significantly decreased MAC in all rats, but this decrease was two times larger in rats without intrathecal strychnine compared to rats with intrathecal strychnine, a statistically significant (P MAC. The magnitude of anesthetic effects on a given ion channel may therefore depend on the magnitude of its effects on other receptors that modulate neuronal excitability.

  4. MacRuby Ruby and Cocoa on OS X

    CERN Document Server

    Aimonetti, Matt

    2011-01-01

    Want to build native Mac OS X applications with a sleek, developer-friendly alternative to Objective-C? MacRuby is an ideal choice. This in-depth guide shows you how Apple's implementation of Ruby gives you access to all the features available to Objective-C programmers. You'll get clear, detailed explanations of MacRuby, including quick programming techniques such as prototyping. Perfect for programmers at any level, this book is packed with code samples and complete project examples. If you use Ruby, you can tap your skills to take advantage of Interface Builder, Cocoa libraries, the Objec

  5. A Hybrid MacCormack-type Scheme for Computational Aeroacoustics

    Science.gov (United States)

    Yazdani, Soroush

    A new type of MacCormack scheme, using a modified Low Dissipation and Dispersion Runge-Kutta time marching method, is presented. This scheme is using two stages in every step which implements biased spatial differencing stencils and for the remaining stages uses non-dissipative central differencing stencils. Because of using the MacCormack-type scheme in this method, the new scheme carries an inherent artificial dissipation which uses the ease of implementing boundary condition specifications of a two-stage MacCormack scheme.

  6. iMac G3 Blueberry 350MHz

    CERN Multimedia

    2000-01-01

    The iMac G3 is an all-in-one personal computer, encompassing both the monitor and the computer in one package. It allowed to revitalize the Apple brand that was in decline and close to financial ruin. Originally released in striking bondi blue and later a range of other translucent plastic envelopes in bright colors. The iMac comes with a keyboard and mouse matching the color of the case. The iMac G3 was sold from 1998 to 2003 and has been updated many times.

  7. THE INFLUENCE OF MAC BUFFER ON THE CONTENTION-BASED ACCESS SCHEME WITH BURSTING OPTION FOR IEEE 802.11E WIRELESS NETWORKS

    Directory of Open Access Journals (Sweden)

    S. SELVAKENNEDY

    2006-12-01

    Full Text Available Wireless LANs are increasingly being used for inelastic applications. Currently, there is little support for quality of service in the IEEE 802.11 MAC protocol, and IEEE task group E has defined the 802.11e MAC extension. Enhanced distributed channel access (EDCA is a contention-based scheme of the 802.11e standard. To allow a station to transmit more than one frame from a single contention, an optional feature known as controlled frame-bursting (CFB is introduced in the standard. In this paper, we initially performed an average analysis to determine a suitable burst duration limit. Then, a detailed evaluation and comparison of the EDCA protocol with the CFB option is carried out through simulation to quantify its performance gain. The impact of the MAC transmit buffer size is also incorporated. Accordingly, we have proposed a suitable approach to guide the configuration of the burst duration limit. It is demonstrated that an optimized CFB configuration allows the MAC protocol to achieve 30% more capacity than the basic EDCA scheme.

  8. Infecting Windows, Linux & Mac in one go

    CERN Multimedia

    Computer Security Team

    2012-01-01

    Still love bashing on Windows as you believe it is an insecure operating system? Hold on a second! Just recently, a vulnerability has been published for Java 7.   It affects Windows/Linux PCs and Macs, Internet Explorer, Safari and Firefox. In fact, it affects all computers that have enabled the Java 7 plug-in in their browser (Java 6 and earlier is not affected). Once you visit a malicious website (and there are plenty already out in the wild), your computer is infected… That's "Game Over" for you.      And this is not the first time. For a while now, attackers have not been targeting the operating system itself, but rather aiming at vulnerabilities inherent in e.g. your Acrobat Reader, Adobe Flash or Java programmes. All these are standard plug-ins added into your favourite web browser which make your web-surfing comfortable (or impossible when you un-install them). A single compromised web-site, however, is sufficient to prob...

