Performance of Reverse-Link Synchronous DS-CDMA System on a Frequency-Selective Multipath Fading Channel with Imperfect Power Control

Directory of Open Access Journals (Sweden)

Duk Kyung Kim

2002-08-01

Full Text Available We analyze the performance for reverse-link synchronous DS-CDMA system in a frequency-selective Rayleigh fading channel with an imperfect power control scheme. The performance degradation due to power control error (PCE, which is approximated by a log-normally distributed random variable, is estimated as a function of the standard deviation of the PCE. In addition, we investigate the impacts of the multipath intensity profile (MIP shape and the number of resolvable paths on the performance. Finally, the coded bit error performance is evaluated in order to estimate the system capacity. Comparing with the conventional CDMA system, we show an achievable gain of from 59% to 23% for reverse-link synchronous transmission technique (RLSTT in the presence of imperfect power control over asynchronous transmission for BER=10−6. As well, the effect of tradeoff between orthogonality and diversity can be seen according to the number of multipaths, and the tendency is kept even in the presence of PCE. We conclude that the capacity can be further improved via the RLSTT, because the DS-CDMA system is very sensitive to power control imperfections.

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

Science.gov (United States)

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

2013-11-04

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

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

Directory of Open Access Journals (Sweden)

Huifang Chen

2013-11-01

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

Spectral Subtraction Approach for Interference Reduction of MIMO Channel Wireless Systems

Directory of Open Access Journals (Sweden)

Tomohiro Ono

2005-08-01

Full Text Available In this paper, a generalized spectral subtraction approach for reducing additive impulsive noise, narrowband signals, white Gaussian noise and DS-CDMA interferences in MIMO channel DS-CDMA wireless communication systems is investigated. The interference noise reduction or suppression is essential problem in wireless mobile communication systems to improve the quality of communication. The spectrum subtraction scheme is applied to the interference noise reduction problems for noisy MIMO channel systems. The interferences in space and time domain signals can effectively be suppressed by selecting threshold values, and the computational load with the FFT is not large. Further, the fading effects of channel are compensated by spectral modification with the spectral subtraction process. In the simulations, the effectiveness of the proposed methods for the MIMO channel DS-CDMA is shown to compare with the conventional MIMO channel DS-CDMA.

Wireless data link for FBTR

International Nuclear Information System (INIS)

Sundararajan, M.K.; Prabhakara Rao, G.; Ilango Sambasivan, S.; Swaminathan, P.; Ramakrishna, P.V.

2004-01-01

This paper deals with the design and development of a wireless data link for transmission of block pile signals at the Fast Breeder Test Reactor (FBTR) of Indira Gandhi Center for Atomic Research (IGCAR). This link is to establish wireless connectivity, typically at RS232C rates, over distances of the order of 50 m, and is expected to operate under electrically hostile conditions. (author)

Reconfigurable Signal Processing and Hardware Architecture for Broadband Wireless Communications

Directory of Open Access Journals (Sweden)

Liang Ying-Chang

2005-01-01

Full Text Available This paper proposes a broadband wireless transceiver which can be reconfigured to any type of cyclic-prefix (CP -based communication systems, including orthogonal frequency-division multiplexing (OFDM, single-carrier cyclic-prefix (SCCP system, multicarrier (MC code-division multiple access (MC-CDMA, MC direct-sequence CDMA (MC-DS-CDMA, CP-based CDMA (CP-CDMA, and CP-based direct-sequence CDMA (CP-DS-CDMA. A hardware platform is proposed and the reusable common blocks in such a transceiver are identified. The emphasis is on the equalizer design for mobile receivers. It is found that after block despreading operation, MC-DS-CDMA and CP-DS-CDMA have the same equalization blocks as OFDM and SCCP systems, respectively, therefore hardware and software sharing is possible for these systems. An attempt has also been made to map the functional reconfigurable transceiver onto the proposed hardware platform. The different functional entities which will be required to perform the reconfiguration and realize the transceiver are explained.

Symbol and Bit Error Rates Analysis of Hybrid PIM-CDMA

Directory of Open Access Journals (Sweden)

Ghassemlooy Z

2005-01-01

Full Text Available A hybrid pulse interval modulation code-division multiple-access (hPIM-CDMA scheme employing the strict optical orthogonal code (SOCC with unity and auto- and cross-correlation constraints for indoor optical wireless communications is proposed. In this paper, we analyse the symbol error rate (SER and bit error rate (BER of hPIM-CDMA. In the analysis, we consider multiple access interference (MAI, self-interference, and the hybrid nature of the hPIM-CDMA signal detection, which is based on the matched filter (MF. It is shown that the BER/SER performance can only be evaluated if the bit resolution conforms to the condition set by the number of consecutive false alarm pulses that might occur and be detected, so that one symbol being divided into two is unlikely to occur. Otherwise, the probability of SER and BER becomes extremely high and indeterminable. We show that for a large number of users, the BER improves when increasing the code weight . The results presented are compared with other modulation schemes.

High-Performance Wireless via the Merger of CI Chip-Shaped DS-CDMA and Oscillating-Beam Smart Antenna Arrays

Directory of Open Access Journals (Sweden)

Nassar Carl R

2004-01-01

Full Text Available We introduce a novel merger of direct sequence code division multiple access (DS-CDMA and smart antenna arrays. With regard to the DS-CDMA scheme, we employ carrier interferometry DS-CDMA (CI/DS-CDMA, a novel implementation of DS-CDMA where chips are decomposable into narrowband frequency components. With regard to the antenna array, we deploy the oscillating-beam smart array. Here, applying proper time-varying phases to the array elements, we create small movement (oscillation in the antenna array's pattern, while steering the antenna pattern main lobe to the position of the intended user. The oscillating antenna pattern creates a time-varying channel with a controllable coherence time. This, in turn, provides transmit diversity in the form of a time diversity gain at the mobile receiver side. At the receiver, three stages of combining are available: combining time components of the received signal within symbol duration (each experiencing a different fade to enhance performance via time diversity; combining frequency components which make up the CI/DS-CDMA chip to enhance the performance via frequency diversity; and combining across chips to eliminate the interfering users on the system. Merging CI/DS-CDMA with the oscillating-beam smart antenna at the base station, we achieve very high capacity via the merger of SDMA (available through directionality of the antenna array and code division multiple access (inherent in CI/DS-CDMA, and very high performance via the construction of receivers that exploit both transmit diversity and frequency diversity. We present the performance gains of the proposed merger.

A Brief Survey of Media Access Control, Data Link Layer, and Protocol Technologies for Lunar Surface Communications

Science.gov (United States)

Wallett, Thomas M.

2009-01-01

This paper surveys and describes some of the existing media access control and data link layer technologies for possible application in lunar surface communications and the advanced wideband Direct Sequence Code Division Multiple Access (DSCDMA) conceptual systems utilizing phased-array technology that will evolve in the next decade. Time Domain Multiple Access (TDMA) and Code Division Multiple Access (CDMA) are standard Media Access Control (MAC) techniques that can be incorporated into lunar surface communications architectures. Another novel hybrid technique that is recently being developed for use with smart antenna technology combines the advantages of CDMA with those of TDMA. The relatively new and sundry wireless LAN data link layer protocols that are continually under development offer distinct advantages for lunar surface applications over the legacy protocols which are not wireless. Also several communication transport and routing protocols can be chosen with characteristics commensurate with smart antenna systems to provide spacecraft communications for links exhibiting high capacity on the surface of the Moon. The proper choices depend on the specific communication requirements.

Dispersion Compensation Requirements for Optical CDMA Using WDM Lasers

International Nuclear Information System (INIS)

Mendez, A J; Hendandez, V J; Feng, H X C; Heritage, J P; Lennon, W J

2001-01-01

Optical code division multiple access (O-CDMA) uses very narrow transmission pulses and is thus susceptible to fiber optic link impairments. When the O-CDMA is implemented as wavelength/time (W/T) matrices which use wavelength division multiplexing (WDM) sources such as multi-frequency laser transmitters, the susceptibility may be higher due to: (a) the large bandwidth utilized and (b) the requirement that the various wavelength components of the codes be synchronized at the point of modulation and encoding as well as after (optical) correlation. A computer simulation based on the nonlinear Schroedinger equation, developed to study optical networking on the National Transparent Optical Network (NTON), was modified to characterize the impairments on the propagation and decoding of W/T matrix codes over a link of the NTON. Three critical link impairments were identified by the simulation: group velocity dispersion (GVD); the flatness of the optical amplifier gain; and the slope of the GVD. Subsequently, experiments were carried out on the NTON link to verify and refine the simulations as well as to suggest improvements in the W/T matrix signal processing design. The NTON link measurements quantified the O-CDMA dispersion compensation requirements. Dispersion compensation management is essential to assure the performance of W/T matrix codes

Principles of wireless access and localization

CERN Document Server

Pahlavan, Kaveh

2013-01-01

A comprehensive, encompassing and accessible text examining a wide range of key Wireless Networking and Localization technologies This book provides a unified treatment of issues related to all wireless access and wireless localization techniques.  The book reflects principles of design and deployment of infrastructure for wireless access and localization for wide, local, and personal networking.   Description of wireless access methods includes design and deployment of traditional TDMA and CDMA technologies and emerging Long Term Evolution (LTE) techniques for wide area cellular networks, the

Multi-Sensor Detection with Particle Swarm Optimization for Time-Frequency Coded Cooperative WSNs Based on MC-CDMA for Underground Coal Mines

Directory of Open Access Journals (Sweden)

Jingjing Xu

2015-08-01

Full Text Available In this paper, a wireless sensor network (WSN technology adapted to underground channel conditions is developed, which has important theoretical and practical value for safety monitoring in underground coal mines. According to the characteristics that the space, time and frequency resources of underground tunnel are open, it is proposed to constitute wireless sensor nodes based on multicarrier code division multiple access (MC-CDMA to make full use of these resources. To improve the wireless transmission performance of source sensor nodes, it is also proposed to utilize cooperative sensors with good channel conditions from the sink node to assist source sensors with poor channel conditions. Moreover, the total power of the source sensor and its cooperative sensors is allocated on the basis of their channel conditions to increase the energy efficiency of the WSN. To solve the problem that multiple access interference (MAI arises when multiple source sensors transmit monitoring information simultaneously, a kind of multi-sensor detection (MSD algorithm with particle swarm optimization (PSO, namely D-PSO, is proposed for the time-frequency coded cooperative MC-CDMA WSN. Simulation results show that the average bit error rate (BER performance of the proposed WSN in an underground coal mine is improved significantly by using wireless sensor nodes based on MC-CDMA, adopting time-frequency coded cooperative transmission and D-PSO algorithm with particle swarm optimization.

Multi-Sensor Detection with Particle Swarm Optimization for Time-Frequency Coded Cooperative WSNs Based on MC-CDMA for Underground Coal Mines.

Science.gov (United States)

Xu, Jingjing; Yang, Wei; Zhang, Linyuan; Han, Ruisong; Shao, Xiaotao

2015-08-27

In this paper, a wireless sensor network (WSN) technology adapted to underground channel conditions is developed, which has important theoretical and practical value for safety monitoring in underground coal mines. According to the characteristics that the space, time and frequency resources of underground tunnel are open, it is proposed to constitute wireless sensor nodes based on multicarrier code division multiple access (MC-CDMA) to make full use of these resources. To improve the wireless transmission performance of source sensor nodes, it is also proposed to utilize cooperative sensors with good channel conditions from the sink node to assist source sensors with poor channel conditions. Moreover, the total power of the source sensor and its cooperative sensors is allocated on the basis of their channel conditions to increase the energy efficiency of the WSN. To solve the problem that multiple access interference (MAI) arises when multiple source sensors transmit monitoring information simultaneously, a kind of multi-sensor detection (MSD) algorithm with particle swarm optimization (PSO), namely D-PSO, is proposed for the time-frequency coded cooperative MC-CDMA WSN. Simulation results show that the average bit error rate (BER) performance of the proposed WSN in an underground coal mine is improved significantly by using wireless sensor nodes based on MC-CDMA, adopting time-frequency coded cooperative transmission and D-PSO algorithm with particle swarm optimization.

Cross-Layer Design and Analysis of Downlink Communications in Cellular CDMA Systems

Directory of Open Access Journals (Sweden)

Sun Jin Yuan

2006-01-01

Full Text Available A cellular CDMA network with voice and data communications is considered. Focusing on the downlink direction, we seek for the overall performance improvement which can be achieved by cross-layer analysis and design, taking physical layer, link layer, network layer, and transport layer into account. We are concerned with the role of each single layer as well as the interaction among layers, and propose algorithms/schemes accordingly to improve the system performance. These proposals include adaptive scheduling for link layer, priority-based handoff strategy for network admission control, and an algorithm for the avoidance of TCP spurious timeouts at the transport layer. Numerical results show the performance gain of each proposed scheme over independent performance of an individual layer in the wireless mobile network. We conclude that the system performance in terms of capacity, throughput, dropping probability, outage, power efficiency, delay, and fairness can be enhanced by jointly considering the interactions across layers.

Nonlinearity effect of electro-optical modulator response in double spread CDMA radio-over-fiber transmissions

Science.gov (United States)

Huang, Jen-Fa; Yen, Chih-Ta; Li, Tzung-Yen

2008-07-01

This study presents a double-spread code-division multiple-access (CDMA) scheme for radio-over-fiber (RoF) transmissions. The network coder/decoders (codecs) are implemented using arrayed-waveguide grating (AWG) routers coded with maximal-length sequence ( M-sequence) codes. The effects of phase-induced intensity noise (PIIN) and multiple-access interference (MAI) on the system performance are evaluated numerically for different values of the optical modulation index (OMI) during the nonlinear electro-optical modulator (EOM) response. At low OMI optical device noise is dominant, but at high OMI nonlinear effect becomes significant. Numerical result shows that the system performance is highly sensitive to the OMI. Therefore, specifying an appropriate value of the OMI is essential in optimizing the system performance. The influence of the degree of polarization (DOP) in the system is also discussed. By employing the scrambler in front of the balanced photo-detector, the system performance can be enhanced. The high-performance, low-cost characteristics of the double-spread CDMA render the scheme an ideal solution for radio-CDMA wireless system cascaded with optical CDMA network.

Spread Spectrum Techniques and their Applications to Wireless Communications

DEFF Research Database (Denmark)

Prasad, Ramjee; Cianca, E.

2005-01-01

Spread Spectrum (SS) radio communications is on the verge of potentially explosive commercial development An SS-based multiple access, such as CDMA, has been chosen for 3G wireless communications. Other current applications of SS techniues are in Wireless LANs and Satellite Navigation Systems...

Performance Evaluation of a Novel CDMA Detection Technique: The Two-State Approach

Directory of Open Access Journals (Sweden)

Luca Simone Ronga

2005-04-01

Full Text Available The use of code division multiple access (CDMA makes third-generation wireless systems interference limited rather than noise limited. The research for new methods to reduce interference and increase efficiency lead us to formulate a signaling method where fast impulsive silence states are mapped on zero-energy symbols. The theoretical formulation of the optimum receiver is reported and the asymptotic multiuser efficiency (AME as well as an upper bound of the probability of error have been derived and applied to the conventional receiver and the decorrelating detector. Moreover, computer simulations have been performed to show the advantages of the proposed two-state scheme over the traditional single-state receiver in a multiuser CDMA system operating in a multipath fading channel.

Adaptive Space-Time-Spreading-Assisted Wideband CDMA Systems Communicating over Dispersive Nakagami- Fading Channels

Directory of Open Access Journals (Sweden)

Yang Lie-Liang

2005-01-01

Full Text Available In this contribution, the performance of wideband code-division multiple-access (W-CDMA systems using space-time-spreading- (STS- based transmit diversity is investigated, when frequency-selective Nakagami- fading channels, multiuser interference, and background noise are considered. The analysis and numerical results suggest that the achievable diversity order is the product of the frequency-selective diversity order and the transmit diversity order. Furthermore, both the transmit diversity and the frequency-selective diversity have the same order of importance. Since W-CDMA signals are subjected to frequency-selective fading, the number of resolvable paths at the receiver may vary over a wide range depending on the transmission environment encountered. It can be shown that, for wireless channels where the frequency selectivity is sufficiently high, transmit diversity may be not necessitated. Under this case, multiple transmission antennas can be leveraged into an increased bitrate. Therefore, an adaptive STS-based transmission scheme is then proposed for improving the throughput of W-CDMA systems. Our numerical results demonstrate that this adaptive STS-based transmission scheme is capable of significantly improving the effective throughput of W-CDMA systems. Specifically, the studied W-CDMA system's bitrate can be increased by a factor of three at the modest cost of requiring an extra 0.4 dB or 1.2 dB transmitted power in the context of the investigated urban or suburban areas, respectively.

Kalai-Smorodinsky bargaining solution for optimal resource allocation over wireless DS-CDMA visual sensor networks

Science.gov (United States)

Pandremmenou, Katerina; Kondi, Lisimachos P.; Parsopoulos, Konstantinos E.

2012-01-01

Surveillance applications usually require high levels of video quality, resulting in high power consumption. The existence of a well-behaved scheme to balance video quality and power consumption is crucial for the system's performance. In the present work, we adopt the game-theoretic approach of Kalai-Smorodinsky Bargaining Solution (KSBS) to deal with the problem of optimal resource allocation in a multi-node wireless visual sensor network (VSN). In our setting, the Direct Sequence Code Division Multiple Access (DS-CDMA) method is used for channel access, while a cross-layer optimization design, which employs a central processing server, accounts for the overall system efficacy through all network layers. The task assigned to the central server is the communication with the nodes and the joint determination of their transmission parameters. The KSBS is applied to non-convex utility spaces, efficiently distributing the source coding rate, channel coding rate and transmission powers among the nodes. In the underlying model, the transmission powers assume continuous values, whereas the source and channel coding rates can take only discrete values. Experimental results are reported and discussed to demonstrate the merits of KSBS over competing policies.

Design, comparative study and analysis of CDMA for different modulation techni

Directory of Open Access Journals (Sweden)

Arun Kumar

2015-11-01

Full Text Available In this work, we have design a MIMO–CDMA using 4 ∗ 8 antennas with the combination of MMSE (Minimum Mean square Error Equalizer for BPSK (Binary Phase shift Keying, QPSK (Quadrature Phase Shift Keying, 16-QAM, 64-QAM and 256-QAM (Quadrature Amplitude Modulation modulation schemes. The analysis is built on the basis of transmit–received signal, constellation and MMSE plot simulated on a MatLab/Simulink. On the basis of BER (Bit-Error-Rate, it is also concluded that this work is mostly suitable for high order modulation schemes as the BER of 16-qam, 64-QAM and 256-QAM is zero. The proposed study has increased the quality of the wireless link and Inter-Symbol-Interference (ISI is likewise cut by applying a combination of MMSE and MIMO (Multiple In and Multiple Out with OSTBC (Orthogonal space Time Block Code encoder and combiner.

Differential Space-Time Block Code Modulation for DS-CDMA Systems

Directory of Open Access Journals (Sweden)

Liu Jianhua

2002-01-01

Full Text Available A differential space-time block code (DSTBC modulation scheme is used to improve the performance of DS-CDMA systems in fast time-dispersive fading channels. The resulting scheme is referred to as the differential space-time block code modulation for DS-CDMA (DSTBC-CDMA systems. The new modulation and demodulation schemes are especially studied for the down-link transmission of DS-CDMA systems. We present three demodulation schemes, referred to as the differential space-time block code Rake (D-Rake receiver, differential space-time block code deterministic (D-Det receiver, and differential space-time block code deterministic de-prefix (D-Det-DP receiver, respectively. The D-Det receiver exploits the known information of the spreading sequences and their delayed paths deterministically besides the Rake type combination; consequently, it can outperform the D-Rake receiver, which employs the Rake type combination only. The D-Det-DP receiver avoids the effect of intersymbol interference and hence can offer better performance than the D-Det receiver.

Radial transfer of tracking data with wireless links

CERN Document Server

Pelikan, Daniel; Brenner, Richard; Dancila, Dragos; Gustafsson, Leif

2014-01-01

Wireless data transfer has revolutionized the consumer mar ket for the last decade giving products equipped with transmitters and receiver for wireless data t ransfer. Wireless technology has fea- tures attractive for data transfer in future tracking detec tors. The removal of wires and connectors for data links is certainly beneficial both for the material b udget and the reliability of the system. One other advantage is the freedom of routing signals which t oday is particularly complicated when bringing the data the first 50 cm outside the tracker. Wit h wireless links intelligence can be built into a tracker by introducing communication betwee n tracking layers within a Region Of Interest which would allow the construction of track primit ives in real time. The wireless signal is transmitted by a passive antenna structure which is a radiat ion hard and much less complex object than an optical link. Due to the requirement of high data rate s in detectors a high bandwidth is required. The frequency band aro...

MAI statistics estimation and analysis in a DS-CDMA system

Science.gov (United States)

Alami Hassani, A.; Zouak, M.; Mrabti, M.; Abdi, F.

2018-05-01

A primary limitation of Direct Sequence Code Division Multiple Access DS-CDMA link performance and system capacity is multiple access interference (MAI). To examine the performance of CDMA systems in the presence of MAI, i.e., in a multiuser environment, several works assumed that the interference can be approximated by a Gaussian random variable. In this paper, we first develop a new and simple approach to characterize the MAI in a multiuser system. In addition to statistically quantifying the MAI power, the paper also proposes a statistical model for both variance and mean of the MAI for synchronous and asynchronous CDMA transmission. We show that the MAI probability density function (PDF) is Gaussian for the equal-received-energy case and validate it by computer simulations.

Optical CDMA components requirements

Science.gov (United States)

Chan, James K.

1998-08-01

Optical CDMA is a complementary multiple access technology to WDMA. Optical CDMA potentially provides a large number of virtual optical channels for IXC, LEC and CLEC or supports a large number of high-speed users in LAN. In a network, it provides asynchronous, multi-rate, multi-user communication with network scalability, re-configurability (bandwidth on demand), and network security (provided by inherent CDMA coding). However, optical CDMA technology is less mature in comparison to WDMA. The components requirements are also different from WDMA. We have demonstrated a video transport/switching system over a distance of 40 Km using discrete optical components in our laboratory. We are currently pursuing PIC implementation. In this paper, we will describe the optical CDMA concept/features, the demonstration system, and the requirements of some critical optical components such as broadband optical source, broadband optical amplifier, spectral spreading/de- spreading, and fixed/programmable mask.

Analysis of PPM-CDMA and OPPM-CDMA communication systems with new optical code

Science.gov (United States)

Liu, F.; Ghafouri-Shiraz, H.

2005-11-01

A novel type of optical spreading sequences, named the 'new-Modified Prime Code (nMPC)', is proposed for use in synchronous direct-detection optical code-division multiple-access (CDMA) systems which employ both pulse position modulation (PPM) and overlapping pulse position modulation (OPPM) schemes. The upper bounds on the bit error rate (BER) for nMPC used in PPM-CDMA systems are derived and compared with the respective systems, using a modified prime code (MPC) and a padded modified prime code (PMPC). The nMPC is further applied to the OPPM-CDMA system and the system with a proposed interference cancellation scheme. Our results show that under the same conditions the PPM-CDMA system performances are more improved with the use of nMPC than with the two other traditional codes. Moreover, they show that the system performances are significantly enhanced by the proposed interference reduction methods, if the nMPC is used in the OPPM-CDMA systems.

Link Investigation of IEEE 802.15.4 Wireless Sensor Networks in Forests.

Science.gov (United States)

Ding, Xingjian; Sun, Guodong; Yang, Gaoxiang; Shang, Xinna

2016-06-27

Wireless sensor networks are expected to automatically monitor the ecological evolution and wildlife habits in forests. Low-power links (transceivers) are often adopted in wireless sensor network applications, in order to save the precious sensor energy and then achieve long-term, unattended monitoring. Recent research has presented some performance characteristics of such low-power wireless links under laboratory or outdoor scenarios with less obstacles, and they have found that low-power wireless links are unreliable and prone to be affected by the target environment. However, there is still less understanding about how well the low-power wireless link performs in real-world forests and to what extent the complex in-forest surrounding environments affect the link performances. In this paper, we empirically evaluate the low-power links of wireless sensors in three typical different forest environments. Our experiment investigates the performance of the link layer compatible with the IEEE 802.15.4 standard and analyzes the variation patterns of the packet reception ratio (PRR), the received signal strength indicator (RSSI) and the link quality indicator (LQI) under diverse experimental settings. Some observations of this study are inconsistent with or even contradict prior results that are achieved in open fields or relatively clean environments and thus, provide new insights both into effectively evaluating the low-power wireless links and into efficiently deploying wireless sensor network systems in forest environments.

A performance analysis of DS-CDMA and SCPC VSAT networks

Science.gov (United States)

Hayes, David P.; Ha, Tri T.

1990-01-01

Spread-spectrum and single-channel-per-carrier (SCPC) transmission techniques work well in very small aperture terminal (VSAT) networks for multiple-access purposes while allowing the earth station antennas to remain small. Direct-sequence code-division multiple-access (DS-CDMA) is the simplest spread-spectrum technique to use in a VSAT network since a frequency synthesizer is not required for each terminal. An examination is made of the DS-CDMA and SCPC Ku-band VSAT satellite systems for low-density (64-kb/s or less) communications. A method for improving the standardf link analysis of DS-CDMA satellite-switched networks by including certain losses is developed. The performance of 50-channel full mesh and star network architectures is analyzed. The selection of operating conditions producing optimum performance is demonstrated.

TULIP: A Link-Level Protocol for Improving TCP over Wireless Links

National Research Council Canada - National Science Library

Parsa, Christina; Garcia-Luna-Aceves, J. J

1999-01-01

We present the transport unaware link improvement protocol (TULIP), which dramatically improves the performance of TCP over lossy wireless links, without competing with or modifying the transport- or network-layer protocols...

Equivalence of Linear MMSE Detection in DS-CDMA and MC-CDMA Systems over Time and Frequency Selective Channels

Directory of Open Access Journals (Sweden)

Tamer A. Kadous

2003-01-01

Full Text Available The goal of this paper is to compare the performance of the linear minimum mean square error (MMSE detector for a class of code division multiple access (CDMA systems in time and frequency selective channels. Specifically, we consider direct sequence (DS-CDMA, multicarrier (MC-CDMA, and the MC-DS-CDMA systems. Two key tools are used in our development. First, a general time-frequency framework that includes the different CDMA systems as special cases. Second, the duality between time and frequency domains that is used to derive equivalences between the different CDMA systems operating over purely frequency selective and purely time selective channels. We then combine the insights obtained from these special cases to assess the performance of CDMA systems over time and frequency selective channels. We provide sufficient conditions for the codes employed by the CDMA systems for the equivalences to hold. Numerical results are presented to illustrate the results.

Time of Arrival Estimation in Probability-Controlled Generalized CDMA Systems

Directory of Open Access Journals (Sweden)

Hagit Messer

2007-11-01

Full Text Available In recent years, more and more wireless communications systems are required to provide also a positioning measurement. In code division multiple access (CDMA communication systems, the positioning accuracy is significantly degraded by the multiple access interference (MAI caused by other users in the system. This MAI is commonly managed by a power control mechanism, and yet, MAI has a major effect on positioning accuracy. Probability control is a recently introduced interference management mechanism. In this mechanism, a user with excess power chooses not to transmit some of its symbols. The information in the nontransmitted symbols is recovered by an error-correcting code (ECC, while all other users receive a more reliable data during these quiet periods. Previous research had shown that the implementation of a probability control mechanism can significantly reduce the MAI. In this paper, we show that probability control also improves the positioning accuracy. We focus on time-of-arrival (TOA based positioning systems. We analyze the TOA estimation performance in a generalized CDMA system, in which the probability control mechanism is employed, where the transmitted signal is noncontinuous with a symbol transmission probability smaller than 1. The accuracy of the TOA estimation is determined using appropriate modifications of the Cramer-Rao bound on the delay estimation. Keeping the average transmission power constant, we show that the TOA accuracy of each user does not depend on its transmission probability, while being a nondecreasing function of the transmission probability of any other user. Therefore, a generalized, noncontinuous CDMA system with a probability control mechanism can always achieve better positioning performance, for all users in the network, than a conventional, continuous, CDMA system.

A wireless laser displacement sensor node for structural health monitoring.

Science.gov (United States)

Park, Hyo Seon; Kim, Jong Moon; Choi, Se Woon; Kim, Yousok

2013-09-30

This study describes a wireless laser displacement sensor node that measures displacement as a representative damage index for structural health monitoring (SHM). The proposed measurement system consists of a laser displacement sensor (LDS) and a customized wireless sensor node. Wireless communication is enabled by a sensor node that consists of a sensor module, a code division multiple access (CDMA) communication module, a processor, and a power module. An LDS with a long measurement distance is chosen to increase field applicability. For a wireless sensor node driven by a battery, we use a power control module with a low-power processor, which facilitates switching between the sleep and active modes, thus maximizing the power consumption efficiency during non-measurement and non-transfer periods. The CDMA mode is also used to overcome the limitation of communication distance, which is a challenge for wireless sensor networks and wireless communication. To evaluate the reliability and field applicability of the proposed wireless displacement measurement system, the system is tested onsite to obtain the required vertical displacement measurements during the construction of mega-trusses and an edge truss, which are the primary structural members in a large-scale irregular building currently under construction. The measurement values confirm the validity of the proposed wireless displacement measurement system and its potential for use in safety evaluations of structural elements.

A Wireless Laser Displacement Sensor Node for Structural Health Monitoring

Directory of Open Access Journals (Sweden)

Se Woon Choi

2013-09-01

Full Text Available This study describes a wireless laser displacement sensor node that measures displacement as a representative damage index for structural health monitoring (SHM. The proposed measurement system consists of a laser displacement sensor (LDS and a customized wireless sensor node. Wireless communication is enabled by a sensor node that consists of a sensor module, a code division multiple access (CDMA communication module, a processor, and a power module. An LDS with a long measurement distance is chosen to increase field applicability. For a wireless sensor node driven by a battery, we use a power control module with a low-power processor, which facilitates switching between the sleep and active modes, thus maximizing the power consumption efficiency during non-measurement and non-transfer periods. The CDMA mode is also used to overcome the limitation of communication distance, which is a challenge for wireless sensor networks and wireless communication. To evaluate the reliability and field applicability of the proposed wireless displacement measurement system, the system is tested onsite to obtain the required vertical displacement measurements during the construction of mega-trusses and an edge truss, which are the primary structural members in a large-scale irregular building currently under construction. The measurement values confirm the validity of the proposed wireless displacement measurement system and its potential for use in safety evaluations of structural elements.

Zero-Forcing and Minimum Mean-Square Error Multiuser Detection in Generalized Multicarrier DS-CDMA Systems for Cognitive Radio

Directory of Open Access Journals (Sweden)

Lie-Liang Yang

2008-01-01

Full Text Available In wireless communications, multicarrier direct-sequence code-division multiple access (MC DS-CDMA constitutes one of the highly flexible multiple access schemes. MC DS-CDMA employs a high number of degrees-of-freedom, which are beneficial to design and reconfiguration for communications in dynamic communications environments, such as in the cognitive radios. In this contribution, we consider the multiuser detection (MUD in MC DS-CDMA, which motivates lowcomplexity, high flexibility, and robustness so that the MUD schemes are suitable for deployment in dynamic communications environments. Specifically, a range of low-complexity MUDs are derived based on the zero-forcing (ZF, minimum mean-square error (MMSE, and interference cancellation (IC principles. The bit-error rate (BER performance of the MC DS-CDMA aided by the proposed MUDs is investigated by simulation approaches. Our study shows that, in addition to the advantages provided by a general ZF, MMSE, or IC-assisted MUD, the proposed MUD schemes can be implemented using modular structures, where most modules are independent of each other. Due to the independent modular structure, in the proposed MUDs one module may be reconfigured without yielding impact on the others. Therefore, the MC DS-CDMA, in conjunction with the proposed MUDs, constitutes one of the promising multiple access schemes for communications in the dynamic communications environments such as in the cognitive radios.

Zero-Forcing and Minimum Mean-Square Error Multiuser Detection in Generalized Multicarrier DS-CDMA Systems for Cognitive Radio

Directory of Open Access Journals (Sweden)

Wang Li-Chun

2008-01-01

Full Text Available Abstract In wireless communications, multicarrier direct-sequence code-division multiple access (MC DS-CDMA constitutes one of the highly flexible multiple access schemes. MC DS-CDMA employs a high number of degrees-of-freedom, which are beneficial to design and reconfiguration for communications in dynamic communications environments, such as in the cognitive radios. In this contribution, we consider the multiuser detection (MUD in MC DS-CDMA, which motivates lowcomplexity, high flexibility, and robustness so that the MUD schemes are suitable for deployment in dynamic communications environments. Specifically, a range of low-complexity MUDs are derived based on the zero-forcing (ZF, minimum mean-square error (MMSE, and interference cancellation (IC principles. The bit-error rate (BER performance of the MC DS-CDMA aided by the proposed MUDs is investigated by simulation approaches. Our study shows that, in addition to the advantages provided by a general ZF, MMSE, or IC-assisted MUD, the proposed MUD schemes can be implemented using modular structures, where most modules are independent of each other. Due to the independent modular structure, in the proposed MUDs one module may be reconfigured without yielding impact on the others. Therefore, the MC DS-CDMA, in conjunction with the proposed MUDs, constitutes one of the promising multiple access schemes for communications in the dynamic communications environments such as in the cognitive radios.

Transmission Delay Based Control over Networks with Wireless Links

Institute of Scientific and Technical Information of China (English)

无

2002-01-01

To achieve the mobility of computers during communication, the TCP connections between fixed host and mobile host may often traverse wired and wireless networks, and the recovery of losses due to wireless transmission error is much different from congestion control. The paper analyzes the side effect of RTT estimation while making the TCP source to handle congestion and wireless error losses properly. Then present a strategy using information feedback by the last hop acknowledgement and monitoring the queuing level of the wired bottleneck link by calculating the changes in transmission delay along the path. With the identification of the early stage of congestion, it can respond to wired congestion quickly while keeping wireless link more reliable, and make TCP react to the different packets losses more appropriately.

E- and W-band high-capacity hybrid fiber-wireless link

DEFF Research Database (Denmark)

Vegas Olmos, Juan José; Pang, Xiaodan; Tafur Monroy, Idelfonso

2014-01-01

In this paper we summarize the work conducted in our group in the area of E- and W-band optical high-capacity fiber-wireless links. We present performance evaluations of E- and W-band mm-wave signal generation using photonic frequency upconversion employing both VCSELs and ECLs, along with transm...... in mobile backhaul/fronthaul applications, dense distributed antenna systems and fiber-over-radio scenarios.......In this paper we summarize the work conducted in our group in the area of E- and W-band optical high-capacity fiber-wireless links. We present performance evaluations of E- and W-band mm-wave signal generation using photonic frequency upconversion employing both VCSELs and ECLs, along...... with transmission over different type of optical fibers and for a number of values for the wireless link distance. Hybrid wireless-optical links can be composed of mature and resilient technology available off-the-shelf, and provide functionalities that can add value to optical access networks, specifically...

The Effects of Spatial Diversity and Imperfect Channel Estimation on Wideband MC-DS-CDMA and MC-CDMA

Science.gov (United States)

2009-10-01

In our previous work, we compared the theoretical bit error rates of multi-carrier direct sequence code division multiple access (MC- DS - CDMA ) and...consider only those cases where MC- CDMA has higher frequency diversity than MC- DS - CDMA . Since increases in diversity yield diminishing gains, we conclude

Multimedia transmission in MC-CDMA using adaptive subcarrier power allocation and CFO compensation

Science.gov (United States)

Chitra, S.; Kumaratharan, N.

2018-02-01

Multicarrier code division multiple access (MC-CDMA) system is one of the most effective techniques in fourth-generation (4G) wireless technology, due to its high data rate, high spectral efficiency and resistance to multipath fading. However, MC-CDMA systems are greatly deteriorated by carrier frequency offset (CFO) which is due to Doppler shift and oscillator instabilities. It leads to loss of orthogonality among the subcarriers and causes intercarrier interference (ICI). Water filling algorithm (WFA) is an efficient resource allocation algorithm to solve the power utilisation problems among the subcarriers in time-dispersive channels. The conventional WFA fails to consider the effect of CFO. To perform subcarrier power allocation with reduced CFO and to improve the capacity of MC-CDMA system, residual CFO compensated adaptive subcarrier power allocation algorithm is proposed in this paper. The proposed technique allocates power only to subcarriers with high channel to noise power ratio. The performance of the proposed method is evaluated using random binary data and image as source inputs. Simulation results depict that the bit error rate performance and ICI reduction capability of the proposed modified WFA offered superior performance in both power allocation and image compression for high-quality multimedia transmission in the presence of CFO and imperfect channel state information conditions.

Impact of Different Spreading Codes Using FEC on DWT Based MC-CDMA System

OpenAIRE

Masum, Saleh; Kabir, M. Hasnat; Islam, Md. Matiqul; Shams, Rifat Ara; Ullah, Shaikh Enayet

2012-01-01

The effect of different spreading codes in DWT based MC-CDMA wireless communication system is investigated. In this paper, we present the Bit Error Rate (BER) performance of different spreading codes (Walsh-Hadamard code, Orthogonal gold code and Golay complementary sequences) using Forward Error Correction (FEC) of the proposed system. The data is analyzed and is compared among different spreading codes in both coded and uncoded cases. It is found via computer simulation that the performance...

Forward Link Power Control Strategy and its Optimum Issue in CDMA Cellular Networks

Institute of Scientific and Technical Information of China (English)

无

2000-01-01

In this paper, we propose a theoretical method in order to estimate the forward link outage probability and user capacity of a cellular system which are based on IS-95 CDMA standard, especialy impact of power control strategy and voice activity monitoring in the system under long-term fading effects, in which the light and heavy fadings are considered. According to the numerical results obtained in this paper, the power control strategy leads to approximately the threefold user capacity in contrast to the situation without power control strategy. The reults are compared with Interference-to-Signal Ratio (ISR) driven power control scheme[6][9] which can be used only for simulation of the system. The power control strategy not only improves the desired signal to the interference ratio in the reference user's receiver, but also offers uniform service to the user wherever it is located in the cell.

Development of a mobile emergency patient information and imaging communication system based on CDMA-1X EVDO

Science.gov (United States)

Yang, Keon Ho; Jung, Haijo; Kang, Won-Suk; Jang, Bong Mun; Kim, Joong Il; Han, Dong Hoon; Yoo, Sun-Kook; Yoo, Hyung-Sik; Kim, Hee-Joung

2006-03-01

The wireless mobile service with a high bit rate using CDMA-1X EVDO is now widely used in Korea. Mobile devices are also increasingly being used as the conventional communication mechanism. We have developed a web-based mobile system that communicates patient information and images, using CDMA-1X EVDO for emergency diagnosis. It is composed of a Mobile web application system using the Microsoft Windows 2003 server and an internet information service. Also, a mobile web PACS used for a database managing patient information and images was developed by using Microsoft access 2003. A wireless mobile emergency patient information and imaging communication system is developed by using Microsoft Visual Studio.NET, and JPEG 2000 ActiveX control for PDA phone was developed by using the Microsoft Embedded Visual C++. Also, the CDMA-1X EVDO is used for connections between mobile web servers and the PDA phone. This system allows fast access to the patient information database, storing both medical images and patient information anytime and anywhere. Especially, images were compressed into a JPEG2000 format and transmitted from a mobile web PACS inside the hospital to the radiologist using a PDA phone located outside the hospital. Also, this system shows radiological images as well as physiological signal data, including blood pressure, vital signs and so on, in the web browser of the PDA phone so radiologists can diagnose more effectively. Also, we acquired good results using an RW-6100 PDA phone used in the university hospital system of the Sinchon Severance Hospital in Korea.

Performance Analysis of Wavelet Based MC-CDMA System with Implementation of Various Antenna Diversity Schemes

OpenAIRE

Islam, Md. Matiqul; Kabir, M. Hasnat; Ullah, Sk. Enayet

2012-01-01

The impact of using wavelet based technique on the performance of a MC-CDMA wireless communication system has been investigated. The system under proposed study incorporates Walsh Hadamard codes to discriminate the message signal for individual user. A computer program written in Mathlab source code is developed and this simulation study is made with implementation of various antenna diversity schemes and fading (Rayleigh and Rician) channel. Computer simulation results demonstrate that the p...

A mean field theory of coded CDMA systems

International Nuclear Information System (INIS)

Yano, Toru; Tanaka, Toshiyuki; Saad, David

2008-01-01

We present a mean field theory of code-division multiple-access (CDMA) systems with error-control coding. On the basis of the relation between the free energy and mutual information, we obtain an analytical expression of the maximum spectral efficiency of the coded CDMA system, from which a mean-field description of the coded CDMA system is provided in terms of a bank of scalar Gaussian channels whose variances in general vary at different code symbol positions. Regular low-density parity-check (LDPC)-coded CDMA systems are also discussed as an example of the coded CDMA systems

A mean field theory of coded CDMA systems

Energy Technology Data Exchange (ETDEWEB)

Yano, Toru [Graduate School of Science and Technology, Keio University, Hiyoshi, Kohoku-ku, Yokohama-shi, Kanagawa 223-8522 (Japan); Tanaka, Toshiyuki [Graduate School of Informatics, Kyoto University, Yoshida Hon-machi, Sakyo-ku, Kyoto-shi, Kyoto 606-8501 (Japan); Saad, David [Neural Computing Research Group, Aston University, Birmingham B4 7ET (United Kingdom)], E-mail: yano@thx.appi.keio.ac.jp

2008-08-15

We present a mean field theory of code-division multiple-access (CDMA) systems with error-control coding. On the basis of the relation between the free energy and mutual information, we obtain an analytical expression of the maximum spectral efficiency of the coded CDMA system, from which a mean-field description of the coded CDMA system is provided in terms of a bank of scalar Gaussian channels whose variances in general vary at different code symbol positions. Regular low-density parity-check (LDPC)-coded CDMA systems are also discussed as an example of the coded CDMA systems.

Optimal power allocation and joint source-channel coding for wireless DS-CDMA visual sensor networks

Science.gov (United States)

Pandremmenou, Katerina; Kondi, Lisimachos P.; Parsopoulos, Konstantinos E.

2011-01-01

In this paper, we propose a scheme for the optimal allocation of power, source coding rate, and channel coding rate for each of the nodes of a wireless Direct Sequence Code Division Multiple Access (DS-CDMA) visual sensor network. The optimization is quality-driven, i.e. the received quality of the video that is transmitted by the nodes is optimized. The scheme takes into account the fact that the sensor nodes may be imaging scenes with varying levels of motion. Nodes that image low-motion scenes will require a lower source coding rate, so they will be able to allocate a greater portion of the total available bit rate to channel coding. Stronger channel coding will mean that such nodes will be able to transmit at lower power. This will both increase battery life and reduce interference to other nodes. Two optimization criteria are considered. One that minimizes the average video distortion of the nodes and one that minimizes the maximum distortion among the nodes. The transmission powers are allowed to take continuous values, whereas the source and channel coding rates can assume only discrete values. Thus, the resulting optimization problem lies in the field of mixed-integer optimization tasks and is solved using Particle Swarm Optimization. Our experimental results show the importance of considering the characteristics of the video sequences when determining the transmission power, source coding rate and channel coding rate for the nodes of the visual sensor network.

CDMA

International Nuclear Information System (INIS)

Ock, Yun Cheol

2003-07-01

This book is comprised of summary of mobile communication : CT, TRS, Cellular mobile communication, digital communication, Is-95 and Friedns and PCS system, Basic concept : tools of mathematics, system, signal analysis of Fourier, Sampling, DB and Bandwidth, noise and OSI 7 Layer, DSSS and Code theory : spread spectrum, CDM/CDMA communication mode, code theory and PN code, CDMA Demodulator : Searcher engine, function by searcher engine, Finger demodulator and searcher task, control power : the reason for forward control power and reverse control power, open loop power control, closed loop power control and outer loop power control, Hand off : Parameter for hand off MASHO, new soft hand off, hard hand off, MAHHO and Access hand off, Radio transmission technique : interleaving and Modulation, Is-95, COMA 2000 : COMA 2000 System, Idle state and registration, vocoder : voice source coding and QCELP

Reduced-Rank Chip-Level MMSE Equalization for the 3G CDMA Forward Link with Code-Multiplexed Pilot

Directory of Open Access Journals (Sweden)

Goldstein J Scott

2002-01-01

Full Text Available This paper deals with synchronous direct-sequence code-division multiple access (CDMA transmission using orthogonal channel codes in frequency selective multipath, motivated by the forward link in 3G CDMA systems. The chip-level minimum mean square error (MMSE estimate of the (multiuser synchronous sum signal transmitted by the base, followed by a correlate and sum, has been shown to perform very well in saturated systems compared to a Rake receiver. In this paper, we present the reduced-rank, chip-level MMSE estimation based on the multistage nested Wiener filter (MSNWF. We show that, for the case of a known channel, only a small number of stages of the MSNWF is needed to achieve near full-rank MSE performance over a practical single-to-noise ratio (SNR range. This holds true even for an edge-of-cell scenario, where two base stations are contributing near equal-power signals, as well as for the single base station case. We then utilize the code-multiplexed pilot channel to train the MSNWF coefficients and show that adaptive MSNWF operating in a very low rank subspace performs slightly better than full-rank recursive least square (RLS and significantly better than least mean square (LMS. An important advantage of the MSNWF is that it can be implemented in a lattice structure, which involves significantly less computation than RLS. We also present structured MMSE equalizers that exploit the estimate of the multipath arrival times and the underlying channel structure to project the data vector onto a much lower dimensional subspace. Specifically, due to the sparseness of high-speed CDMA multipath channels, the channel vector lies in the subspace spanned by a small number of columns of the pulse shaping filter convolution matrix. We demonstrate that the performance of these structured low-rank equalizers is much superior to unstructured equalizers in terms of convergence speed and error rates.

Invited Article: Channel performance for indoor and outdoor terahertz wireless links

Science.gov (United States)

Ma, Jianjun; Shrestha, Rabi; Moeller, Lothar; Mittleman, Daniel M.

2018-05-01

One of the most exciting future applications of terahertz technology is in the area of wireless communications. As 5G systems incorporating a standard for millimeter-wave wireless links approach commercial roll-out, it is becoming clear that even this new infrastructure will not be sufficient to keep pace with the rapidly increasing global demand for bandwidth. One favorable solution that is attracting increasing attention for subsequent generations of wireless technology is to use higher frequencies, above 100 GHz. The implementation of such links will require significant advances in hardware, algorithms, and architecture. Although numerous research groups are exploring aspects of this challenging problem, many basic questions remain unaddressed. Here, we present an experimental effort to characterize THz wireless links in both indoor and outdoor environments. We report measurements at 100, 200, 300, and 400 GHz, using a link with a data rate of 1 Gbit/s. We demonstrate both line-of-sight and non-line-of-sight (specular reflection) links off of interior building walls. This work represents a first step to establish the feasibility of using THz carrier waves for data transmission in diverse situations and environments.

Coding-Spreading Tradeoff in CDMA Systems

National Research Council Canada - National Science Library

Bolas, Eduardo

2002-01-01

.... Comparing different combinations of coding and spreading with a traditional DS-CDMA, as defined in the IS-95 standard, allows the criteria to be defined for the best coding-spreading tradeoff in CDMA systems...

PDA-phone-based instant transmission of radiological images over a CDMA network by combining the PACS screen with a Bluetooth-interfaced local wireless link.

Science.gov (United States)

Kim, Dong Keun; Yoo, Sun K; Park, Jeong Jin; Kim, Sun Ho

2007-06-01

Remote teleconsultation by specialists is important for timely, correct, and specialized emergency surgical and medical decision making. In this paper, we designed a new personal digital assistant (PDA)-phone-based emergency teleradiology system by combining cellular communication with Bluetooth-interfaced local wireless links. The mobility and portability resulting from the use of PDAs and wireless communication can provide a more effective means of emergency teleconsultation without requiring the user to be limited to a fixed location. Moreover, it enables synchronized radiological image sharing between the attending physician in the emergency room and the remote specialist on picture archiving and communication system terminals without distorted image acquisition. To enable rapid and fine-quality radiological image transmission over a cellular network in a secure manner, progressive compression and security mechanisms have been incorporated. The proposed system is tested over a code division Multiple Access 1x-Evolution Data-Only network to evaluate the performance and to demonstrate the feasibility of this system in a real-world setting.

Sequence Selection and Performance in DS/CDMA Systems

Directory of Open Access Journals (Sweden)

Jefferson Santos Ambrosio

2016-03-01

Full Text Available In this work key concepts on coding division multiple access (CDMA communication systems have been discussed. The sequence selection impact on the performance and capacity of direct sequence CDMA (DS/CDMA systems under AWGN and increasing system loading, as well as under multiple antennas channels was investigated.

Effects of optical layer impairments on 2.5 Gb/s optical CDMA transmission.

Science.gov (United States)

Feng, H; Mendez, A; Heritage, J; Lennon, W

2000-07-03

We conducted a computer simulation study to assess the effects of optical layer impairments on optical CDMA (O-CDMA) transmission of 8 asynchronous users at 2.5 Gb/s each user over a 214-km link. It was found that with group velocity dispersion compensation, two other residual effects, namely, the nonzero chromatic dispersion slope of the single mode fiber (which causes skew) and the non-uniform EDFA gain (which causes interference power level to exceed signal power level of some codes) degrade the signal to multi-access interference (MAI) ratio. In contrast, four wave mixing and modulation due to the Kerr and Raman contributions to the fiber nonlinear refractive index are less important. Current wavelength-division multiplexing (WDM) technologies, including dispersion management, EDFA gain flattening, and 3 rd order dispersion compensation, are sufficient to overcome the impairments to the O-CDMA transmission system that we considered.

High-Capacity Hybrid Optical Fiber-Wireless Communications Links in Access Networks

DEFF Research Database (Denmark)

Pang, Xiaodan

of broadband services access. To realize the seamless convergence between the two network segments, the lower capacity of wireless systems need to be increased to match the continuously increasing bandwidth of fiber-optic systems. The research works included in this thesis are devoted to experimental...... investigations of photonic-wireless links with record high capacities to fulfill the requirements of next generation hybrid optical fiber-wireless access networks. The main contributions of this thesis have expanded the state-of-the-art in two main areas: high speed millimeter-wave (mm-wave) communication links......Integration between fiber-optic and wireless communications systems in the "last mile" access networks is currently considered as a promising solution for both service providers and users, in terms of minimizing deployment cost, shortening upgrading period and increasing mobility and flexibility...

