WorldWideScience

Sample records for backpressured packet networks

  1. Packet Tracer network simulator

    CERN Document Server

    Jesin, A

    2014-01-01

    A practical, fast-paced guide that gives you all the information you need to successfully create networks and simulate them using Packet Tracer.Packet Tracer Network Simulator is aimed at students, instructors, and network administrators who wish to use this simulator to learn how to perform networking instead of investing in expensive, specialized hardware. This book assumes that you have a good amount of Cisco networking knowledge, and it will focus more on Packet Tracer rather than networking.

  2. Optical packet switched networks

    DEFF Research Database (Denmark)

    Hansen, Peter Bukhave

    1999-01-01

    Optical packet switched networks are investigated with emphasis on the performance of the packet switch blocks. Initially, the network context of the optical packet switched network is described showing that a packet network will provide transparency, flexibility and bridge the granularity gap...... in interferometric wavelength converters is investigated showing that a 10 Gbit/s 19 4x4 swich blocks can be cascaded at a BER of 10-14. An analytical traffic model enables the calculation of the traffice performance of a WDM packet network. Hereby the importance of WDM and wavelegth conversion in the switch blocks...... is established as a flexible means to reduce the optical buffer, e.g., the number of fibre delay lines for a 16x16 switch block is reduced from 23 to 6 by going from 2 to 8 wavelength channels pr. inlet. Additionally, a component count analysis is carried out to illustrate the trade-offs in the switch block...

  3. Backpressure-based control protocols: design and computational aspects

    NARCIS (Netherlands)

    Miretskiy, D.I.; Scheinhardt, Willem R.W.; Mandjes, M.R.H.

    2009-01-01

    Congestion control in packet-based networks is often realized by feedback protocols. In this paper we assess their performance under a back-pressure mechanism that has been proposed and standardized for Ethernet metropolitan networks. In such a mechanism the service rate of an upstream queue is

  4. Backpressure-based control protocols: Design and computational aspects

    NARCIS (Netherlands)

    Miretskiy, D.I.; Scheinhardt, W.R.W.; Mandjes, M.R.H.

    2009-01-01

    Congestion control in packet-based networks is often realized by feedback protocols. In this paper we assess their performance under a back-pressure mechanism that has been proposed and standardized for Ethernet metropolitan networks. In such a mechanism the service rate of an upstream queue is

  5. Architectures of electro-optical packet switched networks

    DEFF Research Database (Denmark)

    Berger, Michael Stubert

    2004-01-01

    and examines possible architectures for future high capacity networks with high capacity nodes. It is assumed that optics will play a key role in this scenario, and in this respect, the European IST research project DAVID aimed at proposing viable architectures for optical packet switching, exploiting the best...... from optics and electronics. An overview of the DAVID network architecture is given, focusing on the MAN and WAN architecture as well as the MPLS based network hierarchy. A statistical model of the optical slot generation process is presented and utilised to evaluate delay vs. efficiency. Furthermore...... architecture for a buffered crossbar switch is presented. The architecture uses two levels of backpressure (flow control) with different constraints on round trip time. No additional scheduling complexity is introduced, and for the actual example shown, a reduction in memory of 75% was obtained at the cost...

  6. Internal Backpressure for Terabit Switch Fabrics

    DEFF Research Database (Denmark)

    Fagertun, Anna Manolova; Ruepp, Sarah Renée; Rytlig, Andreas

    2012-01-01

    This paper proposes and analyzes the efficiency of novel backpressure schemes for Terabit switch fabrics. The proposed schemes aim at buffer optimization under uniform traffic distribution with Bernoulli packet arrival process. Results show that a reduction of the needed maximum buffer capacity w...... with up to 47% can be achieved with switch-internal backpressure mechanisms at the expense of a small control overhead....

  7. Fair packet scheduling in Wireless Mesh Networks

    KAUST Repository

    Nawab, Faisal

    2014-02-01

    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 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 called Timestamp-ordered MAC (TMAC), aiming to alleviate the unfairness problem in WMNs. TMAC extends CSMA/CA by scheduling data packets based on their age. Prior to transmitting a data packet, a transmitter broadcasts a request control message appended with a timestamp to a selected list of neighbors. It can proceed with the transmission only if it receives a sufficient number of grant control messages from these neighbors. A grant message indicates that the associated data packet has the lowest timestamp of all the packets pending transmission at the local transmit queue. We demonstrate that a loose ordering of timestamps among neighboring nodes is sufficient for enforcing local fairness, subsequently leading to flow rate fairness in a multi-hop WMN. We show that TMAC can be implemented using the control frames in IEEE 802.11, and thus can be easily integrated in existing 802.11-based WMNs. Our simulation results show that TMAC achieves excellent resource allocation fairness while maintaining over 90% of maximum link capacity across a large number of topologies.

  8. A microcomputer for a packet switched network

    International Nuclear Information System (INIS)

    Seller, P.; Bairstow, R.; Barlow, J.; Waters, M.

    1982-12-01

    The Bubble Chamber Research Group of the Rutherford and Appleton Laboratory has a large film analysis facility. This comprises 16 digitising tables used for the measurement of bubble chamber film. Each of these tables has an associated microcomputer. These microcomputers are linked by a star structured packet switched local area network (LAN) to a VAX 11/780. The LAN, and in particular a microcomputer of novel architecture designed to act as the central switch of the network, is described. (author)

  9. Feasibility of Optical Packet Switched WDM Networks without Packet Synchronisation Under Bursty Traffic Conditions

    DEFF Research Database (Denmark)

    Fjelde, Tina; Hansen, Peter Bukhave; Kloch, Allan

    1999-01-01

    We show that complex packet synchronisation may be avoided in optical packetswitched networks. Detailed traffic analysis demonstrates that packet lossratios of 1e-10 are feasible under bursty traffic conditions for a highcapacity network consisting of asynchronously operated add-drop switch...

  10. Random linear network coding for streams with unequally sized packets

    DEFF Research Database (Denmark)

    Taghouti, Maroua; Roetter, Daniel Enrique Lucani; Pedersen, Morten Videbæk

    2016-01-01

    State of the art Random Linear Network Coding (RLNC) schemes assume that data streams generate packets with equal sizes. This is an assumption that results in the highest efficiency gains for RLNC. A typical solution for managing unequal packet sizes is to zero-pad the smallest packets. However, ...

  11. All-optical signal processing for optical packet switching networks

    NARCIS (Netherlands)

    Liu, Y.; Hill, M.T.; Calabretta, N.; Tangdiongga, E.; Geldenhuys, R.; Zhang, S.; Li, Z.; Waardt, de H.; Khoe, G.D.; Dorren, H.J.S.; Iftekharuddin, K.M.; awwal, A.A.S.

    2005-01-01

    We discuss how all-optical signal processing might play a role in future all-optical packet switched networks. We introduce a concept of optical packet switches that employ entirely all-optical signal processing technology. The optical packet switch is made out of three functional blocks: the

  12. Node design in optical packet switched networks

    DEFF Research Database (Denmark)

    Nord, Martin

    2006-01-01

    The thesis discusses motivation, realisation and performance of the Optical Packet Switching (OPS) network paradigm. The work includes proposals for designs and methods to efficiently use both the wavelength- and time domain for contention resolution in asynchronous operation. The project has also......S parameter. Finally, the thesis includes a proposal for a node design and associated MAC protocol for an OPS ring topology metropolitan area network with high throughput and fairness, also for unbalanced traffic....... proposed parallel designs to overcome scalability constraints and to support migration scenarios. Furthermore, it has proposed and demonstrated optical input processing schemes for hybrids networks to simultaneously support OPS and Optical Circuit Switching. Quality of Service (QoS) differentiation enables...

  13. Effects of packet retransmission with finite packet lifetime on traffic capacity in scale-free networks

    Science.gov (United States)

    Jiang, Zhong-Yuan; Ma, Jian-Feng

    Existing routing strategies such as the global dynamic routing [X. Ling, M. B. Hu, R. Jiang and Q. S. Wu, Phys. Rev. E 81, 016113 (2010)] can achieve very high traffic capacity at the cost of extremely long packet traveling delay. In many real complex networks, especially for real-time applications such as the instant communication software, extremely long packet traveling time is unacceptable. In this work, we propose to assign a finite Time-to-Live (TTL) parameter for each packet. To guarantee every packet to arrive at its destination within its TTL, we assume that a packet is retransmitted by its source once its TTL expires. We employ source routing mechanisms in the traffic model to avoid the routing-flaps induced by the global dynamic routing. We compose extensive simulations to verify our proposed mechanisms. With small TTL, the effects of packet retransmission on network traffic capacity are obvious, and the phase transition from flow free state to congested state occurs. For the purpose of reducing the computation frequency of the routing table, we employ a computing cycle Tc within which the routing table is recomputed once. The simulation results show that the traffic capacity decreases with increasing Tc. Our work provides a good insight into the understanding of effects of packet retransmission with finite packet lifetime on traffic capacity in scale-free networks.

  14. Development of optical packet and circuit integrated ring network testbed.

    Science.gov (United States)

    Furukawa, Hideaki; Harai, Hiroaki; Miyazawa, Takaya; Shinada, Satoshi; Kawasaki, Wataru; Wada, Naoya

    2011-12-12

    We developed novel integrated optical packet and circuit switch-node equipment. Compared with our previous equipment, a polarization-independent 4 × 4 semiconductor optical amplifier switch subsystem, gain-controlled optical amplifiers, and one 100 Gbps optical packet transponder and seven 10 Gbps optical path transponders with 10 Gigabit Ethernet (10GbE) client-interfaces were newly installed in the present system. The switch and amplifiers can provide more stable operation without equipment adjustments for the frequent polarization-rotations and dynamic packet-rate changes of optical packets. We constructed an optical packet and circuit integrated ring network testbed consisting of two switch nodes for accelerating network development, and we demonstrated 66 km fiber transmission and switching operation of multiplexed 14-wavelength 10 Gbps optical paths and 100 Gbps optical packets encapsulating 10GbE frames. Error-free (frame error rate optical packets of various packet lengths and packet rates, and stable operation of the network testbed was confirmed. In addition, 4K uncompressed video streaming over OPS links was successfully demonstrated. © 2011 Optical Society of America

  15. Performance evaluation of packet video transfer over local area networks

    OpenAIRE

    Lu, Jie

    1993-01-01

    This research investigates the implementation and performance of packet video transfer over local area networks. A network architecture is defined for packet video such that most of the processing is performed by the higher layers of the Open Systems Interconnection (OSI) reference model, while the lower layers provide real-time services. Implementation methods are discussed for coding schemes, including data compression, the network interface unit, and the underlying local are...

  16. Analysis of the packet formation process in packet-switched networks

    Science.gov (United States)

    Meditch, J. S.

    Two new queueing system models for the packet formation process in packet-switched telecommunication networks are developed, and their applications in process stability, performance analysis, and optimization studies are illustrated. The first, an M/M/1 queueing system characterization of the process, is a highly aggregated model which is useful for preliminary studies. The second, a marked extension of an earlier M/G/1 model, permits one to investigate stability, performance characteristics, and design of the packet formation process in terms of the details of processor architecture, and hardware and software implementations with processor structure and as many parameters as desired as variables. The two new models together with the earlier M/G/1 characterization span the spectrum of modeling complexity for the packet formation process from basic to advanced.

  17. Self-Management of Hybrid Optical and Packet Switching Networks

    NARCIS (Netherlands)

    Fioreze, Tiago; Pras, Aiko

    Hybrid optical and packet switching networks enable data to be forwarded at multiple levels. Large IP flows at the IP level may be therefore moved to the optical level bypassing the per hop routing decisions of the IP level. Such move could be beneficial since congested IP networks could be

  18. On the Effects of Heterogeneous Packet Lengths on Network Coding

    DEFF Research Database (Denmark)

    Compta, Pol Torres; Fitzek, Frank; Roetter, Daniel Enrique Lucani

    2014-01-01

    Random linear network coding (RLNC) has been shown to provide increased throughput, security and robustness for the transmission of data through the network. Most of the analysis and the demonstrators have focused on the study of data packets with the same size (number of bytes). This constitutes...

  19. Analysis Of Packets Delay In Wireless Data Networks

    Directory of Open Access Journals (Sweden)

    Krivchenkov Aleksandr

    2015-12-01

    Full Text Available The networks with wireless links for automation control applications traffic transmission when packets have small size and application payload is predictable are under consideration. Analytical model for packets delay on their propagation path through the network is proposed. Estimations for network architectures based on WiFi and Bluetooth wireless technologies are made. The specifications for physical layer 802.11 a/b/g/n and 802.15.1 are under consideration. Analytical and experimental results for delivered network bandwidth for different network architecture, traffic structure and wireless technologies were compared to validate that basic mechanisms are correctly taken into account in the model. It is shown that basic effects are taken into account and further accuracy “improvement” of the model will give not more than 5%. As a result that is important for automation control applications we have reliably received the lowest possible level for packets delay in one wireless link. For 802.11 it is of order of 0.2 ms, for 802.15.1 it is 1.25 ms and is true when application packet can be transferred by one data frame.

  20. The performance analysis of linux networking - packet receiving

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Wenji; Crawford, Matt; Bowden, Mark; /Fermilab

    2006-11-01

    The computing models for High-Energy Physics experiments are becoming ever more globally distributed and grid-based, both for technical reasons (e.g., to place computational and data resources near each other and the demand) and for strategic reasons (e.g., to leverage equipment investments). To support such computing models, the network and end systems, computing and storage, face unprecedented challenges. One of the biggest challenges is to transfer scientific data sets--now in the multi-petabyte (10{sup 15} bytes) range and expected to grow to exabytes within a decade--reliably and efficiently among facilities and computation centers scattered around the world. Both the network and end systems should be able to provide the capabilities to support high bandwidth, sustained, end-to-end data transmission. Recent trends in technology are showing that although the raw transmission speeds used in networks are increasing rapidly, the rate of advancement of microprocessor technology has slowed down. Therefore, network protocol-processing overheads have risen sharply in comparison with the time spent in packet transmission, resulting in degraded throughput for networked applications. More and more, it is the network end system, instead of the network, that is responsible for degraded performance of network applications. In this paper, the Linux system's packet receive process is studied from NIC to application. We develop a mathematical model to characterize the Linux packet receiving process. Key factors that affect Linux systems network performance are analyzed.

  1. Self-Management of Hybrid Optical and Packet Switching Networks

    NARCIS (Netherlands)

    Fioreze, Tiago

    2010-01-01

    Hybrid optical and packet switching networks are composed of multi-service hybrid devices that enable forwarding of data at multiple levels. Large IP flows at the IP level may be therefore moved to the optical level bypassing therefore the per hop routing decisions of the IP level. Such move could

  2. Application of Cellular Automata to Detection of Malicious Network Packets

    Science.gov (United States)

    Brown, Robert L.

    2014-01-01

    A problem in computer security is identification of attack signatures in network packets. An attack signature is a pattern of bits that characterizes a particular attack. Because there are many kinds of attacks, there are potentially many attack signatures. Furthermore, attackers may seek to avoid detection by altering the attack mechanism so that…

  3. Performance analysis of multi-hop wireless packet networks

    Directory of Open Access Journals (Sweden)

    Lim J.-T.

    1997-01-01

    Full Text Available In this paper, a unified analytical framework for performance analysis of multi-hop wireless packet networks is developed. The effect of coupling between the hops on the degradation of the delay-throughput characteristics and the probability of blocking is investigated. The issue of hop decoupling is addressed.

  4. Binary Systematic Network Coding for Progressive Packet Decoding

    OpenAIRE

    Jones, Andrew L.; Chatzigeorgiou, Ioannis; Tassi, Andrea

    2015-01-01

    We consider binary systematic network codes and investigate their capability of decoding a source message either in full or in part. We carry out a probability analysis, derive closed-form expressions for the decoding probability and show that systematic network coding outperforms conventional net- work coding. We also develop an algorithm based on Gaussian elimination that allows progressive decoding of source packets. Simulation results show that the proposed decoding algorithm can achieve ...

  5. Traffic analysis and signal processing in optical packet switched networks

    DEFF Research Database (Denmark)

    Fjelde, Tina

    2002-01-01

    /s optical packet switched network exploiting the best of optics and electronics, is used as a thread throughout the thesis. An overview of the DAVID network architecture is given, focussing on the MAN and WAN architecture as well as the MPLS-based network hierarchy. Subsequently, the traffic performance...... of the DAVID core optical packet router, which exploits wavelength conversion and fibre delay-line buffers for contention resolution, is analysed using a numerical model developed for that purpose. The robustness of the shared recirculating loop buffer with respect to´bursty traffic is demonstrated...... the injection of an additional clock signal into the IWC is presented. Results show very good transmission capabilities combined with a high-speed response. It is argued that signal regeneration is an inherent attribute of the IWC employed as a wavelength converter due to the sinusoidal transfer function...

  6. Opportunistic Nonorthogonal Packet Scheduling in Fixed Broadband Wireless Access Networks

    Directory of Open Access Journals (Sweden)

    Ahmed Mohamed H

    2006-01-01

    Full Text Available In order to mitigate high cochannel interference resulting from dense channel reuse, the interference management issues are often considered as essential part of scheduling schemes in fixed broadband wireless access (FBWA networks. To that end, a series of literature has been published recently, in which a group of base stations forms an interferer group (downlink transmissions from each base station become dominant interference for the users in other in-group base stations, and the scheduling scheme deployed in the group allows only one base station to transmit at a time. As a result of time orthogonality in transmissions, the dominant cochannel interferers are prevented, and hence the packet error rate can be improved. However, prohibiting concurrent transmissions in these orthogonal schemes introduces throughput penalty as well as higher end-to-end packet delay which might not be desirable for real-time services. In this paper, we utilize opportunistic nonorthogonality among the in-group transmissions whenever possible and propose a novel transmission scheduling scheme for FBWA networks. The proposed scheme, in contrast to the proactive interference avoidance techniques, strives for the improvements in delay and throughput efficiency. To facilitate opportunistic nonorthogonal transmissions in the interferer group, estimation of signal-to-interference-plus-noise ratio (SINR is required at the scheduler. We have observed from simulations that the proposed scheme outperforms the reference orthogonal scheme in terms of spectral efficiency, mean packet delay, and packet dropping rate.

  7. Performance Analysis and Optimization for Cognitive Radio Networks with Classified Secondary Users and Impatient Packets

    Directory of Open Access Journals (Sweden)

    Yuan Zhao

    2017-01-01

    Full Text Available A cognitive radio network with classified Secondary Users (SUs is considered. There are two types of SU packets, namely, SU1 packets and SU2 packets, in the system. The SU1 packets have higher priority than the SU2 packets. Considering the diversity of the SU packets and the real-time need of the interrupted SU packets, a novel spectrum allocation strategy with classified SUs and impatient packets is proposed. Based on the number of PU packets, SU1 packets, and SU2 packets in the system, by modeling the queue dynamics of the networks users as a three-dimensional discrete-time Markov chain, the transition probability matrix of the Markov chain is given. Then with the steady-state analysis, some important performance measures of the SU2 packets are derived to show the system performance with numerical results. Specially, in order to optimize the system actions of the SU2 packets, the individually optimal strategy and the socially optimal strategy for the SU2 packets are demonstrated. Finally, a pricing mechanism is provided to oblige the SU2 packets to follow the socially optimal strategy.

  8. Green partial packet recovery in wireless sensor networks

    KAUST Repository

    Daghistani, Anas

    2015-08-18

    Partial packet recovery is well known for increasing network throughput and reducing frame retransmissions. However, partial packet recovery methods in the literature are not energy-aware and hence they are not suitable for the battery powered wireless sensor motes. We propose Green-Frag, a novel adaptive partial packet recovery mechanism that is energy friendly. It can help prolonging the battery life of wireless sensor motes that are usually resource constrained. It dynamically partitions the frame into smaller blocks to avoid dropping the whole frame due to a single bit error. Also, Green-Frag is able to tolerate high interference and save energy by varying the transmit power based on channel quality and interference pattern. We experimentally evaluate the energy efficiency as well as goodput and delay of Green-Frag using our TelosB sensor mote testbed. We find that Green-Frag reduces energy consumption by 33% on average compared to the state of the art partial packet recovery scheme in the literature in the presence of Wi-Fi interference. In the worst case, this reduction in energy consumption comes at the cost of 10% reduction in goodput. Finally, Green-Frag reduces the latency by 22% on average compared to other static frame fragmentation schemes.

  9. IP- -: A Reduced Internet Protocol for Optical Packet Networking

    Science.gov (United States)

    Ohta, Masataka; Fujikawa, Kenji

    IP- - is proposed as an Internet Protocol suitable for optical packet networking. As optical routers require much faster control than electric ones and lack of optical buffers other than those by fiber delay lines requires fixed time control, Internet Protocols must be at least as simple as IPv4 and much simpler than IPv6. IP- - also addresses issues of IP address space exhaustion and IP routing table explosion.

  10. H-Infinity Control Design Considering Packet Loss as a Disturbance for Networked Control Systems

    OpenAIRE

    OGURA, Takashi; KOBAYASHI, Kentaro; OKADA, Hiraku; KATAYAMA, Masaaki

    2017-01-01

    This paper studies H∞ control for networked control systems with packet loss. In networked control systems, packet loss is one of major weakness because the control performance deteriorates due to packet loss. H∞ control, which is one of robust control, can design a controller to reduce the influence of disturbances acting on the controlled object. This paper proposes an H∞ control design that considers packet loss as a disturbance. Numerical examples show that the proposed H∞ control design ...

  11. A multi-ring optical packet and circuit integrated network with optical buffering.

    Science.gov (United States)

    Furukawa, Hideaki; Shinada, Satoshi; Miyazawa, Takaya; Harai, Hiroaki; Kawasaki, Wataru; Saito, Tatsuhiko; Matsunaga, Koji; Toyozumi, Tatuya; Wada, Naoya

    2012-12-17

    We newly developed a 3 × 3 integrated optical packet and circuit switch-node. Optical buffers and burst-mode erbium-doped fiber amplifiers with the gain flatness are installed in the 3 × 3 switch-node. The optical buffer can prevent packet collisions and decrease packet loss. We constructed a multi-ring optical packet and circuit integrated network testbed connecting two single-ring networks and a client network by the 3 × 3 switch-node. For the first time, we demonstrated 244 km fiber transmission and 5-node hopping of multiplexed 14-wavelength 10 Gbps optical paths and 100 Gbps optical packets encapsulating 10 Gigabit Ethernet frames on the testbed. Error-free (frame error rate optical packets of various packet lengths. In addition, successful avoidance of packet collisions by optical buffers was confirmed.

  12. Design and implementation considerations of a MSAT packet data network

    Science.gov (United States)

    Karam, Fouad G.; Hearn, Terry; Rohr, Doug; Guibord, Arthur F.

    1993-01-01

    The Mobile Data System, which is intended to provide for packet switched data services is currently under development. The system is based on a star network topology consisting of a centralized Data Hub (DH) serving a large number of mobile terminals. Through the Data Hub, end-to-end connections can be established between terrestrial users on public or private data networks and mobile users. The MDS network will be capable of offering a variety of services some of which are based on the standard X.25 network interface protocol, and others optimized for short messages and broadcast messages. A description of these services and the trade-offs in the DH design are presented.

  13. An adaptive routing strategy for packet delivery in complex networks

    International Nuclear Information System (INIS)

    Zhang, Huan; Liu, Zonghua; Tang, Ming; Hui, P.M.

    2007-01-01

    We present an efficient routing approach for delivering packets in complex networks. On delivering a message from a node to a destination, a node forwards the message to a neighbor by estimating the waiting time along the shortest path from each of its neighbors to the destination. This projected waiting time is dynamical in nature and the path through which a message is delivered would be adapted to the distribution of messages in the network. Implementing the approach on scale-free networks, we show that the present approach performs better than the shortest-path approach and another approach that takes into account of the waiting time only at the neighboring nodes. Key features in numerical results are explained by a mean field theory. The approach has the merit that messages are distributed among the nodes according to the capabilities of the nodes in handling messages

  14. Review of Rateless-Network-Coding-Based Packet Protection in Wireless Sensor Networks

    Directory of Open Access Journals (Sweden)

    A. S. Abdullah

    2015-01-01

    Full Text Available In recent times, there have been many developments in wireless sensor network (WSN technologies using coding theory. Fast and efficient protection schemes for data transfer over the WSN are some of the issues in coding theory. This paper reviews the issues related to the application of the joint rateless-network coding (RNC within the WSN in the context of packet protection. The RNC is a method in which any node in the network is allowed to encode and decode the transmitted data in order to construct a robust network, improve network throughput, and decrease delays. To the best of our knowledge, there has been no comprehensive discussion about RNC. To begin with, this paper briefly describes the concept of packet protection using network coding and rateless codes. We therefore discuss the applications of RNC for improving the capability of packet protection. Several works related to this issue are discussed. Finally, the paper concludes that the RNC-based packet protection scheme is able to improve the packet reception rate and suggests future studies to enhance the capability of RNC protection.

  15. High-speed packet switching network to link computers

    CERN Document Server

    Gerard, F M

    1980-01-01

    Virtually all of the experiments conducted at CERN use minicomputers today; some simply acquire data and store results on magnetic tape while others actually control experiments and help to process the resulting data. Currently there are more than two hundred minicomputers being used in the laboratory. In order to provide the minicomputer users with access to facilities available on mainframes and also to provide intercommunication between various experimental minicomputers, CERN opted for a packet switching network back in 1975. It was decided to use Modcomp II computers as switching nodes. The only software to be taken was a communications-oriented operating system called Maxcom. Today eight Modcomp II 16-bit computers plus six newer Classic minicomputers from Modular Computer Services have been purchased for the CERNET data communications networks. The current configuration comprises 11 nodes connecting more than 40 user machines to one another and to the laboratory's central computing facility. (0 refs).

  16. Hybrid Wavelength Routed and Optical Packet Switched Ring Networks for the Metropolitan Area Network

    DEFF Research Database (Denmark)

    Nord, Martin

    2005-01-01

    Increased data traffic in the metropolitan area network calls for new network architectures. This paper evaluates optical ring architectures based on optical packet switching, wavelength routing, and hybrid combinations of the two concepts. The evaluation includes overall throughput and fairness...... attractive when traffic is unbalanced....

  17. Novel Scheme for Packet Forwarding without Header Modifications in Optical Networks

    DEFF Research Database (Denmark)

    Wessing, Henrik; Christiansen, Henrik Lehrmann; Fjelde, Tina

    2002-01-01

    We present a novel scheme for packet forwarding in optical packet-switched networks and we further demonstrate its good scalability through simulations. The scheme requires neither header modification nor any label distribution protocol, thus reducing component cost while simplifying network...

  18. Network Layer Protocol Activation for Packet Data Access in UMTS WCDMA Laboratory Network

    OpenAIRE

    Lakkisto, Erkka

    2011-01-01

    The purpose of this Bachelor’s Thesis was to set up the UMTS WCDMA network in the laboratory environment of Helsinki Metropolia University of Applied Sciences and to study the network layer protocol activation for packet data access. The development of 3G technology has been very rapid and it can be considered as one of the main technologies in telecommunication. Implementing the laboratory network in Metropolia enables teaching and researching of the modern network technology. Labora...

  19. Dynamics of Number of Packets in Transit in Free Flow State of Data Network

    International Nuclear Information System (INIS)

    Shengkun Xie; Lawniczak, A.T.

    2011-01-01

    We study how the dynamics of Number of Packets in Transit (NPT) is affected by the coupling of a routing type with a volume of incoming packet traffic in a data network model of packet switching type. The NPT is a network performance indicator of an aggregate type that measures in '' real time '', how many packets are in the network on their routes to their destinations. We conduct our investigation using a time-discrete simulation model that is an abstraction of the Network Layer of the ISO OSI Seven Layer Reference Model. This model focuses on packets and their routing. We consider a static routing and two different types of dynamic routings coupled with different volumes of incoming packet traffic in the network free flow state. Our study shows that the order of the values of the NPT mean value time series depends on the coupling of a routing type with a volume of incoming packet traffic and changes when the volume of incoming packet traffic increases and is closed to the critical source load values, i.e. when it is closed to the phase transition points from the network free flow state to its congested states. (authors)

  20. Novel approach for all-optical packet switching in wide-area networks

    Science.gov (United States)

    Chlamtac, Imrich; Fumagalli, Andrea F.; Wedzinga, Gosse

    1998-09-01

    All-optical Wavelength Division Multiplexing (WDM) networks are believed to be a fundamental component in future high speed backbones. However, while wavelength routing made circuit switching in WDM feasible the reality of extant optical technology does not yet provide the necessary devices to achieve individual optical packet switching. This paper proposes to achieve all-optical packet switching in WDM Wide Area Networks (WANs) via a novel technique, called slot routing. Using slot routing, entire slots, each carrying multiple packets on distinct wavelengths, are switched transparently and individually. As a result packets can be optically transmitted and switched in the network using available fast and wavelength non-sensitive devices. The proposed routing technique leads to an optical packet switching solution, that is simple, practical, and unique as it makes it possible to build a WDM all-optical WAN with optical devices based on proven technologies.

  1. Dynamic optical fiber delivery of Ka-band packet transmissions for wireless access networks

    DEFF Research Database (Denmark)

    Rodríguez Páez, Juan Sebastián; Madsen, Peter; Tafur Monroy, Idelfonso

    2017-01-01

    A Reconfigurable Radio Access Unit is presented and experimentally demonstrated. In the unit, an optical switching system is set to dynamically deliver different packets to different points in the network. The packets are transmitted wirelesslty on the Ka-band (26–40 GHz), achieving BER values...

  2. Packetized Predictive Control for Rate-Limited Networks via Sparse Representation

    DEFF Research Database (Denmark)

    Nagahara, Masaaki; Quevedo, Daniel; Østergaard, Jan

    2012-01-01

    controller and the plant input. To achieve robustness with respect to dropouts, the controller transmits data packets containing plant input predictions, which minimize a finite horizon cost function. In our formulation, we design sparse packets for rate-limited networks, by adopting an an ℓ0 optimization...

  3. Synchronous Ethernet- Considerations and Implementation of the Packet Network Management Scheme

    Science.gov (United States)

    Gundale, A. S.; Aradhye, Ashwini

    2010-11-01

    Packet technologies were designed to work in asynchronous mode, where the oscillators in the equipment are free running. Although this allows the underlying infrastructure to operate, many applications exist that require frequency synchronization. Also, the ability to distribute synchronization from center to edge of network declines as infrastructure evolves toward a packet-based architecture. Synchronous Ethernet (SyncE) is a key development of the evolution of Ethernet into a carrier grade technology suitable for the WAN environment where frequency synchronization is required. The time of the day distribution in synchronized network at the physical layer enables many useful propositions in packet handling policies and other network management aspects.

  4. Packet throughput performance of multiservice, multirate OCDMA in elastic networks

    DEFF Research Database (Denmark)

    Raddo, Thiago R.; Sanches, Anderson L.; Tafur Monroy, Idelfonso

    2016-01-01

    the multiple-access interference (MAI) as binomially distributed. The packet throughput expression, by its turn, is derived considering a Poisson distribution for the composite packet arrivals. Numerical results show that the multicode technique is a good candidate for future multiservice, multirate OCDMA...

  5. Interception and modification of network authentication packets with the purpose of allowing alternative authentication modes

    Science.gov (United States)

    Kent, Alexander Dale [Los Alamos, NM

    2008-09-02

    Methods and systems in a data/computer network for authenticating identifying data transmitted from a client to a server through use of a gateway interface system which are communicately coupled to each other are disclosed. An authentication packet transmitted from a client to a server of the data network is intercepted by the interface, wherein the authentication packet is encrypted with a one-time password for transmission from the client to the server. The one-time password associated with the authentication packet can be verified utilizing a one-time password token system. The authentication packet can then be modified for acceptance by the server, wherein the response packet generated by the server is thereafter intercepted, verified and modified for transmission back to the client in a similar but reverse process.

  6. Throughput performance analysis of multirate, multiclass S-ALOHA OFFH-CDMA packet networks

    DEFF Research Database (Denmark)

    Raddo, Thiago R.; Sanches, Anderson L.; Borges, Ben Hur V

    2015-01-01

    In this paper, we propose a new throughput expression for multirate, multiclass slotted-ALOHA optical fast frequency hopping code-division multiple-access (OFFH-CDMA) packet networks considering a Poisson distribution for packet composite arrivals. We analyze the packet throughput performance...... of a three-class OFFH-CDMA network, where multirate transmissions are achieved via manipulation of the user's code parameters. It is shown that users transmitting at low rates interfere considerably in the performance of high rate users. Finally, we perform a validation procedure to demonstrate...

  7. 40 Gbit/s NRZ Packet-Length Insensitive Header Extraction for Optical Label Switching Networks

    DEFF Research Database (Denmark)

    Seoane, Jorge; Kehayas, E; Avramopoulos, H.

    2006-01-01

    A simple method for 40 Gbit/s NRZ header extraction based on envelope detection for optical label switching networks is presented. The scheme is insensitive to packet length and spacing and can be single-chip integrated cost-effectively......A simple method for 40 Gbit/s NRZ header extraction based on envelope detection for optical label switching networks is presented. The scheme is insensitive to packet length and spacing and can be single-chip integrated cost-effectively...

  8. Position-Based Packet Forwarding for Vehicular Ad-Hoc Networks

    OpenAIRE

    Füßler, Holger

    2007-01-01

    Mobile Ad-Hoc Networks, or MANETs, are data communication networks between (potentially) mobile computer systems equipped with wireless communication devices and — in their purest form — in complete absence of communication infrastructure. Usage scenarios for these systems include communication during disaster recovery or battlefield communications. One of the great research challenges concerning MANETs is the Packet Forwarding Problem, i.e., the question to which neighbor node a data packet ...

  9. Green partial packet recovery in wireless sensor networks

    KAUST Repository

    Daghistani, Anas; Ben Khalifa, Abderrahman; Showail, Ahmad; Shihada, Basem

    2015-01-01

    wireless sensor motes. We propose Green-Frag, a novel adaptive partial packet recovery mechanism that is energy friendly. It can help prolonging the battery life of wireless sensor motes that are usually resource constrained. It dynamically partitions

  10. Optical packet networks - conclusions from the IST DAVID project

    DEFF Research Database (Denmark)

    Dittmann, Lars

    2004-01-01

    This work outlines the result from the European research project DAVID working with optical packet switch solutions for both WAN and MAN. The project started July 2000 and has been completed successfully by the end of 2003.......This work outlines the result from the European research project DAVID working with optical packet switch solutions for both WAN and MAN. The project started July 2000 and has been completed successfully by the end of 2003....

  11. Source Authentication for Code Dissemination Supporting Dynamic Packet Size in Wireless Sensor Networks.

    Science.gov (United States)

    Kim, Daehee; Kim, Dongwan; An, Sunshin

    2016-07-09

    Code dissemination in wireless sensor networks (WSNs) is a procedure for distributing a new code image over the air in order to update programs. Due to the fact that WSNs are mostly deployed in unattended and hostile environments, secure code dissemination ensuring authenticity and integrity is essential. Recent works on dynamic packet size control in WSNs allow enhancing the energy efficiency of code dissemination by dynamically changing the packet size on the basis of link quality. However, the authentication tokens attached by the base station become useless in the next hop where the packet size can vary according to the link quality of the next hop. In this paper, we propose three source authentication schemes for code dissemination supporting dynamic packet size. Compared to traditional source authentication schemes such as μTESLA and digital signatures, our schemes provide secure source authentication under the environment, where the packet size changes in each hop, with smaller energy consumption.

  12. Source Authentication for Code Dissemination Supporting Dynamic Packet Size in Wireless Sensor Networks

    Science.gov (United States)

    Kim, Daehee; Kim, Dongwan; An, Sunshin

    2016-01-01

    Code dissemination in wireless sensor networks (WSNs) is a procedure for distributing a new code image over the air in order to update programs. Due to the fact that WSNs are mostly deployed in unattended and hostile environments, secure code dissemination ensuring authenticity and integrity is essential. Recent works on dynamic packet size control in WSNs allow enhancing the energy efficiency of code dissemination by dynamically changing the packet size on the basis of link quality. However, the authentication tokens attached by the base station become useless in the next hop where the packet size can vary according to the link quality of the next hop. In this paper, we propose three source authentication schemes for code dissemination supporting dynamic packet size. Compared to traditional source authentication schemes such as μTESLA and digital signatures, our schemes provide secure source authentication under the environment, where the packet size changes in each hop, with smaller energy consumption. PMID:27409616

  13. A Wave-guide Model for Packetized Media Streaming in Lossless Networks

    NARCIS (Netherlands)

    Konstantas, D.; Widya, I.A.

    2002-01-01

    Optimal operation of network based multimedia applications requires a precise specification of the network parameters. Different models have been used in the past in calculating the behavior of the network and defining parameters like throughput and delays of packets, using among others fluid

  14. Performance evaluation of a burst-mode EDFA in an optical packet and circuit integrated network.

    Science.gov (United States)

    Shiraiwa, Masaki; Awaji, Yoshinari; Furukawa, Hideaki; Shinada, Satoshi; Puttnam, Benjamin J; Wada, Naoya

    2013-12-30

    We experimentally investigate the performance of burst-mode EDFA in an optical packet and circuit integrated system. In such networks, packets and light paths can be dynamically assigned to the same fibers, resulting in gain transients in EDFAs throughout the network that can limit network performance. Here, we compare the performance of a 'burst-mode' EDFA (BM-EDFA), employing transient suppression techniques and optical feedback, with conventional EDFAs, and those using automatic gain control and previous BM-EDFA implementations. We first measure gain transients and other impairments in a simplified set-up before making frame error-rate measurements in a network demonstration.

  15. Adaptive sampling rate control for networked systems based on statistical characteristics of packet disordering.

    Science.gov (United States)

    Li, Jin-Na; Er, Meng-Joo; Tan, Yen-Kheng; Yu, Hai-Bin; Zeng, Peng

    2015-09-01

    This paper investigates an adaptive sampling rate control scheme for networked control systems (NCSs) subject to packet disordering. The main objectives of the proposed scheme are (a) to avoid heavy packet disordering existing in communication networks and (b) to stabilize NCSs with packet disordering, transmission delay and packet loss. First, a novel sampling rate control algorithm based on statistical characteristics of disordering entropy is proposed; secondly, an augmented closed-loop NCS that consists of a plant, a sampler and a state-feedback controller is transformed into an uncertain and stochastic system, which facilitates the controller design. Then, a sufficient condition for stochastic stability in terms of Linear Matrix Inequalities (LMIs) is given. Moreover, an adaptive tracking controller is designed such that the sampling period tracks a desired sampling period, which represents a significant contribution. Finally, experimental results are given to illustrate the effectiveness and advantages of the proposed scheme. Copyright © 2015 ISA. Published by Elsevier Ltd. All rights reserved.

  16. Analysis and implementation of packet preemption for Time Sensitive Networks

    DEFF Research Database (Denmark)

    Zhou, Zifan; Yan, Ying; Ruepp, Sarah Renée

    2017-01-01

    level simulation in Riverbed Modeler. The simulation is complemented by numerical analysis which provides the average queuing delay for both types of traffic (preemptable and express). Furthermore, the paper describes an approach to implement the packet preemption solution on an FPGA in VHDL, which...... illustrates the complexity of hardware implementation....

  17. A Scheduling Algorithm for Minimizing the Packet Error Probability in Clusterized TDMA Networks

    Directory of Open Access Journals (Sweden)

    Arash T. Toyserkani

    2009-01-01

    Full Text Available We consider clustered wireless networks, where transceivers in a cluster use a time-slotted mechanism (TDMA to access a wireless channel that is shared among several clusters. An approximate expression for the packet-loss probability is derived for networks with one or more mutually interfering clusters in Rayleigh fading environments, and the approximation is shown to be good for relevant scenarios. We then present a scheduling algorithm, based on Lagrangian duality, that exploits the derived packet-loss model in an attempt to minimize the average packet-loss probability in the network. Computer simulations of the proposed scheduling algorithm show that a significant increase in network throughput can be achieved compared to uncoordinated scheduling. Empirical trials also indicate that the proposed optimization algorithm almost always converges to an optimal schedule with a reasonable number of iterations. Thus, the proposed algorithm can also be used for bench-marking suboptimal scheduling algorithms.

  18. A Case Study of IPv6 Network Performance: Packet Delay, Loss, and Reordering

    Directory of Open Access Journals (Sweden)

    Fuliang Li

    2017-01-01

    Full Text Available Internet Protocol (IP is used to identify and locate computers on the Internet. Currently, IPv4 still routes most Internet traffic. However, with the exhausting of IPv4 addresses, the transition to IPv6 is imminent, because, as the successor of IPv4, IPv6 can provide a larger available address space. Existing studies have addressed the notion that IPv6-centric next generation networks are widely deployed and applied. In order to gain a deep understanding of IPv6, this paper revisits several critical IPv6 performance metrics. Our extensive measurement shows that packet delay and loss rate of IPv6 are similar to IPv4 when the AS-level paths are roughly the same. Specifically, when the link utilization exceeds a threshold, for example, 0.83 in our study, variation of packet delay presents a similar pattern with the variation of link utilization. If packet delay of a path is large, packet-loss rate of that path is more likely to fluctuate. In addition, we conduct a first-ever analysis of packet reordering in IPv6 world. Few IPv6 probe packets are out-of-order and the reordering rate is 2.3⁎10-6, which is much lower than that of 0.79% in IPv4 world. Our analysis consolidates an experimental basis for operators and researchers of IPv6 networks.

  19. Packets Distributing Evolutionary Algorithm Based on PSO for Ad Hoc Network

    Science.gov (United States)

    Xu, Xiao-Feng

    2018-03-01

    Wireless communication network has such features as limited bandwidth, changeful channel and dynamic topology, etc. Ad hoc network has lots of difficulties in accessing control, bandwidth distribution, resource assign and congestion control. Therefore, a wireless packets distributing Evolutionary algorithm based on PSO (DPSO)for Ad Hoc Network is proposed. Firstly, parameters impact on performance of network are analyzed and researched to obtain network performance effective function. Secondly, the improved PSO Evolutionary Algorithm is used to solve the optimization problem from local to global in the process of network packets distributing. The simulation results show that the algorithm can ensure fairness and timeliness of network transmission, as well as improve ad hoc network resource integrated utilization efficiency.

  20. The Optimization of the Data Packet Length in Adaptive Radio Networks

    Directory of Open Access Journals (Sweden)

    Anatolii P. Voiter

    2017-10-01

    Full Text Available Background. Development of methods and means of the adaptive management of the radio networks bandwidth with competitive access to the radio channel. Objective. The aim of the paper is to determine the packet length effect on the effective radio networks transmission rate with taking into account the parameters, formats, and procedures of the physical and link levels at using the MAC protocol with a rigid strategy of competitive access to the radio channel. Methods. The goal is achieved by creating and analyzing the mathematical model of the effective transmission rate in radio networks. The model is described by the equation for the effective transmission rate, which is the function of both the probability of the conflict-free transmission of the MAC protocol and the coefficient of the data packet size deviation from the optimal for LLC protocol. Results. It is proved that there is the optimal deviation of the data packet length for each MAC protocol traffic intensity value, which provides the most effective transfer rate. This makes the possibility for adaptive management of the radio bandwidth by applying a pre-calculated deviation of the data packet size in dependence on the traffic intensity. Conclusions. The proposed mathematical model is the tool for calculation of both the radio bandwidth network capacity and the optimal deviation of the data packet length at adaptive management of competitive access to a radio channel with a rigid strategy at conditions of the significant fluctuation in traffic intensity.

  1. Cybersecurity and Network Forensics: Analysis of Malicious Traffic towards a Honeynet with Deep Packet Inspection

    OpenAIRE

    Gabriel Arquelau Pimenta Rodrigues; Robson de Oliveira Albuquerque; Flávio Elias Gomes de Deus; Rafael Timóteo de Sousa Jr.; Gildásio Antônio de Oliveira Júnior; Luis Javier García Villalba; Tai-Hoon Kim

    2017-01-01

    Any network connected to the Internet is subject to cyber attacks. Strong security measures, forensic tools, and investigators contribute together to detect and mitigate those attacks, reducing the damages and enabling reestablishing the network to its normal operation, thus increasing the cybersecurity of the networked environment. This paper addresses the use of a forensic approach with Deep Packet Inspection to detect anomalies in the network traffic. As cyber attacks may occur on any laye...

  2. Moving the boundary between wavelength resources in optical packet and circuit integrated ring network.

    Science.gov (United States)

    Furukawa, Hideaki; Miyazawa, Takaya; Wada, Naoya; Harai, Hiroaki

    2014-01-13

    Optical packet and circuit integrated (OPCI) networks provide both optical packet switching (OPS) and optical circuit switching (OCS) links on the same physical infrastructure using a wavelength multiplexing technique in order to deal with best-effort services and quality-guaranteed services. To immediately respond to changes in user demand for OPS and OCS links, OPCI networks should dynamically adjust the amount of wavelength resources for each link. We propose a resource-adjustable hybrid optical packet/circuit switch and transponder. We also verify that distributed control of resource adjustments can be applied to the OPCI ring network testbed we developed. In cooperation with the resource adjustment mechanism and the hybrid switch and transponder, we demonstrate that automatically allocating a shared resource and moving the wavelength resource boundary between OPS and OCS links can be successfully executed, depending on the number of optical paths in use.

  3. Energy-saving scheme based on downstream packet scheduling in ethernet passive optical networks

    Science.gov (United States)

    Zhang, Lincong; Liu, Yejun; Guo, Lei; Gong, Xiaoxue

    2013-03-01

    With increasing network sizes, the energy consumption of Passive Optical Networks (PONs) has grown significantly. Therefore, it is important to design effective energy-saving schemes in PONs. Generally, energy-saving schemes have focused on sleeping the low-loaded Optical Network Units (ONUs), which tends to bring large packet delays. Further, the traditional ONU sleep modes are not capable of sleeping the transmitter and receiver independently, though they are not required to transmit or receive packets. Clearly, this approach contributes to wasted energy. Thus, in this paper, we propose an Energy-Saving scheme that is based on downstream Packet Scheduling (ESPS) in Ethernet PON (EPON). First, we design both an algorithm and a rule for downstream packet scheduling at the inter- and intra-ONU levels, respectively, to reduce the downstream packet delay. After that, we propose a hybrid sleep mode that contains not only ONU deep sleep mode but also independent sleep modes for the transmitter and the receiver. This ensures that the energy consumed by the ONUs is minimal. To realize the hybrid sleep mode, a modified GATE control message is designed that involves 10 time points for sleep processes. In ESPS, the 10 time points are calculated according to the allocated bandwidths in both the upstream and the downstream. The simulation results show that ESPS outperforms traditional Upstream Centric Scheduling (UCS) scheme in terms of energy consumption and the average delay for both real-time and non-real-time packets downstream. The simulation results also show that the average energy consumption of each ONU in larger-sized networks is less than that in smaller-sized networks; hence, our ESPS is better suited for larger-sized networks.

  4. Adaptive Control of the Packet Transmission Period with Solar Energy Harvesting Prediction in Wireless Sensor Networks

    Directory of Open Access Journals (Sweden)

    Kideok Kwon

    2015-04-01

    Full Text Available A number of research works has studied packet scheduling policies in energy scavenging wireless sensor networks, based on the predicted amount of harvested energy. Most of them aim to achieve energy neutrality, which means that an embedded system can operate perpetually while meeting application requirements. Unlike other renewable energy sources, solar energy has the feature of distinct periodicity in the amount of harvested energy over a day. Using this feature, this paper proposes a packet transmission control policy that can enhance the network performance while keeping sensor nodes alive. Furthermore, this paper suggests a novel solar energy prediction method that exploits the relation between cloudiness and solar radiation. The experimental results and analyses show that the proposed packet transmission policy outperforms others in terms of the deadline miss rate and data throughput. Furthermore, the proposed solar energy prediction method can predict more accurately than others by 6.92%.

  5. Adaptive control of the packet transmission period with solar energy harvesting prediction in wireless sensor networks.

    Science.gov (United States)

    Kwon, Kideok; Yang, Jihoon; Yoo, Younghwan

    2015-04-24

    A number of research works has studied packet scheduling policies in energy scavenging wireless sensor networks, based on the predicted amount of harvested energy. Most of them aim to achieve energy neutrality, which means that an embedded system can operate perpetually while meeting application requirements. Unlike other renewable energy sources, solar energy has the feature of distinct periodicity in the amount of harvested energy over a day. Using this feature, this paper proposes a packet transmission control policy that can enhance the network performance while keeping sensor nodes alive. Furthermore, this paper suggests a novel solar energy prediction method that exploits the relation between cloudiness and solar radiation. The experimental results and analyses show that the proposed packet transmission policy outperforms others in terms of the deadline miss rate and data throughput. Furthermore, the proposed solar energy prediction method can predict more accurately than others by 6.92%.

  6. Content-Adaptive Packetization and Streaming of Wavelet Video over IP Networks

    Directory of Open Access Journals (Sweden)

    Chien-Peng Ho

    2007-03-01

    Full Text Available This paper presents a framework of content-adaptive packetization scheme for streaming of 3D wavelet-based video content over lossy IP networks. The tradeoff between rate and distortion is controlled by jointly adapting scalable source coding rate and level of forward error correction (FEC protection. A content dependent packetization mechanism with data-interleaving and Reed-Solomon protection for wavelet-based video codecs is proposed to provide unequal error protection. This paper also tries to answer an important question for scalable video streaming systems: given extra bandwidth, should one increase the level of channel protection for the most important packets, or transmit more scalable source data? Experimental results show that the proposed framework achieves good balance between quality of the received video and level of error protection under bandwidth-varying lossy IP networks.

  7. Robust Controller for Delays and Packet Dropout Avoidance in Solar-Power Wireless Network

    OpenAIRE

    Al-Azzawi, Waleed

    2013-01-01

    Solar Wireless Networked Control Systems (SWNCS) are a style of distributed control systems where sensors, actuators, and controllers are interconnected via a wireless communication network. This system setup has the benefit of low cost, flexibility, low weight, no wiring and simplicity of system diagnoses and maintenance. However, it also unavoidably calls some wireless network time delays and packet dropout into the design procedure. Solar lighting system offers a clean environment, therefo...