  9. Prior determination of baseline minimum alveolar concentration (MAC) of isoflurane does not influence the effect of ketamine on MAC in rabbits.

    Science.gov (United States)

    Gianotti, Giacomo; Valverde, Alexander; Sinclair, Melissa; Dyson, Doris H; Gibson, Thomas; Johnson, Ron

    2012-10-01

    The objective of this study was to compare the effect on the minimum alveolar concentration (MAC) of isoflurane when ketamine was administered either after or without prior determination of the baseline MAC of isoflurane in rabbits. Using a prospective randomized crossover study, 8 adult, female New Zealand rabbits were allocated to 2 treatment groups. Anesthesia was induced and maintained with isoflurane. Group 1 (same-day determination) had the MAC-sparing effect of ketamine [1 mg/kg bodyweight (BW) bolus followed by a constant rate infusion (CRI) of 40 μg/kg BW per min, given by intravenous (IV)], which was determined after the baseline MAC of isoflurane was determined beforehand. A third MAC determination was started 30 min after stopping the CRI. Group 2 (separate-day determination) had the MAC-sparing effect of ketamine determined without previous determination of the baseline MAC of isoflurane. A second MAC determination was started 30 min after stopping the CRI. In group 1, the MAC of isoflurane (2.15 ± 0.09%) was significantly decreased by ketamine (1.63 ± 0.07%). After stopping the CRI, the MAC was significantly less (2.04 ± 0.11%) than the baseline MAC of isoflurane and significantly greater than the MAC during the CRI. In group 2, ketamine decreased isoflurane MAC (1.53 ± 0.22%) and the MAC increased significantly (1.94 ± 0.25%) after stopping the CRI. Minimum alveolar concentration (MAC) values did not differ significantly between the groups either during ketamine administration or after stopping ketamine. Under the study conditions, prior determination of the baseline isoflurane MAC did not alter the effect of ketamine on MAC. Both methods of determining MAC seemed to be valid for research purposes.

  10. Competition at the Wireless Sensor Network MAC Layer: Low Power Probing interfering with X-MAC

    Science.gov (United States)

    Zacharias, Sven; Newe, Thomas

    2011-08-01

    Wireless Sensor Networks (WSNs) combine sensors with computer networks and enable very dense, in-situ and live measurements of data over a large area. Since this emerging technology has the potential to be embedded almost everywhere for numberless applications, interference between different networks can become a serious issue. For most WSNs, it is assumed today that the network medium access is non-competitive. On the basis of X-MAC interfered by Low Power Probing, this paper shows the danger and the effects of different sensor networks communicating on a single wireless channel of the 2.4 GHz band, which is used by the IEEE 802.15.4 standard.

  11. After MacIntyre : Kaasaegsest vooruseetikast / Meego Remmel

    Index Scriptorium Estoniae

    Remmel, Meego

    2006-01-01

    Alasdair MacIntyre panus 20. sajandi eetikasse. Tema käsitlus vooruseetikast ja vooruseetilisest perspektiivist, mida on võimalik näha komplekselt, vaadeldes voorust, praktikat, narratiivi ja traditsiooni mõisteid

  12. After MacIntyre : Kaasaegsest vooruseetikast / Meego Remmel

    Index Scriptorium Estoniae

    Remmel, Meego

    2006-01-01

    Alasdair MacIntyre panus 20. sajandi eetikasse. Tema käsitlus vooruseetikast ja vooruseetilisest perspektiivist, mida on võimalik näha komplekselt, vaadeldes voorust, praktikat, narratiivi ja traditsiooni mõisteid

  13. Design and Implementation of an Efficient 64 bit MAC

    Directory of Open Access Journals (Sweden)

