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COHERENT DS-CDMA PERFORMANCE IN NAKAGAMI MULTIPATH-FADING

IEEE TRANSACTIONS ON COMMUNICATIONS 1995年第2-4期43卷 1134-1143页

作者： ENG, T MILSTEIN, LB Department of Electrical and Computer Engineering University of California San Diego La Jolla CA USA

The coherent reception of direct sequence-code division multiple access (DS-CDMA) signals in a multipath fading channel is considered. The channel model assumes independent paths with Nakagami fading statistics;this model includes the Rayleigh channel as a special case Pad is a reasonable model for a frequency-selective fading channel. The bit error rate (BER) performance of a RAKE receiver under various multipath fading conditions is derived and evaluated. The results indicate that over 50 users may access the channel (assuming 127 chips per bit) simultaneously under typical fading conditions, and can achieve an uncoded BER of 0.01 with an average received signal-to-noise ratio per bit of 10 dB.

关键词： channel model direct-sequence code-division multiple access bit error rate performance average SNR coherent reception RAKE receivers selective fading Multipath fading Binary digits multi-path fading channel

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ANALYSIS OF A direct-sequence CDMA MOBILE RADIO SYSTEM WITH REDUCED SET OF code sequenceS

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IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY 1995年第3期44卷 525-534页

作者： KIM, DI Department of Electronics Engineering Seoul City University Seoul South Korea

A code-division multiple-access scheme that requires a reduced set of code sequences, in which the size of the set is much less than the number of users in the system, is proposed for mobile radio communications, A direct-sequence spread-spectrum signaling is adopted to exploit the property of high time resolution and combat fading effects through multipath diversity reception. Theoretical performance of the proposed system is analyzed by deriving the collision-free path distribution and determining the proper size of the set without reducing the effect of multipath diversity, In connection with the proposed system, two combining schemes are investigated to characterize the effects of the primary and secondary user interferences and evaluate the behavior of the error rate when compared to the original CDMA system.

关键词： code division multiple access diversity reception fading land mobile radio multipath channels pseudonoise codes radiofrequency interference spread spectrum communication code sequences collision-free path distribution direct-sequence CDMA mobile radio sy Error analysis codes Coding sequence code division multiple access pseudonoise codes Spread spectrum communication diversity reception fading color land mobile radio direct-sequence code-division multiple access Mobile radio systems Radiofrequency interference Multipath channels

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Effective interference: A novel approach for interference modelling and traffic analysis in cdma cellular networks

Effective interference: A novel approach for interference mo...

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IEEE Global Telecommunications Conference

作者： Evans, J Everitt, D UNIV MELBOURNE DEPT ELECT & ELECTR ENGNPARKVILLEVIC 3052AUSTRALIA

ISBN: (纸本)0780325109

This paper presents an analysis of the reverse link capacity of cellular mobile communication networks operating with direct sequence code division multiple access. The emphasis is on dealing with the variability in user locations and on allowing different numbers of users in each cell. Firstly we calculate the distribution function of the interference at a cell site from a single mobile whose position is a random vector in another cell of the network. Using ideas closely related to the effective bandwidth concept from the analysis of call admission control in ATM networks, a method of handling the sum of the interference from arbitrary numbers of users in each cell is presented. This leads to a set of linear constraints that bounds the capacity region of the network and to the assignment of an effective interference to users. Importantly, the method is readily incorporated into a traffic model which allows the stochastic nature of the call arrival process to be analysed and the Erlang capacity of the network to be calculated.

关键词： Traffic Analysis Cellular networks direct-sequence code-division multiple access cell site capacity region Traffic models Distribution function Call admission control random vector Cells code division multiple access

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DS/CDMA with predetection diversity over a frequency selective multipath Rayleigh-fading channel

DS/CDMA with predetection diversity over a frequency selecti...

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IEEE Singapore International Conference on Networks

作者： Wu Shi Ying Do Manh Anh School of Electrical & Electronic Engineering Nanyang Technological University Singapore

ISBN: (纸本)0780325796

This paper investigates the bit error rate performance of a direct sequence code division multiple access (DS/CDMA) system with predetection diversity over a frequency selective multipath Rayleigh-fading channel. Differential phase-shift-keying (DPSK) modulation and noncoherent demodulation are considered. It is shown that predetection diversify is relatively more efficient in improving the BER performance of the system when the channel conditions are worse. If is also shown that a large number of resolvable paths are beneficial when they are all combined to combat the multipath fading.

关键词： Multiaccess communication Frequency diversity Bit error rate direct-sequence code-division multiple access Frequency conversion Rayleigh channels Phase shift keying Differential quadrature phase shift keying Phase modulation Demodulation

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Integration of multirate services using CDMA in an overlaid cellular system

Integration of multirate services using CDMA in an overlaid ...

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IEEE International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC)

作者： S. Chaudry A.U. Sheikh PCS Research Laboratory Department of Systems and Computer Engineering Carleton University Ottawa Canada

In emerging integrated wireless personal communications systems, the users are given freedom to choose a service out of many available. The integration of voice, data and video services to meet the user needs on to a common mode of transmission is a difficult task. An overlaid cellular CDMA system is proposed to carry different rate traffic on the same carrier frequency. It is shown that different rate services can coexists in a DS-CDMA-DFE system without any noticeable impact on the system capacity.