  8. Quality of service in optical packet switched networks

    CERN Document Server

    Rahbar, Akbar G

    2015-01-01

    This book is a comprehensive study on OPS networks, its architectures, and developed techniques for improving its quality of switching and managing quality of service.  The book includes: Introduction to OPS networks, OOFDM networks, GMPLS-enabled optical networks, QoS in OPS networks Hybrid contention avoidance/resolution schemes in both long-haul and metro optical networks Hybrid optical switching schemes

  9. Synchronization challenges in packet-based Cloud-RAN fronthaul for mobile networks

    DEFF Research Database (Denmark)

    Checko, Aleksandra; Juul, Anders Christian; Christiansen, Henrik Lehrmann

    2015-01-01

    In this paper, we look at reusing existing packet-based network (e.g. Ethernet) to possibly decrease deployment costs of fronthaul Cloud Radio Access Network (C-RAN) network and cost of Baseband Unit (BBU) resources. The challenge of this solution is that it requires mobile traffic (until now...... transmitted over synchronous protocols) to traverse the asynchronous Ethernet without losing synchronization. We analyze synchronization requirements of mobile networks and present an overview of solutions that fulfill them in traditional mobile networks. Then we elaborate on challenges that packet-based...... fronthaul imposes. We analyze possible contributions to frequency and phase error. We verify the feasibility of using the IEEE 1588v2 also know as Precision Time Protocol (PTP) for providing accurate phase and frequency synchronization. The study is based on simulations made in OPNET modeler. Thereby we...

  10. Improved algorithms for circuit fault diagnosis based on wavelet packet and neural network

    International Nuclear Information System (INIS)

    Zhang, W-Q; Xu, C

    2008-01-01

    In this paper, two improved BP neural network algorithms of fault diagnosis for analog circuit are presented through using optimal wavelet packet transform(OWPT) or incomplete wavelet packet transform(IWPT) as preprocessor. The purpose of preprocessing is to reduce the nodes in input layer and hidden layer of BP neural network, so that the neural network gains faster training and convergence speed. At first, we apply OWPT or IWPT to the response signal of circuit under test(CUT), and then calculate the normalization energy of each frequency band. The normalization energy is used to train the BP neural network to diagnose faulty components in the analog circuit. These two algorithms need small network size, while have faster learning and convergence speed. Finally, simulation results illustrate the two algorithms are effective for fault diagnosis

  11. Host based internet protocol (IP) packet analysis to enhance network security

    International Nuclear Information System (INIS)

    Ahmad, T.; Ahmad, S.Z.; Yasin, M.M.

    2007-01-01

    Data communication in a computer network environment is facing serious security threats from numerous sources such as viruses, worms, Zombies etc. These threats can be broadly characterized as internal or external security threats. Internal threats are mainly attributed to sneaker-nets, utility modems and unauthorized users, which can be minimized by skillful network administration, password management and optimum usage policy definition. The external threats need more serious attention as these attacks are mostly coming from public networks such as Internet. Frequency and complexity of such attacks is much higher as compared to internal attacks. This paper presents a host based network layer screening of external and internal IP packets for logging, analyzing and real-time detection of possible IP spoofing and Denial of Service attacks. This work can also be used in tuning security rules definition for gateway firewalls. Software has been developed which intercepts IP traffic and analyses it with respect to integrity and origin of I P packet. The received IP packets are parsed and analyzed for possible signs of intrusion. The results show that by watching and categorizing composition of various transport protocol such as TCP, UDP, ICMP and others along with verifying the origin of received IP packet can help in devising real-time firewall rule and blocking possible external attack. This is highly desirable for fighting against zero day attacks and can result in a better Mean Time between Failures (MTBF) to increase the survivability of computer network. Used in a right context, packet screening and filtering can be a useful tool for provision of reliable and stable network services. (author)

  12. Packets distribution in a tree-based topology wireless sensor networks

    CSIR Research Space (South Africa)

    Akpakwu, GA

    2016-07-01

    Full Text Available The concept of data distribution within cluster of sensor nodes to the source sink has resulted to intense research in Wireless Sensor Networks (WSNs). In this paper, in order to determine the scheduling length of packet distribution, a tree...

  13. InP monolithically integrated label swapper device for spectral amplitude coded optical packet networks

    NARCIS (Netherlands)

    Muñoz, P.; García-Olcina, R.; Doménech, J.D.; Rius, M.; Sancho, J.C.; Capmany, J.; Chen, L.R.; Habib, C.; Leijtens, X.J.M.; Vries, de T.; Heck, M.J.R.; Augustin, L.M.; Nötzel, R.; Robbins, D.J.

    2010-01-01

    In this paper a label swapping device, for spectral amplitude coded optical packet networks, fully integrated using InP technology is presented. Compared to previous demonstrations using discrete component assembly, the device footprint is reduced by a factor of 105 and the operation speed is

  14. Event-Driven Control for Networked Control Systems With Quantization and Markov Packet Losses.

    Science.gov (United States)

    Yang, Hongjiu; Xu, Yang; Zhang, Jinhui

    2016-05-23

    In this paper, event-driven is used in a networked control system (NCS) which is subjected to the effect of quantization and packet losses. A discrete event-detector is used to monitor specific events in the NCS. Both an arbitrary region quantizer and Markov jump packet losses are also considered for the NCS. Based on zoom strategy and Lyapunov theory, a complete proof is given to guarantee mean square stability of the closed-loop system. Stabilization of the NCS is ensured by designing a feedback controller. Lastly, an inverted pendulum model is given to show the advantages and effectiveness of the proposed results.

  15. Dynamic Output Feedback Control for Nonlinear Networked Control Systems with Random Packet Dropout and Random Delay

    Directory of Open Access Journals (Sweden)

    Shuiqing Yu

    2013-01-01

    Full Text Available This paper investigates the dynamic output feedback control for nonlinear networked control systems with both random packet dropout and random delay. Random packet dropout and random delay are modeled as two independent random variables. An observer-based dynamic output feedback controller is designed based upon the Lyapunov theory. The quantitative relationship of the dropout rate, transition probability matrix, and nonlinear level is derived by solving a set of linear matrix inequalities. Finally, an example is presented to illustrate the effectiveness of the proposed method.

  16. Towards Effective Trust-Based Packet Filtering in Collaborative Network Environments

    DEFF Research Database (Denmark)

    Meng, Weizhi; Li, Wenjuan; Kwok, Lam-For

    2017-01-01

    compromised by insider attacks. In this paper, we adopt the existing CIDN framework and aim to apply a collaborative trust-based approach to reduce unwanted packets. More specifically, we develop a collaborative trust-based packet filter, which can be deployed in collaborative networks and be robust against...... typical insider attacks (e.g., betrayal attacks). Experimental results in various simulated and practical environments demonstrate that our filter can perform effectively in reducing unwanted traffic and can defend against insider attacks through identifying malicious nodes in a quick manner, as compared...

  17. Cybersecurity and Network Forensics: Analysis of Malicious Traffic towards a Honeynet with Deep Packet Inspection

    Directory of Open Access Journals (Sweden)

    Gabriel Arquelau Pimenta Rodrigues

    2017-10-01

    Full Text Available Any network connected to the Internet is subject to cyber attacks. Strong security measures, forensic tools, and investigators contribute together to detect and mitigate those attacks, reducing the damages and enabling reestablishing the network to its normal operation, thus increasing the cybersecurity of the networked environment. This paper addresses the use of a forensic approach with Deep Packet Inspection to detect anomalies in the network traffic. As cyber attacks may occur on any layer of the TCP/IP networking model, Deep Packet Inspection is an effective way to reveal suspicious content in the headers or the payloads in any packet processing layer, excepting of course situations where the payload is encrypted. Although being efficient, this technique still faces big challenges. The contributions of this paper rely on the association of Deep Packet Inspection with forensics analysis to evaluate different attacks towards a Honeynet operating in a network laboratory at the University of Brasilia. In this perspective, this work could identify and map the content and behavior of attacks such as the Mirai botnet and brute-force attacks targeting various different network services. Obtained results demonstrate the behavior of automated attacks (such as worms and bots and non-automated attacks (brute-force conducted with different tools. The data collected and analyzed is then used to generate statistics of used usernames and passwords, IP and services distribution, among other elements. This paper also discusses the importance of network forensics and Chain of Custody procedures to conduct investigations and shows the effectiveness of the mentioned techniques in evaluating different attacks in networks.

  18. Forwarding Techniques for IP Fragmented Packets in a Real 6LoWPAN Network

    Directory of Open Access Journals (Sweden)

    Jordi Casademont

    2011-01-01

    Full Text Available Wireless Sensor Networks (WSNs are attracting more and more interest since they offer a low-cost solution to the problem of providing a means to deploy large sensor networks in a number of application domains. We believe that a crucial aspect to facilitate WSN diffusion is to make them interoperable with external IP networks. This can be achieved by using the 6LoWPAN protocol stack. 6LoWPAN enables the transmission of IPv6 packets over WSNs based on the IEEE 802.15.4 standard. IPv6 packet size is considerably larger than that of IEEE 802.15.4 data frame. To overcome this problem, 6LoWPAN introduces an adaptation layer between the network and data link layers, allowing IPv6 packets to be adapted to the lower layer constraints. This adaptation layer provides fragmentation and header compression of IP packets. Furthermore, it also can be involved in routing decisions. Depending on which layer is responsible for routing decisions, 6LoWPAN divides routing in two categories: mesh under if the layer concerned is the adaptation layer and route over if it is the network layer. In this paper we analyze different routing solutions (route over, mesh under and enhanced route over focusing on how they forward fragments. We evaluate their performance in terms of latency and energy consumption when transmitting IP fragmented packets. All the tests have been performed in a real 6LoWPAN implementation. After consideration of the main problems in forwarding of mesh frames in WSN, we propose and analyze a new alternative scheme based on mesh under, which we call controlled mesh under.

  19. Forwarding techniques for IP fragmented packets in a real 6LoWPAN network.

    Science.gov (United States)

    Ludovici, Alessandro; Calveras, Anna; Casademont, Jordi

    2011-01-01

    Wireless Sensor Networks (WSNs) are attracting more and more interest since they offer a low-cost solution to the problem of providing a means to deploy large sensor networks in a number of application domains. We believe that a crucial aspect to facilitate WSN diffusion is to make them interoperable with external IP networks. This can be achieved by using the 6LoWPAN protocol stack. 6LoWPAN enables the transmission of IPv6 packets over WSNs based on the IEEE 802.15.4 standard. IPv6 packet size is considerably larger than that of IEEE 802.15.4 data frame. To overcome this problem, 6LoWPAN introduces an adaptation layer between the network and data link layers, allowing IPv6 packets to be adapted to the lower layer constraints. This adaptation layer provides fragmentation and header compression of IP packets. Furthermore, it also can be involved in routing decisions. Depending on which layer is responsible for routing decisions, 6LoWPAN divides routing in two categories: mesh under if the layer concerned is the adaptation layer and route over if it is the network layer. In this paper we analyze different routing solutions (route over, mesh under and enhanced route over) focusing on how they forward fragments. We evaluate their performance in terms of latency and energy consumption when transmitting IP fragmented packets. All the tests have been performed in a real 6LoWPAN implementation. After consideration of the main problems in forwarding of mesh frames in WSN, we propose and analyze a new alternative scheme based on mesh under, which we call controlled mesh under.

  20. Packet Duplication in Dual Connectivity Enabled 5G Wireless Networks: Overview and Challenges

    OpenAIRE

    Aijaz, Adnan

    2018-01-01

    Enabling ultra-reliable low latency communications (uRLLC) over 5G wireless networks creates challenging design requirements, particularly on the air-interface. The stringent latency and reliability targets require enhancements at different layers of the protocol stack. On the other hand, the parallel redundancy protocol (PRP), wherein each data packet is duplicated and transmitted concurrently over two independent networks, provides a simple solution for improving reliability and reducing la...

  1. Stabilization of a Wireless Networked Control System with Packet Loss and Time Delay: An ADS Approach

    Directory of Open Access Journals (Sweden)

    Jing Wang

    2012-01-01

    Full Text Available The stabilization problem of a wireless networked control system is considered in this paper. Both time delay and packet loss exist simultaneously in the wireless network. The system is modeled as an asynchronous dynamic system (ADS with unstable subsystems. A sufficient condition for the system to be stable is presented. A numerical example is given to demonstrate the effectiveness of the proposed approach.

  2. A Performance Analysis for UMTS Packet Switched Network Based on Multivariate KPIS

    OpenAIRE

    Ouyang, Ye; Fallah, M. Hosein

    2010-01-01

    Mobile data services are penetrating mobile markets rapidly. The mobile industry relies heavily on data service to replace the traditional voice services with the evolution of the wireless technology and market. A reliable packet service network is critical to the mobile operators to maintain their core competence in data service market. Furthermore, mobile operators need to develop effective operational models to manage the varying mix of voice, data and video traffic on a single network. Ap...

  3. Novel scheme for efficient and cost-effective forwarding of packets in optical networks without header modification

    DEFF Research Database (Denmark)

    Wessing, Henrik; Fjelde, Tina; Christiansen, Henrik Lehrmann

    2001-01-01

    We present a novel scheme for addressing the outputs in optical packet switches and demonstrate its good scalability. The scheme requires neither header modification nor distribution of routing information to the packet switches, thus reducing optical component count while simplifying network...

  4. Buffer Management and Hybrid Probability Choice Routing for Packet Delivery in Opportunistic Networks

    Directory of Open Access Journals (Sweden)

    Daru Pan

    2012-01-01

    Full Text Available Due to the features of long connection delays, frequent network partitions, and topology unsteadiness, the design of opportunistic networks faces the challenge of how to effectively deliver data based only on occasional encountering of nodes, where the conventional routing schemes do not work properly. This paper proposes a hybrid probability choice routing protocol with buffer management for opportunistic networks. A delivery probability function is set up based on continuous encounter duration time, which is used for selecting a better node to relay packets. By combining the buffer management utility and the delivery probability, a total utility is used to decide whether the packet should be kept in the buffer or be directly transmitted to the encountering node. Simulation results show that the proposed routing outperforms the existing one in terms of the delivery rate and the average delay.

  5. Intelligent Packet Shaper to Avoid Network Congestion for Improved Streaming Video Quality at Clients

    DEFF Research Database (Denmark)

    Kaul, Manohar; Khosla, Rajiv; Mitsukura, Y

    2003-01-01

    of this intelligent traffic-shaping algorithm on the underlying network real time packet traffic and the eradication of unwanted abruption in the streaming video qualiy. This paper concluded from the end results of the simulation that neural networks are a very superior means of modeling real-time traffic......This paper proposes a traffic shaping algorithm based on neural networks, which adapts to a network over which streaming video is being transmitted. The purpose of this intelligent shaper is to eradicate all traffic congestion and improve the end-user's video quality. It possesses the capability...

  6. Evaluation of Packet Preemption over C-RAN Fronthaul Networks

    DEFF Research Database (Denmark)

    Yan, Ying; Zhou, Zifan; Ruepp, Sarah Renée

    2017-01-01

    The Cloud Radio Access Network (C-RAN) is viewed as a new solution with benefits of reduced cost by sharing resources. This is achieved by the separation of the radio part and the radio processing part, where the transport network between them is referred to as front-haul. It is essential to meet...

  7. 40-Gbps optical backbone network deep packet inspection based on FPGA

    Science.gov (United States)

    Zuo, Yuan; Huang, Zhiping; Su, Shaojing

    2014-11-01

    In the era of information, the big data, which contains huge information, brings about some problems, such as high speed transmission, storage and real-time analysis and process. As the important media for data transmission, the Internet is the significant part for big data processing research. With the large-scale usage of the Internet, the data streaming of network is increasing rapidly. The speed level in the main fiber optic communication of the present has reached 40Gbps, even 100Gbps, therefore data on the optical backbone network shows some features of massive data. Generally, data services are provided via IP packets on the optical backbone network, which is constituted with SDH (Synchronous Digital Hierarchy). Hence this method that IP packets are directly mapped into SDH payload is named POS (Packet over SDH) technology. Aiming at the problems of real time process of high speed massive data, this paper designs a process system platform based on ATCA for 40Gbps POS signal data stream recognition and packet content capture, which employs the FPGA as the CPU. This platform offers pre-processing of clustering algorithms, service traffic identification and data mining for the following big data storage and analysis with high efficiency. Also, the operational procedure is proposed in this paper. Four channels of 10Gbps POS signal decomposed by the analysis module, which chooses FPGA as the kernel, are inputted to the flow classification module and the pattern matching component based on TCAM. Based on the properties of the length of payload and net flows, buffer management is added to the platform to keep the key flow information. According to data stream analysis, DPI (deep packet inspection) and flow balance distribute, the signal is transmitted to the backend machine through the giga Ethernet ports on back board. Practice shows that the proposed platform is superior to the traditional applications based on ASIC and NP.

  8. CERNET - A high-speed packet-switching network

    International Nuclear Information System (INIS)

    Gerard, J.M.

    1981-01-01

    A general mesh-structured high-speed computer network has been designed and built. This network provides communication between any pair of connected user computers over distances of upto 6 km and at line speeds of 1 to 5 Mbit/second. The network is composed of a communication subnet providing a datagram service, complemented by tasks in the connected machines to implement an end-to-end logical link protocol. Details are given of the overall structure as well as the specific modules of which the system is composed. (orig.)

  9. Enhancing a network coding security scheme to avoid packet dropping in wireless mesh networks / H.L.H.C. Terblanche.

    OpenAIRE

    Terblanche, Heila Levina Helena Catharina

    2013-01-01

    With the increase of mobile and smart device usage, the interest in dynamically forming networks is rising. One such type of network isWireless Mesh Networks (WMNs). WMNs are multi-hop networks, with a decentralised nature that can dynamically form into mesh topologies. Network Coding (NC) is a method that is used to increase the efficiency of networks by encoding and decoding data on packet level by means of an XOR operation. NC works well with WMNs because it can exploit WMNs broadcast a...

  10. Time-optimum packet scheduling for many-to-one routing in wireless sensor networks

    Science.gov (United States)

    Song, W.-Z.; Yuan, F.; LaHusen, R.; Shirazi, B.

    2007-01-01

    This paper studies the wireless sensor networks (WSN) application scenario with periodical traffic from all sensors to a sink. We present a time-optimum and energy-efficient packet scheduling algorithm and its distributed implementation. We first give a general many-to-one packet scheduling algorithm for wireless networks, and then prove that it is time-optimum and costs [image omitted], N(u0)-1) time slots, assuming each node reports one unit of data in each round. Here [image omitted] is the total number of sensors, while [image omitted] denotes the number of sensors in a sink's largest branch subtree. With a few adjustments, we then show that our algorithm also achieves time-optimum scheduling in heterogeneous scenarios, where each sensor reports a heterogeneous amount of data in each round. Then we give a distributed implementation to let each node calculate its duty-cycle locally and maximize efficiency globally. In this packet-scheduling algorithm, each node goes to sleep whenever it is not transceiving, so that the energy waste of idle listening is also mitigated. Finally, simulations are conducted to evaluate network performance using the Qualnet simulator. Among other contributions, our study also identifies the maximum reporting frequency that a deployed sensor network can handle.

  11. Optimal design of mixed-media packet-switching networks - Routing and capacity assignment

    Science.gov (United States)

    Huynh, D.; Kuo, F. F.; Kobayashi, H.

    1977-01-01

    This paper considers a mixed-media packet-switched computer communication network which consists of a low-delay terrestrial store-and-forward subnet combined with a low-cost high-bandwidth satellite subnet. We show how to route traffic via ground and/or satellite links by means of static, deterministic procedures and assign capacities to channels subject to a given linear cost such that the network average delay is minimized. Two operational schemes for this network model are investigated: one is a scheme in which the satellite channel is used as a slotted ALOHA channel; the other is a new multiaccess scheme we propose in which whenever a channel collision occurs, retransmission of the involved packets will route through ground links to their destinations. The performance of both schemes is evaluated and compared in terms of cost and average packet delay tradeoffs for some examples. The results offer guidelines for the design and optimal utilization of mixed-media networks.

  12. Adaptable System Increasing the Transmission Speed and Reliability in Packet Network by Optimizing Delay

    Directory of Open Access Journals (Sweden)

    Zbynek Kocur

    2014-01-01

    Full Text Available There is a great diversity in the transmission technologies in current data networks. Individual technologies are in most cases incompatible at physical and partially also at the link layer of the reference ISO/OSI model. Network compatibility, as the ability to transmit data, is realizable through the third layer, which is able to guarantee the operation of the different devices across their technological differences. The proposed inverse packet multiplexer addresses increase of the speed and reliability of packet transmission to the third layer, and at the same time it increases the stability of the data communication by the regulation of the delay value during the transmission. This article presents implementation of a communication system and its verification in real conditions. The conclusion compares the strengths and weaknesses of the proposed control system.

  13. Analysing efficiency of IPv6 packet transmission over 6LoWPAN network

    Science.gov (United States)

    Kozłowski, Adam; Sosnowski, Janusz

    2017-08-01

    Practical proliferation of Internet of Things (IoT) concept depends upon communication efficiency in the related network. In the paper we outline basic features of wireless communication protocols used in IoT and concentrate on analysing communication overheads. In particular, we discuss the impact of IPv6 packet length on 6LoWPAN network operation with physical and MAC layer defined by IEEE 802.15.4 standard. The presented analysis methodology is useful in estimation of the total goodput (throughput at the application level) and energy consumptions within the whole traffic model which are the crucial features of IoT networks.

  14. Limiting Energy Consumption by Decreasing Packets Retransmissions in 5G Network

    Directory of Open Access Journals (Sweden)

    Łukasz Apiecionek

    2017-01-01

    Full Text Available This article presents the potential of using Multipath Transmission Control Protocol for limiting the energy consumption in 5G network. The number of errors occurring during packet transmissions and in effect the number of retransmissions affect the consumption of energy by the devices in the network. The paper analyzes the potential energy savings from implementing an algorithm for detecting problems and predicting the future retransmissions. Although this is the main object of the paper, it must be emphasized that the proposed method also allows increasing the speed of transmission and improving the security of the data and it is easy to implement in 5G networks.

  15. On the Packet Loss Correlation in Wireless Mesh Networks

    DEFF Research Database (Denmark)

    Pahlevani, Peyman; Cabrera Guerrero, Juan Alberto; Roetter, Daniel Enrique Lucani

    2014-01-01

    /or multi-path routing approaches as well as network coding (NC) subgraph selection problems (routing in NC). This paper proposes simple channel models to incorporate the effect of correlation between receivers in a parametric fashion and supports them with a measurement campaign that leverages various...

  16. Impulsive Controller Design for Complex Nonlinear Singular Networked Systems with Packet Dropouts

    Directory of Open Access Journals (Sweden)

    Xian-Lin Zhao

    2013-01-01

    Full Text Available Globally exponential stability of Complex (with coupling Nonlinear Singular Impulsive Networked Control Systems (CNSINCS with packet dropouts and time-delay is investigated. Firstly, the mathematic model of CNSINCS is established. Then, by employing the method of Lyapunov functional, exponential stability criteria are obtained and the impulsive controller design method is given. Finally, some simulation results are provided to demonstrate the effectiveness of the proposed method.

  17. Monitor Network Traffic with Packet Capture (pcap) on an Android Device

    Science.gov (United States)

    2015-09-01

    administrative privileges . Under the current design Android development requirement, an Android Graphical User Interface (GUI) application cannot directly...build an Android application to monitor network traffic using open source packet capture (pcap) libraries. 15. SUBJECT TERMS ELIDe, Android , pcap 16...Building Application with Native Codes 5 8.1 Calling Native Codes Using JNI 5 8.2 Calling Native Codes from an Android Application 8 9. Retrieve Live

  18. A Novel Approach to Detect Network Attacks Using G-HMM-Based Temporal Relations between Internet Protocol Packets

    Directory of Open Access Journals (Sweden)

    Han Kyusuk

    2011-01-01

    Full Text Available This paper introduces novel attack detection approaches on mobile and wireless device security and network which consider temporal relations between internet packets. In this paper we first present a field selection technique using a Genetic Algorithm and generate a Packet-based Mining Association Rule from an original Mining Association Rule for Support Vector Machine in mobile and wireless network environment. Through the preprocessing with PMAR, SVM inputs can account for time variation between packets in mobile and wireless network. Third, we present Gaussian observation Hidden Markov Model to exploit the hidden relationships between packets based on probabilistic estimation. In our G-HMM approach, we also apply G-HMM feature reduction for better initialization. We demonstrate the usefulness of our SVM and G-HMM approaches with GA on MIT Lincoln Lab datasets and a live dataset that we captured on a real mobile and wireless network. Moreover, experimental results are verified by -fold cross-validation test.

  19. QoS Differentiated and Fair Packet Scheduling in Broadband Wireless Access Networks

    Directory of Open Access Journals (Sweden)

    Zhang Yan

    2009-01-01

    Full Text Available This paper studies the packet scheduling problem in Broadband Wireless Access (BWA networks. The key difficulties of the BWA scheduling problem lie in the high variability of wireless channel capacity and the unknown model of packet arrival process. It is difficult for traditional heuristic scheduling algorithms to handle the situation and guarantee satisfying performance in BWA networks. In this paper, we introduce learning-based approach for a better solution. Specifically, we formulate the packet scheduling problem as an average cost Semi-Markov Decision Process (SMDP. Then, we solve the SMDP by using reinforcement learning. A feature-based linear approximation and the Temporal-Difference learning technique are employed to produce a near optimal solution of the corresponding SMDP problem. The proposed algorithm, called Reinforcement Learning Scheduling (RLS, has in-built capability of self-training. It is able to adaptively and timely regulate its scheduling policy according to the instantaneous network conditions. Simulation results indicate that RLS outperforms two classical scheduling algorithms and simultaneously considers: (i effective QoS differentiation, (ii high bandwidth utilization, and (iii both short-term and long-term fairness.

  20. An Adaptive Power Efficient Packet Scheduling Algorithm for Wimax Networks

    OpenAIRE

    R Murali Prasad; P. Satish Kumar

    2010-01-01

    Admission control schemes and scheduling algorithms are designed to offer QoS services in 802.16/802.16e networks and a number of studies have investigated these issues. But the channel condition and priority of traffic classes are very rarely considered in the existing scheduling algorithms. Although a number of energy saving mechanisms have been proposed for the IEEE 802.16e, to minimize the power consumption of IEEE 802.16e mobile stations with multiple real-time connections has not yet be...

  1. A packet-based dual-rate PID control strategy for a slow-rate sensing Networked Control System.

    Science.gov (United States)

    Cuenca, A; Alcaina, J; Salt, J; Casanova, V; Pizá, R

    2018-05-01

    This paper introduces a packet-based dual-rate control strategy to face time-varying network-induced delays, packet dropouts and packet disorder in a Networked Control System. Slow-rate sensing enables to achieve energy saving and to avoid packet disorder. Fast-rate actuation makes reaching the desired control performance possible. The dual-rate PID controller is split into two parts: a slow-rate PI controller located at the remote side (with no permanent communication to the plant) and a fast-rate PD controller located at the local side. The remote side also includes a prediction stage in order to generate the packet of future, estimated slow-rate control actions. These actions are sent to the local side and converted to fast-rate ones to be used when a packet does not arrive at this side due to the network-induced delay or due to occurring dropouts. The proposed control solution is able to approximately reach the nominal (no-delay, no-dropout) performance despite the existence of time-varying delays and packet dropouts. Control system stability is ensured in terms of probabilistic Linear Matrix Inequalities (LMIs). Via real-time control for a Cartesian robot, results clearly reveal the superiority of the control solution compared to a previous proposal by authors. Copyright © 2018 ISA. Published by Elsevier Ltd. All rights reserved.

  2. Power Minimization through Packet Retention in Cognitive Radio Sensor Networks under Interference and Delay Constraints: An Optimal Stopping Approach

    Directory of Open Access Journals (Sweden)

    Amr Y. Elnakeeb

    2016-04-01

    Full Text Available The aim of this article is twofold: First, we study the problem of packets retention in a queue with the aim of minimizing transmission power in delay-tolerant applications. The problem is classified as an optimal stopping problem. The optimal stopping rule has been derived as well. Optimal number of released packets is determined in each round through an Integer Linear Programming (ILP optimization problem. This transmission paradigm is tested via simulations in an interference-free environment leading to a significant reduction in transmission power (at least 55%. Second, we address the problem of applying the scheme of packets retention through the Optimal Stopping Policy (OSP to underlay Cognitive Radio Sensor Networks (CRSNs where strict interference threshold does exist. Simulations proved that our scheme outperforms traditional transmission method as far as dropped packet rate and Average Power per Transmitted Packet (APTP are concerned.

  3. An On-Demand Emergency Packet Transmission Scheme for Wireless Body Area Networks.

    Science.gov (United States)

    Al Ameen, Moshaddique; Hong, Choong Seon

    2015-12-04

    The rapid developments of sensor devices that can actively monitor human activities have given rise to a new field called wireless body area network (BAN). A BAN can manage devices in, on and around the human body. Major requirements of such a network are energy efficiency, long lifetime, low delay, security, etc. Traffic in a BAN can be scheduled (normal) or event-driven (emergency). Traditional media access control (MAC) protocols use duty cycling to improve performance. A sleep-wake up cycle is employed to save energy. However, this mechanism lacks features to handle emergency traffic in a prompt and immediate manner. To deliver an emergency packet, a node has to wait until the receiver is awake. It also suffers from overheads, such as idle listening, overhearing and control packet handshakes. An external radio-triggered wake up mechanism is proposed to handle prompt communication. It can reduce the overheads and improve the performance through an on-demand scheme. In this work, we present a simple-to-implement on-demand packet transmission scheme by taking into considerations the requirements of a BAN. The major concern is handling the event-based emergency traffic. The performance analysis of the proposed scheme is presented. The results showed significant improvements in the overall performance of a BAN compared to state-of-the-art protocols in terms of energy consumption, delay and lifetime.

  4. An Intrinsic Encoding of a Subset of C and its Application to TLS Network Packet Processing

    Directory of Open Access Journals (Sweden)

    Reynald Affeldt

    2014-09-01

    Full Text Available TLS is such a widespread security protocol that errors in its implementation can have disastrous consequences. This responsibility is mostly borne by programmers, caught between specifications with the ambiguities of natural language and error-prone low-level parsing of network packets. We report here on the construction in the Coq proof-assistant of libraries to model, specify, and verify C programs to process TLS packets. We provide in particular an encoding of the core subset of C whose originality lies in its use of dependent types to guarantee statically well-formedness of datatypes and correct typing. We further equip this encoding with a Separation logic that enables byte-level reasoning and also provide a logical view of data structures. We also formalize a significant part of the RFC for TLS, again using dependent types to capture succinctly constraints that are left implicit in the prose document. Finally, we apply the above framework to an existing implementation of TLS (namely, PolarSSL of which we specify and verify a parsing function for network packets. Thanks to this experiment, we were able to spot ambiguities in the RFC and to correct bugs in the C source code.

  5. An On-Demand Emergency Packet Transmission Scheme for Wireless Body Area Networks

    Directory of Open Access Journals (Sweden)

    Moshaddique Al Ameen

    2015-12-01

    Full Text Available The rapid developments of sensor devices that can actively monitor human activities have given rise to a new field called wireless body area network (BAN. A BAN can manage devices in, on and around the human body. Major requirements of such a network are energy efficiency, long lifetime, low delay, security, etc. Traffic in a BAN can be scheduled (normal or event-driven (emergency. Traditional media access control (MAC protocols use duty cycling to improve performance. A sleep-wake up cycle is employed to save energy. However, this mechanism lacks features to handle emergency traffic in a prompt and immediate manner. To deliver an emergency packet, a node has to wait until the receiver is awake. It also suffers from overheads, such as idle listening, overhearing and control packet handshakes. An external radio-triggered wake up mechanism is proposed to handle prompt communication. It can reduce the overheads and improve the performance through an on-demand scheme. In this work, we present a simple-to-implement on-demand packet transmission scheme by taking into considerations the requirements of a BAN. The major concern is handling the event-based emergency traffic. The performance analysis of the proposed scheme is presented. The results showed significant improvements in the overall performance of a BAN compared to state-of-the-art protocols in terms of energy consumption, delay and lifetime.

  6. Smart home design for electronic devices monitoring based wireless gateway network using cisco packet tracer

    Science.gov (United States)

    Sihombing, Oloan; Zendrato, Niskarto; Laia, Yonata; Nababan, Marlince; Sitanggang, Delima; Purba, Windania; Batubara, Diarmansyah; Aisyah, Siti; Indra, Evta; Siregar, Saut

    2018-04-01

    In the era of technological development today, the technology has become the need for the life of today's society. One is needed to create a smart home in turning on and off electronic devices via smartphone. So far in turning off and turning the home electronic device is done by pressing the switch or remote button, so in control of electronic device control less effective. The home smart design is done by simulation concept by testing system, network configuration, and wireless home gateway computer network equipment required by a smart home network on cisco packet tracer using Internet Thing (IoT) control. In testing the IoT home network wireless network gateway system, multiple electronic devices can be controlled and monitored via smartphone based on predefined configuration conditions. With the Smart Ho me can potentially increase energy efficiency, decrease energy usage costs, control electronics and change the role of residents.

  7. Optimum back-pressure forging using servo die cushion

    OpenAIRE

    Kawamoto, Kiichiro; Yoneyama, Takeshi; Okada, Masato; Kitayama, Satoshi; Chikahisa, Junpei

    2014-01-01

    This study focused on utilizing a servo die cushion (in conjunction with a servo press) as a "back-pressure load generator," to determine its effect on shape accuracy of the formed part and total forming load in forward extrusion during cold forging. The effect of back-pressure load application was confirmed in experiments, and the optimum setting pattern of back-pressure load was considered to minimize both shape accuracy of the formed part and back-pressure energy, which was representative ...

  8. Adaptive Conflict-Free Optimization of Rule Sets for Network Security Packet Filtering Devices

    Directory of Open Access Journals (Sweden)

    Andrea Baiocchi

    2015-01-01

    Full Text Available Packet filtering and processing rules management in firewalls and security gateways has become commonplace in increasingly complex networks. On one side there is a need to maintain the logic of high level policies, which requires administrators to implement and update a large amount of filtering rules while keeping them conflict-free, that is, avoiding security inconsistencies. On the other side, traffic adaptive optimization of large rule lists is useful for general purpose computers used as filtering devices, without specific designed hardware, to face growing link speeds and to harden filtering devices against DoS and DDoS attacks. Our work joins the two issues in an innovative way and defines a traffic adaptive algorithm to find conflict-free optimized rule sets, by relying on information gathered with traffic logs. The proposed approach suits current technology architectures and exploits available features, like traffic log databases, to minimize the impact of ACO development on the packet filtering devices. We demonstrate the benefit entailed by the proposed algorithm through measurements on a test bed made up of real-life, commercial packet filtering devices.

  9. An efficient multi-carrier position-based packet forwarding protocol for wireless sensor networks

    KAUST Repository

    Bader, Ahmed

    2012-01-01

    Beaconless position-based forwarding protocols have recently evolved as a promising solution for packet forwarding in wireless sensor networks. However, as the node density grows, the overhead incurred in the process of relay selection grows significantly. As such, end-to-end performance in terms of energy and latency is adversely impacted. With the motivation of developing a packet forwarding mechanism that is tolerant to variation in node density, an alternative position-based protocol is proposed in this paper. In contrast to existing beaconless protocols, the proposed protocol is designed such that it eliminates the need for potential relays to undergo a relay selection process. Rather, any eligible relay may decide to forward the packet ahead, thus significantly reducing the underlying overhead. The operation of the proposed protocol is empowered by exploiting favorable features of orthogonal frequency division multiplexing (OFDM) at the physical layer. The end-to-end performance of the proposed protocol is evaluated against existing beaconless position-based protocols analytically and as well by means of simulations. The proposed protocol is demonstrated in this paper to be more efficient. In particular, it is shown that for the same amount of energy the proposed protocol transports one bit from source to destination much quicker. © 2012 IEEE.

  10. Monitoring Agent for Detecting Malicious Packet Drops for Wireless Sensor Networks in the Microgrid and Grid-Enabled Vehicles

    Directory of Open Access Journals (Sweden)

    Jongbin Ko

    2012-05-01

    Full Text Available Of the range of wireless communication technologies, wireless sensor networks (WSN will be one of the most appropriate technologies for the Microgrid and Grid-enabled Vehicles in the Smartgrid. To ensure the security of WSN, the detection of attacks is more efficient than their prevention because of the lack of computing power. Malicious packet drops are the easiest means of attacking WSNs. Thus, the sensors used for constructing a WSN require a packet drop monitoring agent, such as Watchdog. However, Watchdog has a partial drop problem such that an attacker can manipulate the packet dropping rate below the minimum misbehaviour monitoring threshold. Furthermore, Watchdog does not consider real traffic situations, such as congestion and collision, and so it has no way of recognizing whether a packet drop is due to a real attack or network congestion. In this paper, we propose a malicious packet drop monitoring agent, which considers traffic conditions. We used the actual traffic volume on neighbouring nodes and the drop rate while monitoring a sending node for specific period. It is more effective in real network scenarios because unlike Watchdog it considers the actual traffic, which only uses the Pathrater. Moreover, our proposed method does not require authentication, packet encryption or detection packets. Thus, there is a lower likelihood of detection failure due to packet spoofing, Man-In-the Middle attacks or Wormhole attacks. To test the suitability of our proposed concept for a series of network scenarios, we divided the simulations into three types: one attack node, more than one attack nodes and no attack nodes. The results of the simulations meet our expectations.

  11. Packet reversed packet combining scheme

    International Nuclear Information System (INIS)

    Bhunia, C.T.

    2006-07-01

    The packet combining scheme is a well defined simple error correction scheme with erroneous copies at the receiver. It offers higher throughput combined with ARQ protocols in networks than that of basic ARQ protocols. But packet combining scheme fails to correct errors when the errors occur in the same bit locations of two erroneous copies. In the present work, we propose a scheme that will correct error if the errors occur at the same bit location of the erroneous copies. The proposed scheme when combined with ARQ protocol will offer higher throughput. (author)

  12. Networked Estimation for Event-Based Sampling Systems with Packet Dropouts

    Directory of Open Access Journals (Sweden)

    Young Soo Suh

    2009-04-01

    Full Text Available This paper is concerned with a networked estimation problem in which sensor data are transmitted over the network. In the event-based sampling scheme known as level-crossing or send-on-delta (SOD, sensor data are transmitted to the estimator node if the difference between the current sensor value and the last transmitted one is greater than a given threshold. Event-based sampling has been shown to be more efficient than the time-triggered one in some situations, especially in network bandwidth improvement. However, it cannot detect packet dropout situations because data transmission and reception do not use a periodical time-stamp mechanism as found in time-triggered sampling systems. Motivated by this issue, we propose a modified event-based sampling scheme called modified SOD in which sensor data are sent when either the change of sensor output exceeds a given threshold or the time elapses more than a given interval. Through simulation results, we show that the proposed modified SOD sampling significantly improves estimation performance when packet dropouts happen.

  13. Highly Efficient Multi Channel Packet Forwarding with Round Robin Intermittent Periodic Transmit for Multihop Wireless Backhaul Networks

    Science.gov (United States)

    Furukawa, Hiroshi

    2017-01-01

    Round Robin based Intermittent Periodic Transmit (RR-IPT) has been proposed which achieves highly efficient multi-hop relays in multi-hop wireless backhaul networks (MWBN) where relay nodes are 2-dimensionally deployed. This paper newly investigates multi-channel packet scheduling and forwarding scheme for RR-IPT. Downlink traffic is forwarded by RR-IPT via one of the channels, while uplink traffic and part of downlink are accommodated in the other channel. By comparing IPT and carrier sense multiple access with collision avoidance (CSMA/CA) for uplink/downlink packet forwarding channel, IPT is more effective in reducing packet loss rate whereas CSMA/CA is better in terms of system throughput and packet delay improvement. PMID:29137164

  14. Utilization of OFDM for efficient packet forwarding in wireless sensor networks

    KAUST Repository

    Bader, Ahmed

    2011-12-01

    Beaconless position-based forwarding protocols have recently evolved as a promising solution for packet forwarding in wireless sensor networks. However, as the network density grows, the overhead incurred grows significantly. As such, end-to-end energy and delay performance is adversely impacted. Motivated by the need for a forwarding mechanism that is more tolerant to growth in node density, an alternative position-based protocol is proposed in this paper. The protocol is designed such that it completely eliminates the need for potential relays to undergo a relay election process. Rather, any eligible relay may decide to forward the packet ahead, thus significantly reducing the overhead. The operation of the proposed protocol is empowered by exploiting favorable features of orthogonal frequency division multiplexing (OFDM) at the physical layer. End-to-end performance is evaluated here against existing beaconless protocols. It is demonstrated that the proposed protocol is more efficient since it is able to offer lower end-to-end delay for the same amount of energy consumption. © 2011 IEEE.

  15. On the Coded Packet Relay Network in the Presence of Neighbors

    DEFF Research Database (Denmark)

    Khamfroush, Hana; Pahlevani, Peyman; Roetter, Daniel Enrique Lucani

    2014-01-01

    This paper studies the problem of optimal use of a relay for reducing the transmission time of data packets from a source to a destination using network coding. More importantly, we address an effect that is typically overlooked in previous studies: the presence of active transmitting nodes...... in the neighborhood of such devices, which is typical in wireless mesh networks. We show that in systems with a fair medium access control mechanism (MAC), the use of a relay in a crowded medium brings forth considerable and unforeseen improvements, including up to 3.5x gains in terms of throughput compared to using...... only the direct link in some of our examples, and a considerable extension of the operating region where using a relay is beneficial. The problem is formulated as a Markov Decision Process (MDP) and numerical results are provided comparing simple, close–to–optimal heuristics to the optimal scheme....

  16. Improved Robust Stability Criterion of Networked Control Systems with Transmission Delays and Packet Loss

    Directory of Open Access Journals (Sweden)

    Shenping Xiao

    2014-01-01

    Full Text Available The problem of stability analysis for a class of networked control systems (NCSs with network-induced delay and packet dropout is investigated in this paper. Based on the working mechanism of zero-order holder, the closed-loop NCS is modeled as a continuous-time linear system with input delay. By introducing a novel Lyapunov-Krasovskii functional which splits both the lower and upper bounds of the delay into two subintervals, respectively, and utilizes reciprocally convex combination technique, a new stability criterion is derived in terms of linear matrix inequalities. Compared with previous results in the literature, the obtained stability criterion is less conservative. Numerical examples demonstrate the validity and feasibility of the proposed method.

  17. An Enhanced Feedback-Base Downlink Packet Scheduling Algorithm for Mobile TV in WIMAX Networks

    Directory of Open Access Journals (Sweden)

    Joseph Oyewale

    2013-06-01

    Full Text Available With high speed access network technology like WIMAX, there is the need for efficient management of radio resources where the throughput and Qos requirements for Multicasting Broadcasting Services (MBS for example TV are to be met. An enhanced  feedback-base downlink Packet scheduling algorithm  that can be used in IEEE 802.16d/e networks for mobile TV “one way traffic”(MBS is needed to support many users utilizing multiuser diversity of the  broadband of WIMAX systems where a group of users(good/worst channels share allocated resources (bandwidth. This paper proposes a WIMAX framework feedback-base (like a channel-awareness downlink packet scheduling algorithm for Mobile TV traffics in IEEE806.16, in which network Physical Timing Slots (PSs resource blocks are allocated in a dynamic way to mobile TV subscribers based on the Channel State information (CSI feedback, and then considering users with worst channels with the aim of improving system throughput while system coverage is being guaranteed. The algorithm was examined by changing the PSs bandwidth allocation of the users and different number of users of a cell. Simulation results show our proposed algorithm performed better than other algorithms (blind algorithms in terms of improvement in system throughput performance. /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin:0cm; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso

  18. Modified weighted fair queuing for packet scheduling in mobile WiMAX networks

    Science.gov (United States)

    Satrya, Gandeva B.; Brotoharsono, Tri

    2013-03-01

    The increase of user mobility and the need for data access anytime also increases the interest in broadband wireless access (BWA). The best available quality of experience for mobile data service users are assured for IEEE 802.16e based users. The main problem of assuring a high QOS value is how to allocate available resources among users in order to meet the QOS requirement for criteria such as delay, throughput, packet loss and fairness. There is no specific standard scheduling mechanism stated by IEEE standards, which leaves it for implementer differentiation. There are five QOS service classes defined by IEEE 802.16: Unsolicited Grant Scheme (UGS), Extended Real Time Polling Service (ertPS), Real Time Polling Service (rtPS), Non Real Time Polling Service (nrtPS) and Best Effort Service (BE). Each class has different QOS parameter requirements for throughput and delay/jitter constraints. This paper proposes Modified Weighted Fair Queuing (MWFQ) scheduling scenario which was based on Weighted Round Robin (WRR) and Weighted Fair Queuing (WFQ). The performance of MWFQ was assessed by using above five QoS criteria. The simulation shows that using the concept of total packet size calculation improves the network's performance.

  19. The Study of MSADQ/CDMA Protocol in Voice/Data Integration Packet Networks

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    A new packet medium access protocol, namely, minislot signalingaccess based on distributed queues(MSADQ/CDMA), is proposed in voice and data intergration CDMA networks. The MSADQ protocol is based on distributed queues and collision resolution algorithm. Through proper management of the PN codes, the number of random competition collision reduces greatly, the multiple access interference (MAI) decreases. It has several special access signaling channels to carry the voice and data access request. Each slot is devided into several control minislots (CMSs), in which the Data Terminals (DT) or Voice Terminals (VT) transmit their request. According to the voice and data traffic character, the signaling access structure is proposed. The code assign rules and queue managing rules are also proposed to ensure the QoS requirement of each traffic. Comparisions with other three protocol are developed by simulation, which shows that MSADQ/CDMA protocol occupies less PN codes, but still has very good performance.

  20. Rolling bearing fault diagnosis using adaptive deep belief network with dual-tree complex wavelet packet.

    Science.gov (United States)

    Shao, Haidong; Jiang, Hongkai; Wang, Fuan; Wang, Yanan

    2017-07-01

    Automatic and accurate identification of rolling bearing fault categories, especially for the fault severities and compound faults, is a challenge in rotating machinery fault diagnosis. For this purpose, a novel method called adaptive deep belief network (DBN) with dual-tree complex wavelet packet (DTCWPT) is developed in this paper. DTCWPT is used to preprocess the vibration signals to refine the fault characteristics information, and an original feature set is designed from each frequency-band signal of DTCWPT. An adaptive DBN is constructed to improve the convergence rate and identification accuracy with multiple stacked adaptive restricted Boltzmann machines (RBMs). The proposed method is applied to the fault diagnosis of rolling bearings. The results confirm that the proposed method is more effective than the existing methods. Copyright © 2017 ISA. Published by Elsevier Ltd. All rights reserved.

  1. H-Seda: Partial Packet Recovery with Heterogeneous Block Sizes for Wireless Sensor Networks

    KAUST Repository

    Meer, Ammar M.

    2012-12-08

    Wireless sensor networks (WSN) have been largely used in various applications due to its ease of deployment and scalability. The throughput of such networks, however, suffers from high bit error rates mainly because of medium characteristics. Maximizing bandwidth utilization while maintaining low frame error rate has been an interesting problem. Frame fragmentation into small blocks with dedicated error detection codes per block can reduce the unnecessary retransmission of the correctly received blocks. The optimal block size, however, varies based on the wireless channel conditions. In addition, blocks within a frame can have different optimal sizes based on the variations on interference patterns. This thesis studies two dynamic partial packet recovery approaches experimentally over several interference intensities with various transmission-power levels. It also proposes a dynamic data link layer protocol: Hybrid Seda (H-Seda). H-Seda effectively addresses the challenges associated with dynamic partitioning of blocks while taking the observed error patterns into consideration. The design of H-Seda is discussed in details and compared to other previous approaches, namely Seda+ and Seda. The implementation of H-Seda shows substantial enhancements over fixed-size partial packet recovery protocols, achieving up to 2.5x improvement in throughput when the channel condition is noisy, while delay experienced decreases to only 14 % of the delay observed in Seda. On average, it shows 35% gain in goodput across all channel conditions used in our experiments. This significant improvement is due to the selective nature of H-Seda which minimizes retransmission overhead by selecting the appropriate number of blocks in each data frame. Additionally, H-Seda successfully reduces block overhead by 50% through removing block number field reaching to better performance when channel conditions are identical.

  2. Towards effective and robust list-based packet filter for signature-based network intrusion detection: an engineering approach

    DEFF Research Database (Denmark)

    Meng, Weizhi; Li, Wenjuan; Kwok, Lam For

    2017-01-01

    Network intrusion detection systems (NIDSs) which aim to identify various attacks, have become an essential part of current security infrastructure. In particular, signature-based NIDSs are being widely implemented in industry due to their low rate of false alarms. However, the signature matching...... this problem, packet filtration is a promising solution to reduce unwanted traffic. Motivated by this, in this work, a list-based packet filter was designed and an engineering method of combining both blacklist and whitelist techniques was introduced. To further secure such filters against IP spoofing attacks...... in traffic filtration as well as workload reduction, and is robust against IP spoofing attacks....

  3. Estimation of Frame Independent and Enhancement Components for Speech Communication over Packet Networks

    DEFF Research Database (Denmark)

    Giacobello, Daniele; Murthi, Manohar N.; Christensen, Mads Græsbøll

    2010-01-01

    In this paper, we describe a new approach to cope with packet loss in speech coders. The idea is to split the information present in each speech packet into two components, one to independently decode the given speech frame and one to enhance it by exploiting interframe dependencies. The scheme...... is based on sparse linear prediction and a redefinition of the analysis-by-synthesis process. We present Mean Opinion Scores for the presented coder with different degrees of packet loss and show that it performs similarly to frame dependent coders for low packet loss probability and similarly to frame...