Performance prediction of a synchronization link for distributed aerospace wireless systems.

Science.gov (United States)

Wang, Wen-Qin; Shao, Huaizong

2013-01-01

For reasons of stealth and other operational advantages, distributed aerospace wireless systems have received much attention in recent years. In a distributed aerospace wireless system, since the transmitter and receiver placed on separated platforms which use independent master oscillators, there is no cancellation of low-frequency phase noise as in the monostatic cases. Thus, high accurate time and frequency synchronization techniques are required for distributed wireless systems. The use of a dedicated synchronization link to quantify and compensate oscillator frequency instability is investigated in this paper. With the mathematical statistical models of phase noise, closed-form analytic expressions for the synchronization link performance are derived. The possible error contributions including oscillator, phase-locked loop, and receiver noise are quantified. The link synchronization performance is predicted by utilizing the knowledge of the statistical models, system error contributions, and sampling considerations. Simulation results show that effective synchronization error compensation can be achieved by using this dedicated synchronization link.

Providing end-to-end QoS for multimedia applications in 3G wireless networks

Science.gov (United States)

Guo, Katherine; Rangarajan, Samapth; Siddiqui, M. A.; Paul, Sanjoy

2003-11-01

As the usage of wireless packet data services increases, wireless carriers today are faced with the challenge of offering multimedia applications with QoS requirements within current 3G data networks. End-to-end QoS requires support at the application, network, link and medium access control (MAC) layers. We discuss existing CDMA2000 network architecture and show its shortcomings that prevent supporting multiple classes of traffic at the Radio Access Network (RAN). We then propose changes in RAN within the standards framework that enable support for multiple traffic classes. In addition, we discuss how Session Initiation Protocol (SIP) can be augmented with QoS signaling for supporting end-to-end QoS. We also review state of the art scheduling algorithms at the base station and provide possible extensions to these algorithms to support different classes of traffic as well as different classes of users.

Consistent sensor, relay, and link selection in wireless sensor networks

NARCIS (Netherlands)

Arroyo Valles, M.D.R.; Simonetto, A.; Leus, G.J.T.

2017-01-01

In wireless sensor networks, where energy is scarce, it is inefficient to have all nodes active because they consume a non-negligible amount of battery. In this paper we consider the problem of jointly selecting sensors, relays and links in a wireless sensor network where the active sensors need

Orthogonal Multi-Carrier DS-CDMA with Frequency-Domain Equalization

Science.gov (United States)

Tanaka, Ken; Tomeba, Hiromichi; Adachi, Fumiyuki

Orthogonal multi-carrier direct sequence code division multiple access (orthogonal MC DS-CDMA) is a combination of orthogonal frequency division multiplexing (OFDM) and time-domain spreading, while multi-carrier code division multiple access (MC-CDMA) is a combination of OFDM and frequency-domain spreading. In MC-CDMA, a good bit error rate (BER) performance can be achieved by using frequency-domain equalization (FDE), since the frequency diversity gain is obtained. On the other hand, the conventional orthogonal MC DS-CDMA fails to achieve any frequency diversity gain. In this paper, we propose a new orthogonal MC DS-CDMA that can obtain the frequency diversity gain by applying FDE. The conditional BER analysis is presented. The theoretical average BER performance in a frequency-selective Rayleigh fading channel is evaluated by the Monte-Carlo numerical computation method using the derived conditional BER and is confirmed by computer simulation of the orthogonal MC DS-CDMA signal transmission.

Design and Implementation of Dual-Mode Wireless Video Monitoring System

Directory of Open Access Journals (Sweden)

BAO Song-Jian

2014-10-01

Full Text Available Dual-mode wireless video transmission has two major problems. Firstly, one is time delay difference bringing about asynchronous reception decoding frame error phenomenon; secondly, dual-mode network bandwidth inconformity causes scheduling problem. In order to solve above two problems, a kind of TD-SCDMA/CDMA20001x dual-mode wireless video transmission design method is proposed. For the solution of decoding frame error phenomenon, the design puts forward adding frame identification and packet preprocessing at the sending and synchronizing combination at the receiving end. For the solution of scheduling problem, the wireless communication channel cooperative work and video data transmission scheduling management algorithm is proposed in the design.

Bit Error Rate Performance of a MIMO-CDMA System Employing Parity-Bit-Selected Spreading in Frequency Nonselective Rayleigh Fading

Directory of Open Access Journals (Sweden)

Claude D'Amours

2011-01-01

Full Text Available We analytically derive the upper bound for the bit error rate (BER performance of a single user multiple input multiple output code division multiple access (MIMO-CDMA system employing parity-bit-selected spreading in slowly varying, flat Rayleigh fading. The analysis is done for spatially uncorrelated links. The analysis presented demonstrates that parity-bit-selected spreading provides an asymptotic gain of 10log(Nt dB over conventional MIMO-CDMA when the receiver has perfect channel estimates. This analytical result concurs with previous works where the (BER is determined by simulation methods and provides insight into why the different techniques provide improvement over conventional MIMO-CDMA systems.

Invisible Bridges: Wireless Technology Links Minds over Space and Time

Science.gov (United States)

Lambert, Lori

2004-01-01

Eight years after Chief Sitting Bull, prophetic chief of the Great Sioux Nation, was assassinated in 1890, Guglielmo Marconi transmitted the first wireless telegraph signals across the Atlantic to England. Although these two events seem unrelated, the names of these two men of vision are linked together today by Marconi's wireless invention. Data,…

Adaptive digital beamforming for a CDMA mobile communications payload

Science.gov (United States)

Munoz-Garcia, Samuel G.; Ruiz, Javier Benedicto

1993-01-01

In recent years, Spread-Spectrum Code Division Multiple Access (CDMA) has become a very popular access scheme for mobile communications due to a variety of reasons: excellent performance in multipath environments, high scope for frequency reuse, graceful degradation near saturation, etc. In this way, a CDMA system can support simultaneous digital communication among a large community of relatively uncoordinated users sharing a given frequency band. Nevertheless, there are also important problems associated with the use of CDMA. First, in a conventional CDMA scheme, the signature sequences of asynchronous users are not orthogonal and, as the number of active users increases, the self-noise generated by the mutual interference between users considerably degrades the performance, particularly in the return link. Furthermore, when there is a large disparity in received powers - due to differences in slant range or atmospheric attenuation - the non-zero cross-correlation between the signals gives rise to the so-called near-far problem. This leads to an inefficient utilization of the satellite resources and, consequently, to a drastic reduction in capacity. Several techniques were proposed to overcome this problem, such as Synchronized CDMA - in which the signature sequences of the different users are quasi-orthogonal - and power control. At the expense of increased network complexity and user coordination, these techniques enable the system capacity to be restored by equitably sharing the satellite resources among the users. An alternative solution is presented based upon the use of time-reference adaptive digital beamforming on board the satellite. This technique enables a high number of independently steered beams to be generated from a single phased array antenna, which automatically track the desired user signal and null the unwanted interference source. In order to use a time-reference adaptive antenna in a communications system, the main challenge is to obtain a

Performance of Generalized Multicarrier DS-CDMA over Nakagami-$m$ Fading Channels

OpenAIRE

Yang, L-L.; Hanzo, L.

2002-01-01

A class of generalized multicarrier direct sequence code-division multiple-access (MC DS-CDMA) schemes is defined and its performance is considered over multipath Nakagamifading channels. The spacing between two adjacent subcarriers of the generalized MC DS-CDMA is a variable, allowing us to gain insight into the effects of the spacing on the bit error rate (BER) performance of MC DS-CDMA systems. This generalized MC DS-CDMA scheme includes the subclasses of multitone DS-CDMA and orthogonal M...

Performance Analysis of Polarization Modulated DirectDetection Optical CDMA Systems over Turbulent FSO LinksModeled by the Gamma-Gamma Distribution

Directory of Open Access Journals (Sweden)

Fan Bai

2015-01-01

Full Text Available This paper proposes a theoretical study to characterize the transmission of optical code division multiple access (CDMA systems deploying polarization shift keying (PolSK over a free space optical (FSO link under the impact of atmospheric turbulence. In our analysis, a novel transceiver architecture for atmospheric OCDMA FSO systems based on polarization modulation with direct detection is proposed and discussed. A detailed analytical model for PolSK-OCDMA systems over a turbulent FSO link is provided. Further, we derive a closed-form bit error ratio (BER and outage probability expressions, taking into account the multiple-access interference (MAI, optical noise and the atmospheric turbulence effect on the FSO link modeled by the Gamma-Gamma distribution. Finally, the results of this study show the most significant parameters that degrade the transmission performance of the PolSK-OCDMA signal over FSO links and indicate that the proposed approach offers improved bit error ratio (BER performances compared to the on-off-keying (OOK modulation scheme in the presence of turbulence.

Robust optical wireless links over turbulent media using diversity solutions

Science.gov (United States)

Moradi, Hassan

Free-space optic (FSO) technology, i.e., optical wireless communication (OWC), is widely recognized as superior to radio frequency (RF) in many aspects. Visible and invisible optical wireless links solve first/last mile connectivity problems and provide secure, jam-free communication. FSO is license-free and delivers high-speed data rates in the order of Gigabits. Its advantages have fostered significant research efforts aimed at utilizing optical wireless communication, e.g. visible light communication (VLC), for high-speed, secure, indoor communication under the IEEE 802.15.7 standard. However, conventional optical wireless links demand precise optical alignment and suffer from atmospheric turbulence. When compared with RF, they suffer a low degree of reliability and lack robustness. Pointing errors cause optical transceiver misalignment, adversely affecting system reliability. Furthermore, atmospheric turbulence causes irradiance fluctuations and beam broadening of transmitted light. Innovative solutions to overcome limitations on the exploitation of high-speed optical wireless links are greatly needed. Spatial diversity is known to improve RF wireless communication systems. Similar diversity approaches can be adapted for FSO systems to improve its reliability and robustness; however, careful diversity design is needed since FSO apertures typically remain unbalanced as a result of FSO system sensitivity to misalignment. Conventional diversity combining schemes require persistent aperture monitoring and repetitive switching, thus increasing FSO implementation complexities. Furthermore, current RF diversity combining schemes may not be optimized to address the issue of unbalanced FSO receiving apertures. This dissertation investigates two efficient diversity combining schemes for multi-receiving FSO systems: switched diversity combining and generalized selection combining. Both can be exploited to reduce complexity and improve combining efficiency. Unlike maximum

Wireless Phone Threat Assessment for Aircraft Communication and Navigation Radios

Science.gov (United States)

Nguyens, T. X.; Koppen, S. V.; Smith, L. J.; Williams, R. A.; Salud, M. T.

2005-01-01

Emissions in aircraft communication and navigation bands are measured for the latest generation of wireless phones. The two wireless technologies considered, GSM/GPRS and CDMA2000, are the latest available to general consumers in the U.S. A base-station simulator is used to control the phones. The measurements are conducted using reverberation chambers, and the results are compared against FCC and aircraft installed equipment emission limits. The results are also compared against baseline emissions from laptop computers and personal digital assistant devices that are currently allowed to operate on aircraft.

Sharing possibilities amongst CDMA Mobile Satellite Systems, and impacts of terminal characteristics on sharing

Science.gov (United States)

Bambace, Luís Antonio Waack; Ceballos, Décio Castilho

CDMA Mobile Satellite Systems (CDMA MSS) are able to co-directional, co-frequency and co-coverage sharing, and they are strongly interdependent in case of such a sharing. It is also known that the success of any telecommunication project is the use of the correct media to each task. Operators have a clear sight of such a media adequacy in traditional systems, but not necessarily in the case of Mobile Satellite Systems. This creates a risk that a wrong market objective operator causes trouble to other systems. This paper deals with the sharing alternatives for up to four CDMA MSS operating in the same frequency band, and analysts both: satellite to user downlink and user to satellite uplink. The influence of several items in capacity is here treated. The scope includes: downlink power flux density: code availability; single system internal interference; inter-system interference; diversity schemes: average link impairments, margins; user cooperation; terminal specifications and the dependence of the insulation between RHCP and LHCP with fade.

IO-Link Wireless enhanced factory automation communication for Industry 4.0 applications

Directory of Open Access Journals (Sweden)

R. Heynicke

2018-03-01

Full Text Available In the context of the Industry 4.0 initiative, Cyber-Physical Production Systems (CPPS or Cyber Manufacturing Systems (CMS can be characterized as advanced networked mechatronic production systems gaining their added value by interaction with the ambient Industrial Internet of Things (IIoT. In this context appropriate communication technologies and standards play a vital role to realize the manifold potential improvements in the production process. One of these standards is IO-Link. In 2016 more than 5 million IO-Link nodes have been produced and delivered, still gaining increasing acceptance for the communication between sensors, actuators and the control level. The steadily increasing demand for more flexibility in automation solutions can be fulfilled using wireless technologies. With the wireless extension for the IO-Link standard, which will be presented in this article, maximum cycle times of 5 ms can be achieved with a probability that this limit will be exceeded to be at maximum one part per billion. Also roaming capabilities, wireless coexistence mechanisms and the possibility to include battery-powered or energy-harvesting sensors with very limited energy resources in the realtime network were defined. For system planning, setup, operation and maintenance, the standard engineering tools of IO-Link can be employed so that the backward compatibility with wired IO-Link solutions can be guaranteed. Interoperability between manufacturers is a key requirement for any communication standard, thus a procedure for IO-Link Wireless testing is also suggested.

Deflating link buffers in a wireless mesh network

KAUST Repository

Jamshaid, Kamran; Shihada, Basem; Showail, Ahmad; Levis, Philip

2014-01-01

We analyze the problem of buffer sizing for backlogged TCP flows in 802.11-based wireless mesh networks. Our objective is to maintain high network utilization while providing low queueing delays. Unlike wired networks where a single link buffer feeds a bottleneck link, the radio spectral resource in a mesh network is shared among a set of contending mesh routers. We account for this by formulating the buffer size problem as sizing a collective buffer distributed over a set of interfering nodes. In this paper we propose mechanisms for sizing and distributing this collective buffer among the mesh nodes constituting the network bottleneck. Our mechanism factors in the network topology and wireless link rates, improving on pre-set buffer allocations that cannot optimally work across the range of configurations achievable with 802.11 radios. We evaluate our mechanisms using simulations as well as experiments on a testbed. Our results show that we can reduce the RTT of a flow by 6× or more, at the cost of less than 10% drop in end-to-end flow throughput.

Deflating link buffers in a wireless mesh network

KAUST Repository

Jamshaid, Kamran

2014-05-01

We analyze the problem of buffer sizing for backlogged TCP flows in 802.11-based wireless mesh networks. Our objective is to maintain high network utilization while providing low queueing delays. Unlike wired networks where a single link buffer feeds a bottleneck link, the radio spectral resource in a mesh network is shared among a set of contending mesh routers. We account for this by formulating the buffer size problem as sizing a collective buffer distributed over a set of interfering nodes. In this paper we propose mechanisms for sizing and distributing this collective buffer among the mesh nodes constituting the network bottleneck. Our mechanism factors in the network topology and wireless link rates, improving on pre-set buffer allocations that cannot optimally work across the range of configurations achievable with 802.11 radios. We evaluate our mechanisms using simulations as well as experiments on a testbed. Our results show that we can reduce the RTT of a flow by 6× or more, at the cost of less than 10% drop in end-to-end flow throughput.

Design of a search and rescue terminal based on the dual-mode satellite and CDMA network

Science.gov (United States)

Zhao, Junping; Zhang, Xuan; Zheng, Bing; Zhou, Yubin; Song, Hao; Song, Wei; Zhang, Meikui; Liu, Tongze; Zhou, Li

2010-12-01

The current goal is to create a set of portable terminals with GPS/BD2 dual-mode satellite positioning, vital signs monitoring and wireless transmission functions. The terminal depends on an ARM processor to collect and combine data related to vital signs and GPS/BD2 location information, and sends the message to headquarters through the military CDMA network. It integrates multiple functions as a whole. The satellite positioning and wireless transmission capabilities are integrated into the motherboard, and the vital signs sensors used in the form of belts communicate with the board through Bluetooth. It can be adjusted according to the headquarters' instructions. This kind of device is of great practical significance for operations during disaster relief, search and rescue of the wounded in wartime, non-war military operations and other special circumstances.

Link and route availability for Inter-working multi-hop wireless networks

CSIR Research Space (South Africa)

Salami, O

2009-09-01

Full Text Available pairs in inter-working multi-hop wireless networks can be evaluated based on the availability and reliability of radio links that form the communication path linking the nodes. This paper presents an analytical study of the link and route availability...

Wireless Cellular Mobile Communications

Directory of Open Access Journals (Sweden)

V. Zalud

2002-12-01

Full Text Available In this article is briefly reviewed the history of wireless cellularmobile communications, examined the progress in current secondgeneration (2G cellular standards and discussed their migration to thethird generation (3G. The European 2G cellular standard GSM and itsevolution phases GPRS and EDGE are described somewhat in detail. Thethird generation standard UMTS taking up on GSM/GPRS core network andequipped with a new advanced access network on the basis of codedivision multiple access (CDMA is investigated too. A sketch of theperspective of mobile communication beyond 3G concludes this article.

Link Adaptation for Framed Multimedia Data Transmission over a DS-CDMA Communication System

Directory of Open Access Journals (Sweden)

David Declercq

2005-02-01

Full Text Available In the context of frame-based multimedia wireless transmission, a link adaptation strategy is proposed, assuming that the source decoder may accept some remaining errors at the output of the channel decoder. Based on a target mean bit error rate for erroneous frames, a minimum bit-energy-to-equivalent-noise ratio is chosen. Under this constraint, a new link adaptation criterion is proposed: the maximization of the minimum user's information rate through dynamic spreading gain and power control, allowing to guarantee a transmission for each and every user. An analytical solution to this constrained optimization problem is proposed and its performance is studied in a Rayleigh-fading environment.

Effect of Interleaved FEC Code on Wavelet Based MC-CDMA System with Alamouti STBC in Different Modulation Schemes

OpenAIRE

Shams, Rifat Ara; Kabir, M. Hasnat; Ullah, Sheikh Enayet

2012-01-01

In this paper, the impact of Forward Error Correction (FEC) code namely Trellis code with interleaver on the performance of wavelet based MC-CDMA wireless communication system with the implementation of Alamouti antenna diversity scheme has been investigated in terms of Bit Error Rate (BER) as a function of Signal-to-Noise Ratio (SNR) per bit. Simulation of the system under proposed study has been done in M-ary modulation schemes (MPSK, MQAM and DPSK) over AWGN and Rayleigh fading channel inc...

Microwave Photonics Techniques Supporting Flexible Wireless Communications Links

DEFF Research Database (Denmark)

Rommel, Simon; Cavalcante, Lucas Costa Pereira; Vegas Olmos, Juan José

Wireless data communication links supporting the next generation 5G and beyond mobile networking face a set of engineering challenges related to the mandatory operation at mmw and higher frequency bands, provide capacities above 10 Gb/s, satisfy latency, robustness, flexibility and low complexity...

An Inductive Link-Based Wireless Power Transfer System for Biomedical Applications

Directory of Open Access Journals (Sweden)

M. A. Adeeb

2012-01-01

Full Text Available A wireless power transfer system using an inductive link has been demonstrated for implantable sensor applications. The system is composed of two primary blocks: an inductive power transfer unit and a backward data communication unit. The inductive link performs two functions: coupling the required power from a wireless power supply system enabling battery-less, long-term implant operation and providing a backward data transmission path. The backward data communication unit transmits the data to an outside reader using FSK modulation scheme via the inductive link. To demonstrate the operation of the inductive link, a board-level design has been implemented with high link efficiency. Test results from a fabricated sensor system, composed of a hybrid implementation of custom-integrated circuits and board-level discrete components, are presented demonstrating power transmission of 125 mW with a 12.5% power link transmission efficiency. Simultaneous backward data communication involving a digital pulse rate of up to 10 kbps was also observed.

Millimeter Wave Hybrid Photonic Wireless Links for High-Speed Wireless Access and Mobile Fronthaul

DEFF Research Database (Denmark)

Rommel, Simon

As the introduction of the fifth generation of mobile services (5G) is set to revolutionize the way people, devices and machines connect, the changes to the underlying networks and technologies are no less drastic. The massive increase in user and data capacity, as well as the decrease in latency...... networks. In summary, the work presented in this thesis has regarded a multitude of aspects of millimeter wave hybrid photonic wireless links, expanding upon the state of the art and showing their feasibility for use in fifth generation mobile and high speed wireless access networks – hopefully bringing...

Impact of Various Parameters on the Performance of Inter-aircraft Optical Wireless Communication Link

Science.gov (United States)

Singh, Mehtab

2017-12-01

Optical wireless communication (OWC) systems also known as Free space optics (FSO) are capable of providing high channel bandwidth, high data transmission rates, low power consumption, and high security. OWC links are being considered in different applications such as inter-satellite links, terrestrial links, and inter-aircraft communication links. This paper investigates the impact of different system parameters such as transmission power level, operating wavelength, transmitter pointing error angle, bit transmission rate, atmospheric attenuation, antenna aperture diameter, geometric losses, the responsivity of the photodetector, and link range on the performance of inter-aircraft optical wireless communication link.

Asynchronous, Decentralized DS-CDMA Using Feedback-Controlled Spreading Sequences for Time-Dispersive Channels

Science.gov (United States)

Miyatake, Teruhiko; Chiba, Kazuki; Hamamura, Masanori; Tachikawa, Shin'ichi

We propose a novel asynchronous direct-sequence codedivision multiple access (DS-CDMA) using feedback-controlled spreading sequences (FCSSs) (FCSS/DS-CDMA). At the receiver of FCSS/DS-CDMA, the code-orthogonalizing filter (COF) produces a spreading sequence, and the receiver returns the spreading sequence to the transmitter. Then the transmitter uses the spreading sequence as its updated version. The performance of FCSS/DS-CDMA is evaluated over time-dispersive channels. The results indicate that FCSS/DS-CDMA greatly suppresses both the intersymbol interference (ISI) and multiple access interference (MAI) over time-invariant channels. FCSS/DS-CDMA is applicable to the decentralized multiple access.

Optical CDMA and WDMA in the access network

Science.gov (United States)

Sargent, Edward H.; Stok, Andrew

2003-08-01

Optical CDMA provides one avenue to sharing the vast bandwidth of optical fiber among a number of active users in a network. In this work we address two questions central to considering the areas of applicability of CDMA in optics: (1) How do we compare fairly optical CDMA codes of different families, and what do we conclude? (2) How do we compare optical CDMA performance with that of conventional optical WDMA? To answer the first question, we present a method of comparing optical CDMA codes of different families, sizes and weights. We outline why the traditional performance metric of bit-error rate versus number of simultaneous users is lacking and propose a different performance measure -- the peak throughput normalized with respect to the size of the code. This metric is used to show that optical-orthogonal codes (OOCs) with a weight of 4 perform best at low offered loads while OOCs with weight 5 should be used at higher offered loads. By applying the technique across different families of codes, we demonstrate that multi-wavelength OOCs (MWOOCs) perform better than both OOCs (by a factor of approximately 1.25) and asymmetric prime-hop codes (by a factor of approximately 3.5), over a wide range of offered loads. In answer to the second question, we present a comparison of the performance of optical code-division multiple-access (CDMA) systems with that of a wavelength-division multiple-access (WDMA) system. The multiple-access techniques are applied in a time-slotted broadcast local-area network. The utilization, defined as the throughput per unit of time-domain bandwidth expansion, and packet delay are used as metrics of performance. When more than seven wavelengths are available, optical CDMA systems using asymmetric prime-hop codes and all-optical signal processing are shown to have higher peak utilization and lower corresponding delay than a WDMA system with the same number of wavelengths. When the encoders/decoders operate at the chip rate, the utilization

Efficient Smart Antenna Systems (4G) For CDMA Wireless Communication

OpenAIRE

Singla, Brahm Mohinder; Kumar, Ashish

2012-01-01

Today, mobile communications play a central role in the voice/data network arena. With the deployment of mass scale 3G just around the corner, new directions are already being researched. In this paper we address about the 4TH G mobile communications.The Fourth Generation (4G) Mobile Communications should not focus only on the data-rate increase and new air interface.4G Mobile should instead con-verge the advanced wireless mobile communications and high-speed wireless access systems into an O...

Optical wireless links with enhanced linearity and selectivity [Invited

Science.gov (United States)

Green, Roger J.; Sweet, C.; Idrus, S.

2005-10-01

Optical wireless is an attractive medium as an alternative to optical fiber communications, and also to RF, because of its high bandwidth and relative ease of use, especially when it comes to deployment in new physical situations. We describe an optical wireless link approach that offers a performance that gives analog transmission with significantly reduced distortion levels and enhanced reception sensitivity by combining a novel hybrid detector-amplifier technique. Reduction of distortion by 40 dB and improvement in sensitivity of 20-30 dB is possible, using the techniques described.

A Unified Approach to the Analysis of Multicarrier DS-CDMA over Nakagami-$M$ Fading Channels

OpenAIRE

Yang, L-L.; Hanzo, L.

2001-01-01

A class of unified multicarrier DS-CDMA (MC DS-CDMA) schemes is defined and its performance is considered over multipath Nakagami-$M$ fading channels. The spacing between two adjacent subcarriers of the unified MC DS-CDMA scheme is a variable, allowing us to gain insight into the effects of the spacing on the bit error rate (BER) performance of MC DS-CDMA systems. This unified MC DS-CDMA scheme includes the subclasses of multitone DS-CDMA and orthogonal MC DS-CDMA as special cases. The optimu...

28 GHz Wireless Backhaul Transceiver Characterization and Radio Link Budget

Directory of Open Access Journals (Sweden)

Marko E. Leinonen

2018-02-01

Full Text Available Millimeter wave communication is one of the main disruptive technologies in upcoming 5G mobile networks. One of the first candidate applications, which will be commercially ready by 2020, is wireless backhaul links or wireless last mile communication. This paper provides an analysis of this use‐case from radio engineering and implementation perspectives. Furthermore, preliminary experimental results are shown for a proof‐of‐concept wireless backhaul solution developed within the EU‐KR 5GCHAMPION project, which will be showcased during the 2018 Winter Olympic Games in Korea. In this paper, we verify system level calculations and a theoretical link budget analysis with conductive and radiated over‐the‐air measurements. The results indicate that the implemented radio solution is able to achieve the target key performance indicator, namely, a 2.5 Gbps data rate on average, over a range of up to 200 m.

Automatic Loss Adjustment for CDMA2000 and 1xEV-DO Standard for Downlink and Uplink

Directory of Open Access Journals (Sweden)

Jiri Kominek

2014-01-01

Full Text Available The functional and thermal testing of the mobile phone is always performed under various conditions that vary in terms of the connection between the DUT (Device Under Test and the measuring instrument. To achieve repeatable measurements under such conditions, it is necessary to adjust uplink and downlink loss using the instrument's external attenuation. While for GSM, WCDMA and LTE this is a relatively easy task, CDMA2000 and 1xEV-DO make automation of the adjustment process somewhat challenging due to the nature of the CDMA standard. An especially forward link is more complicated as those tests are run in signaling mode and not all instruments provide an FER value measured by an MS. This paper describes the algorithm for forward link loss adjustment and its implementation using Rohde & Schwarz CMW500.

Spreading Sequence Design and Theoretical Limits for Quasisynchronous CDMA Systems

Directory of Open Access Journals (Sweden)

Fan Pingzhi

2004-01-01

Full Text Available For various quasisynchronous (QS CDMA systems such as LAS-CDMA system which emerged recently, in order to reduce or eliminate the multiple access interference and multipath interference, it is required to design a set of spreading sequences which are mutually orthogonal within a designed shift zone, called orthogonal zone. For traditional orthogonal sequences, such as Walsh sequences and orthogonal Gold sequences, the orthogonality can only be achieved at the inphase point; in other words, the orthogonality is destroyed whenever there is a relative shift between the sequences, that is, their orthogonal zone is 0. In this paper, new concepts of generalized orthogonality (GO and generalized quasiorthogonality (GQO for spreading sequence design in both direct sequence (DS QS-CDMA systems and time/frequency hopping (TH/FH QS-CDMA systems are presented. Besides, selected GO/GQO sequence designs and general theoretical periodic and aperiodic limits, together with several applications in QS-CDMA systems, are also reviewed and analyzed.

Link-quality measurement and reporting in wireless sensor networks.

Science.gov (United States)

Chehri, Abdellah; Jeon, Gwanggil; Choi, Byoungjo

2013-03-04

Wireless Sensor networks (WSNs) are created by small hardware devices that possess the necessary functionalities to measure and exchange a variety of environmental data in their deployment setting. In this paper, we discuss the experiments in deploying a testbed as a first step towards creating a fully functional heterogeneous wireless network-based underground monitoring system. The system is mainly composed of mobile and static ZigBee nodes, which are deployed on the underground mine galleries for measuring ambient temperature. In addition, we describe the measured results of link characteristics such as received signal strength, latency and throughput for different scenarios.

Link-Quality Measurement and Reporting in Wireless Sensor Networks

Directory of Open Access Journals (Sweden)

Byoungjo Choi

2013-03-01

Full Text Available Wireless Sensor networks (WSNs are created by small hardware devices that possess the necessary functionalities to measure and exchange a variety of environmental data in their deployment setting. In this paper, we discuss the experiments in deploying a testbed as a first step towards creating a fully functional heterogeneous wireless network-based underground monitoring system. The system is mainly composed of mobile and static ZigBee nodes, which are deployed on the underground mine galleries for measuring ambient temperature. In addition, we describe the measured results of link characteristics such as received signal strength, latency and throughput for different scenarios.

Dynamic Resource Management in MC-CDMA Based Cellular Wireless Networks

Directory of Open Access Journals (Sweden)

Bala Jeevitha Vani

2009-10-01

Full Text Available Most of the multimedia and Internet services today are asymmetric in nature, and require high data rate support. Allocating equal band width in both uplink and downlink is not prudent solution, as most of the time user requirement is more either in uplink or downlink. The Multi Carrier Code Division Multiple Access (MC-CDMA system with time division duplex mode can easily met this requirement by dynamically declaring traffic direction in TDD slot, and adaptively allocating the sub channels. In this paper, we propose a adaptive slot and sub carrier allocation algorithm, that can be independently implemented in each cell of mobile communication network. Our analytical model is generalization of two cell concept to represent a multi cell model. Based on two cell concept four cases of interference pattern has been considered and simulated separately in presence of Additive White Gaussian Noise (AWGN and Rayleigh Channel. The simulated result suggests the requirement of approximately 9dB of Signal to Noise Ratio (SNR to maintain Bit Error Rate below 10-3. We also analyze the average delay incurred by the proposed algorithm in allocating resources.

Low complexity source and channel coding for mm-wave hybrid fiber-wireless links

DEFF Research Database (Denmark)

Lebedev, Alexander; Vegas Olmos, Juan José; Pang, Xiaodan

2014-01-01

We report on the performance of channel and source coding applied for an experimentally realized hybrid fiber-wireless W-band link. Error control coding performance is presented for a wireless propagation distance of 3 m and 20 km fiber transmission. We report on peak signal-to-noise ratio perfor...

Single integrated device for optical CDMA code processing in dual-code environment.

Science.gov (United States)

Huang, Yue-Kai; Glesk, Ivan; Greiner, Christoph M; Iazkov, Dmitri; Mossberg, Thomas W; Wang, Ting; Prucnal, Paul R

2007-06-11

We report on the design, fabrication and performance of a matching integrated optical CDMA encoder-decoder pair based on holographic Bragg reflector technology. Simultaneous encoding/decoding operation of two multiple wavelength-hopping time-spreading codes was successfully demonstrated and shown to support two error-free OCDMA links at OC-24. A double-pass scheme was employed in the devices to enable the use of longer code length.

Minimizing SIP Session Re-Setup Delay over Wireless Link in 3G Handover Scenarios

Directory of Open Access Journals (Sweden)

Moon Bongkyo

2010-01-01

Full Text Available The delay in transmitting SIP messages over the wireless link for session resetup at handover is still major bottleneck for interactive multimedia service. In this paper, a proxy agent-based scheme is proposed to minimize the SIP session setup delay over a wireless link in 3G inter-subnet handover scenarios. This scheme is based on the two characteristics. One is that the major factor of SIP session re-setup delay is generally caused by the retransmissions in the unreliable wireless links, and the other is that most of the fields in request messages as well as response messages are duplicated when a set of SIP messages are exchanged during session re-setup procedure. In this scheme, no change is required in the SIP message processing except for the proxy agents in both BS and MH.

Demonstration of the CDMA-mode CAOS smart camera.

Science.gov (United States)

Riza, Nabeel A; Mazhar, Mohsin A

2017-12-11

Demonstrated is the code division multiple access (CDMA)-mode coded access optical sensor (CAOS) smart camera suited for bright target scenarios. Deploying a silicon CMOS sensor and a silicon point detector within a digital micro-mirror device (DMD)-based spatially isolating hybrid camera design, this smart imager first engages the DMD starring mode with a controlled factor of 200 high optical attenuation of the scene irradiance to provide a classic unsaturated CMOS sensor-based image for target intelligence gathering. Next, this CMOS sensor provided image data is used to acquire a focused zone more robust un-attenuated true target image using the time-modulated CDMA-mode of the CAOS camera. Using four different bright light test target scenes, successfully demonstrated is a proof-of-concept visible band CAOS smart camera operating in the CDMA-mode using up-to 4096 bits length Walsh design CAOS pixel codes with a maximum 10 KHz code bit rate giving a 0.4096 seconds CAOS frame acquisition time. A 16-bit analog-to-digital converter (ADC) with time domain correlation digital signal processing (DSP) generates the CDMA-mode images with a 3600 CAOS pixel count and a best spatial resolution of one micro-mirror square pixel size of 13.68 μm side. The CDMA-mode of the CAOS smart camera is suited for applications where robust high dynamic range (DR) imaging is needed for un-attenuated un-spoiled bright light spectrally diverse targets.

Design and performance analysis for several new classes of codes for optical synchronous CDMA and for arbitrary-medium time-hopping synchronous CDMA communication systems

Science.gov (United States)

Kostic, Zoran; Titlebaum, Edward L.

1994-08-01

New families of spread-spectrum codes are constructed, that are applicable to optical synchronous code-division multiple-access (CDMA) communications as well as to arbitrary-medium time-hopping synchronous CDMA communications. Proposed constructions are based on the mappings from integer sequences into binary sequences. We use the concept of number theoretic quadratic congruences and a subset of Reed-Solomon codes similar to the one utilized in the Welch-Costas frequency-hop (FH) patterns. The properties of the codes are as good as or better than the properties of existing codes for synchronous CDMA communications: Both the number of code-sequences within a single code family and the number of code families with good properties are significantly increased when compared to the known code designs. Possible applications are presented. To evaluate the performance of the proposed codes, a new class of hit arrays called cyclical hit arrays is recalled, which give insight into the previously unknown properties of the few classes of number theoretic FH patterns. Cyclical hit arrays and the proposed mappings are used to determine the exact probability distribution functions of random variables that represent interference between users of a time-hopping or optical CDMA system. Expressions for the bit error probability in multi-user CDMA systems are derived as a function of the number of simultaneous CDMA system users, the length of signature sequences and the threshold of a matched filter detector. The performance results are compared with the results for some previously known codes.

Handoff Triggering and Network Selection Algorithms for Load-Balancing Handoff in CDMA-WLAN Integrated Networks

Directory of Open Access Journals (Sweden)

Khalid Qaraqe

2008-10-01

Full Text Available This paper proposes a novel vertical handoff algorithm between WLAN and CDMA networks to enable the integration of these networks. The proposed vertical handoff algorithm assumes a handoff decision process (handoff triggering and network selection. The handoff trigger is decided based on the received signal strength (RSS. To reduce the likelihood of unnecessary false handoffs, the distance criterion is also considered. As a network selection mechanism, based on the wireless channel assignment algorithm, this paper proposes a context-based network selection algorithm and the corresponding communication algorithms between WLAN and CDMA networks. This paper focuses on a handoff triggering criterion which uses both the RSS and distance information, and a network selection method which uses context information such as the dropping probability, blocking probability, GoS (grade of service, and number of handoff attempts. As a decision making criterion, the velocity threshold is determined to optimize the system performance. The optimal velocity threshold is adjusted to assign the available channels to the mobile stations. The optimal velocity threshold is adjusted to assign the available channels to the mobile stations using four handoff strategies. The four handoff strategies are evaluated and compared with each other in terms of GOS. Finally, the proposed scheme is validated by computer simulations.

Handoff Triggering and Network Selection Algorithms for Load-Balancing Handoff in CDMA-WLAN Integrated Networks

Directory of Open Access Journals (Sweden)

Kim Jang-Sub

2008-01-01

Full Text Available This paper proposes a novel vertical handoff algorithm between WLAN and CDMA networks to enable the integration of these networks. The proposed vertical handoff algorithm assumes a handoff decision process (handoff triggering and network selection. The handoff trigger is decided based on the received signal strength (RSS. To reduce the likelihood of unnecessary false handoffs, the distance criterion is also considered. As a network selection mechanism, based on the wireless channel assignment algorithm, this paper proposes a context-based network selection algorithm and the corresponding communication algorithms between WLAN and CDMA networks. This paper focuses on a handoff triggering criterion which uses both the RSS and distance information, and a network selection method which uses context information such as the dropping probability, blocking probability, GoS (grade of service, and number of handoff attempts. As a decision making criterion, the velocity threshold is determined to optimize the system performance. The optimal velocity threshold is adjusted to assign the available channels to the mobile stations. The optimal velocity threshold is adjusted to assign the available channels to the mobile stations using four handoff strategies. The four handoff strategies are evaluated and compared with each other in terms of GOS. Finally, the proposed scheme is validated by computer simulations.

Optical wireless link between a nanoscale antenna and a transducing rectenna.

Science.gov (United States)

Dasgupta, Arindam; Mennemanteuil, Marie-Maxime; Buret, Mickaël; Cazier, Nicolas; Colas-des-Francs, Gérard; Bouhelier, Alexandre

2018-05-18

Initiated as a cable-replacement solution, short-range wireless power transfer has rapidly become ubiquitous in the development of modern high-data throughput networking in centimeter to meter accessibility range. Wireless technology is now penetrating a higher level of system integration for chip-to-chip and on-chip radiofrequency interconnects. However, standard CMOS integrated millimeter-wave antennas have typical size commensurable with the operating wavelength, and are thus an unrealistic solution for downsizing transmitters and receivers to the micrometer and nanometer scale. Herein, we demonstrate a light-in and electrical signal-out, on-chip wireless near-infrared link between a 220 nm optical antenna and a sub-nanometer rectifying antenna converting the transmitted optical energy into direct electrical current. The co-integration of subwavelength optical functional devices with electronic transduction offers a disruptive solution to interface photons and electrons at the nanoscale for on-chip wireless optical interconnects.

Space-Time Coded MC-CDMA: Blind Channel Estimation, Identifiability, and Receiver Design

Directory of Open Access Journals (Sweden)

Li Hongbin

2002-01-01

Full Text Available Integrating the strengths of multicarrier (MC modulation and code division multiple access (CDMA, MC-CDMA systems are of great interest for future broadband transmissions. This paper considers the problem of channel identification and signal combining/detection schemes for MC-CDMA systems equipped with multiple transmit antennas and space-time (ST coding. In particular, a subspace based blind channel identification algorithm is presented. Identifiability conditions are examined and specified which guarantee unique and perfect (up to a scalar channel estimation when knowledge of the noise subspace is available. Several popular single-user based signal combining schemes, namely the maximum ratio combining (MRC and the equal gain combining (EGC, which are often utilized in conventional single-transmit-antenna based MC-CDMA systems, are extended to the current ST-coded MC-CDMA (STC-MC-CDMA system to perform joint combining and decoding. In addition, a linear multiuser minimum mean-squared error (MMSE detection scheme is also presented, which is shown to outperform the MRC and EGC at some increased computational complexity. Numerical examples are presented to evaluate and compare the proposed channel identification and signal detection/combining techniques.

Physical Layer Built-In Security Analysis and Enhancement Algorithms for CDMA Systems

Directory of Open Access Journals (Sweden)

Li Tongtong

2007-01-01

Full Text Available Historically developed for secure communication and military use, CDMA has been identified as a major modulation and multiple-access technique for 3G systems and beyond. In addition to the wide bandwidth and low power-spectrum density which make CDMA signals robust to narrowband jamming and easy to be concealed within the noise floor, the physical layer built-in information privacy of CDMA system is provided by pseudorandom scrambling. In this paper, first, security weakness of the operational and proposed CDMA airlink interfaces is analyzed. Second, based on the advanced encryption standard (AES, we propose to enhance the physical layer built-in security of CDMA systems through secure scrambling. Performance analysis demonstrates that while providing significantly improved information privacy, CDMA systems with secure scrambling have comparable computational complexity and overall system performance with that of conventionally scrambled systems. Moreover, it is shown that by scrambling the training sequence and the message sequence separately with two independent scrambling sequences, both information privacy and system performance can be further improved. The proposed scheme can readily be applied to 3G systems and beyond.

Bidirectional 3.125 Gbps downstream / 2 Gbps upstream impulse radio ultrawide-band (UWB) over combined fiber and wireless link

DEFF Research Database (Denmark)

Jensen, Jesper Bevensee; Gibbon, Timothy Braidwood; Yu, Xianbin

2010-01-01

We demonstrate bidirectional fiber and wireless transmission of impulse radio ultra-wideband at 3.125 Gbps downstream and 2 Gbps upstream. After transmission over 50 km fiber and 1.85 m wireless link both signals are recovered without errors.......We demonstrate bidirectional fiber and wireless transmission of impulse radio ultra-wideband at 3.125 Gbps downstream and 2 Gbps upstream. After transmission over 50 km fiber and 1.85 m wireless link both signals are recovered without errors....

Improved Iterative Parallel Interference Cancellation Receiver for Future Wireless DS-CDMA Systems

Directory of Open Access Journals (Sweden)

Andrea Bernacchioni

2005-04-01

Full Text Available We present a new turbo multiuser detector for turbo-coded direct sequence code division multiple access (DS-CDMA systems. The proposed detector is based on the utilization of a parallel interference cancellation (PIC and a bank of turbo decoders. The PIC is broken up in order to perform interference cancellation after each constituent decoder of the turbo decoding scheme. Moreover, in the paper we propose a new enhanced algorithm that provides a more accurate estimation of the signal-to-noise-plus-interference-ratio used in the tentative decision device and in the MAP decoding algorithm. The performance of the proposed receiver is evaluated by means of computer simulations for medium to very high system loads, in AWGN and multipath fading channel, and compared to recently proposed interference cancellation-based iterative MUD, by taking into account the number of iterations and the complexity involved. We will see that the proposed receiver outperforms the others especially for highly loaded systems.

Theoretical analysis and simulation of a code division multiple access system (cdma for secure signal transmission in wideband channels

Directory of Open Access Journals (Sweden)

Stevan M. Berber

2014-06-01

Full Text Available Chaotic spreading sequences can increase secrecy and resistance to interception in signal transmission. Chaos-based CDMA systems have been well investigated in the case of flat fading and noise presence in the channel. However, these systems operating in wideband channels, characterized by the frequency selective fading and white Gaussian noise, have not been investigated to the level of understanding their practical applications. This paper presents a detailed mathematical model of a CDMA system based on chaotic spreading sequences. In a theoretical analysis, all signals are represented in the discrete time domain. Using the theory of discrete time stochastic processes, the probability of error expressions are derived in a closed form for a multi-user chaos based CDMA system. For the sake of comparison, the expressions for the probability of error are derived separately for narrowband and wideband channels. The application of the system interleaving technique is investigated in particular, which showed that this technique can substantially improve probability of error in the system.  The system is simulated and the findings of the simulation confirmed theoretically expected results. Possible improvements in the probability of bit error due to multipath channel nature, with and without interleavers, are quantified depending on the random delay and the number of users in the system. In the analyzed system, a simplified version of the wideband channel model, proposed for modern wideband wireless networks, is used. Introduction Over the past years, the demand for wireless communications has increased substantially due to advancements in mobile communication systems and networks. Following these increasing demands, modern communication systems require the ability to handle a large number of users to process and transmit wideband signals through complex frequency selective channels. One of the techniques for transmission of multi-user signals is the

Multicarrier Block-Spread CDMA for Broadband Cellular Downlink

Directory of Open Access Journals (Sweden)

Leus Geert

2004-01-01

Full Text Available Effective suppression of multiuser interference (MUI and mitigation of frequency-selective fading effects within the complexity constraints of the mobile constitute major challenges for broadband cellular downlink transceiver design. Existing wideband direct-sequence (DS code division multiple access (CDMA transceivers suppress MUI statistically by restoring the orthogonality among users at the receiver. However, they call for receive diversity and multichannel equalization to improve the fading effects caused by deep channel fades. Relying on redundant block spreading and linear precoding, we design a so-called multicarrier block-spread- (MCBS-CDMA transceiver that preserves the orthogonality among users and guarantees symbol detection, regardless of the underlying frequency-selective fading channels. These properties allow for deterministic MUI elimination through low-complexity block despreading and enable full diversity gains, irrespective of the system load. Different options to perform equalization and decoding, either jointly or separately, strike the trade-off between performance and complexity. To improve the performance over multi-input multi-output (MIMO multipath fading channels, our MCBS-CDMA transceiver combines well with space-time block-coding (STBC techniques, to exploit both multiantenna and multipath diversity gains, irrespective of the system load. Simulation results demonstrate the superior performance of MCBS-CDMA compared to competing alternatives.

A Charrelation Matrix-Based Blind Adaptive Detector for DS-CDMA Systems

Directory of Open Access Journals (Sweden)

Zhongqiang Luo

2015-08-01

Full Text Available In this paper, a blind adaptive detector is proposed for blind separation of user signals and blind estimation of spreading sequences in DS-CDMA systems. The blind separation scheme exploits a charrelation matrix for simple computation and effective extraction of information from observation signal samples. The system model of DS-CDMA signals is modeled as a blind separation framework. The unknown user information and spreading sequence of DS-CDMA systems can be estimated only from the sampled observation signals. Theoretical analysis and simulation results show that the improved performance of the proposed algorithm in comparison with the existing conventional algorithms used in DS-CDMA systems. Especially, the proposed scheme is suitable for when the number of observation samples is less and the signal to noise ratio (SNR is low.

A Charrelation Matrix-Based Blind Adaptive Detector for DS-CDMA Systems.

Science.gov (United States)

Luo, Zhongqiang; Zhu, Lidong

2015-08-14

In this paper, a blind adaptive detector is proposed for blind separation of user signals and blind estimation of spreading sequences in DS-CDMA systems. The blind separation scheme exploits a charrelation matrix for simple computation and effective extraction of information from observation signal samples. The system model of DS-CDMA signals is modeled as a blind separation framework. The unknown user information and spreading sequence of DS-CDMA systems can be estimated only from the sampled observation signals. Theoretical analysis and simulation results show that the improved performance of the proposed algorithm in comparison with the existing conventional algorithms used in DS-CDMA systems. Especially, the proposed scheme is suitable for when the number of observation samples is less and the signal to noise ratio (SNR) is low.

Multichannel Baseband Processor for Wideband CDMA

Science.gov (United States)

Jalloul, Louay M. A.; Lin, Jim

2005-12-01

The system architecture of the cellular base station modem engine (CBME) is described. The CBME is a single-chip multichannel transceiver capable of processing and demodulating signals from multiple users simultaneously. It is optimized to process different classes of code-division multiple-access (CDMA) signals. The paper will show that through key functional system partitioning, tightly coupled small digital signal processing cores, and time-sliced reuse architecture, CBME is able to achieve a high degree of algorithmic flexibility while maintaining efficiency. The paper will also highlight the implementation and verification aspects of the CBME chip design. In this paper, wideband CDMA is used as an example to demonstrate the architecture concept.

Wireless link using on-chip photonic integrated millimeter-wave sources

NARCIS (Netherlands)

Guzmán, R. C.; Gordón, C.; Carpintero, G.; Leijtens, X.; Lawniczak, Katarzyna

2015-01-01

Over the last few years wireless link data traffic has drastically increased due to a change in the way today's society creates, shares, and consumes information. Millimeter-waves (30-300 GHz) have a great advantage due to the wide bandwidths available for carrying information, enabling broadband

Wireless Energy and Information Transmission in FSO and RF-FSO Links

KAUST Repository

Makki, Behrooz; Svensson, Tommy; Buisman, Koen; Perez, Joaquin; Alouini, Mohamed-Slim

2017-01-01

We propose and analyze a wireless energy and information transmission scheme in free-space optical (FSO) links. The results are presented for both quasi-static and fast-fading conditions. We derive closed-form expressions for throughput, outage

Full-duplex bidirectional transmission of 10-Gb/s millimeter-wave QPSK signal in E-band optical wireless link.

Science.gov (United States)

Fang, Yuan; Yu, Jianjun; Chi, Nan; Xiao, Jiangnan

2014-01-27

We experimentally demonstrated full-duplex bidirectional transmission of 10-Gb/s millimeter-wave (mm-wave) quadrature phase shift keying (QPSK) signal in E-band (71-76 GHz and 81-86 GHz) optical wireless link. Single-mode fibers (SMF) are connected at both sides of the antenna for uplink and downlink which realize 40-km SMF and 2-m wireless link for bidirectional transmission simultaneously. We utilized multi-level modulation format and coherent detection in such E-band optical wireless link for the first time. Mm-wave QPSK signal is generated by photonic technique to increase spectrum efficiency and received signal is coherently detected to improve receiver sensitivity. After the coherent detection, digital signal processing is utilized to compensate impairments of devices and transmission link.

Energy Efficient Link Aware Routing with Power Control in Wireless Ad Hoc Networks.

Science.gov (United States)

Katiravan, Jeevaa; Sylvia, D; Rao, D Srinivasa

2015-01-01

In wireless ad hoc networks, the traditional routing protocols make the route selection based on minimum distance between the nodes and the minimum number of hop counts. Most of the routing decisions do not consider the condition of the network such as link quality and residual energy of the nodes. Also, when a link failure occurs, a route discovery mechanism is initiated which incurs high routing overhead. If the broadcast nature and the spatial diversity of the wireless communication are utilized efficiently it becomes possible to achieve improvement in the performance of the wireless networks. In contrast to the traditional routing scheme which makes use of a predetermined route for packet transmission, such an opportunistic routing scheme defines a predefined forwarding candidate list formed by using single network metrics. In this paper, a protocol is proposed which uses multiple metrics such as residual energy and link quality for route selection and also includes a monitoring mechanism which initiates a route discovery for a poor link, thereby reducing the overhead involved and improving the throughput of the network while maintaining network connectivity. Power control is also implemented not only to save energy but also to improve the network performance. Using simulations, we show the performance improvement attained in the network in terms of packet delivery ratio, routing overhead, and residual energy of the network.