    Mohammad Shabber Hasan Khan

    2015-08-01

    Full Text Available The design of optimized 64 bit multiplier and accumulator (MAC unit is implemented in this paper. MAC unit plays major role in many of the digital signal processing (DSP applications. The MAC unit is designed with the combinations of multipliers and adders. In the proposed method MAC unit is implemented using Vedic multiplier and the adder is done with ripple carry adder .The components are reduced by implementing Vedic multiplier using the techniques of Vedic mathematics that have been modified to improve performance. a high speed processor depends significantly on the multiplier as it is one of the key hardware blocks in most digital signal processing systems as well as in general processors. The area is optimized effectively using Vedic multiplier .The total design implemented using Xilinx.

  14. Beamforming in Ad Hoc Networks: MAC Design and Performance Modeling

    National Research Council Canada - National Science Library

    Fakih, Khalil; Diouris, Jean-Francois; Andrieux, Guillaume

    2009-01-01

    .... Our proposition performs jointly channel estimation and radio resource sharing. We validate the fruitfulness of the proposed MAC and we evaluate the effects of the channel estimation on the network performance...

  15. Aeronautical Mobile Airport Communications System (AeroMACS)

    Science.gov (United States)

    Budinger, James M.; Hall, Edward

    2011-01-01

    To help increase the capacity and efficiency of the nation s airports, a secure wideband wireless communications system is proposed for use on the airport surface. This paper provides an overview of the research and development process for the Aeronautical Mobile Airport Communications System (AeroMACS). AeroMACS is based on a specific commercial profile of the Institute of Electrical and Electronics Engineers (IEEE) 802.16 standard known as Wireless Worldwide Interoperability for Microwave Access or WiMAX (WiMax Forum). The paper includes background on the need for global interoperability in air/ground data communications, describes potential AeroMACS applications, addresses allocated frequency spectrum constraints, summarizes the international standardization process, and provides findings and recommendations from the world s first AeroMACS prototype implemented in Cleveland, Ohio, USA.

  16. Rating of new outlet structures for MacFarlane Reservoir

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — Memorandum explaining the new work on the outlet structure at MacFarlane Reservoir. Flow measurements were taken at different staff gage elevations and this data is...

  17. Big Mac arvestab raha ostujõudu / Harli Uljas

    Index Scriptorium Estoniae

    Uljas, Harli

    2005-01-01

    The Economist võrdleb maailma valuutade suhestamiseks Big Mac'i burgeri hindu 120 riigis, kuna see meetod võimaldab saada ülevaate riikide elanikkonna tegelikust ostujõust. Tabel: Hamburgeri standard

  18. Big Mac arvestab raha ostujõudu / Harli Uljas

    Index Scriptorium Estoniae

    Uljas, Harli

    2005-01-01

    The Economist võrdleb maailma valuutade suhestamiseks Big Mac'i burgeri hindu 120 riigis, kuna see meetod võimaldab saada ülevaate riikide elanikkonna tegelikust ostujõust. Tabel: Hamburgeri standard

  19. MAC layer security issues in wireless mesh networks

    Science.gov (United States)

    Reddy, K. Ganesh; Thilagam, P. Santhi

    2016-03-01

    Wireless Mesh Networks (WMNs) have emerged as a promising technology for a broad range of applications due to their self-organizing, self-configuring and self-healing capability, in addition to their low cost and easy maintenance. Securing WMNs is more challenging and complex issue due to their inherent characteristics such as shared wireless medium, multi-hop and inter-network communication, highly dynamic network topology and decentralized architecture. These vulnerable features expose the WMNs to several types of attacks in MAC layer. The existing MAC layer standards and implementations are inadequate to secure these features and fail to provide comprehensive security solutions to protect both backbone and client mesh. Hence, there is a need for developing efficient, scalable and integrated security solutions for WMNs. In this paper, we classify the MAC layer attacks and analyze the existing countermeasures. Based on attacks classification and countermeasures analysis, we derive the research directions to enhance the MAC layer security for WMNs.