  4. An analytical model for perpetual network codes in packet erasure channels

    DEFF Research Database (Denmark)

    Pahlevani, Peyman; Crisostomo, Sergio; Roetter, Daniel Enrique Lucani

    2016-01-01

    is highly dependent on a parameter called the width (ωω), which represents the number of consecutive non-zero coding coefficient present in each coded packet after a pivot element. We provide a mathematical analysis based on the width of the coding vector for the number of transmitted packets and validate...

  5. Automatic sleep stage classification based on EEG signals by using neural networks and wavelet packet coefficients.

    Science.gov (United States)

    Ebrahimi, Farideh; Mikaeili, Mohammad; Estrada, Edson; Nazeran, Homer

    2008-01-01

    Currently in the world there is an alarming number of people who suffer from sleep disorders. A number of biomedical signals, such as EEG, EMG, ECG and EOG are used in sleep labs among others for diagnosis and treatment of sleep related disorders. The usual method for sleep stage classification is visual inspection by a sleep specialist. This is a very time consuming and laborious exercise. Automatic sleep stage classification can facilitate this process. The definition of sleep stages and the sleep literature show that EEG signals are similar in Stage 1 of non-rapid eye movement (NREM) sleep and rapid eye movement (REM) sleep. Therefore, in this work an attempt was made to classify four sleep stages consisting of Awake, Stage 1 + REM, Stage 2 and Slow Wave Stage based on the EEG signal alone. Wavelet packet coefficients and artificial neural networks were deployed for this purpose. Seven all night recordings from Physionet database were used in the study. The results demonstrated that these four sleep stages could be automatically discriminated from each other with a specificity of 94.4 +/- 4.5%, a of sensitivity 84.2+3.9% and an accuracy of 93.0 +/- 4.0%.

  6. Synchronization Control for a Class of Discrete-Time Dynamical Networks With Packet Dropouts: A Coding-Decoding-Based Approach.

    Science.gov (United States)

    Wang, Licheng; Wang, Zidong; Han, Qing-Long; Wei, Guoliang

    2017-09-06

    The synchronization control problem is investigated for a class of discrete-time dynamical networks with packet dropouts via a coding-decoding-based approach. The data is transmitted through digital communication channels and only the sequence of finite coded signals is sent to the controller. A series of mutually independent Bernoulli distributed random variables is utilized to model the packet dropout phenomenon occurring in the transmissions of coded signals. The purpose of the addressed synchronization control problem is to design a suitable coding-decoding procedure for each node, based on which an efficient decoder-based control protocol is developed to guarantee that the closed-loop network achieves the desired synchronization performance. By applying a modified uniform quantization approach and the Kronecker product technique, criteria for ensuring the detectability of the dynamical network are established by means of the size of the coding alphabet, the coding period and the probability information of packet dropouts. Subsequently, by resorting to the input-to-state stability theory, the desired controller parameter is obtained in terms of the solutions to a certain set of inequality constraints which can be solved effectively via available software packages. Finally, two simulation examples are provided to demonstrate the effectiveness of the obtained results.

  7. New hybrid frequency reuse method for packet loss minimization in LTE network.

    Science.gov (United States)

    Ali, Nora A; El-Dakroury, Mohamed A; El-Soudani, Magdi; ElSayed, Hany M; Daoud, Ramez M; Amer, Hassanein H

    2015-11-01

    This paper investigates the problem of inter-cell interference (ICI) in Long Term Evolution (LTE) mobile systems, which is one of the main problems that causes loss of packets between the base station and the mobile station. Recently, different frequency reuse methods, such as soft and fractional frequency reuse, have been introduced in order to mitigate this type of interference. In this paper, minimizing the packet loss between the base station and the mobile station is the main concern. Soft Frequency Reuse (SFR), which is the most popular frequency reuse method, is examined and the amount of packet loss is measured. In order to reduce packet loss, a new hybrid frequency reuse method is implemented. In this method, each cell occupies the same bandwidth of the SFR, but the total system bandwidth is greater than in SFR. This will provide the new method with a lot of new sub-carriers from the neighboring cells to reduce the ICI which represents a big problem in many applications and causes a lot of packets loss. It is found that the new hybrid frequency reuse method has noticeable improvement in the amount of packet loss compared to SFR method in the different frequency bands. Traffic congestion management in Intelligent Transportation system (ITS) is one of the important applications that is affected by the packet loss due to the large amount of traffic that is exchanged between the base station and the mobile node. Therefore, it is used as a studied application for the proposed frequency reuse method and the improvement in the amount of packet loss reached 49.4% in some frequency bands using the new hybrid frequency reuse method.

  8. On the Coded Packet Relay Network in the Presence of Neighbors:Benefits of Speaking in a Crowded Room

    OpenAIRE

    Khamfroush, Hana; Pahlevani, Peyman; Roetter, Daniel Enrique Lucani; Hundebøll, Martin; Fitzek, Frank

    2014-01-01

    This paper studies the problem of optimal use of a relay for reducing the transmission time of data packets from a source to a destination using network coding. More importantly, we address an effect that is typically overlooked in previous studies: the presence of active transmitting nodes in the neighborhood of such devices, which is typical in wireless mesh networks. We show that in systems with a fair medium access control mechanism (MAC), the use of a relay in a crowded medium brings for...

  9. An Experimental Exploration of the Impact of Network-Level Packet Loss on Network Intrusion Detection

    Science.gov (United States)

    2015-08-01

    fast recovery algorithms. Freemont (CA): Internet Engineering Task Force; 1997 Jan. RFC No.: 2001. 2. Smith SC, Hammell RJ, Parker TW, Marvel LM. A...2014. p. 1–6. 3. Sangster B, O’Connor T, Cook T, Fanelli R, Dean E , Adams WJ, Morrell C, Conti G. Toward instrumenting network warfare competitions

  10. Lambda network having 2.sup.m-1 nodes in each of m stages with each node coupled to four other nodes for bidirectional routing of data packets between nodes

    Science.gov (United States)

    Napolitano, Jr., Leonard M.

    1995-01-01

    The Lambda network is a single stage, packet-switched interprocessor communication network for a distributed memory, parallel processor computer. Its design arises from the desired network characteristics of minimizing mean and maximum packet transfer time, local routing, expandability, deadlock avoidance, and fault tolerance. The network is based on fixed degree nodes and has mean and maximum packet transfer distances where n is the number of processors. The routing method is detailed, as are methods for expandability, deadlock avoidance, and fault tolerance.

  11. An improved packet structure

    KAUST Repository

    Bader, Ahmed

    2014-01-01

    A multihop network transmits a packet including a RACH area and a hop number. The RACH area includes a list of subcarriers. A source node in the network dynamically determines the size of the RACH area. A node in the network performs an open-loop transmit power control.

  12. An improved packet structure

    KAUST Repository

    Bader, Ahmed

    2014-05-22

    A multihop network transmits a packet including a RACH area and a hop number. The RACH area includes a list of subcarriers. A source node in the network dynamically determines the size of the RACH area. A node in the network performs an open-loop transmit power control.

  13. An Underlay Communication Channel for 5G Cognitive Mesh Networks: Packet Design, Implementation, Analysis, and Experimental Results

    Energy Technology Data Exchange (ETDEWEB)

    Tarek Haddadin; Stephen Andrew Laraway; Arslan Majid; Taylor Sibbett; Daryl Leon Wasden; Brandon F Lo; Lloyd Landon; David Couch; Hussein Moradi; Behrouz Farhang-Boroujeny

    2016-04-01

    This paper proposes and presents the design and implementation of an underlay communication channel (UCC) for 5G cognitive mesh networks. The UCC builds its waveform based on filter bank multicarrier spread spectrum (FB-MCSS) signaling. The use of this novel spread spectrum signaling allows the device-to-device (D2D) user equipments (UEs) to communicate at a level well below noise temperature and hence, minimize taxation on macro-cell/small-cell base stations and their UEs in 5G wireless systems. Moreover, the use of filter banks allows us to avoid those portions of the spectrum that are in use by macro-cell and small-cell users. Hence, both D2D-to-cellular and cellular-to-D2D interference will be very close to none. We propose a specific packet for UCC and develop algorithms for packet detection, timing acquisition and tracking, as well as channel estimation and equalization. We also present the detail of an implementation of the proposed transceiver on a software radio platform and compare our experimental results with those from a theoretical analysis of our packet detection algorithm.

  14. A Study of Quality of Service Communication for High-Speed Packet-Switching Computer Sub-Networks

    Science.gov (United States)

    Cui, Zhenqian

    1999-01-01

    In this thesis, we analyze various factors that affect quality of service (QoS) communication in high-speed, packet-switching sub-networks. We hypothesize that sub-network-wide bandwidth reservation and guaranteed CPU processing power at endpoint systems for handling data traffic are indispensable to achieving hard end-to-end quality of service. Different bandwidth reservation strategies, traffic characterization schemes, and scheduling algorithms affect the network resources and CPU usage as well as the extent that QoS can be achieved. In order to analyze those factors, we design and implement a communication layer. Our experimental analysis supports our research hypothesis. The Resource ReSerVation Protocol (RSVP) is designed to realize resource reservation. Our analysis of RSVP shows that using RSVP solely is insufficient to provide hard end-to-end quality of service in a high-speed sub-network. Analysis of the IEEE 802.lp protocol also supports the research hypothesis.

  15. Compensation of position errors in passivity based teleoperation over packet switched communication networks

    NARCIS (Netherlands)

    Secchi, C; Stramigioli, Stefano; Fantuzzi, C.

    Because of the use of scattering based communication channels, passivity based telemanipulation systems can be subject to a steady state position error between master and slave robots. In this paper, we consider the case in which the passive master and slave sides communicate through a packet

  16. An efficient multi-carrier position-based packet forwarding protocol for wireless sensor networks

    KAUST Repository

    Bader, Ahmed; Abed-Meraim, Karim; Alouini, Mohamed-Slim

    2012-01-01

    in this paper. In contrast to existing beaconless protocols, the proposed protocol is designed such that it eliminates the need for potential relays to undergo a relay selection process. Rather, any eligible relay may decide to forward the packet ahead, thus

  17. Modified Aggressive Packet Combining Scheme

    International Nuclear Information System (INIS)

    Bhunia, C.T.

    2010-06-01

    In this letter, a few schemes are presented to improve the performance of aggressive packet combining scheme (APC). To combat error in computer/data communication networks, ARQ (Automatic Repeat Request) techniques are used. Several modifications to improve the performance of ARQ are suggested by recent research and are found in literature. The important modifications are majority packet combining scheme (MjPC proposed by Wicker), packet combining scheme (PC proposed by Chakraborty), modified packet combining scheme (MPC proposed by Bhunia), and packet reversed packet combining (PRPC proposed by Bhunia) scheme. These modifications are appropriate for improving throughput of conventional ARQ protocols. Leung proposed an idea of APC for error control in wireless networks with the basic objective of error control in uplink wireless data network. We suggest a few modifications of APC to improve its performance in terms of higher throughput, lower delay and higher error correction capability. (author)

  18. Technology Corner: Internet Packet Sniffers

    Directory of Open Access Journals (Sweden)

    Nick Flor

    2011-03-01

    Full Text Available A packet sniffer is a piece of software that allows a person to eavesdrop on computer communications over the internet.  A packet sniffer can be used as a diagnostic tool by network administrators or as a spying tool by hackers who can use it to steal passwords and other private information from computer users.  Whether you are a network administrator or information assurance specialist, it helps to have a detailed understanding of how packet sniffers work.  And one of the best ways to acquire such an understanding is to build and modify an actual packet sniffer.

  19. A Novel Error Resilient Scheme for Wavelet-based Image Coding Over Packet Networks

    OpenAIRE

    WenZhu Sun; HongYu Wang; DaXing Qian

    2012-01-01

    this paper presents a robust transmission strategy for wavelet based scalable bit stream over packet erasure channel. By taking the advantage of the bit plane coding and the multiple description coding, the proposed strategy adopts layered multiple description coding (LMDC) for the embedded wavelet coders to improve the error resistant capability of the important bit planes in the meaning of D(R) function. Then, the post-compression rate-distortion (PCRD) optimization process is used to impro...

  20. Combining SDM-Based Circuit Switching with Packet Switching in a Router for On-Chip Networks

    Directory of Open Access Journals (Sweden)

    Angelo Kuti Lusala

    2012-01-01

    Full Text Available A Hybrid router architecture for Networks-on-Chip “NoC” is presented, it combines Spatial Division Multiplexing “SDM” based circuit switching and packet switching in order to efficiently and separately handle both streaming and best-effort traffic generated in real-time applications. Furthermore the SDM technique is combined with Time Division Multiplexing “TDM” technique in the circuit switching part in order to increase path diversity, thus improving throughput while sharing communication resources among multiple connections. Combining these two techniques allows mitigating the poor resource usage inherent to circuit switching. In this way Quality of Service “QoS” is easily provided for the streaming traffic through the circuit-switched sub-router while the packet-switched sub-router handles best-effort traffic. The proposed hybrid router architectures were synthesized, placed and routed on an FPGA. Results show that a practicable Network-on-Chip “NoC” can be built using the proposed router architectures. 7 × 7 mesh NoCs were simulated in SystemC. Simulation results show that the probability of establishing paths through the NoC increases with the number of sub-channels and has its highest value when combining SDM with TDM, thereby significantly reducing contention in the NoC.

  1. Packet Classification by Multilevel Cutting of the Classification Space: An Algorithmic-Architectural Solution for IP Packet Classification in Next Generation Networks

    Directory of Open Access Journals (Sweden)

    Motasem Aldiab

    2008-01-01

    Full Text Available Traditionally, the Internet provides only a “best-effort” service, treating all packets going to the same destination equally. However, providing differentiated services for different users based on their quality requirements is increasingly becoming a demanding issue. For this, routers need to have the capability to distinguish and isolate traffic belonging to different flows. This ability to determine the flow each packet belongs to is called packet classification. Technology vendors are reluctant to support algorithmic solutions for classification due to their nondeterministic performance. Although content addressable memories (CAMs are favoured by technology vendors due to their deterministic high-lookup rates, they suffer from the problems of high-power consumption and high-silicon cost. This paper provides a new algorithmic-architectural solution for packet classification that mixes CAMs with algorithms based on multilevel cutting of the classification space into smaller spaces. The provided solution utilizes the geometrical distribution of rules in the classification space. It provides the deterministic performance of CAMs, support for dynamic updates, and added flexibility for system designers.

  2. Classification of epileptic seizures using wavelet packet log energy and norm entropies with recurrent Elman neural network classifier.

    Science.gov (United States)

    Raghu, S; Sriraam, N; Kumar, G Pradeep

    2017-02-01

    Electroencephalogram shortly termed as EEG is considered as the fundamental segment for the assessment of the neural activities in the brain. In cognitive neuroscience domain, EEG-based assessment method is found to be superior due to its non-invasive ability to detect deep brain structure while exhibiting superior spatial resolutions. Especially for studying the neurodynamic behavior of epileptic seizures, EEG recordings reflect the neuronal activity of the brain and thus provide required clinical diagnostic information for the neurologist. This specific proposed study makes use of wavelet packet based log and norm entropies with a recurrent Elman neural network (REN) for the automated detection of epileptic seizures. Three conditions, normal, pre-ictal and epileptic EEG recordings were considered for the proposed study. An adaptive Weiner filter was initially applied to remove the power line noise of 50 Hz from raw EEG recordings. Raw EEGs were segmented into 1 s patterns to ensure stationarity of the signal. Then wavelet packet using Haar wavelet with a five level decomposition was introduced and two entropies, log and norm were estimated and were applied to REN classifier to perform binary classification. The non-linear Wilcoxon statistical test was applied to observe the variation in the features under these conditions. The effect of log energy entropy (without wavelets) was also studied. It was found from the simulation results that the wavelet packet log entropy with REN classifier yielded a classification accuracy of 99.70 % for normal-pre-ictal, 99.70 % for normal-epileptic and 99.85 % for pre-ictal-epileptic.

  3. Experimental demonstration of an OpenFlow based software-defined optical network employing packet, fixed and flexible DWDM grid technologies on an international multi-domain testbed.

    Science.gov (United States)

    Channegowda, M; Nejabati, R; Rashidi Fard, M; Peng, S; Amaya, N; Zervas, G; Simeonidou, D; Vilalta, R; Casellas, R; Martínez, R; Muñoz, R; Liu, L; Tsuritani, T; Morita, I; Autenrieth, A; Elbers, J P; Kostecki, P; Kaczmarek, P

    2013-03-11

    Software defined networking (SDN) and flexible grid optical transport technology are two key technologies that allow network operators to customize their infrastructure based on application requirements and therefore minimizing the extra capital and operational costs required for hosting new applications. In this paper, for the first time we report on design, implementation & demonstration of a novel OpenFlow based SDN unified control plane allowing seamless operation across heterogeneous state-of-the-art optical and packet transport domains. We verify and experimentally evaluate OpenFlow protocol extensions for flexible DWDM grid transport technology along with its integration with fixed DWDM grid and layer-2 packet switching.

  4. Sparsely-Packetized Predictive Control by Orthogonal Matching Pursuit

    DEFF Research Database (Denmark)

    Nagahara, Masaaki; Quevedo, Daniel; Østergaard, Jan

    2012-01-01

    We study packetized predictive control, known to be robust against packet dropouts in networked systems. To obtain sparse packets for rate-limited networks, we design control packets via an ℓ0 optimization, which can be eectively solved by orthogonal matching pursuit. Our formulation ensures...

  5. All-optical header recognizer for optical packet switched networks : exploiting nonlinear gain and index dynamics in semiconductor optical amplifiers for low power operation and photonic integration device

    NARCIS (Netherlands)

    Calabretta, N.; Dorren, H.J.S.

    2009-01-01

    The increase of the internet traffic leads to future optical networks requiring tens of Tb/s of capacity. Current electronic circuit switches are limited by the scalability of the electronic switching fabrics, power consumption and dissipation in the opto- electronic conversion. All-optical packet

  6. Dimensioning of 10 Gbit/s all-optical packet switched networks based on optical label swapping routers with multistage 2R regeneration.

    Science.gov (United States)

    Puerto, G; Ortega, B; Manzanedo, M D; Martínez, A; Pastor, D; Capmany, J; Kovacs, G

    2006-10-30

    This paper describes both the experimental and theoretical investigations on the cascadability of all-optical routers in optical label swapping networks incorporating a multistage wavelength conversion with 2R regeneration. A full description of a novel experimental setup allows the packet by packet measurement up to 16 hops with 10 Gb/s payload showing 1 dB penalty with 10(-12) bit error rate. Similarly, the simulations on the system allow a prediction on the cascadability of the router up to 64 hops.

  7. Satcom access in the Evolved Packet Core

    NARCIS (Netherlands)

    Cano Soveri, M.D.; Norp, A.H.J.; Popova, M.P.

    2011-01-01

    Satellite communications (Satcom) networks are increasingly integrating with terrestrial communications networks, namely Next Generation Networks (NGN). In the area of NGN the Evolved Packet Core (EPC) is a new network architecture that can support multiple access technologies. When Satcom is

  8. Satcom access in the evolved packet core

    NARCIS (Netherlands)

    Cano, M.D.; Norp, A.H.J.; Popova, M.P.

    2012-01-01

    Satellite communications (Satcom) networks are increasingly integrating with terrestrial communications networks, namely Next Generation Networks (NGN). In the area of NGN the Evolved Packet Core (EPC) is a new network architecture that can support multiple access technologies. When Satcom is

  9. Lambda network having 2{sup m{minus}1} nodes in each of m stages with each node coupled to four other nodes for bidirectional routing of data packets between nodes

    Science.gov (United States)

    Napolitano, L.M. Jr.

    1995-11-28

    The Lambda network is a single stage, packet-switched interprocessor communication network for a distributed memory, parallel processor computer. Its design arises from the desired network characteristics of minimizing mean and maximum packet transfer time, local routing, expandability, deadlock avoidance, and fault tolerance. The network is based on fixed degree nodes and has mean and maximum packet transfer distances where n is the number of processors. The routing method is detailed, as are methods for expandability, deadlock avoidance, and fault tolerance. 14 figs.

  10. The Localized Discovery and Recovery for Query Packet Losses in Wireless Sensor Networks with Distributed Detector Clusters

    Directory of Open Access Journals (Sweden)

    Ryu Miura

    2013-06-01

    Full Text Available An essential application of wireless sensor networks is to successfully respond to user queries. Query packet losses occur in the query dissemination due to wireless communication problems such as interference, multipath fading, packet collisions, etc. The losses of query messages at sensor nodes result in the failure of sensor nodes reporting the requested data. Hence, the reliable and successful dissemination of query messages to sensor nodes is a non-trivial problem. The target of this paper is to enable highly successful query delivery to sensor nodes by localized and energy-efficient discovery, and recovery of query losses. We adopt local and collective cooperation among sensor nodes to increase the success rate of distributed discoveries and recoveries. To enable the scalability in the operations of discoveries and recoveries, we employ a distributed name resolution mechanism at each sensor node to allow sensor nodes to self-detect the correlated queries and query losses, and then efficiently locally respond to the query losses. We prove that the collective discovery of query losses has a high impact on the success of query dissemination and reveal that scalability can be achieved by using the proposed approach. We further study the novel features of the cooperation and competition in the collective recovery at PHY and MAC layers, and show that the appropriate number of detectors can achieve optimal successful recovery rate. We evaluate the proposed approach with both mathematical analyses and computer simulations. The proposed approach enables a high rate of successful delivery of query messages and it results in short route lengths to recover from query losses. The proposed approach is scalable and operates in a fully distributed manner.

  11. STUDY THE EFFECTIVENESS APPLICATIONS OF FUZZY CONTROLLER WITH TWO ENTRANCES IN THE SYSTEM OF ACTIVE QUEUE MANAGEMENT THE PACKETS IN TCP/IP NETWORKS

    Directory of Open Access Journals (Sweden)

    O. V. Nevdachyna

    2016-01-01

    Full Text Available The paper presents an approach to solving the overloading problem in TCP/IP networks. Offered fuzzy controller with two inputs for system of active queue management packages in TCP/IP networks, and investigated its use in these systems with a random change of traffic load. Proposed controller has two inputs, one of which is the value of the difference between the current queue length and the second – the difference between the current level of usage of the buffer. The output of the fuzzy controller calculates the probability of discarding packet.Mathematical model system of active queue management that is studied is presented in an interactive MATLAB system, in wherein also is demonstrated the processes occurring in the system with a random change of traffic load. The research results show that the AQM-system with fuzzy controller with two entrances stable enough maintains the desired current length the queue for sufficiently small values of the probability of dropping/marking packets (at acceptable size of queue q0= 200 packets, the average probability of dropping / marking is not more than 3,5×10–3 or less 0,35% packets is discarded or marked from the total number of incoming packets. The results obtained will help improve the efficiency of the functioning and operation of TCP / IP networks by increasing data transmission quality. this happens due introduction of the proposed controller at the design of new, more efficient routers for networks to minimize the delay of information.

  12. New distributed fusion filtering algorithm based on covariances over sensor networks with random packet dropouts

    Science.gov (United States)

    Caballero-Águila, R.; Hermoso-Carazo, A.; Linares-Pérez, J.

    2017-07-01

    This paper studies the distributed fusion estimation problem from multisensor measured outputs perturbed by correlated noises and uncertainties modelled by random parameter matrices. Each sensor transmits its outputs to a local processor over a packet-erasure channel and, consequently, random losses may occur during transmission. Different white sequences of Bernoulli variables are introduced to model the transmission losses. For the estimation, each lost output is replaced by its estimator based on the information received previously, and only the covariances of the processes involved are used, without requiring the signal evolution model. First, a recursive algorithm for the local least-squares filters is derived by using an innovation approach. Then, the cross-correlation matrices between any two local filters is obtained. Finally, the distributed fusion filter weighted by matrices is obtained from the local filters by applying the least-squares criterion. The performance of the estimators and the influence of both sensor uncertainties and transmission losses on the estimation accuracy are analysed in a numerical example.

  13. Packet telemetry and packet telecommand - The new generation of spacecraft data handling techniques

    Science.gov (United States)

    Hooke, A. J.

    1983-01-01

    Because of rising costs and reduced reliability of spacecraft and ground network hardware and software customization, standardization Packet Telemetry and Packet Telecommand concepts are emerging as viable alternatives. Autonomous packets of data, within each concept, which are created within ground and space application processes through the use of formatting techniques, are switched end-to-end through the space data network to their destination application processes through the use of standard transfer protocols. This process may result in facilitating a high degree of automation and interoperability because of completely mission-independent-designed intermediate data networks. The adoption of an international guideline for future space telemetry formatting of the Packet Telemetry concept, and the advancement of the NASA-ESA Working Group's Packet Telecommand concept to a level of maturity parallel to the of Packet Telemetry are the goals of the Consultative Committee for Space Data Systems. Both the Packet Telemetry and Packet Telecommand concepts are reviewed.

  14. Cloudification of mmwave-based and packet-based fronthaul for future heterogeneous mobile networks

    DEFF Research Database (Denmark)

    Artuso, Matteo; Marcano, Andrea; Christiansen, Henrik Lehrmann

    2015-01-01

    is seen as an enabler for next-generation heterogeneous mobile networks. This allows for simpler base stations and savings in deployment costs, but introduces challenges in the fronthaul network connecting the sites to the processing pool. The fronthaul needs to have very low latency and high capacity......, but the traditional architecture of this network uses point-to-point links between each site and the pool, thus making it impossible to share capacity as the demands change. To address these challenges, a flexible network architecture for the fronthaul is presented that is based on Ethernet to carry the baseband......Current deployments of mobile networks are seriously challenged by increasing capacity demands, and traditional solutions are no longer practical. The use of small cells is considered as a viable technique to meet these demands. In this context, the use of centralized signal processing in a pool...

  15. A packet-switched network for data readout from the LHC inner detector

    International Nuclear Information System (INIS)

    Ostby, J.M.; Sorasen, O.

    1994-01-01

    This paper presents a network which can be used for data fusion in the planned LHC (Large Hadron Collider) ATLAS experiment at CERN. The network named SWIPP (SWitched Interconnection of Parallel Processors), is built of 16 x 16 star switches and protocol engines connected by pairs of optical fibers. Each channel is designed to carry up to 1 Gbps in each direction. The paper will give a brief introduction to SWIPP principles and ASIC implementation. Some of the advantages offered by the network will be mentioned

  16. Identification method of gas-liquid two-phase flow regime based on image wavelet packet information entropy and genetic neural network

    International Nuclear Information System (INIS)

    Zhou Yunlong; Chen Fei; Sun Bin

    2008-01-01

    Based on the characteristic that wavelet packet transform image can be decomposed by different scales, a flow regime identification method based on image wavelet packet information entropy feature and genetic neural network was proposed. Gas-liquid two-phase flow images were captured by digital high speed video systems in horizontal pipe. The information entropy feature from transformation coefficients were extracted using image processing techniques and multi-resolution analysis. The genetic neural network was trained using those eigenvectors, which was reduced by the principal component analysis, as flow regime samples, and the flow regime intelligent identification was realized. The test result showed that image wavelet packet information entropy feature could excellently reflect the difference between seven typical flow regimes, and the genetic neural network with genetic algorithm and BP algorithm merits were with the characteristics of fast convergence for simulation and avoidance of local minimum. The recognition possibility of the network could reach up to about 100%, and a new and effective method was presented for on-line flow regime. (authors)

  17. Subjective Evaluation of Packet Service Performance in UMTS and Heterogeneous Networks

    DEFF Research Database (Denmark)

    Teyeb, Oumer Mohammed; Sørensen, Troels Bundgaard; Mogensen, Preben

    2006-01-01

    Quality of Service (QoS) in mobile telecommunication systems is usually identified by some basic performance metrics such as delay, throughput and jitter. However, the main impact of service quality is on the end user, and as such a detailed study of service performance should involve the end user......, users rated the perceived quality of the services under different network conditions. The users’ ratings are analyzed and the results showed clear trends with very few outliers. The objective and subjective measures also were found to be in line except for one case where a higher layer effect influenced....... In this paper, such an approach is taken where subjective performance evaluation is undertaken for web browsing and video streaming services in Universal Mobile Telecommunication System (UMTS) and a heterogeneous network comprised of UMTS and Wireless LAN (WLAN). Using a real-time network emulation testbed...

  18. Comparison of Available Bandwidth Estimation Techniques in Packet-Switched Mobile Networks

    DEFF Research Database (Denmark)

    López Villa, Dimas; Ubeda Castellanos, Carlos; Teyeb, Oumer Mohammed

    2006-01-01

    The relative contribution of the transport network towards the per-user capacity in mobile telecommunication systems is becoming very important due to the ever increasing air-interface data rates. Thus, resource management procedures such as admission, load and handover control can make use...... of information regarding the available bandwidth in the transport network, as it could end up being the bottleneck rather than the air interface. This paper provides a comparative study of three well known available bandwidth estimation techniques, i.e. TOPP, SLoPS and pathChirp, taking into account...

  19. Packets with deadlines a framework for real-time wireless networks

    CERN Document Server

    Hou, I-Hong

    2013-01-01

    With the explosive increase in the number of mobile devices and applications, it is anticipated that wireless traffic will increase exponentially in the coming years. Moreover, future wireless networks all carry a wide variety of flows, such as video streaming, online gaming, and VoIP, which have various quality of service (QoS) requirements. Therefore, a new mechanism that can provide satisfactory performance to the complete variety of all kinds of flows, in a coherent and unified framework, is needed.In this book, we introduce a framework for real-time wireless networks. This consists of a m

  20. Monitoring Lalu Lintas Jaringan Demilitarized Zone Universitas Negeri Jakarta Menggunakan Sensor Packet Sniffer Pada PRTG Network Monitor

    Directory of Open Access Journals (Sweden)

    M. Ficky Duskarnaen

    2017-06-01

    Full Text Available Universitas Negeri Jakarta mendapat pemberitahuan bahwa server yang berada pada jaringan UNJ melakukan serangan ke server milik NETpilot GmbH pada layanan postfix. Sementara itu jaringan tempat server tersebut berada belum terdapat sistem yang dapat memantau lalu lintas jaringan yang terjadi. Penelitian ini bertujuan untuk melakukan monitoring lalu lintas jaringan pada jaringan Demilitarized Zone Universitas Negeri Jakarta. Penelitian yang dilakukan di Laboratorium Komputer Jurusan Teknik Elektro dan Pustikom (Pusat Teknologi Informasi dan Komputer Universitas Negeri Jakarta pada bulan April sampai dengan Juni 2014 menggunakan metode eksperimen. Dari hasil monitoring tersebut diketahui terdapat server dengan alamat IP 192.168.XXX.XXX menghasilkan lalu lintas data yang sangat besar, beberapa koneksi yang berasal dari server dengan alamat IP 192.168.XXX.XXX memiliki destination port 10026 yang merupakan port default dari salah satu layanan yang diberikan oleh aplikasi postfix. Sehingga kesimpulannya, monitoring lalu lintas jaringan menggunakan sensor Packet Sniffer pada PRTG Network monitor telah dapat menghasilkan laporan lalu lintas data yang terjadi pada jaringan DMZ UNJ setiap hari dan hasil monitoring tersebut dapat digunakan untuk membantu menyelesaikan masalah yang terjadi pada jaringan.

  1. A novel SDN enabled hybrid oiptical packet/circuit switched data centre network - The LIGHTNESS approach

    NARCIS (Netherlands)

    Peng, S.; Simeonidou, D.; Zervas, G.; Nejabati, R.; Yan, Y; Shu, Yi; Spadaro, S.; Perelló, J.; Agraz, F.; Careglio, D.; Dorren, H.J.S.; Miao, W.; Calabretta, N.; Bernini, G.; Ciulli, N.; Sancho, J.C.; Iordache, S.; Becerra, Y.; Farreras, M.; Biancani, M.; Predieri, A.; Proietti, R.; Cao, Z.; Liu, L.; Yoo, S.J.B.

    2014-01-01

    Current over-provisioned and multi-tier data centre networks (DCN) deploy rigid control and management platforms, which are not able to accommodate the ever-growing workload driven by the increasing demand of high-performance data centre (DC) and cloud applications. In response to this, the EC FP7

  2. Path Calculation and Packet Translation for UAV Surveillance in Support of Wireless Sensor Networks

    Science.gov (United States)

    2006-09-01

    Servomechanism,” 2006). The Unicorn and MMALV have different servo arrangements due to the dissimilarity of their steering mechanisms. (2...15. NUMBER OF PAGES 191 14. SUBJECT TERMS Wireless Sensor Network, Contact Interception, Mote, MMALV, Unicorn , Kestrel Autopilot System...26 1. Procerus Unicorn ..............................................................................26 a. Physical

  3. Integrated DoD Voice and Data Networks and Ground Packet Radio Technology

    Science.gov (United States)

    1976-08-01

    as the traffic requirement level increases. Moreover, the satellite switch selection problem is only meaningful over a limited traffic range. When...5: CPU TIMES VS. NUMBER OF SWITCHES SATELLITE SWITCH SELECTION ALGORITHM Computer Used: PDP-10 ♦O’S" means 0 minutes and 5 seconds. 5.30...Saturation Algorithm for Topo\\ogical Design of Parket-Switched Communications Networks," National Te3 ecommunications Conference Proceed- ings, San

  4. Influence of Reduced Mass Flow Rate and Chamber Backpressure on Swirl Injector Fluid Mechanics

    Science.gov (United States)

    Kenny, R Jeremy; Hulka, James R.

    2008-01-01

    Industry interest in variable-thrust liquid rocket engines places a demand on engine injector technology to operate over a wide range of liquid mass flow rates and chamber backpressures. One injection technology of current interest for variable thrust applications is an injector design with swirled fluids. Current swirl injector design methodologies do not take into account how swirl injector design parameters respond to elevated chamber backpressures at less than design mass flow rates. The current work was created to improve state-of-the-art swirl injector design methods in this area. The specific objective was to study the effects of elevated chamber backpressure and off-design mass flow rates on swirl injector fluid mechanics. Using a backpressure chamber with optical access, water was flowed through a swirl injector at various combinations of chamber backpressure and mass flow rates. The film thickness profile down the swirl injector nozzle section was measured through a transparent nozzle section of the injector. High speed video showed measurable increases in the film thickness profile with application of chamber backpressure and mass flow rates less than design. At prescribed combinations of chamber backpressure and injected mass flow rate, a discrete change in the film thickness profile was observed. Measured injector discharge coefficient values showed different trends with increasing chamber backpressure at low mass flow rates as opposed to near-design mass flow rates. Downstream spray angles showed classic changes in morphology as the mass flow rate was decreased below the design value. Increasing chamber backpressure decreased the spray angle at any injection mass flow rate. Experimental measurements and discussion of these results are reported in this paper.

  5. Polling-Based High-Bit-Rate Packet Transfer in a Microcellular Network to Allow Fast Terminals

    Science.gov (United States)

    Hoa, Phan Thanh; Lambertsen, Gaute; Yamada, Takahiko

    A microcellular network will be a good candidate for the future broadband mobile network. It is expected to support high-bit-rate connection for many fast mobile users if the handover is processed fast enough to lessen its impact on QoS requirements. One of the promising techniques is believed to use for the wireless interface in such a microcellular network is the WLAN (Wireless LAN) technique due to its very high wireless channel rate. However, the less capability of mobility support of this technique must be improved to be able to expand its utilization for the microcellular environment. The reason of its less support mobility is large handover latency delay caused by contention-based handover to the new BS (base station) and delay of re-forwarding data from the old to new BS. This paper presents a proposal of multi-polling and dynamic LMC (Logical Macro Cell) to reduce mentioned above delays. Polling frame for an MT (Mobile Terminal) is sent from every BS belonging to the same LMC — a virtual single macro cell that is a multicast group of several adjacent micro-cells in which an MT is communicating. Instead of contending for the medium of a new BS during handover, the MT responds to the polling sent from that new BS to enable the transition. Because only one BS of the LMC receives the polling ACK (acknowledgement) directly from the MT, this ACK frame has to be multicast to all BSs of the same LMC through the terrestrial network to continue sending the next polling cycle at each BS. Moreover, when an MT hands over to a new cell, its current LMC is switched over to a newly corresponding LMC to prevent the future contending for a new LMC. By this way, an MT can do handover between micro-cells of an LMC smoothly because the redundant resource is reserved for it at neighboring cells, no need to contend with others. Our simulation results using the OMNeT++ simulator illustrate the performance achievements of the multi-polling and dynamic LMC scheme in eliminating

  6. Comparison of Ring-Buffer-Based Packet Capture Solutions

    Energy Technology Data Exchange (ETDEWEB)

    Barker, Steven Andrew [Sandia National Lab. (SNL-CA), Livermore, CA (United States)

    2015-10-01

    Traditional packet-capture solutions using commodity hardware incur a large amount of overhead as packets are copied multiple times by the operating system. This overhead slows sensor systems to a point where they are unable to keep up with high bandwidth traffic, resulting in dropped packets. Incomplete packet capture files hinder network monitoring and incident response efforts. While costly commercial hardware exists to capture high bandwidth traffic, several software-based approaches exist to improve packet capture performance using commodity hardware.

  7. Improving TCP Network Performance by Detecting and Reacting to Packet Reordering

    Science.gov (United States)

    Kruse, Hans; Ostermann, Shawn; Allman, Mark

    2003-01-01

    There are many factors governing the performance of TCP-basec applications traversing satellite channels. The end-to-end performance of TCP is known to be degraded by the reordering, delay, noise and asymmetry inherent in geosynchronous systems. This result has been largely based on experiments that evaluate the performance of TCP in single flow tests. While single flow tests are useful for deriving information on the theoretical behavior of TCP and allow for easy diagnosis of problems they do not represent a broad range of realistic situations and therefore cannot be used to authoritatively comment on performance issues. The experiments discussed in this report test TCP s performance in a more dynamic environment with competing traffic flows from hundreds of TCP connections running simultaneously across the satellite channel. Another aspect we investigate is TCP's reaction to bit errors on satellite channels. TCP interprets loss as a sign of network congestion. This causes TCP to reduce its transmission rate leading to reduced performance when loss is due to corruption. We allowed the bit error rate on our satellite channel to vary widely and tested the performance of TCP as a function of these bit error rates. Our results show that the average performance of TCP on satellite channels is good even under conditions of loss as high as bit error rates of 10(exp -5)

  8. Modeling novel back-pressure mechanisms for a 100 Gb/s switch

    DEFF Research Database (Denmark)

    Fagertun, Anna Manolova; Ruepp, Sarah Renée

    2012-01-01

    In this work we evaluate the performance of novel back-pressure mechanisms in a Clos-based 100 Gb/s switch system via OPNET modeler simulations. The effectiveness of the mechanisms under different switch configurations, as well as under different traffic patterns, is presented. Our results indicate...... that the proposed back-pressure techniques can effectively reduce the requirements for buffer space in the different stages of the Clos switch....

  9. Extensible packet processing architecture

    Science.gov (United States)

    Robertson, Perry J.; Hamlet, Jason R.; Pierson, Lyndon G.; Olsberg, Ronald R.; Chun, Guy D.

    2013-08-20

    A technique for distributed packet processing includes sequentially passing packets associated with packet flows between a plurality of processing engines along a flow through data bus linking the plurality of processing engines in series. At least one packet within a given packet flow is marked by a given processing engine to signify by the given processing engine to the other processing engines that the given processing engine has claimed the given packet flow for processing. A processing function is applied to each of the packet flows within the processing engines and the processed packets are output on a time-shared, arbitered data bus coupled to the plurality of processing engines.

  10. Ising model for packet routing control

    International Nuclear Information System (INIS)

    Horiguchi, Tsuyoshi; Takahashi, Hideyuki; Hayashi, Keisuke; Yamaguchi, Chiaki

    2004-01-01

    For packet routing control in computer networks, we propose an Ising model which is defined in order to express competition among a queue length and a distance from a node with a packet to its destination node. By introducing a dynamics for a mean-field value of an Ising spin, we show by computer simulations that effective control of packet routing through priority links is possible

  11. Event-Triggered Fault Estimation for Stochastic Systems over Multi-Hop Relay Networks with Randomly Occurring Sensor Nonlinearities and Packet Dropouts.

    Science.gov (United States)

    Li, Yunji; Peng, Li

    2018-02-28

    Wireless sensors have many new applications where remote estimation is essential. Considering that a remote estimator is located far away from the process and the wireless transmission distance of sensor nodes is limited, sensor nodes always forward data packets to the remote estimator through a series of relays over a multi-hop link. In this paper, we consider a network with sensor nodes and relay nodes where the relay nodes can forward the estimated values to the remote estimator. An event-triggered remote estimator of state and fault with the corresponding data-forwarding scheme is investigated for stochastic systems subject to both randomly occurring nonlinearity and randomly occurring packet dropouts governed by Bernoulli-distributed sequences to achieve a trade-off between estimation accuracy and energy consumption. Recursive Riccati-like matrix equations are established to calculate the estimator gain to minimize an upper bound of the estimator error covariance. Subsequently, a sufficient condition and data-forwarding scheme are presented under which the error covariance is mean-square bounded in the multi-hop links with random packet dropouts. Furthermore, implementation issues of the theoretical results are discussed where a new data-forwarding communication protocol is designed. Finally, the effectiveness of the proposed algorithms and communication protocol are extensively evaluated using an experimental platform that was established for performance evaluation with a sensor and two relay nodes.

  12. Processing of a magnesium alloy by equal-channel angular pressing using a back-pressure

    International Nuclear Information System (INIS)

    Xu Cheng; Xia Kenong; Langdon, Terence G.

    2009-01-01

    Experiments were conducted on the magnesium AZ31 alloy to evaluate the significance of conducting equal-channel angular pressing (ECAP) with a back-pressure. Following processing by ECAP, the values of the Vickers microhardness were recorded on the cross-sectional planes and microstructural observations were undertaken using transmission electron microscopy. The results show an increase in the hardness in the first pass with significant microstructural inhomogeneity and a transition towards a more homogeneous structure with subsequent passes. The grain size was measured as ∼0.9 μm after 8 passes. A comparison with published data on the same alloy processed by ECAP without a back-pressure suggests several advantages in incorporating a back-pressure into ECAP. These advantages include the ability to achieve greater grain refinement, a potential for pressing at lower temperatures and the development of a more rapid evolution towards a homogeneous microstructure.

  13. Stability Analysis of Networked Control Systems with Random Time Delays and Packet Dropouts Modeled by Markov Chains

    Directory of Open Access Journals (Sweden)

    Li Qiu

    2013-01-01

    unified Markov jump model. The random time delays and packet dropouts existed in feedback communication link are modeled by two independent Markov chains; the resulting closed-loop system is described by a new Markovian jump linear system (MJLS with Markov delays. Sufficient conditions of the stochastic stability for NCSs is obtained by constructing a novel Lyapunov functional, and the mode-dependent output feedback controller design method is presented based on linear matrix inequality (LMI technique. A numerical example is given to illustrate the effectiveness of the proposed method.

  14. Deep Packet/Flow Analysis using GPUs

    Energy Technology Data Exchange (ETDEWEB)

    Gong, Qian [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Wu, Wenji [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); DeMar, Phil [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)

    2017-11-12

    Deep packet inspection (DPI) faces severe performance challenges in high-speed networks (40/100 GE) as it requires a large amount of raw computing power and high I/O throughputs. Recently, researchers have tentatively used GPUs to address the above issues and boost the performance of DPI. Typically, DPI applications involve highly complex operations in both per-packet and per-flow data level, often in real-time. The parallel architecture of GPUs fits exceptionally well for per-packet network traffic processing. However, for stateful network protocols such as TCP, their data stream need to be reconstructed in a per-flow level to deliver a consistent content analysis. Since the flow-centric operations are naturally antiparallel and often require large memory space for buffering out-of-sequence packets, they can be problematic for GPUs, whose memory is normally limited to several gigabytes. In this work, we present a highly efficient GPU-based deep packet/flow analysis framework. The proposed design includes a purely GPU-implemented flow tracking and TCP stream reassembly. Instead of buffering and waiting for TCP packets to become in sequence, our framework process the packets in batch and uses a deterministic finite automaton (DFA) with prefix-/suffix- tree method to detect patterns across out-of-sequence packets that happen to be located in different batches. In conclusion, evaluation shows that our code can reassemble and forward tens of millions of packets per second and conduct a stateful signature-based deep packet inspection at 55 Gbit/s using an NVIDIA K40 GPU.

  15. MPEG-compliant joint source/channel coding using discrete cosine transform and substream scheduling for visual communication over packet networks

    Science.gov (United States)

    Kim, Seong-Whan; Suthaharan, Shan; Lee, Heung-Kyu; Rao, K. R.

    2001-01-01

    Quality of Service (QoS)-guarantee in real-time communication for multimedia applications is significantly important. An architectural framework for multimedia networks based on substreams or flows is effectively exploited for combining source and channel coding for multimedia data. But the existing frame by frame approach which includes Moving Pictures Expert Group (MPEG) cannot be neglected because it is a standard. In this paper, first, we designed an MPEG transcoder which converts an MPEG coded stream into variable rate packet sequences to be used for our joint source/channel coding (JSCC) scheme. Second, we designed a classification scheme to partition the packet stream into multiple substreams which have their own QoS requirements. Finally, we designed a management (reservation and scheduling) scheme for substreams to support better perceptual video quality such as the bound of end-to-end jitter. We have shown that our JSCC scheme is better than two other two popular techniques by simulation and real video experiments on the TCP/IP environment.

  16. NEBULAS A High Performance Data-Driven Event-Building Architecture based on an Asynchronous Self-Routing Packet-Switching Network

    CERN Multimedia

    Costa, M; Letheren, M; Djidi, K; Gustafsson, L; Lazraq, T; Minerskjold, M; Tenhunen, H; Manabe, A; Nomachi, M; Watase, Y

    2002-01-01

    RD31 : The project is evaluating a new approach to event building for level-two and level-three processor farms at high rate experiments. It is based on the use of commercial switching fabrics to replace the traditional bus-based architectures used in most previous data acquisition sytems. Switching fabrics permit the construction of parallel, expandable, hardware-driven event builders that can deliver higher aggregate throughput than the bus-based architectures. A standard industrial switching fabric technology is being evaluated. It is based on Asynchronous Transfer Mode (ATM) packet-switching network technology. Commercial, expandable ATM switching fabrics and processor interfaces, now being developed for the future Broadband ISDN infrastructure, could form the basis of an implementation. The goals of the project are to demonstrate the viability of this approach, to evaluate the trade-offs involved in make versus buy options, to study the interfacing of the physics frontend data buffers to such a fabric, a...

  17. Modeling of video traffic in packet networks, low rate video compression, and the development of a lossy+lossless image compression algorithm

    Science.gov (United States)

    Sayood, K.; Chen, Y. C.; Wang, X.

    1992-01-01

    During this reporting period we have worked on three somewhat different problems. These are modeling of video traffic in packet networks, low rate video compression, and the development of a lossy + lossless image compression algorithm, which might have some application in browsing algorithms. The lossy + lossless scheme is an extension of work previously done under this grant. It provides a simple technique for incorporating browsing capability. The low rate coding scheme is also a simple variation on the standard discrete cosine transform (DCT) coding approach. In spite of its simplicity, the approach provides surprisingly high quality reconstructions. The modeling approach is borrowed from the speech recognition literature, and seems to be promising in that it provides a simple way of obtaining an idea about the second order behavior of a particular coding scheme. Details about these are presented.

  18. Energy Analysis of Cascade Heating with High Back-Pressure Large-Scale Steam Turbine

    Directory of Open Access Journals (Sweden)

    Zhihua Ge

    2018-01-01

    Full Text Available To reduce the exergy loss that is caused by the high-grade extraction steam of traditional heating mode of combined heat and power (CHP generating unit, a high back-pressure cascade heating technology for two jointly constructed large-scale steam turbine power generating units is proposed. The Unit 1 makes full use of the exhaust steam heat from high back-pressure turbine, and the Unit 2 uses the original heating mode of extracting steam condensation, which significantly reduces the flow rate of high-grade extraction steam. The typical 2 × 350 MW supercritical CHP units in northern China were selected as object. The boundary conditions for heating were determined based on the actual climatic conditions and heating demands. A model to analyze the performance of the high back-pressure cascade heating supply units for off-design operating conditions was developed. The load distributions between high back-pressure exhaust steam direct supply and extraction steam heating supply were described under various conditions, based on which, the heating efficiency of the CHP units with the high back-pressure cascade heating system was analyzed. The design heating load and maximum heating supply load were determined as well. The results indicate that the average coal consumption rate during the heating season is 205.46 g/kWh for the design heating load after the retrofit, which is about 51.99 g/kWh lower than that of the traditional heating mode. The coal consumption rate of 199.07 g/kWh can be achieved for the maximum heating load. Significant energy saving and CO2 emission reduction are obtained.

  19. Packet Guide to Routing and Switching

    CERN Document Server

    Hartpence, Bruce

    2011-01-01

    Go beyond layer 2 broadcast domains with this in-depth tour of advanced link and internetwork layer protocols, and learn how they enable you to expand to larger topologies. An ideal follow-up to Packet Guide to Core Network Protocols, this concise guide dissects several of these protocols to explain their structure and operation. This isn't a book on packet theory. Author Bruce Hartpence built topologies in a lab as he wrote this guide, and each chapter includes several packet captures. You'll learn about protocol classification, static vs. dynamic topologies, and reasons for installing a pa

  20. A novel lost packets recovery scheme based on visual secret sharing

    Science.gov (United States)

    Lu, Kun; Shan, Hong; Li, Zhi; Niu, Zhao

    2017-08-01

    In this paper, a novel lost packets recovery scheme which encrypts the effective parts of an original packet into two shadow packets based on (2, 2)-threshold XOR-based visual Secret Sharing (VSS) is proposed. The two shadow packets used as watermarks would be embedded into two normal data packets with digital watermarking embedding technology and then sent from one sensor node to another. Each shadow packet would reveal no information of the original packet, which can improve the security of original packet delivery greatly. The two shadow packets which can be extracted from the received two normal data packets delivered from a sensor node can recover the original packet lossless based on XOR-based VSS. The Performance analysis present that the proposed scheme provides essential services as long as possible in the presence of selective forwarding attack. The proposed scheme would not increase the amount of additional traffic, namely, lower energy consumption, which is suitable for Wireless Sensor Network (WSN).