Energy Efficient Link Aware Routing with Power Control in Wireless Ad Hoc Networks

Directory of Open Access Journals (Sweden)

Jeevaa Katiravan

2015-01-01

Full Text Available In wireless ad hoc networks, the traditional routing protocols make the route selection based on minimum distance between the nodes and the minimum number of hop counts. Most of the routing decisions do not consider the condition of the network such as link quality and residual energy of the nodes. Also, when a link failure occurs, a route discovery mechanism is initiated which incurs high routing overhead. If the broadcast nature and the spatial diversity of the wireless communication are utilized efficiently it becomes possible to achieve improvement in the performance of the wireless networks. In contrast to the traditional routing scheme which makes use of a predetermined route for packet transmission, such an opportunistic routing scheme defines a predefined forwarding candidate list formed by using single network metrics. In this paper, a protocol is proposed which uses multiple metrics such as residual energy and link quality for route selection and also includes a monitoring mechanism which initiates a route discovery for a poor link, thereby reducing the overhead involved and improving the throughput of the network while maintaining network connectivity. Power control is also implemented not only to save energy but also to improve the network performance. Using simulations, we show the performance improvement attained in the network in terms of packet delivery ratio, routing overhead, and residual energy of the network.

Performance of an Orthogonal Multicarrier CDMA System in a Multicell/Multipath Environment

Energy Technology Data Exchange (ETDEWEB)

Yoon, W.S. [Ajou University, Suwon (Korea)

1999-08-01

We have considered an improved orthogonal multicarrier (MC) CDMA system. This system combines the advantages of both DS-CDMA with a concatenated spreading scheme and an MC modulation technique to combat the effects of a multipath fading channel and intersymbol interference (IS). The performance of the system is analyzed under a multicell, multiuser, and multipath Rician fading channel. The system is shown to outperform the orthogonal MC-CDMA system with a conventional PN sequence. (author). 4 refs., 3 figs.

Multichannel Baseband Processor for Wideband CDMA

Directory of Open Access Journals (Sweden)

Jim Lin

2005-07-01

Full Text Available The system architecture of the cellular base station modem engine (CBME is described. The CBME is a single-chip multichannel transceiver capable of processing and demodulating signals from multiple users simultaneously. It is optimized to process different classes of code-division multiple-access (CDMA signals. The paper will show that through key functional system partitioning, tightly coupled small digital signal processing cores, and time-sliced reuse architecture, CBME is able to achieve a high degree of algorithmic flexibility while maintaining efficiency. The paper will also highlight the implementation and verification aspects of the CBME chip design. In this paper, wideband CDMA is used as an example to demonstrate the architecture concept.

Wireless Energy and Information Transmission in FSO and RF-FSO Links

KAUST Repository

Makki, Behrooz

2017-09-22

We propose and analyze a wireless energy and information transmission scheme in free-space optical (FSO) links. The results are presented for both quasi-static and fast-fading conditions. We derive closed-form expressions for throughput, outage probability and optimal power allocation optimizing the system throughput/outage probability. Finally, we complement the FSO link with an additional radio frequency (RF) link to create a hybrid RF-FSO system and reduce the system outage probability. The results show that joint implementation of the RF and FSO links leads to considerable performance improvement, compared to the cases with only FSO-based communication.

A Combined Antenna Arrays and Reverse-Link Synchronous DS-CDMA System over Frequency-Selective Fading Channels with Power Control Error

Directory of Open Access Journals (Sweden)

Yong-Seok Kim

2004-08-01

Full Text Available An improved antenna array (AA has been introduced, in which reverse-link synchronous transmission technique (RLSTT is incorporated to effectively make better an estimation of covariance matrices at a beamformer-RAKE receiver. While RLSTT is effective in the first finger at the RAKE receiver in order to reject multiple-access interference (MAI, the beamformer estimates the desired user's complex weights, enhancing its signal and reducing cochannel interference (CCI from the other directions. In this work, it is attempted to provide a comprehensive analysis of user capacity which reflects several important factors such as the shape of multipath intensity profile (MIP, the number of antennas, and power control error (PCE. Theoretical analysis, confirmed by the simulations, demonstrates that the orthogonality provided by employing RLSTT along with AA may make the DS-CDMA system insensitive to the PCE even with fewer numbers of antennas.

A novel PON based UMTS broadband wireless access network architecture with an algorithm to guarantee end to end QoS

Science.gov (United States)

Sana, Ajaz; Hussain, Shahab; Ali, Mohammed A.; Ahmed, Samir

2007-09-01

In this paper we proposes a novel Passive Optical Network (PON) based broadband wireless access network architecture to provide multimedia services (video telephony, video streaming, mobile TV, mobile emails etc) to mobile users. In the conventional wireless access networks, the base stations (Node B) and Radio Network Controllers (RNC) are connected by point to point T1/E1 lines (Iub interface). The T1/E1 lines are expensive and add up to operating costs. Also the resources (transceivers and T1/E1) are designed for peak hours traffic, so most of the time the dedicated resources are idle and wasted. Further more the T1/E1 lines are not capable of supporting bandwidth (BW) required by next generation wireless multimedia services proposed by High Speed Packet Access (HSPA, Rel.5) for Universal Mobile Telecommunications System (UMTS) and Evolution Data only (EV-DO) for Code Division Multiple Access 2000 (CDMA2000). The proposed PON based back haul can provide Giga bit data rates and Iub interface can be dynamically shared by Node Bs. The BW is dynamically allocated and the unused BW from lightly loaded Node Bs is assigned to heavily loaded Node Bs. We also propose a novel algorithm to provide end to end Quality of Service (QoS) (between RNC and user equipment).The algorithm provides QoS bounds in the wired domain as well as in wireless domain with compensation for wireless link errors. Because of the air interface there can be certain times when the user equipment (UE) is unable to communicate with Node B (usually referred to as link error). Since the link errors are bursty and location dependent. For a proposed approach, the scheduler at the Node B maps priorities and weights for QoS into wireless MAC. The compensations for errored links is provided by the swapping of services between the active users and the user data is divided into flows, with flows allowed to lag or lead. The algorithm guarantees (1)delay and throughput for error-free flows,(2)short term fairness

Nonlinear Multiuser Receiver for Optimized Chaos-Based DS-CDMA Systems

Directory of Open Access Journals (Sweden)

S. Shaerbaf

2011-09-01

Full Text Available Chaos based communications have drawn increasing attention over the past years. Chaotic signals are derived from non-linear dynamic systems. They are aperiodic, broadband and deterministic signals that appear random in the time domain. Because of these properties, chaotic signals have been proposed to generate spreading sequences for wide-band secure communication recently. Like conventional DS-CDMA systems, chaos-based CDMA systems suffer from multi-user interference (MUI due to other users transmitting in the cell. In this paper, we propose a novel method based on radial basis function (RBF for both blind and non-blind multiuser detection in chaos-based DS-CDMA systems. We also propose a new method for optimizing generation of binary chaotic sequences using Genetic Algorithm. Simulation results show that our proposed nonlinear receiver with optimized chaotic sequences outperforms in comparison to other conventional detectors such as a single-user detector, decorrelating detector and minimum mean square error detector, particularly for under-loaded CDMA condition, which the number of active users is less than processing gain.

An Accurate Link Correlation Estimator for Improving Wireless Protocol Performance

Science.gov (United States)

Zhao, Zhiwei; Xu, Xianghua; Dong, Wei; Bu, Jiajun

2015-01-01

Wireless link correlation has shown significant impact on the performance of various sensor network protocols. Many works have been devoted to exploiting link correlation for protocol improvements. However, the effectiveness of these designs heavily relies on the accuracy of link correlation measurement. In this paper, we investigate state-of-the-art link correlation measurement and analyze the limitations of existing works. We then propose a novel lightweight and accurate link correlation estimation (LACE) approach based on the reasoning of link correlation formation. LACE combines both long-term and short-term link behaviors for link correlation estimation. We implement LACE as a stand-alone interface in TinyOS and incorporate it into both routing and flooding protocols. Simulation and testbed results show that LACE: (1) achieves more accurate and lightweight link correlation measurements than the state-of-the-art work; and (2) greatly improves the performance of protocols exploiting link correlation. PMID:25686314

Integration and analysis of neighbor discovery and link quality estimation in wireless sensor networks.

Science.gov (United States)

Radi, Marjan; Dezfouli, Behnam; Abu Bakar, Kamalrulnizam; Abd Razak, Shukor

2014-01-01

Network connectivity and link quality information are the fundamental requirements of wireless sensor network protocols to perform their desired functionality. Most of the existing discovery protocols have only focused on the neighbor discovery problem, while a few number of them provide an integrated neighbor search and link estimation. As these protocols require a careful parameter adjustment before network deployment, they cannot provide scalable and accurate network initialization in large-scale dense wireless sensor networks with random topology. Furthermore, performance of these protocols has not entirely been evaluated yet. In this paper, we perform a comprehensive simulation study on the efficiency of employing adaptive protocols compared to the existing nonadaptive protocols for initializing sensor networks with random topology. In this regard, we propose adaptive network initialization protocols which integrate the initial neighbor discovery with link quality estimation process to initialize large-scale dense wireless sensor networks without requiring any parameter adjustment before network deployment. To the best of our knowledge, this work is the first attempt to provide a detailed simulation study on the performance of integrated neighbor discovery and link quality estimation protocols for initializing sensor networks. This study can help system designers to determine the most appropriate approach for different applications.

Integration and Analysis of Neighbor Discovery and Link Quality Estimation in Wireless Sensor Networks

Directory of Open Access Journals (Sweden)

Marjan Radi

2014-01-01

Full Text Available Network connectivity and link quality information are the fundamental requirements of wireless sensor network protocols to perform their desired functionality. Most of the existing discovery protocols have only focused on the neighbor discovery problem, while a few number of them provide an integrated neighbor search and link estimation. As these protocols require a careful parameter adjustment before network deployment, they cannot provide scalable and accurate network initialization in large-scale dense wireless sensor networks with random topology. Furthermore, performance of these protocols has not entirely been evaluated yet. In this paper, we perform a comprehensive simulation study on the efficiency of employing adaptive protocols compared to the existing nonadaptive protocols for initializing sensor networks with random topology. In this regard, we propose adaptive network initialization protocols which integrate the initial neighbor discovery with link quality estimation process to initialize large-scale dense wireless sensor networks without requiring any parameter adjustment before network deployment. To the best of our knowledge, this work is the first attempt to provide a detailed simulation study on the performance of integrated neighbor discovery and link quality estimation protocols for initializing sensor networks. This study can help system designers to determine the most appropriate approach for different applications.

Average Likelihood Methods of Classification of Code Division Multiple Access (CDMA)

Science.gov (United States)

2016-05-01

subject to code matrices that follows the structure given by (113). [⃗ yR y⃗I ] = √ Es 2L [ GR1 −GI1 GI2 GR2 ] [ QR −QI QI QR ] [⃗ bR b⃗I ] + [⃗ nR n⃗I... QR ] [⃗ b+ b⃗− ] + [⃗ n+ n⃗− ] (115) The average likelihood for type 4 CDMA (116) is a special case of type 1 CDMA with twice the code length and...AVERAGE LIKELIHOOD METHODS OF CLASSIFICATION OF CODE DIVISION MULTIPLE ACCESS (CDMA) MAY 2016 FINAL TECHNICAL REPORT APPROVED FOR PUBLIC RELEASE

A Novel Method of SIR Measurement for Power Control in CDMA Systems

International Nuclear Information System (INIS)

Yu, J; Wu, S B; He, J Z

2006-01-01

CDMA is interference limited multiple access system. Power control is an effective way to reduce co-channel interference and solve the near-far problem. Consequently, it can improve the system capacity, and make higher data rate possible. CDMA2000 employs fast closed-loop power control in reverse link to combat channel fading, and the estimation of signal to interference ratio (SIR) is required for closed-loop power control. Transmitting power is adjusted by comparing the SIR estimation with SIR target. So, it is crucial to measure the SIR of received signal accurately. Traditional measurement methods mostly depend on pilot signal strongly, when the pilots are few, there is a greater error brought to the measurement of SIR. In this paper, we discuss the SIR measurement of the received signal under the fewer pilots condition (especially only one pilot symbol) and present a novel SIR measurement method. According to the simulation, the numerical results indicate that the SIR measured by the proposed method is more accurate than the SIR measured by conventional method under fewer pilots condition

CDMA2000 Y WCDMA

Directory of Open Access Journals (Sweden)

Jaime Sánchez García

2005-01-01

Full Text Available Este artículo ofrece un panorama general de los sistemas de comunicaciones móviles celulares de tercera generación (3G que han tenido una mayor aceptación (CDMA2000 y WCDMA en el mercado, y una comparación basada en los puntos principales donde los sistemas difieren que indica las ventajas y desventajas de cada uno. Los sistemas de comunicaciones móviles celulares 3G ofrecen mayores capacidades de transmisión a los de segunda generación (2G, y permiten brindar, además de los tradicionales servicios de telefonía celular, servicios de comunicación de datos a velocidades más altas que los de 2G. Las redes CDMA2000 y WCDMA forman parte del estándar IMT-2000 definido por la Unión Internacional de Telecomunicaciones (ITU para sistemas de comunicaciones inalámbricas de tercera generación; éstas son redes de banda ancha que ofrecen mayores velocidades de transmisión de datos, servicios de internet y aplicaciones multimedia

0.4 THz Photonic-Wireless Link With 106 Gb/s Single Channel Bitrate

DEFF Research Database (Denmark)

Jia, Shi; Pang, Xiaodan; Ozolins, Oskars

2018-01-01

To accommodate the demand of exponentially increased global wireless data traffic, the prospective data rates for wireless communication in the market place will soon reach 100 Gb/s and beyond. In the lab environment, wireless transmission throughput has been elevated to the level of over 100 Gb....../s attributed to the development of photonic-assisted millimeter wave and terahertz (THz) technologies. However, most of recent demonstrations with over 100 Gb/s data rates are based on spatial or frequency division multiplexing techniques, resulting in increased system's complexity and energy consumption. Here......, we experimentally demonstrate a single channel 0.4 THz photonic-wireless link achieving a net data rate of beyond 100 Gb/s by using a single pair of THz emitter and receiver, without employing any spatial/frequency division multiplexing techniques. The high throughput up to 106 Gb/s within a single...

The research of atmospheric 2D optical PPM CDMA system with turbo coding

Science.gov (United States)

Zhou, Xiuli; Li, Zaoxia

2007-11-01

The atmospheric two-dimensional optical code-division multiple-access (CDMA) systems using pulse-position modulation (PPM) and Turbo-coded were presented. We analyzed the bit-error rate (BER) of the proposed system using pulse-position modulation (PPM) with considering the effects of the scintillation, avalanche photodiode noise, thermal noise, and multi-user interference. We showed that the atmospheric two dimensional (2D) optical PPM CDMA systems can realize high-speed communications when the logarithm variance of the scintillation is less than 0.1, and the turbo-coded atmospheric optical CDMA system has better bit error rate(BER) performance than the atmospheric optical PPM CDMA systems without turbo-coded. We also showed that the turbo-coded system has better performance than the multi-user detection system.

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...

Fast frequency hopping codes applied to SAC optical CDMA network

Science.gov (United States)

Tseng, Shin-Pin

2015-06-01

This study designed a fast frequency hopping (FFH) code family suitable for application in spectral-amplitude-coding (SAC) optical code-division multiple-access (CDMA) networks. The FFH code family can effectively suppress the effects of multiuser interference and had its origin in the frequency hopping code family. Additional codes were developed as secure codewords for enhancing the security of the network. In considering the system cost and flexibility, simple optical encoders/decoders using fiber Bragg gratings (FBGs) and a set of optical securers using two arrayed-waveguide grating (AWG) demultiplexers (DeMUXs) were also constructed. Based on a Gaussian approximation, expressions for evaluating the bit error rate (BER) and spectral efficiency (SE) of SAC optical CDMA networks are presented. The results indicated that the proposed SAC optical CDMA network exhibited favorable performance.

Broadband nanophotonic wireless links and networks using on-chip integrated plasmonic antennas.

Science.gov (United States)

Yang, Yuanqing; Li, Qiang; Qiu, Min

2016-01-19

Owing to their high capacity and flexibility, broadband wireless communications have been widely employed in radio and microwave regimes, playing indispensable roles in our daily life. Their optical analogs, however, have not been demonstrated at the nanoscale. In this paper, by exploiting plasmonic nanoantennas, we demonstrate the complete design of broadband wireless links and networks in the realm of nanophotonics. With a 100-fold enhancement in power transfer superior to previous designs as well as an ultrawide bandwidth that covers the entire telecommunication wavelength range, such broadband nanolinks and networks are expected to pave the way for future optical integrated nanocircuits.

Iterative Decoding for an Optical CDMA based Laser communication System

International Nuclear Information System (INIS)

Kim, Jin Young; Kim, Eun Cheol; Cha, Jae Sang

2008-01-01

An optical CDMA(code division multiple access)based Laser communication system has attracted much attention since it requires minimal optical Laser signal processing and it is virtually delay free, while from the theoretical point of view, its performance depends on the auto and cross correlation properties of employed sequences. Various kinds of channel coding schemes for optical CDMA based Laser communication systems have been proposed and analyzed to compensate nonideal channel and receiver conditions in impaired photon channels. In this paper, we propose and analyze an iterative decoding of optical CDMA based Laser communication signals for both shot noise limited and thermal noise limited systems. It is assumed that optical channel is an intensity modulated (IM)channel and direct detection scheme is employed to detect the received optical signal. The performance is evaluated in terms of bit error probability and throughput. It is demonstrated that the BER and throughput performance is substantially improved with interleaver length for a fixed code rate and with alphabet size of PPM (pulse position modulation). Also, the BER and throughput performance is significantly enhanced with the number of iterations for decoding process. The results in this paper can be applied to the optical CDMA based Laser communication network with multiple access applications

Iterative Decoding for an Optical CDMA based Laser communication System

Energy Technology Data Exchange (ETDEWEB)

Kim, Jin Young; Kim, Eun Cheol [Kwangwoon Univ., Seoul (Korea, Republic of); Cha, Jae Sang [Seoul National Univ. of Technology, Seoul (Korea, Republic of)

2008-11-15

An optical CDMA(code division multiple access)based Laser communication system has attracted much attention since it requires minimal optical Laser signal processing and it is virtually delay free, while from the theoretical point of view, its performance depends on the auto and cross correlation properties of employed sequences. Various kinds of channel coding schemes for optical CDMA based Laser communication systems have been proposed and analyzed to compensate nonideal channel and receiver conditions in impaired photon channels. In this paper, we propose and analyze an iterative decoding of optical CDMA based Laser communication signals for both shot noise limited and thermal noise limited systems. It is assumed that optical channel is an intensity modulated (IM)channel and direct detection scheme is employed to detect the received optical signal. The performance is evaluated in terms of bit error probability and throughput. It is demonstrated that the BER and throughput performance is substantially improved with interleaver length for a fixed code rate and with alphabet size of PPM (pulse position modulation). Also, the BER and throughput performance is significantly enhanced with the number of iterations for decoding process. The results in this paper can be applied to the optical CDMA based Laser communication network with multiple access applications.

Energy Link Optimization in a Wireless Power Transfer Grid under Energy Autonomy Based on the Improved Genetic Algorithm

Directory of Open Access Journals (Sweden)

Zhihao Zhao

2016-08-01

Full Text Available In this paper, an optimization method is proposed for the energy link in a wireless power transfer grid, which is a regional smart microgrid comprised of distributed devices equipped with wireless power transfer technology in a certain area. The relevant optimization model of the energy link is established by considering the wireless power transfer characteristics and the grid characteristics brought in by the device repeaters. Then, a concentration adaptive genetic algorithm (CAGA is proposed to optimize the energy link. The algorithm avoided the unification trend by introducing the concentration mechanism and a new crossover method named forward order crossover, as well as the adaptive parameter mechanism, which are utilized together to keep the diversity of the optimization solution groups. The results show that CAGA is feasible and competitive for the energy link optimization in different situations. This proposed algorithm performs better than its counterparts in the global convergence ability and the algorithm robustness.

Crest Factor Reduction in MC-CDMA Employing Carrier Interferometry Codes

Directory of Open Access Journals (Sweden)

Natarajan Balasubramaniam

2004-01-01

Full Text Available This paper addresses signal compactness issues in MC-CDMA employing carrier interferometry codes using the measure of crest factor (CF. Carrier interferometry codes, applied to N -carrier MC-CDMA systems, enable 2N users to simultaneously share the system bandwidth with minimal degradation in performance (relative to the N -orthogonal-user case. First, for a fully loaded ( K=N and K=2N users MC-CDMA system with practical values of N , it is shown that the CF in downlink transmission demonstrates desirable properties of low mean and low variance. The downlink CF degrades when the number of users in the system decreases. Next, the high CF observed in the uplink is characterized and the poor CF in a partially loaded downlink as well as uplink is effectively combated using Schroeder's analytical CF reduction techniques.

mm-Wave Hybrid Photonic Wireless Links for Ultra-High Speed Wireless Transmissions

DEFF Research Database (Denmark)

Rommel, Simon; Vegas Olmos, Juan José; Tafur Monroy, Idelfonso

Hybrid photonic-wireless transmission schemes in the mm-wave frequency range are promising candidates to enable the multi-gigabit per second data communications required from wireless and mobile networks of the 5th and future generations. Large FCC spectrum allocations for wireless transmission...

Single Carrier Cyclic Prefix-Assisted CDMA System with Frequency Domain Equalization for High Data Rate Transmission

Directory of Open Access Journals (Sweden)

Madhukumar A. S.

2004-01-01

Full Text Available Multiple-access interference and interfinger interference limit the capacity of conventional single-carrier DS-CDMA systems. Even though multicarrier CDMA posses the advantages of conventional CDMA and OFDM, it suffers from two major implementation difficulties such as peak-to-average power ratio and high sensitivity to frequency offset and RF phase noise. A novel approach based on single-carrier cyclic prefix-assisted CDMA has been proposed to overcome the disadvantages of single-carrier CDMA and multicarrier modulation. The usefulness of the proposed approach for high-speed packet access with simplified channel estimation procedures are investigated in this paper. The paper also proposes a data-dependent pilot structure for the downlink transmission of the proposed system for enhancing pilot-assisted channel estimation in frequency domain. The performance of the proposed pilot structure is compared against the data-independent common pilot structure. The proposed system is extensively simulated for different channel parameters with different channel estimation and equalization methods and the results are compared against conventional multicarrier CDMA systems with identical system specifications.

Energy-Efficient Link-Layer Jamming Attacks against Wireless Sensor Network MAC Protocols

NARCIS (Netherlands)

Law, Y.W.; van Hoesel, L.F.W.; Doumen, J.M.; Hartel, Pieter H.; Havinga, Paul J.M.; Atluri, V.; Samarati, P.; Ning, P.; Du, W.

2005-01-01

A typical wireless sensor node has little protection against radio jamming. The situation becomes worse if energy efficient jamming can be achieved by exploiting knowledge of the data link layer. Encrypting the packets may help prevent the jammer from taking actions based on the content of the

Iterative Overlap FDE for Multicode DS-CDMA

Science.gov (United States)

Takeda, Kazuaki; Tomeba, Hiromichi; Adachi, Fumiyuki

Recently, a new frequency-domain equalization (FDE) technique, called overlap FDE, that requires no GI insertion was proposed. However, the residual inter/intra-block interference (IBI) cannot completely be removed. In addition to this, for multicode direct sequence code division multiple access (DS-CDMA), the presence of residual interchip interference (ICI) after FDE distorts orthogonality among the spreading codes. In this paper, we propose an iterative overlap FDE for multicode DS-CDMA to suppress both the residual IBI and the residual ICI. In the iterative overlap FDE, joint minimum mean square error (MMSE)-FDE and ICI cancellation is repeated a sufficient number of times. The bit error rate (BER) performance with the iterative overlap FDE is evaluated by computer simulation.

A Comparative Field Monitoring of Column Shortenings in Tall Buildings Using Wireless and Wired Sensor Network Systems

Directory of Open Access Journals (Sweden)

Sungho Lee

2016-01-01

Full Text Available A comparative field measurement for column shortening of tall buildings is presented in this study, with a focus on the reliability and stability of a wireless sensor network. A wireless sensor network was used for monitoring the column shortenings of a 58-story building under construction. The wireless sensor network, which was composed of sensor and master nodes, employed the ultra-high-frequency band and CDMA communication methods. To evaluate the reliability and stability of the wireless sensor network system, the column shortenings were also measured using a conventional wired monitoring system. Two vibration wire gauges were installed in each of the selected 7 columns and 3 walls. Measurements for selected columns and walls were collected for 270 days after casting of the concrete. The results measured by the wireless sensor network were compared with the results of the conventional method. The strains and column shortenings measured using both methods showed good agreement for all members. It was verified that the column shortenings of tall buildings could be monitored using the wireless sensor network system with its reliability and stability.

Monte-Carlo Simulation for PDC-Based Optical CDMA System

Directory of Open Access Journals (Sweden)

FAHIM AZIZ UMRANI

2010-10-01

Full Text Available This paper presents the Monte-Carlo simulation of Optical CDMA (Code Division Multiple Access systems, and analyse its performance in terms of the BER (Bit Error Rate. The spreading sequence chosen for CDMA is Perfect Difference Codes. Furthermore, this paper derives the expressions of noise variances from first principles to calibrate the noise for both bipolar (electrical domain and unipolar (optical domain signalling required for Monte-Carlo simulation. The simulated results conform to the theory and show that the receiver gain mismatch and splitter loss at the transceiver degrades the system performance.

Why is CDMA the solution for mobile satellite communication

Science.gov (United States)

Gilhousen, Klein S.; Jacobs, Irwin M.; Padovani, Roberto; Weaver, Lindsay A.

1989-01-01

It is demonstrated that spread spectrum Code Division Multiple Access (CDMA) systems provide an economically superior solution to satellite mobile communications by increasing the system maximum capacity with respect to single channel per carrier Frequency Division Multiple Access (FDMA) systems. Following the comparative analysis of CDMA and FDMA systems, the design of a model that was developed to test the feasibility of the approach and the performance of a spread spectrum system in a mobile environment. Results of extensive computer simulations as well as laboratory and field tests results are presented.

Contribution to Synchronization and Tracking Modelisation in a CDMA Receiver

Directory of Open Access Journals (Sweden)

Aicha Alami Hassani

2013-01-01

Full Text Available We propose and analyze a noncoherent receiver with PN code tracking for direct sequence code division multiple access (DS-CDMA communication systems. We employ the delay-lock loop (DLL architectures for the tracking stage. The choice of DLL parameters is studied with special focus on DS-CDMA communication systems and orthogonality conditions. We described the modeling and simulation of the NCO using hardware description language VHDL. Details of the VHDL implementation are shown.

Modeling and Performance Analysis of 10 Gbps Inter-satellite Optical Wireless Communication Link

Science.gov (United States)

Singh, Mehtab

2017-12-01

Free-space optical (FSO) communication has the advantages of two of the most predominant data transmission technologies - optical fiber communication and wireless communication. Most of the technical aspects of FSO are similar to that of optical fiber communication, with major difference in the information signal propagation medium which is free space in case of FSO rather than silica glass in optical fiber communication. One of the most important applications of FSO is inter-satellite optical wireless communication (IsOWC) links which will be deployed in the future in space. The IsOWC links have many advantages over the previously existing microwave satellite communication technologies such as higher bandwidth, lower power consumption, low cost of implementation, light size, and weight. In this paper, modeling and performance analysis of a 10-Gbps inter-satellite communication link with two satellites separated at a distance of 1,200 km has been done using OPTISYSTEM simulation software. Performance has been analyzed on the basis of quality factor, signal to noise ratio (SNR), and total power of the received signal.

Real-time 2.5  Gbit/s spatial circuit switching on W-band wireless links

DEFF Research Database (Denmark)

Rodríguez, Sebastián; Morales Vicente, Alvaro; Gallardo, Omar

2017-01-01

A spatial circuit switching system based on a beam steering application for W-band wireless links is proposed and experimentally demonstrated. The system enables two simultaneous transmissions of a 2.5 Gbit∕s data signal over a carrier of 81 GHz, while allowing the receiver to dynamically switch...... between them. The performance of the system is tested with the real-time measurements of the BER, achieving values below the FEC limit for 7% of overhead and serving to prove the viability of wireless spatial circuit switching in the next generation of wireless access networks....

Interference Cancellation Technique Based on Discovery of Spreading Codes of Interference Signals and Maximum Correlation Detection for DS-CDMA System

Science.gov (United States)

Hettiarachchi, Ranga; Yokoyama, Mitsuo; Uehara, Hideyuki

This paper presents a novel interference cancellation (IC) scheme for both synchronous and asynchronous direct-sequence code-division multiple-access (DS-CDMA) wireless channels. In the DS-CDMA system, the multiple access interference (MAI) and the near-far problem (NFP) are the two factors which reduce the capacity of the system. In this paper, we propose a new algorithm that is able to detect all interference signals as an individual MAI signal by maximum correlation detection. It is based on the discovery of all the unknowing spreading codes of the interference signals. Then, all possible MAI patterns so called replicas are generated as a summation of interference signals. And the true MAI pattern is found by taking correlation between the received signal and the replicas. Moreover, the receiver executes MAI cancellation in a successive manner, removing all interference signals by single-stage. Numerical results will show that the proposed IC strategy, which alleviates the detrimental effect of the MAI and the near-far problem, can significantly improve the system performance. Especially, we can obtain almost the same receiving characteristics as in the absense of interference for asynchrnous system when received powers are equal. Also, the same performances can be seen under any received power state for synchronous system.

Variable-length code construction for incoherent optical CDMA systems

Science.gov (United States)

Lin, Jen-Yung; Jhou, Jhih-Syue; Wen, Jyh-Horng

2007-04-01

The purpose of this study is to investigate the multirate transmission in fiber-optic code-division multiple-access (CDMA) networks. In this article, we propose a variable-length code construction for any existing optical orthogonal code to implement a multirate optical CDMA system (called as the multirate code system). For comparison, a multirate system where the lower-rate user sends each symbol twice is implemented and is called as the repeat code system. The repetition as an error-detection code in an ARQ scheme in the repeat code system is also investigated. Moreover, a parallel approach for the optical CDMA systems, which is proposed by Marić et al., is also compared with other systems proposed in this study. Theoretical analysis shows that the bit error probability of the proposed multirate code system is smaller than other systems, especially when the number of lower-rate users is large. Moreover, if there is at least one lower-rate user in the system, the multirate code system accommodates more users than other systems when the error probability of system is set below 10 -9.

A unifying paradigm for IS-95 CDMA system

Energy Technology Data Exchange (ETDEWEB)

Lee, K.R.; Kim, H.J.; Kim, W.K. [Korea University, Seoul (Korea, Republic of)

1997-05-01

An important method of generating binary sequences is by means of a shift register (SR) configuration such as Linear Feedback Shift Register (LFSR). The SR configuration is used for CRC, interleaver, convolutional encoder and PN generators in IS-95 CDMA system. In this regard, CRC, interleaver, convolutional encoder can be seen as input-driven configurations, and PN generator can be seen as an autonomous configuration. In this paper we propose some alternative schemes of PN code generator which has the different structure from conventional one. The implementations can be used toward building a single chip that handles most of the signal processing that occur at the front-end of IS-95 CDMA transmission. (author). 5 refs., 5 figs.

High capacity hybrid optical fiber-wireless links in 75–300GHz band

DEFF Research Database (Denmark)

Cavalcante, Lucas Costa Pereira; Vegas Olmos, Juan José; Tafur Monroy, Idelfonso

2014-01-01

Seamless convergence of fiber-optic and the wireless networks is of great interest for enabling transparent delivery of broadband services to users in different locations, including both metropolitan and rural areas. Current demand of bandwidth by end-users, especially using mobile devices......, is seeding the need to use bands located at the millimeter-wave region (30–300 GHz), mainly because of its inherent broadband nature. In our lab, we have conducted extensive research on high-speed photonic-wireless links in the W-band (75–110GHz). In this paper, we will present our latest findings...

DPLL implementation in carrier acquisition and tracking for burst DS-CDMA receivers.

Science.gov (United States)

Guan, Yun-feng; Zhang, Zhao-yang; Lai, Li-feng

2003-01-01

This paper presents the architectures, algorithms, and implementation considerations of the digital phase locked loop (DPLL) used for burst-mode packet DS-CDMA receivers. As we know, carrier offset is a rather challenging problem in CDMA system. According to different applications, different DPLL forms should be adopted to correct different maximum carrier offset in CDMA systems. One classical DPLL and two novel DPLL forms are discussed in the paper. The acquisition range of carrier offset can be widened by using the two novel DPLL forms without any performance degradation such as longer acquisition time or larger variance of the phase error. The maximum acquisition range is 1/(4T), where T is the symbol period. The design can be implemented by FPGA directly.

Optical-wireless-optical full link for polarization multiplexing quadrature amplitude/phase modulation signal transmission.

Science.gov (United States)

Li, Xinying; Yu, Jianjun; Chi, Nan; Zhang, Junwen

2013-11-15

We propose and experimentally demonstrate an optical wireless integration system at the Q-band, in which up to 40 Gb/s polarization multiplexing multilevel quadrature amplitude/phase modulation (PM-QAM) signal can be first transmitted over 20 km single-mode fiber-28 (SMF-28), then delivered over a 2 m 2 × 2 multiple-input multiple-output wireless link, and finally transmitted over another 20 km SMF-28. The PM-QAM modulated wireless millimeter-wave (mm-wave) signal at 40 GHz is generated based on the remote heterodyning technique, and demodulated by the radio-frequency transparent photonic technique based on homodyne coherent detection and baseband digital signal processing. The classic constant modulus algorithm equalization is used at the receiver to realize polarization demultiplexing of the PM-QAM signal. For the first time, to the best of our knowledge, we realize the conversion of the PM-QAM modulated wireless mm-wave signal to the optical signal as well as 20 km fiber transmission of the converted optical signal.

Topology control algorithm for wireless sensor networks based on Link forwarding

Science.gov (United States)

Pucuo, Cairen; Qi, Ai-qin

2018-03-01

The research of topology control could effectively save energy and increase the service life of network based on wireless sensor. In this paper, a arithmetic called LTHC (link transmit hybrid clustering) based on link transmit is proposed. It decreases expenditure of energy by changing the way of cluster-node’s communication. The idea is to establish a link between cluster and SINK node when the cluster is formed, and link-node must be non-cluster. Through the link, cluster sends information to SINK nodes. For the sake of achieving the uniform distribution of energy on the network, prolongate the network survival time, and improve the purpose of communication, the communication will cut down much more expenditure of energy for cluster which away from SINK node. In the two aspects of improving the traffic and network survival time, we find that the LTCH is far superior to the traditional LEACH by experiments.

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.

Secure Communications in High Speed Fiber Optical Networks Using Code Division Multiple Access (CDMA) Transmission

Energy Technology Data Exchange (ETDEWEB)

Han, I; Bond, S; Welty, R; Du, Y; Yoo, S; Reinhardt, C; Behymer, E; Sperry, V; Kobayashi, N

2004-02-12

This project is focused on the development of advanced components and system technologies for secure data transmission on high-speed fiber optic data systems. This work capitalizes on (1) a strong relationship with outstanding faculty at the University of California-Davis who are experts in high speed fiber-optic networks, (2) the realization that code division multiple access (CDMA) is emerging as a bandwidth enhancing technique for fiber optic networks, (3) the realization that CDMA of sufficient complexity forms the basis for almost unbreakable one-time key transmissions, (4) our concepts for superior components for implementing CDMA, (5) our expertise in semiconductor device processing and (6) our Center for Nano and Microtechnology, which is where the majority of the experimental work was done. Here we present a novel device concept, which will push the limits of current technology, and will simultaneously solve system implementation issues by investigating new state-of-the-art fiber technologies. This will enable the development of secure communication systems for the transmission and reception of messages on deployed commercial fiber optic networks, through the CDMA phase encoding of broad bandwidth pulses. CDMA technology has been developed as a multiplexing technology, much like wavelength division multiplexing (WDM) or time division multiplexing (TDM), to increase the potential number of users on a given communication link. A novel application of the techniques created for CDMA is to generate secure communication through physical layer encoding. Physical layer encoding devices are developed which utilize semiconductor waveguides with fast carrier response times to phase encode spectral components of a secure signal. Current commercial technology, most commonly a spatial light modulator, allows phase codes to be changed at rates of only 10's of Hertz ({approx}25ms response). The use of fast (picosecond to nanosecond) carrier dynamics of semiconductors

30 pJ/b, 67 Mbps, Centimeter-to-Meter Range Data Telemetry With an IR-UWB Wireless Link.

Science.gov (United States)

Ebrazeh, Ali; Mohseni, Pedram

2015-06-01

This paper reports an energy-efficient, impulse radio ultra wideband (IR-UWB) wireless link operating in 3-5 GHz for data telemetry over centimeter-to-meter range distances at rates extended to tens of Mbps. The link comprises an all-digital, integrated transmitter (TX) fabricated in 90 nm 1P/9M CMOS that incorporates a waveform-synthesis pulse generator and a timing generator for on-off-keying (OOK) pulse modulation and phase scrambling. The link also incorporates an energy-detection receiver (RX) realized with commercial off-the-shelf (COTS) components that performs radio-frequency (RF) filtering, amplification, logarithmic power detection for data demodulation and automatic level control for robust operation in the presence of distance variations. Employing a miniaturized, UWB, chip antenna for the TX and RX, wireless transmission of pseudo-random binary sequence (PRBS) data at rates up to 50 Mbps over 10 cm-1 m is shown. Further, employing a high-gain horn antenna for the RX, wireless transmission of PRBS data at rates up to 67 Mbps over 50 cm-4 m is shown with a TX energy consumption of 30 pJ/b (i.e., power consumption of 2 mW) from 1.2 V. The measured bit error rate (BER) in both cases is wireless recording of the background current of a carbon-fiber microelectrode (CFM) in one fast-scan cyclic voltammetry (FSCV) scan using the IR-UWB link are also included, exhibiting excellent match with those obtained from a conventional frequency-shift-keyed (FSK) link at ~433 MHz.

Securing the communication of medical information using local biometric authentication and commercial wireless links.

Science.gov (United States)

Ivanov, Vladimir I; Yu, Paul L; Baras, John S

2010-09-01

Medical information is extremely sensitive in nature - a compromise, such as eavesdropping or tampering by a malicious third party, may result in identity theft, incorrect diagnosis and treatment, and even death. Therefore, it is important to secure the transfer of medical information from the patient to the recording system. We consider a portable, wireless device transferring medical information to a remote server. We decompose this problem into two sub-problems and propose security solutions to each of them: (1) to secure the link between the patient and the portable device, and (2) to secure the link between the portable device and the network. Thus we push the limits of the network security to the edge by authenticating the user using their biometric information; authenticating the device to the network at the physical layer; and strengthening the security of the wireless link with a key exchange mechanism. The proposed authentication methods can be used for recording the readings of medical data in a central database and for accessing medical records in various settings.

MC-DS-CDMA System based on DWT and STBC in ITU Multipath Fading Channels Model

Directory of Open Access Journals (Sweden)

Nader Abdullah Khadam

2018-03-01

Full Text Available In this paper, the performance of multicarrier direct sequence code division multiple access (MC-DS-CDMA in fixed MC-DS-CDMA and Mobile MC-DS-CDMA applications have been improved by using the compensations of space time block coding and Discrete Fast Fourier transforms (FFT or Discrete Wavelets transform DWT. These MC-DS-CDMA systems had been simulated using MATLAB 2015a. Through simulation of the proposed system, various parameters can be changed and tested. The Bit Error Rate (BERs of these systems are obtained over wide range of signal to noise ratio. All simulation results had been compared with each other using different subcarrier size of FFT or DWT with STBC for 1,2,3 and 4 antennas in transmitter and under different ITU multipath fading channels and different Doppler frequencies (fd. The proposed structures of STBC-MC-DS-CDMA system based on (DWT batter than based on (FFT in varies Doppler frequencies and subcarrier size. Also, proposed system with STBC based on 4 transmitters better than other systems based on 1 or 2 or 3 transmitters in all Doppler frequencies and subcarrier size in all simulation results.

Modeling and Analysis of Cellular CDMA Forward Channel

National Research Council Canada - National Science Library

Tighe, Jan

2001-01-01

In this thesis, we develop the forward channel model for a DS-CDMA cellular system operating in a slow-flat Rayleigh fading and log normal shadowing environment, which incorporates the extended Hata...

Experimental Performance Analysis of Wireless Links for Healthcare ...

African Journals Online (AJOL)

Wireless networking is currently being deployed for various applications. However, the application of wireless networking in healthcare remains a challenge mainly because of security and reliability concerns. This paper presents experimental results of performance analysis of a wireless network for healthcare application ...

Characterizing CDMA downlink feasibility via effective interference

NARCIS (Netherlands)

Endrayanto, A.I.; van den Berg, Hans Leo; Boucherie, Richardus J.

2003-01-01

This paper models and analyses downlink power assignment feasibility in Code Division Multiple Access (CDMA) mobile networks. By discretizing the area into small segments, the power requirements are characterized via a matrix representation that separates user and system characteristics. We obtain a

Distributed and Cooperative Link Scheduling for Large-Scale Multihop Wireless Networks

Directory of Open Access Journals (Sweden)

Swami Ananthram

2007-01-01

Full Text Available A distributed and cooperative link-scheduling (DCLS algorithm is introduced for large-scale multihop wireless networks. With this algorithm, each and every active link in the network cooperatively calibrates its environment and converges to a desired link schedule for data transmissions within a time frame of multiple slots. This schedule is such that the entire network is partitioned into a set of interleaved subnetworks, where each subnetwork consists of concurrent cochannel links that are properly separated from each other. The desired spacing in each subnetwork can be controlled by a tuning parameter and the number of time slots specified for each frame. Following the DCLS algorithm, a distributed and cooperative power control (DCPC algorithm can be applied to each subnetwork to ensure a desired data rate for each link with minimum network transmission power. As shown consistently by simulations, the DCLS algorithm along with a DCPC algorithm yields significant power savings. The power savings also imply an increased feasible region of averaged link data rates for the entire network.

Distributed and Cooperative Link Scheduling for Large-Scale Multihop Wireless Networks

Directory of Open Access Journals (Sweden)

Ananthram Swami

2007-12-01

Full Text Available A distributed and cooperative link-scheduling (DCLS algorithm is introduced for large-scale multihop wireless networks. With this algorithm, each and every active link in the network cooperatively calibrates its environment and converges to a desired link schedule for data transmissions within a time frame of multiple slots. This schedule is such that the entire network is partitioned into a set of interleaved subnetworks, where each subnetwork consists of concurrent cochannel links that are properly separated from each other. The desired spacing in each subnetwork can be controlled by a tuning parameter and the number of time slots specified for each frame. Following the DCLS algorithm, a distributed and cooperative power control (DCPC algorithm can be applied to each subnetwork to ensure a desired data rate for each link with minimum network transmission power. As shown consistently by simulations, the DCLS algorithm along with a DCPC algorithm yields significant power savings. The power savings also imply an increased feasible region of averaged link data rates for the entire network.

Rotated Walsh-Hadamard Spreading with Robust Channel Estimation for a Coded MC-CDMA System

Directory of Open Access Journals (Sweden)

Raulefs Ronald

2004-01-01

Full Text Available We investigate rotated Walsh-Hadamard spreading matrices for a broadband MC-CDMA system with robust channel estimation in the synchronous downlink. The similarities between rotated spreading and signal space diversity are outlined. In a multiuser MC-CDMA system, possible performance improvements are based on the chosen detector, the channel code, and its Hamming distance. By applying rotated spreading in comparison to a standard Walsh-Hadamard spreading code, a higher throughput can be achieved. As combining the channel code and the spreading code forms a concatenated code, the overall minimum Hamming distance of the concatenated code increases. This asymptotically results in an improvement of the bit error rate for high signal-to-noise ratio. Higher convolutional channel code rates are mostly generated by puncturing good low-rate channel codes. The overall Hamming distance decreases significantly for the punctured channel codes. Higher channel code rates are favorable for MC-CDMA, as MC-CDMA utilizes diversity more efficiently compared to pure OFDMA. The application of rotated spreading in an MC-CDMA system allows exploiting diversity even further. We demonstrate that the rotated spreading gain is still present for a robust pilot-aided channel estimator. In a well-designed system, rotated spreading extends the performance by using a maximum likelihood detector with robust channel estimation at the receiver by about 1 dB.

Bit Error Rate Analysis for MC-CDMA Systems in Nakagami- Fading Channels

Directory of Open Access Journals (Sweden)

Li Zexian

2004-01-01

Full Text Available Multicarrier code division multiple access (MC-CDMA is a promising technique that combines orthogonal frequency division multiplexing (OFDM with CDMA. In this paper, based on an alternative expression for the -function, characteristic function and Gaussian approximation, we present a new practical technique for determining the bit error rate (BER of multiuser MC-CDMA systems in frequency-selective Nakagami- fading channels. The results are applicable to systems employing coherent demodulation with maximal ratio combining (MRC or equal gain combining (EGC. The analysis assumes that different subcarriers experience independent fading channels, which are not necessarily identically distributed. The final average BER is expressed in the form of a single finite range integral and an integrand composed of tabulated functions which can be easily computed numerically. The accuracy of the proposed approach is demonstrated with computer simulations.

Space-Time Chip Equalization for Maximum Diversity Space-Time Block Coded DS-CDMA Downlink Transmission

Directory of Open Access Journals (Sweden)

Petré Frederik

2004-01-01

Full Text Available In the downlink of DS-CDMA, frequency-selectivity destroys the orthogonality of the user signals and introduces multiuser interference (MUI. Space-time chip equalization is an efficient tool to restore the orthogonality of the user signals and suppress the MUI. Furthermore, multiple-input multiple-output (MIMO communication techniques can result in a significant increase in capacity. This paper focuses on space-time block coding (STBC techniques, and aims at combining STBC techniques with the original single-antenna DS-CDMA downlink scheme. This results into the so-called space-time block coded DS-CDMA downlink schemes, many of which have been presented in the past. We focus on a new scheme that enables both the maximum multiantenna diversity and the maximum multipath diversity. Although this maximum diversity can only be collected by maximum likelihood (ML detection, we pursue suboptimal detection by means of space-time chip equalization, which lowers the computational complexity significantly. To design the space-time chip equalizers, we also propose efficient pilot-based methods. Simulation results show improved performance over the space-time RAKE receiver for the space-time block coded DS-CDMA downlink schemes that have been proposed for the UMTS and IS-2000 W-CDMA standards.

Distortion-Based Link Adaptation for Wireless Video Transmission

Directory of Open Access Journals (Sweden)

Andrew Nix

2008-06-01

Full Text Available Wireless local area networks (WLANs such as IEEE 802.11a/g utilise numerous transmission modes, each providing different throughputs and reliability levels. Most link adaptation algorithms proposed in the literature (i maximise the error-free data throughput, (ii do not take into account the content of the data stream, and (iii rely strongly on the use of ARQ. Low-latency applications, such as real-time video transmission, do not permit large numbers of retransmission. In this paper, a novel link adaptation scheme is presented that improves the quality of service (QoS for video transmission. Rather than maximising the error-free throughput, our scheme minimises the video distortion of the received sequence. With the use of simple and local rate distortion measures and end-to-end distortion models at the video encoder, the proposed scheme estimates the received video distortion at the current transmission rate, as well as on the adjacent lower and higher rates. This allows the system to select the link-speed which offers the lowest distortion and to adapt to the channel conditions. Simulation results are presented using the MPEG-4/AVC H.264 video compression standard over IEEE 802.11g. The results show that the proposed system closely follows the optimum theoretic solution.

Wireless mesh networks.

Science.gov (United States)

Wang, Xinheng

2008-01-01

Wireless telemedicine using GSM and GPRS technologies can only provide low bandwidth connections, which makes it difficult to transmit images and video. Satellite or 3G wireless transmission provides greater bandwidth, but the running costs are high. Wireless networks (WLANs) appear promising, since they can supply high bandwidth at low cost. However, the WLAN technology has limitations, such as coverage. A new wireless networking technology named the wireless mesh network (WMN) overcomes some of the limitations of the WLAN. A WMN combines the characteristics of both a WLAN and ad hoc networks, thus forming an intelligent, large scale and broadband wireless network. These features are attractive for telemedicine and telecare because of the ability to provide data, voice and video communications over a large area. One successful wireless telemedicine project which uses wireless mesh technology is the Emergency Room Link (ER-LINK) in Tucson, Arizona, USA. There are three key characteristics of a WMN: self-organization, including self-management and self-healing; dynamic changes in network topology; and scalability. What we may now see is a shift from mobile communication and satellite systems for wireless telemedicine to the use of wireless networks based on mesh technology, since the latter are very attractive in terms of cost, reliability and speed.

Bandwidth enhancement of wireless optical communication link using a near-infrared laser over turbid underwater channel

KAUST Repository

Lee, It Ee; Guo, Yujian; Ng, Tien Khee; Park, Kihong; Alouini, Mohamed-Slim; Ooi, Boon S.

2017-01-01

Underwater wireless optical communication (UWOC) has been widely studied as a promising alternative to establish reliable short-range marine communication links. Microscopic particulates suspended in various ocean, harbor and natural waters

80 Gbit/s 16-QAM Multicarrier THz Wireless Communication Link in the 400 GHz Band

DEFF Research Database (Denmark)

Jia, Shi; Yu, Xianbin; Hu, Hao

2016-01-01

We experimentally demonstrate a high-speed multicarrier THz wireless communication system operating in the 400 GHz band. The use of spectrally efficient 16-QAM modulation and broadband THz transceivers enable link data rates up to 80 Gbit/s....

Fiber-wireless transmission system of 108  Gb/sdata over 80 km fiber and 2×2multiple-input multiple-output wireless links at 100 GHz W-band frequency.