  20. Mac OS X : Tiger edition the missing manual

    CERN Document Server

    Pogue, David

    2005-01-01

    You can set your watch to it: As soon as Apple comes out with another version of Mac OS X, David Pogue hits the streets with another meticulous Missing Manual to cover it with a wealth of detail. The new Mac OS X 10.4, better known as Tiger, is faster than its predecessors, but nothing's too fast for Pogue and Mac OS X: The Missing Manual. There are many reasons why this is the most popular computer book of all time. With its hallmark objectivity, the Tiger Edition thoroughly explores the latest features to grace the Mac OS. Which ones work well and which do not? What should you look for? Th

  1. A tribute to Lloyd D. MacLean.

    Science.gov (United States)

    Keith, Roger G

    2015-08-01

    Dr. Lloyd D. MacLean, long-time co-editor of the Canadian Journal of Surgery passed away earlier this year at the age of 90. In order to appreciate the contributions of Dr. MacLean to the journal, this commentary recognizes him as a humble surgeon–scientist who was one of — if not the — most outstanding Canadian ambassadors to academic surgery in North America.

  2. Conformal holonomy in MacDowell-Mansouri gravity

    Energy Technology Data Exchange (ETDEWEB)

    Reid, James A., E-mail: j.a.reid@abdn.ac.uk [SUPA Department of Physics, University of Aberdeen, Aberdeen, AB24 3UE (United Kingdom); Wang, Charles H.-T., E-mail: c.wang@abdn.ac.uk [SUPA Department of Physics, University of Aberdeen, Aberdeen, AB24 3UE (United Kingdom); STFC Rutherford Appleton Laboratory, Chilton, Didcot, Oxon, OX11 0QX (United Kingdom)

    2014-03-15

    The MacDowell-Mansouri formulation of general relativity is based on a gauge theory whose gauge algebra depends on the sign of the cosmological constant. In this article, we show that the gauge algebra is uniquely determined by the conformal structure of spacetime itself. Specifically, we show that in vacuum: the spacetime conformal holonomy algebra coincides with the MacDowell-Mansouri gauge algebra for both signs of the cosmological constant, in both Lorentzian and Euclidean metric signatures.

  3. Some Problems of Alasdair MacIntyre’s "Emotivism Thesis"

    OpenAIRE

    2016-01-01

    In this article Alasdair MacIntyre’s thesis concerning emotivist use of moral utterances in contemporary liberal societies is analysed. One tries to show that it needs further clarification since at least three elements of MacIntyre’s argument seem to pose certain problems; these are: ‘discussion halt’ as the source of emotivism, comprehensive doctrines as premises of respective arguments in liberal debates and the problem of incommensurability. These three problematic eleme...

  4. Ad hoc mobile wireless networks principles, protocols, and applications

    CERN Document Server

    Sarkar, Subir Kumar

    2013-01-01

    The military, the research community, emergency services, and industrial environments all rely on ad hoc mobile wireless networks because of their simple infrastructure and minimal central administration. Now in its second edition, Ad Hoc Mobile Wireless Networks: Principles, Protocols, and Applications explains the concepts, mechanism, design, and performance of these highly valued systems. Following an overview of wireless network fundamentals, the book explores MAC layer, routing, multicast, and transport layer protocols for ad hoc mobile wireless networks. Next, it examines quality of serv

  5. 42 CFR 423.2102 - Request for MAC review when ALJ issues decision or dismissal.

    Science.gov (United States)

    2010-10-01

    ... 42 Public Health 3 2010-10-01 2010-10-01 false Request for MAC review when ALJ issues decision or... Reopening, ALJ Hearings, MAC review, and Judicial Review § 423.2102 Request for MAC review when ALJ issues decision or dismissal. (a)(1) An enrollee to the ALJ hearing may request a MAC review if the enrollee files...

  6. 42 CFR 423.2062 - Applicability of policies not binding on the ALJ and MAC.