  1. Effects of facility backpressure on the performance and plume of a Hall thruster

    Science.gov (United States)

    Walker, Mitchell Louis Ronald

    2005-07-01

    This dissertation presents research aimed at understanding the relationship between facility background pressure, Hall thruster performance, and plume characteristics. Due to the wide range of facilities used in Hall thruster testing, it is difficult for researchers to make adequate comparisons between data sets because of both dissimilar instrumentation and backpressures. The differences in the data sets are due to the ingestion of background gas into the Hall thruster discharge channel and charge-exchange collisions in the plume. Thus, this research aims to understand facility effects and to develop the tools needed to allow researchers to obtain relevant plume and performance data for a variety of chambers and backpressures. The first portion of this work develops a technique for calibrating a vacuum chamber in terms of pressure to account for elevated backpressures while testing Hall thrusters. Neutral gas background pressure maps of the Large Vacuum Test Facility are created at a series of cold anode flow rates and one hot flow rate at two UM/AFRL P5 5 kW Hall thruster operating conditions. These data show that a cold flow pressure map can be used to approximate the neutral background pressure in the chamber with the thruster in operation. In addition, the data are used to calibrate a numerical model that accurately predicts facility backpressure within a vacuum chamber of specified geometry and pumping speed. The second portion of this work investigates how facility backpressure influences the plume, plume diagnostics, and performance of the P5 Hall thruster. Measurements of the plume and performance characteristics over a wide range of pressures show that ingestion, a decrease in the downstream plasma potential, and broadening of the ion energy distribution function cause the increase in thrust with backpressure. Furthermore, a magnetically-filtered Faraday probe accurately measures ion current density at elevated operating pressures. The third portion of

  2. Lightness : a function-virtualizable software defined data center network with all-optical circuit/packet switching

    NARCIS (Netherlands)

    Saridis, G.; Peng, S.; Yan, Y.; Aguado, A.; Guo, B.; Arslan, M.; Jackson, C.; Miao, W.; Calabretta, N.; Agraz, F.; Spadaro, S.; Bernini, G.; Ciulli, N.; Zervas, G.; Nejabati, R.; Simeonidou, D.

    2016-01-01

    Modern high-performance Data Centers are responsible for delivering a huge variety of cloud applications to the end-users, which are increasingly pushing the limits of currently deployed computing and network infrastructure. All-optical dynamic data center network (DCN) architectures are strong

  3. revivals of Rydberg wave packets

    International Nuclear Information System (INIS)

    Bluhm, R.; Kostelecky, V.A.; Tudose, B.

    1998-01-01

    We examine the revival structure of Rydberg wave packets. The effects of quantum defects on wave packets in alkali-metal atoms and a squeezed-state description of the initial wave packets are also described. We then examine the revival structure of Rydberg wave packets in the presence of an external electric field, i.e., the revival structure of Stark wave packets. These wave packets have energies that depend on two quantum numbers and exhibit new types of interference behaviour

  4. Impact of Packet Sampling on Link Dimensioning

    NARCIS (Netherlands)

    Schmidt, R.D.O.; Sadre, R.; Sperotto, A.; Berg, H. van den; Pras, A.

    2015-01-01

    Link dimensioning is used by network operators to properly provision the capacity of their network links. Proposed methods for link dimensioning often require statistics, such as traffic variance, that need to be calculated from packet-level measurements. In practice, due to increasing traffic

  5. Impact of packet sampling on link dimensioning

    NARCIS (Netherlands)

    de Oliveira Schmidt, R.; Stadler, R.; Sadre, R.; Sperotto, Anna; van den Berg, Hans Leo; Pras, Aiko

    Link dimensioning is used by network operators to properly provision the capacity of their network links. Proposed methods for link dimensioning often require statistics, such as traffic variance, that need to be calculated from packet-level measurements. In practice, due to increasing traffic

  6. Performance comparison between S-ALOHA and R3T protocols for multirate OFFH-CDMA systems in optical packet networks

    Science.gov (United States)

    Inaty, Elie; Raad, Robert; Fortier, Paul; Shalaby, Hossam M.

    2006-12-01

    We discuss two newly proposed multiple-access control (MAC) protocols for multirate optical code-division multiple access (OCDMA) networks. The first protocol is slotted ALOHA/optical fast-frequency-hopping code-division multiple access (S-ALOHA/OFFH-CDMA), and the second is round-robin receiver-transmitter/optical fast-frequency-hopping code-division multiple access (R3/OFFH-CDMA). Our main subject is to exploit the potential of the optical fast-frequency-hopping CDMA using a fiber Bragg grating when jointly used with two different MAC protocols in a link layer as an effective way of integrating multirate traffic. The system throughput and the average packet delay are compared for both systems. It is shown that S-ALOHA is better than R3T when the user's activity and the offered load are high, whereas R3T is better for smaller values. Both protocols can be competitive in terms of the system throughput, with the advantage going to the R3T protocol at a moderate offered load. However, the R3T protocol suffers a higher delay mainly because of the presence of additional modes. Finally, the overlapped OCDMA system always outperforms the variable processing gain (VPG) OCDMA system regardless of the protocol used.

  7. On the Packet Delay Characteristics for Serially-Connected Links using Random Linear Network Coding with and without Recoding

    DEFF Research Database (Denmark)

    Tömösközi, Máté; Fitzek, Frank; Roetter, Daniel Enrique Lucani

    2015-01-01

    Low latency and high reliability is a critical characteristics of many wireless use cases, such as real–time video surveillance. In a dense network the best way to resolve such problems is by utilizing the fastest and most reliable connection to the destination. Classical solutions, such as Reed–...

  8. All-optical packet/circuit switching-based data center network for enhanced scalability, latency and throughput

    NARCIS (Netherlands)

    Perelló, J.; Spadaro, S.; Ricciardi, S.; Careglio, D.; Peng, S.; Nejabati, R.; Zervas, G.; Simeonidou, D.; Predieri, A.; Biancani, M.; Dorren, H.J.S.; Di Lucente, S.; Luo, J.; Calabretta, N.; Bernini, G.; Ciulli, N.; Sancho, J.C.; Iordache, S.; Farreras, M.; Becerra, Y.; Liou, C.; Hussain, I.; Yin, Y.; Liu, L.; Proietti, R.

    2013-01-01

    Applications running inside data centers are enabled through the cooperation of thousands of servers arranged in racks and interconnected together through the data center network. Current DCN architectures based on electronic devices are neither scalable to face the massive growth of DCs, nor

  9. Combined Rate and Power Allocation with Link Scheduling in Wireless Data Packet Relay Networks with Fading Channels

    OpenAIRE

    Subhrakanti Dey; Minyi Huang

    2007-01-01

    We consider a joint rate and power control problem in a wireless data traffic relay network with fading channels. The optimization problem is formulated in terms of power and rate selection, and link transmission scheduling. The objective is to seek high aggregate utility of the relay node when taking into account buffer load management and power constraints. The optimal solution for a single transmitting source is computed by a two-layer dynamic programming algorithm which leads to optimal ...

  10. Revivals of Rydberg wave packets

    International Nuclear Information System (INIS)

    Bluhm, R.; Kostelecky, V.A.; Tudose, B.

    1998-01-01

    We examine the revival structure of Rydberg wave packets. These wave packets exhibit initial classical periodic motion followed by a sequence of collapse, fractional (or full) revivals, and fractional (or full) superrevivals. The effects of quantum defects on wave packets in alkali-metal atoms and a squeezed-state description of the initial wave packets are also considered. We then examine the revival structure of Rydberg wave packets in the presence of an external electric field - that is, the revival structure of Stark wave packets. These wave packets have energies that depend on two quantum numbers and exhibit new types of interference behavior

  11. Rotating quantum Gaussian packets

    International Nuclear Information System (INIS)

    Dodonov, V V

    2015-01-01

    We study two-dimensional quantum Gaussian packets with a fixed value of mean angular momentum. This value is the sum of two independent parts: the ‘external’ momentum related to the motion of the packet center and the ‘internal’ momentum due to quantum fluctuations. The packets minimizing the mean energy of an isotropic oscillator with the fixed mean angular momentum are found. They exist for ‘co-rotating’ external and internal motions, and they have nonzero correlation coefficients between coordinates and momenta, together with some (moderate) amount of quadrature squeezing. Variances of angular momentum and energy are calculated, too. Differences in the behavior of ‘co-rotating’ and ‘anti-rotating’ packets are shown. The time evolution of rotating Gaussian packets is analyzed, including the cases of a charge in a homogeneous magnetic field and a free particle. In the latter case, the effect of initial shrinking of packets with big enough coordinate-momentum correlation coefficients (followed by the well known expansion) is discovered. This happens due to a competition of ‘focusing’ and ‘de-focusing’ in the orthogonal directions. (paper)

  12. Modeling, Parameters Identification, and Control of High Pressure Fuel Cell Back-Pressure Valve

    Directory of Open Access Journals (Sweden)

    Fengxiang Chen

    2014-01-01

    Full Text Available The reactant pressure is crucial to the efficiency and lifespan of a high pressure PEMFC engine. This paper analyses a regulated back-pressure valve (BPV for the cathode outlet flow in a high pressure PEMFC engine, which can achieve precisely pressure control. The modeling, parameters identification, and nonlinear controller design of a BPV system are considered. The identified parameters are used in designing active disturbance rejection controller (ADRC. Simulations and extensive experiments are conducted with the xPC Target and show that the proposed controller can not only achieve good dynamic and static performance but also have strong robustness against parameters’ disturbance and external disturbance.

  13. Evaluation Of Liner Back-pressure Due To Concrete Pore Pressure At Elevated Temperatures

    International Nuclear Information System (INIS)

    James, R.J.; Rashid, Y.R.; Liu, A.S.; Gou, B.

    2006-01-01

    GE's latest evolution of the boiling water reactor, the ESBWR, has innovative passive design features that reduce the number and complexity of active systems, which in turn provide economic advantages while also increasing safety. These passive systems used for emergency cooling also mean that the primary containment system will experience elevated temperatures with longer durations than conventional plants in the event of design basis accidents. During a Loss of Coolant Accident (LOCA), the drywell in the primary containment structure for the ESBWR will be exposed to saturated steam conditions for up to 72 hours following the accident. A containment spray system may be activated that sprays the drywell area with water to condense the steam as part of the recovery operations. The liner back-pressure will build up gradually over the 72 hours as the concrete temperatures increase, and a sudden cool down could cause excessive differential pressure on the liner to develop. For this analysis, it is assumed that the containment spray is activated at the end of the 72-hour period. A back-pressure, acting between the liner and the concrete wall of the containment, can occur as a result of elevated temperatures in the concrete causing steam and saturated vapor pressures to develop from the free water remaining in the pores of the concrete. Additional pore pressure also develops under the elevated temperatures from the non-condensable gases trapped in the concrete pores during the concrete curing process. Any buildup of this pore pressure next to the liner, in excess of the drywell internal pressure, will act to push the liner away from the concrete with a potential for tearing at the liner anchorages. This paper describes the methods and analyses used to quantify this liner back-pressure so that appropriate measures are included in the design of the liner and anchorage system. A pore pressure model is developed that calculates the pressure distribution across the concrete

  14. Combined Rate and Power Allocation with Link Scheduling in Wireless Data Packet Relay Networks with Fading Channels

    Directory of Open Access Journals (Sweden)

    Subhrakanti Dey

    2007-08-01

    Full Text Available We consider a joint rate and power control problem in a wireless data traffic relay network with fading channels. The optimization problem is formulated in terms of power and rate selection, and link transmission scheduling. The objective is to seek high aggregate utility of the relay node when taking into account buffer load management and power constraints. The optimal solution for a single transmitting source is computed by a two-layer dynamic programming algorithm which leads to optimal power, rate, and transmission time allocation at the wireless links. We further consider an optimal power allocation problem for multiple transmitting sources in the same framework. Performances of the resource allocation algorithms including the effect of buffer load control are illustrated via extensive simulation studies.

  15. Optimizing Transmission and Shutdown for Energy-Efficient Real-time Packet Scheduling in Clustered Ad Hoc Networks

    Directory of Open Access Journals (Sweden)

    Rajkumar Ragunathan

    2005-01-01

    Full Text Available Energy efficiency is imperative to enable the deployment of ad hoc networks. Conventional power management focuses independently on the physical or MAC layer and approaches differ depending on the abstraction level. At the physical layer, the fundamental tradeoff between transmission rate and energy is exploited, which leads to transmit as slow as possible. At MAC level, power reduction techniques aim to transmit as fast as possible to maximize the radios power-off interval. The two approaches seem conflicting and it is not obvious which one is the most appropriate. We propose a transmission strategy that optimally mixes both techniques in a multiuser context. We present a cross-layer solution considering the transceiver power characteristics, the varying system load, and the dynamic channel constraints. Based on this, we derive a low-complexity online scheduling algorithm. Results considering an -ary quadrature amplitude modulation radio show that for a range of scenarios a large power reduction is achieved, compared to the case where only scaling or shutdown is considered.

  16. Effect of back-pressure forcing on shock train structures in rectangular channels

    Science.gov (United States)

    Gnani, F.; Zare-Behtash, H.; White, C.; Kontis, K.

    2018-04-01

    The deceleration of a supersonic flow to the subsonic regime inside a high-speed engine occurs through a series of shock waves, known as a shock train. The generation of such a flow structure is due to the interaction between the shock waves and the boundary layer inside a long and narrow duct. The understanding of the physics governing the shock train is vital for the improvement of the design of high-speed engines and the development of flow control strategies. The present paper analyses the sensitivity of the shock train configuration to a back-pressure variation. The complex characteristics of the shock train at an inflow Mach number M = 2 in a channel of constant height are investigated with two-dimensional RANS equations closed by the Wilcox k-ω turbulence model. Under a sinusoidal back-pressure variation, the simulated results indicate that the shock train executes a motion around its mean position that deviates from a perfect sinusoidal profile with variation in oscillation amplitude, frequency, and whether the pressure is first increased or decreased.

  17. Packet models revisited: tandem and priority systems

    NARCIS (Netherlands)

    M.R.H. Mandjes (Michel)

    2004-01-01

    textabstractWe examine two extensions of traditional single-node packet-scale queueing models: tandem networks and (strict) priority systems. Two generic input processes are considered: periodic and Poisson arrivals. For the two-node tandem, an exact expression is derived for the joint distribution

  18. Nondispersive Wave Packets.

    Science.gov (United States)

    Shaarawi, Amr Mohamed

    In this work, nondispersive wavepacket solutions to linear partial differential equations are investigated. These solutions are characterized by infinite energy content; otherwise they are continuous, nonsingular and propagate in free space without spreading out. Examples of such solutions are Berry and Balazs' Airy packet, MacKinnon's wave packet and Brittingham's Focus Wave Mode (FWM). It is demonstrated in this thesis that the infinite energy content is not a basic problem per se and that it can be dealt with in two distinct ways. First these wave packets can be used as bases to construct highly localized, slowly decaying, time-limited pulsed solutions. In the case of the FWMs, this path leads to the formulation of the bidirectional representation, a technique that provides the most natural basis for synthesizing Brittingham-like solutions. This representation is used to derive new exact solutions to the 3-D scalar wave equation. It is also applied to problems involving boundaries, in particular to the propagation of a localized pulse in a infinite acoustic waveguide and to the launchability of such a pulse from the opening of a semi-infinite waveguide. The second approach in dealing with the infinite energy content utilizes the bump-like structure of nondispersive solutions. With an appropriate choice of parameters, these bump fields have very large amplitudes around the centers, in comparison to their tails. In particular, the FWM solutions are used to model massless particles and are capable of providing an interesting interpretation to the results of Young's two slit experiment and to the wave-particle duality of light. The bidirectional representation provides, also, a systematic way of deriving packet solutions to the Klein-Gordon, the Schrodinger and the Dirac equations. Nondispersive solutions of the former two equations are compared to previously derived ones, e.g., the Airy packet and MacKinnon's wave packet.

  19. Quantum wave packet revivals

    International Nuclear Information System (INIS)

    Robinett, R.W.

    2004-01-01

    The numerical prediction, theoretical analysis, and experimental verification of the phenomenon of wave packet revivals in quantum systems has flourished over the last decade and a half. Quantum revivals are characterized by initially localized quantum states which have a short-term, quasi-classical time evolution, which then can spread significantly over several orbits, only to reform later in the form of a quantum revival in which the spreading reverses itself, the wave packet relocalizes, and the semi-classical periodicity is once again evident. Relocalization of the initial wave packet into a number of smaller copies of the initial packet ('minipackets' or 'clones') is also possible, giving rise to fractional revivals. Systems exhibiting such behavior are a fundamental realization of time-dependent interference phenomena for bound states with quantized energies in quantum mechanics and are therefore of wide interest in the physics and chemistry communities. We review the theoretical machinery of quantum wave packet construction leading to the existence of revivals and fractional revivals, in systems with one (or more) quantum number(s), as well as discussing how information on the classical period and revival time is encoded in the energy eigenvalue spectrum. We discuss a number of one-dimensional model systems which exhibit revival behavior, including the infinite well, the quantum bouncer, and others, as well as several two-dimensional integrable quantum billiard systems. Finally, we briefly review the experimental evidence for wave packet revivals in atomic, molecular, and other systems, and related revival phenomena in condensed matter and optical systems

  20. Packet-Based Control Algorithms for Cooperative Surveillance and Reconnaissance

    National Research Council Canada - National Science Library

    Murray, Richard M

    2007-01-01

    ..., and repeated transmissions. Results include analysis and design of estimation and control algorithms in the presence of packet loss and across multi-hop data networks, distributed estimation and sensor fusion algorithms...

  1. Packet-aware transport for video distribution [Invited

    Science.gov (United States)

    Aguirre-Torres, Luis; Rosenfeld, Gady; Bruckman, Leon; O'Connor, Mannix

    2006-05-01

    We describe a solution based on resilient packet rings (RPR) for the distribution of broadcast video and video-on-demand (VoD) content over a packet-aware transport network. The proposed solution is based on our experience in the design and deployment of nationwide Triple Play networks and relies on technologies such as RPR, multiprotocol label switching (MPLS), and virtual private LAN service (VPLS) to provide the most efficient solution in terms of utilization, scalability, and availability.

  2. Election '88: Teacher Packet.

    Science.gov (United States)

    North Carolina State Dept. of Public Instruction, Raleigh. Div. of Social Studies Education.

    This materials packet contains information on teaching about the electoral process and the elections of 1988, and on participation in a mock election for students whose schools would take part in the 1988 North Carolina Mock Election. Suggestions for teachers' preparations are given, including a classroom skit and a mock candidates' election…

  3. Efcient Computation of Buffer Capacities for Cyclo-Static Real-Time Systems with Back-Pressure

    NARCIS (Netherlands)

    Wiggers, M.H.; Bekooij, Marco; Bekooij, Marco Jan Gerrit; Jansen, P.G.; Smit, Gerardus Johannes Maria

    2006-01-01

    A key step in the design of cyclo-static real-time systems is the determination of buffer capacities. In our multiprocessor system, we apply back-pressure, which means that tasks wait for space in output buffers. Consequently buffer capacities affect the throughput. This requires the derivation of

  4. A first packet processing subdomain cluster model based on SDN

    Science.gov (United States)

    Chen, Mingyong; Wu, Weimin

    2017-08-01

    For the current controller cluster packet processing performance bottlenecks and controller downtime problems. An SDN controller is proposed to allocate the priority of each device in the SDN (Software Defined Network) network, and the domain contains several network devices and Controller, the controller is responsible for managing the network equipment within the domain, the switch performs data delivery based on the load of the controller, processing network equipment data. The experimental results show that the model can effectively solve the risk of single point failure of the controller, and can solve the performance bottleneck of the first packet processing.

  5. SECURE SERVICE DISCOVERY BASED ON PROBE PACKET MECHANISM FOR MANETS

    Directory of Open Access Journals (Sweden)

    S. Pariselvam

    2015-03-01

    Full Text Available In MANETs, Service discovery process is always considered to be crucial since they do not possess a centralized infrastructure for communication. Moreover, different services available through the network necessitate varying categories. Hence, a need arises for devising a secure probe based service discovery mechanism to reduce the complexity in providing the services to the network users. In this paper, we propose a Secure Service Discovery Based on Probe Packet Mechanism (SSDPPM for identifying the DoS attack in MANETs, which depicts a new approach for estimating the level of trust present in each and every routing path of a mobile ad hoc network by using probe packets. Probing based service discovery mechanisms mainly identifies a mobile node’s genuineness using a test packet called probe that travels the entire network for the sake of computing the degree of trust maintained between the mobile nodes and it’s attributed impact towards the network performance. The performance of SSDPPM is investigated through a wide range of network related parameters like packet delivery, throughput, Control overhead and total overhead using the version ns-2.26 network simulator. This mechanism SSDPPM, improves the performance of the network in an average by 23% and 19% in terms of packet delivery ratio and throughput than the existing service discovery mechanisms available in the literature.

  6. Hardware Realization of an Ethernet Packet Analyzer Search Engine

    Science.gov (United States)

    2000-06-30

    specific for the home automation industry. This analyzer will be at the gateway of a network and analyze Ethernet packets as they go by. It will keep... home automation and not the computer network. This system is a stand-alone real-time network analyzer capable of decoding Ethernet protocols. The

  7. Scalable Packet Classification with Hash Tables

    Science.gov (United States)

    Wang, Pi-Chung

    In the last decade, the technique of packet classification has been widely deployed in various network devices, including routers, firewalls and network intrusion detection systems. In this work, we improve the performance of packet classification by using multiple hash tables. The existing hash-based algorithms have superior scalability with respect to the required space; however, their search performance may not be comparable to other algorithms. To improve the search performance, we propose a tuple reordering algorithm to minimize the number of accessed hash tables with the aid of bitmaps. We also use pre-computation to ensure the accuracy of our search procedure. Performance evaluation based on both real and synthetic filter databases shows that our scheme is effective and scalable and the pre-computation cost is moderate.

  8. Packet Header Compression for the Internet of Things

    Directory of Open Access Journals (Sweden)

    Pekka KOSKELA

    2016-01-01

    Full Text Available Due to the extensive growth of Internet of Things (IoT, the number of wireless devices connected to the Internet is forecasted to grow to 26 billion units installed in 2020. This will challenge both the energy efficiency of wireless battery powered devices and the bandwidth of wireless networks. One solution for both challenges could be to utilize packet header compression. This paper reviews different packet compression, and especially packet header compression, methods and studies the performance of Robust Header Compression (ROHC in low speed radio networks such as XBEE, and in high speed radio networks such as LTE and WLAN. In all networks, the compressing and decompressing processing causes extra delay and power consumption, but in low speed networks, energy can still be saved due to the shorter transmission time.

  9. Packetized Media Streaming with Comprehensive Exploitation of Feedback Information

    OpenAIRE

    De Vleeschouwer, C.; Frossard, P.

    2005-01-01

    This paper addresses the problem of streaming packetized media over a lossy packet network, with sender-driven (re)transmission using acknowledgement feedback. The different transmission scenarios associated to a group of interdependent media data units are abstracted in terms of a finite alphabet of policies, for each single data unit. A rate-distortion optimized markovian framework is proposed, which supports the use of comprehensive feedback information. Contrarily to previous works in rat...

  10. Controlled Quantum Packets

    Science.gov (United States)

    DeMartino, Salvatore; DeSiena, Silvio

    1996-01-01

    We look at time evolution of a physical system from the point of view of dynamical control theory. Normally we solve motion equation with a given external potential and we obtain time evolution. Standard examples are the trajectories in classical mechanics or the wave functions in Quantum Mechanics. In the control theory, we have the configurational variables of a physical system, we choose a velocity field and with a suited strategy we force the physical system to have a well defined evolution. The evolution of the system is the 'premium' that the controller receives if he has adopted the right strategy. The strategy is given by well suited laboratory devices. The control mechanisms are in many cases non linear; it is necessary, namely, a feedback mechanism to retain in time the selected evolution. Our aim is to introduce a scheme to obtain Quantum wave packets by control theory. The program is to choose the characteristics of a packet, that is, the equation of evolution for its centre and a controlled dispersion, and to give a building scheme from some initial state (for example a solution of stationary Schroedinger equation). It seems natural in this view to use stochastic approach to Quantum Mechanics, that is, Stochastic Mechanics [S.M.]. It is a quantization scheme different from ordinary ones only formally. This approach introduces in quantum theory the whole mathematical apparatus of stochastic control theory. Stochastic Mechanics, in our view, is more intuitive when we want to study all the classical-like problems. We apply our scheme to build two classes of quantum packets both derived generalizing some properties of coherent states.

  11. TCP Packet Trace Analysis. M.S. Thesis

    Science.gov (United States)

    Shepard, Timothy J.

    1991-01-01

    Examination of a trace of packets collected from the network is often the only method available for diagnosing protocol performance problems in computer networks. This thesis explores the use of packet traces to diagnose performance problems of the transport protocol TCP. Unfortunately, manual examination of these traces can be so tedious that effective analysis is not possible. The primary contribution of this thesis is a graphical method of displaying the packet trace which greatly reduce, the tediousness of examining a packet trace. The graphical method is demonstrated by the examination of some packet traces of typical TCP connections. The performance of two different implementations of TCP sending data across a particular network path is compared. Traces many thousands of packets long are used to demonstrate how effectively the graphical method simplifies examination of long complicated traces. In the comparison of the two TCP implementations, the burstiness of the TCP transmitter appeared to be related to the achieved throughput. A method of quantifying this burstiness is presented and its possible relevance to understanding the performance of TCP is discussed.

  12. Revivals of Quantum Wave Packets

    OpenAIRE

    Bluhm, Robert; Kostelecky, Alan; Porter, James; Tudose, Bogdan

    1997-01-01

    We present a generic treatment of wave-packet revivals for quantum-mechanical systems. This treatment permits a classification of certain ideal revival types. For example, wave packets for a particle in a one-dimensional box are shown to exhibit perfect revivals. We also examine the revival structure of wave packets for quantum systems with energies that depend on two quantum numbers. Wave packets in these systems exhibit quantum beats in the initial motion as well as new types of long-term r...

  13. Sensitivity of the optimal parameter settings for a LTE packet scheduler

    NARCIS (Netherlands)

    Fernandez-Diaz, I.; Litjens, R.; van den Berg, C.A.; Dimitrova, D.C.; Spaey, K.

    Advanced packet scheduling schemes in 3G/3G+ mobile networks provide one or more parameters to optimise the trade-off between QoS and resource efficiency. In this paper we study the sensitivity of the optimal parameter setting for packet scheduling in LTE radio networks with respect to various

  14. Tropical Animal Tour Packet. Metro.

    Science.gov (United States)

    Metro Washington Park Zoo, Portland, OR. Educational Services Div.

    This packet is designed to assist teachers in creating a tropical animals lesson plan that centers around a visit to the zoo. A teacher packet is divided into eight parts: (1) goals and objectives; (2) what to expect at the zoo; (3) student activities (preparatory activities, on-site activities, and follow-up activities); (4) background…

  15. A packet switched communications system for GRO

    Science.gov (United States)

    Husain, Shabu; Yang, Wen-Hsing; Vadlamudi, Rani; Valenti, Joseph

    1993-11-01

    This paper describes the packet switched Instrumenters Communication System (ICS) that was developed for the Command Management Facility at GSFC to support the Gamma Ray Observatory (GRO) spacecraft. The GRO ICS serves as a vital science data acquisition link to the GRO scientists to initiate commands for their spacecraft instruments. The system is ready to send and receive messages at any time, 24 hours a day and seven days a week. The system is based on X.25 and the International Standard Organization's (ISO) 7-layer Open Systems Interconnection (OSI) protocol model and has client and server components. The components of the GRO ICS are discussed along with how the Communications Subsystem for Interconnection (CSFI) and Network Control Program Packet Switching Interface (NPSI) software are used in the system.

  16. High-speed packet filtering utilizing stream processors

    Science.gov (United States)

    Hummel, Richard J.; Fulp, Errin W.

    2009-04-01

    Parallel firewalls offer a scalable architecture for the next generation of high-speed networks. While these parallel systems can be implemented using multiple firewalls, the latest generation of stream processors can provide similar benefits with a significantly reduced latency due to locality. This paper describes how the Cell Broadband Engine (CBE), a popular stream processor, can be used as a high-speed packet filter. Results show the CBE can potentially process packets arriving at a rate of 1 Gbps with a latency less than 82 μ-seconds. Performance depends on how well the packet filtering process is translated to the unique stream processor architecture. For example the method used for transmitting data and control messages among the pseudo-independent processor cores has a significant impact on performance. Experimental results will also show the current limitations of a CBE operating system when used to process packets. Possible solutions to these issues will be discussed.

  17. Scattering of accelerated wave packets

    Science.gov (United States)

    Longhi, S.; Horsley, S. A. R.; Della Valle, G.

    2018-03-01

    Wave-packet scattering from a stationary potential is significantly modified when the wave packet is subject to an external time-dependent force during the interaction. In the semiclassical limit, wave-packet motion is simply described by Newtonian equations, and the external force can, for example, cancel the potential force, making a potential barrier transparent. Here we consider wave-packet scattering from reflectionless potentials, where in general the potential becomes reflective when probed by an accelerated wave packet. In the particular case of the recently introduced class of complex Kramers-Kronig potentials we show that a broad class of time-dependent forces can be applied without inducing any scattering, while there is a breakdown of the reflectionless property when there is a broadband distribution of initial particle momentum, involving both positive and negative components.

  18. E-model MOS Estimate Improvement through Jitter Buffer Packet Loss Modelling

    Directory of Open Access Journals (Sweden)

    Adrian Kovac

    2011-01-01

    Full Text Available Proposed article analyses dependence of MOS as a voice call quality (QoS measure estimated through ITU-T E-model under real network conditions with jitter. In this paper, a method of jitter effect is proposed. Jitter as voice packet time uncertainty appears as increased packet loss caused by jitter memory buffer under- or overflow. Jitter buffer behaviour at receiver’s side is modelled as Pareto/D/1/K system with Pareto-distributed packet interarrival times and its performance is experimentally evaluated by using statistic tools. Jitter buffer stochastic model is then incorporated into E-model in an additive manner accounting for network jitter effects via excess packet loss complementing measured network packet loss. Proposed modification of E-model input parameter adds two degrees of freedom in modelling: network jitter and jitter buffer size.

  19. Reynolds-Averaged Turbulence Model Assessment for a Highly Back-Pressured Isolator Flowfield

    Science.gov (United States)

    Baurle, Robert A.; Middleton, Troy F.; Wilson, L. G.

    2012-01-01

    The use of computational fluid dynamics in scramjet engine component development is widespread in the existing literature. Unfortunately, the quantification of model-form uncertainties is rarely addressed with anything other than sensitivity studies, requiring that the computational results be intimately tied to and calibrated against existing test data. This practice must be replaced with a formal uncertainty quantification process for computational fluid dynamics to play an expanded role in the system design, development, and flight certification process. Due to ground test facility limitations, this expanded role is believed to be a requirement by some in the test and evaluation community if scramjet engines are to be given serious consideration as a viable propulsion device. An effort has been initiated at the NASA Langley Research Center to validate several turbulence closure models used for Reynolds-averaged simulations of scramjet isolator flows. The turbulence models considered were the Menter BSL, Menter SST, Wilcox 1998, Wilcox 2006, and the Gatski-Speziale explicit algebraic Reynolds stress models. The simulations were carried out using the VULCAN computational fluid dynamics package developed at the NASA Langley Research Center. A procedure to quantify the numerical errors was developed to account for discretization errors in the validation process. This procedure utilized the grid convergence index defined by Roache as a bounding estimate for the numerical error. The validation data was collected from a mechanically back-pressured constant area (1 2 inch) isolator model with an isolator entrance Mach number of 2.5. As expected, the model-form uncertainty was substantial for the shock-dominated, massively separated flowfield within the isolator as evidenced by a 6 duct height variation in shock train length depending on the turbulence model employed. Generally speaking, the turbulence models that did not include an explicit stress limiter more closely

  20. Multiple descriptions for packetized predictive control

    DEFF Research Database (Denmark)

    Østergaard, Jan; Quevedo, Daniel

    2016-01-01

    be reliably reconstructed at the plant side. For the particular case of LTI plant models and i.i.d. channels, we show that the overall system forms a Markov jump linear system. We provide conditions for mean square stability and derive upper bounds on the operational bit rate of the quantizer to guarantee......In this paper, we propose to use multiple descriptions (MDs) to achieve a high degree of robustness towards random packet delays and erasures in networked control systems. In particular, we consider the scenario, where a data-rate limited channel is located between the controller and the plant...

  1. Packet loss replacement in voip using a recursive low-order autoregressive modelbased speech

    International Nuclear Information System (INIS)

    Miralavi, Seyed Reza; Ghorshi, Seyed; Mortazavi, Mohammad; Choupan, Jeiran

    2011-01-01

    In real-time packet-based communication systems one major problem is misrouted or delayed packets which results in degraded perceived voice quality. When some speech packets are not available on time, the packet is known as lost packet in real-time communication systems. The easiest task of a network terminal receiver is to replace silence for the duration of lost speech segments. In a high quality communication system in order to avoid quality reduction due to packet loss a suitable method and/or algorithm is needed to replace the missing segments of speech. In this paper, we introduce a recursive low order autoregressive (AR) model for replacement of lost speech segment. The evaluation results show that this method has a lower mean square error (MSE) and low complexity compared to the other efficient methods like high-order AR model without any substantial degradation in perceived voice quality.

  2. Physical Watermarking for Securing Cyber-Physical Systems via Packet Drop Injections

    Energy Technology Data Exchange (ETDEWEB)

    Ozel, Omur [Carnegie Mellon Univ., Pittsburgh, PA (United States); Weekrakkody, Sean [Carnegie Mellon Univ., Pittsburgh, PA (United States); Sinopoli, Bruno [Carnegie Mellon Univ., Pittsburgh, PA (United States)

    2017-10-23

    Physical watermarking is a well known solution for detecting integrity attacks on Cyber-Physical Systems (CPSs) such as the smart grid. Here, a random control input is injected into the system in order to authenticate physical dynamics and sensors which may have been corrupted by adversaries. Packet drops may naturally occur in a CPS due to network imperfections. To our knowledge, previous work has not considered the role of packet drops in detecting integrity attacks. In this paper, we investigate the merit of injecting Bernoulli packet drops into the control inputs sent to actuators as a new physical watermarking scheme. With the classical linear quadratic objective function and an independent and identically distributed packet drop injection sequence, we study the effect of packet drops on meeting security and control objectives. Our results indicate that the packet drops could act as a potential physical watermark for attack detection in CPSs.

  3. Packet-switched data communication system of the Paks Nuclear Power Plant, Hungary

    International Nuclear Information System (INIS)

    Szuegyi, M.

    1991-01-01

    Data communication systems are inherent components of the computer network of nuclear power plants. In the PNPP, Hungary, a new packet-switched network has been installed, based on the X25 protocol. It was developed in the framework of the Information Infrastructure Development project of the country. The most important system and software components of the new packet-switched communication system and computer network installed at PNPP are described. (R.P.) 4 refs.; 1 fig

  4. Hardware packet pacing using a DMA in a parallel computer

    Science.gov (United States)

    Chen, Dong; Heidelberger, Phillip; Vranas, Pavlos

    2013-08-13

    Method and system for hardware packet pacing using a direct memory access controller in a parallel computer which, in one aspect, keeps track of a total number of bytes put on the network as a result of a remote get operation, using a hardware token counter.

  5. Event-triggered control systems under packet losses

    NARCIS (Netherlands)

    Dolk, V.S.; Heemels, W.P.M.H.

    2017-01-01

    Networked control systems (NCSs) offer many benefits in terms of increased flexibility and maintainability but might also suffer from inevitable imperfections such as packet dropouts and limited communications resources. In this paper, (static and dynamic) event-triggered control (ETC) strategies

  6. Fast Packet forwarding Engine Based on Software Circuits

    NARCIS (Netherlands)

    Makkes, M.X.; Varabanescu, A.; Laat, C. de; Meijer, R.J.

    2015-01-01

    Forwarding packets is part of the performance critical path of routing devices, and affects the network performance at any scale. This operation is typically performed by dedicated routing boxes, which are fast, but expensive and inflexible. Recent work has shown that in many cases commodity

  7. Trade-Offs between Energy Saving and Reliability in Low Duty Cycle Wireless Sensor Networks Using a Packet Splitting Forwarding Technique

    Directory of Open Access Journals (Sweden)

    Leonardi Alessandro

    2010-01-01

    Full Text Available One of the challenging topics and design constraints in Wireless Sensor Networks (WSNs is the reduction of energy consumption because, in most application scenarios, replacement of power resources in sensor devices might be unfeasible. In order to minimize the power consumption, some nodes can be put to sleep during idle times and wake up only when needed. Although it seems the best way to limit the consumption of energy, other performance parameters such as network reliability have to be considered. In a recent paper, we introduced a new forwarding algorithm for WSNs based on a simple splitting procedure able to increase the network lifetime. The forwarding technique is based on the Chinese Remainder Theorem and exhibits very good results in terms of energy efficiency and complexity. In this paper, we intend to investigate a trade-off between energy efficiency and reliability of the proposed forwarding scheme when duty-cycling techniques are considered too.

  8. Mobile networks architecture

    CERN Document Server

    Perez, Andre

    2013-01-01

    This book explains the evolutions of architecture for mobiles and summarizes the different technologies:- 2G: the GSM (Global System for Mobile) network, the GPRS (General Packet Radio Service) network and the EDGE (Enhanced Data for Global Evolution) evolution;- 3G: the UMTS (Universal Mobile Telecommunications System) network and the HSPA (High Speed Packet Access) evolutions:- HSDPA (High Speed Downlink Packet Access),- HSUPA (High Speed Uplink Packet Access),- HSPA+;- 4G: the EPS (Evolved Packet System) network.The telephone service and data transmission are the

  9. Disk Operating System--DOS. Teacher Packet. Learning Activity Packets.

    Science.gov (United States)

    Oklahoma State Dept. of Vocational and Technical Education, Stillwater. Curriculum and Instructional Materials Center.

    The Learning Activity Packets (LAPs) contained in this manual are designed to assist the beginning user in understanding DOS (Disk Operating System). LAPs will not work with any version below DOS Version 3.0 and do not address the enhanced features of versions 4.0 or higher. These elementary activities cover only the DOS commands necessary to…

  10. Unsupervised Ensemble Anomaly Detection Using Time-Periodic Packet Sampling

    Science.gov (United States)

    Uchida, Masato; Nawata, Shuichi; Gu, Yu; Tsuru, Masato; Oie, Yuji

    We propose an anomaly detection method for finding patterns in network traffic that do not conform to legitimate (i.e., normal) behavior. The proposed method trains a baseline model describing the normal behavior of network traffic without using manually labeled traffic data. The trained baseline model is used as the basis for comparison with the audit network traffic. This anomaly detection works in an unsupervised manner through the use of time-periodic packet sampling, which is used in a manner that differs from its intended purpose — the lossy nature of packet sampling is used to extract normal packets from the unlabeled original traffic data. Evaluation using actual traffic traces showed that the proposed method has false positive and false negative rates in the detection of anomalies regarding TCP SYN packets comparable to those of a conventional method that uses manually labeled traffic data to train the baseline model. Performance variation due to the probabilistic nature of sampled traffic data is mitigated by using ensemble anomaly detection that collectively exploits multiple baseline models in parallel. Alarm sensitivity is adjusted for the intended use by using maximum- and minimum-based anomaly detection that effectively take advantage of the performance variations among the multiple baseline models. Testing using actual traffic traces showed that the proposed anomaly detection method performs as well as one using manually labeled traffic data and better than one using randomly sampled (unlabeled) traffic data.

  11. Multiwavelet packet entropy and its application in transmission line fault recognition and classification.

    Science.gov (United States)

    Liu, Zhigang; Han, Zhiwei; Zhang, Yang; Zhang, Qiaoge

    2014-11-01

    Multiwavelets possess better properties than traditional wavelets. Multiwavelet packet transformation has more high-frequency information. Spectral entropy can be applied as an analysis index to the complexity or uncertainty of a signal. This paper tries to define four multiwavelet packet entropies to extract the features of different transmission line faults, and uses a radial basis function (RBF) neural network to recognize and classify 10 fault types of power transmission lines. First, the preprocessing and postprocessing problems of multiwavelets are presented. Shannon entropy and Tsallis entropy are introduced, and their difference is discussed. Second, multiwavelet packet energy entropy, time entropy, Shannon singular entropy, and Tsallis singular entropy are defined as the feature extraction methods of transmission line fault signals. Third, the plan of transmission line fault recognition using multiwavelet packet entropies and an RBF neural network is proposed. Finally, the experimental results show that the plan with the four multiwavelet packet energy entropies defined in this paper achieves better performance in fault recognition. The performance with SA4 (symmetric antisymmetric) multiwavelet packet Tsallis singular entropy is the best among the combinations of different multiwavelet packets and the four multiwavelet packet entropies.

  12. Hunger and Development [Issue Packet].

    Science.gov (United States)

    American Freedom from Hunger Foundation, Washington, DC.

    A variety of informational materials is compiled in this issue packet concentrating on hunger and development. They have been assembled to understand the issues associated with the facts of world hunger and to try to invent new forms of action and thought necessary to find the possibilities hidden in the hunger issue. Items include: (1) a fact and…

  13. Attosecond electron wave packet interferometry

    International Nuclear Information System (INIS)

    Remetter, T.; Ruchon, T.; Johnsson, P.; Varju, K.; Gustafsson, E.

    2006-01-01

    Complete test of publication follows. The well controlled generation and characterization of attosecond XUV light pulses provide an unprecedented tool to study electron wave packets (EWPs). Here a train of attosecond pulses is used to create and study the phase of an EWP in momentum space. There is a clear analogy between electronic wave functions and optical fields. In optics, methods like SPIDER or wave front shearing interferometry, allow to measure the spectral or spatial phase of a light wave. These two methods are based on the same principle: an interferogram is produced when recombining two sheared replica of a light pulse, spectrally (SPIDER) or spatially (wave front shearing interferometry). This enables the comparison of two neighbouring different spectral or spatial slices of the original wave packet. In the experiment, a train of attosecond pulses is focused in an Argon atomic gas jet. EWPs are produced from the single XUV photon ionization of Argon atoms. If an IR beam is synchronized to the EWPs, it is possible to introduce a shear in momentum space between two consecutive s wave packets. A Velocity Map Imaging Spectrometer (VMIS) enables us to detect the interference pattern. An analysis of the interferograms will be presented leading to a conclusion about the symmetry of the studied wave packet.

  14. Dynamics of quantum wave packets

    International Nuclear Information System (INIS)

    Gosnell, T.R.; Taylor, A.J.; Rodriguez, G.; Clement, T.S.

    1998-01-01

    This is the final report of a three-year, Laboratory Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). The objective of this project was to develop ultrafast laser techniques for the creation and measurement of quantum vibrational wave packets in gas phase diatomic molecules. Moreover, the authors sought to manipulate the constitution of these wave packets in terms of harmonic-oscillator basis wavefunctions by manipulating the time-dependent amplitude and phase of the incident ultrashort laser pulse. They specifically investigated gaseous diatomic potassium (K 2 ), and discovered variations in the shape of the wave packets as a result of changing the linear chirp in the ultrashort preparation pulse. In particular, they found evidence for wave-packet compression for a specific degree of chirp. Important ancillary results include development of new techniques for denoising and deconvolution of femtosecond time traces and techniques for diagnosing the phase and amplitude of the electric field of femtosecond laser pulses

  15. Trade Related Reading Packets for Disabled Readers.

    Science.gov (United States)

    Davis, Beverly; Woodruff, Nancy S.

    Six trade-related reading packets for disabled readers are provided for these trades: assemblers, baking, building maintenance, data entry, interior landscaping, and warehousing. Each packet stresses from 9 to 14 skills. Those skills common to most packets include context clues, fact or opinion, details, following directions, main idea,…

  16. I/O routing in a multidimensional torus network

    Science.gov (United States)

    Chen, Dong; Eisley, Noel A.; Heidelberger, Philip

    2018-04-24

    A method, system and computer program product are disclosed for routing data packet in a computing system comprising a multidimensional torus compute node network including a multitude of compute nodes, and an I/O node network including a plurality of I/O nodes. In one embodiment, the method comprises assigning to each of the data packets a destination address identifying one of the compute nodes; providing each of the data packets with a toio value; routing the data packets through the compute node network to the destination addresses of the data packets; and when each of the data packets reaches the destination address assigned to said each data packet, routing said each data packet to one of the I/O nodes if the toio value of said each data packet is a specified value. In one embodiment, each of the data packets is also provided with an ioreturn value used to route the data packets through the compute node network.

  17. Effective Packet Number for 5G IM WeChat Application at Early Stage Traffic Classification

    Directory of Open Access Journals (Sweden)

    Muhammad Shafiq

    2017-01-01

    Full Text Available Accurate network traffic classification at early stage is very important for 5G network applications. During the last few years, researchers endeavored hard to propose effective machine learning model for classification of Internet traffic applications at early stage with few packets. Nevertheless, this essential problem still needs to be studied profoundly to find out effective packet number as well as effective machine learning (ML model. In this paper, we tried to solve the above-mentioned problem. For this purpose, five Internet traffic datasets are utilized. Initially, we extract packet size of 20 packets and then mutual information analysis is carried out to find out the mutual information of each packet on n flow type. Thereafter, we execute 10 well-known machine learning algorithms using crossover classification method. Two statistical analysis tests, Friedman and Wilcoxon pairwise tests, are applied for the experimental results. Moreover, we also apply the statistical tests for classifiers to find out effective ML classifier. Our experimental results show that 13–19 packets are the effective packet numbers for 5G IM WeChat application at early stage network traffic classification. We also find out effective ML classifier, where Random Forest ML classifier is effective classifier at early stage Internet traffic classification.

  18. Multiwavelet packets and frame packets of L2( d)

    Indian Academy of Sciences (India)

    Springer Verlag Heidelberg #4 2048 1996 Dec 15 10:16:45

    For a nice exposition of wavelet packets of L2( ) with dilation 2, see [11]. ..... p∈ d hr lm(ξ)cjp. {. ∑ q∈ d. ˆϕm(ξ + 2qπ) ˆϕj (ξ + 2qπ). } ·e−i〈k,Bξ〉 e i〈p, ξ〉 dξ ...... [14] Rudin W, Fourier Analysis on Groups (New York: John Wiley and Sons) (1962).

  19. Packet Payload Monitoring for Internet Worm Content Detection Using Deterministic Finite Automaton with Delayed Dictionary Compression

    Directory of Open Access Journals (Sweden)

    Divya Selvaraj

    2014-01-01

    Full Text Available Packet content scanning is one of the crucial threats to network security and network monitoring applications. In monitoring applications, payload of packets in a network is matched against the set of patterns in order to detect attacks like worms, viruses, and protocol definitions. During network transfer, incoming and outgoing packets are monitored in depth to inspect the packet payload. In this paper, the regular expressions that are basically string patterns are analyzed for packet payloads in detecting worms. Then the grouping scheme for regular expression matching is rewritten using Deterministic Finite Automaton (DFA. DFA achieves better processing speed during regular expression matching. DFA requires more memory space for each state. In order to reduce memory utilization, decompression technique is used. Delayed Dictionary Compression (DDC is applied for achieving better speeds in the communication links. DDC achieves decoding latency during compression of payload packets in the network. Experimental results show that the proposed approach provides better time consumption and memory utilization during detection of Internet worm attacks.

  20. Random Shift and XOR of Unequal-sized Packets (RaSOR) to Shave off Transmission Overhead

    DEFF Research Database (Denmark)

    Taghouti, Maroua; Roetter, Daniel Enrique Lucani; Fitzek, Frank Hanns Paul

    2017-01-01

    We propose the design of a novel coding scheme of unequal-sized packets. Unlike the conventional wisdom that consists of brute-force zero-padding in Random Linear Network Coding (RLNC), we exploit this heterogeneity to shave off this trailing overhead and transmit considerably less coded packets....

  1. Application of Cisco Packet Trace in the Inter-VLAN Communication Teaching%浅析Cisco Packet Tracer在Vlan间通信教学的应用

    Institute of Scientific and Technical Information of China (English)

    郑耿凡

    2014-01-01

    Cisco Packet Tracer is a network simulation platform developed by Cisco Company. And Cisco packet tracer 5.3 allows three layer switch vlan communication in the experimental teaching. Real equipment is replaced by the analog simulation software, which solves the problem of lacking teaching experimental equipment in practice and im-proves the quality of teaching.%Cisco packet tracer是由思科公司开发的一个网络模拟辅助平台,在实验教学中可以借助Cisco packet tracer5.3实现三层交换机Vlan间通信,通过模拟防真软件来代替现实的设备,以解决在实践教学中实验设备缺乏的问题,提高教学质量。

  2. An integrated circuit/packet switched video conferencing system

    International Nuclear Information System (INIS)

    Kippenhan Junior, H.A.; Lidinsky, W.P.; Roediger, G.A.; Waits, T.A.