Science.gov (United States)

Li, Xinying; Dong, Ze; Yu, Jianjun; Chi, Nan; Shao, Yufeng; Chang, G K

2012-12-15

We experimentally demonstrate a seamlessly integrated fiber-wireless system that delivers a 108  Gb/s signal through 80 km fiber and 1 m wireless transport over free space at 100 GHz adopting polarization-division-multiplexing quadrature-phase-shift-keying (PDM-QPSK) modulation and heterodyning coherent detection. The X- and Y-polarization components of the optical PDM-QPSK baseband signal are simultaneously upconverted to 100 GHz wireless carrier by optical polarization-diversity heterodyne beating, and then independently transmitted and received by two pairs of transmitter and receiver antennas, which form a 2×2 multiple-input multiple-output wireless link. At the wireless receiver, two-stage downconversion is performed firstly in the analog domain based on balanced mixer and sinusoidal radio frequency signal, and then in the digital domain based on digital signal processing (DSP). Polarization demultiplexing is realized by the constant modulus algorithm in the DSP part at the receiver. The bit-error ratio for the 108  Gb/s PDM-QPSK signal is less than the pre-forward-error-correction threshold of 3.8×10(-3) after both 1 m wireless delivery at 100 GHz and 80 km single-mode fiber-28 transmission. To our knowledge, this is the first demonstration to realize 100  Gb/s signal delivery through both fiber and wireless links at 100 GHz.

Channel coding for underwater acoustic single-carrier CDMA communication system

Science.gov (United States)

Liu, Lanjun; Zhang, Yonglei; Zhang, Pengcheng; Zhou, Lin; Niu, Jiong

2017-01-01

CDMA is an effective multiple access protocol for underwater acoustic networks, and channel coding can effectively reduce the bit error rate (BER) of the underwater acoustic communication system. For the requirements of underwater acoustic mobile networks based on CDMA, an underwater acoustic single-carrier CDMA communication system (UWA/SCCDMA) based on the direct-sequence spread spectrum is proposed, and its channel coding scheme is studied based on convolution, RA, Turbo and LDPC coding respectively. The implementation steps of the Viterbi algorithm of convolutional coding, BP and minimum sum algorithms of RA coding, Log-MAP and SOVA algorithms of Turbo coding, and sum-product algorithm of LDPC coding are given. An UWA/SCCDMA simulation system based on Matlab is designed. Simulation results show that the UWA/SCCDMA based on RA, Turbo and LDPC coding have good performance such that the communication BER is all less than 10-6 in the underwater acoustic channel with low signal to noise ratio (SNR) from -12 dB to -10dB, which is about 2 orders of magnitude lower than that of the convolutional coding. The system based on Turbo coding with Log-MAP algorithm has the best performance.

16 Gb/s QPSK Wireless-over-Fibre Link in 75-110GHz Band Employing Optical Heterodyne Generation and Coherent Detection

DEFF Research Database (Denmark)

Zibar, Darko; Sambaraju, Rakesh; Caballero Jambrina, Antonio

2010-01-01

We report on the first demonstration of QPSK based Wireless-over-Fibre link in 75-110GHz band with a record capacity of up to 16Gb/s. Photonic wireless signal generation by heterodyne beating of free-running lasers and baud-rate digital coherent detection are employed....

BER Performance Simulation of Generalized MC DS-CDMA System with Time-Limited Blackman Chip Waveform

Directory of Open Access Journals (Sweden)

I. Develi

2010-09-01

Full Text Available Multiple access interference encountered in multicarrier direct sequence-code division multiple access (MC DS-CDMA is the most important difficulty that depends mainly on the correlation properties of the spreading sequences as well as the shape of the chip waveforms employed. In this paper, bit error rate (BER performance of the generalized MC DS-CDMA system that employs time-limited Blackman chip waveform is presented for Nakagami-m fading channels. Simulation results show that the use of Blackman chip waveform can improve the BER performance of the generalized MC DS-CDMA system, as compared to the performances achieved by using timelimited chip waveforms in the literature.

Impact of a half-space interface on the wireless link between tiny sensor nodes

NARCIS (Netherlands)

Penkin, D.; Janssen, G.; Yarovoy, A.

2014-01-01

The power budget of a wireless link between two electrically small sensor nodes located close to an interface between two media is studied. The model includes both the propagation channel losses and input impedance of the radio frequency antennas. It is shown that a highly inductive half-space

Pilot power based rate control in CDMA 2000 1x EV-DO Rev-A

Institute of Scientific and Technical Information of China (English)

LIU Xiao-feng; GU Jian; YANG Hong-wen

2008-01-01

This article proposes a new algorithm to improvethe rate control efficiency of enhanced reverse link mediumaccess control (RLMAC) in the code division multiple access(CDMA) lx EV-DO release A(Rev. A) system. The newalgorithm brings reverse access terminal (AT) pilot power tothe RLMAC rate control procedure and makes it easier for alow pilot power user to increase its data rate when the systemis slightly loaded and harder to decrease its date rate when thesystem is heavily loaded. Numerical results of system levelsimulations show that the new algorithm can bring highersystem throughput, lower AT transmission power, and lowersystem load.

Particle Filtering for Multiple Access DS/CDMA Systems DS/CDMA Channel Estimation

Directory of Open Access Journals (Sweden)

Rafael Oliveira Ribeiro

2013-09-01

Full Text Available This article discusses computational implementation aspects and performance of a Bayesian methodology, namely particle filter (PF. The PF channel estimation technique is directly applied to the channel coefficients estimation of DS/CDMA systems. Simulation results for non-line-of-sight (NLOS Rayleigh fading channel propagation have indicated that the bootstrap PF estimator is capable to provide RMSE in the range of [10-3 ; 10-2] for a wide range of multiple access interference (MAI levels and signal-noise ratio (SNR, and still be able to offer robustness to near-far ratio (NFR effect.

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

Institute of Scientific and Technical Information of China (English)

无

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.

Opportunities and challenges for optical wireless: the competitive advantage of free space telecommunications links in today's crowded marketplace

Science.gov (United States)

Carbonneau, Theresa H.; Wisely, David R.

1998-01-01

Never before has the opportunity for terrestrial optical wireless communications links been so great. The high data rates attainable, up to OC-24, make it a very attractive and cost effective alternative to traditional fiber optic and microwave links. With today's demand for interactive multimedia-based applications, such as video conferencing and telemedicine, optical wireless products are the only ones that can provide the needed bandwidth in situations when it is too costly or impossible to install fiber optic cable. Recent developments in laser and optics technologies, in addition to auto beam tracking, permit transmission units to achieve excellent performance rates in all weather conditions.

Digital Photonic Receivers for Wireless and Wireline Optical Fiber Transmission Links

DEFF Research Database (Denmark)

Guerrero Gonzalez, Neil

services. The experimental demonstration supported the following transmissions systems: a baseband, 5 Gbps, intensity modulation system employing a directly modulated vertical cavity surface emitting laser (VCSEL), a baseband 20 Gbps non-return-to-zero quadrature phase-shift keying (NRZ-QPSK) system...... receivers in hybrid wireless and wireline optical fiber transmission links. Furthermore, the digital signal processing framework presented in this thesis can be extended to design probabilistic-based digital photonic receivers that can find applications in cognitive heterogeneous reconfigurable optical...

Super-Orthogonal Space-Time Turbo Transmit Diversity for CDMA

Directory of Open Access Journals (Sweden)

Pieter G. W. van Rooyen

2005-05-01

Full Text Available Studies have shown that transmit and receive diversity employing a combination of multiple transmit-receive antennas (given ideal channel state information (CSI and independent fading between antenna pairs will potentially yield maximum achievable system capacity. In this paper, the concept of a layered super-orthogonal turbo transmit diversity (SOTTD for downlink direct-sequence code-division multiple-access (CDMA systems is explored. This open-loop transmit diversity technique improves the downlink performance by using a small number of antenna elements at the base station and a single antenna at the handset. In the proposed technique, low-rate super-orthogonal code-spread CDMA is married with code-division transmit diversity (CDTD. At the mobile receiver, space-time (ST RAKE CDTD processing is combined with iterative turbo code-spread decoding to yield large ST gains. The performance of the SOTTD system is compared with single- and multiantenna turbo-coded (TC CDTD systems evaluated over a frequency-selective Rayleigh fading channel. The evaluation is done both by means of analysis and computer simulations. The performance results illustrate the superior performance of SOTTD compared to TC CDTD systems over practically the complete useful capacity range of CDMA. It is shown that the performance degradation characteristic of TC CDTD at low system loads (due to the inherent TC error floor is alleviated by the SOTTD system.

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...

Frequency-division multiplexer and demultiplexer for terahertz wireless links.

Science.gov (United States)

Ma, Jianjun; Karl, Nicholas J; Bretin, Sara; Ducournau, Guillaume; Mittleman, Daniel M

2017-09-28

The development of components for terahertz wireless communications networks has become an active and growing research field. However, in most cases these components have been studied using a continuous or broadband-pulsed terahertz source, not using a modulated data stream. This limitation may mask important aspects of the performance of the device in a realistic system configuration. We report the characterization of one such device, a frequency multiplexer, using modulated data at rates up to 10 gigabits per second. We also demonstrate simultaneous error-free transmission of two signals at different carrier frequencies, with an aggregate data rate of 50 gigabits per second. We observe that the far-field spatial variation of the bit error rate is different from that of the emitted power, due to a small nonuniformity in the angular detection sensitivity. This is likely to be a common feature of any terahertz communication system in which signals propagate as diffracting beams not omnidirectional broadcasts.There is growing interest in the development of components to facilitate wireless communications in the terahertz but the characterization of these systems involve an unmodulated input. Here the authors demonstrate multiplexing and demultiplexing of data streams in the terahertz range using a real data link.

Link-state-estimation-based transmission power control in wireless body area networks.

Science.gov (United States)

Kim, Seungku; Eom, Doo-Seop

2014-07-01

This paper presents a novel transmission power control protocol to extend the lifetime of sensor nodes and to increase the link reliability in wireless body area networks (WBANs). We first experimentally investigate the properties of the link states using the received signal strength indicator (RSSI). We then propose a practical transmission power control protocol based on both short- and long-term link-state estimations. Both the short- and long-term link-state estimations enable the transceiver to adapt the transmission power level and target the RSSI threshold range, respectively, to simultaneously satisfy the requirements of energy efficiency and link reliability. Finally, the performance of the proposed protocol is experimentally evaluated in two experimental scenarios-body posture change and dynamic body motion-and compared with the typical WBAN transmission power control protocols, a real-time reactive scheme, and a dynamic postural position inference mechanism. From the experimental results, it is found that the proposed protocol increases the lifetime of the sensor nodes by a maximum of 9.86% and enhances the link reliability by reducing the packet loss by a maximum of 3.02%.

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.

Pilot-Assisted Channel Estimation for Orthogonal Multi-Carrier DS-CDMA with Frequency-Domain Equalization

Science.gov (United States)

Shima, Tomoyuki; Tomeba, Hiromichi; Adachi, Fumiyuki

Orthogonal multi-carrier direct sequence code division multiple access (orthogonal MC DS-CDMA) is a combination of time-domain spreading and orthogonal frequency division multiplexing (OFDM). In orthogonal MC DS-CDMA, the frequency diversity gain can be obtained by applying frequency-domain equalization (FDE) based on minimum mean square error (MMSE) criterion to a block of OFDM symbols and can improve the bit error rate (BER) performance in a severe frequency-selective fading channel. FDE requires an accurate estimate of the channel gain. The channel gain can be estimated by removing the pilot modulation in the frequency domain. In this paper, we propose a pilot-assisted channel estimation suitable for orthogonal MC DS-CDMA with FDE and evaluate, by computer simulation, the BER performance in a frequency-selective Rayleigh fading channel.

Novel Concepts of Cooperative Wireless Networking

DEFF Research Database (Denmark)

Zhang, Qi

2008-01-01

; secondly, the increasing density of the wireless devices makes cooperation possible; last, the cost of information exchange (i.e. transmission power, transmission time, spectrum, etc.) is very low if information exchange over short-range link is needed. Cooperation changes the way of information delivery......Although wireless networks have achieved great success in the lastest two decades, the current wireless networks have difficulties to fulll users' ever-increasing expectations and needs. It is mainly due to available spectrum resource scarcity, limited battery capacity of wireless device......, unreliable wireless radio link, etc. To tackle these issues, a new telecommunication paradigm has been proposed, referred to as cooperative wireless networking [1]. The basic idea of cooperative wireless networking is that wireless devices work together to achieve their individual goals or one common goal...

Characterization of In-Body to On-Body Wireless Radio Frequency Link for Upper Limb Prostheses.

Directory of Open Access Journals (Sweden)

Antonietta Stango

Full Text Available Wireless implanted devices can be used to interface patients with disabilities with the aim of restoring impaired motor functions. Implanted devices that record and transmit electromyographic (EMG signals have been applied for the control of active prostheses. This simulation study investigates the propagation losses and the absorption rate of a wireless radio frequency link for in-to-on body communication in the medical implant communication service (MICS frequency band to control myoelectric upper limb prostheses. The implanted antenna is selected and a suitable external antenna is designed. The characterization of both antennas is done by numerical simulations. A heterogeneous 3D body model and a 3D electromagnetic solver have been used to model the path loss and to characterize the specific absorption rate (SAR. The path loss parameters were extracted and the SAR was characterized, verifying the compliance with the guideline limits. The path loss model has been also used for a preliminary link budget analysis to determine the feasibility of such system compliant with the IEEE 802.15.6 standard. The resulting link margin of 11 dB confirms the feasibility of the system proposed.

Rapid Industrial Prototyping and SoC Design of 3G/4G Wireless Systems Using an HLS Methodology

Directory of Open Access Journals (Sweden)

Andres Takach

2006-07-01

Full Text Available Many very-high-complexity signal processing algorithms are required in future wireless systems, giving tremendous challenges to real-time implementations. In this paper, we present our industrial rapid prototyping experiences on 3G/4G wireless systems using advanced signal processing algorithms in MIMO-CDMA and MIMO-OFDM systems. Core system design issues are studied and advanced receiver algorithms suitable for implementation are proposed for synchronization, MIMO equalization, and detection. We then present VLSI-oriented complexity reduction schemes and demonstrate how to interact these high-complexity algorithms with an HLS-based methodology for extensive design space exploration. This is achieved by abstracting the main effort from hardware iterations to the algorithmic C/C++ fixed-point design. We also analyze the advantages and limitations of the methodology. Our industrial design experience demonstrates that it is possible to enable an extensive architectural analysis in a short-time frame using HLS methodology, which significantly shortens the time to market for wireless systems.

Rapid Industrial Prototyping and SoC Design of 3G/4G Wireless Systems Using an HLS Methodology

Directory of Open Access Journals (Sweden)

Cavallaro JosephR

2006-01-01

Full Text Available Many very-high-complexity signal processing algorithms are required in future wireless systems, giving tremendous challenges to real-time implementations. In this paper, we present our industrial rapid prototyping experiences on 3G/4G wireless systems using advanced signal processing algorithms in MIMO-CDMA and MIMO-OFDM systems. Core system design issues are studied and advanced receiver algorithms suitable for implementation are proposed for synchronization, MIMO equalization, and detection. We then present VLSI-oriented complexity reduction schemes and demonstrate how to interact these high-complexity algorithms with an HLS-based methodology for extensive design space exploration. This is achieved by abstracting the main effort from hardware iterations to the algorithmic C/C++ fixed-point design. We also analyze the advantages and limitations of the methodology. Our industrial design experience demonstrates that it is possible to enable an extensive architectural analysis in a short-time frame using HLS methodology, which significantly shortens the time to market for wireless systems.

Joint Transmitter-Receiver Optimization in the Downlink CDMA Systems

Directory of Open Access Journals (Sweden)

Mohammad Saquib

2002-08-01

Full Text Available To maximize the downlink code-division multiple access (CDMA system capacity, we propose to minimize the total transmitted power of the system subject to users′ signal-to-interference ratio (SIR requirements via designing optimum transmitter sequences and utilizing linear optimum receivers (minimum mean square error (MMSE receiver. In our work on joint transmitter-receiver design for the downlink CDMA systems with multiple antennas and multipath channels, we develop several optimization algorithms by considering various system constraints and prove their convergence. We empirically observed that under the optimization algorithm with no constraint on the system, the optimum receiver structure matches the received transmitter sequences. A simulation study is performed to see how the different practical system constraints penalize the system with respect to the optimum algorithm with no constraint on the system.

GLONASS CDMA L3 ambiguity resolution and positioning

NARCIS (Netherlands)

Zaminpardaz, Safoora; Teunissen, P.J.G.; Nadarajah, Nandakumaran

2016-01-01

A first assessment of GLONASS CDMA L3 ambiguity resolution and positioning performance is provided. Our analyses are based on GLONASS L3 data from the satellite pair SVNs 755-801, received by two JAVAD receivers at Curtin University, Perth, Australia. In our analyses, four different versions of

An asymmetric resonant coupling wireless power transmission link for Micro-Ball Endoscopy.

Science.gov (United States)

Sun, Tianjia; Xie, Xiang; Li, Guolin; Gu, Yingke; Deng, Yangdong; Wang, Ziqiang; Wang, Zhihua

2010-01-01

This paper investigates the design and optimization of a wireless power transmission link targeting Micro-Ball Endoscopy applications. A novel asymmetric resonant coupling structure is proposed to deliver power to an endoscopic Micro-Ball system for image read-out after it is excreted. Such a technology enables many key medical applications with stringent requirements for small system volume and high power delivery efficiency. A prototyping power transmission sub-system of the Micro-Ball system was implemented. It consists of primary coil, middle resonant coil, and cube-like full-direction secondary receiving coils. Our experimental results proved that 200mW of power can be successfully delivered. Such a wireless power transmission capability could satisfy the requirements of the Micro-Ball based endoscopy application. The transmission efficiency is in the range of 41% (worst working condition) to 53% (best working condition). Comparing to conventional structures, Asymmetric Resonant Coupling Structure improves power efficiency by 13%.

A combinatorial approximation algorithm for CDMA downlink rate allocation

NARCIS (Netherlands)

Boucherie, Richardus J.; Bumb, A.F.; Endrayanto, A.I.; Woeginger, Gerhard; Raghavan, S.; Anandalingam, G.

2006-01-01

This paper presents a combinatorial algorithm for downlink rate allocation in Code Division Multiple Access (CDMA) mobile networks. By discretizing the coverage area into small segments, the transmit power requirements are characterized via a matrix representation that separates user and system

A combinatorial approximation algorithm for CDMA downlink rate allocation

NARCIS (Netherlands)

Boucherie, Richardus J.; Bumb, A.F.; Endrayanto, A.I.; Woeginger, Gerhard

2004-01-01

This paper presents a combinatorial algorithm for downlink rate allocation in Code Division Multiple Access (CDMA) mobile networks. By discretizing the coverage area into small segments, the transmit power requirements are characterized via a matrix representation that separates user and system

Cross-Layer Admission Control Policy for CDMA Beamforming Systems

Directory of Open Access Journals (Sweden)

Sheng Wei

2007-01-01

Full Text Available A novel admission control (AC policy is proposed for the uplink of a cellular CDMA beamforming system. An approximated power control feasibility condition (PCFC, required by a cross-layer AC policy, is derived. This approximation, however, increases outage probability in the physical layer. A truncated automatic retransmission request (ARQ scheme is then employed to mitigate the outage problem. In this paper, we investigate the joint design of an AC policy and an ARQ-based outage mitigation algorithm in a cross-layer context. This paper provides a framework for joint AC design among physical, data-link, and network layers. This enables multiple quality-of-service (QoS requirements to be more flexibly used to optimize system performance. Numerical examples show that by appropriately choosing ARQ parameters, the proposed AC policy can achieve a significant performance gain in terms of reduced outage probability and increased system throughput, while simultaneously guaranteeing all the QoS requirements.

A satellite mobile communication system based on Band-Limited Quasi-Synchronous Code Division Multiple Access (BLQS-CDMA)

Science.gov (United States)

Degaudenzi, R.; Elia, C.; Viola, R.

1990-01-01

Discussed here is a new approach to code division multiple access applied to a mobile system for voice (and data) services based on Band Limited Quasi Synchronous Code Division Multiple Access (BLQS-CDMA). The system requires users to be chip synchronized to reduce the contribution of self-interference and to make use of voice activation in order to increase the satellite power efficiency. In order to achieve spectral efficiency, Nyquist chip pulse shaping is used with no detection performance impairment. The synchronization problems are solved in the forward link by distributing a master code, whereas carrier forced activation and closed loop control techniques have been adopted in the return link. System performance sensitivity to nonlinear amplification and timing/frequency synchronization errors are analyzed.

Compact wideband CMOS receiver frontends for wireless communication

NARCIS (Netherlands)

Blaakmeer, S.C.

2010-01-01

Abstract Wireless communication is an integral part of our daily life, the mobile phone is an example of a very popular wireless communication device. A communication link consists of a transmitter, a receiver and the transmission medium, which air or vacuum for a wireless link. Part of the receiver

On capacity tradeoffs in secure DS-CDMA packet communications with QOS constraints

International Nuclear Information System (INIS)

Sattar, F.; Mufti, M.

2012-01-01

This paper presents a mathematical framework for analysis of effect of counter mode (CTR) encryption on the traffic capacity of packet communication systems based on direct-sequence, code-division, multiple-access (DS-CDMA). We specify QoS constraints in terms of minimum acceptable mean opinion score (MOS) of voice payload, maximum permissible resource utilization for CTR-mode re-keying and DS-CDMA processing gain. We quantify the trade-offs in system capacity as a function of these constraints. Results show that application of CTR encryption causes error expansion and respecting the QoS constraints while satisfying the desired encryption parameters results in reduction of traffic capacity. (author)

Comparison and classification of all-optical CDMA systems for future telecommunication networks

Science.gov (United States)

Iversen, Kay; Hampicke, Dirk

1995-12-01

This paper shows the state of the art in fiber optical code-division multiple-access (CDMA). Recent work in this area for both, systems and sequences is reviewed and analyzed. For that purpose a classification of systems, corresponding to the manner of signal processing and a classification of known (0,1)-sequences are presented. It is shown that due to the limits by currently available device technology especially two techniques are promising for implementation in broadband telecommunication networks: spectral encoding with integrated optical filters and CDMA in combination with wavelength multiple access schemes. Further an overview about some important experiments in this field is given.

Symmetric Link Key Management for Secure Neighbor Discovery in a Decentralized Wireless Sensor Network

Science.gov (United States)

2017-09-01

KEY MANAGEMENT FOR SECURE NEIGHBOR DISCOVERY IN A DECENTRALIZED WIRELESS SENSOR NETWORK by Kelvin T. Chew September 2017 Thesis Advisor...and to the Office of Management and Budget, Paperwork Reduction Project (0704-0188) Washington, DC 20503. 1. AGENCY USE ONLY (Leave blank) 2. REPORT...DATE September 2017 3. REPORT TYPE AND DATES COVERED Master’s thesis 4. TITLE AND SUBTITLE SYMMETRIC LINK KEY MANAGEMENT FOR SECURE NEIGHBOR

The Wireless ATM Architecture

Directory of Open Access Journals (Sweden)

R. Palitefka

1998-06-01

Full Text Available An overview of the proposed wireless ATM structure is provided. Wireless communication have been developed to a level where offered services can now be extended beyond voice and data. There are already wireless LANs, cordless systems offering data services and mobile data. Wireless LAN systems are basically planned for local, on-promises and in-house networking providing short distance radio or infrared links between computer system. The main challenge of wireless ATM is to harmonise the development of broadband wireless system with service B -ISDN/ATM and ATM LANs, and offer multimedia multiservice features for the support of time-sensitive voice communication, video, desktop multimedia applications, and LAN data traffic for the wireless user.

Introduction to wireless sensor networks

CERN Document Server

Forster, Anna

2016-01-01

Explores real-world wireless sensor network development, deployment, and applications. The book begins with an introduction to wireless sensor networks and their fundamental concepts. Hardware components, operating systems, protocols, and algorithms that make up the anatomy of a sensor node are described in chapter two. Properties of wireless communications, medium access protocols, wireless links, and link estimation protocols are described in chapter three and chapter four. Routing basics and metrics, clustering techniques, time synchronization and localization protocols, as well as sensing techniques are introduced in chapter five to nine. The concluding chapter summarizes the learnt methods and shows how to use them to deploy real-world sensor networks in a structured way.

Wireless coexistence and interference test method for low-power wireless sensor networks

NARCIS (Netherlands)

Serra, R.; Nabi, Majid

2015-01-01

Wireless sensor networks (WSNs) are being increasingly introduced for critical applications such as safety, security and health. One the main characteristic requirements of such networks are that they should function with relative low power. Therefore the wireless links are more vulnerable.

An Iterative Multiuser Detector for Turbo-Coded DS-CDMA Systems

Directory of Open Access Journals (Sweden)

Takawira Fambirai

2005-01-01

Full Text Available We propose an iterative multiuser detector for turbo-coded synchronous and asynchronous direct-sequence CDMA (DS-CDMA systems. The receiver is derived from the maximum a posteriori (MAP estimation of the single user's transmitted data, conditioned on information about the estimate of the multiple-access interference (MAI and the received signal from the channel. This multiple-access interference is reconstructed by making hard decisions on the users' detected bits at the preceding iteration. The complexity of the proposed receiver increases linearly with the number of users. The proposed detection scheme is compared with a previously developed one. The multiuser detector proposed in this paper has a better performance when the transmitted powers of all active users are equal in the additive white Gaussian noise (AWGN channel. Also, the detector is found to be resilient against the near-far effect.

Wireless sensor networks architectures and protocols

CERN Document Server

Callaway, Jr, Edgar H

2003-01-01

Introduction to Wireless Sensor NetworksApplications and MotivationNetwork Performance ObjectivesContributions of this BookOrganization of this BookThe Development of Wireless Sensor NetworksEarly Wireless NetworksWireless Data NetworksWireless Sensor and Related NetworksConclusionThe Physical LayerSome Physical Layer ExamplesA Practical Physical Layer for Wireless Sensor NetworksSimulations and ResultsConclusionThe Data Link LayerMedium Access Control TechniquesThe Mediation DeviceSystem Analysis and SimulationConclusionThe Network LayerSome Network Design ExamplesA Wireless Sensor Network De

A Game Theoretic Optimization Method for Energy Efficient Global Connectivity in Hybrid Wireless Sensor Networks

Directory of Open Access Journals (Sweden)

JongHyup Lee

2016-08-01

Full Text Available For practical deployment of wireless sensor networks (WSN, WSNs construct clusters, where a sensor node communicates with other nodes in its cluster, and a cluster head support connectivity between the sensor nodes and a sink node. In hybrid WSNs, cluster heads have cellular network interfaces for global connectivity. However, when WSNs are active and the load of cellular networks is high, the optimal assignment of cluster heads to base stations becomes critical. Therefore, in this paper, we propose a game theoretic model to find the optimal assignment of base stations for hybrid WSNs. Since the communication and energy cost is different according to cellular systems, we devise two game models for TDMA/FDMA and CDMA systems employing power prices to adapt to the varying efficiency of recent wireless technologies. The proposed model is defined on the assumptions of the ideal sensing field, but our evaluation shows that the proposed model is more adaptive and energy efficient than local selections.

A Game Theoretic Optimization Method for Energy Efficient Global Connectivity in Hybrid Wireless Sensor Networks

Science.gov (United States)

Lee, JongHyup; Pak, Dohyun

2016-01-01

For practical deployment of wireless sensor networks (WSN), WSNs construct clusters, where a sensor node communicates with other nodes in its cluster, and a cluster head support connectivity between the sensor nodes and a sink node. In hybrid WSNs, cluster heads have cellular network interfaces for global connectivity. However, when WSNs are active and the load of cellular networks is high, the optimal assignment of cluster heads to base stations becomes critical. Therefore, in this paper, we propose a game theoretic model to find the optimal assignment of base stations for hybrid WSNs. Since the communication and energy cost is different according to cellular systems, we devise two game models for TDMA/FDMA and CDMA systems employing power prices to adapt to the varying efficiency of recent wireless technologies. The proposed model is defined on the assumptions of the ideal sensing field, but our evaluation shows that the proposed model is more adaptive and energy efficient than local selections. PMID:27589743

SOFT AND SOFTER HANDOVER PERFORMANCE OF CDMA

Directory of Open Access Journals (Sweden)

Lina wati

2010-12-01

Full Text Available One of telecommunication providers in Indonesia applies CDMA2000 1x technology. The technology hasmany advantages such as larger channel capacity of BTS (Base Transceiver Station. On the other hand, thecapacity depends on user’s density. Therefore to guarantee voice connection when user or mobile station (MS isalways moving from one cell to others, handover technique is needed. However the technique can be failed for manyreasons. Therefore impact of call attempt on softer and soft handover performance is investigated. Hence the paperexamined soft – softer handover performance of CDMA in BTS (Base Transceiver Station, BSC, and Sectors inboth sub-urban and rural areas in Denpasar, Bali with area code of 0361.The research has been done in rural and suburban area with call area code ‘0361’. The analyses includedregression and simple linear correlation applications. The results showed that number of call attempts affected thefailure of soft and softer handover technique dominantly. Generally, average level of success both handover in bothrural and suburban area were about 99% which are above KPI (Key Performance Indicator reference at 98.50%.However in rural area, other factors such as blocking called attempt and error called number have caused the softerhandover failure.

Statistical Analysis of Coherent Ultrashort Light Pulse CDMA With Multiple Optical Amplifiers Using Additive Noise Model

Science.gov (United States)

Jamshidi, Kambiz; Salehi, Jawad A.

2005-05-01

This paper describes a study of the performance of various configurations for placing multiple optical amplifiers in a typical coherent ultrashort light pulse code-division multiple access (CULP-CDMA) communication system using the additive noise model. For this study, a comprehensive performance analysis was developed that takes into account multiple-access noise, noise due to optical amplifiers, and thermal noise using the saddle-point approximation technique. Prior to obtaining the overall system performance, the input/output statistical models for different elements of the system such as encoders/decoders,star coupler, and optical amplifiers were obtained. Performance comparisons between an ideal and lossless quantum-limited case and a typical CULP-CDMA with various losses exhibit more than 30 dB more power requirement to obtain the same bit-error rate (BER). Considering the saturation effect of optical amplifiers, this paper discusses an algorithm for amplifiers' gain setting in various stages of the network in order to overcome the nonlinear effects on signal modulation in optical amplifiers. Finally, using this algorithm,various configurations of multiple optical amplifiers in CULP-CDMA are discussed and the rules for the required optimum number of amplifiers are shown with their corresponding optimum locations to be implemented along the CULP-CDMA system.

30-Gb/s bidirectional transparent optical transmission with an MMF access and an indoor optical wireless link

NARCIS (Netherlands)

Chen, H.; Boom, van den H.P.A.; Tangdiongga, E.; Koonen, A.M.J.

2012-01-01

This letter describes a 30-Gb/s bidirectional transparent optical transmission, over a 4.4-km multimode fiber (MMF) in combination with an indoor optical wireless (OW) link, which could provide limited mobility. Due to MMF's advantages, such as lower installation costs and easy maintenance, it is

Capacity and coverage of power controlled CDMA cellular systems ...

African Journals Online (AJOL)

Coverage and capacity are among the ambitious challenges to be met by the third generation (3G) systems for successful deployment of its services to both residential and commercial subscribers. This paper reports on the performance study of CDMA systems in relation to an optimum step-regulated SNR-based ...

20-meter underwater wireless optical communication link with 15 Gbps data rate

KAUST Repository

Shen, Chao

2016-10-24

The video streaming, data transmission, and remote control in underwater call for high speed (Gbps) communication link with a long channel length (∼10 meters). We present a compact and low power consumption underwater wireless optical communication (UWOC) system utilizing a 450-nm laser diode (LD) and a Si avalanche photodetector. With the LD operating at a driving current of 80 mA with an optical power of 51.3 mW, we demonstrated a high-speed UWOC link offering a data rate up to 2 Gbps over a 12-meter-long, and 1.5 Gbps over a record 20-meter-long underwater channel. The measured bit-error rate (BER) are 2.8 × 10-5, and 3.0 × 10-3, respectively, which pass well the forward error correction (FEC) criterion. © 2016 Optical Society of America.

20-meter underwater wireless optical communication link with 15 Gbps data rate

KAUST Repository

Shen, Chao; Guo, Yong; Oubei, Hassan M.; Ng, Tien Khee; Liu, Guangyu; Park, Kihong; Ho, Kang-Ting; Alouini, Mohamed-Slim; Ooi, Boon S.

2016-01-01

The video streaming, data transmission, and remote control in underwater call for high speed (Gbps) communication link with a long channel length (∼10 meters). We present a compact and low power consumption underwater wireless optical communication (UWOC) system utilizing a 450-nm laser diode (LD) and a Si avalanche photodetector. With the LD operating at a driving current of 80 mA with an optical power of 51.3 mW, we demonstrated a high-speed UWOC link offering a data rate up to 2 Gbps over a 12-meter-long, and 1.5 Gbps over a record 20-meter-long underwater channel. The measured bit-error rate (BER) are 2.8 × 10-5, and 3.0 × 10-3, respectively, which pass well the forward error correction (FEC) criterion. © 2016 Optical Society of America.

An Efficient Code-Timing Estimator for DS-CDMA Systems over Resolvable Multipath Channels

Directory of Open Access Journals (Sweden)

Jian Li

2005-04-01

Full Text Available We consider the problem of training-based code-timing estimation for the asynchronous direct-sequence code-division multiple-access (DS-CDMA system. We propose a modified large-sample maximum-likelihood (MLSML estimator that can be used for the code-timing estimation for the DS-CDMA systems over the resolvable multipath channels in closed form. Simulation results show that MLSML can be used to provide a high correct acquisition probability and a high estimation accuracy. Simulation results also show that MLSML can have very good near-far resistant capability due to employing a data model similar to that for adaptive array processing where strong interferences can be suppressed.

Investigation of interference in multiple-input multiple-output wireless transmission at W band for an optical wireless integration system.

Science.gov (United States)

Li, Xinying; Yu, Jianjun; Dong, Ze; Zhang, Junwen; Chi, Nan; Yu, Jianguo

2013-03-01

We experimentally investigate the interference in multiple-input multiple-output (MIMO) wireless transmission by adjusting the relative locations of horn antennas (HAs) in a 100 GHz optical wireless integration system, which can deliver a 50 Gb/s polarization-division-multiplexing quadrature-phase-shift-keying signal over 80 km single-mode fiber-28 and a 2×2 MIMO wireless link. For the parallel 2×2 MIMO wireless link, each receiver HA can only get wireless power from the corresponding transmitter HA, while for the crossover ones, the receiver HA can get wireless power from two transmitter HAs. At the wireless receiver, polarization demultiplexing is realized by the constant modulus algorithm (CMA) in the digital-signal-processing part. Compared to the parallel case, wireless interference causes about 2 dB optical signal-to-noise ratio penalty at a bit-error ratio (BER) of 3.8×10(-3) for the crossover cases if similar CMA taps are employed. The increase in CMA tap length can reduce wireless interference and improve BER performance. Furthermore, more CMA taps should be adopted to overcome the severe wireless interference when two pairs of transmitter and receiver HAs have different wireless distances.

Converged wireline and wireless signal transport over optical fibre access links

DEFF Research Database (Denmark)

Tafur Monroy, Idelfonso; Prince, Kamau; Osadchiy, Alexey Vladimirovich

2009-01-01

This article reviews emerging trends in converged optical-wireless communication systems and outline the role that photonic technologies are playing in making the vision of a wireline-wireless converged signal transport network a reality.......This article reviews emerging trends in converged optical-wireless communication systems and outline the role that photonic technologies are playing in making the vision of a wireline-wireless converged signal transport network a reality....

A General Model for Performance Evaluation in DS-CDMA Systems with Variable Spreading Factors

Science.gov (United States)

Chiaraluce, Franco; Gambi, Ennio; Righi, Giorgia

This paper extends previous analytical approaches for the study of CDMA systems to the relevant case of multipath environments where users can operate at different bit rates. This scenario is of interest for the Wideband CDMA strategy employed in UMTS, and the model permits the performance comparison of classic and more innovative spreading signals. The method is based on the characteristic function approach, that allows to model accurately the various kinds of interferences. Some numerical examples are given with reference to the ITU-R M. 1225 Recommendations, but the analysis could be extended to different channel descriptions.

DS-CDMA system outer loop power control and improvement for multi-service

Institute of Scientific and Technical Information of China (English)

Guan Mingxiang; Guo Qing; Li Xing

2008-01-01

When a new user accesses the CDMA system, the load will change drastically, and therefore, the advanced outer loop power control (OLPC) technology has to be adopted to enrich the target signal interference ratio (SIR) and improve the system performance. The existing problems about DS-CDMA outer loop power control for multi-service are introduced and the power control theoretical model is analyzed. System simulation is adopted on how to obtain the theoretical performance and parameter optimization of the power control algorithm. The OLPC algorithm is improved and the performance comparisons between the old algorithm and the improved algorithm are given. The results show good performance of the improved OLPC algorithm and prove the validity of the improved method for multi-service.

A Review on Successive Interference Cancellation Scheme Based on Optical CDMA Network

Science.gov (United States)

Alsowaidi, N.; Eltaif, T.; Mokhtar, M. R.

2014-12-01

Due to various desirable features of optical code division multiple access (OCDMA), it is believed this technique once developed and commercially available will be an integral part of optical access networks. Optical CDMA system suffers from a problem called multiple access interference (MAI) which limits the number of active users, it occurs when number of active users share the same carriers. The aim of this paper is to review successive interference cancellation (SIC) scheme based on optical CDMA system. The paper also reviews the system performance in presence of shot noise, thermal noise, and phase-induced intensity noise (PIIN). A comprehensive review on the mathematical model of SIC scheme using direct detection (DS) and spectral amplitude coding (SAC) were presented in this article.

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.

20-meter underwater wireless optical communication link with 1.5 Gbps data rate.

Science.gov (United States)

Shen, Chao; Guo, Yujian; Oubei, Hassan M; Ng, Tien Khee; Liu, Guangyu; Park, Ki-Hong; Ho, Kang-Ting; Alouini, Mohamed-Slim; Ooi, Boon S

2016-10-31

The video streaming, data transmission, and remote control in underwater call for high speed (Gbps) communication link with a long channel length (~10 meters). We present a compact and low power consumption underwater wireless optical communication (UWOC) system utilizing a 450-nm laser diode (LD) and a Si avalanche photodetector. With the LD operating at a driving current of 80 mA with an optical power of 51.3 mW, we demonstrated a high-speed UWOC link offering a data rate up to 2 Gbps over a 12-meter-long, and 1.5 Gbps over a record 20-meter-long underwater channel. The measured bit-error rate (BER) are 2.8 × 10-5, and 3.0 × 10-3, respectively, which pass well the forward error correction (FEC) criterion.

Uniform Circular Antenna Array Applications in Coded DS-CDMA Mobile Communication Systems

National Research Council Canada - National Science Library

Seow, Tian

2003-01-01

...) has greatly increased. This thesis examines the use of an equally spaced circular adaptive antenna array at the mobile station for a typical coded direct sequence code division multiple access (DS-CDMA...

A CDMA Spotbeam Architecture for the Next Generation Satellite System (NGSS) for the Aeronautical Telecommunications Network (ATN)

Science.gov (United States)

Raghavan, Rajesh S.; Shamma, Mohammed A.

2003-01-01

This paper will present work being done to model and simulate a CDMA based Mobile Satellite System architecture for providing all or part of the future Air Traffic Management (ATM) services. Such a system, will help in relieving the dependence on ground based networks, if not eliminate it. Additionally such an architecture can be used in parallel or as a supplementary service along with ground based links to help alleviate any capacity bottlenecks, or in areas where such services are difficult to make available such as in oceanic, remote areas outside the jet highways, or in developing countries where ground services are less available.

Simulative Analysis of Inter-Satellite Optical Wireless Communication (IsOWC) Link with EDFA

Science.gov (United States)

Singh, Mehtab; Singh, Navpreet

2018-04-01

In this paper, simulative analysis and performance comparison of different EDFA (Erbium-doped fiber amplifier) configurations in a 10 Gbps inter-satellite optical wireless communication (IsOWC) link have been reported for a 5,000 km long link and 1,550 nm operating wavelength. The results show that system in which both pre-amplifier and booster amplifier stages are implemented simultaneously outperforms systems with only pre-amplifier and booster amplifier stage. From the results, it can be seen that by deploying a transmission power level of 15 dBm, a link distance of 9,600 km can be achieved with a quality factor of 6.01 dB and BER (Bit error rate) of 1.07×10-9. Also, in this paper, the performance of an 8×7 Gbps WDM-IsOWC link has been reported. The results show that by using both EDFA pre-amplifier and booster amplifier stages, a link distance of 8,000 km for each channel is achievable with desired performance levels (Q≥6 and BER≤10-9). Also, the effect of channel spacing on the performance of WDM-IsOWC link is investigated. The results show that the received signal has acceptable performance levels when the channel spacing is 100 GHz but when the channel spacing is reduced to 80 GHz, the quality of the received signal degrades and link distance decreases.

Comparison of equalisation strategies for multi-carrier CDMA

OpenAIRE

Cooper, MA; Armour, SMD; Bian, YQ; McGeehan, JP

2003-01-01

This paper focuses on the bit error rate (BER) performance of equalisation strategies for a downlink MC-CDMA based system. Simulation results utilising maximal ratio combining (MRC), orthogonal restoring combining (ORC), equal gain combining (EGC) and minimum mean square error combining (MMSEC) for a multiuser scenario are presented. In addition, we analyse the relative complexities of each scheme and discuss their suitability for implementation in future consumer products

Multiple Access Interference Reduction Using Received Response Code Sequence for DS-CDMA UWB System

Science.gov (United States)

Toh, Keat Beng; Tachikawa, Shin'ichi

This paper proposes a combination of novel Received Response (RR) sequence at the transmitter and a Matched Filter-RAKE (MF-RAKE) combining scheme receiver system for the Direct Sequence-Code Division Multiple Access Ultra Wideband (DS-CDMA UWB) multipath channel model. This paper also demonstrates the effectiveness of the RR sequence in Multiple Access Interference (MAI) reduction for the DS-CDMA UWB system. It suggests that by using conventional binary code sequence such as the M sequence or the Gold sequence, there is a possibility of generating extra MAI in the UWB system. Therefore, it is quite difficult to collect the energy efficiently although the RAKE reception method is applied at the receiver. The main purpose of the proposed system is to overcome the performance degradation for UWB transmission due to the occurrence of MAI during multiple accessing in the DS-CDMA UWB system. The proposed system improves the system performance by improving the RAKE reception performance using the RR sequence which can reduce the MAI effect significantly. Simulation results verify that significant improvement can be obtained by the proposed system in the UWB multipath channel models.

Coding Across Multicodes and Time in CDMA Systems Employing MMSE Multiuser Detector

Directory of Open Access Journals (Sweden)

Park Jeongsoon

2004-01-01

Full Text Available When combining a multicode CDMA system with convolutional coding, two methods have been considered in the literature. In one method, coding is across time in each multicode channel while in the other the coding is across both multicodes and time. In this paper, a performance/complexity analysis of decoding metrics and trellis structures for the two schemes is carried out. It is shown that the latter scheme can exploit the multicode diversity inherent in convolutionally coded direct sequence code division multiple access (DS-CDMA systems which employ minimum mean squared error (MMSE multiuser detectors. In particular, when the MMSE detector provides sufficiently different signal-to-interference ratios (SIRs for the multicode channels, coding across multicodes and time can obtain significant performance gain over coding across time, with nearly the same decoding complexity.

A study of the impact of frequency selectivity on link adaptive wireless LAN systems

OpenAIRE

Armour, SMD; Doufexi, A; Nix, AR; Bull, DR

2002-01-01

Wireless local area networks (WLANs) supporting broadband multimedia communication are being developed and standardized around the world. The HIPERLAN/2, 802.11a and HiSWANa standards provide channel adaptive data rates between 6 and 54 Mbps in the 5GHz radio band. The link adaptation mechanism is not specified in the standards. In this paper the performance of the HIPERLAN/2 system is evaluated in terms of throughput in a range of test channels with different degrees of frequency selectivity...

Performance Comparison of Orthogonal and Quasi-orthogonal Codes in Quasi-Synchronous Cellular CDMA Communication

Science.gov (United States)

Jos, Sujit; Kumar, Preetam; Chakrabarti, Saswat

Orthogonal and quasi-orthogonal codes are integral part of any DS-CDMA based cellular systems. Orthogonal codes are ideal for use in perfectly synchronous scenario like downlink cellular communication. Quasi-orthogonal codes are preferred over orthogonal codes in the uplink communication where perfect synchronization cannot be achieved. In this paper, we attempt to compare orthogonal and quasi-orthogonal codes in presence of timing synchronization error. This will give insight into the synchronization demands in DS-CDMA systems employing the two classes of sequences. The synchronization error considered is smaller than chip duration. Monte-Carlo simulations have been carried out to verify the analytical and numerical results.

Promoting Wired Links in Wireless Mesh Networks: An Efficient Engineering Solution

Science.gov (United States)

Barekatain, Behrang; Raahemifar, Kaamran; Ariza Quintana, Alfonso; Triviño Cabrera, Alicia

2015-01-01

Wireless Mesh Networks (WMNs) cannot completely guarantee good performance of traffic sources such as video streaming. To improve the network performance, this study proposes an efficient engineering solution named Wireless-to-Ethernet-Mesh-Portal-Passageway (WEMPP) that allows effective use of wired communication in WMNs. WEMPP permits transmitting data through wired and stable paths even when the destination is in the same network as the source (Intra-traffic). Tested with four popular routing protocols (Optimized Link State Routing or OLSR as a proactive protocol, Dynamic MANET On-demand or DYMO as a reactive protocol, DYMO with spanning tree ability and HWMP), WEMPP considerably decreases the end-to-end delay, jitter, contentions and interferences on nodes, even when the network size or density varies. WEMPP is also cost-effective and increases the network throughput. Moreover, in contrast to solutions proposed by previous studies, WEMPP is easily implemented by modifying the firmware of the actual Ethernet hardware without altering the routing protocols and/or the functionality of the IP/MAC/Upper layers. In fact, there is no need for modifying the functionalities of other mesh components in order to work with WEMPPs. The results of this study show that WEMPP significantly increases the performance of all routing protocols, thus leading to better video quality on nodes. PMID:25793516

Security For Wireless Sensor Network

OpenAIRE

Saurabh Singh,; Dr. Harsh Kumar Verma

2011-01-01

Wireless sensor network is highly vulnerable to attacks because it consists of various resourceconstrained devices with their low battery power, less memory, and associated low energy. Sensor nodescommunicate among themselves via wireless links. However, there are still a lot of unresolved issues in wireless sensor networks of which security is one of the hottest research issues. Sensor networks aredeployed in hostile environments. Environmental conditions along with resource-constraints give...

On the High Altitude Platform (HAP W-CDMA System Capacity

Directory of Open Access Journals (Sweden)

L. de Haro-Ariet

2004-06-01

Full Text Available The performance of a downlink power control model, based on a n-thpower distance law, is evaluated for high altitude platform station(HAPS W-CDMA systems. The downlink capacity using this model iscompared with the uplink capacity. It is shown that the uplink capacityis higher than the downlink capacity.

Asymptotic Performance Analysis of the k-th Best Link Selection over Wireless Fading Channels: An Extreme Value Theory Approach

KAUST Repository

Al-Badarneh, Yazan Hussein

2018-01-25

We consider a general selection-diversity (SD) scheme in which the k-th best link is selected from a number of links. We use extreme value theory (EVT) to derive simple closed-form asymptotic expressions for the average throughput, effective throughput and average bit error probability (BEP) for the k-th best link over various channel models that are widely used to characterize fading in wireless communication systems. As an application example, we consider the Weibull fading channel model and verify the accuracy of the derived asymptotic expressions through Monte Carlo simulations.

Asymptotic Performance Analysis of the k-th Best Link Selection over Wireless Fading Channels: An Extreme Value Theory Approach

KAUST Repository

Al-Badarneh, Yazan Hussein; Georghiades, Costas; Alouini, Mohamed-Slim

2018-01-01

We consider a general selection-diversity (SD) scheme in which the k-th best link is selected from a number of links. We use extreme value theory (EVT) to derive simple closed-form asymptotic expressions for the average throughput, effective throughput and average bit error probability (BEP) for the k-th best link over various channel models that are widely used to characterize fading in wireless communication systems. As an application example, we consider the Weibull fading channel model and verify the accuracy of the derived asymptotic expressions through Monte Carlo simulations.

Robust MOE Detector for DS-CDMA Systems with Signature Waveform Mismatch

Science.gov (United States)

Lin, Tsui-Tsai

In this letter, a decision-directed MOE detector with excellent robustness against signature waveform mismatch is proposed for DS-CDMA systems. Both the theoretic analysis and computer simulation results demonstrate that the proposed detector can provide better SINR performance than that of conventional detectors.

Adaptive Multiuser Detectors for DS-CDMA Systems

Directory of Open Access Journals (Sweden)

Paul Jean Etienne Jeszensky

2006-02-01

Full Text Available This work makes a review of the main Adaptives Multi-user Detectors (MuD-Adpt for Direct Sequence - Code Division Multiple Access (DS-CDMA systems. The MuD-Adpt based on Minimum Mean Square Error (MMSE and Decorrelator (MuD-Dec are focused. Multi-user detectors show great resistance to the near-far effect and combat effectively the Multiple Access Interference (MAI. Comparative numeric results characterize the substantial performance improvement of those detectors in relation to the matched filter conventional receiver (Conv.

A Rapid Prototyping Environment for Wireless Communication Embedded Systems

Directory of Open Access Journals (Sweden)

Bryan A. Jones

2003-05-01

Full Text Available This paper introduces a rapid prototyping methodology which overcomes important barriers in the design and implementation of digital signal processing (DSP algorithms and systems on embedded hardware platforms, such as cellular phones. This paper describes rapid prototyping in terms of a simulation/prototype bridge and in terms of appropriate language design. The simulation/prototype bridge combines the strengths of simulation and of prototyping, allowing the designer to develop and evaluate next-generation communications systems, partly in simulation on a host computer and partly as a prototype on embedded hardware. Appropriate language design allows designers to express a communications system as a block diagram, in which each block represents an algorithm specified by a set of equations. Software tools developed for this paper implement both concepts, and have been successfully used in the development of a next-generation code division multiple access (CDMA cellular wireless communications system.