    Science.gov (United States)

    2010-10-01

    ... and MAC. 423.2062 Section 423.2062 Public Health CENTERS FOR MEDICARE & MEDICAID SERVICES, DEPARTMENT... BENEFIT Reopening, ALJ Hearings, MAC review, and Judicial Review § 423.2062 Applicability of policies not binding on the ALJ and MAC. (a) ALJs and the MAC are not bound by CMS program guidance, such as program...

  7. 42 CFR 423.2110 - MAC reviews on its own motion.

    Science.gov (United States)

    2010-10-01

    ... 42 Public Health 3 2010-10-01 2010-10-01 false MAC reviews on its own motion. 423.2110 Section 423... (CONTINUED) MEDICARE PROGRAM VOLUNTARY MEDICARE PRESCRIPTION DRUG BENEFIT Reopening, ALJ Hearings, MAC review, and Judicial Review § 423.2110 MAC reviews on its own motion. (a) General rule. The MAC may decide on...

  8. 42 CFR 423.2050 - Removal of a hearing request from an ALJ to the MAC.

    Science.gov (United States)

    2010-10-01

    ... 42 Public Health 3 2010-10-01 2010-10-01 false Removal of a hearing request from an ALJ to the MAC..., ALJ Hearings, MAC review, and Judicial Review § 423.2050 Removal of a hearing request from an ALJ to the MAC. If a request for hearing is pending before an ALJ, the MAC may assume responsibility for...

  9. 42 CFR 423.2108 - MAC Actions when request for review is filed.

    Science.gov (United States)

    2010-10-01

    ... 42 Public Health 3 2010-10-01 2010-10-01 false MAC Actions when request for review is filed. 423... Hearings, MAC review, and Judicial Review § 423.2108 MAC Actions when request for review is filed. (a) General. Except as specified in paragraph (c) of this section, when an enrollee requests that the MAC...

  10. Anaesthesia with sevoflurane in pigeons: minimal anaesthetic concentration (MAC) determination and investigation of cardiorespiratory variables at 1 MAC.

    Science.gov (United States)

    Botman, J; Gabriel, F; Dugdale, A H A; Vandeweerd, J-M

    2016-05-28

    The objective of the study was to determine the minimal anaesthetic concentration (MAC) of sevoflurane (SEVO) in pigeons and investigate the effects of 1 MAC SEVO anaesthesia on cardiovascular and respiratory variables compared with the awake state. This is a prospective, experimental study. Animals were seven healthy adult pigeons. After acclimatisation to handling, heart rate (HR), heart rhythm, respiratory rate (fR), end-expired carbon dioxide tension (PE'CO2), inspired CO2 tension, indirect systolic arterial blood pressure (SAP) and cloacal temperature were measured to determine baseline, 'awake' values. Pigeons were then anaesthetised with SEVO and MAC was determined by the 'bracketing' method. The same variables were monitored during a 40 minute period at 1.0 MAC SEVO for each bird. Mean MAC was 3.0±0.6 per cent for SEVO. During maintenance of anaesthesia at 1.0 MAC, SAP decreased significantly (Pawake PE'CO2 values were unexpectedly low. Sinus arrhythmias were detected in two birds under SEVO anaesthesia. The times to tracheal intubation and to recovery were 2.5±0.7 and 6.4±1.7 minutes, respectively. Recovery was rapid and uneventful in all birds. In conclusion, SEVO is suitable for anaesthesia in pigeons. British Veterinary Association.