    1996-01-01

    The HEP Network Resource Center (HEPNRC) at Fermilab and the Collider Detector Facility (CDF) collaboration have evolved a flexible, cost-effective, widely accessible video conferencing system for use by high energy physics collaborations and others wishing to use video conferencing. No current systems seemed to fully meet the needs of high energy physics collaborations. However, two classes of video conferencing technology: circuit-switched and packet-switched, if integrated, might encompass most of HEPS's needs. It was also realized that, even with this integration, some additional functions were needed and some of the existing functions were not always wanted. HEPNRC with the help of members of the CDF collaboration set out to develop such an integrated system using as many existing subsystems and components as possible. This system is called VUPAC (Video conferencing Using Packets and Circuits). This paper begins with brief descriptions of the circuit-switched and packet-switched video conferencing systems. Following this, issues and limitations of these systems are considered. Next the VUPAC system is described. Integration is accomplished primarily by a circuit/packet video conferencing interface. Augmentation is centered in another subsystem called MSB (Multiport MultiSession Bridge). Finally, there is a discussion of the future work needed in the evolution of this system. (author)

  3. An integrated circuit/packet switched video conferencing system

    Energy Technology Data Exchange (ETDEWEB)

    Kippenhan Junior, H.A.; Lidinsky, W.P.; Roediger, G.A. [Fermi National Accelerator Lab., Batavia, IL (United States). HEP Network Resource Center; Waits, T.A. [Rutgers Univ., Piscataway, NJ (United States). Dept. of Physics and Astronomy

    1996-07-01

    The HEP Network Resource Center (HEPNRC) at Fermilab and the Collider Detector Facility (CDF) collaboration have evolved a flexible, cost-effective, widely accessible video conferencing system for use by high energy physics collaborations and others wishing to use video conferencing. No current systems seemed to fully meet the needs of high energy physics collaborations. However, two classes of video conferencing technology: circuit-switched and packet-switched, if integrated, might encompass most of HEPS's needs. It was also realized that, even with this integration, some additional functions were needed and some of the existing functions were not always wanted. HEPNRC with the help of members of the CDF collaboration set out to develop such an integrated system using as many existing subsystems and components as possible. This system is called VUPAC (Video conferencing Using Packets and Circuits). This paper begins with brief descriptions of the circuit-switched and packet-switched video conferencing systems. Following this, issues and limitations of these systems are considered. Next the VUPAC system is described. Integration is accomplished primarily by a circuit/packet video conferencing interface. Augmentation is centered in another subsystem called MSB (Multiport MultiSession Bridge). Finally, there is a discussion of the future work needed in the evolution of this system. (author)

  4. Effect of latency and packet loss on achievable bandwidth

    CERN Multimedia

    CERN. Geneva

    2015-01-01

    Following an incident with a slow database replication between CERN's data centers, we discovered that even a very low rate packet loss in the network can induce significant penalties to long distance single stream TCP transfers. We explore the behaviour of multiple congestion control algorithms in a controlled loss environment in order to understand what is the achievable throughput of TCP data transfers between the Meyrin and Wigner data centres.

  5. Mitigating Receiver’s Buffer Blocking by Delay Aware Packet Scheduling in Multipath Data Transfer

    OpenAIRE

    Sarwar, Golam; Boreli, Roksana; Lochin, Emmanuel; Mifdaoui, Ahlem; Smith, Guillaume

    2013-01-01

    Reliable in-order multi-path data transfer under asymmetric heterogeneous network conditions has known problems related to receiver's buffer blocking, caused by out of order packet arrival. Consequently, the aggregate capacity from multiple paths, which theoretically should be available to and achievable by the multi-path transport protocol, is practically severely underutilized. Several mitigation techniques have been proposed to address this issue mostly by using various packet retransmissi...

  6. Spreading of a relativistic wave packet

    International Nuclear Information System (INIS)

    Almeida, C.; Jabs, A.

    1983-01-01

    A simple general proof that the spreading velocity of a relativistic free wave packet of the Broglie waves is limited is presented. For a wide class of packets it is confirmed that the limit is the velocity of light, and it is shown how this limit is approached when the width Δp of the wave packet in momentum space tends to infinity and the minimum width σ(t=o) in ordinary space tends to zero. (Author) [pt

  7. Fair packet scheduling in Wireless Mesh Networks

    KAUST Repository

    Nawab, Faisal; Jamshaid, Kamran; Shihada, Basem; Ho, Pin Han

    2014-01-01

    ordering of timestamps among neighboring nodes is sufficient for enforcing local fairness, subsequently leading to flow rate fairness in a multi-hop WMN. We show that TMAC can be implemented using the control frames in IEEE 802.11, and thus can be easily

  8. Hardware Accelerators Targeting a Novel Group Based Packet Classification Algorithm

    Directory of Open Access Journals (Sweden)

    O. Ahmed

    2013-01-01

    Full Text Available Packet classification is a ubiquitous and key building block for many critical network devices. However, it remains as one of the main bottlenecks faced when designing fast network devices. In this paper, we propose a novel Group Based Search packet classification Algorithm (GBSA that is scalable, fast, and efficient. GBSA consumes an average of 0.4 megabytes of memory for a 10 k rule set. The worst-case classification time per packet is 2 microseconds, and the preprocessing speed is 3 M rules/second based on an Xeon processor operating at 3.4 GHz. When compared with other state-of-the-art classification techniques, the results showed that GBSA outperforms the competition with respect to speed, memory usage, and processing time. Moreover, GBSA is amenable to implementation in hardware. Three different hardware implementations are also presented in this paper including an Application Specific Instruction Set Processor (ASIP implementation and two pure Register-Transfer Level (RTL implementations based on Impulse-C and Handel-C flows, respectively. Speedups achieved with these hardware accelerators ranged from 9x to 18x compared with a pure software implementation running on an Xeon processor.

  9. Oral Hygiene. Instructor's Packet. Learning Activity Package.

    Science.gov (United States)

    Hime, Kirsten

    This instructor's packet accompanies the learning activity package (LAP) on oral hygiene. Contents included in the packet are a time sheet, suggested uses for the LAP, an instruction sheet, final LAP reviews, a final LAP review answer key, suggested activities, additional resources (student handouts), student performance checklists for both…

  10. German Cultural Packets 13 and 14.

    Science.gov (United States)

    Atlanta Public Schools, GA.

    These German culture packets are designed to accompany A-LM Level II and include a statement of the rationale behind the unit, the objectives of the packet, the activities themselves, and a brief evaluation by the student. The activities involve the use of the basic text, the student workbook, corresponding tapes, and fellow students as partners…

  11. Grooming. Instructor's Packet. Learning Activity Package.

    Science.gov (United States)

    Stark, Pamela

    This instructor's packet accompanies the learning activity package (LAP) on grooming. Contents included in the packet are a time sheet, suggested uses for the LAP, an instruction sheet, final LAP reviews, a final LAP review answer key, suggested activities, an additional resources list, and student completion cards to issue to students as an…

  12. Transmission Delay Modeling of Packet Communication over Digital Subscriber Line

    Directory of Open Access Journals (Sweden)

    Jiri Vodrazka

    2013-01-01

    Full Text Available Certain multimedia and voice services, such as VoIP, IPTV, etc., are significantly delay sensitive and their performance is influenced by the overall transmission delay and its variance. One of the most common solutions used in access networks are xDSL lines, especially ADSL2+ or VDSL2. Although these subscriber lines also use packet communication, there are several differences and mechanisms, which influence their resulting delay. Their delay characteristics are also dependent on the individual settings of each xDSL provider, therefore we decided to investigate this area for typical commercially available lines in Czech Republic. Based on the measured values and experiments with real ADSL2+ lines we also developed a potential modeling method, which is presented in this article as well. The parameters for packet jitter based on the generalized Pareto distribution were modeled.

  13. Study of the Subjective Visibility of Packet Loss Artifacts in Decoded Video Sequences

    DEFF Research Database (Denmark)

    Korhonen, Jari

    2018-01-01

    Packet loss is a significant cause of visual impairments in video broadcasting over packet-switched networks. There are several subjective and objective video quality assessment methods focused on the overall perception of video quality. However, less attention has been paid on the visibility...... of packet loss artifacts appearing in spatially and temporally limited regions of a video sequence. In this paper, we present the results of a subjective study, using a methodology where a video sequence is displayed on a touchscreen and the users tap it in the positions where they observe artifacts. We...... also analyze the objective features derived from those artifacts, and propose different models for combining those features into an objective metric for assessing the noticeability of the artifacts. The practical results show that the proposed metric predicts visibility of packet loss impairments...

  14. Voice Quality Measuring Setup with Automatic Voice over IP Call Generator and Lawful Interception Packet Analyzer

    Directory of Open Access Journals (Sweden)

    PLEVA Matus

    Full Text Available This paper describes the packet measuring laboratory setup, which could be used also for lawful interception applications, using professional packet analyzer, Voice over IP call generator, free call server (Asterisk linux setup and appropriate software and hardware described below. This setup was used for measuring the quality of the automatically generated VoIP calls under stressed network conditions, when the call manager server was flooded with high bandwidth traffic, near the bandwidth limit of the connected switch. The call generator realizes 30 calls simultaneously and the packet capturer & analyzercould decode the VoIP traffic, extract RTP session data, automatically analyze the voice quality using standardized MOS (Mean Opinion Score values and describe also the source of the voice degradation (jitter, packet loss, codec, delay, etc..

  15. Time evolution of wave packets on nanostructures

    International Nuclear Information System (INIS)

    Prunele, E de

    2005-01-01

    Time evolution of wave packets on nanostructures is studied on the basis of a three-dimensional solvable model with singular interactions (de Prunele 1997 J. Phys. A: Math. Gen. 30 7831). In particular, methods and tools are provided to determine time independent upper bounds for the overlap of the normalized time-dependent wave packet with the time independent normalized wave packet concentrated at an arbitrarily chosen vertex of the nanosystem. The set of upper bounds referring to all initial positions of the wave packet and all overlaps are summarized in a matrix. The analytical formulation allows a detailed study for arbitrary geometrical configurations. Time evolution on truncated quasicrystalline systems has been found to be site selective, depending on the position of the initial wave packet

  16. Certain problems concerning wavelets and wavelets packets

    International Nuclear Information System (INIS)

    Siddiqi, A.H.

    1995-09-01

    Wavelets is the outcome of the synthesis of ideas that have emerged in different branches of science and technology, mainly in the last decade. The concept of wavelet packets, which are superpositions of wavelets, has been introduced a couple of years ago. They form bases which retain many properties of wavelets like orthogonality, smoothness and localization. The Walsh orthornomal system is a special case of wavelet packet. The wavelet packets provide at our disposal a library of orthonormal bases, each of which can be used to analyze a given signal of finite energy. The optimal choice is decided by the entropy criterion. In the present paper we discuss results concerning convergence, coefficients, and approximation of wavelet packets series in general and wavelets series in particular. Wavelet packet techniques for solutions of differential equations are also mentioned. (author). 117 refs

  17. Certain problems concerning wavelets and wavelets packets

    Energy Technology Data Exchange (ETDEWEB)

    Siddiqi, A H

    1995-09-01

    Wavelets is the outcome of the synthesis of ideas that have emerged in different branches of science and technology, mainly in the last decade. The concept of wavelet packets, which are superpositions of wavelets, has been introduced a couple of years ago. They form bases which retain many properties of wavelets like orthogonality, smoothness and localization. The Walsh orthornomal system is a special case of wavelet packet. The wavelet packets provide at our disposal a library of orthonormal bases, each of which can be used to analyze a given signal of finite energy. The optimal choice is decided by the entropy criterion. In the present paper we discuss results concerning convergence, coefficients, and approximation of wavelet packets series in general and wavelets series in particular. Wavelet packet techniques for solutions of differential equations are also mentioned. (author). 117 refs.

  18. Multidimensional signaling via wavelet packets

    Science.gov (United States)

    Lindsey, Alan R.

    1995-04-01

    This work presents a generalized signaling strategy for orthogonally multiplexed communication. Wavelet packet modulation (WPM) employs the basis functions from an arbitrary pruning of a full dyadic tree structured filter bank as orthogonal pulse shapes for conventional QAM symbols. The multi-scale modulation (MSM) and M-band wavelet modulation (MWM) schemes which have been recently introduced are handled as special cases, with the added benefit of an entire library of potentially superior sets of basis functions. The figures of merit are derived and it is shown that the power spectral density is equivalent to that for QAM (in fact, QAM is another special case) and hence directly applicable in existing systems employing this standard modulation. Two key advantages of this method are increased flexibility in time-frequency partitioning and an efficient all-digital filter bank implementation, making the WPM scheme more robust to a larger set of interferences (both temporal and sinusoidal) and computationally attractive as well.

  19. Downlink Transmission of Short Packets

    DEFF Research Database (Denmark)

    Trillingsgaard, Kasper Fløe; Popovski, Petar

    2017-01-01

    Cellular wireless systems rely on frame-based transmissions. The frame design is conventionally based on heuristics, consisting of a frame header and a data part. The frame header contains control information that provides pointers to the messages within the data part. In this paper, we revisit...... the principles of frame design and show the impact of the new design in scenarios that feature short data packets, which are central to various 5G and Internet of Things applications. We~treat framing for downlink transmission in an AWGN broadcast channel with $K$ users, where the sizes of the messages....... This requires changes in the way control information is sent, and it requires that the users need to spend power decoding other messages, thereby increasing the average power consumption. We~show that the common heuristic design is only one point on a curve that represents the tradeoff between latency and power...

  20. Exact analysis of Packet Reversed Packet Combining Scheme and Modified Packet Combining Scheme; and a combined scheme

    International Nuclear Information System (INIS)

    Bhunia, C.T.

    2007-07-01

    Packet combining scheme is a well defined simple error correction scheme for the detection and correction of errors at the receiver. Although it permits a higher throughput when compared to other basic ARQ protocols, packet combining (PC) scheme fails to correct errors when errors occur in the same bit locations of copies. In a previous work, a scheme known as Packet Reversed Packet Combining (PRPC) Scheme that will correct errors which occur at the same bit location of erroneous copies, was studied however PRPC does not handle a situation where a packet has more than 1 error bit. The Modified Packet Combining (MPC) Scheme that can correct double or higher bit errors was studied elsewhere. Both PRPC and MPC schemes are believed to offer higher throughput in previous studies, however neither adequate investigation nor exact analysis was done to substantiate this claim of higher throughput. In this work, an exact analysis of both PRPC and MPC is carried out and the results reported. A combined protocol (PRPC and MPC) is proposed and the analysis shows that it is capable of offering even higher throughput and better error correction capability at high bit error rate (BER) and larger packet size. (author)

  1. Minimizing The Completion Time Of A Wireless Cooperative Network Using Network Coding

    DEFF Research Database (Denmark)

    Roetter, Daniel Enrique Lucani; Khamfroush, Hana; Barros, João

    2013-01-01

    We consider the performance of network coding for a wireless cooperative network in which a source wants to transmit M data packets to two receivers. We assume that receivers can share their received packets with each other or simply wait to receive the packets from the source. The problem of fin...

  2. Modelling the Probability Density Function of IPTV Traffic Packet Delay Variation

    Directory of Open Access Journals (Sweden)

    Michal Halas

    2012-01-01

    Full Text Available This article deals with modelling the Probability density function of IPTV traffic packet delay variation. The use of this modelling is in an efficient de-jitter buffer estimation. When an IP packet travels across a network, it experiences delay and its variation. This variation is caused by routing, queueing systems and other influences like the processing delay of the network nodes. When we try to separate these at least three types of delay variation, we need a way to measure these types separately. This work is aimed to the delay variation caused by queueing systems which has the main implications to the form of the Probability density function.

  3. Analysis of the backpressure effect of an Organic Rankine Cycle (ORC) evaporator on the exhaust line of a turbocharged heavy duty diesel power generator for marine applications

    International Nuclear Information System (INIS)

    Michos, Constantine N.; Lion, Simone; Vlaskos, Ioannis; Taccani, Rodolfo

    2017-01-01

    Highlights: • Waste heat recovery on internal combustion engines is studied. • The backpressure effect of the Organic Rankine Cycle boiler has been evaluated. • Three different state-of-the art turbocharging technologies have been assessed. • Six different fluids for medium-high temperature recovery have been considered. • A reduction up to 10% in fuel consumption can be achieved. - Abstract: In marine and power generation sectors, waste heat recovery technologies are attracting growing attention in order to increase heavy duty diesel engines efficiency and decrease fuel consumption, with the purpose of respecting stringent emissions legislations. In this work, the backpressure effect of an Organic Rankine Cycle (ORC) evaporator on the exhaust line of a turbocharged, V12 heavy duty diesel engine, for typical marine and power generation applications has been investigated using the commercial software Ricardo WAVE. Three different state-of-the art turbocharging strategies are assessed in order to counterbalance the increased pumping losses of the engine due to the boiler installation: fixed turbine, Waste-Gate (WG) and Variable Geometry Turbine (VGT). At the same time, the steady-state thermodynamic performance of two different ORC configurations, simple tail-pipe evaporator and recuperated simple tail-pipe evaporator layouts, are assessed, with the scope of further increasing the engine power output, recovering unutilized exhaust gas heat. Several different working fluids, suitable for medium-high temperature waste heat recovery, are evaluated and screened, considering, as well, health and safety issues. Thermodynamic cycle parameters such as, for example, evaporation and condensing pressures, working fluid mass flow and cycle temperatures, are optimized in order to obtain the maximum improvement in Brake Specific Fuel Consumption (bsfc). From the engine side point of view, a VGT turbocharger is the most favorable solution to withstand increased

  4. Effects of valve timing, valve lift and exhaust backpressure on performance and gas exchanging of a two-stroke GDI engine with overhead valves

    International Nuclear Information System (INIS)

    Dalla Nora, Macklini; Lanzanova, Thompson Diórdinis Metzka; Zhao, Hua

    2016-01-01

    Highlights: • Two-stroke operation was achieved in a four-valve direct injection gasoline engine. • Shorter valve opening durations improved torque at lower engine speeds. • The longer the valve opening duration, the lower was the air trapping efficiency. • Higher exhaust backpressure and lower valve lift reduced the compressor work. - Abstract: The current demand for fuel efficient and lightweight powertrains, particularly for application in downsized and hybrid electric vehicles, has renewed the interest in two-stroke engines. In this framework, an overhead four-valve spark-ignition gasoline engine was modified to run in the two-stroke cycle. The scavenging process took place during a long valve overlap period around bottom dead centre at each crankshaft revolution. Boosted intake air was externally supplied at a constant pressure and gasoline was directly injected into the cylinder after valve closure. Intake and exhaust valve timings and lifts were independently varied through an electrohydraulic valve train, so their effects on engine performance and gas exchanging were investigated at 800 rpm and 2000 rpm. Different exhaust backpressures were also evaluated by means of exhaust throttling. Air trapping efficiency, charging efficiency and scavenge ratio were calculated based on air and fuel flow rates, and exhaust oxygen concentration at fuel rich conditions. The results indicated that longer intake and exhaust valve opening durations increased the charge purity and hence torque at higher engine speeds. At lower speeds, although, shorter valve opening durations increased air trapping efficiency and reduced the estimated supercharger power consumption due to lower air short-circuiting. A strong correlation was found between torque and charging efficiency, while air trapping efficiency was more associated to exhaust valve opening duration. The application of exhaust backpressure, as well as lower intake/exhaust valve lifts, made it possible to increase

  5. Q FUNCTION AWARE OPTICAL PACKET SWITCH WITH LOW PACKET LOSS RATE

    Directory of Open Access Journals (Sweden)

    OMPAL SINGH

    2017-03-01

    Full Text Available Optical packet switching (OPS is a very promising technology for the next generation data transfer due to the very large bandwidth of the optical fiber. The success of the OPS relies heavily on design of the node architecture which supports comparatively larger buffering capacity without detiorating signal quality too much and it should provide very low packet loss probability with reasonably low average delay. In this paper, a design analysis of low complexity OPS node architecture is discussed along-with its advantages. The presented architecture support both fixed and variable length packets. The packets are stored in a single piece of fiber using the WDM technology. Physical layer analysis presented in this paper is to obtain the Q function (Bit Error Rate. Finally, the Monte Carlo simulation is done to obtain the packet loss. The average delay performance of the switch and effect of Q values on packet loss rates are discussed.

  6. Data Aggregation and Packet Bundling of Uplink Small Packets for Monitoring Applications in LTE

    DEFF Research Database (Denmark)

    Kim, Dong Min; Sørensen, René Brandborg; Mahmood, Kashif

    2017-01-01

    topic. In this article we analyze the deployment scenarios in which aggregators can perform cellular access on behalf of multiple MTC devices. We study the effect of packet bundling at the aggregator, which alleviates overhead and resource waste when sending small packets. The aggregators give rise...... of aggregators and packet bundle size. Our results show that, in general, data aggregation can benefit the uplink massive MTC in LTE by reducing the signaling overhead....

  7. Revivals of quantum wave packets in graphene

    International Nuclear Information System (INIS)

    Krueckl, Viktor; Kramer, Tobias

    2009-01-01

    We investigate the propagation of wave packets on graphene in a perpendicular magnetic field and the appearance of collapses and revivals in the time evolution of an initially localized wave packet. The wave-packet evolution in graphene differs drastically from the one in an electron gas and shows a rich revival structure similar to the dynamics of highly excited Rydberg states. We present a novel numerical wave-packet propagation scheme in order to solve the effective single-particle Dirac-Hamiltonian of graphene and show how the collapse and revival dynamics is affected by the presence of disorder. Our effective numerical method is of general interest for the solution of the Dirac equation in the presence of potentials and magnetic fields.

  8. Dispersionless wave packets in Dirac materials

    International Nuclear Information System (INIS)

    Jakubský, Vít; Tušek, Matěj

    2017-01-01

    We show that a wide class of quantum systems with translational invariance can host dispersionless, soliton-like, wave packets. We focus on the setting where the effective, two-dimensional Hamiltonian acquires the form of the Dirac operator. The proposed framework for construction of the dispersionless wave packets is illustrated on silicene-like systems with topologically nontrivial effective mass. Our analytical predictions are accompanied by a numerical analysis and possible experimental realizations are discussed.

  9. On the theory of wave packets

    International Nuclear Information System (INIS)

    Naumov, D.V.

    2013-01-01

    In this paper we discuss some aspects of the theory of wave packets. We consider a popular non-covariant Gaussian model used in various applications and show that it predicts too slow a longitudinal dispersion rate for relativistic particles. We revise this approach by considering a covariant model of Gaussian wave packets, and examine our results by inspecting a wave packet of an arbitrary form. A general formula for the time dependence of the dispersion of a wave packet of an arbitrary form is found. Finally, we give a transparent interpretation of the disappearance of the wave function over time due to the dispersion - a feature often considered undesirable, but which is unavoidable for wave packets. We find, starting with simple examples, proceeding with their generalizations and finally by considering the continuity equation, that the integral over time of both the flux and probability densities is asymptotically proportional to the factor 1/|x| 2 in the rest frame of the wave packet, just as in the case of an ensemble of classical particles

  10. Integrated Fractional Load and Packet Scheduling for OFDMA Systems

    DEFF Research Database (Denmark)

    Monghal, Guillaume Damien; Kumar, S.; Pedersen, Klaus I.

    2009-01-01

    This paper study the performance of an orthogonal frequency division multiple access (OFDMA) system under fractional load based in long term evolution (LTE) downlink. Fractional load is defined by a situation where only a fraction of the bandwidth is used for transmission due to lack of traffic....... This type of situation should result in a global increase of signal to interference and noise ratio (SINR) conditions in the network. We propose different methods integrating the transmission pattern selection to the packet scheduling functionality of the enode-B depending only on the channel quality...

  11. On-the-fly Packet Error Recovery in a Cooperative Cluster of Mobile Devices

    DEFF Research Database (Denmark)

    Vingelmann, Peter; Heide, Janus; Pedersen, Morten Videbæk

    2011-01-01

    This paper investigates the possibility of packet error recovery in a cooperative cluster of mobile devices. We assume that these devices receive data from a broadcast transmission on their primary network interface (e.g. LTE network), and they are using a secondary network interface (e.g. ad hoc....... We also introduce a demo application that implements this technique on Nokia phones. Then we present our testbed and the collected measurement results in order to evaluate the performance of our protocol....

  12. Collective network routing

    Science.gov (United States)

    Hoenicke, Dirk

    2014-12-02

    Disclosed are a unified method and apparatus to classify, route, and process injected data packets into a network so as to belong to a plurality of logical networks, each implementing a specific flow of data on top of a common physical network. The method allows to locally identify collectives of packets for local processing, such as the computation of the sum, difference, maximum, minimum, or other logical operations among the identified packet collective. Packets are injected together with a class-attribute and an opcode attribute. Network routers, employing the described method, use the packet attributes to look-up the class-specific route information from a local route table, which contains the local incoming and outgoing directions as part of the specifically implemented global data flow of the particular virtual network.

  13. A Hybrid CPU/GPU Pattern-Matching Algorithm for Deep Packet Inspection.

    Directory of Open Access Journals (Sweden)

    Chun-Liang Lee

    Full Text Available The large quantities of data now being transferred via high-speed networks have made deep packet inspection indispensable for security purposes. Scalable and low-cost signature-based network intrusion detection systems have been developed for deep packet inspection for various software platforms. Traditional approaches that only involve central processing units (CPUs are now considered inadequate in terms of inspection speed. Graphic processing units (GPUs have superior parallel processing power, but transmission bottlenecks can reduce optimal GPU efficiency. In this paper we describe our proposal for a hybrid CPU/GPU pattern-matching algorithm (HPMA that divides and distributes the packet-inspecting workload between a CPU and GPU. All packets are initially inspected by the CPU and filtered using a simple pre-filtering algorithm, and packets that might contain malicious content are sent to the GPU for further inspection. Test results indicate that in terms of random payload traffic, the matching speed of our proposed algorithm was 3.4 times and 2.7 times faster than those of the AC-CPU and AC-GPU algorithms, respectively. Further, HPMA achieved higher energy efficiency than the other tested algorithms.

  14. Survival of the Fittest: An Active Queue Management Technique for Noisy Packet Flows

    Directory of Open Access Journals (Sweden)

    Shirish S. Karande

    2007-01-01

    Full Text Available We present a novel active queue management (AQM technique to demonstrate the efficacy of practically harnessing the predictive utility of SSR indications for improved video communication. We consider a network within which corrupted packets are relayed over multiple hops, but a certain percentage of packets needs to be dropped at an intermediate node due to congestion. We propose an AQM technique, survival of the fittest (SOTF, to be employed at the relay node, within which we use packet state information, available from SSR indications and checksums, to drop packets with the highest corruption levels. On the basis of actual 802.11b measurements we show that such a side information (SI aware processing within the network can provide significant performance benefits over an SI-unaware scheme, random queue management (RQM, which is forced to randomly discard packets. With trace-based simulations, we show the utility of the proposed AQM technique in improving the error recovery performance of cross-layer FEC schemes. Finally, with the help of H.264-based video simulations these improvements are shown to translate into a significant improvement in video quality.

  15. Effects of wireless packet loss in industrial process control systems.

    Science.gov (United States)

    Liu, Yongkang; Candell, Richard; Moayeri, Nader

    2017-05-01

    Timely and reliable sensing and actuation control are essential in networked control. This depends on not only the precision/quality of the sensors and actuators used but also on how well the communications links between the field instruments and the controller have been designed. Wireless networking offers simple deployment, reconfigurability, scalability, and reduced operational expenditure, and is easier to upgrade than wired solutions. However, the adoption of wireless networking has been slow in industrial process control due to the stochastic and less than 100% reliable nature of wireless communications and lack of a model to evaluate the effects of such communications imperfections on the overall control performance. In this paper, we study how control performance is affected by wireless link quality, which in turn is adversely affected by severe propagation loss in harsh industrial environments, co-channel interference, and unintended interference from other devices. We select the Tennessee Eastman Challenge Model (TE) for our study. A decentralized process control system, first proposed by N. Ricker, is adopted that employs 41 sensors and 12 actuators to manage the production process in the TE plant. We consider the scenario where wireless links are used to periodically transmit essential sensor measurement data, such as pressure, temperature and chemical composition to the controller as well as control commands to manipulate the actuators according to predetermined setpoints. We consider two models for packet loss in the wireless links, namely, an independent and identically distributed (IID) packet loss model and the two-state Gilbert-Elliot (GE) channel model. While the former is a random loss model, the latter can model bursty losses. With each channel model, the performance of the simulated decentralized controller using wireless links is compared with the one using wired links providing instant and 100% reliable communications. The sensitivity of the

  16. nDPI: Open-Source High-Speed Deep Packet Inspection

    DEFF Research Database (Denmark)

    Deri, Luca; Martinelli, Maurizio; Bujlow, Tomasz

    2014-01-01

    protocols became increasingly challenging, thus creating a motivation for creating tools and libraries for network protocol classification. This paper covers the design and implementation of nDPI, an open-source library for protocol classification using both packet header and payload. nDPI was extensively...

  17. Implementation of fast handover for proxy mobile IPv6: Resolving out-of-order packets.

    Science.gov (United States)

    Kang, Byungseok; Anh, Khuong Quoc; Choo, Hyunseung

    2017-01-01

    Mobile IP allows for location-independent routing of IP datagrams on the Internet. Mobile IP specifies how a mobile node (MN) registers with its home agent and how the home agent routes datagrams to the MN through the tunnel. Current Mobile IP protocols have difficulties meeting the stringent handover delay requirements of future wireless networks. Fast handover for Proxy Mobile IPv6 (FPMIPv6) is used to resolve handover latency and packet loss problems that occur in the Proxy Mobile IPv6 (PMIPv6) protocol. However, while implementing the FPMIPv6 scheme in a testbed, we encounter the out-of-order packet (OoOP) problem. The cause of this problem is the existence of two paths for data transmitted from a correspondent node (CN) to an MN. Since the problem affects the quality of service (QoS) of the network and the performance of the MN, we propose a new scheme using the last packet marker and packet buffering to solve this problem in FPMIPv6. The new Mobile Access Gateway (MAG) can control and deliver the data transmitted via the old path or the new path to an MN in order, using the last packet marker to notify the end of the data delivery in the old path and the packet buffering for holding the data delivered in the new path. We implement both the proposed scheme and FPMIPv6 in a testbed as a real network environment to demonstrate the correctness, cost effectiveness, and performance of the proposed scheme. A performance evaluation reveals that the proposed scheme can handle the OoOP problem efficiently.

  18. Implementation of fast handover for proxy mobile IPv6: Resolving out-of-order packets.

    Directory of Open Access Journals (Sweden)

    Byungseok Kang

    Full Text Available Mobile IP allows for location-independent routing of IP datagrams on the Internet. Mobile IP specifies how a mobile node (MN registers with its home agent and how the home agent routes datagrams to the MN through the tunnel. Current Mobile IP protocols have difficulties meeting the stringent handover delay requirements of future wireless networks. Fast handover for Proxy Mobile IPv6 (FPMIPv6 is used to resolve handover latency and packet loss problems that occur in the Proxy Mobile IPv6 (PMIPv6 protocol. However, while implementing the FPMIPv6 scheme in a testbed, we encounter the out-of-order packet (OoOP problem. The cause of this problem is the existence of two paths for data transmitted from a correspondent node (CN to an MN. Since the problem affects the quality of service (QoS of the network and the performance of the MN, we propose a new scheme using the last packet marker and packet buffering to solve this problem in FPMIPv6. The new Mobile Access Gateway (MAG can control and deliver the data transmitted via the old path or the new path to an MN in order, using the last packet marker to notify the end of the data delivery in the old path and the packet buffering for holding the data delivered in the new path. We implement both the proposed scheme and FPMIPv6 in a testbed as a real network environment to demonstrate the correctness, cost effectiveness, and performance of the proposed scheme. A performance evaluation reveals that the proposed scheme can handle the OoOP problem efficiently.

  19. High Angular Momentum Rydberg Wave Packets

    Science.gov (United States)

    Wyker, Brendan

    2011-12-01

    High angular momentum Rydberg wave packets are studied. Application of carefully tailored electric fields to low angular momentum, high- n (n ˜ 300) Rydberg atoms creates coherent superpositions of Stark states with near extreme values of angular momentum, ℓ. Wave packet components orbit the parent nucleus at rates that depend on their energy, leading to periods of localization and delocalization as the components come into and go out of phase with each other. Monitoring survival probability signals in the presence of position dependent probing leads to observation of characteristic oscillations based on the composition of the wave packet. The discrete nature of electron energy levels is observed through the measurement of quantum revivals in the wave packet localization signal. Time-domain spectroscopy of these signals allows determination of both the population and phase of individual superposition components. Precise manipulation of wave packets is achieved through further application of pulsed electric fields. Decoherence effects due to background gas collisions and electrical noise are also detailed. Quantized classical trajectory Monte-Carlo simulations are introduced and agree remarkably well with experimental results.

  20. Parametric packet-based audiovisual quality model for IPTV services

    CERN Document Server

    Garcia, Marie-Neige

    2014-01-01

    This volume presents a parametric packet-based audiovisual quality model for Internet Protocol TeleVision (IPTV) services. The model is composed of three quality modules for the respective audio, video and audiovisual components. The audio and video quality modules take as input a parametric description of the audiovisual processing path, and deliver an estimate of the audio and video quality. These outputs are sent to the audiovisual quality module which provides an estimate of the audiovisual quality. Estimates of perceived quality are typically used both in the network planning phase and as part of the quality monitoring. The same audio quality model is used for both these phases, while two variants of the video quality model have been developed for addressing the two application scenarios. The addressed packetization scheme is MPEG2 Transport Stream over Real-time Transport Protocol over Internet Protocol. In the case of quality monitoring, that is the case for which the network is already set-up, the aud...

  1. Ad hoc networking scheme for mobile cyber-physical systems

    KAUST Repository

    Bader, Ahmed; Alouini, Mohamed-Slim

    2017-01-01

    Embodiments of the present disclosure provide techniques for packet routing. In an embodiment, when a transmitting communication device injects a packet into a communication network, a receiving communication device that is closer to a sink

  2. Priority-based methods for reducing the impact of packet loss on HEVC encoded video streams

    Science.gov (United States)

    Nightingale, James; Wang, Qi; Grecos, Christos

    2013-02-01

    The rapid growth in the use of video streaming over IP networks has outstripped the rate at which new network infrastructure has been deployed. These bandwidth-hungry applications now comprise a significant part of all Internet traffic and present major challenges for network service providers. The situation is more acute in mobile networks where the available bandwidth is often limited. Work towards the standardisation of High Efficiency Video Coding (HEVC), the next generation video coding scheme, is currently on track for completion in 2013. HEVC offers the prospect of a 50% improvement in compression over the current H.264 Advanced Video Coding standard (H.264/AVC) for the same quality. However, there has been very little published research on HEVC streaming or the challenges of delivering HEVC streams in resource-constrained network environments. In this paper we consider the problem of adapting an HEVC encoded video stream to meet the bandwidth limitation in a mobile networks environment. Video sequences were encoded using the Test Model under Consideration (TMuC HM6) for HEVC. Network abstraction layers (NAL) units were packetized, on a one NAL unit per RTP packet basis, and transmitted over a realistic hybrid wired/wireless testbed configured with dynamically changing network path conditions and multiple independent network paths from the streamer to the client. Two different schemes for the prioritisation of RTP packets, based on the NAL units they contain, have been implemented and empirically compared using a range of video sequences, encoder configurations, bandwidths and network topologies. In the first prioritisation method the importance of an RTP packet was determined by the type of picture and the temporal switching point information carried in the NAL unit header. Packets containing parameter set NAL units and video coding layer (VCL) NAL units of the instantaneous decoder refresh (IDR) and the clean random access (CRA) pictures were given the

  3. Digital transceiver implementation for wavelet packet modulation

    Science.gov (United States)

    Lindsey, Alan R.; Dill, Jeffrey C.

    1998-03-01

    Current transceiver designs for wavelet-based communication systems are typically reliant on analog waveform synthesis, however, digital processing is an important part of the eventual success of these techniques. In this paper, a transceiver implementation is introduced for the recently introduced wavelet packet modulation scheme which moves the analog processing as far as possible toward the antenna. The transceiver is based on the discrete wavelet packet transform which incorporates level and node parameters for generalized computation of wavelet packets. In this transform no particular structure is imposed on the filter bank save dyadic branching, and a maximum level which is specified a priori and dependent mainly on speed and/or cost considerations. The transmitter/receiver structure takes a binary sequence as input and, based on the desired time- frequency partitioning, processes the signal through demultiplexing, synthesis, analysis, multiplexing and data determination completely in the digital domain - with exception of conversion in and out of the analog domain for transmission.

  4. Comparison between wavelet and wavelet packet transform features for classification of faults in distribution system

    Science.gov (United States)

    Arvind, Pratul

    2012-11-01

    The ability to identify and classify all ten types of faults in a distribution system is an important task for protection engineers. Unlike transmission system, distribution systems have a complex configuration and are subjected to frequent faults. In the present work, an algorithm has been developed for identifying all ten types of faults in a distribution system by collecting current samples at the substation end. The samples are subjected to wavelet packet transform and artificial neural network in order to yield better classification results. A comparison of results between wavelet transform and wavelet packet transform is also presented thereby justifying the feature extracted from wavelet packet transform yields promising results. It should also be noted that current samples are collected after simulating a 25kv distribution system in PSCAD software.

  5. Dynamic Average Consensus and Consensusability of General Linear Multiagent Systems with Random Packet Dropout

    Directory of Open Access Journals (Sweden)

    Wen-Min Zhou

    2013-01-01

    Full Text Available This paper is concerned with the consensus problem of general linear discrete-time multiagent systems (MASs with random packet dropout that happens during information exchange between agents. The packet dropout phenomenon is characterized as being a Bernoulli random process. A distributed consensus protocol with weighted graph is proposed to address the packet dropout phenomenon. Through introducing a new disagreement vector, a new framework is established to solve the consensus problem. Based on the control theory, the perturbation argument, and the matrix theory, the necessary and sufficient condition for MASs to reach mean-square consensus is derived in terms of stability of an array of low-dimensional matrices. Moreover, mean-square consensusable conditions with regard to network topology and agent dynamic structure are also provided. Finally, the effectiveness of the theoretical results is demonstrated through an illustrative example.

  6. SIMULASI JARINGAN KOMPUTER MENGGUNAKAN CISCO PACKET TRACER

    Directory of Open Access Journals (Sweden)

    M Mufadhol

    2012-01-01

    Full Text Available Perkembangan jaringan komputer saat ini begitu pesat, monitoring jaringan komputer akan menjadi suatu hal yang sulit dan rumit. Koneksi jaringan komputer merupakan suatu hal yang mendasar dalam suatu jaringan, karena bila koneksi itu bermasalah maka semua jenis aplikasi yang dijalankan melalui jaringan komputer tidak dapat digunakan. Cisco packet tracer dapat digunakan untuk simulasi yang mencerminkan arsitektur dan juga model dari jaringan komputer pada sistem jaringan yang digunakan. Dengan menggunakan aplikasi cisco packet tracer, simulasi mengenai jaringan dapat dimanfaatkan menjadi informasi tentang keadaan koneksi komputer dalam suatu jaringan.

  7. On the fly all-optical packet switching based on hybrid WDM/OCDMA labeling scheme

    Science.gov (United States)

    Brahmi, Houssem; Giannoulis, Giannis; Menif, Mourad; Katopodis, Vasilis; Kalavrouziotis, Dimitrios; Kouloumentas, Christos; Groumas, Panos; Kanakis, Giannis; Stamatiadis, Christos; Avramopoulos, Hercules; Erasme, Didier

    2014-02-01

    We introduce a novel design of an all-optical packet routing node that allows for the selection and forwarding of optical packets based on the routing information contained in hybrid wavelength division multiplexing/optical code division multiple access (WDM/OCDMA) labels. A stripping paradigm of optical code-label is adopted. The router is built around an optical-code gate that consists in an optical flip-flop controlled by two fiber Bragg grating correlators and is combined with a Mach-Zehnder interferometer (MZI)-based forwarding gate. We experimentally verify the proof-of-principle operation of the proposed self-routing node under NRZ and OCDMA packet traffic conditions. The successful switching of elastic NRZ payload at 40 Gb/s controlled by DS-OCDMA coded labels and the forwarding operation of encoded data using EQC codes are presented. Proper auto-correlation functions are obtained with higher than 8.1 dB contrast ratio, suitable to efficiently trigger the latching device with a contrast ratio of 11.6 dB and switching times below 3.8 ns. Error-free operation is achieved with 1.5 dB penalty for 40 Gb/s NRZ data and with 2.1 dB penalty for DS-OCDMA packets. The scheme can further be applied to large-scale optical packet switching networks by exploiting efficient optical coders allocated at different WDM channels.

  8. Design of Packet-Based Block Codes with Shift Operators

    Directory of Open Access Journals (Sweden)

    Jacek Ilow

    2010-01-01

    Full Text Available This paper introduces packet-oriented block codes for the recovery of lost packets and the correction of an erroneous single packet. Specifically, a family of systematic codes is proposed, based on a Vandermonde matrix applied to a group of k information packets to construct r redundant packets, where the elements of the Vandermonde matrix are bit-level right arithmetic shift operators. The code design is applicable to packets of any size, provided that the packets within a block of k information packets are of uniform length. In order to decrease the overhead associated with packet padding using shift operators, non-Vandermonde matrices are also proposed for designing packet-oriented block codes. An efficient matrix inversion procedure for the off-line design of the decoding algorithm is presented to recover lost packets. The error correction capability of the design is investigated as well. The decoding algorithm, based on syndrome decoding, to correct a single erroneous packet in a group of n=k+r received packets is presented. The paper is equipped with examples of codes using different parameters. The code designs and their performance are tested using Monte Carlo simulations; the results obtained exhibit good agreement with the corresponding theoretical results.

  9. Design of Packet-Based Block Codes with Shift Operators

    Directory of Open Access Journals (Sweden)

    Ilow Jacek

    2010-01-01

    Full Text Available This paper introduces packet-oriented block codes for the recovery of lost packets and the correction of an erroneous single packet. Specifically, a family of systematic codes is proposed, based on a Vandermonde matrix applied to a group of information packets to construct redundant packets, where the elements of the Vandermonde matrix are bit-level right arithmetic shift operators. The code design is applicable to packets of any size, provided that the packets within a block of information packets are of uniform length. In order to decrease the overhead associated with packet padding using shift operators, non-Vandermonde matrices are also proposed for designing packet-oriented block codes. An efficient matrix inversion procedure for the off-line design of the decoding algorithm is presented to recover lost packets. The error correction capability of the design is investigated as well. The decoding algorithm, based on syndrome decoding, to correct a single erroneous packet in a group of received packets is presented. The paper is equipped with examples of codes using different parameters. The code designs and their performance are tested using Monte Carlo simulations; the results obtained exhibit good agreement with the corresponding theoretical results.

  10. The Network Protocol Analysis Technique in Snort

    Science.gov (United States)

    Wu, Qing-Xiu

    Network protocol analysis is a network sniffer to capture data for further analysis and understanding of the technical means necessary packets. Network sniffing is intercepted by packet assembly binary format of the original message content. In order to obtain the information contained. Required based on TCP / IP protocol stack protocol specification. Again to restore the data packets at protocol format and content in each protocol layer. Actual data transferred, as well as the application tier.

  11. Solid Waste Activity Packet for Teachers.

    Science.gov (United States)

    Illinois Univ., Urbana. Cooperative Extension Service.

    This solid waste activity packet introduces students to the solid waste problem in Illinois. Topics explore consumer practices in the market place, packaging, individual and community garbage generation, and disposal practices. The activities provide an integrated approach to incorporating solid waste management issues into subject areas. The…

  12. Peninsula Humane Society Teacher's Packet. Secondary Level.

    Science.gov (United States)

    Peninsula Humane Society, San Mateo, CA.

    Activities in this teacher's packet are designed to familiarize secondary school students with the responsibilities involved in pet ownership. Teaching plans are provided for a total of 12 lessons grouped under social studies, language arts, math, and health sciences. Activities focus on pet overpopulation, expressions of social responses in…

  13. Biological Diversity. Global Issues Education Packet.

    Science.gov (United States)

    Holm, Amy E.

    Biological diversity, also commonly called genetic diversity, refers to the variety of organisms on Earth. Scientists are concerned that many species will become extinct because of extensive development in the tropical regions. This packet is designed to increase student's awareness about direct and indirect causes of extinction, endangered…

  14. The Control Packet Collision Avoidance Algorithm for the Underwater Multichannel MAC Protocols via Time-Frequency Masking

    Directory of Open Access Journals (Sweden)

    Yang Yu

    2016-01-01

    Full Text Available Establishing high-speed and reliable underwater acoustic networks among multiunmanned underwater vehicles (UUVs is basic to realize cooperative and intelligent control among different UUVs. Nevertheless, different from terrestrial network, the propagation speed of the underwater acoustic network is 1500 m/s, which makes the design of the underwater acoustic network MAC protocols a big challenge. In accordance with multichannel MAC protocols, data packets and control packets are transferred through different channels, which lowers the adverse effect of acoustic network and gradually becomes the popular issues of underwater acoustic networks MAC protocol research. In this paper, we proposed a control packet collision avoidance algorithm utilizing time-frequency masking to deal with the control packets collision in the control channel. This algorithm is based on the scarcity of the noncoherent underwater acoustic communication signals, which regards collision avoiding as separation of the mixtures of communication signals from different nodes. We first measure the W-Disjoint Orthogonality of the MFSK signals and the simulation result demonstrates that there exists time-frequency mask which can separate the source signals from the mixture of the communication signals. Then we present a pairwise hydrophones separation system based on deep networks and the location information of the nodes. Consequently, the time-frequency mask can be estimated.

  15. A feasibility study of stateful automaton packet inspection for streaming application detection systems

    Science.gov (United States)

    Tseng, Kuo-Kun; Lo, Jiao; Liu, Yiming; Chang, Shih-Hao; Merabti, Madjid; Ng, Felix, C. K.; Wu, C. H.

    2017-10-01

    The rapid development of the internet has brought huge benefits and social impacts; however, internet security has also become a great problem for users, since traditional approaches to packet classification cannot achieve satisfactory detection performance due to their low accuracy and efficiency. In this paper, a new stateful packet inspection method is introduced, which can be embedded in the network gateway and used by a streaming application detection system. This new detection method leverages the inexact automaton approach, using part of the header field and part of the application layer data of a packet. Based on this approach, an advanced detection system is proposed for streaming applications. The workflow of the system involves two stages: the training stage and the detection stage. In the training stage, the system initially captures characteristic patterns from a set of application packet flows. After this training is completed, the detection stage allows the user to detect the target application by capturing new application flows. This new detection approach is also evaluated using experimental analysis; the results of this analysis show that this new approach not only simplifies the management of the state detection system, but also improves the accuracy of data flow detection, making it feasible for real-world network applications.

  16. PcapDB: Search Optimized Packet Capture, Version 0.1.0.0

    Energy Technology Data Exchange (ETDEWEB)

    2016-11-04

    PcapDB is a packet capture system designed to optimize the captured data for fast search in the typical (network incident response) use case. The technology involved in this software has been submitted via the IDEAS system and has been filed as a provisional patent. It includes the following primary components: capture: The capture component utilizes existing capture libraries to retrieve packets from network interfaces. Once retrieved the packets are passed to additional threads for sorting into flows and indexing. The sorted flows and indexes are passed to other threads so that they can be written to disk. These components are written in the C programming language. search: The search components provide a means to find relevant flows and the associated packets. A search query is parsed and represented as a search tree. Various search commands, written in C, are then used resolve this tree into a set of search results. The tree generation and search execution management components are written in python. interface: The PcapDB web interface is written in Python on the Django framework. It provides a series of pages, API's, and asynchronous tasks that allow the user to manage the capture system, perform searches, and retrieve results. Web page components are written in HTML,CSS and Javascript.

  17. Congestion Control for a Fair Packet Delivery in WSN: From a Complex System Perspective

    Directory of Open Access Journals (Sweden)

    Daniela Aguirre-Guerrero

    2014-01-01

    Full Text Available In this work, we propose that packets travelling across a wireless sensor network (WSN can be seen as the active agents that make up a complex system, just like a bird flock or a fish school, for instance. From this perspective, the tools and models that have been developed to study this kind of systems have been applied. This is in order to create a distributed congestion control based on a set of simple rules programmed at the nodes of the WSN. Our results show that it is possible to adapt the carried traffic to the network capacity, even under stressing conditions. Also, the network performance shows a smooth degradation when the traffic goes beyond a threshold which is settled by the proposed self-organized control. In contrast, without any control, the network collapses before this threshold. The use of the proposed solution provides an effective strategy to address some of the common problems found in WSN deployment by providing a fair packet delivery. In addition, the network congestion is mitigated using adaptive traffic mechanisms based on a satisfaction parameter assessed by each packet which has impact on the global satisfaction of the traffic carried by the WSN.

  18. Turbulent Spot Pressure Fluctuation Wave Packet Model

    Energy Technology Data Exchange (ETDEWEB)

    Dechant, Lawrence J. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2017-05-01

    Wave packet analysis provides a connection between linear small disturbance theory and subsequent nonlinear turbulent spot flow behavior. The traditional association between linear stability analysis and nonlinear wave form is developed via the method of stationary phase whereby asymptotic (simplified) mean flow solutions are used to estimate dispersion behavior and stationary phase approximation are used to invert the associated Fourier transform. The resulting process typically requires nonlinear algebraic equations inversions that can be best performed numerically, which partially mitigates the value of the approximation as compared to a more complete, e.g. DNS or linear/nonlinear adjoint methods. To obtain a simpler, closed-form analytical result, the complete packet solution is modeled via approximate amplitude (linear convected kinematic wave initial value problem) and local sinusoidal (wave equation) expressions. Significantly, the initial value for the kinematic wave transport expression follows from a separable variable coefficient approximation to the linearized pressure fluctuation Poisson expression. The resulting amplitude solution, while approximate in nature, nonetheless, appears to mimic many of the global features, e.g. transitional flow intermittency and pressure fluctuation magnitude behavior. A low wave number wave packet models also recover meaningful auto-correlation and low frequency spectral behaviors.

  19. Performance Analysis of SINEMO: Seamless IP-diversity Based Network Mobility

    National Research Council Canada - National Science Library

    Chowdhury, Pulak K; Reaz, Abu S; Atiquzzaman, Mohammed; Ivancic, William

    2007-01-01

    ...) to support network mobility. NEMO BSP inherits all the drawbacks of Mobile IPv6, such as inefficient routing path, single point of failure, high handover latency and packet loss, and high packet overhead...