Delay Estimation in Long-Code Asynchronous DS/CDMA Systems Using Multiple Antennas

Directory of Open Access Journals (Sweden)

Sirbu Marius

2004-01-01

Full Text Available The problem of propagation delay estimation in asynchronous long-code DS-CDMA multiuser systems is addressed. Almost all the methods proposed so far in the literature for propagation delay estimation are derived for short codes and the knowledge of the codes is exploited by the estimators. In long-code CDMA, the spreading code is aperiodic and the methods developed for short codes may not be used or may increase the complexity significantly. For example, in the subspace-based estimators, the aperiodic nature of the code may require subspace tracking. In this paper we propose a novel method for simultaneous estimation of the propagation delays of several active users. A specific multiple-input multiple-output (MIMO system model is constructed in a multiuser scenario. In such model the channel matrix contains information about both the users propagation delays and channel impulse responses. Consequently, estimates of the delays are obtained as a by-product of the channel estimation task. The channel matrix has a special structure that is exploited in estimating the delays. The proposed delay estimation method lends itself to an adaptive implementation. Thus, it may be applied to joint channel and delay estimation in uplink DS-CDMA analogously to the method presented by the authors in 2003. The performance of the proposed method is studied in simulation using realistic time-varying channel model and different SNR levels in the face of near-far effects, and using low spreading factor (high data rates.

Adaptive Modulation and Coding for LTE Wireless Communication

Science.gov (United States)

Hadi, S. S.; Tiong, T. C.

2015-04-01

Long Term Evolution (LTE) is the new upgrade path for carrier with both GSM/UMTS networks and CDMA2000 networks. The LTE is targeting to become the first global mobile phone standard regardless of the different LTE frequencies and bands use in other countries barrier. Adaptive Modulation and Coding (AMC) is used to increase the network capacity or downlink data rates. Various modulation types are discussed such as Quadrature Phase Shift Keying (QPSK), Quadrature Amplitude Modulation (QAM). Spatial multiplexing techniques for 4×4 MIMO antenna configuration is studied. With channel station information feedback from the mobile receiver to the base station transmitter, adaptive modulation and coding can be applied to adapt to the mobile wireless channels condition to increase spectral efficiencies without increasing bit error rate in noisy channels. In High-Speed Downlink Packet Access (HSDPA) in Universal Mobile Telecommunications System (UMTS), AMC can be used to choose modulation types and forward error correction (FEC) coding rate.

Connectivity model for Inter-working multi-hop wireless networks

CSIR Research Space (South Africa)

Salami, O

2009-08-01

Full Text Available pairs in inter-working multi-hop wireless networks can be evaluated based on the availability of radio links and communication routes. This paper presents an analytical study of the link and route availability in inter-working multi-hop wireless networks....

Performance of DS-CDMA systems with optimal hard-decision parallel interference cancellation

NARCIS (Netherlands)

Hofstad, van der R.W.; Klok, M.J.

2003-01-01

We study a multiuser detection system for code-division multiple access (CDMA). We show that applying multistage hard-decision parallel interference cancellation (HD-PIC) significantly improves performance compared to the matched filter system. In (multistage) HD-PIC, estimates of the interfering

FIR Filter of DS-CDMA UWB Modem Transmitter

Science.gov (United States)

Kang, Kyu-Min; Cho, Sang-In; Won, Hui-Chul; Choi, Sang-Sung

This letter presents low-complexity digital pulse shaping filter structures of a direct sequence code division multiple access (DS-CDMA) ultra wide-band (UWB) modem transmitter with a ternary spreading code. The proposed finite impulse response (FIR) filter structures using a look-up table (LUT) have the effect of saving the amount of memory by about 50% to 80% in comparison to the conventional FIR filter structures, and consequently are suitable for a high-speed parallel data process.

Wireless sensor communications and internet connectivity for sensor networks

Energy Technology Data Exchange (ETDEWEB)

Dunbar, M. [Crossbow Technology, Inc., San Jose, CA (United States)

2001-07-01

A wireless sensor network architecture is an integrated hardware/software solution that has the potential to change the way sensors are used in a virtually unlimited range of industries and applications. By leveraging Bluetooth wireless technology for low-cost, short-range radio links, wireless sensor networks such as CrossNet{sup TM} enable users to create wireless sensor networks. These wireless networks can link dozens or hundreds of sensors of disparate types and brands with data acquisition/analysis systems, such as handheld devices, internet-enabled laptop or desktop PCs. The overwhelming majority of sensor applications are hard-wired at present, and since wiring is often the most time-consuming, tedious, trouble-prone and expensive aspect of sensor applications, users in many fields will find compelling reasons to adopt the wireless sensor network solution. (orig.)

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

Conjugate Image Theory Applied on Capacitive Wireless Power Transfer

Directory of Open Access Journals (Sweden)

Ben Minnaert

2017-01-01

Full Text Available Wireless power transfer using a magnetic field through inductive coupling is steadily entering the market in a broad range of applications. However, for certain applications, capacitive wireless power transfer using electric coupling might be preferable. In order to obtain a maximum power transfer efficiency, an optimal compensation network must be designed at the input and output ports of the capacitive wireless link. In this work, the conjugate image theory is applied to determine this optimal network as a function of the characteristics of the capacitive wireless link, as well for the series as for the parallel topology. The results are compared with the inductive power transfer system. Introduction of a new concept, the coupling function, enables the description of the compensation network of both an inductive and a capacitive system in two elegant equations, valid for the series and the parallel topology. This approach allows better understanding of the fundamentals of the wireless power transfer link, necessary for the design of an efficient system.

Handover aspects for a Low Earth Orbit (LEO) CDMA Land Mobile Satellite (LMS) system

Science.gov (United States)

Carter, P.; Beach, M. A.

1993-01-01

This paper addresses the problem of handoff in a land mobile satellite (LMS) system between adjacent satellites in a low earth orbit (LEO) constellation. In particular, emphasis is placed on the application of soft handoff in a direct sequence code division multiple access (DS-CDMA) LMS system. Soft handoff is explained in terms of terrestrial macroscopic diversity, in which signals transmitted via several independent fading paths are combined to enhance the link quality. This concept is then reconsidered in the context of a LEO LMS system. A two-state Markov channel model is used to simulate the effects of shadowing on the communications path from the mobile to each satellite during handoff. The results of the channel simulation form a platform for discussion regarding soft handoff, highlighting the potential merits of the scheme when applied in a LEO LMS environment.

Design and Optimization of a 3-Coil Inductive Link for Efficient Wireless Power Transmission.

Science.gov (United States)

Kiani, Mehdi; Jow, Uei-Ming; Ghovanloo, Maysam

2011-07-14

Inductive power transmission is widely used to energize implantable microelectronic devices (IMDs), recharge batteries, and energy harvesters. Power transfer efficiency (PTE) and power delivered to the load (PDL) are two key parameters in wireless links, which affect the energy source specifications, heat dissipation, power transmission range, and interference with other devices. To improve the PTE, a 4-coil inductive link has been recently proposed. Through a comprehensive circuit based analysis that can guide a design and optimization scheme, we have shown that despite achieving high PTE at larger coil separations, the 4-coil inductive links fail to achieve a high PDL. Instead, we have proposed a 3-coil inductive power transfer link with comparable PTE over its 4-coil counterpart at large coupling distances, which can also achieve high PDL. We have also devised an iterative design methodology that provides the optimal coil geometries in a 3-coil inductive power transfer link. Design examples of 2-, 3-, and 4-coil inductive links have been presented, and optimized for 13.56 MHz carrier frequency and 12 cm coupling distance, showing PTEs of 15%, 37%, and 35%, respectively. At this distance, the PDL of the proposed 3-coil inductive link is 1.5 and 59 times higher than its equivalent 2- and 4-coil links, respectively. For short coupling distances, however, 2-coil links remain the optimal choice when a high PDL is required, while 4-coil links are preferred when the driver has large output resistance or small power is needed. These results have been verified through simulations and measurements.

2-Step Maximum Likelihood Channel Estimation for Multicode DS-CDMA with Frequency-Domain Equalization

Science.gov (United States)

Kojima, Yohei; Takeda, Kazuaki; Adachi, Fumiyuki

Frequency-domain equalization (FDE) based on the minimum mean square error (MMSE) criterion can provide better downlink bit error rate (BER) performance of direct sequence code division multiple access (DS-CDMA) than the conventional rake combining in a frequency-selective fading channel. FDE requires accurate channel estimation. In this paper, we propose a new 2-step maximum likelihood channel estimation (MLCE) for DS-CDMA with FDE in a very slow frequency-selective fading environment. The 1st step uses the conventional pilot-assisted MMSE-CE and the 2nd step carries out the MLCE using decision feedback from the 1st step. The BER performance improvement achieved by 2-step MLCE over pilot assisted MMSE-CE is confirmed by computer simulation.

Impact of Radio Link Unreliability on the Connectivity of Wireless Sensor Networks

Directory of Open Access Journals (Sweden)

Gorce Jean-Marie

2007-01-01

Full Text Available Many works have been devoted to connectivity of ad hoc networks. This is an important feature for wireless sensor networks (WSNs to provide the nodes with the capability of communicating with one or several sinks. In most of these works, radio links are assumed ideal, that is, with no transmission errors. To fulfil this assumption, the reception threshold should be high enough to guarantee that radio links have a low transmission error probability. As a consequence, all unreliable links are dismissed. This approach is suboptimal concerning energy consumption because unreliable links should permit to reduce either the transmission power or the number of active nodes. The aim of this paper is to quantify the contribution of unreliable long hops to an increase of the connectivity of WSNs. In our model, each node is assumed to be connected to each other node in a probabilistic manner. Such a network is modeled as a complete random graph, that is, all edges exist. The instantaneous node degree is then defined as the number of simultaneous valid single-hop receptions of the same message, and finally the mean node degree is computed analytically in both AWGN and block-fading channels. We show the impact on connectivity of two MACs and routing parameters. The first one is the energy detection level such as the one used in carrier sense mechanisms. The second one is the reliability threshold used by the routing layer to select stable links only. Both analytic and simulation results show that using opportunistic protocols is challenging.

Impact of Radio Link Unreliability on the Connectivity of Wireless Sensor Networks

Directory of Open Access Journals (Sweden)

Jean-Marie Gorce

2007-06-01

Full Text Available Many works have been devoted to connectivity of ad hoc networks. This is an important feature for wireless sensor networks (WSNs to provide the nodes with the capability of communicating with one or several sinks. In most of these works, radio links are assumed ideal, that is, with no transmission errors. To fulfil this assumption, the reception threshold should be high enough to guarantee that radio links have a low transmission error probability. As a consequence, all unreliable links are dismissed. This approach is suboptimal concerning energy consumption because unreliable links should permit to reduce either the transmission power or the number of active nodes. The aim of this paper is to quantify the contribution of unreliable long hops to an increase of the connectivity of WSNs. In our model, each node is assumed to be connected to each other node in a probabilistic manner. Such a network is modeled as a complete random graph, that is, all edges exist. The instantaneous node degree is then defined as the number of simultaneous valid single-hop receptions of the same message, and finally the mean node degree is computed analytically in both AWGN and block-fading channels. We show the impact on connectivity of two MACs and routing parameters. The first one is the energy detection level such as the one used in carrier sense mechanisms. The second one is the reliability threshold used by the routing layer to select stable links only. Both analytic and simulation results show that using opportunistic protocols is challenging.

Performance Analysis of a New Coded TH-CDMA Scheme in Dispersive Infrared Channel with Additive Gaussian Noise

Science.gov (United States)

Hamdi, Mazda; Kenari, Masoumeh Nasiri

2013-06-01

We consider a time-hopping based multiple access scheme introduced in [1] for communication over dispersive infrared links, and evaluate its performance for correlator and matched filter receivers. In the investigated time-hopping code division multiple access (TH-CDMA) method, the transmitter benefits a low rate convolutional encoder. In this method, the bit interval is divided into Nc chips and the output of the encoder along with a PN sequence assigned to the user determines the position of the chip in which the optical pulse is transmitted. We evaluate the multiple access performance of the system for correlation receiver considering background noise which is modeled as White Gaussian noise due to its large intensity. For the correlation receiver, the results show that for a fixed processing gain, at high transmit power, where the multiple access interference has the dominant effect, the performance improves by the coding gain. But at low transmit power, in which the increase of coding gain leads to the decrease of the chip time, and consequently, to more corruption due to the channel dispersion, there exists an optimum value for the coding gain. However, for the matched filter, the performance always improves by the coding gain. The results show that the matched filter receiver outperforms the correlation receiver in the considered cases. Our results show that, for the same bandwidth and bit rate, the proposed system excels other multiple access techniques, like conventional CDMA and time hopping scheme.

Data transmission techniques for short-range optical fiber and wireless communication links

DEFF Research Database (Denmark)

Pham, Tien Thang

The research work described in this thesis is devoted to experimental investigation of techniques for cost-effective high-speed optical communications supporting both wired and wireless services. The main contributions of this thesis have expanded the state-of-the-art in two main areas: high......-speed optical/wireless integration and advanced modulation formats for intensity modulation with direct detection (IM/DD) optical systems. Regarding optical/wireless integration, this thesis focuses on integration of broadband ultra-wide band (UWB) and 60-GHz band wireless systems into optical fiber access...... networks to distribute wireless services in personal area networks (PANs). Photonic technologies to generate and distribute gigabit UWB and 60-GHz-band signals are proposed and demonstrated. Two novel methods are proposed and demonstrated to optically generate Federal Communications Commission (FCC...

Assistance System for Disabled People: A Robot Controlled by Blinking and Wireless Link

Science.gov (United States)

Del Val, Lara; Jiménez, María I.; Alonso, Alonso; de La Rosa, Ramón; Izquierdo, Alberto; Carrera, Albano

Disabled people already profit from a lot of technical assistance that improves their quality of life. This article presents a system which will allow interaction between a physically disabled person and his environment. This system is controlled by voluntary muscular movements, particularly those of face muscles. These movements will be translated into machine-understandable instructions, and they will be sent by means of a wireless link to a mobile robot that will execute them. Robot includes a video camera, in order to show the user the environment of the route that the robot follows. This system gives a greater personal autonomy to people with reduced mobility.

Low Complexity Iterative Joint Channel Estimation and Multiuser Detection for DS-CDMA

DEFF Research Database (Denmark)

Christensen, Søren Skovgård; Kocian, Alexander; Fleury, Bernard Henri

2004-01-01

Previously the SAGE algorithm was applied to sub-optimal yet efficient Joint data Detection and channel Estimation (JDE) for DS-CDMA of moderate time complexity. Modifying the expectation and maximization steps of the SAGE-JDE scheme, it is possible to obtain an efficient receiver architecture...

Proposal of Wireless Traffic Control Schemes for Wireless LANs

Science.gov (United States)

Hiraguri, Takefumi; Ichikawa, Takeo; Iizuka, Masataka; Kubota, Shuji

This paper proposes two traffic control schemes to support the communication quality of multimedia streaming services such as VoIP and audio/video over IEEE 802.11 wireless LAN systems. The main features of the proposed scheme are bandwidth control for each flow of the multimedia streaming service and load balancing between access points (APs) of the wireless LAN by using information of data link, network and transport layers. The proposed schemes are implemented on a Linux machine which is called the wireless traffic controller (WTC). The WTC connects a high capacity backbone network and an access network to which the APs are attached. We evaluated the performance of the proposed WTC and confirmed that the communication quality of the multimedia streaming would be greatly improved by using this technique.

RLS Channel Estimation with Adaptive Forgetting Factor for DS-CDMA Frequency-Domain Equalization

Science.gov (United States)

Kojima, Yohei; Tomeba, Hiromichi; Takeda, Kazuaki; Adachi, Fumiyuki

Frequency-domain equalization (FDE) based on the minimum mean square error (MMSE) criterion can increase the downlink bit error rate (BER) performance of DS-CDMA beyond that possible with conventional rake combining in a frequency-selective fading channel. FDE requires accurate channel estimation. Recently, we proposed a pilot-assisted channel estimation (CE) based on the MMSE criterion. Using MMSE-CE, the channel estimation accuracy is almost insensitive to the pilot chip sequence, and a good BER performance is achieved. In this paper, we propose a channel estimation scheme using one-tap recursive least square (RLS) algorithm, where the forgetting factor is adapted to the changing channel condition by the least mean square (LMS)algorithm, for DS-CDMA with FDE. We evaluate the BER performance using RLS-CE with adaptive forgetting factor in a frequency-selective fast Rayleigh fading channel by computer simulation.

Beyond 100 Gbit/s wireless connectivity enabled by THz photonics

DEFF Research Database (Denmark)

Yu, Xianbin; Jia, Shi; Pang, Xiaodan

2017-01-01

Beyond 100Gbit/s wireless connectivity is appreciated in many scenarios, such as big data wireless cloud, ultrafast wireless download, large volume data transfer, etc. In this paper, we will present our recent achievements on beyond 100Gbit/s ultrafast terahertz (THz) wireless links enabled by TH...... photonics....

Experimental Characterization of LTE Wireless Links in High-Speed Trains

Directory of Open Access Journals (Sweden)

Tomás Domínguez-Bolaño

2017-01-01

Full Text Available Multimedia and data-based services experienced a nonstopping growth over the last few years. People are continuously on the move using devices to access multimedia contents or other data-based services. Due to this, railway companies are showing a great interest in deploying broadband mobile wireless networks in high-speed-trains with the aim of supporting both passenger services provisioning as well as automatic train control and signaling. Nowadays, the most widely used technology for communications between trains and the railway infrastructure is GSM for Railways (GSM-R; however, it has limited capabilities to support such advanced services. Due to its success in the mass market, Long Term Evolution (LTE seems to be the best candidate to substitute GSM-R. In this paper, we experimentally characterize the downlink between an LTE Evolved NodeB (eNodeB and a high-speed train in a commercial high-speed line. We consider two links: the one between the eNodeB and the antennas placed outdoors on the train roof, and the direct link between the eNodeB and a receiver inside the train. Such a characterization consists in assessing the path loss, the Signal to Noise Ratio, the K-Factor, the Power Delay Profile, the delay spread, and the Doppler Power Spectral Density.

High performance mixed optical CDMA system using ZCC code and multiband OFDM

Directory of Open Access Journals (Sweden)

Nawawi N. M.

2017-01-01

Full Text Available In this paper, we have proposed a high performance network design, which is based on mixed optical Code Division Multiple Access (CDMA system using Zero Cross Correlation (ZCC code and multiband Orthogonal Frequency Division Multiplexing (OFDM called catenated OFDM. In addition, we also investigate the related changing parameters such as; effective power, number of user, number of band, code length and code weight. Then we theoretically analyzed the system performance comprehensively while considering up to five OFDM bands. The feasibility of the proposed system architecture is verified via the numerical analysis. The research results demonstrated that our developed modulation solution can significantly enhanced the total number of user; improving up to 80% for five catenated bands compared to traditional optical CDMA system, with the code length equals to 80, transmitted at 622 Mbps. It is also demonstrated that the BER performance strongly depends on number of weight, especially with less number of users. As the number of weight increases, the BER performance is better.

High performance mixed optical CDMA system using ZCC code and multiband OFDM

Science.gov (United States)

Nawawi, N. M.; Anuar, M. S.; Junita, M. N.; Rashidi, C. B. M.

2017-11-01

In this paper, we have proposed a high performance network design, which is based on mixed optical Code Division Multiple Access (CDMA) system using Zero Cross Correlation (ZCC) code and multiband Orthogonal Frequency Division Multiplexing (OFDM) called catenated OFDM. In addition, we also investigate the related changing parameters such as; effective power, number of user, number of band, code length and code weight. Then we theoretically analyzed the system performance comprehensively while considering up to five OFDM bands. The feasibility of the proposed system architecture is verified via the numerical analysis. The research results demonstrated that our developed modulation solution can significantly enhanced the total number of user; improving up to 80% for five catenated bands compared to traditional optical CDMA system, with the code length equals to 80, transmitted at 622 Mbps. It is also demonstrated that the BER performance strongly depends on number of weight, especially with less number of users. As the number of weight increases, the BER performance is better.

Multirate IP traffic transmission in flexible access networks based on optical FFH-CDMA

DEFF Research Database (Denmark)

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

2016-01-01

In this paper, we propose a new IP transmission architecture over optical fast frequency hopping code-division multiple-access (OFFH-CDMA) network capable of supporting multirate transmissions for applications in flexible optical access networks. The proposed network architecture is independent...

Partial Interference and Its Performance Impact on Wireless Multiple Access Networks

Directory of Open Access Journals (Sweden)

Lau WingCheong

2010-01-01

Full Text Available To determine the capacity of wireless multiple access networks, the interference among the wireless links must be accurately modeled. In this paper, we formalize the notion of the partial interference phenomenon observed in many recent wireless measurement studies and establish analytical models with tractable solutions for various types of wireless multiple access networks. In particular, we characterize the stability region of IEEE 802.11 networks under partial interference with two potentially unsaturated links numerically. We also provide a closed-form solution for the stability region of slotted ALOHA networks under partial interference with two potentially unsaturated links and obtain a partial characterization of the boundary of the stability region for the general M-link case. Finally, we derive a closed-form approximated solution for the stability region for general M-link slotted ALOHA system under partial interference effects. Based on our results, we demonstrate that it is important to model the partial interference effects while analyzing wireless multiple access networks. This is because such considerations can result in not only significant quantitative differences in the predicted system capacity but also fundamental qualitative changes in the shape of the stability region of the systems.

An FPGA-based DS-CDMA multiuser demodulator employing adaptive multistage parallel interference cancellation

Science.gov (United States)

Li, Xinhua; Song, Zhenyu; Zhan, Yongjie; Wu, Qiongzhi

2009-12-01

Since the system capacity is severely limited, reducing the multiple access interfere (MAI) is necessary in the multiuser direct-sequence code division multiple access (DS-CDMA) system which is used in the telecommunication terminals data-transferred link system. In this paper, we adopt an adaptive multistage parallel interference cancellation structure in the demodulator based on the least mean square (LMS) algorithm to eliminate the MAI on the basis of overviewing various of multiuser dectection schemes. Neither a training sequence nor a pilot signal is needed in the proposed scheme, and its implementation complexity can be greatly reduced by a LMS approximate algorithm. The algorithm and its FPGA implementation is then derived. Simulation results of the proposed adaptive PIC can outperform some of the existing interference cancellation methods in AWGN channels. The hardware setup of mutiuser demodulator is described, and the experimental results based on it demonstrate that the simulation results shows large performance gains over the conventional single-user demodulator.

Challenging Aspects of Terahertz Terabit Wireless Communications

DEFF Research Database (Denmark)

Yu, Xianbin; Galili, Michael; Jepsen, Peter Uhd

The increasing demand on fast wireless communications, e.g. huge data file transferring and mobile broadband access, has driven wireless communication systems into a path towards Terabit era. Terahertz (THz) technology is promising due to its unique features, such as unlimited bandwidth available......, in terms of THz generation and link power budget. The THz atmospheric absorption is another critical issue to limit wireless communication range....

ANALISIS PERILAKU KONSUMEN DALAM MEMILIH JASA LAYANAN OPERATOR MOBILE PHONE YANG BERBASIS CDMA DAN GSM

Directory of Open Access Journals (Sweden)

Demitri Marvin Kadhaffi

2012-05-01

Full Text Available ABSTRAKS Tujuan penelitian ini adalah (1 menganalisis faktor-faktor yang dipertimbangkan konsumen dalam memilih suatu jasa layanan operator mobile phone (baik CDMA maupun GSM, (2 menganalsis variabel dominan yang mempengaruhi perilaku konsumen dalam memilih jasa layanan operator Jenis penelitian ini adalah applied research dengan metode penelitian studi kausal. Penelitian ini ditujukan pada segmen pelajar dan mahasiswa di Kota Malang yang termasuk kelompok Net Generations (yang lahir antara tahun 1977-1997 dengan batas minimal umur untuk responden adalah 17 tahun.  Kerangka Sampel untuk penelitian ini adalah pengguna kartu CDMA dan GSM sebanyak 175 responden. Tehnik Sampling yang digunakan adalah desain sampel non probability dengan metode purposive sample yang kedua yaitu quota sampling. Metode analisa data yang digunakan adalah analisa faktor dan analisa diskriminan Hasil analisa faktor terhadap 34 variabel diperoleh  7 faktor baru, yang diberi label sebagai berikut : (1 faktor citra produk (2 faktor pelayanan, (3 faktor pengaruh lingkungan, (4 faktor promosi,(5 faktor individual, (6 faktor harga, dan (7 faktor proses. Dari analisa diskriminan diperoleh hasil yang bertentangan dengan hipotesis yaitu ternyata variabel harga bukan merupakan variabel yang dominan dalam membedakan perilaku pelanggan operator CDMA dengan GSM. Mereka lebih sensitif terhadap proses produk. Hal ini mengarahkan pelanggan untuk kalangan pelajar dan mahasiswa sebagai kelompok smart. Hasil penelitian menyimpulkan bahwa untuk membangun keunggulan bersaing operator harus meraih keunggulan posisional melalui diferensiasi “content” jasa yang dihasilkan yaitu berupa proses, sebagai hasil dari aplikasi  positioning produk.   Kata kunci: perilaku konsumen, jasa layanan, mobile phone   ABSTRACT Objective of this research are (1 to identify factors that customer consider in choosing mobile phone operator service (whether CDMA and GSM, (2 to identify dominant variable that

Microwave materials for wireless applications

CERN Document Server

Cruickshank, David B

2011-01-01

This practical resource offers you an in-depth, up-to-date understanding of the use of microwave magnetic materials for cutting-edge wireless applications. The book discusses device applications used in wireless infrastructure base stations, point-to-point radio links, and a range of more specialized microwave systems. You find detailed discussions on the attributes of each family of magnetic materials with respect to specific wireless applications. Moreover, the book addresses two of the hottest topics in the field today - insertion loss and intermodulation. This comprehensive reference also

Intersystem Interference Reduction for Overlaid HAPS-Terrestrial CDMA System

Science.gov (United States)

Huang, Jeng-Ji; Wang, Wei-Ting; Li, Mingfu; Shiung, David; Ferng, Huei-Wen

In this letter, we propose that directional antennas, combined with power management, be incorporated to reduce intersystem interference in a shared band overlaid high altitude platform station (HAPS)-terrestrial code division multiple access (CDMA) system. To eliminate the HAPS to terrestrial interference, the HAPS is accessed only via directional antennas under the proposed scheme. By doing so, the uplink power to the HAPS can accordingly be increased, so that the terrestrial to HAPS interference is also effectively suppressed.

Cross-Layer Resource Allocation for Variable Bit Rate Multiclass Services in a Multirate Multicarrier DS-CDMA Network

Directory of Open Access Journals (Sweden)

Kee-Chaing Chua

2005-02-01

Full Text Available An approximate analytical formulation of the resource allocation problem for handling variable bit rate multiclass services in a cellular round-robin carrier-hopping multirate multicarrier direct-sequence code-division multiple-access (MC-DS-CDMA system is presented. In this paper, all grade-of-service (GoS or quality-of-service (QoS requirements at the connection level, packet level, and link layer are satisfied simultaneously in the system, instead of being satisfied at the connection level or at the link layer only. The analytical formulation shows how the GoS/QoS in the different layers are intertwined across the layers. A novelty of this paper is that the outages in the subcarriers are minimized by spreading the subcarriers' signal-to-interference ratio evenly among all the subcarriers by using a dynamic round-robin carrier-hopping allocation scheme. A complete sharing (CS scheme with guard capacity is used for the resource sharing policy at the connection level based on the mean rates of the connections. Numerical results illustrate that significant gain in the system utilization is achieved through the joint coupling of connection/packet levels and link layer.

A novel wireless local positioning system for airport (indoor) security

Science.gov (United States)

Zekavat, Seyed A.; Tong, Hui; Tan, Jindong

2004-09-01

A novel wireless local positioning system (WLPS) for airport (or indoor) security is introduced. This system is used by airport (indoor) security guards to locate all of, or a group of airport employees or passengers within the airport area. WLPS consists of two main parts: (1) a base station that is carried by security personnel; hence, introducing dynamic base station (DBS), and (2) a transponder (TRX) that is mounted on all people (including security personnel) present at the airport; thus, introducing them as active targets. In this paper, we (a) draw a futuristic view of the airport security systems, and the flow of information at the airports, (b) investigate the techniques of extending WLPS coverage area beyond the line-of-sight (LoS), and (c) study the performance of this system via standard transceivers, and direct sequence code division multiple access (DS-CDMA) systems with and without antenna arrays and conventional beamforming (BF).

Effects of simultaneous combined exposure to CDMA and WCDMA electromagnetic fields on serum hormone levels in rats

International Nuclear Information System (INIS)

Jin, Yeung Bae; Choi, Hyung-Do; Kim, Byung Chan; Pack, Jeong-Ki; Kim, Nam; Lee, Yun-Sil

2013-01-01

Despite more than a decade of research on the endocrine system, there have been no published studies about the effects of concurrent exposure of radiofrequency electromagnetic fields (RF-EMF) on this system. The present study investigated the several parameters of the endocrine system including melatonin, thyroid stimulating hormone, stress hormone and sex hormone after code division multiple access (CDMA, 849 MHz) and wideband code division multiple access (WCDMA, 1.95 GHz) signals for simultaneous exposure in rats. Sprague-Dawley rats were exposed to RF-EMF signals for 45 min/day, 5 days/week for up to 8 weeks. The whole-body average specific absorption rate (SAR) of CDMA or WCDMA was 2.0 W/kg (total 4.0 W/kg). At 4 and 8 weeks after the experiment began, each experimental group's 40 rats (male 20, female 20) were autopsied. Exposure for 8 weeks to simultaneous CDMA and WCDMA RF did not affect serum levels in rats of melatonin, thyroid stimulating hormone (TSH), triiodothyronine (T3) and thyroxin (T4), adrenocorticotropic hormone (ACTH) and sex hormones (testosterone and estrogen) as assessed by the ELISA method

Maximal Ratio Combining Using Channel Estimation in Chaos Based Pilot-Added DS-CDMA System with Antenna Diversity

Directory of Open Access Journals (Sweden)

Meher Krishna Patel

2017-01-01

Full Text Available This paper presents an adaptive multiuser transceiver scheme for DS-CDMA systems in which pilot symbols are added to users’ data to estimate complex channel fading coefficients. The performance of receiver antenna diversity with maximal ratio combining (MRC technique is analyzed for imperfect channel estimation in flat fading environments. The complex fading coefficients are estimated using least mean square (LMS algorithm and these coefficients are utilized by the maximal ratio combiner for generating the decision variable. Probability of error in closed form is derived. Further, the effect of pilot signal power on bit error rate (BER and BER performance of multiplexed pilot and data signal transmission scenario are investigated. We have compared the performance of added and multiplexed pilot-data systems and concluded the advantages of both systems. The proposed CDMA technique uses the chaotic sequence as spreading sequence. Assuming proper synchronization, the computer simulation results demonstrate the better bit error rate performance in the presence of channel estimator in the chaotic based CDMA system and the receiver antenna diversity technique further improves the performance of the proposed system. Also, no channel estimator is required if there is no phase distortion to the transmitted signal.

An accurate evaluation of the performance of asynchronous DS-CDMA systems with zero-correlation-zone coding in Rayleigh fading

Science.gov (United States)

Walker, Ernest; Chen, Xinjia; Cooper, Reginald L.

2010-04-01

An arbitrarily accurate approach is used to determine the bit-error rate (BER) performance for generalized asynchronous DS-CDMA systems, in Gaussian noise with Raleigh fading. In this paper, and the sequel, new theoretical work has been contributed which substantially enhances existing performance analysis formulations. Major contributions include: substantial computational complexity reduction, including a priori BER accuracy bounding; an analytical approach that facilitates performance evaluation for systems with arbitrary spectral spreading distributions, with non-uniform transmission delay distributions. Using prior results, augmented by these enhancements, a generalized DS-CDMA system model is constructed and used to evaluated the BER performance, in a variety of scenarios. In this paper, the generalized system modeling was used to evaluate the performance of both Walsh- Hadamard (WH) and Walsh-Hadamard-seeded zero-correlation-zone (WH-ZCZ) coding. The selection of these codes was informed by the observation that WH codes contain N spectral spreading values (0 to N - 1), one for each code sequence; while WH-ZCZ codes contain only two spectral spreading values (N/2 - 1,N/2); where N is the sequence length in chips. Since these codes span the spectral spreading range for DS-CDMA coding, by invoking an induction argument, the generalization of the system model is sufficiently supported. The results in this paper, and the sequel, support the claim that an arbitrary accurate performance analysis for DS-CDMA systems can be evaluated over the full range of binary coding, with minimal computational complexity.

Load control strategies in 2G mobile network for W-CDMA radio ...

African Journals Online (AJOL)

Network planning requires a faithful analysis of each individual cell's capacity. In this paper, we examine load control equations as a resource allocation tool to analyse cell capacity for the uplink and downlink of Wideband Code Division Multiple Access (W-CDMA) networks. In the uplink, the noise rise is a parameter of ...

Wireless telecommunication systems

CERN Document Server

Terré, Michel; Vivier, Emmanuelle

2013-01-01

Wireless telecommunication systems generate a huge amount of interest. In the last two decades, these systems have experienced at least three major technological leaps, and it has become impossible to imagine how society was organized without them. In this book, we propose a macroscopic approach on wireless systems, and aim at answering key questions about power, data rates, multiple access, cellular engineering and access networks architectures.We present a series of solved problems, whose objective is to establish the main elements of a global link budget in several radiocommunicati

Optical wireless connected objects for healthcare.

Science.gov (United States)

Toumieux, Pascal; Chevalier, Ludovic; Sahuguède, Stéphanie; Julien-Vergonjanne, Anne

2015-10-01

In this Letter the authors explore the communication capabilities of optical wireless technology for a wearable device dedicated to healthcare application. In an indoor environment sensible to electromagnetic perturbations such as a hospital, the use of optical wireless links can permit reducing the amount of radio frequencies in the patient environment. Moreover, this technology presents the advantage to be secure, low-cost and easy to deploy. On the basis of commercially available components, a custom-made wearable device is presented, which allows optical wireless transmission of accelerometer data in the context of physical activity supervision of post-stroke patients in hospital. Considering patient mobility, the experimental performance is established in terms of packet loss as a function of the number of receivers fixed to the ceiling. The results permit to conclude that optical wireless links can be used to perform such mobile remote monitoring applications. Moreover, based on the measurements obtained with one receiver, it is possible to theoretically determine the performance according to the number of receivers to be deployed.

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 ...

Iterative Soft Decision Interference Cancellation for DS-CDMA Employing the Distribution of Interference

Directory of Open Access Journals (Sweden)

Gerstacker WolfgangH

2010-01-01

Full Text Available A well-known receiver strategy for direct-sequence code-division multiple-access (DS-CDMA transmission is iterative soft decision interference cancellation. For calculation of soft estimates used for cancellation, the distribution of residual interference is commonly assumed to be Gaussian. In this paper, we analyze matched filter-based iterative soft decision interference cancellation (MF ISDIC when utilizing an approximation of the actual probability density function (pdf of residual interference. In addition, a hybrid scheme is proposed, which reduces computational complexity by considering the strongest residual interferers according to their pdf while the Gaussian assumption is applied to the weak residual interferers. It turns out that the bit error ratio decreases already noticeably when only a small number of residual interferers is regarded according to their pdf. For the considered DS-CDMA transmission the bit error ratio decreases by 80% for high signal-to-noise ratios when modeling all residual interferers but the strongest three to be Gaussian distributed.

Small Worlds in the Tree Topologies of Wireless Sensor Networks

DEFF Research Database (Denmark)

Qiao, Li; Lingguo, Cui; Baihai, Zhang

2010-01-01

In this study, the characteristics of small worlds are investigated in the context of the tree topologies of wireless sensor networks. Tree topologies, which construct spatial graphs with larger characteristic path lengths than random graphs and small clustering coefficients, are ubiquitous...... in wireless sensor networks. Suffering from the link rewiring or the link addition, the characteristic path length of the tree topology reduces rapidly and the clustering coefficient increases greatly. The variety of characteristic path length influences the time synchronization characteristics of wireless...... sensor networks greatly. With the increase of the link rewiring or the link addition probability, the time synchronization error decreases drastically. Two novel protocols named LEACH-SW and TREEPSI-SW are proposed to improve the performances of the sensor networks, in which the small world...

Adaptive Wavelet Coding Applied in a Wireless Control System.

Science.gov (United States)

Gama, Felipe O S; Silveira, Luiz F Q; Salazar, Andrés O

2017-12-13

Wireless control systems can sense, control and act on the information exchanged between the wireless sensor nodes in a control loop. However, the exchanged information becomes susceptible to the degenerative effects produced by the multipath propagation. In order to minimize the destructive effects characteristic of wireless channels, several techniques have been investigated recently. Among them, wavelet coding is a good alternative for wireless communications for its robustness to the effects of multipath and its low computational complexity. This work proposes an adaptive wavelet coding whose parameters of code rate and signal constellation can vary according to the fading level and evaluates the use of this transmission system in a control loop implemented by wireless sensor nodes. The performance of the adaptive system was evaluated in terms of bit error rate (BER) versus E b / N 0 and spectral efficiency, considering a time-varying channel with flat Rayleigh fading, and in terms of processing overhead on a control system with wireless communication. The results obtained through computational simulations and experimental tests show performance gains obtained by insertion of the adaptive wavelet coding in a control loop with nodes interconnected by wireless link. These results enable the use of this technique in a wireless link control loop.

Adaptive Wavelet Coding Applied in a Wireless Control System

Directory of Open Access Journals (Sweden)

Felipe O. S. Gama

2017-12-01

Full Text Available Wireless control systems can sense, control and act on the information exchanged between the wireless sensor nodes in a control loop. However, the exchanged information becomes susceptible to the degenerative effects produced by the multipath propagation. In order to minimize the destructive effects characteristic of wireless channels, several techniques have been investigated recently. Among them, wavelet coding is a good alternative for wireless communications for its robustness to the effects of multipath and its low computational complexity. This work proposes an adaptive wavelet coding whose parameters of code rate and signal constellation can vary according to the fading level and evaluates the use of this transmission system in a control loop implemented by wireless sensor nodes. The performance of the adaptive system was evaluated in terms of bit error rate (BER versus E b / N 0 and spectral efficiency, considering a time-varying channel with flat Rayleigh fading, and in terms of processing overhead on a control system with wireless communication. The results obtained through computational simulations and experimental tests show performance gains obtained by insertion of the adaptive wavelet coding in a control loop with nodes interconnected by wireless link. These results enable the use of this technique in a wireless link control loop.

Scintillation index and performance analysis of wireless optical links over non-Kolmogorov weak turbulence based on generalized atmospheric spectral model.

Science.gov (United States)

Cang, Ji; Liu, Xu

2011-09-26

Based on the generalized spectral model for non-Kolmogorov atmospheric turbulence, analytic expressions of the scintillation index (SI) are derived for plane, spherical optical waves and a partially coherent Gaussian beam propagating through non-Kolmogorov turbulence horizontally in the weak fluctuation regime. The new expressions relate the SI to the finite turbulence inner and outer scales, spatial coherence of the source and spectral power-law and then used to analyze the effects of atmospheric condition and link length on the performance of wireless optical communication links. © 2011 Optical Society of America

Performance Evaluation of Underwater Wireless Optical Communications Links in the Presence of Different Air Bubble Populations

KAUST Repository

Oubei, Hassan M.; Elafandy, Rami T.; Park, Kihong; Ng, Tien Khee; Alouini, Mohamed-Slim; Ooi, Boon S.

2017-01-01

We experimentally evaluate the performance of underwater wireless optical communication (UWOC) links in the presence of different air bubbles. Air bubbles of different sizes and densities are generated by using an air pipe in conjunction with a submersible water pump of variable flow rate that help break up large bubbles into smaller bubbles. Received signal intensity measurements show that bubbles significantly degrade the performance of UWOC links. Large bubbles completely obstruct the optical beam and cause a deep fade. However, as the bubble size decreases, the level of deep fade also decreases because the optical beam is less susceptible to complete obstruction and more light reaches the detector. We also show that beam expansion could help mitigate the performance degradation due to the deep fade caused by air bubbles scatters in the channel.

Performance Evaluation of Underwater Wireless Optical Communications Links in the Presence of Different Air Bubble Populations

KAUST Repository

Oubei, Hassan M.

2017-03-16

We experimentally evaluate the performance of underwater wireless optical communication (UWOC) links in the presence of different air bubbles. Air bubbles of different sizes and densities are generated by using an air pipe in conjunction with a submersible water pump of variable flow rate that help break up large bubbles into smaller bubbles. Received signal intensity measurements show that bubbles significantly degrade the performance of UWOC links. Large bubbles completely obstruct the optical beam and cause a deep fade. However, as the bubble size decreases, the level of deep fade also decreases because the optical beam is less susceptible to complete obstruction and more light reaches the detector. We also show that beam expansion could help mitigate the performance degradation due to the deep fade caused by air bubbles scatters in the channel.

A Power-Efficient Wireless Capacitor Charging System Through an Inductive Link.

Science.gov (United States)

Lee, Hyung-Min; Ghovanloo, Maysam

2013-10-01

A power-efficient wireless capacitor charging system for inductively powered applications has been presented. A bank of capacitors can be directly charged from an ac source by generating a current through a series charge injection capacitor and a capacitor charger circuit. The fixed charging current reduces energy loss in switches, while maximizing the charging efficiency. An adaptive capacitor tuner compensates for the resonant capacitance variations during charging to keep the amplitude of the ac input voltage at its peak. We have fabricated the capacitor charging system prototype in a 0.35- μ m 4-metal 2-poly standard CMOS process in 2.1 mm 2 of chip area. It can charge four pairs of capacitors sequentially. While receiving 2.7-V peak ac input through a 2-MHz inductive link, the capacitor charging system can charge each pair of 1 μ F capacitors up to ±2 V in 420 μ s, achieving a high measured charging efficiency of 82%.

An efficient CDMA decoder for correlated information sources

International Nuclear Information System (INIS)

Efraim, Hadar; Yacov, Nadav; Kanter, Ido; Shental, Ori

2009-01-01

We consider the detection of correlated information sources in the ubiquitous code-division multiple-access (CDMA) scheme. We propose a message-passing based scheme for detecting correlated sources directly, with no need for source coding. The detection is done simultaneously over a block of transmitted binary symbols (word). Simulation results are provided, demonstrating a substantial improvement in bit error rate in comparison with the unmodified detector and the alternative of source compression. The robustness of the error-performance improvement is shown under practical model settings, including wrong estimation of the generating Markov transition matrix and finite-length spreading codes

Flexible Transmission Scheme for 4G Wireless Systems with Multiple Antennas

Directory of Open Access Journals (Sweden)

Horlin François

2005-01-01

Full Text Available New air interfaces are currently being developed to meet the high requirements of the emerging wireless communication systems. In this context, the combinations of the multicarrier (MC and spread-spectrum (SS technologies are promising candidates. In this paper, we propose a generic transmission scheme that allows to instantiate all the combinations of orthogonal frequency-division multiplexing (OFDM and cyclic-prefixed single-carrier (SC modulations with direct-sequence code-division multiple access (DS-CDMA. The generic transmission scheme is extended to integrate the space-division multiplexing (SDM and the orthogonal space-time block coding (STBC. Based on a generalized matrix model, the linear frequency-domain minimum mean square error (MMSE joint detector is derived. A mode selection strategy for up- and downlink is advised that efficiently trades off the cost of the mobile terminal and the achieved performance of a high-mobility cellular system. It is demonstrated that an adaptive transceiver that supports the proposed communication modes is necessary to track the changing communication conditions.

An analytical model for CDMA downlink rate optimization taking into account uplink coverage restriction

NARCIS (Netherlands)

Endrayanto, A.I.; van den Berg, Hans Leo; Boucherie, Richardus J.

2003-01-01

This paper models and analyzes downlink and uplink power assignment in Code Division Multiple Access (CDMA) mobile networks. By discretizing the area into small segments, the power requirements are characterized via a matrix representation that separates user and system characteristics. We obtain a

An analytical model for CDMA downlink rate optimization taking into account uplink coverage restrictions

NARCIS (Netherlands)

Endrayanto, A.I.; van den Berg, Hans Leo; Boucherie, Richardus J.

2005-01-01

This paper models and analyzes downlink and uplink power assignment in code division multiple access (CDMA) mobile networks. By discretizing the area into small segments, the power requirements are characterized via a matrix representation that separates user and system characteristics. We obtain a

Implanted Antennas in Medical Wireless Communications

CERN Document Server

Rahmat-Samii, Yahya; Balanis, Constantine

2006-01-01

Implanted Antennas in Medical Wireless Communications summarizes the results of recent research activities on the subject of implanted antennas for medical wireless communication systems. It is anticipated that in the near future sophisticated medical devices will be implanted inside the human body for medical telemetry and telemedicine. To establish effective and efficient wireless links with these devices, it is pivotal to give special attention to antenna designs that are low profile, small, safe, and cost effective. In this book, authors Yahya Rahmat-Samii and Jaehoon Kim demonstrate how a

Buckshot Routing with Distance Vectors in Three Application Scenarios for Wireless Sensor Networks with Unstable Network Topologies and Unidirectional Links

Directory of Open Access Journals (Sweden)

Reinhardt Karnapke

2015-02-01

Full Text Available Experiments have shown that the number of asymmetric and unidirectional links often exceeds the number of bidirectional ones, especially in the transitional area of the communication range of wireless sensor nodes. Still, most of today’s routing protocols ignore their existence or try to remove their implications. Also, links are not stable over time, and routes become unusable often, resulting in a need for new routing protocols that can handle highly dynamic links and use unidirectional links to their advantage. At SENSORCOMM' 2014, we presented BuckshotDV, a routing protocol which is resilient against link fluctuations and uses the longer reach of unidirectional links to increase its performance. Furthermore, its distance vector nature makes it scalable for large sensor networks. This paper is an extended version which adds some implementation details and the evaluation of BuckshotDV in two more application scenarios.

Neurological abnormalities associated with CDMA exposure.

Science.gov (United States)

Hocking, B; Westerman, R

2001-09-01

Dysaesthesiae of the scalp and neurological abnormality after mobile phone use have been reported previously, but the roles of the phone per se or the radiations in causing these findings have been questioned. We report finding a neurological abnormality in a patient after accidental exposure of the left side of the face to mobile phone radiation [code division multiple access (CDMA)] from a down-powered mobile phone base station antenna. He had headaches, unilateral left blurred vision and pupil constriction, unilateral altered sensation on the forehead, and abnormalities of current perception thresholds on testing the left trigeminal ophthalmic nerve. His nerve function recovered during 6 months follow-up. His exposure was 0.015-0.06 mW/cm(2) over 1-2 h. The implications regarding health effects of radiofrequency radiation are discussed.

Computationally Efficient Blind Code Synchronization for Asynchronous DS-CDMA Systems with Adaptive Antenna Arrays

Directory of Open Access Journals (Sweden)

Chia-Chang Hu

2005-04-01

Full Text Available A novel space-time adaptive near-far robust code-synchronization array detector for asynchronous DS-CDMA systems is developed in this paper. There are the same basic requirements that are needed by the conventional matched filter of an asynchronous DS-CDMA system. For the real-time applicability, a computationally efficient architecture of the proposed detector is developed that is based on the concept of the multistage Wiener filter (MWF of Goldstein and Reed. This multistage technique results in a self-synchronizing detection criterion that requires no inversion or eigendecomposition of a covariance matrix. As a consequence, this detector achieves a complexity that is only a linear function of the size of antenna array (J, the rank of the MWF (M, the system processing gain (N, and the number of samples in a chip interval (S, that is, 𝒪(JMNS. The complexity of the equivalent detector based on the minimum mean-squared error (MMSE or the subspace-based eigenstructure analysis is a function of 𝒪((JNS3. Moreover, this multistage scheme provides a rapid adaptive convergence under limited observation-data support. Simulations are conducted to evaluate the performance and convergence behavior of the proposed detector with the size of the J-element antenna array, the amount of the L-sample support, and the rank of the M-stage MWF. The performance advantage of the proposed detector over other DS-CDMA detectors is investigated as well.

Photonic techniques for sub-Terahertz wireless data transmission

DEFF Research Database (Denmark)

Tafur Monroy, Idelfonso

2015-01-01

Wireless data communication links with capacities beyond 100 Gbit/s will require operating at sub-Terahertz frequencies using a large bandpass bandwidth facing new engineering challenges. We review several implementation aspects by using photonic technologies. © 2015 OSA.......Wireless data communication links with capacities beyond 100 Gbit/s will require operating at sub-Terahertz frequencies using a large bandpass bandwidth facing new engineering challenges. We review several implementation aspects by using photonic technologies. © 2015 OSA....

Successive Interference Cancellation for DS-CDMA Systems with Transmit Diversity

Directory of Open Access Journals (Sweden)

Li Wei

2004-01-01

Full Text Available We introduce a new successive interference cancellation (SIC technique for direct sequence code division multiple access (DS-CDMA systems with transmit diversity. The transmit diversity is achieved with a space-time block code (STBC. In our work we first consider hard decision SIC with an STBC, and then investigate the performance of soft decision SIC with an STBC. System performance over a Rayleigh fading channel is investigated and the analysis is confirmed by simulation.

Introductory survey for wireless infrared communications

Directory of Open Access Journals (Sweden)

Munsif Ali Jatoi

2014-08-01

Full Text Available Wireless infrared communications can be defined as the propagation of light waves in free space using infrared radiation whose range is 400–700 nm. This range corresponds to frequencies of hundreds of terahertz, which is high for higher data rate applications. Wireless infrared is applied for higher data rates applications such as wireless computing, wireless video and wireless multimedia communication applications. Introduced by Gfeller, this field has grown with different link configurations, improved transmitter efficiency, increased receiver responsivity and various multiple access techniques for improved quality. Errors are caused because of background light, which causes degradation overall system performance. Error correction techniques are used to remove the errors caused during transmission. This study provides a brief account on field theory used for error correction in wireless infrared systems. The results are produced in terms of bit error rate and signal-to-noise ratio for various bit lengths to show the ability of encoding and decoding algorithms.