  11. Learning Unix for Mac OS X Tiger Unlock the Power of Unix

    CERN Document Server

    Taylor, Dave

    2005-01-01

    Thoroughly revised and updated for Mac OS X Tiger, this new edition introduces Mac users to the Terminal application and shows you how to navigate the command interface, explore hundreds of Unix applications that come with the Mac, and, most importantly, how to take advantage of both the Mac and Unix interfaces. If you want to master the command-line, this gentle guide to using Unix on Mac OS X Tiger is well worth its cover price

  12. 低占空比无线传感器网络同步 MAC 协议最优信标间隔分析%The Optimal Beacon Interval for Synchronous MAC in Low Duty-Cycle Wireless Sensor Networks

    Institute of Scientific and Technical Information of China (English)

    邢宇龙; 陈永锐; 易卫东; 段成华

    2016-01-01

    Energy efficiency is a fundamental theme in the design of wireless sensor networks protocols ,especially for medium access control (MAC) protocols .An energy‐efficient MAC protocol can significantly elongate the lifetime of wireless sensor networks by reducing the duty‐cycle of sensor nodes to an ultra‐low level .Synchronous MAC can be even more efficient in data transfer at the cost of requiring tight time synchronization through periodical beacon dissemination . The length of the beacon interval may greatly affect the energy efficiency of a synchronous MAC .A shorter beacon interval leads to higher synchronization cost due to frequent beacon sending and receiving ,while a longer beacon interval will lead to a larger guard time and longer idle listening due to clock drift . Therefore ,there is a tradeoff between these two parts of energy consumption .In this paper ,we investigate the optimal beacon interval for synchronous MAC in low duty‐cycle sensor networks ,and then present a strategy that adaptively utilizes the optimal beacon interval in a TDMA‐based MAC protocol (called Opt‐TDMA) .By configuring the beacon interval to its optimal value according to the data packets rate and network size ,Opt‐TDMA can reduce the overall power consumption of both sending/receiving beacons and data packets . Experimental results demonstrate that Opt‐TDMA is more energy‐efficient than pure TDMA protocol and SCP‐MAC by using optimal beacon interval and contention‐free transmission .%能量效率是无线传感器网络协议设计的首要考虑因素。无线传感器网络中,介质访问控制层(medium access control ,MAC)协议通过降低节点的占空比来降低网络能耗,延长网络的生命周期。相比其他 MAC 协议,尽管同步 MAC 需要周期性分发信标来保持严格的时间同步,但却在数据传输方面具有更高的能量效率。信标间隔的长短直接影响同步 M AC 能量效率的高低。一方面

  13. Collision Avoidance of Trains Using Arm7

    Directory of Open Access Journals (Sweden)

    Dr. K. R. R. Mohan Rao

    2015-11-01

    Full Text Available Railways are the popular mode of Transport in almost all major cities of the World. Railways are the most widely used and comfortable modes of transportation system. The major cause for railway accidents is collision of trains on the same track. The main aim of this anti collision system is to identify collision points and to report these error cases to main control room nearer to the station as well as grid control station. Majority of accidents occurred due to improper communication among the network between drivers and control room, due to wrong signaling, worst atmospheric condition, immediate change of route. The train driver doesn’t get proper information in time leading to hazardous situations. So this system by using zigbee protocol provides communication in between trains, which provide information or track id of one train to another train to avoid collision.

  14. 一种无线传感器网络异步MAC广播机制%A New Broadcast Mechanism of Asynchronous MAC for WSNs*

    Institute of Scientific and Technical Information of China (English)

    韩潇; 郭达伟; 刘航; 李现涛

    2011-01-01

    Asynchronous MAC protocols for Wireless Sensor Networks (WSN)are researched. PBMAC, a new broadcast MAC protocol with shorter preamble, is proposed based on the typical XMAC protocol. PBMAC acquires the sampling schedule by employing neighbor inform mechanism as well as improved preamble sequence. As a result, a shorter preamble is achieved. Evaluated by NS2 simulation, PBMAC is an idea protocol with high performance in terms of energy efficiency and delay compared with BMAC.%本文研究了基于竞争机制的无线传感器网络异步MAC协议,提出了一种新的基于XMAC的异步MAC广播机制--PBMAC(preamble broadcast MAC).PBMAC通过短的带有间隔的前导载波单元序列,结合邻居告知机制以及改进的前导载波单元获知邻居节点的采样时刻,有效地减小了前导载波长度.通过NS2仿真对BMAC和SPBMAC进行了比较和评估.实验结果表明,PBMAC不仅降低了源节点能耗,且减少了数据延迟.