关键词： Multiaccess communication Personal communication networks Bandwidth Frequency Laboratories Systems engineering and theory Delay direct-sequence code-division multiple access Fading Communication system security

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Capacity of DS-CDMA networks on frequency selective fading channels with open-loop power control

Capacity of DS-CDMA networks on frequency selective fading c...

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IEEE International Conference on Communications (ICC)

作者： A. Chockalingam L.B. Milstein Department of Electrical and Computer Engineering University of California La Jolla CA USA

Presents the coded bit error performance for the reverse link of a direct sequence code division multiple access (DS-CDMA) network employing an open-loop power control scheme over a frequency selective Rayleigh fading channel. A quasi-analytical approach has been adopted, where in the uncoded bit error performance is evaluated through simulation and the coded performance is arrived at through analytical bounds. A rate-1/3 convolutional code of constraint length 9, with hard decision Viterbi decoding is considered. The system capacity degradation due to open-loop power control error, which is approximated by a log-normally distributed random variable, is estimated. It is found that, for typical voice applications, the capacity degradation compared to perfect power control remains less than 3% as long as the standard deviation of the power control error (/spl alpha//sub /spl delta//) is less than 1 dB, and increases to 17% when /spl sigma//sub /spl delta// is 2 dB. The study is of interest in cellular networks.

关键词： Multiaccess communication Fading Power control Degradation Error correction Error correction codes direct-sequence code-division multiple access Frequency conversion Analytical models Performance analysis

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OPTIMAL SOFT MULTI-USER DECODING FOR VECTOR QUANTIZATION IN A SYNCHRONOUS CDMA SYSTEM

OPTIMAL SOFT MULTI-USER DECODING FOR VECTOR QUANTIZATION IN ...

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IEEE International Symposium on Information Theory

作者： M. Skoglund T. Ottosson Department of Information Theory Chalmers University of Technology Goteborg Sweden

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Forward-link frequency reuse efficiency of power controlled CDMA cellular system

Forward-link frequency reuse efficiency of power controlled ...

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IEEE International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC)

作者： M.S. Ismail T.A. Rahman Radio Research Group FKE Universiti Teknologi Malaysia Johor Malaysia Radio Res. Group Universiti Teknologi Malaysia Johor Malaysia

The effects of the propagation path loss coefficient (/spl gamma/) and power control on the forward-link frequency reuse efficiency (K) of a direct sequence code division multiple access (CDMA) cellular system is investigated. A simple analytical model is developed to express the interference received by a user in the home cell from other base stations based on the inverse power-of-distance /spl gamma/ law. Proper factors for optimum power control performance are estimated according to /spl gamma/. With these factors, K is improved to twice that without power control for /spl gamma/ between 4.5 and 2.5. The degradation in K as /spl gamma/ is increased is significantly less for CDMA than for the traditional FDMA and TDMA cellular systems.

关键词： Multiaccess communication Power control Propagation losses Frequency conversion direct-sequence code-division multiple access Analytical models Interference Base stations Degradation Frequency division multiaccess

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A new multiuser detection scheme for DS-CDMA systems

A new multiuser detection scheme for DS-CDMA systems

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MILCOM, Military Communications Conference

作者： S. Moshavi E.G. Kanterakis D.L. Schilling Electrical Engineering Department City College City University of New York New York NY USA SCS INFOCOM Inc. Sandspoint NY USA

direct sequence code division multiple access (DS-CDMA) systems have become a popular choice for use in cellular and personal communications. A new family of multistage low complexity linear receivers for DS-CDMA communications is introduced. The objective of the proposed design is to mitigate the effect of multiple access interference (MAI), the most significant limiting factor of user capacity in the conventional DS-CDMA channel. The receivers presented employ joint detection of multiple users, and therefore require knowledge of all the signature codes and their timing. Each stage of the underlying design recreates the overall modulation, noiseless channel, and demodulation process. The outputs of these stages are then linearly combined. The combining weights can be chosen to implement different linear detectors, including the decorrelating and minimum mean square error (MMSE) detectors. We focus on implementing the MMSE detector. Simulation results illustrate that significant performance gains can be achieved in both synchronous and asynchronous systems.

关键词： Multiuser detection Multiaccess communication Detectors multiple access interference direct-sequence code-division multiple access Timing Demodulation Decorrelation Mean square error methods Performance gain

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Effective interference: a novel approach for interference modelling and traffic analysis in CDMA cellular networks

Effective interference: a novel approach for interference mo...

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Proceedings of GLOBECOM '95

作者： J. Evans D. Everitt Department of Electiical and ElectIonic Engineering University of Melbourne Parkville VIC Australia

关键词： Cellular networks Mobile communication direct-sequence code-division multiple access Distribution functions Bandwidth Call admission control Interference constraints Telecommunication traffic Traffic control Stochastic processes

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