Nonlinear Optimization-Based Device-Free Localization with Outlier Link Rejection

Directory of Open Access Journals (Sweden)

Wendong Xiao

2015-04-01

Full Text Available Device-free localization (DFL is an emerging wireless technique for estimating the location of target that does not have any attached electronic device. It has found extensive use in Smart City applications such as healthcare at home and hospitals, location-based services at smart spaces, city emergency response and infrastructure security. In DFL, wireless devices are used as sensors that can sense the target by transmitting and receiving wireless signals collaboratively. Many DFL systems are implemented based on received signal strength (RSS measurements and the location of the target is estimated by detecting the changes of the RSS measurements of the wireless links. Due to the uncertainty of the wireless channel, certain links may be seriously polluted and result in erroneous detection. In this paper, we propose a novel nonlinear optimization approach with outlier link rejection (NOOLR for RSS-based DFL. It consists of three key strategies, including: (1 affected link identification by differential RSS detection; (2 outlier link rejection via geometrical positional relationship among links; (3 target location estimation by formulating and solving a nonlinear optimization problem. Experimental results demonstrate that NOOLR is robust to the fluctuation of the wireless signals with superior localization accuracy compared with the existing Radio Tomographic Imaging (RTI approach.

A Wireless Implantable Switched-Capacitor Based Optogenetic Stimulating System

Science.gov (United States)

Lee, Hyung-Min; Kwon, Ki-Yong; Li, Wen

2015-01-01

This paper presents a power-efficient implantable optogenetic interface using a wireless switched-capacitor based stimulating (SCS) system. The SCS efficiently charges storage capacitors directly from an inductive link and periodically discharges them into an array of micro-LEDs, providing high instantaneous power without affecting wireless link and system supply voltage. A custom-designed computer interface in LabVIEW environment wirelessly controls stimulation parameters through the inductive link, and an optrode array enables simultaneous neural recording along with optical stimulation. The 4-channel SCS system prototype has been implemented in a 0.35-μm CMOS process and combined with the optrode array. In vivo experiments involving light-induced local field potentials verified the efficacy of the SCS system. An implantable version of the SCS system with flexible hermetic sealing is under development for chronic experiments. PMID:25570099

What is a missing link among wireless persistent surveillance?

Science.gov (United States)

Hsu, Charles; Szu, Harold

2011-06-01

The next generation surveillance system will equip with versatile sensor devices and information focus capable of conducting regular and irregular surveillance and security environments worldwide. The community of the persistent surveillance must invest the limited energy and money effectively into researching enabling technologies such as nanotechnology, wireless networks, and micro-electromechanical systems (MEMS) to develop persistent surveillance applications for the future. Wireless sensor networks can be used by the military for a number of purposes such as monitoring militant activity in remote areas and force protection. Being equipped with appropriate sensors these networks can enable detection of enemy movement, identification of enemy force and analysis of their movement and progress. Among these sensor network technologies, covert communication is one of the challenging tasks in the persistent surveillance because it is highly demanded to provide secured sensor nodes and linkage for fear of deliberate sabotage. Due to the matured VLSI/DSP technologies, affordable COTS of UWB technology with noise-like direct sequence (DS) time-domain pulses is a potential solution to support low probability of intercept and low probability of detection (LPI/LPD) data communication and transmission. This paper will describe a number of technical challenges in wireless persistent surveillance development include covert communication, network control and routing, collaborating signal and information processing, and etc. The paper concludes by presenting Hermitian Wavelets to enhance SNR in support of secured communication.

A multiple-choice knapsack based algorithm for CDMA downlink rate differentiation under uplink coverage restrictions

NARCIS (Netherlands)

Endrayanto, A.I.; Bumb, A.F.; Boucherie, Richardus J.

2004-01-01

This paper presents an analytical model for downlink rate allocation in Code Division Multiple Access (CDMA) mobile networks. By discretizing the coverage area into small segments, the transmit power requirements are characterized via a matrix representation that separates user and system

SIMULASI TEKNIK POWER CONTROL DAN MULTI USER DETECTION PADA SISTEM KOMUNIKASI DS-CDMA

Directory of Open Access Journals (Sweden)

Yuli Christyono

2012-02-01

Full Text Available CDMA is interference limited multiple access system. Because all users transmit on the same frequency,internal interference generated by the system is the most significant factor in determining system capacity andcall quality. The transmit power for each user must be reduced to limit interference, however, the power shouldbe enough to maintain the required Eb/No (signal to noise ratio for a satisfactory call quality. Maximumcapacity is achieved when Eb/No of every user is at the minimum level needed for the acceptable channelperformance. As the MS moves around, the RF environment continuously changes due to fast and slow fading,external interference, shadowing , and other factors. The aim of the dynamic power control is to limittransmitted power on both the links while maintaining link quality under all conditions. Additional advantagesare longer mobile battery life and longer life span of BTS power amplifiers.In this research will be made a sumulation of power control and multi user detection to avoid the interferencebetween MS.Observations show that the increasing number of users will decrease the value of Signal to Interfrence Ratio(SIR / SIR below the target. To cope the growing number of users increases can be done by iteration / updatingpower transmit so the convergence computation can be reached and target value SIR can be achieved. Inaddition, to reduce interference can also be done by extending the number of chips.

Performance of Turbo Interference Cancellation Receivers in Space-Time Block Coded DS-CDMA Systems

Directory of Open Access Journals (Sweden)

Emmanuel Oluremi Bejide

2008-07-01

Full Text Available We investigate the performance of turbo interference cancellation receivers in the space time block coded (STBC direct-sequence code division multiple access (DS-CDMA system. Depending on the concatenation scheme used, we divide these receivers into the partitioned approach (PA and the iterative approach (IA receivers. The performance of both the PA and IA receivers is evaluated in Rayleigh fading channels for the uplink scenario. Numerical results show that the MMSE front-end turbo space-time iterative approach receiver (IA effectively combats the mixture of MAI and intersymbol interference (ISI. To further investigate the possible achievable data rates in the turbo interference cancellation receivers, we introduce the puncturing of the turbo code through the use of rate compatible punctured turbo codes (RCPTCs. Simulation results suggest that combining interference cancellation, turbo decoding, STBC, and RCPTC can significantly improve the achievable data rates for a synchronous DS-CDMA system for the uplink in Rayleigh flat fading channels.

Compensating for Channel Fading in DS-CDMA Communication Systems Employing ICA Neural Network Detectors

Directory of Open Access Journals (Sweden)

David Overbye

2005-06-01

Full Text Available In this paper we examine the impact of channel fading on the bit error rate of a DS-CDMA communication system. The system employs detectors that incorporate neural networks effecting methods of independent component analysis (ICA, subspace estimation of channel noise, and Hopfield type neural networks. The Rayleigh fading channel model is used. When employed in a Rayleigh fading environment, the ICA neural network detectors that give superior performance in a flat fading channel did not retain this superior performance. We then present a new method of compensating for channel fading based on the incorporation of priors in the ICA neural network learning algorithms. When the ICA neural network detectors were compensated using the incorporation of priors, they give significantly better performance than the traditional detectors and the uncompensated ICA detectors. Keywords: CDMA, Multi-user Detection, Rayleigh Fading, Multipath Detection, Independent Component Analysis, Prior Probability Hebbian Learning, Natural Gradient

Wireless Communications in the Era of Big Data

OpenAIRE

Bi, Suzhi; Zhang, Rui; Ding, Zhi; Cui, Shuguang

2015-01-01

© 1979-2012 IEEE. The rapidly growing wave of wireless data service is pushing against the boundary of our communication network's processing power. The pervasive and exponentially increasing data traffic present imminent challenges to all aspects of wireless system design, such as spectrum efficiency, computing capabilities, and fronthaul/backhaul link capacity. In this article, we discuss the challenges and opportunities in the design of scalable wireless systems to embrace the big data era...

Performance Analysis of New Binary User Codes for DS-CDMA Communication

Science.gov (United States)

Usha, Kamle; Jaya Sankar, Kottareddygari

2016-03-01

This paper analyzes new binary spreading codes through correlation properties and also presents their performance over additive white Gaussian noise (AWGN) channel. The proposed codes are constructed using gray and inverse gray codes. In this paper, a n-bit gray code appended by its n-bit inverse gray code to construct the 2n-length binary user codes are discussed. Like Walsh codes, these binary user codes are available in sizes of power of two and additionally code sets of length 6 and their even multiples are also available. The simple construction technique and generation of code sets of different sizes are the salient features of the proposed codes. Walsh codes and gold codes are considered for comparison in this paper as these are popularly used for synchronous and asynchronous multi user communications respectively. In the current work the auto and cross correlation properties of the proposed codes are compared with those of Walsh codes and gold codes. Performance of the proposed binary user codes for both synchronous and asynchronous direct sequence CDMA communication over AWGN channel is also discussed in this paper. The proposed binary user codes are found to be suitable for both synchronous and asynchronous DS-CDMA communication.

Analysis of Optical CDMA Signal Transmission: Capacity Limits and Simulation Results

Directory of Open Access Journals (Sweden)

Lawrence R. Chen

2005-06-01

Full Text Available We present performance limits of the optical code-division multiple-access (OCDMA networks. In particular, we evaluate the information-theoretical capacity of the OCDMA transmission when single-user detection (SUD is used by the receiver. First, we model the OCDMA transmission as a discrete memoryless channel, evaluate its capacity when binary modulation is used in the interference-limited (noiseless case, and extend this analysis to the case when additive white Gaussian noise (AWGN is corrupting the received signals. Next, we analyze the benefits of using nonbinary signaling for increasing the throughput of optical CDMA transmission. It turns out that up to a fourfold increase in the network throughput can be achieved with practical numbers of modulation levels in comparison to the traditionally considered binary case. Finally, we present BER simulation results for channel coded binary and M-ary OCDMA transmission systems. In particular, we apply turbo codes concatenated with Reed-Solomon codes so that up to several hundred concurrent optical CDMA users can be supported at low target bit error rates. We observe that unlike conventional OCDMA systems, turbo-empowered OCDMA can allow overloading (more active users than is the length of the spreading sequences with good bit error rate system performance.

Analysis of Optical CDMA Signal Transmission: Capacity Limits and Simulation Results

Science.gov (United States)

Garba, Aminata A.; Yim, Raymond M. H.; Bajcsy, Jan; Chen, Lawrence R.

2005-12-01

We present performance limits of the optical code-division multiple-access (OCDMA) networks. In particular, we evaluate the information-theoretical capacity of the OCDMA transmission when single-user detection (SUD) is used by the receiver. First, we model the OCDMA transmission as a discrete memoryless channel, evaluate its capacity when binary modulation is used in the interference-limited (noiseless) case, and extend this analysis to the case when additive white Gaussian noise (AWGN) is corrupting the received signals. Next, we analyze the benefits of using nonbinary signaling for increasing the throughput of optical CDMA transmission. It turns out that up to a fourfold increase in the network throughput can be achieved with practical numbers of modulation levels in comparison to the traditionally considered binary case. Finally, we present BER simulation results for channel coded binary and[InlineEquation not available: see fulltext.]-ary OCDMA transmission systems. In particular, we apply turbo codes concatenated with Reed-Solomon codes so that up to several hundred concurrent optical CDMA users can be supported at low target bit error rates. We observe that unlike conventional OCDMA systems, turbo-empowered OCDMA can allow overloading (more active users than is the length of the spreading sequences) with good bit error rate system performance.

Cellular responses to 836 MHz and 1,765 GHz CDMA radiations

International Nuclear Information System (INIS)

Park, Woong Yang; Seo, Jeong Sun; Paik, Jung Ki; Lim, Kye Jae; Yoon, Hyun Bo

2002-01-01

The effect of radiofrequency (RF) radiation in the cellular phone communication range (836.5 MHz and 1.765 GHz code division multiple access, CDMA) on tumorigenesis and other health effect was measured using the in vitro cell culture system. To determine whether 836.5 MHz or 1.765 GHz CDMA radiations have any genotoxic effects to induce neoplastic transformation, C3H 10T1/2 cells were exposed to either of the above radiations at a specific absorption rate (SAR) of 35.6W/Kg (836.5 MHz) and 38.2 W/kg(1.765 GHz) or sham- exposed at the same time for 7 days. Cells were maintained in incubators and refed with fresh growth medium every 3 days. At this SAR, radiofrequency radiation did not induce neoplastic transformation in vitro. The extent of alteration in the kinetics of cell proliferation indicated no significant differences between RF-radiation- and sham-exposed cells with respect to MTS assay and 8-OHdG. Under this experimental conditions tested, there is no evidence for the induction of genotoxic indices in human and mouse cells exposed in vitro for 7 days to 836.5 MHz or 1.765 GHz RF radiation at SARs of up to 35.6 or 38.2 W/kg

Wireless Device-to-Device (D2D) Links for Machine-to-Machine (M2M) Communication

DEFF Research Database (Denmark)

Pratas, Nuno; Popovski, Petar

2017-01-01

Device-to-Device (D2D) communications will play an important role in the fifth generation (5G) cellular networks, by increasing the spatial reuse of spectrum resources and enabling communication links with low latency. D2D is composed of two fundamental building blocks: proximity discovery...... and direct communication between nearby users. Another emerging trend in wireless cellular systems is Machine-to-Machine (M2M) communications, often characterized by fixed, low transmission rates. In this chapter we motivate the synergy between D2D and M2M, and present technologies that enable M2M-via-D2D...

A Low-Complexity Joint Synchronization and Detection Algorithm for Single-Band DS-CDMA UWB Communications

DEFF Research Database (Denmark)

Christensen, Lars P.B.

2005-01-01

The problem of asynchronous direct-sequence code division multiple access (DS-CDMA) detection over the ultra-wideband (UWB) multipath channel is considered. A joint synchronization, channel-estimation and multi-user detection scheme based on the adaptive linear minimum mean-square error (LMMSE...

Space-Time Chip Equalization for Maximum Diversity Space-Time Block Coded DS-CDMA Downlink Transmission

NARCIS (Netherlands)

Leus, G.; Petré, F.; Moonen, M.

2004-01-01

In the downlink of DS-CDMA, frequency-selectivity destroys the orthogonality of the user signals and introduces multiuser interference (MUI). Space-time chip equalization is an efficient tool to restore the orthogonality of the user signals and suppress the MUI. Furthermore, multiple-input

An Improved Overloading Scheme for Downlink CDMA

Directory of Open Access Journals (Sweden)

Marc Moeneclaey

2005-04-01

Full Text Available An improved overloading scheme is presented for single-user detection in the downlink of multiple-access systems based on OCDMA/OCDMA (O/O. By displacing in time the orthogonal signatures of the two user sets that make up the overloaded system, the cross-correlation between the users of the two sets is reduced. For random O/O with square-root cosine rolloff chip pulses, the multiuser interference can be decreased by up to 50% (depending on the chip pulse bandwidth as compared to quasiorthogonal sequences (QOS that are presently part of the downlink standard of Cdma2000. This reduction of the multiuser interference gives rise to an increase of the achievable signal-to-interference-plus-noise ratio for a particular channel load.

Two-Step Fair Scheduling of Continuous Media Streams over Error-Prone Wireless Channels

Science.gov (United States)

Oh, Soohyun; Lee, Jin Wook; Park, Taejoon; Jo, Tae-Chang

In wireless cellular networks, streaming of continuous media (with strict QoS requirements) over wireless links is challenging due to their inherent unreliability characterized by location-dependent, bursty errors. To address this challenge, we present a two-step scheduling algorithm for a base station to provide streaming of continuous media to wireless clients over the error-prone wireless links. The proposed algorithm is capable of minimizing the packet loss rate of individual clients in the presence of error bursts, by transmitting packets in the round-robin manner and also adopting a mechanism for channel prediction and swapping.

The Prospects of Ultra-Broadband THz Wireless Communications

DEFF Research Database (Denmark)

Yu, Xianbin; Chen, Ying; Galili, Michael

2014-01-01

Wireless communications have entered into a path towards Terabit era, to accommodate the increasing demands on fast wireless access, e.g. huge data file transferring and fast mobile data access. Terahertz (THz) technology is considered feasible to carry ultrafast data signals, as it offers up...... to a few THz bandwidths. This paper overviews the prospects of Tbit/s wireless data rate and their potential applications. Technically, this talk reviews the key technologies and challenges to achieve an ultrafast wireless system operating in the THz frequency band, from viewpoint of communication......, in terms of ultrafast THz generation/THz detection and link power budget....

Quadrature amplitude modulation from basics to adaptive trellis-coded turbo-equalised and space-time coded OFDM CDMA and MC-CDMA systems

CERN Document Server

Hanzo, Lajos

2004-01-01

"Now fully revised and updated, with more than 300 pages of new material, this new edition presents the wide range of recent developments in the field and places particular emphasis on the family of coded modulation aided OFDM and CDMA schemes. In addition, it also includes a fully revised chapter on adaptive modulation and a new chapter characterizing the design trade-offs of adaptive modulation and space-time coding." "In summary, this volume amalgamates a comprehensive textbook with a deep research monograph on the topic of QAM, ensuring it has a wide-ranging appeal for both senior undergraduate and postgraduate students as well as practicing engineers and researchers."--Jacket.

Information Assurance in Wireless Networks

Science.gov (United States)

Kabara, Joseph; Krishnamurthy, Prashant; Tipper, David

2001-09-01

Emerging wireless networks will contain a hybrid infrastructure based on fixed, mobile and ad hoc topologies and technologies. In such a dynamic architecture, we define information assurance as the provisions for both information security and information availability. The implications of this definition are that the wireless network architecture must (a) provide sufficient security measures, (b) be survivable under node or link attack or failure and (c) be designed such that sufficient capacity remains for all critical services (and preferably most other services) in the event of attack or component failure. We have begun a research project to investigate the provision of information assurance for wireless networks viz. survivability, security and availability and here discuss the issues and challenges therein.

Adaptive Protocols for Mobile Wireless Networks

National Research Council Canada - National Science Library

Pursley, Michael B

2005-01-01

.... Research results are presented on adaptive, energy-efficient, distributed protocols for mobile wireless networks that must operate effectively over unreliable communication links in highly dynamic...

Multigigabit W-Band (75–110 GHz) Bidirectional Hybrid Fiber-Wireless Systems in Access Networks

DEFF Research Database (Denmark)

Pang, Xiaodan; Lebedev, Alexander; Vegas Olmos, Juan José

2014-01-01

compare the transmission performances in terms of achievable wireless distances with and without using a high-frequency electrical power amplifier at the wireless transmitter. A downlink 16-Gbit/s QPSK signal and an uplink 1.25-Gbit/s ASK signal transmission over the two implementations are experimentally......We experimentally demonstrate multigigabit capacity bidirectional hybrid fiber-wireless systems with RF carrier frequencies at the W-band (75-110 GHz) that enables the seamless convergence between wireless and fiber-optic data transmission systems in access networks. In this study, we evaluate...... the transmission performances in two scenarios: a fiber-wireless access link that directly provide high-speed connections to wireless end users, and a fiber-wireless-fiber signal relay where a high capacity wireless link can be used to bridge two access fiber spans over physical obstacles. In both scenarios, we...

Underwater Optical Wireless Communications, Networking, and Localization: A Survey

KAUST Repository

Saeed, Nasir; Celik, Abdulkadir; Al-Naffouri, Tareq Y.; Alouini, Mohamed-Slim

2018-01-01

Underwater wireless communications can be carried out through acoustic, radio frequency (RF), and optical waves. Compared to its bandwidth limited acoustic and RF counterparts, underwater optical wireless communications (UOWCs) can support higher data rates at low latency levels. However, severe aquatic channel conditions (e.g., absorption, scattering, turbulence, etc.) pose great challenges for UOWCs and significantly reduce the attainable communication ranges, which necessitates efficient networking and localization solutions. Therefore, we provide a comprehensive survey on the challenges, advances, and prospects of underwater optical wireless networks (UOWNs) from a layer by layer perspective which includes: 1) Potential network architectures; 2) Physical layer issues including propagation characteristics, channel modeling, and modulation techniques 3) Data link layer problems covering link configurations, link budgets, performance metrics, and multiple access schemes; 4) Network layer topics containing relaying techniques and potential routing algorithms; 5) Transport layer subjects such as connectivity, reliability, flow and congestion control; 6) Application layer goals and state-of-the-art UOWN applications, and 7) Localization and its impacts on UOWN layers. Finally, we outline the open research challenges and point out the future directions for underwater optical wireless communications, networking, and localization research.

Underwater Optical Wireless Communications, Networking, and Localization: A Survey

KAUST Repository

Saeed, Nasir

2018-02-28

Underwater wireless communications can be carried out through acoustic, radio frequency (RF), and optical waves. Compared to its bandwidth limited acoustic and RF counterparts, underwater optical wireless communications (UOWCs) can support higher data rates at low latency levels. However, severe aquatic channel conditions (e.g., absorption, scattering, turbulence, etc.) pose great challenges for UOWCs and significantly reduce the attainable communication ranges, which necessitates efficient networking and localization solutions. Therefore, we provide a comprehensive survey on the challenges, advances, and prospects of underwater optical wireless networks (UOWNs) from a layer by layer perspective which includes: 1) Potential network architectures; 2) Physical layer issues including propagation characteristics, channel modeling, and modulation techniques 3) Data link layer problems covering link configurations, link budgets, performance metrics, and multiple access schemes; 4) Network layer topics containing relaying techniques and potential routing algorithms; 5) Transport layer subjects such as connectivity, reliability, flow and congestion control; 6) Application layer goals and state-of-the-art UOWN applications, and 7) Localization and its impacts on UOWN layers. Finally, we outline the open research challenges and point out the future directions for underwater optical wireless communications, networking, and localization research.

Infrared wireless data transfer for real-time motion control

NARCIS (Netherlands)

Gajdusek, M.; Overboom, T.T.; Damen, A.A.H.; Bosch, van den P.P.J.

2009-01-01

In this paper several wireless solution are compared for their suitability for real-time control of a fast motion system. From the comparison, Very Fast Infrared (VFIR) communication link has been found to be an attractive solution for presented wirelessly controlled manipulator. Because standard

Wireless communication for hearing aid system

DEFF Research Database (Denmark)

Nour, Baqer

This thesis focuses on the wireless coupling between hearing aids close to a human head. Hearing aids constitute devices withadvanced technology and the wireless communication enables the introduction of a range of completely new functionalities. Such devices are small and the available power...... the ear-to-ear wireless communication channel by understanding the mechanisms that control the propagations of the signals and the losses. The second objective isto investigate the properties of magneto-dielectric materials and their potential in antenna miniaturization. There are three approaches...... to study the ear-to-ear wireless communication link; a theoretical approach models the human head asa sphere that has the electrical properties of the head, a numerical approach implements a more realistic geometry of the head, and an experimental approach measures directly the coupling between...

Conjugate Image Theory Applied on Capacitive Wireless Power Transfer

OpenAIRE

Ben Minnaert; Nobby Stevens

2017-01-01

Wireless power transfer using a magnetic field through inductive coupling is steadily entering the market in a broad range of applications. However, for certain applications, capacitive wireless power transfer using electric coupling might be preferable. In order to obtain a maximum power transfer efficiency, an optimal compensation network must be designed at the input and output ports of the capacitive wireless link. In this work, the conjugate image theory is applied to determine this opti...

First satellite mobile communication trials using BLQS-CDMA

Science.gov (United States)

Luzdemateo, Maria; Johns, Simon; Dothey, Michel; Vanhimbeeck, Carl; Deman, Ivan; Wery, Bruno

1993-01-01

In this paper, technical results obtained in the first MSBN Land mobile technical trial are reported. MSBN (Mobile Satellite Business Network) is a new program undertaken by the European Space Agency (ESA) to promote mobile satellite communication in Europe, in particular voice capability. The first phase of the MSBN system implementation plan is an experimental phase. Its purpose is to evaluate through field experiments the performance of the MSBN system prior to finalization of its specifications. Particularly, the objective is to verify in the field and possibly improve the performance of the novel satellite access technique BLQS-CDMA (Band Limited Quasi-Synchronous-Code Division Multiple Access), which is proposed as baseline for the MSBN.

Combined single-mode/multimode fiber link supporting simplified in-building 60-GHz gigabit wireless access

DEFF Research Database (Denmark)

Pham, Tien Thang; Lebedev, Alexander; Beltrán, Marta

2012-01-01

In this paper, we propose and experimentally demonstrate a simple, cost-effective hybrid gigabit fiber-wireless system for in-building wireless access. Simplicity and cost-effectiveness are achieved in all parts of the system by utilizing direct laser modulation, optical frequency up-conversion, ......In this paper, we propose and experimentally demonstrate a simple, cost-effective hybrid gigabit fiber-wireless system for in-building wireless access. Simplicity and cost-effectiveness are achieved in all parts of the system by utilizing direct laser modulation, optical frequency up...

DEPLOYMENT OF ANTENNA ARRAY FOR DATA RETRIEVAL IN CDMA ENVIROMENT

OpenAIRE

RICARDO ZELENOVSKY

2001-01-01

Este trabalho de tese trata do emprego de arranjos de antenas em ambientes de comunicação móvel,dando-se ênfase ao canal de dados reverso do Sistema IS-95. Propõe-se dois estimadores: um para a direção de chegada dos sinais e outro para outros dados. Inicialmente é apresentado um estudo sobre arranjos de antenas e dos principais detalhes do sistema IS-95,especialmente a multiplicidade de acesso via divisão por códigos (CDMA).Aborda-se em seguida o problema d...

Theoretical Investigation into Spectral Coexistence of CDMA and TDMA Systems

Directory of Open Access Journals (Sweden)

A.M. Abbosh

2008-12-01

Full Text Available The scarcity of available radio spectrum presently limits the extension of modern multimedia systems. This paper presents a theoretical investigation into the possibility of using a frequency overlay of a narrowband Code Division Multiple Access (CDMA System and a Time Division Multiple Access (TDMA System to provide a greater spectral efficiency. This paper shows that under certain conditions the two systems can operate in the same frequency band and in the same area with a considerable improvement in the overall capacity of the whole system.

On Performance of Linear Multiuser Detectors for Wireless Multimedia Applications

Science.gov (United States)

Agarwal, Rekha; Reddy, B. V. R.; Bindu, E.; Nayak, Pinki

In this paper, performance of different multi-rate schemes in DS-CDMA system is evaluated. The analysis of multirate linear multiuser detectors with multiprocessing gain is analyzed for synchronous Code Division Multiple Access (CDMA) systems. Variable data rate is achieved by varying the processing gain. Our conclusion is that bit error rate for multirate and single rate systems can be made same with a tradeoff with number of users in linear multiuser detectors.

Methodology and Implementation on DSP of Heuristic Multiuser DS/CDMA Detectors

Directory of Open Access Journals (Sweden)

Alex Miyamoto Mussi

2010-12-01

Full Text Available The growing number of users of mobile communications networks and the scarcity of the electromagnetic spectrum make the use of diversity techniques and detection/decoding efficient, such as the use of multiple antennas at the transmitter and/or receiver, multiuser detection (MuD – Multiuser Detection, among others, have an increasingly prominent role in the telecommunications landscape. This paper presents a design methodology based on digital signal processors (DSP – Digital Signal Processor with a view to the implementation of multiuser heuristics detectors in systems DS/CDMA (Direct Sequence Code Division Multiple Access. Heuristics detection techniques result in near-optimal performance in order to approach the performance of maximum-likelihood (ML. In this work, was employed the DSP development platform called the C6713 DSK, which is based in Texas TMS320C6713 processor. The heuristics techniques proposed are based on well established algorithms in the literature. The efficiency of the algorithms implemented in DSP has been evaluated numerically by computing the measure of bit error rate (BER. Finally, the feasibility of implementation in DSP could then be verified by comparing results from multiple Monte-Carlo simulation in Matlab, with those obtained from implementation on DSP. It also demonstrates the effective increase in performance and system capacity of DS/CDMA with the use of heuristic multiuser detection techniques, implemented directly in the DSP.

Reactor building indoor wireless network channel quality estimation using RSSI measurement of wireless sensor network

International Nuclear Information System (INIS)

Merat, S.

2008-01-01

Expanding wireless communication network reception inside reactor buildings (RB) and service wings (SW) has always been a technical challenge for operations service team. This is driven by the volume of metal equipment inside the Reactor Buildings (RB) that blocks and somehow shields the signal throughout the link. In this study, to improve wireless reception inside the Reactor Building (RB), an experimental model using indoor localization mesh based on IEEE 802.15 is developed to implement a wireless sensor network. This experimental model estimates the distance between different nodes by measuring the RSSI (Received Signal Strength Indicator). Then by using triangulation and RSSI measurement, the validity of the estimation techniques is verified to simulate the physical environmental obstacles, which block the signal transmission. (author)

Reactor building indoor wireless network channel quality estimation using RSSI measurement of wireless sensor network

Energy Technology Data Exchange (ETDEWEB)

Merat, S. [Wardrop Engineering Inc., Toronto, Ontario (Canada)

2008-07-01

Expanding wireless communication network reception inside reactor buildings (RB) and service wings (SW) has always been a technical challenge for operations service team. This is driven by the volume of metal equipment inside the Reactor Buildings (RB) that blocks and somehow shields the signal throughout the link. In this study, to improve wireless reception inside the Reactor Building (RB), an experimental model using indoor localization mesh based on IEEE 802.15 is developed to implement a wireless sensor network. This experimental model estimates the distance between different nodes by measuring the RSSI (Received Signal Strength Indicator). Then by using triangulation and RSSI measurement, the validity of the estimation techniques is verified to simulate the physical environmental obstacles, which block the signal transmission. (author)

Cross-Layer Wireless Resource Allocation

National Research Council Canada - National Science Library

Berry, Randall A; Yeh, Edmund M

2005-01-01

.... This bit pipe is a simple abstraction of the underlying physical and data link layers. There is growing awareness that this simple bit-pipe view is inadequate, particularly in the context of modern wireless data networks...

Bandwidth enhancement of wireless optical communication link using a near-infrared laser over turbid underwater channel

KAUST Repository

Lee, It Ee

2017-11-30

Underwater wireless optical communication (UWOC) has been widely studied as a promising alternative to establish reliable short-range marine communication links. Microscopic particulates suspended in various ocean, harbor and natural waters will alter the propagation characteristics of the optical signals underwater. In this paper, we demonstrate a gigabit near-infrared (NIR)-based UWOC link using an 808-nm laser diode, to examine the feasibility of the proposed system in mitigating the particle scattering effect over turbid waters. We show that the NIR wavelengths presents greater resilience to the aqueous suspension of these micro-sized particles with a smaller scattering effect due to its longer wavelength, as evident by the smaller variations in the optical beam transmittance. It is also observed that the error performance is improved at higher concentrations albeit the significant reduction in received signal power. We further demonstrate that the overall frequency response of the system exhibits a bandwidth enhancement up to a few tens of MHz with increasing concentrations.

Joint Frequency-Domain Equalization and Despreading for Multi-Code DS-CDMA Using Cyclic Delay Transmit Diversity

Science.gov (United States)

Yamamoto, Tetsuya; Takeda, Kazuki; Adachi, Fumiyuki

Frequency-domain equalization (FDE) based on the minimum mean square error (MMSE) criterion can provide a better bit error rate (BER) performance than rake combining. To further improve the BER performance, cyclic delay transmit diversity (CDTD) can be used. CDTD simultaneously transmits the same signal from different antennas after adding different cyclic delays to increase the number of equivalent propagation paths. Although a joint use of CDTD and MMSE-FDE for direct sequence code division multiple access (DS-CDMA) achieves larger frequency diversity gain, the BER performance improvement is limited by the residual inter-chip interference (ICI) after FDE. In this paper, we propose joint FDE and despreading for DS-CDMA using CDTD. Equalization and despreading are simultaneously performed in the frequency-domain to suppress the residual ICI after FDE. A theoretical conditional BER analysis is presented for the given channel condition. The BER analysis is confirmed by computer simulation.

Blind Multiuser Detection by Kurtosis Maximization for Asynchronous Multirate DS/CDMA Systems

Directory of Open Access Journals (Sweden)

Peng Chun-Hsien

2006-01-01

Full Text Available Chi et al. proposed a fast kurtosis maximization algorithm (FKMA for blind equalization/deconvolution of multiple-input multiple-output (MIMO linear time-invariant systems. This algorithm has been applied to blind multiuser detection of single-rate direct-sequence/code-division multiple-access (DS/CDMA systems and blind source separation (or independent component analysis. In this paper, the FKMA is further applied to blind multiuser detection for multirate DS/CDMA systems. The ideas are to properly formulate discrete-time MIMO signal models by converting real multirate users into single-rate virtual users, followed by the use of FKMA for extraction of virtual users' data sequences associated with the desired user, and recovery of the data sequence of the desired user from estimated virtual users' data sequences. Assuming that all the users' spreading sequences are given a priori, two multirate blind multiuser detection algorithms (with either a single receive antenna or multiple antennas, which also enjoy the merits of superexponential convergence rate and guaranteed convergence of the FKMA, are proposed in the paper, one based on a convolutional MIMO signal model and the other based on an instantaneous MIMO signal model. Some simulation results are then presented to demonstrate their effectiveness and to provide a performance comparison with some existing algorithms.

Remote Access Unit for Optic-to-Wireless Conversion

DEFF Research Database (Denmark)

Chorchos, Łukasz; Rommel, Simon; Turkiewicz, J. P.

. Growing demand for high speed wireless data transmission and new wireless standards like 5G force network operators to find new solutions for backhaul networks. Presently, to meet this need, attention of many researchers and top network vendors has been directed towards millimeter wave radio links....... Operation in the millimeter wave range brings new possibilities for a channel allocation as well as allows wider radio channels to be used. Moreover this frequency range is lighter licensed than regular GSM. This clearly shows a huge potential of millimeter waves for a high speed wireless data transmission...... was proposed and research projects like IPHOBAC-NG were founded. The aim of the mentioned project is to employ novel RAUs featuring opticto-wireless and wireless-to-optic conversion with a speeds of 1-10Gbit/s for broadband wireless access and up to 3Gbit/s for mobile backhaul. The RAU proposed in this paper...

Bluetooth low energy: wireless connectivity for medical monitoring.

Science.gov (United States)

Omre, Alf Helge

2010-03-01

Electronic wireless sensors could cut medical costs by enabling physicians to remotely monitor vital signs such as blood pressure, blood glucose, and blood oxygenation while patients remain at home. According to the IDC report "Worldwide Bluetooth Semiconductor 2008-2012 Forecast," published November 2008, a forthcoming radio frequency communication ("wireless connectivity") standard, Bluetooth low energy, will link wireless sensors via radio signals to the 70% of cell phones and computers likely to be fitted with the next generation of Bluetooth wireless technology, leveraging a ready-built infrastructure for data transmission. Analysis of trends indicated by this data can help physicians better manage diseases such as diabetes. The technology also addresses the concerns of cost, compatibility, and interoperability that have previously stalled widespread adoption of wireless technology in medical applications. (c) 2010 Diabetes Technology Society.

LinkMind: link optimization in swarming mobile sensor networks.

Science.gov (United States)

Ngo, Trung Dung

2011-01-01

A swarming mobile sensor network is comprised of a swarm of wirelessly connected mobile robots equipped with various sensors. Such a network can be applied in an uncertain environment for services such as cooperative navigation and exploration, object identification and information gathering. One of the most advantageous properties of the swarming wireless sensor network is that mobile nodes can work cooperatively to organize an ad-hoc network and optimize the network link capacity to maximize the transmission of gathered data from a source to a target. This paper describes a new method of link optimization of swarming mobile sensor networks. The new method is based on combination of the artificial potential force guaranteeing connectivities of the mobile sensor nodes and the max-flow min-cut theorem of graph theory ensuring optimization of the network link capacity. The developed algorithm is demonstrated and evaluated in simulation.

LinkMind: Link Optimization in Swarming Mobile Sensor Networks

Directory of Open Access Journals (Sweden)

Trung Dung Ngo

2011-08-01

Full Text Available A swarming mobile sensor network is comprised of a swarm of wirelessly connected mobile robots equipped with various sensors. Such a network can be applied in an uncertain environment for services such as cooperative navigation and exploration, object identification and information gathering. One of the most advantageous properties of the swarming wireless sensor network is that mobile nodes can work cooperatively to organize an ad-hoc network and optimize the network link capacity to maximize the transmission of gathered data from a source to a target. This paper describes a new method of link optimization of swarming mobile sensor networks. The new method is based on combination of the artificial potential force guaranteeing connectivities of the mobile sensor nodes and the max-flow min-cut theorem of graph theory ensuring optimization of the network link capacity. The developed algorithm is demonstrated and evaluated in simulation.

Heterogeneous wireless/wireline optical access networks with the R-EAT as backend component

Science.gov (United States)

Hagedorn, Klaus; Gindera, Ralf; Stohr, Andreas; Jager, Dieter

2004-09-01

A heterogeneous wireless/wireline optical transmission link using a reflection type electroabsorption transceiver (R-EAT) is presented. Simultaneous transmission of full-duplex broadband wireless LAN (WLAN) channels and 1Gb/s base band data is experimentally demonstrated. The system link employs sub-carrier multiplexing (SCM) and two optical channels for full duplex transmission of various analog WLAN channels and downlink digital base band data. The developed link architecture is suitable for simultaneous transmission of broadband wireline and wireless signals, it enables the coexistence and interoperability between wireline and wireless access technologies. The developed R-EAT component employed in this wireline/wireless access system, features "single-chip-component" base stations in access networks with star type topology where only a single optical fiber is used for bidirectional optical transmission. The R-EAT can be used within the optical C-band (1530- 1560nm) and is suitable for (D)WDM networks. Bit error rate measurements demonstrate the capabilities of the R-EAT for 1Gb/s base band transmission. The analog performance for WLAN transmission is characterised by a spurious free dynamic range (SFDR) of more than 75dB and 90dB for uplink and downlink transmission, respectively. The link gain for uplink and downlink transmission is -42dB and -37dB, respectively. The demonstrates the analog performances of the R-EAT for being used in wireless access networks such as W-LAN.

Joint Impact of Frequency Synchronization Errors and Intermodulation Distortion on the Performance of Multicarrier DS-CDMA Systems

Directory of Open Access Journals (Sweden)

Rugini Luca

2005-01-01

Full Text Available The performance of multicarrier systems is highly impaired by intercarrier interference (ICI due to frequency synchronization errors at the receiver and by intermodulation distortion (IMD introduced by a nonlinear amplifier (NLA at the transmitter. In this paper, we evaluate the bit-error rate (BER of multicarrier direct-sequence code-division multiple-access (MC-DS-CDMA downlink systems subject to these impairments in frequency-selective Rayleigh fading channels, assuming quadrature amplitude modulation (QAM. The analytical findings allow to establish the sensitivity of MC-DS-CDMA systems to carrier frequency offset (CFO and NLA distortions, to identify the maximum CFO that is tolerable at the receiver side in different scenarios, and to find out the optimum value of the NLA output power backoff for a given CFO. Simulation results show that the approximated analysis is quite accurate in several conditions.

Wireless Emergency Alerts Commercial Mobile Service Provider (CMSP) Cybersecurity Guidelines

Science.gov (United States)

2016-06-16

Switching Centers (MSCs) in CDMA networks . The interface standard be- tween the MC and CDMA networks is the IS-824, IS-637 SMDPP.  Global System for... networks is 3GPP 23.041 CBS-BSC.  Universal Mobile Telecommunications System (UMTS) networks : A CBC function is collocated with a CMSP Gateway for message...agement 16. Does the carrier patch all systems and network devices as appropriate?    CMU/SEI-2016-SR-009 | SOFTWARE ENGINEERING INSTITUTE

Fundamental Analysis of Extremely Fast Photonic THz Wireless Communication Systems

DEFF Research Database (Denmark)

Yu, Xianbin; Zhang, Xianmin

This talk will review the recent progress on developing THz communication systems for high speed wireless access, and fundamentally analyze the realistic throughput and accessible wireless range of a THz impulse radio communication link by employing a uni-travelling photodiode (UTC-PD) as emitter...

Wireless neural recording with single low-power integrated circuit.

Science.gov (United States)

Harrison, Reid R; Kier, Ryan J; Chestek, Cynthia A; Gilja, Vikash; Nuyujukian, Paul; Ryu, Stephen; Greger, Bradley; Solzbacher, Florian; Shenoy, Krishna V

2009-08-01

We present benchtop and in vivo experimental results from an integrated circuit designed for wireless implantable neural recording applications. The chip, which was fabricated in a commercially available 0.6- mum 2P3M BiCMOS process, contains 100 amplifiers, a 10-bit analog-to-digital converter (ADC), 100 threshold-based spike detectors, and a 902-928 MHz frequency-shift-keying (FSK) transmitter. Neural signals from a selected amplifier are sampled by the ADC at 15.7 kSps and telemetered over the FSK wireless data link. Power, clock, and command signals are sent to the chip wirelessly over a 2.765-MHz inductive (coil-to-coil) link. The chip is capable of operating with only two off-chip components: a power/command receiving coil and a 100-nF capacitor.

VT Wireless Internet Service Providers 2006

Data.gov (United States)

Vermont Center for Geographic Information — (Link to Metadata) The VT Wireless Internet Service Provider (ISP) dataset (WISP2006) includes polygons depicting the extent of Vermont's WISP broadband system as of...

VT Wireless Internet Service Providers 2007

Data.gov (United States)

Vermont Center for Geographic Information — (Link to Metadata) The VT Wireless Internet Service Provider (ISP) dataset (WISP2007) includes polygons depicting the extent of Vermont's WISP broadband system as of...

Optical wireless communications for micromachines

Science.gov (United States)

O'Brien, Dominic C.; Yuan, Wei Wen; Liu, Jing Jing; Faulkner, Grahame E.; Elston, Steve J.; Collins, Steve; Parry-Jones, Lesley A.

2006-08-01

A key challenge for wireless sensor networks is minimizing the energy required for network nodes to communicate with each other, and this becomes acute for self-powered devices such as 'smart dust'. Optical communications is a potentially attractive solution for such devices. The University of Oxford is currently involved in a project to build optical wireless links to smart dust. Retro-reflectors combined with liquid crystal modulators can be integrated with the micro-machine to create a low power transceiver. When illuminated from a base station a modulated beam is returned, transmitting data. Data from the base station can be transmitted using modulation of the illuminating beam and a receiver at the micro-machine. In this paper we outline the energy consumption and link budget considerations in the design of such micro-machines, and report preliminary experimental results.

Propagation Engineering in Wireless Communications

CERN Document Server

Ghasemi, Abdollah; Ghasemi, Farshid

2012-01-01

Wireless communications has seen explosive growth in recent decades, in a realm that is both broad and rapidly expanding to include satellite services, navigational aids, remote sensing, telemetering, audio and video broadcasting, high-speed data communications, mobile radio systems and much more. Propagation Engineering in Wireless Communications deals with the basic principles of radiowaves propagation for frequency bands used in radio-communications, offering descriptions of new achievements and newly developed propagation models. The book bridges the gap between theoretical calculations and approaches, and applied procedures needed for advanced radio links design. The primary objective of this two-volume set is to demonstrate the fundamentals, and to introduce propagation phenomena and mechanisms that engineers are likely to encounter in the design and evaluation of radio links of a given type and operating frequency. Volume one covers basic principles, along with tropospheric and ionospheric propagation,...

Combined Effect of Random Transmit Power Control and Inter-Path Interference Cancellation on DS-CDMA Packet Mobile Communications

Science.gov (United States)

Kudoh, Eisuke; Ito, Haruki; Wang, Zhisen; Adachi, Fumiyuki

In mobile communication systems, high speed packet data services are demanded. In the high speed data transmission, throughput degrades severely due to severe inter-path interference (IPI). Recently, we proposed a random transmit power control (TPC) to increase the uplink throughput of DS-CDMA packet mobile communications. In this paper, we apply IPI cancellation in addition to the random TPC. We derive the numerical expression of the received signal-to-interference plus noise power ratio (SINR) and introduce IPI cancellation factor. We also derive the numerical expression of system throughput when IPI is cancelled ideally to compare with the Monte Carlo numerically evaluated system throughput. Then we evaluate, by Monte-Carlo numerical computation method, the combined effect of random TPC and IPI cancellation on the uplink throughput of DS-CDMA packet mobile communications.

Virtual Lab for Wireless Sensor Networks

Directory of Open Access Journals (Sweden)

PICOVICI, D.

2008-06-01

Full Text Available This article details an experimental system developed to enhance the education and research in the area of wireless networks technologies. The system referred, as Virtual Lab (VL is primarily targeting first time users or users with limited experience in programming and using wireless sensor networks. The VL enables a set of predefined sensor networks to be remotely accessible and controlled for constructive and time-efficient experimentation. In order to facilitate the user's wireless sensor applications, the VL is using three main components: a a Virtual Lab Motes (VLM, representing the wireless sensor, b a Virtual Lab Client (VLC, representing the user's tool to interact with the VLM and c a Virtual Lab Server (VLS representing the software link between the VLM and VLC. The concept has been proven using the moteiv produced Tmote Sky modules. Initial experimental use clearly demonstrates that the VL approach reduces dramatically the learning curve involved in programming and using the associated wireless sensor nodes. In addition the VL allows the user's focus to be directed towards the experiment and not towards the software programming challenges.

OPTICAL WIRELESS COMMUNICATION SYSTEM

Directory of Open Access Journals (Sweden)

JOSHUA L.Y. CHIENG

2016-02-01

Full Text Available The growing demand of bandwidth in this modern internet age has been testing the existing telecommunication infrastructures around the world. With broadband speeds moving towards the region of Gbps and Tbps, many researches have begun on the development of using optical wireless technology as feasible and future methods to the current wireless technology. Unlike the existing radio frequency wireless applications, optical wireless uses electromagnetic spectrums that are unlicensed and free. With that, this project aim to understand and gain better understanding of optical wireless communication system by building an experimental and simulated model. The quality of service and system performance will be investigated and reviewed. This project employs laser diode as the propagation medium and successfully transferred audio signals as far as 15 meters. On its quality of service, results of the project model reveal that the bit error rate increases, signal-to-noise ratio and quality factor decreases as the link distance between the transmitter and receiver increases. OptiSystem was used to build the simulated model and MATLAB was used to assist signal-to-noise ratio calculations. By comparing the simulated and experimental receiver’s power output, the experimental model’s efficiency is at 66.3%. Other than the system’s performance, challenges and factors affecting the system have been investigated and discussed. Such challenges include beam divergence, misalignment and particle absorption.

Channel characterization for high-speed W-band wireless communication links

DEFF Research Database (Denmark)

Rommel, Simon; Cavalcante, Lucas Costa Pereira; Vegas Olmos, Juan José

2015-01-01

We present and discuss results from an experimental characterization of the W-band indoor wireless channel, including both large and small scale fading phenomena as well as corresponding channel parameters and their impact on system performance....

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.

A practical monitoring system for the structural safety of mega-trusses using wireless vibrating wire strain gauges.

Science.gov (United States)

Park, Hyo Seon; Lee, Hwan Young; Choi, Se Woon; Kim, Yousok

2013-12-16

Sensor technologies have been actively employed in structural health monitoring (SHM) to evaluate structural safety. To provide stable and real-time monitoring, a practical wireless sensor network system (WSNS) based on vibrating wire strain gauges (VWSGs) is proposed and applied to a building under construction. In this WSNS, the data measured from each VWSG are transmitted to the sensor node via a signal line and then transmitted to the master node through a short-range wireless communication module (operating on the Industrial, Scientific, and Medical (ISM) band). The master node also employs a long-range wireless communication module (Code Division Multiple Access-CDMA) to transmit the received data from the sensor node to a server located in a remote area, which enables a manager to examine the measured data in real time without any time or location restrictions. In this study, a total of 48 VWSGs, 14 sensor nodes, and seven master nodes were implemented to measure long-term strain variations of mega-trusses in an irregular large-scale building under construction. Based on strain data collected over a 16-month period, a quantitative evaluation of the construction process was performed to determine the aspects that exhibit the greatest influence on member behavior and to conduct a comparison with numerical simulation results. The effect of temperature stress on the structural elements was also analyzed. From these observations, the feasibility of a long-term WSNS based on VWSGs to evaluate the structural safety of an irregular building under construction was confirmed.

A Practical Monitoring System for the Structural Safety of Mega-Trusses Using Wireless Vibrating Wire Strain Gauges

Directory of Open Access Journals (Sweden)

Hyo Seon Park

2013-12-01

Full Text Available Sensor technologies have been actively employed in structural health monitoring (SHM to evaluate structural safety. To provide stable and real-time monitoring, a practical wireless sensor network system (WSNS based on vibrating wire strain gauges (VWSGs is proposed and applied to a building under construction. In this WSNS, the data measured from each VWSG are transmitted to the sensor node via a signal line and then transmitted to the master node through a short-range wireless communication module (operating on the Industrial, Scientific, and Medical (ISM band. The master node also employs a long-range wireless communication module (Code Division Multiple Access—CDMA to transmit the received data from the sensor node to a server located in a remote area, which enables a manager to examine the measured data in real time without any time or location restrictions. In this study, a total of 48 VWSGs, 14 sensor nodes, and seven master nodes were implemented to measure long-term strain variations of mega-trusses in an irregular large-scale building under construction. Based on strain data collected over a 16-month period, a quantitative evaluation of the construction process was performed to determine the aspects that exhibit the greatest influence on member behavior and to conduct a comparison with numerical simulation results. The effect of temperature stress on the structural elements was also analyzed. From these observations, the feasibility of a long-term WSNS based on VWSGs to evaluate the structural safety of an irregular building under construction was confirmed.

Radio-frequency transparent demodulation for broadband hybrid wireless-optical links

DEFF Research Database (Denmark)

Zibar, Darko; Sambaraju, Rakesh; Alemany, Ruben

2010-01-01

A novel demodulation technique which is transparent to radio-frequency (RF) carrier frequency is presented and experimentally demonstrated for multigigabit wireless signals. The presented demodulation technique employs optical single-sideband filtering, coherent detection, and baseband digital si...

Wireless Mobile Computing and its Links to Descriptive Complexity

Czech Academy of Sciences Publication Activity Database

Wiedermann, Jiří; Pardubská, D.

2008-01-01

Roč. 19, č. 4 (2008), s. 887-913 ISSN 0129-0541 R&D Projects: GA AV ČR 1ET100300517 Institutional research plan: CEZ:AV0Z10300504 Keywords : alternating Turing machine * simulation * simultaneous time-space complexity * wireless parallel Turing machine Subject RIV: IN - Informatics, Computer Science Impact factor: 0.554, year: 2008

Wireless Neural Recording With Single Low-Power Integrated Circuit

Science.gov (United States)

Harrison, Reid R.; Kier, Ryan J.; Chestek, Cynthia A.; Gilja, Vikash; Nuyujukian, Paul; Ryu, Stephen; Greger, Bradley; Solzbacher, Florian; Shenoy, Krishna V.