  15. C-MAC compared with direct laryngoscopy for intubation in patients with cervical spine immobilization: A manikin trial.

    Science.gov (United States)

    Smereka, Jacek; Ladny, Jerzy R; Naylor, Amanda; Ruetzler, Kurt; Szarpak, Lukasz

    2017-08-01

    The aim of this study was to compare C-MAC videolaryngoscopy with direct laryngoscopy for intubation in simulated cervical spine immobilization conditions. The study was designed as a prospective randomized crossover manikin trial. 70 paramedics with MAC and C-MAC on the first attempt (95.7% MAC vs. 100% C-MAC), with similar intubation times (16.5s MAC vs. 18s C-MAC). Scenario B: The results with C-MAC were significantly better than those with MAC (pMAC vs. 19 s C-MAC), success of the first intubation attempt (88.6% MAC vs. 100% C-MAC), Cormack-Lehane grade, POGO score, severity of dental compression, device difficulty score, and preferred airway device. Scenario C: The results with C-MAC were significantly better than those with MAC (pMAC vs. 100% C-MAC), overall success rate, intubation time (27 s MAC vs. 20.5 s C-MAC), Cormack-Lehane grade, POGO score, dental compression, device difficulty score and the preferred airway device. The C-MAC videolaryngoscope is an excellent alternative to the MAC laryngoscope for intubating manikins with cervical spine immobilization. Copyright © 2017 Elsevier Inc. All rights reserved.

  16. MAC-Layer Active Dropping for Real-Time Video Streaming in 4G Access Networks

    KAUST Repository

    She, James

    2010-12-01

    This paper introduces a MAC-layer active dropping scheme to achieve effective resource utilization, which can satisfy the application-layer delay for real-time video streaming in time division multiple access based 4G broadband wireless access networks. When a video frame is not likely to be reconstructed within the application-layer delay bound at a receiver for the minimum decoding requirement, the MAC-layer protocol data units of such video frame will be proactively dropped before the transmission. An analytical model is developed to evaluate how confident a video frame can be delivered within its application-layer delay bound by jointly considering the effects of time-varying wireless channel, minimum decoding requirement of each video frame, data retransmission, and playback buffer. Extensive simulations with video traces are conducted to prove the effectiveness of the proposed scheme. When compared to conventional cross-layer schemes using prioritized-transmission/retransmission, the proposed scheme is practically implementable for more effective resource utilization, avoiding delay propagation, and achieving better video qualities under certain conditions.

  17. Victor Bérard et la Macédoine

    Directory of Open Access Journals (Sweden)

    Ivan Savev

    2011-01-01

    Full Text Available Un helléniste convaincu, Victor Bérard, en vient, au début du XXe siècle à soutenir l’existence de « Macédoniens » et le slogan « la Macédoine aux Macédoniens”.Le Congrès de Berlin en 1878 avait laissé la Macédoine aux mains des Ottomans. La Grèce, la Serbie et la Bulgarie, parvenues à ses limites et prévoyant le retrait futur des Ottomans peaufinent les arguments linguistiques et historiques qui justifieront leurs revendications territoriales. Victor Bérard, un helléniste respecté et bon connaisseur de la région sud balkanique, effectue des enquêtes en Macédoine en 1896 et 1903 qu’il publie à Paris.Cette étude montre comment, dans le contexte de la propagande nationaliste des prétendants à la possession de la Macédoine, Victor Bérard en vient progressivement à affirmer qu’il existe une population autochtone, les Macédoniens. Il soutient leur programme pour la constitution d’une fédération ou confédération avec le slogan « la Macédoine aux Macédoniens » ce qui fait toute l’actualité de ses ouvrages.In 1878, the Congress of Berlin had left Macedonia in the hands of the Ottomans. Greece, Serbia and Bulgaria had reached its limits. Anticipating the Ottoman retreat, they polish language and historical arguments that will justify their territorial claims. Victor Bérard, a respected Hellenist and a good expert of the southern Balkans, is doing researches in Macedonia in 1896 and 1903. These will be later published in Paris.This study shows how, in the context of the nationalist propaganda build-up made by the candidates for the possession of Macedonia, Victor Bérard comes progressively to assert the existence of a native population: the Macedonians. He supports their program for the forming of a federation or confederation which slogan would be “Macedonia to Macedonians”. This makes his works very topical.