  20. Stochastic ℋ∞ Finite-Time Control of Discrete-Time Systems with Packet Loss

    Directory of Open Access Journals (Sweden)

    Yingqi Zhang

    2012-01-01

    Full Text Available This paper investigates the stochastic finite-time stabilization and ℋ∞ control problem for one family of linear discrete-time systems over networks with packet loss, parametric uncertainties, and time-varying norm-bounded disturbance. Firstly, the dynamic model description studied is given, which, if the packet dropout is assumed to be a discrete-time homogenous Markov process, the class of discrete-time linear systems with packet loss can be regarded as Markovian jump systems. Based on Lyapunov function approach, sufficient conditions are established for the resulting closed-loop discrete-time system with Markovian jumps to be stochastic ℋ∞ finite-time boundedness and then state feedback controllers are designed to guarantee stochastic ℋ∞ finite-time stabilization of the class of stochastic systems. The stochastic ℋ∞ finite-time boundedness criteria can be tackled in the form of linear matrix inequalities with a fixed parameter. As an auxiliary result, we also give sufficient conditions on the robust stochastic stabilization of the class of linear systems with packet loss. Finally, simulation examples are presented to illustrate the validity of the developed scheme.

  1. 106-17 Telemetry Standards Recorder Data Packet Format Standard Chapter 11

    Science.gov (United States)

    2017-07-01

    communication data. This packet standard will allow use of a common set of data interpretation libraries to reduce the cost of producing data analysis...controller CAN controller area network CBR constant bit rate CIU communication interface unit CSDW channel-specific data word CTS Combat Training Systems...field shall be used to indicate bus identification as follows. 111 Communication interface unit (CIU) Left Bus A 110 CIU Left Bus B 101 CIU Right Bus

  2. Decreasing the exhaust outlet temperatures on a class III bus with the lowest impact on the exhaust backpressure and the fuel consumption

    Science.gov (United States)

    Aslan, E.; Ozturk, Y.; Dileroglu, S.

    2017-07-01

    The focus of this study is to determine the most appropriate exhaust tail pipe form among three different type of designs with respect to their temperature loss efficiency for a 9.5m intercity bus equipped with an Euro VI diesel engine and an automated transmission. To provide lower temperatures at the exhaust outlet, mentioned designs were submitted on to a CFD simulation using Ansys Fluent 17.1, while for manufactured products, temperature measurement tests were conducted in an environmental chamber with Omega K-type thermocouples, and Flir T420 thermal camera was used to monitor outer surface temperature distributions to make a comparison between theoretical and practical results. In order to obtain these practical results, actual tests were performed in an environmental chamber with a constant ambient temperature during the vehicle exhaust emission system regeneration process. In conclusion, an exhaust tail pipe design with a diffuser having a circular contraction and expansion forms is designated since it was the most optimized option in terms of temperature loss efficiency, inconsiderable exhaust backpressure increase and manufacturing costs.

  3. The Evolution and Revival Structure of Localized Quantum Wave Packets

    OpenAIRE

    Bluhm, Robert; Kostelecky, Alan; Porter, James

    1995-01-01

    Localized quantum wave packets can be produced in a variety of physical systems and are the subject of much current research in atomic, molecular, chemical, and condensed-matter physics. They are particularly well suited for studying the classical limit of a quantum-mechanical system. The motion of a localized quantum wave packet initially follows the corresponding classical motion. However, in most cases the quantum wave packet spreads and undergoes a series of collapses and revivals. We pre...

  4. Microwave Ionization of an Atomic Electron Wave Packet

    International Nuclear Information System (INIS)

    Noel, Michael W.; Ko, Lung; Gallagher, T. F.

    2001-01-01

    A short microwave pulse is used to ionize a lithium Rydberg wave packet launched from the core at a well-defined phase of the field. We observe a strong dependence on the relative phase between the motion of the wave packet and the oscillations of the field. This phase dependent ionization is also studied as a function of the relative frequency. Our experimental observations are in good qualitative agreement with a one-dimensional classical model of wave packet ionization

  5. Compressed Domain Packet Loss Concealment of Sinusoidally Coded Speech

    DEFF Research Database (Denmark)

    Rødbro, Christoffer A.; Christensen, Mads Græsbøll; Andersen, Søren Vang

    2003-01-01

    We consider the problem of packet loss concealment for voice over IP (VoIP). The speech signal is compressed at the transmitter using a sinusoidal coding scheme working at 8 kbit/s. At the receiver, packet loss concealment is carried out working directly on the quantized sinusoidal parameters......, based on time-scaling of the packets surrounding the missing ones. Subjective listening tests show promising results indicating the potential of sinusoidal speech coding for VoIP....

  6. First Field Trial of Optical Label-Based Switching and Packet Drop on a 477km NTON/Sprint Link

    International Nuclear Information System (INIS)

    Hernandez, V J; Pan, Z; Cao, J; Tsui, V K; Bansal, Y; Fong, S K H; Zhang, Y; Jeon, M Y; Yoo, S J B; Bodtker, B; Bond, S; Lennon, W J; Higashi, H; Lyles, B; McDonald, R

    2001-01-01

    We demonstrate the first field trial of optical label-based wavelength switching and packet drop on 476.8km of the National Transparent Optical Network. Subcarrier multiplexed labels control a switch fabric that includes a tunable wavelength converter and arrayed waveguide grating router

  7. Asymmetric Modulation Gains in Network Coded Relay Networks

    DEFF Research Database (Denmark)

    Roetter, Daniel Enrique Lucani; Fitzek, Frank

    2015-01-01

    Wireless relays have usually been considered in two ways. On the one hand, a physical layer approach focused on per-packet reliability and involving the relay on each packet transmission. On the other, recent approaches have relied on the judicious activation of the relay at the network level to ...

  8. A time-frequency analysis of wave packet fractional revivals

    International Nuclear Information System (INIS)

    Ghosh, Suranjana; Banerji, J

    2007-01-01

    We show that the time-frequency analysis of the autocorrelation function is, in many ways, a more appropriate tool to resolve fractional revivals of a wave packet than the usual time-domain analysis. This advantage is crucial in reconstructing the initial state of the wave packet when its coherent structure is short-lived and decays before it is fully revived. Our calculations are based on the model example of fractional revivals in a Rydberg wave packet of circular states. We end by providing an analytical investigation which fully agrees with our numerical observations on the utility of time-frequency analysis in the study of wave packet fractional revivals

  9. Wave-packet revivals for quantum systems with nondegenerate energies

    International Nuclear Information System (INIS)

    Bluhm, R.; Tudose, B.

    1996-01-01

    The revival structure of wave packets is examined for quantum systems having energies that depend on two nondegenerate quantum numbers. For such systems, the evolution of the wave packet is controlled by two classical periods and three revival times. These wave packets exhibit quantum beats in the initial motion as well as new types of long-term revivals. The issue of whether fractional revivals can form is addressed. We present an analytical proof showing that at certain times equal to rational fractions of the revival times the wave packet can reform as a sum of subsidiary waves and that both conventional and new types of fractional revivals can occur. (orig.)

  10. Dispersionless wave packets in Dirac materials

    Czech Academy of Sciences Publication Activity Database

    Jakubský, Vít; Tušek, M.

    2017-01-01

    Roč. 378, MAR (2017), s. 171-182 ISSN 0003-4916 R&D Projects: GA ČR(CZ) GJ15-07674Y; GA ČR GA17-01706S Institutional support: RVO:61389005 Keywords : quantum systems * wave packets * dispersion * dirac materials Subject RIV: BE - Theoretical Physics OBOR OECD: Atomic, molecular and chemical physics ( physics of atoms and molecules including collision, interaction with radiation, magnetic resonances, Mössbauer effect) Impact factor: 2.465, year: 2016

  11. Network Coding for Wireless Cooperative Networks

    DEFF Research Database (Denmark)

    Khamfroush, Hana; Roetter, Daniel Enrique Lucani; Barros, João

    2014-01-01

    We consider the problem of finding an optimal packet transmission policy that minimizes the total cost of transmitting M data packets from a source S to two receivers R1,R2 over half-duplex, erasure channels. The source can either broadcast random linear network coding (RLNC) packets to the recei......We consider the problem of finding an optimal packet transmission policy that minimizes the total cost of transmitting M data packets from a source S to two receivers R1,R2 over half-duplex, erasure channels. The source can either broadcast random linear network coding (RLNC) packets...... to the receivers or transmit using unicast sessions at each time slot. We assume that the receivers can share their knowledge with each other by sending RLNC packets using unicast transmissions. We model this problem by using a Markov Decision Process (MDP), where the actions include the source of and type...... of transmission to be used in a given time slot given perfect knowledge of the system state. We study the distribution of actions selected by the MDP in terms of the knowledge at the receivers, the channel erasure probabilities, and the ratio between the cost of broadcast and unicast. This allowed us to learn...

  12. Packet Capture Solutions: PcapDB Benchmark for High-Bandwidth Capture, Storage, and Searching

    Energy Technology Data Exchange (ETDEWEB)

    Steinfadt, Shannon Irene [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Ferrell, Paul Steven [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-03-21

    PcapDB stands alone when looking at the overall field of competitors, from the cost-effective COTS hardware, to the efficient utilization of disk space that enables a longer packet history. A scalable, 100GbE-enabled system that indexes every packet and indexes flow data without complicated load-balancing requirements. The Transport Layer search and indexing approach led to patent-pending flow indexing technology, providing a specialized database system specifically optimized around providing fast flow searches. While there are a plethora of options in network packet capture, there are very few that are able to effectively manage capture rates of more than 10 Gb/s, distributed capture and querying, and a responsive user interface. By far, the primary competitor in the market place is Endace and DeepSee; in addition to meeting the technical requirements we set out in this document, they provide technical support and a fully 'appliance like' system. In terms of cost, however, our experience has been that the yearly maintenance charges alone outstrip the entire hardware cost of solutions like PcapDB. Investment in cyber security research and development is a large part of what has enabled us to build the base of knowlegable workers needed to defend government resources in the rapidly evolving cyber security landscape. We believe projects like Bro, WireCap, and Farm do more than just fill temporary gaps in our capabilities. They give allow us to build the firm foundation needed to tackle the next generation of cyber challenges. PcapDB was built with loftier ambitions than simply solving the packet capture of a single lab site, but instead to provide a robust, scaleable packet capture solution to the DOE complex and beyond.

  13. Estimation of network path segment delays

    Science.gov (United States)

    Nichols, Kathleen Marie

    2018-05-01

    A method for estimation of a network path segment delay includes determining a scaled time stamp for each packet of a plurality of packets by scaling a time stamp for each respective packet to minimize a difference of at least one of a frequency and a frequency drift between a transport protocol clock of a host and a monitoring point. The time stamp for each packet is provided by the transport protocol clock of the host. A corrected time stamp for each packet is determined by removing from the scaled time stamp for each respective packet, a temporal offset between the transport protocol clock and the monitoring clock by minimizing a temporal delay variation of the plurality of packets traversing a segment between the host and the monitoring point.

  14. A study of artificial speech quality assessors of VoIP calls subject to limited bursty packet losses

    Directory of Open Access Journals (Sweden)

    Jelassi Sofiene

    2011-01-01

    Full Text Available Abstract A revolutionary feature of emerging media services over the Internet is their ability to account for human perception during service delivery processes, which surely increases their popularity and incomes. In such a situation, it is necessary to understand the users' perception, what should obviously be done using standardized subjective experiences. However, it is also important to develop artificial quality assessors that enable to automatically quantify the perceived quality. This efficiently helps performing optimal network and service management at the core and edges of the delivery systems. In our article, we explore the behavior rating of new emerging artificial speech quality assessors of VoIP calls subject to moderately bursty packet loss processes. The examined Speech Quality Assessment (SQA algorithms are able to estimate speech quality of live VoIP calls at run-time using control information extracted from header content of received packets. They are especially designed to be sensitive to packet loss burstiness. The performance evaluation study is performed using a dedicated set-up software-based SQA framework. It offers a specialized packet killer and includes the implementation of four SQA algorithms. A speech quality database, which covers a wide range of bursty packet loss conditions, has been created and then thoroughly analyzed. Our main findings are the following: (1 all examined automatic bursty-loss aware speech quality assessors achieve a satisfactory correlation under upper (> 20% and lower (< 10% ranges of packet loss processes; (2 they exhibit a clear weakness to assess speech quality under a moderated packet loss process; (3 the accuracy of sequence-by-sequence basis of examined SQA algorithms should be addressed in detail for further precision.

  15. Collective neutrino oscillations and neutrino wave packets

    Energy Technology Data Exchange (ETDEWEB)

    Akhmedov, Evgeny; Lindner, Manfred [Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, 69117 Heidelberg (Germany); Kopp, Joachim, E-mail: akhmedov@mpi-hd.mpg.de, E-mail: jkopp@uni-mainz.de, E-mail: lindner@mpi-hd.mpg.de [PRISMA Cluster of Excellence and Mainz Institute for Theoretical Physics, Johannes Gutenberg University, 55099 Mainz (Germany)

    2017-09-01

    Effects of decoherence by wave packet separation on collective neutrino oscillations in dense neutrino gases are considered. We estimate the length of the wave packets of neutrinos produced in core collapse supernovae and the expected neutrino coherence length, and then proceed to consider the decoherence effects within the density matrix formalism of neutrino flavour transitions. First, we demonstrate that for neutrino oscillations in vacuum the decoherence effects are described by a damping term in the equation of motion of the density matrix of a neutrino as a whole (as contrasted to that of the fixed-momentum components of the neutrino density matrix). Next, we consider neutrino oscillations in ordinary matter and dense neutrino backgrounds, both in the adiabatic and non-adiabatic regimes. In the latter case we study two specific models of adiabaticity violation—one with short-term and another with extended non-adiabaticity. It is demonstrated that, while in the adiabatic case a damping term is present in the equation of motion of the neutrino density matrix (just like in the vacuum oscillation case), no such term in general appears in the non-adiabatic regime.

  16. Scattering of wave packets with phases

    Energy Technology Data Exchange (ETDEWEB)

    Karlovets, Dmitry V. [Department of Physics, Tomsk State University, Lenina Ave. 36, 634050 Tomsk (Russian Federation)

    2017-03-09

    A general problem of 2→N{sub f} scattering is addressed with all the states being wave packets with arbitrary phases. Depending on these phases, one deals with coherent states in (3+1) D, vortex particles with orbital angular momentum, the Airy beams, and their generalizations. A method is developed in which a number of events represents a functional of the Wigner functions of such states. Using width of a packet σ{sub p}/〈p〉 as a small parameter, the Wigner functions, the number of events, and a cross section are represented as power series in this parameter, the first non-vanishing corrections to their plane-wave expressions are derived, and generalizations for beams are made. Although in this regime the Wigner functions turn out to be everywhere positive, the cross section develops new specifically quantum features, inaccessible in the plane-wave approximation. Among them is dependence on an impact parameter between the beams, on phases of the incoming states, and on a phase of the scattering amplitude. A model-independent analysis of these effects is made. Two ways of measuring how a Coulomb phase and a hadronic one change with a transferred momentum t are discussed.

  17. Congestion control in wireless links based on selective delivery of erroneous packets

    DEFF Research Database (Denmark)

    Korhonen, Jari; Perkis, Andrew; Reiter, Ulrich

    2011-01-01

    Traditionally, congestion control in packet networks is performed by reducing the transmission rate when congestion is detected, in order to cut down the traffic that overwhelms the capacity of the network. However, if the bottleneck is a wireless link, congestion is often cumulated because...... the performance of the proposed mechanism against traditional congestion control with a simulation study. The results show that the proposed approach can improve the overall performance both by increasing the throughput over the wireless and improving the video quality in terms of peak signal-to-noise ratio (PSNR...

  18. 41 CFR 101-39.306 - Operator's packet.

    Science.gov (United States)

    2010-07-01

    ...-INTERAGENCY FLEET MANAGEMENT SYSTEMS 39.3-Use and Care of GSA Interagency Fleet Management System Vehicles § 101-39.306 Operator's packet. The GSA Interagency Fleet Management System (IFMS) will provide each... 41 Public Contracts and Property Management 2 2010-07-01 2010-07-01 true Operator's packet. 101-39...

  19. Wave packet construction in three-dimensional quantum billiards

    Indian Academy of Sciences (India)

    We examine the dynamical evolution of wave packets in a cubical billiard where three quantum numbers (, , ) determine its energy spectrum and consequently its dynamical behaviour. We have constructed the wave packet in the cubical billiard and have observed its time evolution for various closed orbits.

  20. Label-controlled optical packet routing technologies and applications

    DEFF Research Database (Denmark)

    Koonen, A.M.J.; Yan, N.; Vegas Olmos, Juan José

    2007-01-01

    An overview is given of various optical packet labeling techniques. The architecture and technologies are discussed for optical packet routing nodes using orthogonal labeling with optoelectronic label processing, and for nodes using time-serial labeling with all-optical time-serial label processing...

  1. MODELLING AND VERIFICATION OF KITSAT PACKET COMMUNICATION PROTOCOLS

    Directory of Open Access Journals (Sweden)

    Young-Ro Lee

    1996-06-01

    Full Text Available In this paper, in order to verify KITSAT 1/2 packet communication protocols, we model the AX.25 protocol and PACSAT protocol by using an extended Petri net and then verify the correctness, boundedness, liveness and deadlock freeness of packet protocols by utilizing reachability trees.

  2. Do Free Quantum-Mechanical Wave Packets Always Spread?

    Science.gov (United States)

    Klein, James R.

    1980-01-01

    The spreading or shrinking of free three-dimensional quantum-mechanical wave packets is addressed. A seeming paradox concerning the time evolution operator and nonspreading wave packets is discussed, and the necessity of taking into account the appropriate mathematical structure of quantum mechanics is emphasized. Teaching implications are given.…

  3. Controlling the spreading of wave packets of a dissociating molecule

    DEFF Research Database (Denmark)

    Tiwari, Ashwani Kumar; Møller, Klaus Braagaard; Henriksen, Niels Engholm

    2007-01-01

    A first-order perturbation theoretic approach within the electric-dipole approximation is used to study the time evolution of wave packets created by linearly chirped laser pulses on a repulsive potential of Br-2. Our calculations show that negatively chirped pulses focus the wave packet in the F...

  4. Dance Theatre of Harlem--Theater Activity Packet.

    Science.gov (United States)

    New York City Board of Education, Brooklyn, NY. Div. of Curriculum and Instruction.

    Intended to complement the New York City communication arts curriculum, this packet introduces young students, guided by the classroom teacher, to a dress rehearsal performance of the Dance Theatre of Harlem ballet company. The packet is one of a series in the "Early Stages" program, a joint effort of the Mayor's Office of Film, Theater…

  5. Langston Hughes Curriculum Packet: Dig and Be Dug in Return.

    Science.gov (United States)

    Danielson, Susan

    Designed in a flexible format for use by college instructors, high school teachers, and community education workers, this curriculum packet serves as an introduction to the life and works of black poet Langston Hughes. The major component of the packet is a critical essay that explores the thematic highlights of Hughes's career. The remaining…

  6. Electron Rydberg wave packets in one-dimensional atoms

    Indian Academy of Sciences (India)

    produced by the application of a single impulsive kick was explicitly demonstrated. The undulation of ..... In this context, let us divide the wave packet .... wave packet with special attention to the time evolution of its components associ- ated with ...

  7. SDRAM-based packet buffer model for high speed switches

    DEFF Research Database (Denmark)

    Rasmussen, Anders; Ruepp, Sarah Renée; Berger, Michael Stübert

    2011-01-01

    based on the specifications of a real-life DDR3-SDRAM chip. Based on this model the performance of different schemes for optimizing the performance of such a packet buffer can be evaluated. The purpose of this study is to find efficient schemes for memory mapping of the packet queues and I/O traffic...

  8. Manifestations of wave packet revivals in the moments of observables

    International Nuclear Information System (INIS)

    Sudheesh, C.; Lakshmibala, S.; Balakrishnan, V.

    2004-01-01

    Using a generic Hamiltonian that models wave packet propagation in a Kerr-like medium, matter wave field dynamics in Bose-Einstein condensation, etc., we show that distinctive signatures of wave packet revivals and fractional revivals are displayed by the time evolution of the expectation values of appropriate observables, enabling selective identification of different fractional revivals

  9. Systematic Sampling and Cluster Sampling of Packet Delays

    OpenAIRE

    Lindh, Thomas

    2006-01-01

    Based on experiences of a traffic flow performance meter this papersuggests and evaluates cluster sampling and systematic sampling as methods toestimate average packet delays. Systematic sampling facilitates for exampletime analysis, frequency analysis and jitter measurements. Cluster samplingwith repeated trains of periodically spaced sampling units separated by randomstarting periods, and systematic sampling are evaluated with respect to accuracyand precision. Packet delay traces have been ...

  10. All-optical devices for ultrafast packet switching

    DEFF Research Database (Denmark)

    Dorren, H.J.S.; HerreraDorren, J.; Raz, O.

    2007-01-01

    We discuss integrated devices for all-optical packet switching. We focus on monolithically integrated all-optical flip-flops, ultra-fast semiconductor based wavelength converters and explain the operation principles. Finally, a 160 Gb/s all-optical packet switching experiment over 110 km of field...

  11. Exact wave packet decoherence dynamics in a discrete spectrum environment

    International Nuclear Information System (INIS)

    Tu, Matisse W Y; Zhang Weimin

    2008-01-01

    We find an exact analytical solution of the reduced density matrix from the Feynman-Vernon influence functional theory for a wave packet in an environment containing a few discrete modes. We obtain two intrinsic energy scales relating to the time scales of the system and the environment. The different relationship between these two scales alters the overall form of the solution of the system. We also introduce a decoherence measure for a single wave packet which is defined as the ratio of Schroedinger uncertainty over the delocalization extension of the wave packet and characterizes the time-evolution behaviour of the off-diagonal reduced density matrix element. We utilize the exact solution and the decoherence measure to study the wave packet decoherence dynamics. We further demonstrate how the dynamical diffusion of the wave packet leads to non-Markovian decoherence in such a microscopic environment.

  12. Active Traffic Capture for Network Forensics

    Science.gov (United States)

    Slaviero, Marco; Granova, Anna; Olivier, Martin

    Network traffic capture is an integral part of network forensics, but current traffic capture techniques are typically passive in nature. Under heavy loads, it is possible for a sniffer to miss packets, which affects the quality of forensic evidence.

  13. A Method for Routing Packets Across Multiple Paths in NoCs with In-Order Delivery and Fault-Tolerance Gaurantees

    Directory of Open Access Journals (Sweden)

    Srinivasan Murali

    2007-01-01

    Full Text Available Networks on Chips (NoCs are required to tackle the increasing delay and poor scalability issues of bus-based communication architectures. Many of today's NoC designs are based on single path routing. By utilizing multiple paths for routing, congestion in the network is reduced significantly, which translates to improved network performance or reduced network bandwidth requirements and power consumption. Multiple paths can also be utilized to achieve spatial redundancy, which helps in achieving tolerance against faults or errors in the NoC. A major problem with multipath routing is that packets can reach the destination in an out-of-order fashion, while many applications require in-order packet delivery. In this work, we present a multipath routing strategy that guarantees in-order packet delivery for NoCs. It is based on the idea of routing packets on partially nonintersecting paths and rebuilding packet order at path reconvergent nodes. We present a design methodology that uses the routing strategy to optimally spread the traffic in the NoC to minimize the network bandwidth needs and power consumption. We also integrate support for tolerance against transient and permanent failures in the NoC links in the methodology by utilizing spatial and temporal redundancy for transporting packets. Our experimental studies show large reduction in network bandwidth requirements (36.86% on average and power consumption (30.51% on average compared to single-path systems. The area overhead of the proposed scheme is small (a modest 5% increase in network area. Hence, it is practical to be used in the on-chip domain.

  14. Three-dimensional electromagnetic strong turbulence. II. Wave packet collapse and structure of wave packets during strong turbulence

    International Nuclear Information System (INIS)

    Graham, D. B.; Robinson, P. A.; Cairns, Iver H.; Skjaeraasen, O.

    2011-01-01

    Large-scale simulations of wave packet collapse are performed by numerically solving the three-dimensional (3D) electromagnetic Zakharov equations, focusing on individual wave packet collapses and on wave packets that form in continuously driven strong turbulence. The collapse threshold is shown to decrease as the electron thermal speed ν e /c increases and as the temperature ratio T i /T e of ions to electrons decreases. Energy lost during wave packet collapse and dissipation is shown to depend on ν e /c. The dynamics of density perturbations after collapse are studied in 3D electromagnetic strong turbulence for a range of T i /T e . The structures of the Langmuir, transverse, and total electric field components of wave packets during strong turbulence are investigated over a range of ν e /c. For ν e /c e /c > or approx. 0.17, transverse modes become trapped in density wells and contribute significantly to the structure of the total electric field. At all ν e /c, the Langmuir energy density contours of wave packets are predominantly oblate (pancake shaped). The transverse energy density contours of wave packets are predominantly prolate (sausage shaped), with the major axis being perpendicular to the major axes of the Langmuir component. This results in the wave packet becoming more nearly spherical as ν e /c increases, and in turn generates more spherical density wells during collapse. The results obtained are compared with previous 3D electrostatic results and 2D electromagnetic results.

  15. Waveform and packet structure of lion roars

    Directory of Open Access Journals (Sweden)

    W. Baumjohann

    Full Text Available The Equator-S magnetometer is very sensitive and has a sampling rate of normally 128 Hz. The high sampling rate allows for the first time fluxgate magnetometer measurements of ELF waves between the ion cyclotron and the lower hybrid frequencies in the equatorial dayside magnetosheath. The so-called lion roars, typically seen by the Equator-S magnetometer at the bottom of the magnetic troughs of magnetosheath mirror waves, are near-monochromatic packets of electron whistler waves lasting for a few wave cycles only, typically 0.25 s. They are right-hand circularly polarized waves with typical amplitudes of 0.5–1 nT at around one tenth of the electron gyrofrequency. The cone angle between wave vector and ambient field is usually smaller than 1.5°.

    Key words. Interplanetary physics (MHD waves and turbulence; plasma waves and turbulence

  16. Waveform and packet structure of lion roars

    Directory of Open Access Journals (Sweden)

    W. Baumjohann

    1999-12-01

    Full Text Available The Equator-S magnetometer is very sensitive and has a sampling rate of normally 128 Hz. The high sampling rate allows for the first time fluxgate magnetometer measurements of ELF waves between the ion cyclotron and the lower hybrid frequencies in the equatorial dayside magnetosheath. The so-called lion roars, typically seen by the Equator-S magnetometer at the bottom of the magnetic troughs of magnetosheath mirror waves, are near-monochromatic packets of electron whistler waves lasting for a few wave cycles only, typically 0.25 s. They are right-hand circularly polarized waves with typical amplitudes of 0.5–1 nT at around one tenth of the electron gyrofrequency. The cone angle between wave vector and ambient field is usually smaller than 1.5°.Key words. Interplanetary physics (MHD waves and turbulence; plasma waves and turbulence

  17. Wave packets, Maslov indices, and semiclassical quantization

    International Nuclear Information System (INIS)

    Littlejohn, R.G.

    1989-01-01

    The Bohr-Sommerfeld quantization condition, as refined by Keller and Maslov, reads I=(n+m/4)h, where I is the classical action, n is the quantum number, and where m is the Maslov index, an even integer. The occurrence of the integers n and m in this formula is a reflection of underlying topological features of semiclassical quantization. In particular, the work of Arnold and others has shown that m/2 is a winding number of closed curves on the classical symplectic group manifold, Sp(2N). Wave packets provide a simple and elegant means of establishing the connection between semiclassical quantization and the homotopy classes of Sp(2N), as well as a practical way of calculating Maslov indices in complex problems. Topological methods can also be used to derive general formulas for the Maslov indices of invariant tori in the classical phase space corresponding to resonant motion. (orig.)

  18. Construction of localized atomic wave packets

    International Nuclear Information System (INIS)

    Ranjani, S Sree; Kapoor, A K; Panigrahi, P K

    2010-01-01

    It is shown that highly localized solitons can be created in lower dimensional Bose-Einstein condensates (BECs), trapped in a regular harmonic trap, by temporally varying the trap frequency. A BEC confined in such a trap can be effectively used to construct a pulsed atomic laser emitting coherent atomic wave packets. In addition to having a complete control over the spatio-temporal dynamics of the solitons, we can separate the equation governing the Kohn mode (centre of mass motion). We investigate the effect of the temporal modulation of the trap frequency on the spatio-temporal dynamics of the bright solitons and also on the Kohn mode. The dynamics of the solitons and the variations in the Kohn mode with time are compared with those in a BEC confined in a trap with unmodulated trap frequency.

  19. Ad hoc networking scheme for mobile cyber-physical systems

    KAUST Repository

    Bader, Ahmed

    2017-08-17

    Embodiments of the present disclosure provide techniques for packet routing. In an embodiment, when a transmitting communication device injects a packet into a communication network, a receiving communication device that is closer to a sink or destination than the transmitting communication device relays the packet in a first hop. In a subsequent hop, a receiving communication device evaluates position information conveyed by the transmitting communication device of the first hop to determine whether to forward the packet. Accordingly, a receiving communication device receiver that offers progress towards the sink can elect to forward the packet.

  20. Mixture block coding with progressive transmission in packet video. Appendix 1: Item 2. M.S. Thesis

    Science.gov (United States)

    Chen, Yun-Chung

    1989-01-01

    Video transmission will become an important part of future multimedia communication because of dramatically increasing user demand for video, and rapid evolution of coding algorithm and VLSI technology. Video transmission will be part of the broadband-integrated services digital network (B-ISDN). Asynchronous transfer mode (ATM) is a viable candidate for implementation of B-ISDN due to its inherent flexibility, service independency, and high performance. According to the characteristics of ATM, the information has to be coded into discrete cells which travel independently in the packet switching network. A practical realization of an ATM video codec called Mixture Block Coding with Progressive Transmission (MBCPT) is presented. This variable bit rate coding algorithm shows how a constant quality performance can be obtained according to user demand. Interactions between codec and network are emphasized including packetization, service synchronization, flow control, and error recovery. Finally, some simulation results based on MBCPT coding with error recovery are presented.

  1. Improving Packet Processing Performance in the ATLAS FELIX Project

    CERN Document Server

    AUTHOR|(SzGeCERN)752705; The ATLAS collaboration; Anderson, John Thomas; Borga, Andrea; Boterenbrood, Hendrik; Chen, Hucheng; Chen, Kai; Drake, Gary; Francis, David; Gorini, Benedetto; Lanni, Francesco; Lehmann Miotto, Giovanna; Levinson, Lorne; Narevicius, Julia; Plessl, Christian; Roich, Alexander; Ryu, Soo; Schreuder, Frans Philip; Vandelli, Wainer; Zhang, Jinlong; Vermeulen, Jos

    2015-01-01

    Experiments in high-energy physics (HEP) and related fields often impose constraints and challenges on data acquisition systems. As a result, these systems are implemented as unique mixtures of custom and commercial-off-the-shelf electronics (COTS), involving and connecting radiation-hard devices, large high-performance networks, and computing farms. FELIX, the Frontend Link Exchange, is a new PC-based general purpose data routing device for the data-acquisition system of the ATLAS experiment at CERN. Performance is a very crucial point for devices like FELIX, which have to be capable of processing tens of gigabyte of data per second. Thus it is important to understand the performance limitations for typical workloads on modern hardware. We present an analysis of a packet processing algorithm that is used in FELIX, and show how the PC system's memory architecture plays a key factor in the overall data throughput achieved by the application. Finally, we present optimizations that increase the processing throug...

  2. Wavelet Packet Transform Based Driver Distraction Level Classification Using EEG

    Directory of Open Access Journals (Sweden)

    Mousa Kadhim Wali

    2013-01-01

    Full Text Available We classify the driver distraction level (neutral, low, medium, and high based on different wavelets and classifiers using wireless electroencephalogram (EEG signals. 50 subjects were used for data collection using 14 electrodes. We considered for this research 4 distraction stimuli such as Global Position Systems (GPS, music player, short message service (SMS, and mental tasks. Deriving the amplitude spectrum of three different frequency bands theta, alpha, and beta of EEG signals was based on fusion of discrete wavelet packet transform (DWPT and FFT. Comparing the results of three different classifiers (subtractive fuzzy clustering probabilistic neural network, -nearest neighbor was based on spectral centroid, and power spectral features extracted by different wavelets (db4, db8, sym8, and coif5. The results of this study indicate that the best average accuracy achieved by subtractive fuzzy inference system classifier is 79.21% based on power spectral density feature extracted by sym8 wavelet which gave a good class discrimination under ANOVA test.

  3. Collaborative Multi-Layer Network Coding in Hybrid Cellular Cognitive Radio Networks

    KAUST Repository

    Moubayed, Abdallah J.; Sorour, Sameh; Al-Naffouri, Tareq Y.; Alouini, Mohamed-Slim

    2015-01-01

    In this paper, as an extension to [1], we propose a prioritized multi-layer network coding scheme for collaborative packet recovery in hybrid (interweave and underlay) cellular cognitive radio networks. This scheme allows the uncoordinated

  4. Collaborative Multi-Layer Network Coding For Hybrid Cellular Cognitive Radio Networks

    KAUST Repository

    Moubayed, Abdallah J.

    2014-01-01

    In this thesis, as an extension to [1], we propose a prioritized multi-layer network coding scheme for collaborative packet recovery in hybrid (interweave and underlay) cellular cognitive radio networks. This scheme allows the uncoordinated

  5. Detection Performance of Packet Arrival under Downclocking for Mobile Edge Computing

    Directory of Open Access Journals (Sweden)

    Zhimin Wang

    2018-01-01

    Full Text Available Mobile edge computing (MEC enables battery-powered mobile nodes to acquire information technology services at the network edge. These nodes desire to enjoy their service under power saving. The sampling rate invariant detection (SRID is the first downclocking WiFi technique that can achieve this objective. With SRID, a node detects one packet arrival at a downclocked rate. Upon a successful detection, the node reverts to a full-clocked rate to receive the packet immediately. To ensure that a node acquires its service immediately, the detection performance (namely, the miss-detection probability and the false-alarm probability of SRID is of importance. This paper is the first one to theoretically study the crucial impact of SRID attributes (e.g., tolerance threshold, correlation threshold, and energy ratio threshold on the packet detection performance. Extensive Monte Carlo experiments show that our theoretical model is very accurate. This study can help system developers set reasonable system parameters for WiFi downclocking.

  6. On Stochastic Finite-Time Control of Discrete-Time Fuzzy Systems with Packet Dropout

    Directory of Open Access Journals (Sweden)

    Yingqi Zhang

    2012-01-01

    Full Text Available This paper is concerned with the stochastic finite-time stability and stochastic finite-time boundedness problems for one family of fuzzy discrete-time systems over networks with packet dropout, parametric uncertainties, and time-varying norm-bounded disturbance. Firstly, we present the dynamic model description studied, in which the discrete-time fuzzy T-S systems with packet loss can be described by one class of fuzzy Markovian jump systems. Then, the concepts of stochastic finite-time stability and stochastic finite-time boundedness and problem formulation are given. Based on Lyapunov function approach, sufficient conditions on stochastic finite-time stability and stochastic finite-time boundedness are established for the resulting closed-loop fuzzy discrete-time system with Markovian jumps, and state-feedback controllers are designed to ensure stochastic finite-time stability and stochastic finite-time boundedness of the class of fuzzy systems. The stochastic finite-time stability and stochastic finite-time boundedness criteria can be tackled in the form of linear matrix inequalities with a fixed parameter. As an auxiliary result, we also give sufficient conditions on the stochastic stability of the class of fuzzy T-S systems with packet loss. Finally, two illustrative examples are presented to show the validity of the developed methodology.

  7. Coulomb Final State Interactions for Gaussian Wave Packets

    CERN Document Server

    Wiedemann, Urs Achim; Heinz, Ulrich W

    1999-01-01

    Two-particle like-sign and unlike-sign correlations including Coulomb final state interactions are calculated for Gaussian wave packets emitted from a Gaussian source. We show that the width of the wave packets can be fully absorbed into the spatial and momentum space widths of an effective emission function for plane wave states, and that Coulomb final state interaction effects are sensitive only to the latter, but not to the wave packet width itself. Results from analytical and numerical calculations are compared with recently published work by other authors.

  8. Observation of moving wave packets reveals their quantum state

    International Nuclear Information System (INIS)

    Leonhardt, U.; Raymer, M.G.

    1996-01-01

    We show how to infer the quantum state of a wave packet from position probability distributions measured during the packet close-quote s motion in an arbitrary potential. We assume a nonrelativistic one-dimensional or radial wave packet. Temporal Fourier transformation and spatial sampling with respect to a newly found set of functions project the density-matrix elements out of the probability distributions. The sampling functions are derivatives of products of regular and irregular wave functions. We note that the ability to infer quantum states in this way depends on the structure of the Schroedinger equation. copyright 1996 The American Physical Society

  9. Packetizing OCP Transactions in the MANGO Network-on-Chip

    DEFF Research Database (Denmark)

    Bjerregaard, Tobias; Sparsø, Jens

    2006-01-01

    facilitating IP reuse by standard socket access points. Two types of services are available: connection-less best-effort routing and connection-oriented guaranteed service (GS) routing. This paper presents the core-centric programming model for establishing and using GS connections in MANGO. We show how OCP...

  10. Path Diversity Media Streaming over Best Effort Packet Switched Networks

    Science.gov (United States)

    2003-01-01

    intolerable sounds of my violin practice, but my mom was always there to defend and encourage her young violinist. When I left my full-time job for graduate...information can be incomplete or inaccurate. For exam - ple, traceroute can only differentiate between routers and not switches. Two paths with completely

  11. Information transmission on hybrid networks

    Science.gov (United States)

    Chen, Rongbin; Cui, Wei; Pu, Cunlai; Li, Jie; Ji, Bo; Gakis, Konstantinos; Pardalos, Panos M.

    2018-01-01

    Many real-world communication networks often have hybrid nature with both fixed nodes and moving modes, such as the mobile phone networks mainly composed of fixed base stations and mobile phones. In this paper, we discuss the information transmission process on the hybrid networks with both fixed and mobile nodes. The fixed nodes (base stations) are connected as a spatial lattice on the plane forming the information-carrying backbone, while the mobile nodes (users), which are the sources and destinations of information packets, connect to their current nearest fixed nodes respectively to deliver and receive information packets. We observe the phase transition of traffic load in the hybrid network when the packet generation rate goes from below and then above a critical value, which measures the network capacity of packets delivery. We obtain the optimal speed of moving nodes leading to the maximum network capacity. We further improve the network capacity by rewiring the fixed nodes and by considering the current load of fixed nodes during packets transmission. Our purpose is to optimize the network capacity of hybrid networks from the perspective of network science, and provide some insights for the construction of future communication infrastructures.

  12. Efficient incremental relaying for packet transmission over fading channels

    KAUST Repository

    Fareed, Muhammad Mehboob; Alouini, Mohamed-Slim; Yang, Hongchuan

    2014-01-01

    In this paper, we propose a novel relaying scheme for packet transmission over fading channels, which improves the spectral efficiency of cooperative diversity systems by utilizing limited feedback from the destination. Our scheme capitalizes

  13. Further Results on Extended Delivery Time for Secondary Packet Transmission

    KAUST Repository

    Usman, Muneer; Yang, Hong-Chuan; Alouini, Mohamed-Slim

    2017-01-01

    with non-work-preserving strategy, where interrupted packets must be repeated. We also analyze the effect of imperfect periodic sensing, i.e., the secondary user periodically senses the spectrum for availability, with a chance of missing an available

  14. Massachusetts Bay - Internal wave packets digitized from SAR imagery

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This feature class contains internal wave packets digitized from SAR imagery at 1:350,000 scale in Massachusetts Bay. Internal waves are nonsinusoidal waves that...

  15. Transfer of a wave packet in double-well potential

    Science.gov (United States)

    Yang, Hai-Feng; Hu, Yao-Hua; Tan, Yong-Gang

    2018-04-01

    Energy potentials with double-well structures are typical in atoms and molecules systems. A manipulation scheme using Half Cycles Pulses (HCPs) is proposed to transfer a Gaussian wave packet between the two wells. On the basis of quantum mechanical simulations, the time evolution and the energy distribution of the wave packet are evaluated. The effect of time parameters, amplitude, and number of HCPs on spatial and energy distribution of the final state and transfer efficiency are investigated. After a carefully tailored HCPs sequence is applied to the initial wave packet localized in one well, the final state is a wave packet localized in the other well and populated at the lower energy levels with narrower distribution. The present scheme could be used to control molecular reactions and to prepare atoms with large dipole moments.

  16. Further Results on Extended Delivery Time for Secondary Packet Transmission

    KAUST Repository

    Usman, Muneer

    2017-07-10

    Cognitive radio transceiver can opportunistically access the underutilized spectrum resource of primary systems for new wireless services. With interweave cognitive implementation, secondary transmission may be interrupted by primary transmission. To facilitate the packet delay analysis of such secondary transmission, we study the extended delivery time of secondary packet transmission. In particular, we derive the exact distribution function of extended delivery time of a fixed-size secondary packet with non-work-preserving strategy, where interrupted packets must be repeated. We also analyze the effect of imperfect periodic sensing, i.e., the secondary user periodically senses the spectrum for availability, with a chance of missing an available channel on a certain sensing attempt. These results complement previous work on work-preserving strategy with perfect sensing. Selected numerical and simulation results are presented for verifying the mathematical formulation.

  17. Resonance-assisted decay of nondispersive wave packets

    OpenAIRE

    Wimberger, S.; Schlagheck, P.; Eltschka, C.; Buchleitner, A.

    2006-01-01

    We present a quantitative semiclassical theory for the decay of nondispersive electronic wave packets in driven, ionizing Rydberg systems. Statistically robust quantities are extracted combining resonance assisted tunneling with subsequent transport across chaotic phase space and a final ionization step.

  18. Engineering and manipulating exciton wave packets

    Science.gov (United States)

    Zang, Xiaoning; Montangero, Simone; Carr, Lincoln D.; Lusk, Mark T.

    2017-05-01

    When a semiconductor absorbs light, the resulting electron-hole superposition amounts to a uncontrolled quantum ripple that eventually degenerates into diffusion. If the conformation of these excitonic superpositions could be engineered, though, they would constitute a new means of transporting information and energy. We show that properly designed laser pulses can be used to create such excitonic wave packets. They can be formed with a prescribed speed, direction, and spectral make-up that allows them to be selectively passed, rejected, or even dissociated using superlattices. Their coherence also provides a handle for manipulation using active, external controls. Energy and information can be conveniently processed and subsequently removed at a distant site by reversing the original procedure to produce a stimulated emission. The ability to create, manage, and remove structured excitons comprises the foundation for optoexcitonic circuits with application to a wide range of quantum information, energy, and light-flow technologies. The paradigm is demonstrated using both tight-binding and time-domain density functional theory simulations.

  19. Design issues of a back-pressure-based congestion control mechanism

    NARCIS (Netherlands)

    Malhotra, R.; Mandjes, M.R.H.; Scheinhardt, W.R.W.; Berg, van den J.L.

    2008-01-01

    Congestion control in packet-based networks is often realized by feedback protocols -- in this paper we assess the performance under a back-pressure mechanism that has been proposed and standardized for Ethernet metropolitan networks. Relying on our earlier results for feedback fluid queues, we

  20. On the Impact of Zero-padding in Network Coding Efficiency with Internet Traffic and Video Traces

    DEFF Research Database (Denmark)

    Taghouti, Maroua; Roetter, Daniel Enrique Lucani; Pedersen, Morten Videbæk

    2016-01-01

    Random Linear Network Coding (RLNC) theoretical results typically assume that packets have equal sizes while in reality, data traffic presents a random packet size distribution. Conventional wisdom considers zero-padding of original packets as a viable alternative, but its effect can reduce the e...

  1. Zone routing in a torus network

    Science.gov (United States)

    Chen, Dong; Heidelberger, Philip; Kumar, Sameer

    2013-01-29

    A system for routing data in a network comprising a network logic device at a sending node for determining a path between the sending node and a receiving node, wherein the network logic device sets one or more selection bits and one or more hint bits within the data packet, a control register for storing one or more masks, wherein the network logic device uses the one or more selection bits to select a mask from the control register and the network logic device applies the selected mask to the hint bits to restrict routing of the data packet to one or more routing directions for the data packet within the network and selects one of the restricted routing directions from the one or more routing directions and sends the data packet along a link in the selected routing direction toward the receiving node.

  2. On wave-packet dynamics in a decaying quadratic potential

    DEFF Research Database (Denmark)

    Møller, Klaus Braagaard; Henriksen, Niels Engholm

    1997-01-01

    We consider the time-dependent Schrodinger equation for a quadratic potential with an exponentially decaying force constant. General analytical solutions are presented and we highlight in particular, the signatures of classical mechanics in the wave packet dynamics.......We consider the time-dependent Schrodinger equation for a quadratic potential with an exponentially decaying force constant. General analytical solutions are presented and we highlight in particular, the signatures of classical mechanics in the wave packet dynamics....

  3. Jitter reduction in Differentiated Services (Diffserv) networks

    NARCIS (Netherlands)

    Karagiannis, Georgios; Rexhepi, Vlora

    2001-01-01

    A method and a computer program for reducing jitter in IP packet transmission in a Diffserv network having ingress and egress Border Routers and using premium service, expedited forwarding and source route option, recognize incoming packets which have firm jitter requirements. The program verifies

  4. Jitter reduction in Differentiated Services (Diffserv) networks

    NARCIS (Netherlands)

    Karagiannis, Georgios; Rexhepi, Vlora

    2005-01-01

    A method and a computer program for reducing jitter in IP packet transmission in a Diffserv network having ingress and egress Border Routers and using premium service, expedited forwarding and source route option, recognize incoming packets which have firm jitter requirements. The program verifies

  5. Length-Bounded Hybrid CPU/GPU Pattern Matching Algorithm for Deep Packet Inspection

    Directory of Open Access Journals (Sweden)

    Yi-Shan Lin

    2017-01-01

    Full Text Available Since frequent communication between applications takes place in high speed networks, deep packet inspection (DPI plays an important role in the network application awareness. The signature-based network intrusion detection system (NIDS contains a DPI technique that examines the incoming packet payloads by employing a pattern matching algorithm that dominates the overall inspection performance. Existing studies focused on implementing efficient pattern matching algorithms by parallel programming on software platforms because of the advantages of lower cost and higher scalability. Either the central processing unit (CPU or the graphic processing unit (GPU were involved. Our studies focused on designing a pattern matching algorithm based on the cooperation between both CPU and GPU. In this paper, we present an enhanced design for our previous work, a length-bounded hybrid CPU/GPU pattern matching algorithm (LHPMA. In the preliminary experiment, the performance and comparison with the previous work are displayed, and the experimental results show that the LHPMA can achieve not only effective CPU/GPU cooperation but also higher throughput than the previous method.

  6. Software Defined Coded Networking

    DEFF Research Database (Denmark)

    Di Paola, Carla; Roetter, Daniel Enrique Lucani; Palazzo, Sergio

    2017-01-01

    the quality of each link and even across neighbouring links and using simulations to show that an additional reduction of packet transmission in the order of 40% is possible. Second, to advocate for the use of network coding (NC) jointly with software defined networking (SDN) providing an implementation...

  7. Robust node estimation and topology discovery for large-scale networks

    KAUST Repository

    Alouini, Mohamed-Slim

    2017-02-23

    Various examples are provided for node estimation and topology discovery for networks. In one example, a method includes receiving a packet having an identifier from a first node; adding the identifier to another transmission packet based on a comparison between the first identifier and existing identifiers associated with the other packet; adjusting a transmit probability based on the comparison; and transmitting the other packet based on a comparison between the transmit probability and a probability distribution. In another example, a system includes a network device that can adds an identifier received in a packet to a list including existing identifiers and adjust a transmit probability based on a comparison between the identifiers; and transmit another packet based on a comparison between the transmit probability and a probability distribution. In another example, a method includes determining a quantity of sensor devices based on a plurality of identifiers received in a packet.

  8. Robust node estimation and topology discovery for large-scale networks

    KAUST Repository

    Alouini, Mohamed-Slim; Douik, Ahmed S.; Aly, Salah A.; Al-Naffouri, Tareq Y.

    2017-01-01

    Various examples are provided for node estimation and topology discovery for networks. In one example, a method includes receiving a packet having an identifier from a first node; adding the identifier to another transmission packet based on a comparison between the first identifier and existing identifiers associated with the other packet; adjusting a transmit probability based on the comparison; and transmitting the other packet based on a comparison between the transmit probability and a probability distribution. In another example, a system includes a network device that can adds an identifier received in a packet to a list including existing identifiers and adjust a transmit probability based on a comparison between the identifiers; and transmit another packet based on a comparison between the transmit probability and a probability distribution. In another example, a method includes determining a quantity of sensor devices based on a plurality of identifiers received in a packet.

  9. Fulcrum Network Codes

    DEFF Research Database (Denmark)

    2015-01-01

    Fulcrum network codes, which are a network coding framework, achieve three objectives: (i) to reduce the overhead per coded packet to almost 1 bit per source packet; (ii) to operate the network using only low field size operations at intermediate nodes, dramatically reducing complexity...... in the network; and (iii) to deliver an end-to-end performance that is close to that of a high field size network coding system for high-end receivers while simultaneously catering to low-end ones that can only decode in a lower field size. Sources may encode using a high field size expansion to increase...... the number of dimensions seen by the network using a linear mapping. Receivers can tradeoff computational effort with network delay, decoding in the high field size, the low field size, or a combination thereof....

  10. Attosecond Electron Wave Packet Dynamics in Strong Laser Fields

    International Nuclear Information System (INIS)

    Johnsson, P.; Remetter, T.; Varju, K.; L'Huillier, A.; Lopez-Martens, R.; Valentin, C.; Balcou, Ph.; Kazamias, S.; Mauritsson, J.; Gaarde, M. B.; Schafer, K. J.; Mairesse, Y.; Wabnitz, H.; Salieres, P.