2010-01-01

We present benchtop and in vivo experimental results from an integrated circuit designed for wireless implantable neural recording applications. The chip, which was fabricated in a commercially available 0.6-μm 2P3M BiCMOS process, contains 100 amplifiers, a 10-bit analog-to-digital converter (ADC), 100 threshold-based spike detectors, and a 902–928 MHz frequency-shift-keying (FSK) transmitter. Neural signals from a selected amplifier are sampled by the ADC at 15.7 kSps and telemetered over the FSK wireless data link. Power, clock, and command signals are sent to the chip wirelessly over a 2.765-MHz inductive (coil-to-coil) link. The chip is capable of operating with only two off-chip components: a power/command receiving coil and a 100-nF capacitor. PMID:19497825

GENERALIZED PROCESSOR SHARING (GPS) TECHNIQUES

African Journals Online (AJOL)

Olumide

services (QoS) is usually difficult especially with static network resources. A flexible and ... NIGERIAN JOURNAL OF TECHNOLOGY, VOL. 29 NO.1 ..... Wideband CDMA Cellular. Networks, IEEE Trans. Wireless. Commun., Vol. 3, Number 1 ...

HOT SPOT RELIEF WITH EMBEDDED BEAM FOR CDMA SYSTEMS IN HAPS

Institute of Scientific and Technical Information of China (English)

无

2006-01-01

This paper proposes a novel micro/macro beam coverage scheme used in High Altitude Platform System (HAPS) Code Division Multiple Access (CDMA) systems. A relief of traffic burden in hot spot areas is achieved by embedding micro-beams into the macro-beams at the hot spot locations, together with appropriate power ratio control and user ratio control. The simulation results show that the hot spot problem can be relieved efficiently with the presented configuration, and a higher and more stable system capacity is expectable despite the variation of user distribution.

A CDMA multiuser detection algorithm on the basis of belief propagation

International Nuclear Information System (INIS)

Kabashima, Yoshiyuki

2003-01-01

An iterative algorithm for the multiuser detection problem that arises in code division multiple access (CDMA) systems is developed on the basis of Pearl's belief propagation (BP). We show that the BP-based algorithm exhibits nearly optimal performance in a practical time scale by utilizing the central limit theorem and self-averaging property appropriately, whereas direct application of BP to the detection problem is computationally difficult and far from practical. We further present close relationships of the proposed algorithm to the Thouless-Anderson-Palmer approach and replica analysis known in spin-glass research

Radio over fiber for wireless communications from fundamentals to advanced topics

CERN Document Server

Fernando, Xavier N

2014-01-01

A comprehensive evaluation of Fi-Wi,  enabling readers to design links using channel estimation and equalization algorithms  This book provides a detailed study of radio over fiber (ROF) based wireless communication systems, otherwise called fiber wireless (Fi-Wi) systems. This is an emerging hot topic where the abundant bandwidth of optical fiber is directly combined with the flexibility and mobility of wireless networks to provide broadband connectivity.  Its application is increasing because of the growing demand for broadband wireless services. In such a system the transmission of the ra

How to model wireless mesh networks topology

International Nuclear Information System (INIS)

Sanni, M L; Hashim, A A; Anwar, F; Ali, S; Ahmed, G S M

2013-01-01

The specification of network connectivity model or topology is the beginning of design and analysis in Computer Network researches. Wireless Mesh Networks is an autonomic network that is dynamically self-organised, self-configured while the mesh nodes establish automatic connectivity with the adjacent nodes in the relay network of wireless backbone routers. Researches in Wireless Mesh Networks range from node deployment to internetworking issues with sensor, Internet and cellular networks. These researches require modelling of relationships and interactions among nodes including technical characteristics of the links while satisfying the architectural requirements of the physical network. However, the existing topology generators model geographic topologies which constitute different architectures, thus may not be suitable in Wireless Mesh Networks scenarios. The existing methods of topology generation are explored, analysed and parameters for their characterisation are identified. Furthermore, an algorithm for the design of Wireless Mesh Networks topology based on square grid model is proposed in this paper. The performance of the topology generated is also evaluated. This research is particularly important in the generation of a close-to-real topology for ensuring relevance of design to the intended network and validity of results obtained in Wireless Mesh Networks researches

Design of power controller in CDMA system with power and SIR error minimization

Institute of Scientific and Technical Information of China (English)

Shulan KONG; Huanshui ZHANG; Zhaosheng ZHANG; Hongxia WANG

2007-01-01

In this paper, an uplink power control problem is considered for code division multiple access (CDMA) systems. A distributed algorithm is proposed based on linear quadratic optimal control theory. The proposed scheme minimizes the sum of the power and the error of signal-to-interference ratio (SIR). A power controller is designed by constructing an optimization problem of a stochastic linear quadratic type in Krein space and solving a Kalman filter problem.

Design and implementation of a topology control scheme for wireless mesh networks

CSIR Research Space (South Africa)

Mudali, P

2009-09-01

Full Text Available The Wireless Mesh Network (WMN) backbone is usually comprised of stationary nodes but the transient nature of wireless links results in changing network topologies. Topology Control (TC) aims to preserve network connectivity in ad hoc and mesh...

Perbandingan Perhitungan Trafik Jam Sibuk CDMA 2000 1x pada BTS Inner City dan BTS Outer City dengan Mempergunakan Metode ADPH, TCBH, FDMH dan FDMP

Directory of Open Access Journals (Sweden)

Eka Wahyudi

2013-11-01

Full Text Available Cellular communication system is a wireless communication system where the subscriber can move within a wide network coverage. Code Division Multiple Access (CDMA is a multiuser access technology that is each user uses a unique code contained in the access channel in the system. Calculation and determination of peak hours can be done by several methods such as: Average Daily Peak Hour (ADPH, Time Consistent Busy Hour (TCBH, Fixed Daily Measurement Hour (FDMH, Fixed Daily Measurement Period (FDMP. The effectiveness of the channel should be determined by occupancy both at inner city territory and outer city  territory location. Using design Erlang (Erl for supply channel at Base Transceiver Station (BTS that provided, BTS has a design Erlang of 369,83 Erl at inner city and it has a design Erlang of 241,8 Erl at outer city. Peak hour on the inner city occurred at 12:00 to 15:00, whereas the outer city of peak hour occurred at 18:00 to 21:00. Effectiveness value that determined by operator are : 70% = high occupancy (very effective. In this case occupancy values obtained in each method is between 21% to 69% which means effective

Wireless technologies for closed-loop retinal prostheses

Science.gov (United States)

Ng, David C.; Bai, Shun; Yang, Jiawei; Tran, Nhan; Skafidas, Efstratios

2009-12-01

In this paper, we discuss various technologies needed to develop retinal prostheses with wireless power and data telemetry operation. In addition to the need to communicate with the implanted device, supply of power to the retinal prosthesis is especially difficult. This is because, in the implanted state, the device is not fixed in position due to constant motion of the eye. Furthermore, a retinal prosthesis incorporating a high density electrode array of more than 1000 electrodes is expected to consume approximately 45 mW of power and require 300 kbps of image and stimulation data. The front end of the wireless power and data transmission, the antenna, needs to be small compared to the size of the eye. Also, the wireless module is expected to operate in the reactive near-field region due to small separation between the transmit and receive antennas compared to their size and corresponding operating wavelength. An inductive link is studied as a means to transfer power and for data telemetry between the implant and external unit. In this work, the use of integrated circuit and microfabrication technologies for implementing inductive links is discussed. A closed-loop approach is taken to improve performance and reach optimum operation condition. Design and simulation data are presented as the basis for development of viable wireless module prototypes.

Impact of wireless communication on multimedia application performance

Science.gov (United States)

Brown, Kevin A.

1999-01-01

Multimedia applications and specifically voice and video conferencing tools are widely used in business communications, and are quickly being discovered by the consumer market as well. At the same time, wireless communication services such as PCS voice and cellular data are becoming very popular, leading to the desire to deploy multimedia applications in the wireless environment. Wireless links, however, exhibit several characteristics which are different from traditional wired networks. These include: dynamically changing bandwidth due to mobile host movement in and out of cell where bandwidth is shared, high rates of packet corruption and subsequent loss, and frequent are lengthy disconnections due to obstacles, fading, and movement between cells. In addition, these effects are short-lived and difficult to reproduce, leading to a lack of adequate testing and analysis for applications used in wireless environments.

Network Coding Opportunities for Wireless Grids Formed by Mobile Devices

DEFF Research Database (Denmark)

Nielsen, Karsten Fyhn; Madsen, Tatiana Kozlova; Fitzek, Frank

2008-01-01

Wireless grids have potential in sharing communication, computational and storage resources making these networks more powerful, more robust, and less cost intensive. However, to enjoy the benefits of cooperative resource sharing, a number of issues should be addressed and the cost of the wireless...... link should be taken into account. We focus on the question how nodes can efficiently communicate and distribute data in a wireless grid. We show the potential of a network coding approach when nodes have the possibility to combine packets thus increasing the amount of information per transmission. Our...... implementation demonstrates the feasibility of network coding for wireless grids formed by mobile devices....

Selective Adaptive Parallel Interference Cancellation for Multicarrier DS-CDMA Systems

Directory of Open Access Journals (Sweden)

Ahmed El-Sayed El-Mahdy

2013-07-01

Full Text Available In this paper, Selective Adaptive Parallel Interference Cancellation (SA-PIC technique is presented for Multicarrier Direct Sequence Code Division Multiple Access (MC DS-CDMA scheme. The motivation of using SA-PIC is that it gives high performance and at the same time, reduces the computational complexity required to perform interference cancellation. An upper bound expression of the bit error rate (BER for the SA-PIC under Rayleigh fading channel condition is derived. Moreover, the implementation complexities for SA-PIC and Adaptive Parallel Interference Cancellation (APIC are discussed and compared. The performance of SA-PIC is investigated analytically and validated via computer simulations.

Voice over IP in Wireless Heterogeneous Networks

DEFF Research Database (Denmark)

Fathi, Hanane; Chakraborty, Shyam; Prasad, Ramjee

with the deployment of wireless heterogeneous systems, both speech and data traffic are carrried over wireless links by the same IP-based packet-switched infrastructure. However, this combination faces some challenges due to the inherent properties of the wireless network. The requirements for good quality VoIP...... communications are difficult to achieve in a time-varying environment due to channel errors and traffic congestion and across different systems. The provision of VoIP in wireless heterogeneous networks requires a set of time-efficient control mechanisms to support a VoIP session with acceptable quality....... The focus of Voice over IP in Wierless Heterogeneous Networks is on mechanisms that affect the VoIP user satisfaction  while not explicitly involved in the media session. This relates to the extra delays introduced by the security and the signaling protocols used to set up an authorized VoIP session...

Adaptive Cross-Layer Distributed Energy-Efficient Resource Allocation Algorithms for Wireless Data Networks

Directory of Open Access Journals (Sweden)

Daniela Saturnino

2008-10-01

Full Text Available The issue of adaptive and distributed cross-layer resource allocation for energy efficiency in uplink code-division multiple-access (CDMA wireless data networks is addressed. The resource allocation problems are formulated as noncooperative games wherein each terminal seeks to maximize its own energy efficiency, namely, the number of reliably transmitted information symbols per unit of energy used for transmission. The focus of this paper is on the issue of adaptive and distributed implementation of policies arising from this approach, that is, it is assumed that only readily available measurements, such as the received data, are available at the receiver in order to play the considered games. Both single-cell and multicell networks are considered. Stochastic implementations of noncooperative games for power allocation, spreading code allocation, and choice of the uplink (linear receiver are thus proposed, and analytical results describing the convergence properties of selected stochastic algorithms are also given. Extensive simulation results show that, in many instances of practical interest, the proposed stochastic algorithms approach with satisfactory accuracy the performance of nonadaptive games, whose implementation requires much more prior information.

Power Control and Coding Formulation for State Estimation with Wireless Sensors

DEFF Research Database (Denmark)

Quevedo, Daniel; Østergaard, Jan; Ahlen, Anders

2014-01-01

efficient communication. In this paper, we examine the role of power control and coding for Kalman filtering over wireless correlated channels. Two estimation architectures are considered; initially, the sensors send their measurements directly to a single gateway (GW). Next, wireless relay nodes provide...... additional links. The GW decides on the coding scheme and the transmitter power levels of the wireless nodes. The decision process is carried out online and adapts to varying channel conditions to improve the tradeoff between state estimation accuracy and energy expenditure. In combination with predictive......Technological advances made wireless sensors cheap and reliable enough to be brought into industrial use. A major challenge arises from the fact that wireless channels introduce random packet dropouts. Power control and coding are key enabling technologies in wireless communications to ensure...

THz photonic wireless links with 16-QAM modulation in the 375-450 GHz band

DEFF Research Database (Denmark)

Jia, Shi; Yu, Xianbin; Hu, Hao

2016-01-01

forward error correction (HD-FEC) threshold of 3.8e-3 with 7% overhead. In addition, we also successfully demonstrate hybrid photonic wireless transmission of 40 Gbit/s 16-QAM signal at carrier frequencies of 400 GHz and 425 GHz over 30 km standard single mode fiber (SSMF) between the optical baseband...... signal transmitter and the THz wireless transmitter with negligible induced power penalty.......We propose and experimentally demonstrate THz photonic wireless communication systems with 16-QAM modulation in the 375-450 GHz band. The overall throughput reaches as high as 80 Gbit/s by exploiting four THz channels with 5 Gbaud 16-QAM baseband modulation per channel. We create a coherent optical...

Analysis of route availability in inter-working multi-hop wireless networks

CSIR Research Space (South Africa)

Salami, O

2009-07-01

Full Text Available In order to link a source-destination node pair in inter-working multi-hop wireless networks, links or routes must first be available. It is only after establishing the availability of links and routes between nodes that factors which affect...

Supporting Adaptation of Wireless Communication Protocols

International Nuclear Information System (INIS)

Dhomeja, L.D.; Soomro, I.A.; Malkani, Y.A.

2016-01-01

Pervasive devices such as mobile phones and PDAs (Personal Digital Assistants) come with different wireless communication capabilities, for example, WiFi (Wireless Fidelity), Bluetooth, IrDA (Infrared), etc. In order for pervasive devices to interact with each other, they need to have matching (alike) communication capabilities, otherwise such heterogeneous devices would not be able to interact with each other. In this paper we address this issue and propose a system that makes devices with heterogeneous wireless communication capabilities communicate with each other. The proposed system supports adaptation of wireless communication protocols through a proxy, which sits between a client and a server, and supports adaptation of wireless communication protocols. Its functionality involves intercepting a request made by a client with a different wireless communication capability (e.g. Bluetooth) from what the server has (e.g. WiFi), connecting to the server and then sending results back to the client. We have tested the system by implementing a messaging service application and running it on the system. The proxy supports all Bluetooth protocols, i.e. OBEX (Object Exchange), L2CAP (Logical Link Control and Adaptation Protocol), RFCOM (Radio Frequency Communication) and WiFi protocol and can run on (J2MW (Java 2 Micro Edition) enabled mobile phones which support both Bluetooth and WiFi capabilities. (author)

Design and Evaluation of 10-Gbps Inter-satellite Optical Wireless Communication Link for Improved Performance

Science.gov (United States)

Gupta, Amit; Nagpal, Shaina

2017-05-01

Inter-satellite optical wireless communication (IsOWC) systems can be chosen over existing microwave satellite systems for deploying in space in the future due to their high bandwidth, small size, light weight, low power and low cost. However, the IsOWC system suffers from various attenuations due to weather conditions, turbulence or scintillations which limit its performance and decreases its availability. So, in order to improve the performance, IsOWC system using directly modulated laser source is proposed in this work. The system is designed and evaluated to be suitable for high data rate transmissions up to 10 Gbps. The performance of the system is investigated in order to reduce the cost and complexity of link and improving the quality of information signal. Further the proposed IsOWC system is analysed using BER analyser, power meter and oscilloscope Visualizer.

A Joint Optimization Criterion for Blind DS-CDMA Detection

Directory of Open Access Journals (Sweden)

Sergio A. Cruces-Alvarez

2007-01-01

Full Text Available This paper addresses the problem of the blind detection of a desired user in an asynchronous DS-CDMA communications system with multipath propagation channels. Starting from the inverse filter criterion introduced by Tugnait and Li in 2001, we propose to tackle the problem in the context of the blind signal extraction methods for ICA. In order to improve the performance of the detector, we present a criterion based on the joint optimization of several higher-order statistics of the outputs. An algorithm that optimizes the proposed criterion is described, and its improved performance and robustness with respect to the near-far problem are corroborated through simulations. Additionally, a simulation using measurements on a real software-radio platform at 5 GHz has also been performed.

A Joint Optimization Criterion for Blind DS-CDMA Detection

Science.gov (United States)

Durán-Díaz, Iván; Cruces-Alvarez, Sergio A.

2006-12-01

This paper addresses the problem of the blind detection of a desired user in an asynchronous DS-CDMA communications system with multipath propagation channels. Starting from the inverse filter criterion introduced by Tugnait and Li in 2001, we propose to tackle the problem in the context of the blind signal extraction methods for ICA. In order to improve the performance of the detector, we present a criterion based on the joint optimization of several higher-order statistics of the outputs. An algorithm that optimizes the proposed criterion is described, and its improved performance and robustness with respect to the near-far problem are corroborated through simulations. Additionally, a simulation using measurements on a real software-radio platform at 5 GHz has also been performed.

Redes celulares de tercera generación: CDMA2000 Y WCDMA

OpenAIRE

Jaime Sánchez García; Myriam Meza Múgica

2005-01-01

Este artículo ofrece un panorama general de los sistemas de comunicaciones móviles celulares de tercera generación (3G) que han tenido una mayor aceptación (CDMA2000 y WCDMA) en el mercado, y una comparación basada en los puntos principales donde los sistemas difieren que indica las ventajas y desventajas de cada uno. Los sistemas de comunicaciones móviles celulares 3G ofrecen mayores capacidades de transmisión a los de segunda generación (2G), y permiten brindar, además de los tr...

Improving performance of DS-CDMA systems using chaotic complex Bernoulli spreading codes

Science.gov (United States)

Farzan Sabahi, Mohammad; Dehghanfard, Ali

2014-12-01

The most important goal of spreading spectrum communication system is to protect communication signals against interference and exploitation of information by unintended listeners. In fact, low probability of detection and low probability of intercept are two important parameters to increase the performance of the system. In Direct Sequence Code Division Multiple Access (DS-CDMA) systems, these properties are achieved by multiplying the data information in spreading sequences. Chaotic sequences, with their particular properties, have numerous applications in constructing spreading codes. Using one-dimensional Bernoulli chaotic sequence as spreading code is proposed in literature previously. The main feature of this sequence is its negative auto-correlation at lag of 1, which with proper design, leads to increase in efficiency of the communication system based on these codes. On the other hand, employing the complex chaotic sequences as spreading sequence also has been discussed in several papers. In this paper, use of two-dimensional Bernoulli chaotic sequences is proposed as spreading codes. The performance of a multi-user synchronous and asynchronous DS-CDMA system will be evaluated by applying these sequences under Additive White Gaussian Noise (AWGN) and fading channel. Simulation results indicate improvement of the performance in comparison with conventional spreading codes like Gold codes as well as similar complex chaotic spreading sequences. Similar to one-dimensional Bernoulli chaotic sequences, the proposed sequences also have negative auto-correlation. Besides, construction of complex sequences with lower average cross-correlation is possible with the proposed method.

Subband Adaptive Array for DS-CDMA Mobile Radio

Directory of Open Access Journals (Sweden)

Tran Xuan Nam

2004-01-01

Full Text Available We propose a novel scheme of subband adaptive array (SBAA for direct-sequence code division multiple access (DS-CDMA. The scheme exploits the spreading code and pilot signal as the reference signal to estimate the propagation channel. Moreover, instead of combining the array outputs at each output tap using a synthesis filter and then despreading them, we despread directly the array outputs at each output tap by the desired user's code to save the synthesis filter. Although its configuration is far different from that of 2D RAKEs, the proposed scheme exhibits relatively equivalent performance of 2D RAKEs while having less computation load due to utilising adaptive signal processing in subbands. Simulation programs are carried out to explore the performance of the scheme and compare its performance with that of the standard 2D RAKE.

Analysis and Testing of Mobile Wireless Networks

Science.gov (United States)

Alena, Richard; Evenson, Darin; Rundquist, Victor; Clancy, Daniel (Technical Monitor)

2002-01-01

Wireless networks are being used to connect mobile computing elements in more applications as the technology matures. There are now many products (such as 802.11 and 802.11b) which ran in the ISM frequency band and comply with wireless network standards. They are being used increasingly to link mobile Intranet into Wired networks. Standard methods of analyzing and testing their performance and compatibility are needed to determine the limits of the technology. This paper presents analytical and experimental methods of determining network throughput, range and coverage, and interference sources. Both radio frequency (BE) domain and network domain analysis have been applied to determine wireless network throughput and range in the outdoor environment- Comparison of field test data taken under optimal conditions, with performance predicted from RF analysis, yielded quantitative results applicable to future designs. Layering multiple wireless network- sooners can increase performance. Wireless network components can be set to different radio frequency-hopping sequences or spreading functions, allowing more than one sooner to coexist. Therefore, we ran multiple 802.11-compliant systems concurrently in the same geographical area to determine interference effects and scalability, The results can be used to design of more robust networks which have multiple layers of wireless data communication paths and provide increased throughput overall.

An Interference-Aware Traffic-Priority-Based Link Scheduling Algorithm for Interference Mitigation in Multiple Wireless Body Area Networks

Directory of Open Access Journals (Sweden)

Thien T. T. Le

2016-12-01

Full Text Available Currently, wireless body area networks (WBANs are effectively used for health monitoring services. However, in cases where WBANs are densely deployed, interference among WBANs can cause serious degradation of network performance and reliability. Inter-WBAN interference can be reduced by scheduling the communication links of interfering WBANs. In this paper, we propose an interference-aware traffic-priority-based link scheduling (ITLS algorithm to overcome inter-WBAN interference in densely deployed WBANs. First, we model a network with multiple WBANs as an interference graph where node-level interference and traffic priority are taken into account. Second, we formulate link scheduling for multiple WBANs as an optimization model where the objective is to maximize the throughput of the entire network while ensuring the traffic priority of sensor nodes. Finally, we propose the ITLS algorithm for multiple WBANs on the basis of the optimization model. High spatial reuse is also achieved in the proposed ITLS algorithm. The proposed ITLS achieves high spatial reuse while considering traffic priority, packet length, and the number of interfered sensor nodes. Our simulation results show that the proposed ITLS significantly increases spatial reuse and network throughput with lower delay by mitigating inter-WBAN interference.

Support vector machine multiuser receiver for DS-CDMA signals in multipath channels.

Science.gov (United States)

Chen, S; Samingan, A K; Hanzo, L

2001-01-01

The problem of constructing an adaptive multiuser detector (MUD) is considered for direct sequence code division multiple access (DS-CDMA) signals transmitted through multipath channels. The emerging learning technique, called support vector machines (SVM), is proposed as a method of obtaining a nonlinear MUD from a relatively small training data block. Computer simulation is used to study this SVM MUD, and the results show that it can closely match the performance of the optimal Bayesian one-shot detector. Comparisons with an adaptive radial basis function (RBF) MUD trained by an unsupervised clustering algorithm are discussed.

SIMO optical wireless links with nonzero boresight pointing errors over M modeled turbulence channels

Science.gov (United States)

Varotsos, G. K.; Nistazakis, H. E.; Petkovic, M. I.; Djordjevic, G. T.; Tombras, G. S.

2017-11-01

Over the last years terrestrial free-space optical (FSO) communication systems have demonstrated an increasing scientific and commercial interest in response to the growing demands for ultra high bandwidth, cost-effective and secure wireless data transmissions. However, due the signal propagation through the atmosphere, the performance of such links depends strongly on the atmospheric conditions such as weather phenomena and turbulence effect. Additionally, their operation is affected significantly by the pointing errors effect which is caused by the misalignment of the optical beam between the transmitter and the receiver. In order to address this significant performance degradation, several statistical models have been proposed, while particular attention has been also given to diversity methods. Here, the turbulence-induced fading of the received optical signal irradiance is studied through the M (alaga) distribution, which is an accurate model suitable for weak to strong turbulence conditions and unifies most of the well-known, previously emerged models. Thus, taking into account the atmospheric turbulence conditions along with the pointing errors effect with nonzero boresight and the modulation technique that is used, we derive mathematical expressions for the estimation of the average bit error rate performance for SIMO FSO links. Finally, proper numerical results are given to verify our derived expressions and Monte Carlo simulations are also provided to further validate the accuracy of the analysis proposed and the obtained mathematical expressions.

Photonics-assisted wireless link based on mm-wave reconfigurable antennas

DEFF Research Database (Denmark)

Feliciano daCosta, Igor; Cerqueira Sodré, Arismar; Rodriguez Páez, Juan Sebastián

2017-01-01

The authors report a novel concept for photonics-assisted and broadband optical-wireless indoor networks based on optically-controlled reconfigurable antenna arrays (OCRAAs) and photonic down conversion (PDC) techniques, operating in the 28 and 38 GHz frequency bands. The antenna bandwidth is opt...... for access networks in the mm-wave frequency range....

Battling Latency in Modern Wireless Networks

KAUST Repository

Showail, Ahmad

2018-05-15

Buffer sizing has a tremendous effect on the performance of Wi-Fi based networks. Choosing the right buffer size is challenging due to the dynamic nature of the wireless environment. Over buffering or ‘bufferbloat’ may produce unacceptable endto-end delays. On the other hand, small buffers may limit the performance gains that can be obtained with various IEEE 802.11n/ac enhancements, such as frame aggregation. We propose Wireless Queue Management (WQM), a novel, practical, and lightweight queue management scheme for wireless networks. WQM adapts the buffer size based on the wireless link characteristics and the network load. Furthermore, it accounts for aggregates length when deciding on the optimal buffer size. We evaluate WQM using our 10 nodes wireless testbed. WQM reduces the end-to-end delay by an order of magnitude compared to the default buffer size in Linux while achieving similar network throughput. Also, WQM outperforms state of the art bufferbloat solutions, namely CoDel and PIE. WQM achieves 7× less latency compared to PIE, and 2× compared to CoDel at the cost of 8% drop in goodput in the worst case. Further, WQM improves network fairness as it limits the ability of a single flow to saturate the buffers.

Battling Latency in Modern Wireless Networks

KAUST Repository

Showail, Ahmad; Shihada, Basem

2018-01-01

Buffer sizing has a tremendous effect on the performance of Wi-Fi based networks. Choosing the right buffer size is challenging due to the dynamic nature of the wireless environment. Over buffering or ‘bufferbloat’ may produce unacceptable endto-end delays. On the other hand, small buffers may limit the performance gains that can be obtained with various IEEE 802.11n/ac enhancements, such as frame aggregation. We propose Wireless Queue Management (WQM), a novel, practical, and lightweight queue management scheme for wireless networks. WQM adapts the buffer size based on the wireless link characteristics and the network load. Furthermore, it accounts for aggregates length when deciding on the optimal buffer size. We evaluate WQM using our 10 nodes wireless testbed. WQM reduces the end-to-end delay by an order of magnitude compared to the default buffer size in Linux while achieving similar network throughput. Also, WQM outperforms state of the art bufferbloat solutions, namely CoDel and PIE. WQM achieves 7× less latency compared to PIE, and 2× compared to CoDel at the cost of 8% drop in goodput in the worst case. Further, WQM improves network fairness as it limits the ability of a single flow to saturate the buffers.

BAMUD Features Demonstration by System View

Directory of Open Access Journals (Sweden)

D. Kocur

2004-09-01

Full Text Available Direct-sequence code-division multiple access (DS-CDMA is afrequently used wireless technology in DS-CDMA communications. Theconventional DS-CDMA detector follows a single-user detection strategyin which each user is detected separately without regard for the otherusers. The better strategy is multi-user detection (MUD, whereinformation about multiple users is used to improve detection of eachindividual user. This paper presents an adaptive multi-user detectorconverging (for any initialization to the minimum mean square error(MMSE detector without requiring training sequences. This blindmulti-user detector (BAMUD requires no more knowledge than does theconventional single-user detector. The structure of adaptive blinddetector is simulated by the system design tool SystemView. The aimfocus is to verify theoretical knowledge of BAMUD structure usinghardware-oriented PC-based model in SystemView.

A Novel Ancient Coin-Like Fractal Multiband Antenna for Wireless Applications

Directory of Open Access Journals (Sweden)

Zhen Yu

2017-01-01

Full Text Available This study proposes a novel square-circle structure fractal multibroadband planar antenna, similar to an ancient Chinese coin-like structure, for second generation (2G, third generation (3G, fourth generation (4G, WLAN, and navigation wireless applications. The device is based on the principles and structural features of conventional monopole antenna elements, combined with the advantages of microstrip antennas and fractal geometry. A fractal method was presented for circular nested square slotted structures, similar to an ancient Chinese copper coin. The proposed antenna adapted five iterations on a fractal structure radiator, which covers more than ten mobile applications in three broad frequency bands with a bandwidth of 70% (1.43–2.97 GHz for DCS1800, TD-SCDMA, WCDMA, CDMA2000, LTE33-41, Bluetooth, GPS (Global Positioning System, BDS (BeiDou Navigation Satellite System, GLONSS (Global Navigation Satellite System, GALILEO (Galileo Satellite Navigation System, and WLAN frequency bands, 16.32% (3.32–3.91 GHz for LTE42, LTE43, and WiMAX frequency bands, and 10.92% (4.85–5.41 GHz for WLAN frequency band. The proposed antenna was fabricated on a 1.6 mm thick G10/FR4 substrate with a dielectric constant of 4.4 and a size of 88.5 × 60 mm2. The measurement results reveal that the omnidirectional radiation patterns achieve a gain of 1.16–3.75 dBi and an efficiency of 40–72%. The good agreement between the measurement results and simulation validates the proposed design approach and satisfies the requirements for various wireless applications.

Coherent Code Tracking for Spatial Transmit Diversity DS-CDMA Systems

Directory of Open Access Journals (Sweden)

R. W. Stewart

2005-09-01

Full Text Available Spatial transmit diversity schemes are now well integrated into third-generation cellular mobile communication system specifications. When DS-CDMA-based technology is deployed in typical macro- and microcell environments, multipath diversity and spatial diversity may be exploited simultaneously by a 2D RAKE receiver. The work presented in this paper focuses on taking advantage of spatial transmit diversity in synchronising the 2D RAKE structure. We investigate the use of coherent and noncoherent techniques for tracking the timing parameters of each multipath component. It is shown that both noncoherent and coherent techniques benefit from transmit diversity. Additionally the performance gap between these two techniques increases with the number of antennas.

Energy Aware Computing in Cooperative Wireless Networks

DEFF Research Database (Denmark)

Olsen, Anders Brødløs; Fitzek, Frank H. P.; Koch, Peter

2005-01-01

In this work the idea of cooperation is applied to wireless communication systems. It is generally accepted that energy consumption is a significant design constraint for mobile handheld systems. We propose a novel method of cooperative task computing by distributing tasks among terminals over...... the unreliable wireless link. Principles of multi–processor energy aware task scheduling are used exploiting performance scalable technologies such as Dynamic Voltage Scaling (DVS). We introduce a novel mechanism referred to as D2VS and here it is shown by means of simulation that savings of 40% can be achieved....

Ultra Secure High Reliability Wireless Radiation Monitor

International Nuclear Information System (INIS)

Cordaro, J.; Shull, D.; Farrar, M.; Reeves, G.

2011-01-01

Radiation monitoring in nuclear facilities is essential to safe operation of the equipment as well as protecting personnel. In specific, typical air monitoring of radioactive gases or particulate involves complex systems of valves, pumps, piping and electronics. The challenge is to measure a representative sample in areas that are radioactively contaminated. Running cables and piping to these locations is very expensive due to the containment requirements. Penetration into and out of an airborne or containment area is complex and costly. The process rooms are built with thick rebar-enforced concrete walls with glove box containment chambers inside. Figure 1 shows high temperature radiation resistance cabling entering the top of a typical glove box. In some case, the entire processing area must be contained in a 'hot cell' where the only access into the chamber is via manipulators. An example is shown in Figure 2. A short range wireless network provides an ideal communication link for transmitting the data from the radiation sensor to a 'clean area', or area absent of any radiation fields or radioactive contamination. Radiation monitoring systems that protect personnel and equipment must meet stringent codes and standards due to the consequences of failure. At first glance a wired system would seem more desirable. Concerns with wireless communication include latency, jamming, spoofing, man in the middle attacks, and hacking. The Department of Energy's Savannah River National Laboratory (SRNL) has developed a prototype wireless radiation air monitoring system that address many of the concerns with wireless and allows quick deployment in radiation and contamination areas. It is stand alone and only requires a standard 120 VAC, 60 Hz power source. It is designed to be mounted or portable. The wireless link uses a National Security Agency (NSA) Suite B compliant wireless network from Fortress Technologies that is considered robust enough to be used for classified data

ULTRA SECURE HIGH RELIABILITY WIRELESS RADIATION MONITOR

Energy Technology Data Exchange (ETDEWEB)

Cordaro, J.; Shull, D.; Farrar, M.; Reeves, G.

2011-08-03

Radiation monitoring in nuclear facilities is essential to safe operation of the equipment as well as protecting personnel. In specific, typical air monitoring of radioactive gases or particulate involves complex systems of valves, pumps, piping and electronics. The challenge is to measure a representative sample in areas that are radioactively contaminated. Running cables and piping to these locations is very expensive due to the containment requirements. Penetration into and out of an airborne or containment area is complex and costly. The process rooms are built with thick rebar-enforced concrete walls with glove box containment chambers inside. Figure 1 shows high temperature radiation resistance cabling entering the top of a typical glove box. In some case, the entire processing area must be contained in a 'hot cell' where the only access into the chamber is via manipulators. An example is shown in Figure 2. A short range wireless network provides an ideal communication link for transmitting the data from the radiation sensor to a 'clean area', or area absent of any radiation fields or radioactive contamination. Radiation monitoring systems that protect personnel and equipment must meet stringent codes and standards due to the consequences of failure. At first glance a wired system would seem more desirable. Concerns with wireless communication include latency, jamming, spoofing, man in the middle attacks, and hacking. The Department of Energy's Savannah River National Laboratory (SRNL) has developed a prototype wireless radiation air monitoring system that address many of the concerns with wireless and allows quick deployment in radiation and contamination areas. It is stand alone and only requires a standard 120 VAC, 60 Hz power source. It is designed to be mounted or portable. The wireless link uses a National Security Agency (NSA) Suite B compliant wireless network from Fortress Technologies that is considered robust enough to be

Transport Schemes for Fiber-Wireless Technology: Transmission Performance and Energy Efficiency

Directory of Open Access Journals (Sweden)

Christina Lim

2014-04-01

Full Text Available Fiber-wireless technology has been actively researched as a potential candidate for next generation broadband wireless signal distribution. Despite the popularity, this hybrid scheme has many technical challenges that impede the uptake and commercial deployment. One of the inherent issues is the transport of the wireless signals over a predominantly digital optical network in today’s telecommunication infrastructure. Many different approaches have been introduced and demonstrated with digitized RF transport of the wireless signals being the most compatible with the existing optical fiber networks. In this paper, we review our work in the area of digitized RF transport to address the inherent issues related to analog transport in the fiber-wireless links and compare the transmission performance and energy efficiency with the other transport strategies.

A novel adaptive joint power control algorithm with channel estimation in a CDMA cellular system

Institute of Scientific and Technical Information of China (English)

无

2005-01-01

Joint power control has advantages of multi-user detection and power control; and it can combat the multi-access interference and the near-far problem. A novel adaptive joint power control algorithm with channel estimation in a CDMA cellular system was designed. Simulation results show that the algorithm can control the power not only quickly but also precisely with a time change. The method is useful for increasing system capacity.

Network coding and evolutionary theory for performance enhancement in wireless cooperative clusters

DEFF Research Database (Denmark)

Militano, Leonardo; Fitzek, Frank; Iera, Antonio

2010-01-01

Cooperation over short-range wireless links among user devices, which download remote contents through cellular links, is a paradigm quickly gaining ground, given that it can answer several technological and design issues that next-generation wireless applications will raise. Among others, energy...... are investigated and an ad hoc conceived Genetic Algorithm (GA) designed. Either the service time (the time needed for all nodes to receive the complete file) or the energy consumption for the nodes is used as objective function, showing in both cases the fast convergence for the algorithm that makes it preferable...

CCM-R: Secure Counter Synchronization for IoT Wireless Link

DEFF Research Database (Denmark)

Roy, Upal; Yin, Jiachen; Andersen, Birger

2016-01-01

In this paper we propose and evaluate a new version of the CCM mode of operation, CCM-R, which isan extended and alternate version of the original CBC-MAC with Counter Mode(CCM) that was created to address the problem of counter synchronization. While CCM is considered secure when used/implemente...... it suitable for low-power wireless IoT devices....

Fiber-wireless links supporting high-capacity W-band channels

DEFF Research Database (Denmark)

Vegas Olmos, Juan José; Tafur Monroy, Idelfonso

2013-01-01

Seamless convergence of fiber-optic and the wireless networks is of great interest for enabling transparent delivery of broadband services to users in different locations, including both metropolitan and rural areas. Current demand of bandwidth by end-users, especially using mobile devices...... latest findings and experimental results on the W-band, specifically on its 81-86GHz sub-band. These include photonic generation of millimeter-wave carriers and transmission performance of broadband signals on different types of fibers and span lengths....

Simultaneous Wireless Power Transfer and Data Communication Using Synchronous Pulse-Controlled Load Modulation.

Science.gov (United States)

Mao, Shitong; Wang, Hao; Zhu, Chunbo; Mao, Zhi-Hong; Sun, Mingui

2017-10-01

Wireless Power Transfer (WPT) and wireless data communication are both important problems of research with various applications, especially in medicine. However, these two problems are usually studied separately. In this work, we present a joint study of both problems. Most medical electronic devices, such as smart implants, must have both a power supply to allow continuous operation and a communication link to pass information. Traditionally, separate wireless channels for power transfer and communication are utilized, which complicate the system structure, increase power consumption and make device miniaturization difficult. A more effective approach is to use a single wireless link with both functions of delivering power and passing information. We present a design of such a wireless link in which power and data travel in opposite directions. In order to aggressively miniaturize the implant and reduce power consumption, we eliminate the traditional multi-bit Analog-to-Digital Converter (ADC), digital memory and data transmission circuits all together. Instead, we use a pulse stream, which is obtained from the original biological signal, by a sigma-delta converter and an edge detector, to alter the load properties of the WPT channel. The resulting WPT signal is synchronized with the load changes therefore requiring no memory elements to record inter-pulse intervals. We take advantage of the high sensitivity of the resonant WPT to the load change, and the system dynamic response is used to transfer each pulse. The transient time of the WPT system is analyzed using the coupling mode theory (CMT). Our experimental results show that the memoryless approach works well for both power delivery and data transmission, providing a new wireless platform for the design of future miniaturized medical implants.

Design and Optimization of Ultrasonic Wireless Power Transmission Links for Millimeter-Sized Biomedical Implants.

Science.gov (United States)

Meng, Miao; Kiani, Mehdi

2017-02-01

Ultrasound has been recently proposed as an alternative modality for efficient wireless power transmission (WPT) to biomedical implants with millimeter (mm) dimensions. This paper presents the theory and design methodology of ultrasonic WPT links that involve mm-sized receivers (Rx). For given load (R L ) and powering distance (d), the optimal geometries of transmitter (Tx) and Rx ultrasonic transducers, including their diameter and thickness, as well as the optimal operation frequency (f c ) are found through a recursive design procedure to maximize the power transmission efficiency (PTE). First, a range of realistic f c s is found based on the Rx thickness constrain. For a chosen f c within the range, the diameter and thickness of the Rx transducer are then swept together to maximize PTE. Then, the diameter and thickness of the Tx transducer are optimized to maximize PTE. Finally, this procedure is repeated for different f c s to find the optimal f c and its corresponding transducer geometries that maximize PTE. A design example of ultrasonic link has been presented and optimized for WPT to a 1 mm 3 implant, including a disk-shaped piezoelectric transducer on a silicon die. In simulations, a PTE of 2.11% at f c of 1.8 MHz was achieved for R L of 2.5 [Formula: see text] at [Formula: see text]. In order to validate our simulations, an ultrasonic link was optimized for a 1 mm 3 piezoelectric transducer mounted on a printed circuit board (PCB), which led to simulated and measured PTEs of 0.65% and 0.66% at f c of 1.1 MHz for R L of 2.5 [Formula: see text] at [Formula: see text], respectively.

A wireless sensor enabled by wireless power.

Science.gov (United States)

Lee, Da-Sheng; Liu, Yu-Hong; Lin, Chii-Ruey

2012-11-22

Through harvesting energy by wireless charging and delivering data by wireless communication, this study proposes the concept of a wireless sensor enabled by wireless power (WPWS) and reports the fabrication of a prototype for functional tests. One WPWS node consists of wireless power module and sensor module with different chip-type sensors. Its main feature is the dual antenna structure. Following RFID system architecture, a power harvesting antenna was designed to gather power from a standard reader working in the 915 MHz band. Referring to the Modbus protocol, the other wireless communication antenna was integrated on a node to send sensor data in parallel. The dual antenna structure integrates both the advantages of an RFID system and a wireless sensor. Using a standard UHF RFID reader, WPWS can be enabled in a distributed area with a diameter up to 4 m. Working status is similar to that of a passive tag, except that a tag can only be queried statically, while the WPWS can send dynamic data from the sensors. The function is the same as a wireless sensor node. Different WPWSs equipped with temperature and humidity, optical and airflow velocity sensors are tested in this study. All sensors can send back detection data within 8 s. The accuracy is within 8% deviation compared with laboratory equipment. A wireless sensor network enabled by wireless power should be a totally wireless sensor network using WPWS. However, distributed WPWSs only can form a star topology, the simplest topology for constructing a sensor network. Because of shielding effects, it is difficult to apply other complex topologies. Despite this limitation, WPWS still can be used to extend sensor network applications in hazardous environments. Further research is needed to improve WPWS to realize a totally wireless sensor network.

Overloaded CDMA Systems with Displaced Binary Signatures

Directory of Open Access Journals (Sweden)

Vanhaverbeke Frederik

2004-01-01

Full Text Available We extend three types of overloaded CDMA systems, by displacing in time the binary signature sequences of these systems: (1 random spreading (PN, (2 multiple-OCDMA (MO, and (3 PN/OCDMA (PN/O. For each of these systems, we determine the time shifts that minimize the overall multiuser interference power. The achievable channel load with coded and uncoded data is evaluated for the conventional (without displacement and improved (with displacement systems, as well as for systems based on quasi-Welch-bound-equality (QWBE sequences, by means of several types of turbo detectors. For each system, the best performing turbo detector is selected in order to compare the performance of these systems. It is found that the improved systems substantially outperform their original counterparts. With uncoded data, (improved PN/O yields the highest acceptable channel load. For coded data, MO allows for the highest acceptable channel load over all considered systems, both for the conventional and the improved systems. In the latter case, channel loads of about 280% are achievable with a low degradation as compared to a single user system.

Design of an Omnidirectional Multibeam Transmitter for High-Speed Indoor Wireless Communications

Directory of Open Access Journals (Sweden)

Tang Jaw-Luen

2010-01-01

Full Text Available For future high speed indoor wireless communication, diffuse wireless optical communications offer more robust optical links against shadowing than line-of-sight links. However, their performance may be degraded by multipath dispersion arising from surface reflections. We have developed a multipath diffusive propagation model capable of providing channel impulse responses data. It is aimed to design and simulate any multibeam transmitter under a variety of indoor environments. In this paper, a multi-beam transmitter system associated with hemisphere structure is proposed to fight against the diverse effects of multipath distortion albeit, at the cost of increased laser power and cost. Simulation results of multiple impulse responses showed that this type of multi-beam transmitter can significantly improve the performance of BER suitable for high bit rate application. We present the performance and simulation results for both line-of-sight and diffuse link configurations. We propose a design of power radiation pattern for a transmitter in achieving uniform and full coverage of power distributions for diffuse indoor optical wireless systems.

Resource management for multimedia services in high data rate wireless networks

CERN Document Server

Zhang, Ruonan; Pan, Jianping

2017-01-01

This brief offers a valuable resource on principles of quality-of-service (QoS) provisioning and the related link-layer resource management techniques for high data-rate wireless networks. The primary emphasis is on protocol modeling and analysis. It introduces media access control (MAC) protocols, standards of wireless local area networks (WLANs), wireless personal area networks (WPANs), and wireless body area networks (WBANs), discussing their key technologies, applications, and deployment scenarios. The main analytical approaches and models for performance analysis of the fundamental resource scheduling mechanisms, including the contention-based, reservation-based, and hybrid MAC, are presented. To help readers understand and evaluate system performance, the brief contains a range of simulation results. In addition, a thorough bibliography provides an additional tool. This brief is an essential resource for engineers, researchers, students, and users of wireless networks.

Evolution to 3G Mobile Communication - Second Generation ...

Indian Academy of Sciences (India)

Home; Journals; Resonance – Journal of Science Education; Volume 8; Issue 9. Evolution to 3G Mobile Communication - Second Generation Cellular Systems. R Ramachandran. General Article Volume 8 Issue 9 September 2003 pp 60-72 ... Keywords. Wireless communication; cellular networks; GSM; CdmaOne; TDMA ...

Computationally Efficient Chaotic Spreading Sequence Selection for Asynchronous DS-CDMA

Directory of Open Access Journals (Sweden)

Litviņenko Anna

2017-12-01

Full Text Available The choice of the spreading sequence for asynchronous direct-sequence code-division multiple-access (DS-CDMA systems plays a crucial role for the mitigation of multiple-access interference. Considering the rich dynamics of chaotic sequences, their use for spreading allows overcoming the limitations of the classical spreading sequences. However, to ensure low cross-correlation between the sequences, careful selection must be performed. This paper presents a novel exhaustive search algorithm, which allows finding sets of chaotic spreading sequences of required length with a particularly low mutual cross-correlation. The efficiency of the search is verified by simulations, which show a significant advantage compared to non-selected chaotic sequences. Moreover, the impact of sequence length on the efficiency of the selection is studied.

Towards Controlling Latency in Wireless Networks

KAUST Repository

Bouacida, Nader

2017-04-24

Wireless networks are undergoing an unprecedented revolution in the last decade. With the explosion of delay-sensitive applications in the Internet (i.e., online gaming and VoIP), latency becomes a major issue for the development of wireless technology. Taking advantage of the significant decline in memory prices, industrialists equip the network devices with larger buffering capacities to improve the network throughput by limiting packets drops. Over-buffering results in increasing the time that packets spend in the queues and, thus, introducing more latency in networks. This phenomenon is known as “bufferbloat”. While throughput is the dominant performance metric, latency also has a huge impact on user experience not only for real-time applications but also for common applications like web browsing, which is sensitive to latencies in order of hundreds of milliseconds. Concerns have arisen about designing sophisticated queue management schemes to mitigate the effects of such phenomenon. My thesis research aims to solve bufferbloat problem in both traditional half-duplex and cutting-edge full-duplex wireless systems by reducing delay while maximizing wireless links utilization and fairness. Our work shed lights on buffer management algorithms behavior in wireless networks and their ability to reduce latency resulting from excessive queuing delays inside oversized static network buffers without a significant loss in other network metrics. First of all, we address the problem of buffer management in wireless full-duplex networks by using Wireless Queue Management (WQM), which is an active queue management technique for wireless networks. Our solution is based on Relay Full-Duplex MAC (RFD-MAC), an asynchronous media access control protocol designed for relay full-duplexing. Compared to the default case, our solution reduces the end-to-end delay by two orders of magnitude while achieving similar throughput in most of the cases. In the second part of this thesis

LinkMind: Link Optimization in Swarming Mobile Sensor Networks

DEFF Research Database (Denmark)

Ngo, Trung Dung

2012-01-01

of the most advantageous properties of the swarming wireless sensor network is that mobile nodes can work cooperatively to organize an ad-hoc network and optimize the network link capacity to maximize the transmission of gathered data from a source to a target. This paper describes a new method of link...... optimization of swarming mobile sensor networks. The new method is based on combination of the artificial potential force guaranteeing connectivities of the mobile sensor nodes and the max-flow min-cut theorem of graph theory ensuring optimization of the network link capacity. The developed algorithm...

Wireless access to a pharmaceutical database: A demonstrator for data driven Wireless Application Prorocol (WAP) applications in medical information processing

DEFF Research Database (Denmark)

Hansen, Michael Schacht; Dørup, Jens

2001-01-01

script for easy update of the database. Data were distributed in 35 interrelated tables. Each pharmaceutical brand name was given its own card with links to general information about the drug, active substances, contraindications etc. Access was available through 1) browsing therapeutic groups and 2......) searching for a brand name. The database interface was programmed in the server-side scripting language PHP3. RESULTS: A free, open source Wireless Application Protocol gateway to a pharmaceutical catalogue was established to allow dial-in access independent of commercial Wireless Application Protocol...... service providers. The application was tested on the Nokia 7110 and Ericsson R320s cellular phones. CONCLUSIONS: We have demonstrated that Wireless Application Protocol-based access to a dynamic clinical database can be established using open source freeware. The project opens perspectives for a further...

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

Institute of Scientific and Technical Information of China (English)

Jia Min; Chen Huimin; Yuan Yuhua

2007-01-01

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

Single Channel 106 Gbit/s 16QAM Wireless Transmission in the 0.4 THz Band

DEFF Research Database (Denmark)

Pang, Xiaodan; Jia, Shi; Ozolins, Oskars

2017-01-01

We experimentally demonstrate a single channel 32-GBd 16QAM THz wireless link operating in the 0.4 THz band. Post-FEC net data rate of 106 Gbit/s is successfully achieved without any spatial/frequency multiplexing.......We experimentally demonstrate a single channel 32-GBd 16QAM THz wireless link operating in the 0.4 THz band. Post-FEC net data rate of 106 Gbit/s is successfully achieved without any spatial/frequency multiplexing....

VT Wireless Broadband Availability by Census Block - 06-2011

Data.gov (United States)

Vermont Center for Geographic Information — (Link to Metadata) The VTBB201106 VT Broadband Availability Dataset represents wireline and wireless 'broadband service' availability in VT as of 6/30/2011. This...

VT Wireless Broadband Availability by Census Block - 06-2013

Data.gov (United States)

Vermont Center for Geographic Information — (Link to Metadata) The VTBB201306 VT Broadband Availability Dataset represents wireline and wireless 'broadband service' availability in VT as of 6/30/2013. This...