  18. The many faces of Mac-1 in autoimmune disease.

    Science.gov (United States)

    Rosetti, Florencia; Mayadas, Tanya N

    2016-01-01

    Mac-1 (CD11b/CD18) is a β2 integrin classically regarded as a pro-inflammatory molecule because of its ability to promote phagocyte cytotoxic functions and enhance the function of several effector molecules such as FcγR, uPAR, and CD14. Nevertheless, recent reports have revealed that Mac-1 also plays significant immunoregulatory roles, and genetic variants in ITGAM, the gene that encodes CD11b, confer risk for the autoimmune disease systemic lupus erythematosus (SLE). This has renewed interest in the physiological roles of this integrin and raised new questions on how its seemingly opposing biological functions may be regulated. Here, we provide an overview of the CD18 integrins and how their activation may be regulated as this may shed light on how the opposing roles of Mac-1 may be elicited. We then discuss studies that exemplify Mac-1's pro-inflammatory versus regulatory roles particularly in the context of IgG immune complex-mediated inflammation. This includes a detailed examination of molecular mechanisms that could explain the risk-conferring effect of rs1143679, a single nucleotide non-synonymous Mac-1 polymorphism associated with SLE.

  19. Protocol to Exploit Waiting Resources for UASNs

    Directory of Open Access Journals (Sweden)

    Li-Ling Hung

    2016-03-01

    Full Text Available The transmission speed of acoustic waves in water is much slower than that of radio waves in terrestrial wireless sensor networks. Thus, the propagation delay in underwater acoustic sensor networks (UASN is much greater. Longer propagation delay leads to complicated communication and collision problems. To solve collision problems, some studies have proposed waiting mechanisms; however, long waiting mechanisms result in low bandwidth utilization. To improve throughput, this study proposes a slotted medium access control protocol to enhance bandwidth utilization in UASNs. The proposed mechanism increases communication by exploiting temporal and spatial resources that are typically idle in order to protect communication against interference. By reducing wait time, network performance and energy consumption can be improved. A performance evaluation demonstrates that when the data packets are large or sensor deployment is dense, the energy consumption of proposed protocol is less than that of existing protocols as well as the throughput is higher than that of existing protocols.

  20. Protocol to Exploit Waiting Resources for UASNs.

    Science.gov (United States)

    Hung, Li-Ling; Luo, Yung-Jeng

    2016-03-08

    The transmission speed of acoustic waves in water is much slower than that of radio waves in terrestrial wireless sensor networks. Thus, the propagation delay in underwater acoustic sensor networks (UASN) is much greater. Longer propagation delay leads to complicated communication and collision problems. To solve collision problems, some studies have proposed waiting mechanisms; however, long waiting mechanisms result in low bandwidth utilization. To improve throughput, this study proposes a slotted medium access control protocol to enhance bandwidth utilization in UASNs. The proposed mechanism increases communication by exploiting temporal and spatial resources that are typically idle in order to protect communication against interference. By reducing wait time, network performance and energy consumption can be improved. A performance evaluation demonstrates that when the data packets are large or sensor deployment is dense, the energy consumption of proposed protocol is less than that of existing protocols as well as the throughput is higher than that of existing protocols.