    2005-01-01

    We use a train of sub-200 attosecond extreme ultraviolet (XUV) pulses with energies just above the ionization threshold in argon to create a train of temporally localized electron wave packets. We study the energy transfer from a strong infrared (IR) laser field to the ionized electrons as a function of the delay between the XUV and IR fields. When the wave packets are born at the zero crossings of the IR field, a significant amount of energy (∼20 eV) is transferred from the field to the electrons. This results in dramatically enhanced above-threshold ionization in conditions where the IR field alone does not induce any significant ionization. Because both the energy and duration of the wave packets can be varied independently of the IR laser, they are valuable tools for studying and controlling strong-field processes

  11. Optimization and Assessment of Wavelet Packet Decompositions with Evolutionary Computation

    Directory of Open Access Journals (Sweden)

    Schell Thomas

    2003-01-01

    Full Text Available In image compression, the wavelet transformation is a state-of-the-art component. Recently, wavelet packet decomposition has received quite an interest. A popular approach for wavelet packet decomposition is the near-best-basis algorithm using nonadditive cost functions. In contrast to additive cost functions, the wavelet packet decomposition of the near-best-basis algorithm is only suboptimal. We apply methods from the field of evolutionary computation (EC to test the quality of the near-best-basis results. We observe a phenomenon: the results of the near-best-basis algorithm are inferior in terms of cost-function optimization but are superior in terms of rate/distortion performance compared to EC methods.

  12. Airy Wave Packets Accelerating in Space-Time

    Science.gov (United States)

    Kondakci, H. Esat; Abouraddy, Ayman F.

    2018-04-01

    Although diffractive spreading is an unavoidable feature of all wave phenomena, certain waveforms can attain propagation invariance. A lesser-explored strategy for achieving optical self-similar propagation exploits the modification of the spatiotemporal field structure when observed in reference frames moving at relativistic speeds. For such an observer, it is predicted that the associated Lorentz boost can bring to a halt the axial dynamics of a wave packet of an arbitrary profile. This phenomenon is particularly striking in the case of a self-accelerating beam—such as an Airy beam—whose peak normally undergoes a transverse displacement upon free propagation. Here we synthesize an acceleration-free Airy wave packet that travels in a straight line by deforming its spatiotemporal spectrum to reproduce the impact of a Lorentz boost. The roles of the axial spatial coordinate and time are swapped, leading to "time diffraction" manifested in self-acceleration observed in the propagating Airy wave-packet frame.

  13. Foreign Material in the Gastrointestinal Tract: Cocaine Packets

    Directory of Open Access Journals (Sweden)

    Nurten Turkel Kucukmetin

    2014-01-01

    Full Text Available Smuggling drugs by swallowing or inserting into a body cavity is not only a serious and growing international crime, but can also lead to lethal medical complications. The most common cause of death in ‘body packers', people transporting drugs by ingesting a packet into the gastrointestinal tract, is acute drug toxicity from a ruptured packet. However, more than 30 years after the initial report of body packing, there is still no definitive treatment protocol for the management of this patient group. The treatment strategy is determined according to the particular condition of the patient and the clinical experience of the treatment center. Surgical intervention is also less common now, due to both the use of improved packaging materials among smugglers and a shift towards a more conservative medical approach. Herein, we report a case of toxicity from ingested packets of cocaine that leaked and, despite surgery, resulted in exitus of the patient.

  14. A Fault Detection Filtering for Networked Control Systems Based on Balanced Reduced-Order

    Directory of Open Access Journals (Sweden)

    Da-Meng Dai

    2015-01-01

    Full Text Available Due to the probability of the packet dropout in the networked control systems, a balanced reduced-order fault detection filter is proposed. In this paper, we first analyze the packet dropout effects in the networked control systems. Then, in order to obtain a robust fault detector for the packet dropout, we use the balanced structure to construct a reduced-order model for residual dynamics. Simulation results are provided to testify the proposed method.

  15. Engineering Issues for an Adaptive Defense Network

    National Research Council Canada - National Science Library

    Piszcz, Alan; Orlans, Nicholas; Eyler-Walker, Zachary; Moore, David

    2001-01-01

    .... The primary issue was the capability to detect and defend against DDoS. Experimentation was performed with a packet filtering firewall, a network Quality of Service manager, multiple DDoS tools, and traffic generation tools...

  16. Zeno dynamics in wave-packet diffraction spreading

    Energy Technology Data Exchange (ETDEWEB)

    Porras, Miguel A. [Departamento de Fisica Aplicada, Universidad Politecnica de Madrid, Rios Rosas 21, ES-28003 Madrid (Spain); Luis, Alfredo; Gonzalo, Isabel [Departamento de Optica, Facultad de Ciencias Fisicas, Universidad Complutense, ES-28040 Madrid (Spain); Sanz, Angel S. [Instituto de Fisica Fundamental-CSIC, Serrano 123, ES-28006 Madrid (Spain)

    2011-11-15

    We analyze a simple and feasible practical scheme displaying Zeno, anti-Zeno, and inverse-Zeno effects in the observation of wave-packet spreading caused by free evolution. The scheme is valid both in spatial diffraction of classical optical waves and in time diffraction of a quantum wave packet. In the optical realization, diffraction spreading is observed by placing slits between a light source and a light-power detector. We show that the occurrence of Zeno or anti-Zeno effects depends just on the frequency of observations between the source and detector. These effects are seen to be related to the diffraction mode theory in Fabry-Perot resonators.

  17. Squeezing a wave packet with an angular-dependent mass

    Energy Technology Data Exchange (ETDEWEB)

    Schmidt, Alexandre G M [Departamento de Ciencias Exatas, Universidade Federal Fluminense, Av. dos Trabalhadores 420, Volta Redonda RJ, CEP 27255-125 (Brazil)], E-mail: agmschmidt@gmail.com, E-mail: agmschmidt@pq.cnpq.br

    2009-06-19

    We present a new effect of position-dependent mass (PDM) systems: the possibility of creating squeezed wave packets at the partial revival times. We solve exactly the PDM Schroedinger equation for the two-dimensional quantum rotor with two effective masses {mu}({theta}), both free and interacting with a uniform electric field, and present their energy eigenvalues and eigenfunctions in terms of Mathieu functions. For the first one, in order to squeeze the wave packet it is necessary to apply an electric field; for the second one such an effect can be achieved without the field.

  18. Squeezing a wave packet with an angular-dependent mass

    International Nuclear Information System (INIS)

    Schmidt, Alexandre G M

    2009-01-01

    We present a new effect of position-dependent mass (PDM) systems: the possibility of creating squeezed wave packets at the partial revival times. We solve exactly the PDM Schroedinger equation for the two-dimensional quantum rotor with two effective masses μ(θ), both free and interacting with a uniform electric field, and present their energy eigenvalues and eigenfunctions in terms of Mathieu functions. For the first one, in order to squeeze the wave packet it is necessary to apply an electric field; for the second one such an effect can be achieved without the field

  19. Gabor Wave Packet Method to Solve Plasma Wave Equations

    International Nuclear Information System (INIS)

    Pletzer, A.; Phillips, C.K.; Smithe, D.N.

    2003-01-01

    A numerical method for solving plasma wave equations arising in the context of mode conversion between the fast magnetosonic and the slow (e.g ion Bernstein) wave is presented. The numerical algorithm relies on the expansion of the solution in Gaussian wave packets known as Gabor functions, which have good resolution properties in both real and Fourier space. The wave packets are ideally suited to capture both the large and small wavelength features that characterize mode conversion problems. The accuracy of the scheme is compared with a standard finite element approach

  20. Improved wavelet packet classification algorithm for vibrational intrusions in distributed fiber-optic monitoring systems

    Science.gov (United States)

    Wang, Bingjie; Pi, Shaohua; Sun, Qi; Jia, Bo

    2015-05-01

    An improved classification algorithm that considers multiscale wavelet packet Shannon entropy is proposed. Decomposition coefficients at all levels are obtained to build the initial Shannon entropy feature vector. After subtracting the Shannon entropy map of the background signal, components of the strongest discriminating power in the initial feature vector are picked out to rebuild the Shannon entropy feature vector, which is transferred to radial basis function (RBF) neural network for classification. Four types of man-made vibrational intrusion signals are recorded based on a modified Sagnac interferometer. The performance of the improved classification algorithm has been evaluated by the classification experiments via RBF neural network under different diffusion coefficients. An 85% classification accuracy rate is achieved, which is higher than the other common algorithms. The classification results show that this improved classification algorithm can be used to classify vibrational intrusion signals in an automatic real-time monitoring system.

  1. A distributed, hardware reconfigurable and packet switched real-time control and data acquisition system

    International Nuclear Information System (INIS)

    Batista, A.J.N.; Combo, A.; Sousa, J.; Varandas, C.A.F.

    2002-01-01

    The architecture of a synchronized event-based control and data acquisition system that aims to improve significantly the performance of actual systems is presented. The design explores recent developments in data transport, signal processing and system synchronization. Data transport between the acquisition, processing and storing devices and at backplane level will be performed by InfiniBand, a low latency packet switched network standard. Data processing algorithms will be performed in a mixture of digital signal processors and reconfigurable field programmable gate arrays. Both devices will be programmed from a descriptive high-level mathematical language. Acquisition synchronization, data stamping and event management will be performed through a specialized low latency synchronous optical network for the time critical signals

  2. Investigation on network utilization efficiency and image transmission time for the PACS network

    International Nuclear Information System (INIS)

    Tawara, K.; Nishihara, E.; Komatsu, K.I.

    1987-01-01

    The authors investigated the following features of a PACS network: (1) network utilization efficiency and (2) image transmission time. They changed the following parameters, which the two items shown above depend on: (1) transfer rate between imaging equipment and network (10 kB/econd-8 MB/second), (2) network transmission speed (100 kB/second-50 MB/second), (3) packet length (10 kB-4 MB), and (4) message length (image data) (64 kB-4 MB). As a result, a conventional-type network cannot meet a need for PACS. To solve this problem, the authors propose a multiplexed network that consists of the high-speed network for image transmission and the conventional speed of control network for commands and shorter messages. If the packet length of the image network is designed to be variable, they can choose an optimum packet length for image transmission

  3. Synchronization, retiming and OTDM of an asynchronous 10 Gigabit Ethernet NRZ packet using a time lens for Terabit Ethernet

    DEFF Research Database (Denmark)

    Hu, Hao; Laguardia Areal, Janaina; Mulvad, Hans Christian Hansen

    2011-01-01

    An asynchronous 10G Ethernet packet is synchronized and retimed to a master clock using a time lens. The NRZ packet is converted into an RZ packet and multiplexed with a serial 1.28 Tb/s signal.......An asynchronous 10G Ethernet packet is synchronized and retimed to a master clock using a time lens. The NRZ packet is converted into an RZ packet and multiplexed with a serial 1.28 Tb/s signal....

  4. Optical frame synchronizer for 10 G Ethernet packets aiming at 1 Tb/s OTDM Ethernet

    DEFF Research Database (Denmark)

    Hu, Hao; Palushani, Evarist; Laguardia Areal, Janaina

    2010-01-01

    Synchronization of 10 G Ethernet packets to a local clock was demonstrated using a phase modulator and a SMF as retiming elements. Error free performances for the synchronized packets with different lengths were achieved.......Synchronization of 10 G Ethernet packets to a local clock was demonstrated using a phase modulator and a SMF as retiming elements. Error free performances for the synchronized packets with different lengths were achieved....

  5. Standard services for the capture, processing, and distribution of packetized telemetry data

    Science.gov (United States)

    Stallings, William H.

    1989-01-01

    Standard functional services for the capture, processing, and distribution of packetized data are discussed with particular reference to the future implementation of packet processing systems, such as those for the Space Station Freedom. The major functions are listed under the following major categories: input processing, packet processing, and output processing. A functional block diagram of a packet data processing facility is presented, showing the distribution of the various processing functions as well as the primary data flow through the facility.

  6. 160 Gbit/s optical packet switching using a silicon chip

    DEFF Research Database (Denmark)

    Hu, Hao; Ji, Hua; Galili, Michael

    2012-01-01

    We have successfully demonstrated 160 Gbit/s all-optical packet switching based on cross-phase modulation using a silicon chip. Error free performance is achieved for the 4-to-1 switched 160 Gbit/s packet.......We have successfully demonstrated 160 Gbit/s all-optical packet switching based on cross-phase modulation using a silicon chip. Error free performance is achieved for the 4-to-1 switched 160 Gbit/s packet....

  7. Optical packet switching in HPC : an analysis of applications performance

    NARCIS (Netherlands)

    Meyer, Hugo; Sancho, Jose Carlos; Mrdakovic, Milica; Miao, Wang; Calabretta, Nicola

    2018-01-01

    Optical Packet Switches (OPS) could provide the needed low latency transmissions in today large data centers. OPS can deliver lower latency and higher bandwidth than traditional electrical switches. These features are needed for parallel High Performance Computing (HPC) applications. For this

  8. The Sphinx and the Pyramids at Giza. Educational Packet.

    Science.gov (United States)

    Gagliano, Sara; Rapport, Wendy

    This packet of materials was created to accompany the exhibit "The Sphinx and the Pyramids: 100 Years of American Archaeology at Giza" at the Semitic Museum of Harvard University. The lessons and teacher's guide focus on the following: (1) "The Mystery of the Secret Tomb" where students take on the role of an archaeologist by…

  9. Simulation of the collapse and dissipation of Langmuir wave packets

    International Nuclear Information System (INIS)

    Newman, D.L.; Winglee, R.M.; Robinson, P.A.; Glanz, J.; Goldman, M.V.

    1990-01-01

    The collapse of isolated Langmuir wave packets is studied numerically in two dimensions using both particle-in-cell (PIC) simulations and by integrating the Zakharov partial differential equations (PDE's). The initial state consists of a localized Langmuir wave packet in an ion background that either is uniform or has a profile representative of the density wells in which wave packets form during strong plasma turbulence. Collapse thresholds are determined numerically and compared to analytical estimates. A model in which Langmuir damping is significantly stronger than Landau damping is constructed which, when included in the PDE simulations, yields good agreement with the collapse dynamics observed in PIC simulations for wave packets with initial wave energy densities small compared to the thermal level. For more intense initial Langmuir fields, collapse is arrested in PIC simulations at lower field strengths than in PDE simulations. Neither nonlinear saturation of the density perturbation nor fluid electron nonlinearities can account for the difference between simulation methods in this regime. However, at these wave levels inhomogeneous electron heating and coherent jets of transit-time accelerated electrons in phase space are observed, resulting in further enhancement of wave damping and the consequent reduction of fields in the PIC simulations

  10. Comparison of Deep Packet Inspection (DPI) Tools for Traffic Classification

    DEFF Research Database (Denmark)

    Bujlow, Tomasz; Carela-Español, Valentín; Barlet-Ros, Pere

    the researchers do not only have the full payloads, but also they are provided the information which application created the flow. Therefore, the dataset is useful for testing Deep Packet Inspection (DPI) tools, as well as statistical, and port-based classifiers. The dataset was created in a fully manual way...

  11. Customized lifting multiwavelet packet information entropy for equipment condition identification

    International Nuclear Information System (INIS)

    Chen, Jinglong; Zi, Yanyang; He, Zhengjia; Chen, Xuefeng; Zuo, Ming J; Yuan, Jing

    2013-01-01

    Condition identification of mechanical equipment from vibration measurement data is significant to avoid economic loss caused by unscheduled breakdowns and catastrophic accidents. However, this task still faces challenges due to the complexity of equipment and the harsh environment. This paper provides a possibility for equipment condition identification by proposing a method called customized lifting multiwavelet packet information entropy. Benefiting from the properties of multi-resolution analysis and multiple wavelet basis functions, the multiwavelet method has advantages in characterizing non-stationary vibration signals. In order to realize the accurate detection and identification of the condition features, a customized lifting multiwavelet packet is constructed via a multiwavelet lifting scheme. Then the vibration signal from the mechanical equipment is processed by the customized lifting multiwavelet packet transform. The relative energy in each frequency band of the multiwavelet packet transform coefficients that equals a percentage of the whole signal energy is taken as the probability. The normalized information entropy is obtained based on the relative energy to describe the condition of a mechanical system. The proposed method is applied to the condition identification of a rolling mill and a demountable disk–drum aero-engine. The results support the feasibility of the proposed method in equipment condition identification. (paper)

  12. Production of a tracer packet of heavier rare earth elements

    International Nuclear Information System (INIS)

    Lahiri, S.; Nayak, D.; Maji, S.

    2004-01-01

    Production of a tracer packet of heavier rare earth elements containing carrier-free radionuclides of 153,155 Tb, 153,155,157 Dy, 159 Ho, 159,161 Er, 161 Tm produced by medium energy 7 Li and 12 C irradiation on an europium oxide target and the subsequent separation of bulk europium from the carrier-free products is described. (author)

  13. Angular momentum transport with twisted exciton wave packets

    Science.gov (United States)

    Zang, Xiaoning; Lusk, Mark T.

    2017-10-01

    A chain of cofacial molecules with CN or CN h symmetry supports excitonic states with a screwlike structure. These can be quantified with the combination of an axial wave number and an azimuthal winding number. Combinations of these states can be used to construct excitonic wave packets that spiral down the chain with well-determined linear and angular momenta. These twisted exciton wave packets can be created and annihilated using laser pulses, and their angular momentum can be optically modified during transit. This allows for the creation of optoexcitonic circuits in which information, encoded in the angular momentum of light, is converted into excitonic wave packets that can be manipulated, transported, and then reemitted. A tight-binding paradigm is used to demonstrate the key ideas. The approach is then extended to quantify the evolution of twisted exciton wave packets in a many-body, multilevel time-domain density functional theory setting. In both settings, numerical methods are developed that allow the site-to-site transfer of angular momentum to be quantified.

  14. a pyramid algorithm for the haar discrete wavelet packet transform

    African Journals Online (AJOL)

    PROF EKWUEME

    computer-aided signal processing of non-stationary signals, this paper develops a pyramid algorithm for the discrete wavelet packet ... Edith T. Luhanga, School of Computational and Communication Sciences and Engineering, Nelson Mandela African. Institute of ..... Mathematics, Washington University. 134. EDITH T.

  15. A CURRICULUM FOR ENGLISH, STUDENT PACKET, GRADE 9.

    Science.gov (United States)

    Nebraska Univ., Lincoln. Curriculum Development Center.

    THE FIRST UNIT OF THE STUDENT PACKET FOR GRADE NINE OF THE NEBRASKA ENGLISH CURRICULUM IS A STUDY OF THE RELATIONSHIPS WHICH EXIST BETWEEN AUTHOR AND AUDIENCE, AND AN EXAMINATION OF THE EPIGRAM, LIMERICK, PARABLE, FABLE, AND ODE. WITH THIS BACKGROUND, STUDENTS CONSIDER "ON AVARICE" AND "ANIMAL FARM" AS EXAMPLES OF FORMAL AND…

  16. State reconstruction of one-dimensional wave packets

    Science.gov (United States)

    Krähmer, D. S.; Leonhardt, U.

    1997-12-01

    We review and analyze the method [U. Leonhardt, M.G. Raymer: Phys. Rev. Lett. 76, 1985 (1996)] for quantum-state reconstruction of one-dimensional non-relativistic wave packets from position observations. We illuminate the theoretical background of the technique and show how to extend the procedure to the continuous part of the spectrum.

  17. INTERNET TRAFFIC AND PACKET ROUND TRIP DELAY SELF ...

    African Journals Online (AJOL)

    object of our interest)- is preserved with respect to scaling in space and/or ... models and the standard models for packet traffic considered in the ... tlle structure of the Internet, but failed to exhaustively ... the vehicle of Sel.fSimilar processes ...

  18. Quantum wave-packet revivals in circular billiards

    International Nuclear Information System (INIS)

    Robinett, R.W.; Heppelmann, S.

    2002-01-01

    We examine the long-term time dependence of Gaussian wave packets in a circular infinite well (billiard) system and find that there are approximate revivals. For the special case of purely m=0 states (central wave packets with no momentum) the revival time is T rev (m=0) =8μR 2 /(ℎ/2π)π, where μ is the mass of the particle, and the revivals are almost exact. For all other wave packets, we find that T rev (m≠0) =(π 2 /2)T rev (m=0) ≅5T rev (m=0) and the nature of the revivals becomes increasingly approximate as the average angular momentum or number of m≠0 states is increased. The dependence of the revival structure on the initial position, energy, and angular momentum of the wave packet and the connection to the energy spectrum is discussed in detail. The results are also compared to two other highly symmetrical two-dimensional infinite well geometries with exact revivals, namely, the square and equilateral triangle billiards. We also show explicitly how the classical periodicity for closed orbits in a circular billiard arises from the energy eigenvalue spectrum, using a WKB analysis

  19. General writing-information packet for the environmental impact project

    International Nuclear Information System (INIS)

    Raaen, H.P.

    1975-02-01

    The information packet was prepared primarily for internal use at Holifield National Laboratory. The contents include suggestions to authors of environmental statements; format of environmental statements; formats of references given in environmental statements; preparation of SELECTED BIBLIOGRAPHY; troublesome words; glossary; abbreviations, initialisms, and symbols; and MT/ST taping procedure. (U.S.)

  20. Solar Energy Education Packet for Elementary & Secondary Students.

    Science.gov (United States)

    Center for Renewable Resources, Washington, DC.

    The arrangement of this packet is essentially evolutionary, with a conscious effort to alternate reading assignments, activities and experiments. It begins with solar energy facts and terminology as background to introduce the reader to basic concepts. It progresses into a discussion of passive solar systems. This is followed by several projects…

  1. Solar Energy Education Packet for Elementary & Secondary Students. Revised Edition.

    Science.gov (United States)

    Center for Renewable Resources, Washington, DC.

    The arrangement of this packet is essentially evolutionary, with a conscious effort to alternate reading assignments, activities and experiments. It begins with solar energy facts and terminology as background to introduce the reader to basic concepts. It progresses into a discussion of passive solar systems. This is followed by several projects…

  2. Random access with adaptive packet aggregation in LTE/LTE-A.

    Science.gov (United States)

    Zhou, Kaijie; Nikaein, Navid

    While random access presents a promising solution for efficient uplink channel access, the preamble collision rate can significantly increase when massive number of devices simultaneously access the channel. To address this issue and improve the reliability of the random access, an adaptive packet aggregation method is proposed. With the proposed method, a device does not trigger a random access for every single packet. Instead, it starts a random access when the number of aggregated packets reaches a given threshold. This method reduces the packet collision rate at the expense of an extra latency, which is used to accumulate multiple packets into a single transmission unit. Therefore, the tradeoff between packet loss rate and channel access latency has to be carefully selected. We use semi-Markov model to derive the packet loss rate and channel access latency as functions of packet aggregation number. Hence, the optimal amount of aggregated packets can be found, which keeps the loss rate below the desired value while minimizing the access latency. We also apply for the idea of packet aggregation for power saving, where a device aggregates as many packets as possible until the latency constraint is reached. Simulations are carried out to evaluate our methods. We find that the packet loss rate and/or power consumption are significantly reduced with the proposed method.

  3. Joint Connection and Packet level Analysis in W-CDMA Radio Interface

    DEFF Research Database (Denmark)

    Benetis, Vilius; Popova, Larissa; Iversen, Villy Bæk

    2007-01-01

    algorithm which defines the feasible state space at packet level. At packet level we take into consideration wireless interference (soft blocking). The traffic is modeled as multi-rate Binomial-Poisson-Pascal (BPP-) traffic at connection level and on-off traffic at packet level. We obtain individual...

  4. Strongly nonlinear evolution of low-frequency wave packets in a dispersive plasma

    Science.gov (United States)

    Vasquez, Bernard J.

    1993-01-01

    The evolution of strongly nonlinear, strongly modulated wave packets is investigated in a dispersive plasma using a hybrid numerical code. These wave packets have amplitudes exceeding the strength of the external magnetic field, along which they propagate. Alfven (left helicity) wave packets show strong steepening for p Schrodinger (DNLS) equation.

  5. Vector Network Coding

    OpenAIRE

    Ebrahimi, Javad; Fragouli, Christina

    2010-01-01

    We develop new algebraic algorithms for scalar and vector network coding. In vector network coding, the source multicasts information by transmitting vectors of length L, while intermediate nodes process and combine their incoming packets by multiplying them with L X L coding matrices that play a similar role as coding coefficients in scalar coding. Our algorithms for scalar network jointly optimize the employed field size while selecting the coding coefficients. Similarly, for vector co...

  6. Vector Network Coding Algorithms

    OpenAIRE

    Ebrahimi, Javad; Fragouli, Christina

    2010-01-01

    We develop new algebraic algorithms for scalar and vector network coding. In vector network coding, the source multicasts information by transmitting vectors of length L, while intermediate nodes process and combine their incoming packets by multiplying them with L x L coding matrices that play a similar role as coding c in scalar coding. Our algorithms for scalar network jointly optimize the employed field size while selecting the coding coefficients. Similarly, for vector coding, our algori...

  7. Incentivizing and Evaluating Internet-Wide Network Measurements

    Science.gov (United States)

    2014-03-01

    Romania . . . . . . . . . . . . . . . . . . . . . . 62 Figure A.20 Cumulative SCR for Egypt . . . . . . . . . . . . . . . . . . . . . . . 63 Figure A...defined in RFC 1918 [29] and these packets should never be routed in the public Internet. These packets, however, are often filtered in the network core...Turkey, Singapore, Russia, Romania , Pakistan, Philippines, Netherlands, Indonesia, Hun- gary, Guatemala, Finland, Denmark, Switzerland, Brazil

  8. Stateless Malware Packet Detection by Incorporating Naive Bayes with Known Malware Signatures

    Directory of Open Access Journals (Sweden)

    Ismahani Ismail

    2014-01-01

    Full Text Available Malware detection done at the network infrastructure level is still an open research problem ,considering the evolution of malwares and high detection accuracy needed to detect these threats. Content based classification techniques have been proven capable of detecting malware without matching for malware signatures. However, the performance of the classification techniques depends on observed training samples. In this paper, a new detection method that incorporates Snort malware signatures into Naive Bayes model training is proposed. Through experimental work, we prove that the proposed work results in low features search space for effective detection at the packet level. This paper also demonstrates the viability of detecting malware at the stateless level (using packets as well as at the stateful level (using TCP byte stream. The result shows that it is feasible to detect malware at the stateless level with similar accuracy to the stateful level, thus requiring minimal resource for implementation on middleboxes. Stateless detection can give a better protection to end users by detecting malware on middleboxes without having to reconstruct stateful sessions and before malwares reach the end users.

  9. Modeling On-Body DTN Packet Routing Delay in the Presence of Postural Disconnections

    Directory of Open Access Journals (Sweden)

    Taghizadeh Mahmoud

    2011-01-01

    Full Text Available This paper presents a stochastic modeling framework for store-and-forward packet routing in Wireless Body Area Networks (WBAN with postural partitioning. A prototype WBANs has been constructed for experimentally characterizing and capturing on-body topology disconnections in the presence of ultrashort range radio links, unpredictable RF attenuation, and human postural mobility. Delay modeling techniques for evaluating single-copy on-body DTN routing protocols are then developed. End-to-end routing delay for a series of protocols including opportunistic, randomized, and two other mechanisms that capture multiscale topological localities in human postural movements have been evaluated. Performance of the analyzed protocols are then evaluated experimentally and via simulation to compare with the results obtained from the developed model. Finally, a mechanism for evaluating the topological importance of individual on-body sensor nodes is developed. It is shown that such information can be used for selectively reducing the on-body sensor-count without substantially sacrificing the packet delivery delay.

  10. Modeling On-Body DTN Packet Routing Delay in the Presence of Postural Disconnections.

    Science.gov (United States)

    Quwaider, Muhannad; Taghizadeh, Mahmoud; Biswas, Subir

    2011-01-01

    This paper presents a stochastic modeling framework for store-and-forward packet routing in Wireless Body Area Networks ( WBAN ) with postural partitioning. A prototype WBANs has been constructed for experimentally characterizing and capturing on-body topology disconnections in the presence of ultrashort range radio links, unpredictable RF attenuation, and human postural mobility. Delay modeling techniques for evaluating single-copy on-body DTN routing protocols are then developed. End-to-end routing delay for a series of protocols including opportunistic, randomized, and two other mechanisms that capture multiscale topological localities in human postural movements have been evaluated. Performance of the analyzed protocols are then evaluated experimentally and via simulation to compare with the results obtained from the developed model. Finally, a mechanism for evaluating the topological importance of individual on-body sensor nodes is developed. It is shown that such information can be used for selectively reducing the on-body sensor-count without substantially sacrificing the packet delivery delay.

  11. Enhancing Sensor Network Data Quality via Collaborated Circuit and Network Operations

    Directory of Open Access Journals (Sweden)

    Lucas Vespa

    2013-04-01

    Full Text Available In many applications, the quality of data gathered by sensor networks is directly related to the signal-to-noise ratio (SNR of the sensor data being transmitted in the networks. Different from the SNR that is often used in measuring the quality of communication links, the SNR used in this work measures how accurately the data in the network packets represent the physical parameters being sensed. Hence, the signal here refers to the physical parameters that are being monitored by sensor networks; the noise is due to environmental interference and circuit noises at sensor nodes, and packet loss during network transmission. While issues affecting SNR at sensor nodes have been intensively investigated, the impact of network packet loss on data SNR has not attracted significant attention in sensor network design. This paper investigates the impact of packet loss on sensor network data SNR and shows that data SNR is dramatically affected by network packet loss. A data quality metric, based on data SNR, is developed and a cross-layer adaptive scheme is presented to minimize data quality degradation in congested sensor networks. The proposed scheme consists of adaptive downsampling and bit truncation at sensor nodes and intelligent traffic management techniques at the network level. Simulation results are presented to demonstrate the validity and effectiveness of the proposed techniques.

  12. Tunable Sparse Network Coding for Multicast Networks

    DEFF Research Database (Denmark)

    Feizi, Soheil; Roetter, Daniel Enrique Lucani; Sørensen, Chres Wiant

    2014-01-01

    This paper shows the potential and key enabling mechanisms for tunable sparse network coding, a scheme in which the density of network coded packets varies during a transmission session. At the beginning of a transmission session, sparsely coded packets are transmitted, which benefits decoding...... complexity. At the end of a transmission, when receivers have accumulated degrees of freedom, coding density is increased. We propose a family of tunable sparse network codes (TSNCs) for multicast erasure networks with a controllable trade-off between completion time performance to decoding complexity...... a mechanism to perform efficient Gaussian elimination over sparse matrices going beyond belief propagation but maintaining low decoding complexity. Supporting simulation results are provided showing the trade-off between decoding complexity and completion time....

  13. Implementation of a network level protocol on a GIXINET type local network

    International Nuclear Information System (INIS)

    Loeuillet, J.L.

    1987-11-01

    The installation of a communication system for transferring results from several experiment laboratories to a computing center is described. The objectives of a useful bit rate of 24 kbs, low connection cost and simple infrastructure, extension of the network to 4 buildings situated within a radius of 300m, and connection in the most standardized fashion possible are attained by using the GIXINET local network and adopting the X25 packet protocol. Bit rates of 17.2 kbs for standard 128 octet packets, and 44 kbs for nonstandard packets (776 octets in this case) [fr

  14. Compromises Between Quality of Service Metrics and Energy Consumption of Hierarchical and Flat Routing Protocols for Wireless Sensors Network

    Directory of Open Access Journals (Sweden)

    Abdelbari BEN YAGOUTA

    2016-11-01

    Full Text Available Wireless Sensor Network (WSN is wireless network composed of spatially distributed and tiny autonomous nodes, which cooperatively monitor physical or environmental conditions. Among the concerns of these networks is prolonging the lifetime by saving nodes energy. There are several protocols specially designed for WSNs based on energy conservation. However, many WSNs applications require QoS (Quality of Service criteria, such as latency, reliability and throughput. In this paper, we will compare three routing protocols for wireless sensors network LEACH (Low Energy Adaptive Clustering Hierarchy, AODV (Ad hoc on demand Distance Vector and LABILE (Link Quality-Based Lexical Routing using Castalia simulator in terms of energy consumption, throughput, reliability and latency time of packets received by sink under different conditions to determinate the best configurations that offers the most suitable compromises between energy conservation and all QoS metrics for each routing protocols. The results show that, the best configurations that offer the suitable compromises between energy conservation and all QoS metrics is a large number of deployed nodes with low packet rate for LEACH (300 nodes and 1 packet/s, a medium number of deployed nodes with low packet rate For AODV (100 nodes and 1 packet/s and a very low nodes density with low packet rate for LABILE (50 nodes and 1 packet/s.

  15. Energy and Information Transfer Via Coherent Exciton Wave Packets

    Science.gov (United States)

    Zang, Xiaoning

    Electronic excitons are bound electron-hole states that are generated when light interacts with matter. Such excitations typically entangle with phonons and rapidly decohere; the resulting electronic state dynamics become diffusive as a result. However, if the exciton-phonon coupling can be reduced, it may be possible to construct excitonic wave packets that offer a means of efficiently transmitting information and energy. This thesis is a combined theory/computation investigation to design condensed matter systems which support the requisite coherent transport. Under the idealizing assumption that exciton-phonon entanglement could be completely suppressed, the majority of this thesis focuses on the creation and manipulation of exciton wave packets in quasi-one-dimensional systems. While each site could be a silicon quantum dot, the actual implementation focused on organic molecular assemblies for the sake of computational simplicity, ease of experimental implementation, potential for coherent transport, and promise because of reduced structural uncertainty. A laser design was derived to create exciton wave packets with tunable shape and speed. Quantum interference was then exploited to manipulate these packets to block, pass, and even dissociate excitons based on their energies. These developments allow exciton packets to be considered within the arena of quantum information science. The concept of controllable excitonic wave packets was subsequently extended to consider molecular designs that allow photons with orbital angular momentum to be absorbed to create excitons with a quasi-angular momentum of their own. It was shown that a well-defined measure of topological charge is conserved in such light-matter interactions. Significantly, it was also discovered that such molecules allow photon angular momenta to be combined and later emitted. This amounts to a new way of up/down converting photonic angular momentum without relying on nonlinear optical materials. The

  16. 1×4 Optical packet switching of variable length 640 Gbit/s data packets using in-band optical notch-filter labeling

    DEFF Research Database (Denmark)

    Medhin, Ashenafi Kiros; Kamchevska, Valerija; Galili, Michael

    2014-01-01

    We experimentally perform 1×4 optical packet switching of variable length 640 Gbit/s OTDM data packets using in-band notch-filter labeling with only 2.7-dB penalty. Up to 8 notches are employed to demonstrate scalability of the labeling scheme to 1×256 switching operation.......We experimentally perform 1×4 optical packet switching of variable length 640 Gbit/s OTDM data packets using in-band notch-filter labeling with only 2.7-dB penalty. Up to 8 notches are employed to demonstrate scalability of the labeling scheme to 1×256 switching operation....

  17. Flow whitelisting in SCADA networks

    DEFF Research Database (Denmark)

    Barbosa, Rafael Ramos Regis; Sadre, Ramin; Pras, Aiko

    2013-01-01

    and the Internet. This paper describes an approach for improving the security of SCADA networks using flow whitelisting. A flow whitelist describes legitimate traffic based on four properties of network packets: client address, server address, server-side port and transport protocol. The proposed approach...

  18. Description and Simulation of a Fast Packet Switch Architecture for Communication Satellites

    Science.gov (United States)

    Quintana, Jorge A.; Lizanich, Paul J.

    1995-01-01

    The NASA Lewis Research Center has been developing the architecture for a multichannel communications signal processing satellite (MCSPS) as part of a flexible, low-cost meshed-VSAT (very small aperture terminal) network. The MCSPS architecture is based on a multifrequency, time-division-multiple-access (MF-TDMA) uplink and a time-division multiplex (TDM) downlink. There are eight uplink MF-TDMA beams, and eight downlink TDM beams, with eight downlink dwells per beam. The information-switching processor, which decodes, stores, and transmits each packet of user data to the appropriate downlink dwell onboard the satellite, has been fully described by using VHSIC (Very High Speed Integrated-Circuit) Hardware Description Language (VHDL). This VHDL code, which was developed in-house to simulate the information switching processor, showed that the architecture is both feasible and viable. This paper describes a shared-memory-per-beam architecture, its VHDL implementation, and the simulation efforts.

  19. FAST TCP over optical burst switched networks: Modeling and stability analysis

    KAUST Repository

    Shihada, Basem; El-Ferik, Sami; Ho, Pin-Han

    2013-01-01

    congestion-control mechanism in bufferless Optical Burst Switched Networks (OBS). The paper first shows that random burst contentions are essential to stabilize the network, but cause throughput degradation in FAST TCP flows when a burst with all the packets

  20. Very low bit rate voice for packetized mobile applications

    International Nuclear Information System (INIS)

    Knittle, C.D.; Malone, K.T.

    1991-01-01

    This paper reports that transmitting digital voice via packetized mobile communications systems that employ relatively short packet lengths and narrow bandwidths often necessitates very low bit rate coding of the voice data. Sandia National Laboratories is currently developing an efficient voice coding system operating at 800 bits per second (bps). The coding scheme is a modified version of the 2400 bps NSA LPC-10e standard. The most significant modification to the LPC-10e scheme is the vector quantization of the line spectrum frequencies associated with the synthesis filters. An outline of a hardware implementation for the 800 bps coder is presented. The speech quality of the coder is generally good, although speaker recognition is not possible. Further research is being conducted to reduce the memory requirements and complexity of the vector quantizer, and to increase the quality of the reconstructed speech. This work may be of use dealing with nuclear materials

  1. Cherenkov Radiation Control via Self-accelerating Wave-packets.

    Science.gov (United States)

    Hu, Yi; Li, Zhili; Wetzel, Benjamin; Morandotti, Roberto; Chen, Zhigang; Xu, Jingjun

    2017-08-18

    Cherenkov radiation is a ubiquitous phenomenon in nature. It describes electromagnetic radiation from a charged particle moving in a medium with a uniform velocity larger than the phase velocity of light in the same medium. Such a picture is typically adopted in the investigation of traditional Cherenkov radiation as well as its counterparts in different branches of physics, including nonlinear optics, spintronics and plasmonics. In these cases, the radiation emitted spreads along a "cone", making it impractical for most applications. Here, we employ a self-accelerating optical pump wave-packet to demonstrate controlled shaping of one type of generalized Cherenkov radiation - dispersive waves in optical fibers. We show that, by tuning the parameters of the wave-packet, the emitted waves can be judiciously compressed and focused at desired locations, paving the way to such control in any physical system.

  2. Pump-dump iterative squeezing of vibrational wave packets.

    Science.gov (United States)

    Chang, Bo Y; Sola, Ignacio R

    2005-12-22

    The free motion of a nonstationary vibrational wave packet in an electronic potential is a source of interesting quantum properties. In this work we propose an iterative scheme that allows continuous stretching and squeezing of a wave packet in the ground or in an excited electronic state, by switching the wave function between both potentials with pi pulses at certain times. Using a simple model of displaced harmonic oscillators and delta pulses, we derive the analytical solution and the conditions for its possible implementation and optimization in different molecules and electronic states. We show that the main constraining parameter is the pulse bandwidth. Although in principle the degree of squeezing (or stretching) is not bounded, the physical resources increase quadratically with the number of iterations, while the achieved squeezing only increases linearly.

  3. Service Time Analysis for Secondary Packet Transmission with Adaptive Modulation

    KAUST Repository

    Wang, Wen-Jing; Usman, Muneer; Yang, Hong-Chuan; Alouini, Mohamed-Slim

    2017-01-01

    Cognitive radio communications can opportunistically access underutilized spectrum for emerging wireless applications. With interweave cognitive implementation, secondary user transmits only if primary user does not occupy the channel and waits for transmission otherwise. Therefore, secondary packet transmission involves both transmission time and waiting time. The resulting extended delivery time (EDT) is critical to the throughput analysis of secondary system. In this paper, we study the EDT of secondary packet transmission with adaptive modulation under interweave implementation to facilitate the delay and throughput analysis of such cognitive radio system. In particular, we propose an analytical framework to derive the probability density functions of EDT considering random-length transmission and waiting slots. We also present selected numerical results to illustrate the mathematical formulations and to verify our analytical approach.

  4. Service Time Analysis for Secondary Packet Transmission with Adaptive Modulation

    KAUST Repository

    Wang, Wen-Jing

    2017-05-12

    Cognitive radio communications can opportunistically access underutilized spectrum for emerging wireless applications. With interweave cognitive implementation, secondary user transmits only if primary user does not occupy the channel and waits for transmission otherwise. Therefore, secondary packet transmission involves both transmission time and waiting time. The resulting extended delivery time (EDT) is critical to the throughput analysis of secondary system. In this paper, we study the EDT of secondary packet transmission with adaptive modulation under interweave implementation to facilitate the delay and throughput analysis of such cognitive radio system. In particular, we propose an analytical framework to derive the probability density functions of EDT considering random-length transmission and waiting slots. We also present selected numerical results to illustrate the mathematical formulations and to verify our analytical approach.

  5. Impact of packet losses in scalable 3D holoscopic video coding

    Science.gov (United States)

    Conti, Caroline; Nunes, Paulo; Ducla Soares, Luís.

    2014-05-01

    Holoscopic imaging became a prospective glassless 3D technology to provide more natural 3D viewing experiences to the end user. Additionally, holoscopic systems also allow new post-production degrees of freedom, such as controlling the plane of focus or the viewing angle presented to the user. However, to successfully introduce this technology into the consumer market, a display scalable coding approach is essential to achieve backward compatibility with legacy 2D and 3D displays. Moreover, to effectively transmit 3D holoscopic content over error-prone networks, e.g., wireless networks or the Internet, error resilience techniques are required to mitigate the impact of data impairments in the user quality perception. Therefore, it is essential to deeply understand the impact of packet losses in terms of decoding video quality for the specific case of 3D holoscopic content, notably when a scalable approach is used. In this context, this paper studies the impact of packet losses when using a three-layer display scalable 3D holoscopic video coding architecture previously proposed, where each layer represents a different level of display scalability (i.e., L0 - 2D, L1 - stereo or multiview, and L2 - full 3D holoscopic). For this, a simple error concealment algorithm is used, which makes use of inter-layer redundancy between multiview and 3D holoscopic content and the inherent correlation of the 3D holoscopic content to estimate lost data. Furthermore, a study of the influence of 2D views generation parameters used in lower layers on the performance of the used error concealment algorithm is also presented.

  6. Uplink Packet-Data Scheduling in DS-CDMA Systems

    Science.gov (United States)

    Choi, Young Woo; Kim, Seong-Lyun

    In this letter, we consider the uplink packet scheduling for non-real-time data users in a DS-CDMA system. As an effort to jointly optimize throughput and fairness, we formulate a time-span minimization problem incorporating the time-multiplexing of different simultaneous transmission schemes. Based on simple rules, we propose efficient scheduling algorithms and compare them with the optimal solution obtained by linear programming.

  7. Information Processing Techniques Program. Volume I. Packet Speech Systems Technology

    Science.gov (United States)

    1980-09-30

    Itindsign has litt-rn vt-tntit-r aliti sill dI- ditiibuted trrni cparat- tintr aisa ithnnin ITtc-i A. Packet Vttice Terminal As Iprt- iouisik rtrtteti tin...September 1980. FO1M 1473 EDITION OF I NOV 65 IS OBSOLETEDD I JAN 73 UNCLA.SSI F[IF ) SECURITY CLASSIFICATION OF THIS PAGE (Ibmn Data fntew-d)

  8. Universal potential-barrier penetration by initially confined wave packets

    International Nuclear Information System (INIS)

    Granot, Er'el; Marchewka, Avi

    2007-01-01

    The dynamics of an initially sharp-boundary wave packet in the presence of an arbitrary potential barrier is investigated. It is shown that the penetration through the barrier is universal in the sense that it depends only on the values of the wave function and its derivatives at the boundary. The dependence on the derivatives vanishes at long distances from the barrier, where the dynamics is governed solely by the initial value of the wave function at the boundary

  9. Universal potential-barrier penetration by initially confined wave packets

    Science.gov (United States)

    Granot, Er'El; Marchewka, Avi

    2007-07-01

    The dynamics of an initially sharp-boundary wave packet in the presence of an arbitrary potential barrier is investigated. It is shown that the penetration through the barrier is universal in the sense that it depends only on the values of the wave function and its derivatives at the boundary. The dependence on the derivatives vanishes at long distances from the barrier, where the dynamics is governed solely by the initial value of the wave function at the boundary.

  10. Wireless network interface energy consumption implications of popular streaming formats

    Science.gov (United States)

    Chandra, Surendar

    2001-12-01

    With the proliferation of mobile streaming multimedia, available battery capacity constrains the end-user experience. Since streaming applications tend to be long running, wireless network interface card's (WNIC) energy consumption is particularly an acute problem. In this work, we explore the WNIC energy consumption implications of popular multimedia streaming formats from Microsoft (Windows media), Real (Real media) and Apple (Quick Time). We investigate the energy consumption under varying stream bandwidth and network loss rates. We also explore history-based client-side strategies to reduce the energy consumed by transitioning the WNICs to a lower power consuming sleep state. We show that Microsoft media tends to transmit packets at regular intervals; streams optimized for 28.8 Kbps can save over 80% in energy consumption with 2% data loss. A high bandwidth stream (768 Kbps) can still save 57% in energy consumption with less than 0.3% data loss. For high bandwidth streams, Microsoft media exploits network-level packet fragmentation, which can lead to excessive packet loss (and wasted energy) in a lossy network. Real stream packets tend to be sent closer to each other, especially at higher bandwidths. Quicktime packets sometimes arrive in quick succession; most likely an application level fragmentation mechanism. Such packets are harder to predict at the network level without understanding the packet semantics.

  11. A Review of the Topologies Used in Smart Water Meter Networks: A Wireless Sensor Network Application

    Directory of Open Access Journals (Sweden)

    Jaco Marais

    2016-01-01

    Full Text Available This paper presents several proposed and existing smart utility meter systems as well as their communication networks to identify the challenges of creating scalable smart water meter networks. Network simulations are performed on 3 network topologies (star, tree, and mesh to determine their suitability for smart water meter networks. The simulations found that once a number of nodes threshold is exceeded the network’s delay increases dramatically regardless of implemented topology. This threshold is at a relatively low number of nodes (50 and the use of network topologies such as tree or mesh helps alleviate this problem and results in lower network delays. Further simulations found that the successful transmission of application layer packets in a 70-end node tree network can be improved by 212% when end nodes only transmit data to their nearest router node. The relationship between packet success rate and different packet sizes was also investigated and reducing the packet size with a factor of 16 resulted in either 156% or 300% increases in the amount of successfully received packets depending on the network setup.

  12. On Maximizing the Throughput of Packet Transmission under Energy Constraints.

    Science.gov (United States)

    Wu, Weiwei; Dai, Guangli; Li, Yan; Shan, Feng

    2018-06-23

    More and more Internet of Things (IoT) wireless devices have been providing ubiquitous services over the recent years. Since most of these devices are powered by batteries, a fundamental trade-off to be addressed is the depleted energy and the achieved data throughput in wireless data transmission. By exploiting the rate-adaptive capacities of wireless devices, most existing works on energy-efficient data transmission try to design rate-adaptive transmission policies to maximize the amount of transmitted data bits under the energy constraints of devices. Such solutions, however, cannot apply to scenarios where data packets have respective deadlines and only integrally transmitted data packets contribute. Thus, this paper introduces a notion of weighted throughput, which measures how much total value of data packets are successfully and integrally transmitted before their own deadlines. By designing efficient rate-adaptive transmission policies, this paper aims to make the best use of the energy and maximize the weighted throughput. What is more challenging but with practical significance, we consider the fading effect of wireless channels in both offline and online scenarios. In the offline scenario, we develop an optimal algorithm that computes the optimal solution in pseudo-polynomial time, which is the best possible solution as the problem undertaken is NP-hard. In the online scenario, we propose an efficient heuristic algorithm based on optimal properties derived for the optimal offline solution. Simulation results validate the efficiency of the proposed algorithm.

  13. Square-integrable wave packets from the Volkov solutions

    International Nuclear Information System (INIS)

    Zakowicz, Stephan

    2005-01-01

    Rigorous mathematical proofs of some properties of the Volkov solutions are presented, which describe the motion of a relativistic charged Dirac particle in a classical, plane electromagnetic wave. The Volkov solutions are first rewritten in a convenient form, which clearly reveals some of the symmetries of the underlying Dirac equation. Assuming continuity and boundedness of the electromagnetic vector potential, it is shown how one may construct square-integrable wave packets from momentum distributions in the space C 0 ∞ (R 3 ) 4 . If, in addition, the vector potential is C 1 and the derivative is bounded, these wave packets decay in space faster than any polynomial and fulfill the Dirac equation. The mapping which takes momentum distributions into wave packets is shown to be isometric with respect to the L 2 (R 3 ) 4 norm and may therefore be continuously extended to a mapping from L 2 (R 3 ) 4 . For a momentum function in L 1 (R 3 ) 4 intersection L 2 (R 3 ) 4 , an integral representation of this extension is presented

  14. Modelling Packet Departure Times using a Known PDF

    Directory of Open Access Journals (Sweden)

    Stanislav Klucik

    2014-01-01

    Full Text Available This paper deals with IPTV traffic source modelling and describes a packet generator based on a known probability density function which is measured and formed from a histogram. Histogram based probability density functions destroy an amount of information, because classes used to form the histogram often cover significantly more events than one. In this work, we propose an algorithm to generate far more output states of random variable X than the input probability distribution function is made from. In this generator is assumed that all IPTV packets of the same video stream are the same length. Therefore, only packet times are generated. These times are generated using the measured normalized histogram that is converted to a cumulative distribution function which acts as a finite number of states that can be addressed. To address these states we use an ON/OFF model that is driven by an uniform random number generator in (0, 1. When a state is chosen then the resulting value is equal to a histogram class. To raise the number of possible output states of the random variable X, we propose to use an uniform random number generator that generates numbers within the range of the chosen histogram class. This second uniform random number generator assures that the number of output states is far more larger than the number of histogram classes.