VT Wireless Broadband Availability by Census Block - 12-2012

Data.gov (United States)

Vermont Center for Geographic Information — (Link to Metadata) The VTBB201212 VT Broadband Availability Dataset represents wireline and wireless 'broadband service' availability in VT as of 12/31/2012. This...

VT Wireless Broadband Availability by Census Block - 06-2010

Data.gov (United States)

Vermont Center for Geographic Information — (Link to Metadata) The VTBB201006 VT Broadband Availability Dataset represents wireline and wireless 'broadband service' availability in VT as of 6/30/2010. This...

VT Wireless Broadband Availability by Census Block - 12-2010

Data.gov (United States)

Vermont Center for Geographic Information — (Link to Metadata) The VTBB201012 VT Broadband Availability Dataset represents wireline and wireless 'broadband service' availability in VT as of 12/31/2010. This...

VT Wireless Broadband Availability by Census Block - 12-2011

Data.gov (United States)

Vermont Center for Geographic Information — (Link to Metadata) The VTBB201112 VT Broadband Availability Dataset represents wireline and wireless 'broadband service' availability in VT as of 12/31/2011. This...

Optical wireless communication in data centers

Science.gov (United States)

Arnon, Shlomi

2018-01-01

In the last decade data centers have become a crucial element in modern human society. However, to keep pace with internet data rate growth, new technologies supporting data center should develop. Integration of optical wireless communication (OWC) in data centers is one of the proposed technologies as augmented technology to the fiber network. One implementation of the OWC technology is deployment of optical wireless transceiver on top of the existing cable/fiber network as extension to the top of rack (TOR) switch; in this way, a dynamic and flexible network is created. Optical wireless communication could reduce energy consumption, increase the data rate, reduce the communication latency, increase flexibility and scalability, and reduce maintenance time and cost, in comparison to extra fiber network deployment. In this paper we review up to date literature in the field, propose an implementation scheme of OWC network, discuss ways to reduce energy consumption by parallel link communication and report preliminary measurement result of university data center environment.

Wireless Heart Patients and the Quantified Self

DEFF Research Database (Denmark)

Grew, Julie Christina; Svendsen, Mette Nordahl

2017-01-01

Remote monitoring of implantable cardioverter defibrillator (ICD) patients links patients wirelessly to the clinic via a box in their bedroom. The box transmits data from the ICD to a remote database accessible to clinicians without patient involvement. Data travel across time and space; clinicia...

Simulation Of Wireless Networked Control System Using TRUETIME And MATLAB

Directory of Open Access Journals (Sweden)

Nyan Phyo Aung

2015-08-01

Full Text Available Wireless networked control systems WNCS are attracting an increasing research interests in the past decade. Wireless networked control system WNCS is composed of a group of distributed sensors and actuators that communicate through wireless link which achieves distributed sensing and executing tasks. This is particularly relevant for the areas of communication control and computing where successful design of WNCS brings about new challenges to the researchers. The primary motivation of this survey paper is to examine the design issues and to provide directions for successful simulation and implementation of WNCS. The paper also as well reviews some simulation tools for such systems.

Design and implementation of the wireless high voltage control system

International Nuclear Information System (INIS)

Srivastava, Saurabh; Misra, A.; Pandey, H.K.; Thakur, S.K.; Pandit, V.S.

2011-01-01

In this paper we will describe the implementation of the wireless link for controlling and monitoring the serial data between control PC and the interface card (general DAQ card), by replacing existing RS232 based remote control system for controlling and monitoring High Voltage Power Supply (120kV/50mA). The enhancement in the reliability is achieved by replacing old RS232 based control system with wireless system by isolating ground loop. (author)

Secure DS-CDMA spreading codes using fully digital multidimensional multiscroll chaos

KAUST Repository

Mansingka, Abhinav S.

2014-06-18

This paper introduces a generalized fully digital hardware implementation of 1-D, 2-D and 3-D multiscroll chaos through sawtooth nonlinearities in a 3rd order ODE with the Euler approximation, wherein low-significance bits pass all NIST SP. 800-22 tests. The low-significance bits show good performance as spreading code for multiple-access DS-CDMA in AWGN and multipath environments, equivalent to Gold codes. This system capitalizes on complex nonlinear dynamics afforded by multiscroll chaos to provide higher security than conventional codes with the same BER performance demonstrated experimentally on a Xilinx Virtex 4 FPGA with logic utilization less than 1.25% and throughput up to 10.92 Gbits/s.

Location based Network Optimizations for Mobile Wireless Networks

DEFF Research Database (Denmark)

Nielsen, Jimmy Jessen

selection in Wi-Fi networks and predictive handover optimization in heterogeneous wireless networks. The investigations in this work have indicated that location based network optimizations are beneficial compared to typical link measurement based approaches. Especially the knowledge of geographical...

Performance Analysis of Iterative Channel Estimation and Multiuser Detection in Multipath DS-CDMA Channels

Science.gov (United States)

Li, Husheng; Betz, Sharon M.; Poor, H. Vincent

2007-05-01

This paper examines the performance of decision feedback based iterative channel estimation and multiuser detection in channel coded aperiodic DS-CDMA systems operating over multipath fading channels. First, explicit expressions describing the performance of channel estimation and parallel interference cancellation based multiuser detection are developed. These results are then combined to characterize the evolution of the performance of a system that iterates among channel estimation, multiuser detection and channel decoding. Sufficient conditions for convergence of this system to a unique fixed point are developed.

40-Gb/s PDM-QPSK signal transmission over 160-m wireless distance at W-band.

Science.gov (United States)

Xiao, Jiangnan; Yu, Jianjun; Li, Xinying; Xu, Yuming; Zhang, Ziran; Chen, Long

2015-03-15

We experimentally demonstrate a W-band optical-wireless transmission system over 160-m wireless distance with a bit rate up to 40 Gb/s. The optical-wireless transmission system adopts optical polarization-division-multiplexing (PDM), multiple-input multiple-output (MIMO) reception and antenna polarization diversity. Using this system, we experimentally demonstrate the 2×2 MIMO wireless delivery of 20- and 40-Gb/s PDM quadrature-phase-shift-keying (PDM-QPSK) signals over 640- and 160-m wireless links, respectively. The bit-error ratios (BERs) of these transmission systems are both less than the forward-error-correction (FEC) threshold of 3.8×10-3.

Emulating Wired Backhaul with Wireless Network Coding

DEFF Research Database (Denmark)

Thomsen, Henning; De Carvalho, Elisabeth; Popovski, Petar

2014-01-01

In this paper we address the need for wireless network densification. We propose a solution wherein the wired backhaul employed in heterogeneous cellular networks is replaced with wireless links, while maintaining the rate requirements of the uplink and downlink traffic of each user. The first...... of the two-way protocol. The transmit power is set high enough to enable successive decoding at the small cell base station where the downlink data to the user is first decoded and its contribution removed from the received signal followed by the uplink data from the user. The decoding of the second layer......, the uplink traffic to the user, remains identical to the one performed in a wired system. In the broadcast phase, the decoding of the downlink traffic can also be guaranteed to remain identical. Hence, our solution claims an emulation of a wired backhaul with wireless network coding with same performance. We...

Cross-Layer Techniques for Adaptive Video Streaming over Wireless Networks

Directory of Open Access Journals (Sweden)

Yufeng Shan

2005-02-01

Full Text Available Real-time streaming media over wireless networks is a challenging proposition due to the characteristics of video data and wireless channels. In this paper, we propose a set of cross-layer techniques for adaptive real-time video streaming over wireless networks. The adaptation is done with respect to both channel and data. The proposed novel packetization scheme constructs the application layer packet in such a way that it is decomposed exactly into an integer number of equal-sized radio link protocol (RLP packets. FEC codes are applied within an application packet at the RLP packet level rather than across different application packets and thus reduce delay at the receiver. A priority-based ARQ, together with a scheduling algorithm, is applied at the application layer to retransmit only the corrupted RLP packets within an application layer packet. Our approach combines the flexibility and programmability of application layer adaptations, with low delay and bandwidth efficiency of link layer techniques. Socket-level simulations are presented to verify the effectiveness of our approach.

Genetic Local Search for Optimum Multiuser Detection Problem in DS-CDMA Systems

Science.gov (United States)

Wang, Shaowei; Ji, Xiaoyong

Optimum multiuser detection (OMD) in direct-sequence code-division multiple access (DS-CDMA) systems is an NP-complete problem. In this paper, we present a genetic local search algorithm, which consists of an evolution strategy framework and a local improvement procedure. The evolution strategy searches the space of feasible, locally optimal solutions only. A fast iterated local search algorithm, which employs the proprietary characteristics of the OMD problem, produces local optima with great efficiency. Computer simulations show the bit error rate (BER) performance of the GLS outperforms other multiuser detectors in all cases discussed. The computation time is polynomial complexity in the number of users.

Information Theoretical Limits of Free-Space Optical Links

KAUST Repository

Ansari, Imran Shafique

2016-08-25

Generalized fading has been an imminent part and parcel of wireless communications. It not only characterizes the wireless channel appropriately but also allows its utilization for further performance analysis of various types of wireless communication systems. Under the umbrella of generalized fading channels, a unified ergodic capacity analysis of a free-space optical (FSO) link under both types of detection techniques (i.e., intensity modulation/direct detection (IM/DD) as well as heterodyne detection) over generalized atmospheric turbulence channels that account for generalized pointing errors is presented. Specifically, unified exact closed-form expressions for the moments of the end-to-end signal-to-noise ratio (SNR) of a single link FSO transmission system are presented. Subsequently, capitalizing on these unified statistics, unified exact closed-form expressions for ergodic capacity performance metric of FSO link transmission systems is offered. Additionally, for scenarios wherein the exact closed-form solution is not possible to obtain, some asymptotic results are derived in the high SNR regime. All the presented results are verified via computer-based Monte-Carlo simulations.

Experimental demonstration of all-optical CDMA using bipolar codes

Science.gov (United States)

Dennis, Tasshi

1999-10-01

Fiber optic networks capable of supporting a large pool of subscribers, many simultaneous users, and high data rates are receiving heightened interest as solutions to a growing communications need. The experiments reported in this study constitute the first experimental demonstration of a novel bipolar equivalent code-division multiple-access (CDMA) scheme. The sophisticated encoding increases noise tolerance, provides user security, and enables network flexibility. The scheme is based on an established bipolar radio frequency (RF) technique adapted to the unipolar optical domain. Whereas the phase of an RF signal can be readily detected, the high carrier frequency ( ~ 200 THz at 1.5 μm) of an optical wave necessitates that optical signals be detected and processed solely by intensity. Asynchronous operation makes the CDMA scheme data rate independent, while all-optical implementation avoids the bandwidth limitations imposed by electrical processing. A proof-of-principle experiment was conducted by spectrally encoding an erbium-doped superfluorescent fiber source (SFS) using a diffraction grating and an amplitude mask. The optical properties of the system were measured and the bipolar correlation of codes was verified. The practical implementation of the scheme was investigated by the design, construction, and operation of a fiber-based testbed. Correlation measurements performed with modulated signals confirmed that the scheme can recover a binary information symbol while rejecting multiple access interference. A theoretical analysis of the optical correlation process was conducted, which identified key optical parameters important to future implementations. The theory of excess noise associated with the photodetection of a thermal source was considered, followed by noise measurements of a light bulb and the erbium-doped SFS used for spectral encoding. Finally, the ability of the proposed scheme to effectively transmit data was investigated. Signal-to- noise

Adapting cognitive radio technology for low-power wireless personal area network devices

DEFF Research Database (Denmark)

Toftegaard, Thomas Skjødeberg; Rohde, John

2011-01-01

The application of wireless personal area network (WPAN) and simple point-to-point wireless communication devices has increased drastically both in private household and in our workspaces in general over the last decade. Combined with the fact that the total number of wireless devices...... and associated standards present in the wireless environment is experiencing an extreme growth, the frequency spectrum scarcity is exposed as a severe challenge. Setting up efficient and reliable wireless WPAN links can be challenging even today. This is especially true because of the intensive use...... discusses the challenges associated with the implementation of highly reliable low-power WPAN networks for the future and the adaption of Cognitive Radio technology as a potential solution. A brief status on the maturity of CR technology will be presented as an integral part of this discussion....

Wireless visual sensor network resource allocation using cross-layer optimization

Science.gov (United States)

Bentley, Elizabeth S.; Matyjas, John D.; Medley, Michael J.; Kondi, Lisimachos P.

2009-01-01

In this paper, we propose an approach to manage network resources for a Direct Sequence Code Division Multiple Access (DS-CDMA) visual sensor network where nodes monitor scenes with varying levels of motion. It uses cross-layer optimization across the physical layer, the link layer and the application layer. Our technique simultaneously assigns a source coding rate, a channel coding rate, and a power level to all nodes in the network based on one of two criteria that maximize the quality of video of the entire network as a whole, subject to a constraint on the total chip rate. One criterion results in the minimal average end-to-end distortion amongst all nodes, while the other criterion minimizes the maximum distortion of the network. Our approach allows one to determine the capacity of the visual sensor network based on the number of nodes and the quality of video that must be transmitted. For bandwidth-limited applications, one can also determine the minimum bandwidth needed to accommodate a number of nodes with a specific target chip rate. Video captured by a sensor node camera is encoded and decoded using the H.264 video codec by a centralized control unit at the network layer. To reduce the computational complexity of the solution, Universal Rate-Distortion Characteristics (URDCs) are obtained experimentally to relate bit error probabilities to the distortion of corrupted video. Bit error rates are found first by using Viterbi's upper bounds on the bit error probability and second, by simulating nodes transmitting data spread by Total Square Correlation (TSC) codes over a Rayleigh-faded DS-CDMA channel and receiving that data using Auxiliary Vector (AV) filtering.

Simplified Fiber-Wireless Distribution of HD Video in Passive and Active W-band Close Proximity Terminals

DEFF Research Database (Denmark)

Lebedev, Alexander; Rodes Lopez, Roberto; Yu, Xianbin

2012-01-01

We experimentally demonstrate uncompressed high-definition (HD) video distribution at 84 GHz Radio over Fiber link achieving up to 3 meters of wireless transmission. We experimentally emulate Metro-Access architecture by deploying single/multimode fibers. Passive and active approaches for remote...... antenna unit (RAU) are experimentally investigated. The bit error rate (BER) performance of the optical and wireless channels is reported. A successful transmission of uncompressed HD video in the W-band wireless channel is demonstrated with prospects to pave the way for application-focused fiber-wireless...

Wireless data transfer with mm-waves for future tracking detectors

International Nuclear Information System (INIS)

Pelikan, D.; Bingefors, N.; Brenner, R.; Gustafsson, L.; Dancila, D.

2014-01-01

Wireless data transfer has revolutionized the consumer market for the last decade generating many products equipped with transmitters and receivers for wireless data transfer. Wireless technology opens attractive possibilities for data transfer in future tracking detectors. The reduction of wires and connectors for data links is certainly beneficial both for the material budget and the reliability of the system. An advantage of wireless data transfer is the freedom of routing signals which today is particularly complicated when bringing the data the first 50 cm out of the tracker. With wireless links intelligence can be built into a tracker by introducing communication between tracking layers within a region of interest which would allow the construction of track primitives in real time. The wireless technology used in consumer products is however not suitable for tracker readouts. The low data transfer capacity of current 5 GHz transceivers and the relatively large feature sizes of the components is a disadvantage.Due to the requirement of high data rates in tracking detectors high bandwidth is required. The frequency band around 60 GHz turns out to be a very promising candidate for data transfer in a detector system. The high baseband frequency allows for data transfer in the order of several Gbit/s. Due to the small wavelength in the mm range only small structures are needed for the transmitting and receiving electronics. The 60 GHz frequency band is a strong candidate for future WLAN applications hence components are already starting to be available on the market.Patch antennas produced on flexible Printed Circuit Board substrate that can be used for wireless communication in future trackers are presented in this article. The antennas can be connected to transceivers for data transmission/reception or be connected by wave-guides to structures capable of bringing the 60 GHz signal behind boundaries. Results on simulation and fabrication of these antennas are

Wireless data transfer with mm-waves for future tracking detectors

Science.gov (United States)

Pelikan, D.; Bingefors, N.; Brenner, R.; Dancila, D.; Gustafsson, L.

2014-11-01

Wireless data transfer has revolutionized the consumer market for the last decade generating many products equipped with transmitters and receivers for wireless data transfer. Wireless technology opens attractive possibilities for data transfer in future tracking detectors. The reduction of wires and connectors for data links is certainly beneficial both for the material budget and the reliability of the system. An advantage of wireless data transfer is the freedom of routing signals which today is particularly complicated when bringing the data the first 50 cm out of the tracker. With wireless links intelligence can be built into a tracker by introducing communication between tracking layers within a region of interest which would allow the construction of track primitives in real time. The wireless technology used in consumer products is however not suitable for tracker readouts. The low data transfer capacity of current 5 GHz transceivers and the relatively large feature sizes of the components is a disadvantage.Due to the requirement of high data rates in tracking detectors high bandwidth is required. The frequency band around 60 GHz turns out to be a very promising candidate for data transfer in a detector system. The high baseband frequency allows for data transfer in the order of several Gbit/s. Due to the small wavelength in the mm range only small structures are needed for the transmitting and receiving electronics. The 60 GHz frequency band is a strong candidate for future WLAN applications hence components are already starting to be available on the market.Patch antennas produced on flexible Printed Circuit Board substrate that can be used for wireless communication in future trackers are presented in this article. The antennas can be connected to transceivers for data transmission/reception or be connected by wave-guides to structures capable of bringing the 60 GHz signal behind boundaries. Results on simulation and fabrication of these antennas are

Design and Implementation of Secure and Reliable Communication using Optical Wireless Communication

Science.gov (United States)

Saadi, Muhammad; Bajpai, Ambar; Zhao, Yan; Sangwongngam, Paramin; Wuttisittikulkij, Lunchakorn

2014-11-01

Wireless networking intensify the tractability in the home and office environment to connect the internet without wires but at the cost of risks associated with stealing the data or threat of loading malicious code with the intention of harming the network. In this paper, we proposed a novel method of establishing a secure and reliable communication link using optical wireless communication (OWC). For security, spatial diversity based transmission using two optical transmitters is used and the reliability in the link is achieved by a newly proposed method for the construction of structured parity check matrix for binary Low Density Parity Check (LDPC) codes. Experimental results show that a successful secure and reliable link between the transmitter and the receiver can be achieved by using the proposed novel technique.

Wavelet based multicarrier code division multiple access ...

African Journals Online (AJOL)

This paper presents the study on Wavelet transform based Multicarrier Code Division Multiple Access (MC-CDMA) system for a downlink wireless channel. The performance of the system is studied for Additive White Gaussian Noise Channel (AWGN) and slowly varying multipath channels. The bit error rate (BER) versus ...

Novel method for water vapour monitoring using wireless communication networks measurements

Science.gov (United States)

David, N.; Alpert, P.; Messer, H.

2010-09-01

We propose a new technique for monitoring near-surface water vapour, by estimating humidity from data collected through existing wireless communication networks. Weather conditions and atmospheric phenomena affect the electromagnetic channel, causing attenuations to the radio signals. Thus, wireless communication networks are in effect built-in environmental monitoring facilities. The wireless microwave links, used in these networks, are widely deployed by cellular providers for backhaul communication between base stations, a few tens of meters above ground level. As a result, if all available measurements are used, the proposed method can provide moisture observations with high spatial resolution and potentially high temporal resolution. Further, the implementation cost is minimal, since the data used are already collected and saved by the cellular operators. In addition - many of these links are installed in areas where access is difficult such as orographic terrain and complex topography. As such, our method enables measurements in places that have been hard to measure in the past, or have never been measured before. The technique is restricted to weather conditions which exclude rain, fog or clouds along the propagation path. Strong winds that may cause movement of the link transmitter or receiver (or both) may also interfere with the ability to conduct accurate measurements. We present results from real-data measurements taken from microwave links used in a backhaul cellular network that show very good correlation with surface station humidity measurements (comparisons were performed for several links, found at different locations, during different time periods, showing correlations in the range of 0.5-0.9).

Single- and Multiband OFDM Photonic Wireless Links in the 75−110 GHz Band Employing Optical Combs

DEFF Research Database (Denmark)

Beltrán, M.; Deng, Lei; Pang, Xiaodan

2012-01-01

, allowing the cost and energy efficiency of the system to be increased and supporting different users in the system. Four channels at 9.6 Gb/s/ch in 14.4-GHz bandwidth are generated and transmitted over up to 1.3-m wireless distance. The transmission of a 9.6-Gb/s single-channel signal occupying 3.2-GHz......The photonic generation of electrical orthogonal frequency-division multiplexing (OFDM) modulated wireless signals in the 75−110 GHz band is experimentally demonstrated employing in-phase/quadrature electrooptical modulation and optical heterodyn upconversion. The wireless transmission of 16......-quadrature-amplitude-modulation OFDM signals is demonstrated with a bit error rate performance within the forward error correction limits. Signals of 19.1 Gb/s in 6.3-GHz bandwidth are transmitted over up to 1.3-m wireless distance. Optical comb generation is further employed to support different channels...

A Low-Complexity Joint Synchronization and Detection Algorithm for Single-Band DS-CDMA UWB Communications

Directory of Open Access Journals (Sweden)

Christensen Lars PB

2005-01-01

Full Text Available The problem of asynchronous direct-sequence code-division multiple-access (DS-CDMA detection over the ultra-wideband (UWB multipath channel is considered. A joint synchronization, channel-estimation, and multiuser detection scheme based on the adaptive linear minimum mean square error (LMMSE receiver is presented and evaluated. Further, a novel nonrecursive least-squares algorithm capable of reducing the complexity of the adaptation in the receiver while preserving the advantages of the recursive least-squares (RLS algorithm is presented.

Fresh Prime Codes Evaluation for Synchronous PPM and OPPM Signaling for Optical CDMA Networks

Science.gov (United States)

Karbassian, M. Massoud; Ghafouri-Shiraz, H.

2007-06-01

In this paper, we have proposed a novel prime spreading sequence family hereby referred to as “Double-Padded Modified Prime Code (DPMPC)” for direct-detection synchronous optical code-division multiple-access (OCDMA) networks. The new code is applied to both pulse-position and overlapping pulse-position modulation CDMA networks, and their performances were evaluated and compared with existing prime codes family. In addition, we have analyzed the system throughput and also introduced a new interference cancellation technique which significantly improves the bit error probability of OCDMA networks.

Wireless embedded control system for atomically precise manufacturing

KAUST Repository

Khan, Yasser; Randall, John N.

2011-01-01

This paper will explore the possibilities of implementing a wireless embedded control system for atomically precise manufacturing. The manufacturing process, similar to Scanning Tunneling Microscopy, takes place within an Ultra High Vacuum (UHV) chamber at a pressure of 10-10 torr. In order to create vibration isolation, and to keep internal noise to a minimum, a wireless link inside the UHV chamber becomes essential. We present a MATLAB simulation of the problem, and then demonstrate a hardware scheme between a Gumstix computer and a Linux based laptop for controlling nano-manipulators with three degrees of freedom. © 2011 IEEE.

Wireless embedded control system for atomically precise manufacturing

KAUST Repository

Khan, Yasser

2011-04-01

This paper will explore the possibilities of implementing a wireless embedded control system for atomically precise manufacturing. The manufacturing process, similar to Scanning Tunneling Microscopy, takes place within an Ultra High Vacuum (UHV) chamber at a pressure of 10-10 torr. In order to create vibration isolation, and to keep internal noise to a minimum, a wireless link inside the UHV chamber becomes essential. We present a MATLAB simulation of the problem, and then demonstrate a hardware scheme between a Gumstix computer and a Linux based laptop for controlling nano-manipulators with three degrees of freedom. © 2011 IEEE.

Cross Layer Interference Management in Wireless Biomedical Networks

Directory of Open Access Journals (Sweden)

Emmanouil G. Spanakis

2014-04-01

Full Text Available Interference, in wireless networks, is a central phenomenon when multiple uncoordinated links share a common communication medium. The study of the interference channel was initiated by Shannon in 1961 and since then this problem has been thoroughly elaborated at the Information theoretic level but its characterization still remains an open issue. When multiple uncoordinated links share a common medium the effect of interference is a crucial limiting factor for network performance. In this work, using cross layer cooperative communication techniques, we study how to compensate interference in the context of wireless biomedical networks, where many links transferring biomedical or other health related data may be formed and suffer from all other interfering transmissions, to allow successful receptions and improve the overall network performance. We define the interference limited communication range to be the critical communication region around a receiver, with a number of surrounding interfering nodes, within which a successful communication link can be formed. Our results indicate that we can achieve more successful transmissions by adapting the transmission rate and power, to the path loss exponent, and the selected mode of the underline communication technique allowing interference mitigation and when possible lower power consumption and increase achievable transmission rates.

Wireless sensor network performance metrics for building applications

Energy Technology Data Exchange (ETDEWEB)

Jang, W.S. (Department of Civil Engineering Yeungnam University 214-1 Dae-Dong, Gyeongsan-Si Gyeongsangbuk-Do 712-749 South Korea); Healy, W.M. [Building and Fire Research Laboratory, 100 Bureau Drive, Gaithersburg, MD 20899-8632 (United States)

2010-06-15

Metrics are investigated to help assess the performance of wireless sensors in buildings. Wireless sensor networks present tremendous opportunities for energy savings and improvement in occupant comfort in buildings by making data about conditions and equipment more readily available. A key barrier to their adoption, however, is the uncertainty among users regarding the reliability of the wireless links through building construction. Tests were carried out that examined three performance metrics as a function of transmitter-receiver separation distance, transmitter power level, and obstruction type. These tests demonstrated, via the packet delivery rate, a clear transition from reliable to unreliable communications at different separation distances. While the packet delivery rate is difficult to measure in actual applications, the received signal strength indication correlated well with the drop in packet delivery rate in the relatively noise-free environment used in these tests. The concept of an equivalent distance was introduced to translate the range of reliability in open field operation to that seen in a typical building, thereby providing wireless system designers a rough estimate of the necessary spacing between sensor nodes in building applications. It is anticipated that the availability of straightforward metrics on the range of wireless sensors in buildings will enable more widespread sensing in buildings for improved control and fault detection. (author)

Terahertz communication: The opportunities of wireless technology beyond 5G

KAUST Repository

Elayan, Hadeel; Amin, Osama; Shubair, Raed M.; Alouini, Mohamed-Slim

2018-01-01

Over the past years, carrier frequencies used for wireless communications have been increasing to meet bandwidth requirements. The engineering community witnessed the development of wide radio bands such as the millimeter-wave (mmW) frequencies to fulfill the explosive growth of mobile data demand and pave the way towards 5G networks. Other research interests have been steered towards optical wireless communication to allow higher data rates, improve physical security and avoid electromagnetic interference. Nevertheless, a paradigm change in the electromagnetic wireless world has been witnessed with the exploitation of the Terahertz (THz) frequency band (0.1–10 THz). With the dawn of THz technology, which fills the gap between radio and optical frequency ranges, ultimate promise is expected for the next generation of wireless networks. In this paper, the light is shed on a number of opportunities associated with the deployment of the THz wireless links. These opportunities offer a plethora of applications to meet the future communication requirements and satisfy the ever increasing user demand of higher data rates.

Emulation Platform for Cyber Analysis of Wireless Communication Network Protocols

Energy Technology Data Exchange (ETDEWEB)

Van Leeuwen, Brian P. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Eldridge, John M. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

2017-11-01

Wireless networking and mobile communications is increasing around the world and in all sectors of our lives. With increasing use, the density and complexity of the systems increase with more base stations and advanced protocols to enable higher data throughputs. The security of data transported over wireless networks must also evolve with the advances in technologies enabling more capable wireless networks. However, means for analysis of the effectiveness of security approaches and implementations used on wireless networks are lacking. More specifically a capability to analyze the lower-layer protocols (i.e., Link and Physical layers) is a major challenge. An analysis approach that incorporates protocol implementations without the need for RF emissions is necessary. In this research paper several emulation tools and custom extensions that enable an analysis platform to perform cyber security analysis of lower layer wireless networks is presented. A use case of a published exploit in the 802.11 (i.e., WiFi) protocol family is provided to demonstrate the effectiveness of the described emulation platform.

Terahertz communication: The opportunities of wireless technology beyond 5G

KAUST Repository

Elayan, Hadeel

2018-05-17

Over the past years, carrier frequencies used for wireless communications have been increasing to meet bandwidth requirements. The engineering community witnessed the development of wide radio bands such as the millimeter-wave (mmW) frequencies to fulfill the explosive growth of mobile data demand and pave the way towards 5G networks. Other research interests have been steered towards optical wireless communication to allow higher data rates, improve physical security and avoid electromagnetic interference. Nevertheless, a paradigm change in the electromagnetic wireless world has been witnessed with the exploitation of the Terahertz (THz) frequency band (0.1–10 THz). With the dawn of THz technology, which fills the gap between radio and optical frequency ranges, ultimate promise is expected for the next generation of wireless networks. In this paper, the light is shed on a number of opportunities associated with the deployment of the THz wireless links. These opportunities offer a plethora of applications to meet the future communication requirements and satisfy the ever increasing user demand of higher data rates.

Radio frequency identification enabled wireless sensing for intelligent food logistics.

Science.gov (United States)

Zou, Zhuo; Chen, Qiang; Chen, Qing; Uysal, Ismail; Zheng, Lirong

2014-06-13

Future technologies and applications for the Internet of Things (IoT) will evolve the process of the food supply chain and create added value of business. Radio frequency identifications (RFIDs) and wireless sensor networks (WSNs) have been considered as the key technological enablers. Intelligent tags, powered by autonomous energy, are attached on objects, networked by short-range wireless links, allowing the physical parameters such as temperatures and humidities as well as the location information to seamlessly integrate with the enterprise information system over the Internet. In this paper, challenges, considerations and design examples are reviewed from system, implementation and application perspectives, particularly with focus on intelligent packaging and logistics for the fresh food tracking and monitoring service. An IoT platform with a two-layer network architecture is introduced consisting of an asymmetric tag-reader link (RFID layer) and an ad-hoc link between readers (WSN layer), which are further connected to the Internet via cellular or Wi-Fi. Then, we provide insights into the enabling technology of RFID with sensing capabilities. Passive, semi-passive and active RFID solutions are discussed. In particular, we describe ultra-wideband radio RFID which has been considered as one of the most promising techniques for ultra-low-power and low-cost wireless sensing. Finally, an example is provided in the form of an application in fresh food tracking services and corresponding field testing results.

Nonlinear distortion in wireless systems modeling and simulation with Matlab

CERN Document Server

Gharaibeh, Khaled M

2011-01-01

This book covers the principles of modeling and simulation of nonlinear distortion in wireless communication systems with MATLAB simulations and techniques In this book, the author describes the principles of modeling and simulation of nonlinear distortion in single and multichannel wireless communication systems using both deterministic and stochastic signals. Models and simulation methods of nonlinear amplifiers explain in detail how to analyze and evaluate the performance of data communication links under nonlinear amplification. The book addresses the analysis of nonlinear systems

Wireless Infrared Networking in the Duke Paperless Classroom.

Science.gov (United States)

Stetten, George D.; Guthrie, Scott D.

1995-01-01

Discusses wireless (diffuse infrared) networking technology to link laptop computers in a computer programming and numerical methods course at Duke University (North Carolina). Describes products and technologies, and effects on classroom dynamics. Reports on effective instructional strategies for lecture, solving student problems, building shared…

Toward Wireless Health Monitoring via an Analog Signal Compression-Based Biosensing Platform.

Science.gov (United States)

Zhao, Xueyuan; Sadhu, Vidyasagar; Le, Tuan; Pompili, Dario; Javanmard, Mehdi

2018-06-01

Wireless all-analog biosensor design for the concurrent microfluidic and physiological signal monitoring is presented in this paper. The key component is an all-analog circuit capable of compressing two analog sources into one analog signal by the analog joint source-channel coding (AJSCC). Two circuit designs are discussed, including the stacked-voltage-controlled voltage source (VCVS) design with the fixed number of levels, and an improved design, which supports a flexible number of AJSCC levels. Experimental results are presented on the wireless biosensor prototype, composed of printed circuit board realizations of the stacked-VCVS design. Furthermore, circuit simulation and wireless link simulation results are presented on the improved design. Results indicate that the proposed wireless biosensor is well suited for sensing two biological signals simultaneously with high accuracy, and can be applied to a wide variety of low-power and low-cost wireless continuous health monitoring applications.

Strategic Control of 60 GHz Millimeter-Wave High-Speed Wireless Links for Distributed Virtual Reality Platforms

Directory of Open Access Journals (Sweden)

Joongheon Kim

2017-01-01

Full Text Available This paper discusses the stochastic and strategic control of 60 GHz millimeter-wave (mmWave wireless transmission for distributed and mobile virtual reality (VR applications. In VR scenarios, establishing wireless connection between VR data-center (called VR server (VRS and head-mounted VR device (called VRD allows various mobile services. Consequently, utilizing wireless technologies is obviously beneficial in VR applications. In order to transmit massive VR data, the 60 GHz mmWave wireless technology is considered in this research. However, transmitting the maximum amount of data introduces maximum power consumption in transceivers. Therefore, this paper proposes a dynamic/adaptive algorithm that can control the power allocation in the 60 GHz mmWave transceivers. The proposed algorithm dynamically controls the power allocation in order to achieve time-average energy-efficiency for VR data transmission over 60 GHz mmWave channels while preserving queue stabilization. The simulation results show that the proposed algorithm presents desired performance.

Up to 35 Gbps Ultra-Wideband Wireless Data Transmission Links

DEFF Research Database (Denmark)

Puerta Ramírez, Rafael; Rommel, Simon; Vegas Olmos, Juan José

2016-01-01

For the first time Ultra-Wideband record data transmission rates up to 35.1 Gbps and 21.6 Gbps are achieved, compliant with the restrictions on the effective radiated power established by both the United States Federal Communications Commission and the European Electronic Communications Committee......, respectively. To achieve these record bit rates, the multi-band approach of Carrierless Amplitude Phase modulation scheme was employed. Wireless transmissions were achieved with a BER below the 7% FEC threshold of 3.8·10-3 ....

Ultra-miniature wireless temperature sensor for thermal medicine applications.

Science.gov (United States)

Khairi, Ahmad; Hung, Shih-Chang; Paramesh, Jeyanandh; Fedder, Gary; Rabin, Yoed

2011-01-01

This study presents a prototype design of an ultra-miniature, wireless, battery-less, and implantable temperature-sensor, with applications to thermal medicine such as cryosurgery, hyperthermia, and thermal ablation. The design aims at a sensory device smaller than 1.5 mm in diameter and 3 mm in length, to enable minimally invasive deployment through a hypodermic needle. While the new device may be used for local temperature monitoring, simultaneous data collection from an array of such sensors can be used to reconstruct the 3D temperature field in the treated area, offering a unique capability in thermal medicine. The new sensory device consists of three major subsystems: a temperature-sensing core, a wireless data-communication unit, and a wireless power reception and management unit. Power is delivered wirelessly to the implant from an external source using an inductive link. To meet size requirements while enhancing reliability and minimizing cost, the implant is fully integrated in a regular foundry CMOS technology (0.15 μm in the current study), including the implant-side inductor of the power link. A temperature-sensing core that consists of a proportional-to-absolute-temperature (PTAT) circuit has been designed and characterized. It employs a microwatt chopper stabilized op-amp and dynamic element-matched current sources to achieve high absolute accuracy. A second order sigma-delta (Σ-Δ) analog-to-digital converter (ADC) is designed to convert the temperature reading to a digital code, which is transmitted by backscatter through the same antenna used for receiving power. A high-efficiency multi-stage differential CMOS rectifier has been designed to provide a DC supply to the sensing and communication subsystems. This paper focuses on the development of the all-CMOS temperature sensing core circuitry part of the device, and briefly reviews the wireless power delivery and communication subsystems.

Exploiting Phase Diversity for CDMA2000 1X Smart Antenna Base Stations

Science.gov (United States)

Kim, Seongdo; Hyeon, Seungheon; Choi, Seungwon

2004-12-01

A performance analysis of an access channel decoder is presented which exploits a diversity gain due to the independent magnitude of received signals energy at each of the antenna elements of a smart-antenna base-station transceiver subsystem (BTS) operating in CDMA2000 1X signal environment. The objective is to enhance the data retrieval at cellsite during the access period, for which the optimal weight vector of the smart antenna BTS is not available. It is shown in this paper that the access channel decoder proposed in this paper outperforms the conventional one, which is based on a single antenna channel in terms of detection probability of access probe, access channel failure probability, and Walsh-code demodulation performance.

A 30 Gb/s full-duplex bi-directional transmission optical wireless-over fiber integration system at W-band.

Science.gov (United States)

Tang, Chanjuan; Yu, Jianjun; Li, Xinying; Chi, Nan; Xiao, Jiangnan; Tian, Yumin; Zhang, Junwen

2014-01-13

We propose and experimentally demonstrate a full-duplex bi-directional transmission optical wireless-over fiber integration system at W-band (75-100 GHz) with the speed up to 15 Gb/s for both 95.4 GHz link and 88.6 GHz link for the first time. The generation of millimeter-wave (mm-wave) wireless signal is based on the photonic technique by heterodyne mixing of an optical quadrature-phase-shift-keying (QPSK) signal with a free-running light at different wavelength. After 20 km fiber transmission, up to 30 Gb/s mm-wave signal is delivered over 2 m wireless link, and then converted to the optical signal for another 20 km fiber transmission. At the wireless receiver, coherent detection and advanced digital signal processing (DSP) are introduced to improve receiver sensitivity and system performance. With the OSNR of 15 dB, the bit error ratios (BERs) for 10 Gb/s signal transmission at 95.4 GHz and 88.6 GHz are below the forward-error-correction (FEC) threshold of 3.8 × 10(-3) whether post filter is used or not, while the BER for 15 Gb/s QPSK signal employing post filter in the link of 95.4 GHz is 2.9 × 10(-3).

Broadcast of four HD videos with LED ceiling lighting: optical-wireless MAC

Science.gov (United States)

Bouchet, Olivier; Porcon, Pascal; Gueutier, Eric

2011-09-01

The European project "hOME Gigabit Access Network" (OMEGA) targeted various wireless and wired solutions for 1 Gbit/s connectivity in Home Area Networks (HANs). One objective was to evaluate the suitability of optical wireless technologies in two spectral regions: visible light (visible-light communications - VLC) and near infrared (infrared communications - IRC). Several demonstrators have been built, all of them largely relying on overthe- shelf components. The demonstrators included a "wide-area" VLC broadcast link based on LED ceiling lighting and a laser-based high-data-rate "wide-area" IRC prototype. In this paper we discuss an adapted optical-wireless media-access-control (OWMAC) sublayer, which was developed and implemented during the project. It is suitable for both IRC and VLC. The VLC prototype is based on DMT signal processing and provides broadcasting at { 100 Mbit/s over an area of approximately 5 m2. The IRC prototype provides {300 Mbit/s half-duplex communication over an area of approximately 30 m2. The IRC mesh network, composed of one base station and two terminals, is based on OOK modulation, multi-sector transceivers, and an ultra-fast sector switch. After a brief discussion about the design of the optical-wireless data link layer and the optical-wireless switch (OWS) card, we address the card development and implementation. We also present applications for the VLC and IRC prototypes and measurement results regarding the MAC layer.

A full-duplex CATV/wireless-over-fiber lightwave transmission system.

Science.gov (United States)

Li, Chung-Yi; Lu, Hai-Han; Ying, Cheng-Ling; Cheng, Chun-Jen; Lin, Che-Yu; Wan, Zhi-Wei; Chen, Jian-Hua

2015-04-06

A full-duplex CATV/wireless-over-fiber lightwave transmission system consisting of one broadband light source (BLS), two optical interleavers (ILs), one intensity modulator, and one phase modulator is proposed and experimentally demonstrated. The downstream light is optically promoted from 10Gbps/25GHz microwave (MW) data signal to 10Gbps/100GHz and 10Gbps/50GHz millimeter-wave (MMW) data signals in fiber-wireless convergence, and intensity-modulated with 50-550 MHz CATV signal. For up-link transmission, the downstream light is phase-remodulated with 10Gbps/25GHz MW data signal in fiber-wireless convergence. Over a 40-km single-mode fiber (SMF) and a 10-m radio frequency (RF) wireless transport, bit error rate (BER), carrier-to-noise ratio (CNR), composite second-order (CSO), and composite triple-beat (CTB) are observed to perform well in such full-duplex CATV/wireless-over-fiber lightwave transmission systems. This full-duplex 100-GHz/50-GHz/25-GHz/550-MHz lightwave transmission system is an attractive alternative. This transmission system not only presents its advancement in the integration of fiber backbone and CATV/wireless feeder networks, but also it provides the advantages of a communication channel for higher data rates and bandwidth.

Wireless Augmented Reality Prototype (WARP)

Science.gov (United States)

Devereaux, A. S.

1999-01-01

Initiated in January, 1997, under NASA's Office of Life and Microgravity Sciences and Applications, the Wireless Augmented Reality Prototype (WARP) is a means to leverage recent advances in communications, displays, imaging sensors, biosensors, voice recognition and microelectronics to develop a hands-free, tetherless system capable of real-time personal display and control of computer system resources. Using WARP, an astronaut may efficiently operate and monitor any computer-controllable activity inside or outside the vehicle or station. The WARP concept is a lightweight, unobtrusive heads-up display with a wireless wearable control unit. Connectivity to the external system is achieved through a high-rate radio link from the WARP personal unit to a base station unit installed into any system PC. The radio link has been specially engineered to operate within the high- interference, high-multipath environment of a space shuttle or space station module. Through this virtual terminal, the astronaut will be able to view and manipulate imagery, text or video, using voice commands to control the terminal operations. WARP's hands-free access to computer-based instruction texts, diagrams and checklists replaces juggling manuals and clipboards, and tetherless computer system access allows free motion throughout a cabin while monitoring and operating equipment.

Multipass Channel Estimation and Joint Multiuser Detection and Equalization for MIMO Long-Code DS/CDMA Systems

Directory of Open Access Journals (Sweden)

Buzzi Stefano

2006-01-01

Full Text Available The problem of joint channel estimation, equalization, and multiuser detection for a multiantenna DS/CDMA system operating over a frequency-selective fading channel and adopting long aperiodic spreading codes is considered in this paper. First of all, we present several channel estimation and multiuser data detection schemes suited for multiantenna long-code DS/CDMA systems. Then, a multipass strategy, wherein the data detection and the channel estimation procedures exchange information in a recursive fashion, is introduced and analyzed for the proposed scenario. Remarkably, this strategy provides, at the price of some attendant computational complexity increase, excellent performance even when very short training sequences are transmitted, and thus couples together the conflicting advantages of both trained and blind systems, that is, good performance and no wasted bandwidth, respectively. Space-time coded systems are also considered, and it is shown that the multipass strategy provides excellent results for such systems also. Likewise, it is also shown that excellent performance is achieved also when each user adopts the same spreading code for all of its transmit antennas. The validity of the proposed procedure is corroborated by both simulation results and analytical findings. In particular, it is shown that adopting the multipass strategy results in a remarkable reduction of the channel estimation mean-square error and of the optimal length of the training sequence.

Energy-efficient digital and wireless IC design for wireless smart sensing

Science.gov (United States)

Zhou, Jun; Huang, Xiongchuan; Wang, Chao; Tae-Hyoung Kim, Tony; Lian, Yong

2017-10-01

Wireless smart sensing is now widely used in various applications such as health monitoring and structural monitoring. In conventional wireless sensor nodes, significant power is consumed in wirelessly transmitting the raw data. Smart sensing adds local intelligence to the sensor node and reduces the amount of wireless data transmission via on-node digital signal processing. While the total power consumption is reduced compared to conventional wireless sensing, the power consumption of the digital processing becomes as dominant as wireless data transmission. This paper reviews the state-of-the-art energy-efficient digital and wireless IC design techniques for reducing the power consumption of the wireless smart sensor node to prolong battery life and enable self-powered applications.

Medium Access Control in Energy Harvesting - Wireless Sensor Networks

DEFF Research Database (Denmark)

Fafoutis, Xenofon

Focusing on Wireless Sensor Networks (WSN) that are powered by energy harvesting, this dissertation focuses on energy-efficient communication links between senders and receivers that are alternating between active and sleeping states of operation. In particular, the focus lies on Medium Access...

DEVELOPMENT OF WIRELESS TECHNIQUES IN DATA AND POWER TRANSMISSION APPLICATION FOR PARTICLE-PHYSICS DETECTORS

CERN Document Server

Brenner, R; Dehos, C; De Lurgio, P; Djurcic, Z; Drake, G; Gonzales Gimenez, JL; Gustafsson, L; Kim, DW; Locci, E; Pfeiffer, U; Röhrich, D; Rydberg, D; Schöning, A; Siligaris, A; Soltveit, HK; Ullaland, K; Vincent, P; Vasquez, PR; Wiedner, D; Yang, S

2017-01-01

In the WADAPT project described in this Letter of Intent, we propose to develop wireless techniques for data and power transmission in particle-physics detectors. Wireless techniques have developed extremely fast over the last decade and are now mature for being considered as a promising alternative to cables and optical links that would revolutionize the detector design. The WADAPT consortium has been formed to identify the specific needs of different projects that might benefit from wireless techniques with the objective of providing a common platform for research and development in order to optimize effectiveness and cost. The proposed R&D will aim at designing and testing wireless demonstrators for large instrumentation systems.

Improving Multi Access Interference Suppression in Optical CDMA by using all-Optical Signal Processing

Directory of Open Access Journals (Sweden)

T. B. Osadola

2013-06-01

Full Text Available This paper presents the study of a novel all-optical method for processing optical CDMA signals towards improving suppression of multi access interference. The main focus is on incoherent OCDMA systems using multiwavelength 2D-WH/TS codes generated using FBG based encoders and decoders. The MAI suppression capabilities based on its ability to eliminate selective wavelength pulse processing have been shown. A novel transmitter architecture that achieves up to 3dB power saving was also presented. As a result of hardware savings, processing cost will be significantly reduced and power budget improvement resulted in improved performance.

Optimization of hybrid token-CDMA MAC system using cross-layer information

CSIR Research Space (South Africa)

Liu, I-S

2007-08-01

Full Text Available The hybrid MAC scheme is capable to implement in either ad hoc or wireless mesh networks (WMN). For WMN configuration, stations are served as access networks utilizing non-mobile relaying nodes to provide wireless backbone services for nomadic users... University and a PhD degree from University of Cambridge, United Kingdom. His research interests are in the general areas of adaptive signal processing, digital and wireless communications and data networks. Co-author: Professor Hong-Jun Xu...

Terahertz wireless communication based on InP-related devices (Conference Presentation)

Science.gov (United States)

Lee, Eui Su; Kim, Hyun-Soo; Park, Jeong-Woo; Park, Dong Woo; Park, Kyung Hyun

2017-02-01

Recently, a wide interest has been gathered in using terahertz (THz) waves as the carrier waves for the next generation of broadband wireless communications. Upon this objective, the photonics technologies are very attractive for their usefulness in signal generations, modulations and detections with enhanced bandwidth and data rates, and the readiness in combining to the existing fiber-optic or wireless networks. In this paper, as a preliminary step toward the THz wireless communications, a THz wireless interconnection system with a broadband antenna-integrated uni-traveling-carrier photodiode (UTC-PD) and a Shottky-barrier diode (SBD) module will be presented. In our system, optical beating signals are generated and digitally modulated by the optical intensity modulator driven by a pulse pattern generator (PPG). As the receiver a SBD and an IF filter followed by a low-noise preamplifier and a limiting amplifier was used. With a 6-mA photocurrent of the UTC-PD which corresponds to the transmitter output power of about 30 μW at 280 GHz, an error-free (BERdefinition serial digital interface format was successfully transmitted over a wireless link.

An Energy Efficient Adaptive Wireless Link for Farms based on IoT technologies

DEFF Research Database (Denmark)

Blaszczyk, tomasz; Lynggaard, Per

2016-01-01

There is a huge demand for automation infrastructures that increase the efficiency and the commercial potential for the agricultural sector. One approach to achieve these objectives is deploying Internet of Things including its embedded wireless sensor network platform. However, deploying wireles...

An Energy Efficient Adaptive Wireless Link for Farms based on IoT technologies

DEFF Research Database (Denmark)

Blaszczyk, Tomasz; Lynggaard, P.

2015-01-01

There is a huge demand for automation infrastructures that increase the efficiency and the commercial potential for the agricultural sector. One approach to achieve these objectives is deploying Internet of Things including its embedded wireless sensor network platform. However, deploying wireles...

Wireless device monitoring methods, wireless device monitoring systems, and articles of manufacture

Science.gov (United States)

McCown, Steven H [Rigby, ID; Derr, Kurt W [Idaho Falls, ID; Rohde, Kenneth W [Idaho Falls, ID

2012-05-08

Wireless device monitoring methods, wireless device monitoring systems, and articles of manufacture are described. According to one embodiment, a wireless device monitoring method includes accessing device configuration information of a wireless device present at a secure area, wherein the device configuration information comprises information regarding a configuration of the wireless device, accessing stored information corresponding to the wireless device, wherein the stored information comprises information regarding the configuration of the wireless device, comparing the device configuration information with the stored information, and indicating the wireless device as one of authorized and unauthorized for presence at the secure area using the comparing.

"De-Randomizing" Congestion Losses to Improve TCP Performance over Wired-Wireless Networks

National Research Council Canada - National Science Library

Biaz, Saad; Vaidya, Nitin H

2004-01-01

.... With Internet becoming more heterogeneous with more and more wireless error-prone links, a TCP connection may unduly throttle its sending rate and experience poor performance over paths experiencing...

Exploiting Phase Diversity for CDMA2000 1X Smart Antenna Base Stations

Directory of Open Access Journals (Sweden)

Hyeon Seungheon

2004-01-01

Full Text Available A performance analysis of an access channel decoder is presented which exploits a diversity gain due to the independent magnitude of received signals energy at each of the antenna elements of a smart-antenna base-station transceiver subsystem (BTS operating in CDMA2000 1X signal environment. The objective is to enhance the data retrieval at cellsite during the access period, for which the optimal weight vector of the smart antenna BTS is not available. It is shown in this paper that the access channel decoder proposed in this paper outperforms the conventional one, which is based on a single antenna channel in terms of detection probability of access probe, access channel failure probability, and Walsh-code demodulation performance.

38-GHz millimeter wave beam steered fiber wireless systems for 5G indoor coverage: architectures, devices, and links

NARCIS (Netherlands)