  15. Square-Integrable Wave Packets from the Volkov Solutions

    CERN Document Server

    Zakowicz, S

    2004-01-01

    Rigorous mathematical proofs of some properties of the Volkov solutions are presented, which describe the motion of a relativistic charged Dirac particle in a classical, plane electromagnetic wave. The Volkov solutions are first rewritten in a convenient form, which clearly reveals some of the symmetries of the underlying Dirac equation. Assuming continuity and boundedness of the electromagnetic vector potential, it is shown how one may construct square-integrable wave packets from momentum distributions in the space $\\mathcal{C}^{\\infty}_0(\\mathbb{R}^3)^4$. If, in addition, the vector potential is $\\mathcal{C}^1$ and the derivative is bounded, these wave packets decay in space faster than any polynomial and fulfill the Dirac equation. The mapping which takes momentum distributions into wave packets is shown to be isometric with respect to the $L^2(\\mathbb{R}^3)^4$ norm and may therefore be continuously extended to a mapping from $L^2(\\mathbb{R}^3)^4$. For a momen! tum function in $L^1(\\mathbb{R}^3)^4 \\cap L^...

  16. Efficient incremental relaying for packet transmission over fading channels

    KAUST Repository

    Fareed, Muhammad Mehboob

    2014-07-01

    In this paper, we propose a novel relaying scheme for packet transmission over fading channels, which improves the spectral efficiency of cooperative diversity systems by utilizing limited feedback from the destination. Our scheme capitalizes on the fact that relaying is only required when direct transmission suffers deep fading. We calculate the packet error rate for the proposed efficient incremental relaying (EIR) scheme with both amplify and forward and decode and forward relaying. We compare the performance of the EIR scheme with the threshold-based incremental relaying (TIR) scheme. It is shown that the efficiency of the TIR scheme is better for lower values of the threshold. However, the efficiency of the TIR scheme for higher values of threshold is outperformed by the EIR. In addition, three new threshold-based adaptive EIR are devised to further improve the efficiency of the EIR scheme. We calculate the packet error rate and the efficiency of these new schemes to provide the analytical insight. © 2014 IEEE.

  17. Multifocal ERG wavelet packet decomposition applied to glaucoma diagnosis

    Directory of Open Access Journals (Sweden)

    Rodríguez-Ascariz José M

    2011-05-01

    Full Text Available Abstract Background Glaucoma is the second-leading cause of blindness worldwide and early diagnosis is essential to its treatment. Current clinical methods based on multifocal electroretinography (mfERG essentially involve measurement of amplitudes and latencies and assume standard signal morphology. This paper presents a new method based on wavelet packet analysis of global-flash multifocal electroretinogram signals. Methods This study comprised twenty-five patients diagnosed with OAG and twenty-five control subjects. Their mfERG recordings data were used to develop the algorithm method based on wavelet packet analysis. By reconstructing the third wavelet packet contained in the fourth decomposition level (ADAA4 of the mfERG recording, it is possible to obtain a signal from which to extract a marker in the 60-80 ms time interval. Results The marker found comprises oscillatory potentials with a negative-slope basal line in the case of glaucomatous recordings and a positive-slope basal line in the case of normal signals. Application of the optimal threshold calculated in the validation cases showed that the technique proposed achieved a sensitivity of 0.81 and validation specificity of 0.73. Conclusions This new method based on mfERG analysis may be reliable enough to detect functional deficits that are not apparent using current automated perimetry tests. As new stimulation and analysis protocols develop, mfERG has the potential to become a useful tool in early detection of glaucoma-related functional deficits.

  18. Geometrical aspects in optical wave-packet dynamics.

    Science.gov (United States)

    Onoda, Masaru; Murakami, Shuichi; Nagaosa, Naoto

    2006-12-01

    We construct a semiclassical theory for propagation of an optical wave packet in a nonconducting medium with a periodic structure of dielectric permittivity and magnetic permeability, i.e., a nonconducting photonic crystal. We employ a quantum-mechanical formalism in order to clarify its link to those of electronic systems. It involves the geometrical phase, i.e., Berry's phase, in a natural way, and describes an interplay between orbital motion and internal rotation. Based on the above theory, we discuss the geometrical aspects of the optical Hall effect. We also consider a reduction of the theory to a system without periodic structure and apply it to the transverse shift of an optical beam at an interface reflection or refraction. For a generic incident beam with an arbitrary polarization, an identical result for the transverse shift of each reflected or transmitted beam is given by the following different approaches: (i) analytic evaluation of wave-packet dynamics, (ii) total angular momentum (TAM) conservation for individual photons, and (iii) numerical simulation of wave-packet dynamics. It is consistent with a result by classical electrodynamics. This means that the TAM conservation for individual photons is already taken into account in wave optics, i.e., classical electrodynamics. Finally, we show an application of our theory to a two-dimensional photonic crystal, and propose an optimal design for the enhancement of the optical Hall effect in photonic crystals.

  19. Runge-Lenz wave packet in multichannel Stark photoionization

    International Nuclear Information System (INIS)

    Texier, F.

    2005-01-01

    In a previous slow photoionization experiment, modulations of ionization rings were manifested for Xe in a constant electric field. The present quantum calculation reveals that the modulation is an effect of the multichannel core scattering and of tunneling waves through the Coulomb-Stark potential barrier: the barrier reduces the number of oscillations that is observed relatively to the number of oscillations of the short range wave functions, and the nonhydrogenic core phase shifts modify the position of the ionization rings. We find a hidden difference, in the ionization process, for two close values of the energy depending on the resonance with the barrier. The ionization intensity is interpreted as a Runge-Lenz wave packet; thus, we can relate the quantum modulation to the classical Coulomb-Stark trajectories. The Runge-Lenz wave packet differs from a usual temporal wave packet because its components are eigenstates of the Runge-Lenz vector z projection and its evolution is not temporal but spatial

  20. On Delay and Security in Network Coding

    Science.gov (United States)

    Dikaliotis, Theodoros K.

    2013-01-01

    In this thesis, delay and security issues in network coding are considered. First, we study the delay incurred in the transmission of a fixed number of packets through acyclic networks comprised of erasure links. The two transmission schemes studied are routing with hop-by-hop retransmissions, where every node in the network simply stores and…

  1. Languages for Software-Defined Networks

    Science.gov (United States)

    2013-02-01

    switches, firewalls, and middleboxes) with closed and proprietary configuration inter- faces. Software - Defined Networks ( SDN ) are poised to change...how- ever, have seen growing interest in software - defined networks ( SDNs ), in which a logically-centralized controller manages the packet-processing...switches, firewalls, and middleboxes) with closed and proprietary configuration interfaces. Software - Defined Networks ( SDN ) are poised to change this

  2. Improved routing strategies for data traffic in scale-free networks

    International Nuclear Information System (INIS)

    Wu, Zhi-Xi; Peng, Gang; Wong, Wing-Ming; Yeung, Kai-Hau

    2008-01-01

    We study the information packet routing process in scale-free networks by mimicking Internet traffic delivery. We incorporate both the global shortest paths information and local degree information of the network in the dynamic process, via two tunable parameters, α and β, to guide the packet routing. We measure the performance of the routing method by both the average transit times of packets and the critical packet generation rate (above which packet aggregation occurs in the network). We found that the routing strategies which integrate ingredients of both global and local topological information of the underlying networks perform much better than the traditional shortest path routing protocol taking into account the global topological information only. Moreover, by doing comparative studies with some related works, we found that the performance of our proposed method shows universal efficiency characteristic against the amount of traffic

  3. Quality of service on Linux for the Atlas TDAQ event building network

    International Nuclear Information System (INIS)

    Yasu, Y.; Manabe, A.; Fujii, H.; Watase, Y.; Nagasaka, Y.; Hasegawa, Y.; Shimojima, M.; Nomachi, M.

    2001-01-01

    Congestion control for packets sent on a network is important for DAQ systems that contain an event builder using switching network technologies. Quality of Service (QoS) is a technique for congestion control. Recent Linux releases provide QoS in the kernel to manage network traffic. The authors have analyzed the packet-loss and packet distribution for the event builder prototype of the Atlas TDAQ system. The authors used PC/Linux with Gigabit Ethernet network as the testbed. The results showed that QoS using CBQ and TBF eliminated packet loss on UDP/IP transfer while the UDP/IP transfer in best effort made lots of packet loss. The result also showed that the QoS overhead was small. The authors concluded that QoS on Linux performed efficiently in TCP/IP and UDP/IP and will have an important role of the Atlas TDAQ system

  4. Network architecture in a converged optical + IP network

    Science.gov (United States)

    Wakim, Walid; Zottmann, Harald

    2012-01-01

    As demands on Provider Networks continue to grow at exponential rates, providers are forced to evaluate how to continue to grow the network while increasing service velocity, enhancing resiliency while decreasing the total cost of ownership (TCO). The bandwidth growth that networks are experiencing is in the form packet based multimedia services such as video, video conferencing, gaming, etc... mixed with Over the Top (OTT) content providers such as Netflix, and the customer's expectations that best effort is not enough you end up with a situation that forces the provider to analyze how to gain more out of the network with less cost. In this paper we will discuss changes in the network that are driving us to a tighter integration between packet and optical layers and how to improve on today's multi - layer inefficiencies to drive down network TCO and provide for a fully integrated and dynamic network that will decrease time to revenue.

  5. Sampled-Data Consensus of Linear Multi-agent Systems With Packet Losses.

    Science.gov (United States)

    Zhang, Wenbing; Tang, Yang; Huang, Tingwen; Kurths, Jurgen

    In this paper, the consensus problem is studied for a class of multi-agent systems with sampled data and packet losses, where random and deterministic packet losses are considered, respectively. For random packet losses, a Bernoulli-distributed white sequence is used to describe packet dropouts among agents in a stochastic way. For deterministic packet losses, a switched system with stable and unstable subsystems is employed to model packet dropouts in a deterministic way. The purpose of this paper is to derive consensus criteria, such that linear multi-agent systems with sampled-data and packet losses can reach consensus. By means of the Lyapunov function approach and the decomposition method, the design problem of a distributed controller is solved in terms of convex optimization. The interplay among the allowable bound of the sampling interval, the probability of random packet losses, and the rate of deterministic packet losses are explicitly derived to characterize consensus conditions. The obtained criteria are closely related to the maximum eigenvalue of the Laplacian matrix versus the second minimum eigenvalue of the Laplacian matrix, which reveals the intrinsic effect of communication topologies on consensus performance. Finally, simulations are given to show the effectiveness of the proposed results.In this paper, the consensus problem is studied for a class of multi-agent systems with sampled data and packet losses, where random and deterministic packet losses are considered, respectively. For random packet losses, a Bernoulli-distributed white sequence is used to describe packet dropouts among agents in a stochastic way. For deterministic packet losses, a switched system with stable and unstable subsystems is employed to model packet dropouts in a deterministic way. The purpose of this paper is to derive consensus criteria, such that linear multi-agent systems with sampled-data and packet losses can reach consensus. By means of the Lyapunov function

  6. Computer-communication networks

    CERN Document Server

    Meditch, James S

    1983-01-01

    Computer- Communication Networks presents a collection of articles the focus of which is on the field of modeling, analysis, design, and performance optimization. It discusses the problem of modeling the performance of local area networks under file transfer. It addresses the design of multi-hop, mobile-user radio networks. Some of the topics covered in the book are the distributed packet switching queuing network design, some investigations on communication switching techniques in computer networks and the minimum hop flow assignment and routing subject to an average message delay constraint

  7. A Cluster- Based Secure Active Network Environment

    Institute of Scientific and Technical Information of China (English)

    CHEN Xiao-lin; ZHOU Jing-yang; DAI Han; LU Sang-lu; CHEN Gui-hai

    2005-01-01

    We introduce a cluster-based secure active network environment (CSANE) which separates the processing of IP packets from that of active packets in active routers. In this environment, the active code authorized or trusted by privileged users is executed in the secure execution environment (EE) of the active router, while others are executed in the secure EE of the nodes in the distributed shared memory (DSM) cluster. With the supports of a multi-process Java virtual machine and KeyNote, untrusted active packets are controlled to securely consume resource. The DSM consistency management makes that active packets can be parallelly processed in the DSM cluster as if they were processed one by one in ANTS (Active Network Transport System). We demonstrate that CSANE has good security and scalability, but imposing little changes on traditional routers.

  8. Intrusion Detection System Using Deep Neural Network for In-Vehicle Network Security.

    Directory of Open Access Journals (Sweden)

    Min-Joo Kang

    Full Text Available A novel intrusion detection system (IDS using a deep neural network (DNN is proposed to enhance the security of in-vehicular network. The parameters building the DNN structure are trained with probability-based feature vectors that are extracted from the in-vehicular network packets. For a given packet, the DNN provides the probability of each class discriminating normal and attack packets, and, thus the sensor can identify any malicious attack to the vehicle. As compared to the traditional artificial neural network applied to the IDS, the proposed technique adopts recent advances in deep learning studies such as initializing the parameters through the unsupervised pre-training of deep belief networks (DBN, therefore improving the detection accuracy. It is demonstrated with experimental results that the proposed technique can provide a real-time response to the attack with a significantly improved detection ratio in controller area network (CAN bus.

  9. Intrusion Detection System Using Deep Neural Network for In-Vehicle Network Security.

    Science.gov (United States)

    Kang, Min-Joo; Kang, Je-Won

    2016-01-01

    A novel intrusion detection system (IDS) using a deep neural network (DNN) is proposed to enhance the security of in-vehicular network. The parameters building the DNN structure are trained with probability-based feature vectors that are extracted from the in-vehicular network packets. For a given packet, the DNN provides the probability of each class discriminating normal and attack packets, and, thus the sensor can identify any malicious attack to the vehicle. As compared to the traditional artificial neural network applied to the IDS, the proposed technique adopts recent advances in deep learning studies such as initializing the parameters through the unsupervised pre-training of deep belief networks (DBN), therefore improving the detection accuracy. It is demonstrated with experimental results that the proposed technique can provide a real-time response to the attack with a significantly improved detection ratio in controller area network (CAN) bus.

  10. Network Function Virtualisation

    OpenAIRE

    Aakarshan Singh; Kamal Grover; Palak Bansal; Taranveer Singh Seekhon

    2017-01-01

    This paper is written to give basic knowledge of Network function virtualisation in network system. In this paper the work on NFV done till now has been collaborated. It describes how the challenges faced by industry lead to NFV and what is meaning of NFV and NFV architecture model. It also explains NFV Infrastructure is managed and the forwarding path on which packets traverse in NFV. A relationship of NFV with SDN and current research ongoing on NFV policies is discussed.

  11. Applying a rateless code in content delivery networks

    Science.gov (United States)

    Suherman; Zarlis, Muhammad; Parulian Sitorus, Sahat; Al-Akaidi, Marwan

    2017-09-01

    Content delivery network (CDN) allows internet providers to locate their services, to map their coverage into networks without necessarily to own them. CDN is part of the current internet infrastructures, supporting multi server applications especially social media. Various works have been proposed to improve CDN performances. Since accesses on social media servers tend to be short but frequent, providing redundant to the transmitted packets to ensure lost packets not degrade the information integrity may improve service performances. This paper examines the implementation of rateless code in the CDN infrastructure. The NS-2 evaluations show that rateless code is able to reduce packet loss up to 50%.

  12. Collaborative Multi-Layer Network Coding in Hybrid Cellular Cognitive Radio Networks

    KAUST Repository

    Moubayed, Abdallah J.

    2015-05-01

    In this paper, as an extension to [1], we propose a prioritized multi-layer network coding scheme for collaborative packet recovery in hybrid (interweave and underlay) cellular cognitive radio networks. This scheme allows the uncoordinated collaboration between the collocated primary and cognitive radio base-stations in order to minimize their own as well as each other\\'s packet recovery overheads, thus by improving their throughput. The proposed scheme ensures that each network\\'s performance is not degraded by its help to the other network. Moreover, it guarantees that the primary network\\'s interference threshold is not violated in the same and adjacent cells. Yet, the scheme allows the reduction of the recovery overhead in the collocated primary and cognitive radio networks. The reduction in the cognitive radio network is further amplified due to the perfect detection of spectrum holes which allows the cognitive radio base station to transmit at higher power without fear of violating the interference threshold of the primary network. For the secondary network, simulation results show reductions of 20% and 34% in the packet recovery overhead, compared to the non-collaborative scheme, for low and high probabilities of primary packet arrivals, respectively. For the primary network, this reduction was found to be 12%. © 2015 IEEE.

  13. Nonspreading Wave Packets for Rydberg Electrons in Rotating Molecules with Electric Dipole Moments

    International Nuclear Information System (INIS)

    Bialynicki-Birula, I.; Bialynicka-Birula, Z.

    1996-01-01

    Nonspreading wave packets for Rydberg electrons are predicted in rotating molecules with electric dipole moments. We have named them the Trojan wave packets since their stability is due to the same mechanism that governs the motion of the Trojan asteroids in the Sun-Jupiter system. Unlike all previously predicted Trojan wave packets in atoms, molecular Trojan states do not require external fields for their existence

  14. Principles of broadband switching and networking

    CERN Document Server

    Liew, Soung C

    2010-01-01

    An authoritative introduction to the roles of switching and transmission in broadband integrated services networks Principles of Broadband Switching and Networking explains the design and analysis of switch architectures suitable for broadband integrated services networks, emphasizing packet-switched interconnection networks with distributed routing algorithms. The text examines the mathematical properties of these networks, rather than specific implementation technologies. Although the pedagogical explanations in this book are in the context of switches, many of the fundamenta

  15. Wave packet formulation of the boomerang model for resonant electron--molecule scattering

    International Nuclear Information System (INIS)

    McCurdy, C.W.; Turner, J.L.

    1983-01-01

    A time-dependent formulation of the boomerang model for resonant electron--molecule scattering is presented in terms of a wave packet propagating on the complex potential surface of the metastable anion. The results of calculations using efficient semiclassical techniques for propagating the wave packet are found to be in excellent agreement with full quantum-mechanical calculations of vibrational excitation cross sections in e - --N 2 scattering. The application of the wave packet formulation as a computational and conceptual approach to the problem of resonant collisions with polyatomic molecules is discussed in the light of recent wave packet calculations on polyatomic photodissociation and Raman spectra

  16. A Time-Frequency Auditory Model Using Wavelet Packets

    DEFF Research Database (Denmark)

    Agerkvist, Finn

    1996-01-01

    A time-frequency auditory model is presented. The model uses the wavelet packet analysis as the preprocessor. The auditory filters are modelled by the rounded exponential filters, and the excitation is smoothed by a window function. By comparing time-frequency excitation patterns it is shown...... that the change in the time-frequency excitation pattern introduced when a test tone at masked threshold is added to the masker is approximately equal to 7 dB for all types of maskers. The classic detection ratio therefore overrates the detection efficiency of the auditory system....

  17. Theoretical prediction of a rotating magnon wave packet in ferromagnets.

    Science.gov (United States)

    Matsumoto, Ryo; Murakami, Shuichi

    2011-05-13

    We theoretically show that the magnon wave packet has a rotational motion in two ways: a self-rotation and a motion along the boundary of the sample (edge current). They are similar to the cyclotron motion of electrons, but unlike electrons the magnons have no charge and the rotation is not due to the Lorentz force. These rotational motions are caused by the Berry phase in momentum space from the magnon band structure. Furthermore, the rotational motion of the magnon gives an additional correction term to the magnon Hall effect. We also discuss the Berry curvature effect in the classical limit of long-wavelength magnetostatic spin waves having macroscopic coherence length.

  18. Memory of AMR coded speech distorted by packet loss

    OpenAIRE

    Nykänen, Arne; Lindegren, David; Wruck, Louisa; Ljung, Robert; Odelius, Johan; Möller, Sebastian

    2014-01-01

    Previous studies have shown that free recall of spoken word lists is impaired if the speech is presented in background noise, even if the signal-to-noise ratio is kept at a level allowing full word identification. The objective of this study was to examine recall rates for word lists presented in noise and word lists coded by an AMR (Adaptive Multi Rate) telephone codec distorted by packet loss. Twenty subjects performed a word recall test. Word lists consisting of ten words were played to th...

  19. Riemann zeta function from wave-packet dynamics

    DEFF Research Database (Denmark)

    Mack, R.; Dahl, Jens Peder; Moya-Cessa, H.

    2010-01-01

    We show that the time evolution of a thermal phase state of an anharmonic oscillator with logarithmic energy spectrum is intimately connected to the generalized Riemann zeta function zeta(s, a). Indeed, the autocorrelation function at a time t is determined by zeta (sigma + i tau, a), where sigma...... index of JWKB. We compare and contrast exact and approximate eigenvalues of purely logarithmic potentials. Moreover, we use a numerical method to find a potential which leads to exact logarithmic eigenvalues. We discuss possible realizations of Riemann zeta wave-packet dynamics using cold atoms...

  20. Unified broadcast in sensor networks

    DEFF Research Database (Denmark)

    Hansen, Morten Tranberg; Jurdak, Raja; Kusy, Branislav

    2011-01-01

    of the network stack. UB is implemented as a transparent layer between the link and network layers, where it delays, schedules, and combines broadcasts from upper layer protocols before transmission on the wireless channel. Our empirical results in simulation and on a testbed show that UB can decrease...... the overall packet transmissions in the network by more than 60%, corresponding to more than 40% energy savings, without requiring new interfaces or affecting the correctness of the upper layer protocols....

  1. Undersea Communication Network Self-Localization during the Unet󈧌 Seatrial

    Science.gov (United States)

    2010-06-01

    Multiple Access Collision Avoidance ( MACA ) suitable for underwater networks [6]. Control frames are short 9-byte utility packets which are...Proceedings of the MILCOM’08 Conference, San Diego, CA, USA, November 2008. [6] P. Karn, MACA --a new channel access method for packet radio, in ARRL/CRRL

  2. Using Self-management for Establishing Light Paths in Optical Networks: an Overview

    NARCIS (Netherlands)

    Fioreze, Tiago; Pras, Aiko

    2006-01-01

    Current optical networks are generally composed of multi-service optical switches, which enable forwarding of data at multiple levels. Huge flows at the packet-level (IP-level) may be moved to the optical-level, which is faster than the packet-level. Such move could be beneficial since congested IP

  3. TMAC: Timestamp-Ordered MAC for CSMA/CA Wireless Mesh Networks

    KAUST Repository

    Nawab, Faisal Saud Yousef; Jamshaid, Kamran; Shihada, Basem; Ho, Pin-Han

    2011-01-01

    We propose TMAC, a timestamp-ordered MAC protocol for Wireless Mesh Networks (WMNs). TMAC extends CSMA/CA by scheduling data packets based on their age. Prior to transmitting a data packet, a transmitter broadcasts a request control message appended

  4. Asymmetric Propagation Delay-Aware TDMA MAC Protocol for Mobile Underwater Acoustic Sensor Networks

    Directory of Open Access Journals (Sweden)

    A-Ra Cho

    2018-06-01

    Full Text Available The propagation delay in mobile underwater acoustic sensor network (MUASN is asymmetric because of its low sound propagation speed, and this asymmetry grows with the increase in packet travel time, which damages the collision avoidance mechanism of the spatial reuse medium access control (MAC protocols for MUASN. We propose an asymmetric propagation delay-aware time division multiple access (APD-TDMA for a MUASN in which periodic data packet transmission is required for a sink node (SN. Collisions at the SN are avoided by deferring data packet transmission after reception of a beacon packet from the SN, and data packets are arrived at the SN in a packet-train manner. The time-offset, which is the time for a node to wait before the transmission of a data packet after reception of a beacon packet, is determined by estimating the propagation delay over two consecutive cycles such that the idle interval at the SN is minimized, and this time-offset is announced by the beacon packet. Simulation results demonstrate that the APD-TDMA improves the channel access delay and the channel utilization by approximately 20% and 30%, respectively, compared with those of the block time bounded TDMA under the given network conditions.

  5. Security for multi-hop wireless networks

    CERN Document Server

    Mahmoud, Mohamed M E A

    2014-01-01

    This Springer Brief discusses efficient security protocols and schemes for multi-hop wireless networks. It presents an overview of security requirements for these networks, explores challenges in securing networks and presents system models. The authors introduce mechanisms to reduce the overhead and identify malicious nodes that drop packets intentionally. Also included is a new, efficient cooperation incentive scheme to stimulate the selfish nodes to relay information packets and enforce fairness. Many examples are provided, along with predictions for future directions of the field. Security

  6. Introduction to Network Simulator NS2

    CERN Document Server

    Issariyakul, Teerawat

    2012-01-01

    "Introduction to Network Simulator NS2" is a primer providing materials for NS2 beginners, whether students, professors, or researchers for understanding the architecture of Network Simulator 2 (NS2) and for incorporating simulation modules into NS2. The authors discuss the simulation architecture and the key components of NS2 including simulation-related objects, network objects, packet-related objects, and helper objects. The NS2 modules included within are nodes, links, SimpleLink objects, packets, agents, and applications. Further, the book covers three helper modules: timers, ra

  7. Network Coded Cooperation Over Time-Varying Channels

    DEFF Research Database (Denmark)

    Khamfroush, Hana; Roetter, Daniel Enrique Lucani; Barros, João

    2014-01-01

    transmissions, e.g., in terms of the rate of packet transmission or the energy consumption. A comprehensive analysis of the MDP solution is carried out under different network conditions to extract optimal rules of packet transmission. Inspired by the extracted rules, we propose two near-optimal heuristics......In this paper, we investigate the optimal design of cooperative network-coded strategies for a three-node wireless network with time-varying, half-duplex erasure channels. To this end, we formulate the problem of minimizing the total cost of transmitting M packets from source to two receivers...... as a Markov Decision Process (MDP). The actions of the MDP model include the source and the type of transmission to be used in a given time slot given perfect knowledge of the system state. The cost of packet transmission is defined such that it can incorporate the difference between broadcast and unicast...

  8. On the Update Problems for Software Defined Networks

    Directory of Open Access Journals (Sweden)

    V. A. Zakharov

    2014-01-01

    Full Text Available The designing of network update algorithms is urgent for the development of SDN control software. A particular case of Network Update Problem is that of restoring seamlessly a given network configuration after some packet forwarding rules have been disabled (say, at the expiry of their time-outs. We study this problem in the framework of a formal model of SDN, develop correct and safe network recovering algorithms, and show that in general case there is no way to restore network configuration seamlessly without referring to priorities of packet forwarding rules.

  9. Heralded wave packet manipulation and storage of a frequency-converted pair photon at telecom wavelength

    Science.gov (United States)

    Kroh, Tim; Ahlrichs, Andreas; Sprenger, Benjamin; Benson, Oliver

    2017-09-01

    Future quantum networks require a hybrid platform of dissimilar quantum systems. Within the platform, joint quantum states have to be mediated either by single photons, photon pairs or entangled photon pairs. The photon wavelength has to lie within the telecommunication band to enable long-distance fibre transmission. In addition, the temporal shape of the photons needs to be tailored to efficiently match the involved quantum systems. Altogether, this requires the efficient coherent wavelength-conversion of arbitrarily shaped single-photon wave packets. Here, we demonstrate the heralded temporal filtering of single photons as well as the synchronisation of state manipulation and detection as key elements in a typical experiment, besides of delaying a photon in a long fibre. All three are realised by utilising commercial telecommunication fibre-optical components which will permit the transition of quantum networks from the lab to real-world applications. The combination of these renders a temporally filtering single-photon storage in a fast switchable fibre loop possible.

  10. Reliable Wireless Broadcast with Linear Network Coding for Multipoint-to-Multipoint Real-Time Communications

    Science.gov (United States)

    Kondo, Yoshihisa; Yomo, Hiroyuki; Yamaguchi, Shinji; Davis, Peter; Miura, Ryu; Obana, Sadao; Sampei, Seiichi

    This paper proposes multipoint-to-multipoint (MPtoMP) real-time broadcast transmission using network coding for ad-hoc networks like video game networks. We aim to achieve highly reliable MPtoMP broadcasting using IEEE 802.11 media access control (MAC) that does not include a retransmission mechanism. When each node detects packets from the other nodes in a sequence, the correctly detected packets are network-encoded, and the encoded packet is broadcasted in the next sequence as a piggy-back for its native packet. To prevent increase of overhead in each packet due to piggy-back packet transmission, network coding vector for each node is exchanged between all nodes in the negotiation phase. Each user keeps using the same coding vector generated in the negotiation phase, and only coding information that represents which user signal is included in the network coding process is transmitted along with the piggy-back packet. Our simulation results show that the proposed method can provide higher reliability than other schemes using multi point relay (MPR) or redundant transmissions such as forward error correction (FEC). We also implement the proposed method in a wireless testbed, and show that the proposed method achieves high reliability in a real-world environment with a practical degree of complexity when installed on current wireless devices.

  11. Serial Network Flow Monitor

    Science.gov (United States)

    Robinson, Julie A.; Tate-Brown, Judy M.

    2009-01-01

    Using a commercial software CD and minimal up-mass, SNFM monitors the Payload local area network (LAN) to analyze and troubleshoot LAN data traffic. Validating LAN traffic models may allow for faster and more reliable computer networks to sustain systems and science on future space missions. Research Summary: This experiment studies the function of the computer network onboard the ISS. On-orbit packet statistics are captured and used to validate ground based medium rate data link models and enhance the way that the local area network (LAN) is monitored. This information will allow monitoring and improvement in the data transfer capabilities of on-orbit computer networks. The Serial Network Flow Monitor (SNFM) experiment attempts to characterize the network equivalent of traffic jams on board ISS. The SNFM team is able to specifically target historical problem areas including the SAMS (Space Acceleration Measurement System) communication issues, data transmissions from the ISS to the ground teams, and multiple users on the network at the same time. By looking at how various users interact with each other on the network, conflicts can be identified and work can begin on solutions. SNFM is comprised of a commercial off the shelf software package that monitors packet traffic through the payload Ethernet LANs (local area networks) on board ISS.

  12. Networking

    OpenAIRE

    Rauno Lindholm, Daniel; Boisen Devantier, Lykke; Nyborg, Karoline Lykke; Høgsbro, Andreas; Fries, de; Skovlund, Louise

    2016-01-01

    The purpose of this project was to examine what influencing factor that has had an impact on the presumed increasement of the use of networking among academics on the labour market and how it is expressed. On the basis of the influence from globalization on the labour market it can be concluded that the globalization has transformed the labour market into a market based on the organization of networks. In this new organization there is a greater emphasis on employees having social qualificati...

  13. Collaborative Multi-Layer Network Coding For Hybrid Cellular Cognitive Radio Networks

    KAUST Repository

    Moubayed, Abdallah J.

    2014-05-01

    In this thesis, as an extension to [1], we propose a prioritized multi-layer network coding scheme for collaborative packet recovery in hybrid (interweave and underlay) cellular cognitive radio networks. This scheme allows the uncoordinated collaboration between the collocated primary and cognitive radio base-stations in order to minimize their own as well as each other’s packet recovery overheads, thus by improving their throughput. The proposed scheme ensures that each network’s performance is not degraded by its help to the other network. Moreover, it guarantees that the primary network’s interference threshold is not violated in the same and adjacent cells. Yet, the scheme allows the reduction of the recovery overhead in the collocated primary and cognitive radio networks. The reduction in the cognitive radio network is further amplified due to the perfect detection of spectrum holes which allows the cognitive radio base station to transmit at higher power without fear of violating the interference threshold of the primary network. For the secondary network, simulation results show reductions of 20% and 34% in the packet recovery overhead, compared to the non-collaborative scheme, for low and high probabilities of primary packet arrivals, respectively. For the primary network, this reduction was found to be 12%. Furthermore, with the use of fractional cooperation, the average recovery overhead is further reduced by around 5% for the primary network and around 10% for the secondary network when a high fractional cooperation probability is used.

  14. Routing strategies in traffic network and phase transition in network ...

    Indian Academy of Sciences (India)

    The dynamics of information traffic over scale-free networks has been investigated systematically. A series of routing strategies of data packets have been proposed, including the local routing strategy, the next-nearest-neighbour routing strategy, and the mixed routing strategy based on local static and dynamic information.

  15. Asynchronous control for networked systems

    CERN Document Server

    Rubio, Francisco; Bencomo, Sebastián

    2015-01-01

    This book sheds light on networked control systems; it describes different techniques for asynchronous control, moving away from the periodic actions of classical control, replacing them with state-based decisions and reducing the frequency with which communication between subsystems is required. The text focuses specially on event-based control. Split into two parts, Asynchronous Control for Networked Systems begins by addressing the problems of single-loop networked control systems, laying out various solutions which include two alternative model-based control schemes (anticipatory and predictive) and the use of H2/H∞ robust control to deal with network delays and packet losses. Results on self-triggering and send-on-delta sampling are presented to reduce the need for feedback in the loop. In Part II, the authors present solutions for distributed estimation and control. They deal first with reliable networks and then extend their results to scenarios in which delays and packet losses may occur. The novel ...

  16. Energy-Efficient Cluster Based Routing Protocol in Mobile Ad Hoc Networks Using Network Coding

    OpenAIRE

    Srinivas Kanakala; Venugopal Reddy Ananthula; Prashanthi Vempaty

    2014-01-01

    In mobile ad hoc networks, all nodes are energy constrained. In such situations, it is important to reduce energy consumption. In this paper, we consider the issues of energy efficient communication in MANETs using network coding. Network coding is an effective method to improve the performance of wireless networks. COPE protocol implements network coding concept to reduce number of transmissions by mixing the packets at intermediate nodes. We incorporate COPE into cluster based routing proto...

  17. Hidden Markov Model-based Packet Loss Concealment for Voice over IP

    DEFF Research Database (Denmark)

    Rødbro, Christoffer A.; Murthi, Manohar N.; Andersen, Søren Vang

    2006-01-01

    As voice over IP proliferates, packet loss concealment (PLC) at the receiver has emerged as an important factor in determining voice quality of service. Through the use of heuristic variations of signal and parameter repetition and overlap-add interpolation to handle packet loss, conventional PLC...

  18. Personal Skills. Facilitator's Skill Packets 1-7. Social Skills Training.

    Science.gov (United States)

    Model Classrooms, Bellevue, WA.

    This document contains the following seven facilitators' skill packets on personal skills: (1) personal hygiene; (2) personal appearance; (3) locker hygiene; (4) dorm cleanliness; (5) punctuality and attendance; (6) responding to supervision; and (7) teamwork. Each packet contains the following sections: definition of personal skills; objective;…

  19. A multi-function IEC 61850 packet generator based on FPGA

    International Nuclear Information System (INIS)

    Wei, Wei; Li, Hong-bin; Cheng, Han-miao

    2016-01-01

    An IEC 61850 packet generator is used to produce IEC 61850-9-2 packets by simulating the merging unit and testing the IEC 61850 digital device. While the existing IEC packet generator can produce ideal digital without any noise, it does not take into account the fact that the merging unit output signal packets will be inevitably superimposed with noise. Since the International Electrical Commission standard of the electronic current transformer specifies the minimum output signal-to-noise ratio of the merging unit to be 30 dB, and the signal superimposed with noise will influence the operation performance of the digital device, it is necessary to design a multi-function IEC 61850-9-2 packet generator for a digital device test. Therefore, in this paper, a multi-function IEC 61850 packet generator has been developed, which not only can output various IEC 61850-9-2 packets, but also can add white Gaussian noise to the signal for digital device testing. By testing three digital electricity meters from different manufacturers, we showed that the error of the digital electricity meter is significantly larger when the signal packet is superimposed with noise. Also when the signal-to-noise ration is 30 dB, the error of one of the meters exceeds the allowed range of the accuracy class. This indicates that the noise testing and the noise setting function of the system has an important role in the testing of a digital device. (paper)

  20. 160 Gb/s all-optical packet switching field experiment

    DEFF Research Database (Denmark)

    Dorren, H.J.S.; Herrera, J.; Raz, O.

    2007-01-01

    We discus an all-optical packet switching experiment over 110 km of field installed optical fiber. The switching node is controlled by solely photonic control circuits.......We discus an all-optical packet switching experiment over 110 km of field installed optical fiber. The switching node is controlled by solely photonic control circuits....

  1. The United States History = Lich Su Hoa Ky. [34 Self-Learning Packets for Vietnamese Students.

    Science.gov (United States)

    Nhi, Do Dien; And Others

    Designed primarily for Indochinese students in grades 9-12, 34 United States history self-learning packets are presented in eight sections. The publication could be used by mainstream teachers who have a number of limited English proficient (LEP) Vietnamese students in their classes or by parents to tutor their children. The packets were adapted…

  2. Controllable thousand-port low-latency optical packet switch architecture for short link applications

    NARCIS (Netherlands)

    Di Lucente, S.; Nazarathy, J.; Raz, O.; Calabretta, N.; Dorren, H.J.S.; Bienstman, P.; Morthier, G.; Roelkens, G.; et al., xx

    2011-01-01

    The implementation of a low-latency optical packet switch architecture that is controllable while scaling to over thousand ports is investigated in this paper. Optical packet switches with thousand of input/output ports are promising devices to improve the performance of short link applications in

  3. Scalable In-Band Optical Notch-Filter Labeling for Ultrahigh Bit Rate Optical Packet Switching

    DEFF Research Database (Denmark)

    Medhin, Ashenafi Kiros; Galili, Michael; Oxenløwe, Leif Katsuo

    2014-01-01

    We propose a scalable in-band optical notch-filter labeling scheme for optical packet switching of high-bit-rate data packets. A detailed characterization of the notch-filter labeling scheme and its effect on the quality of the data packet is carried out in simulation and verified by experimental...... demonstrations. The scheme is able to generate more than 91 different labels that can be applied to 640-Gb/s optical time division multiplexed packets causing an eye opening penalty of $1.2-dB. Experimental demonstration shows that up to 256 packets can be uniquely labeled by employing up to eight notch filters...... with only 0.9-dB power penalty to achieve BER of 1E-9. Using the proposed labeling scheme, optical packet switching of 640 Gb/s data packets is experimentally demonstrated in which two data packets are labeled by making none and one spectral hole using a notch filter and are switched using a LiNbO$_3...

  4. In the Public Interest: Law, Government, and Media. Maryland Women's History Resource Packet--1986.

    Science.gov (United States)

    Maryland State Commission for Women, Baltimore.

    Designed to be used for National Women's History Week (March 2-8), this 1986 Maryland women's history resource packet centers around Maryland women who have made significant volunteer and career contributions in the areas of government, law, and the public interest media. The packet begins with suggested student activity lists and activity sheets…

  5. Easements in Texas. Teachers Instructional Packet, TIP No. 5, Spring 1985.

    Science.gov (United States)

    Texas A and M Univ., College Station. Texas Real Estate Research Center.

    Part of a series of classroom aids designed for real estate instructors, this instructional packet was developed to help real estate students understand public and private easements, which most commonly entail the right of a person (or the public) to use the land of another in a certain manner. Following an evaluation form for the packet, a…

  6. Ripples in Communication : Reconfigurable and Adaptive Wireless Communication Systems based on Wavelet Packet Modulators

    NARCIS (Netherlands)

    Lakshmanan, M.K.

    2011-01-01

    Wavelet Packet Modulation (WPM) is a multi-carrier transmission technique that uses orthogonal wavelet packet bases to combine a collection of information bits into a single composite signal. This system can be considered as a viable alternative, for wide-band communication, to the popular

  7. Aeroacoustic directivity via wave-packet analysis of mean or base flows

    Science.gov (United States)

    Edstrand, Adam; Schmid, Peter; Cattafesta, Louis

    2017-11-01

    Noise pollution is an ever-increasing problem in society, and knowledge of the directivity patterns of the sound radiation is required for prediction and control. Directivity is frequently determined through costly numerical simulations of the flow field combined with an acoustic analogy. We introduce a new computationally efficient method of finding directivity for a given mean or base flow field using wave-packet analysis (Trefethen, PRSA 2005). Wave-packet analysis approximates the eigenvalue spectrum with spectral accuracy by modeling the eigenfunctions as wave packets. With the wave packets determined, we then follow the method of Obrist (JFM, 2009), which uses Lighthill's acoustic analogy to determine the far-field sound radiation and directivity of wave-packet modes. We apply this method to a canonical jet flow (Gudmundsson and Colonius, JFM 2011) and determine the directivity of potentially unstable wave packets. Furthermore, we generalize the method to consider a three-dimensional flow field of a trailing vortex wake. In summary, we approximate the disturbances as wave packets and extract the directivity from the wave-packet approximation in a fraction of the time of standard aeroacoustic solvers. ONR Grant N00014-15-1-2403.

  8. Reduction in Power Consumption of Packet Counter on VIRTEX-6 FPGA by Frequency Scaling

    DEFF Research Database (Denmark)

    Pandey, Nisha; Pandey, Bishwajeet; Hussain, Dil muhammed Akbar

    2017-01-01

    In Today’s World it is very easy to share the information fast may be within seconds or even may be less. However, the required data is shared so it is the main concern. We share data over web and data is transferred in the form of packets. How these data packets are transmitted is all concept of...

  9. Numerical simulation of the nonlinear dynamics of packets of spiral density waves

    International Nuclear Information System (INIS)

    Korchagin, V.I.

    1987-01-01

    In a numerical experiment, the behavior of nonlinear packets of spiral density waves in a gas disk has been investigated for different initial wave amplitudes. If the amplitude of the density perturbations is small (<5%), the wave packet is drawn toward the center or toward the periphery of the disk in accordance with the linear theory. The behavior of linear packets of waves with wavelength comparable to the disk radius (R/sub d//lambda = 4) exhibits good agreement with the conclusions of the linear theory of tightly wound spiral waves. The dynamics of wave packets with initial density amplitudes 16, 30, 50% demonstrates the nonlinear nature of the behavior. THe behavior is governed by whether or not the nonlinear effects of higher than third order in the wave amplitude play a part. If the wave packet dynamics is determined by the cubic nonlinearity, the results of the numerical experiment are in qualitative and quantitative agreement with the nonlinear theory of short waves, although the characteristic scale of the packet and the wavelength are of the order of the disk radius. In the cases when the nonlinear effects of higher orders in the amplitude play an important part, the behavior of a packet does not differ qualitatively from the behavior predicted by the theory of cubic nonlinearity, but the nonlinear spreading of the packet takes place more rapidly

  10. 78 FR 10263 - Proposed Collection; Comment Request for ADA Accommodations Request Packet

    Science.gov (United States)

    2013-02-13

    ... DEPARTMENT OF THE TREASURY Internal Revenue Service Proposed Collection; Comment Request for ADA... the ADA Accommodations Packet. DATES: Written comments should be received on or before April 15, 2013...: ADA Accommodations Request Packet. OMB Number: 1545-2027. Abstract: Information is collected so that...

  11. A Scheduling Algorithm for Time Bounded Delivery of Packets on the Internet

    NARCIS (Netherlands)

    I. Vaishnavi (Ishan)

    2008-01-01

    htmlabstractThis thesis aims to provide a better scheduling algorithm for Real-Time delivery of packets. A number of emerging applications such as VoIP, Tele-immersive environments, distributed media viewing and distributed gaming require real-time delivery of packets. Currently the scheduling

  12. Message transfer in a communication network

    Indian Academy of Sciences (India)

    Examples of transport processes on networks include the traffic of informa- tion packets [1–4], transport processes on biological networks [5,6], and road traffic. ... for this system. In the case of single message transfer, we study the dependence of average travel times on the hub density, and find that travel times fall off as a.

  13. Understanding the context of network traffic alerts

    NARCIS (Netherlands)

    Cappers, B.C.M.; van Wijk, J.J.; Best, D.M.; Staheli, D.; Prigent, N.; Engle, S.; Harrison, L.

    2016-01-01

    For the protection of critical infrastructures against complex virus attacks, automated network traffic analysis and deep packet inspection are unavoidable. However, even with the use of network intrusion detection systems, the number of alerts is still too large to analyze manually. In addition,

  14. Network Coding Protocols for Data Gathering Applications

    DEFF Research Database (Denmark)

    Nistor, Maricica; Roetter, Daniel Enrique Lucani; Barros, João

    2015-01-01

    Tunable sparse network coding (TSNC) with various sparsity levels of the coded packets and different feedback mechanisms is analysed in the context of data gathering applications in multi-hop networks. The goal is to minimize the completion time, i.e., the total time required to collect all data ...

  15. Network Coding Protocols for Smart Grid Communications

    DEFF Research Database (Denmark)

    Prior, Rui; Roetter, Daniel Enrique Lucani; Phulpin, Yannick

    2014-01-01

    We propose a robust network coding protocol for enhancing the reliability and speed of data gathering in smart grids. At the heart of our protocol lies the idea of tunable sparse network coding, which adopts the transmission of sparsely coded packets at the beginning of the transmission process b...

  16. Comparison of new hybrid FEEMD-MLP, FEEMD-ANFIS, Wavelet Packet-MLP and Wavelet Packet-ANFIS for wind speed predictions

    International Nuclear Information System (INIS)

    Liu, Hui; Tian, Hong-qi; Li, Yan-fei

    2015-01-01

    Highlights: • Four algorithms [EMD/FEEMD/WD/WPD] are proposed for the wind speed decomposition. • Two new hybrid forecasting algorithms [FEEMD-MLP/ANFIS] are presented. • The contributions of the FEEMD/WPD algorithms are both significant. • The MLP has better forecasting performance than the ANFIS in these cases. • All the proposed hybrid algorithms are suitable for the wind speed predictions. - Abstract: The technology of wind speed prediction is important to guarantee the safety of wind power utilization. Compared to the single algorithms, the hybrid ones always have better performance in the wind speed predictions. In this paper, three most important decomposing algorithms [Wavelet Decomposition – WD/Wavelet Packet Decomposition – WPD/Empirical Mode Decomposition – EMD] and a latest decomposing algorithm [Fast Ensemble Empirical Mode Decomposition – FEEMD] are all adopted to realize the wind speed high-precision predictions with two representative networks [MLP Neural Network/ANFIS Neural Network]. Based on the hybrid forecasting framework, two new wind speed forecasting methods [FEEMD-MLP and FEEMD-ANFIS] are proposed. Additionally, a series of performance comparison is provided, which includes EMD-MLP, FEEMD-MLP, EDM-ANFIS, FEEMD-ANFIS, WD-MLP, WD-ANFIS, WPD-MLP and WPD-ANFIS. The aim of the study is to investigate the decomposing and forecasting performance of the different hybrid models. Two experimental results show that: (1) Due to the inclusion of the decomposing algorithms, the hybrid ANN algorithms have better performance than their corresponding single ANN algorithms; (2) the proposed new FEEMD-MLP hybrid model has the best performance in the three-step predictions while the WPD-MLP hybrid model has the best performance in the one-step predictions; (3) among the decomposing algorithms, the FEEMD and WPD have better performance than the EMD and WD, respectively; (4) in the forecasting neural networks, the MLP has better performance

  17. Klasifikasi Paket Jaringan Berbasis Analisis Statistik dan Neural Network

    Directory of Open Access Journals (Sweden)

    Harsono Harsono

    2018-01-01

    Full Text Available Distributed Denial-of-Service (DDoS is one of network attack technique which increased every year, especially in both of intensity and volume. DDoS attacks are still one of the world's major Internet threats and become a major problem of cyber-world security. Research in this paper aims to establish a new approach on network packets classification, which can be a basis for framework development on Distributed Denial-of-Service (DDoS attack detection systems. The proposed approach to solving the problem on network packet classification is by combining statistical data quantification methods with neural network methods. Based on the test, it is found that the average percentage of neural network classification accuracy against network data packet is 92.99%.

  18. IP Traceback through modified Probabilistic Packet Marking algorithm using Chinese Remainder Theorem

    Directory of Open Access Journals (Sweden)

    Y. Bhavani

    2015-06-01

    Full Text Available Probabilistic Packet Marking algorithm suggests a methodology to identify all the participated routers of the attack path by probabilistically marking the packets. In this approach, these marked packets contain partial information regarding the routers of the attack path. At receiver, to get the complete information of every router, it requires more number of marked packets and hence more combinations and more false positives. To overcome this drawback we have presented a novel idea in finding the exact IP address of the routers in the attack path by applying Chinese Remainder Theorem. The result of our implementation reveals that our idea requires less number of marked packets and takes no time in constructing the attack path. The same idea is true even in the case of multiple attackers.

  19. Dynamics of electron wave packet in a disordered chain with delayed nonlinear response

    International Nuclear Information System (INIS)

    Zhu Hongjun; Xiong Shijie

    2010-01-01

    We investigate the dynamics of one electron wave packet in a linear chain with random on-site energies and a nonadiabatic electron-phonon interaction which is described by a delayed cubic nonlinear term in the time-dependent Schroedinger equation. We show that in the regime where the wave packet is delocalized in the case with only the delayed nonlinearity, the wave packet becomes localized when the disorder is added and the localization is enhanced by increasing the disorder. In the regime where the self-trapping phenomenon occurs in the case with only the delayed nonlinearity, by adding the disorder the general dynamical features of the wave packet do not change if the nonlinearity parameter is small, but the dynamics shows the subdiffusive behavior if the nonlinearity parameter is large. The numerical results demonstrate complicated wave packet dynamics of systems with both the disorder and nonlinearity.

  20. Non-intrusive Packet-Layer Model for Monitoring Video Quality of IPTV Services

    Science.gov (United States)

    Yamagishi, Kazuhisa; Hayashi, Takanori

    Developing a non-intrusive packet-layer model is required to passively monitor the quality of experience (QoE) during service. We propose a packet-layer model that can be used to estimate the video quality of IPTV using quality parameters derived from transmitted packet headers. The computational load of the model is lighter than that of the model that takes video signals and/or video-related bitstream information such as motion vectors as input. This model is applicable even if the transmitted bitstream information is encrypted because it uses transmitted packet headers rather than bitstream information. For developing the model, we conducted three extensive subjective quality assessments for different encoders and decoders (codecs), and video content. Then, we modeled the subjective video quality assessment characteristics based on objective features affected by coding and packet loss. Finally, we verified the model's validity by applying our model to unknown data sets different from training data sets used above.