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Communications, IEE Proceedings-

Issue 6 • Date Dec 1996

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Displaying Results 1 - 10 of 10
  • Noncoherent detection with Viterbi decoding for GMSK signals

    Page(s): 373 - 379
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (704 KB)  

    Noncoherent detection with Viterbi decoding is proposed for the detection of GMSK signals in a Gaussian channel. Two detection techniques, limiter discriminator detection and differential phase detection, are considered with Viterbi decoding. The numerical results show that the proposed receivers with Viterbi decoding perform significantly better than the known receivers with feedback, and the improvement becomes more significant at narrower bandwidths View full abstract»

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  • Performance analysis of an output queueing ATM switch with heterogeneous traffic and multiple QoS

    Page(s): 356 - 362
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (648 KB)  

    The authors analyse an output queueing ATM switch which has the bandwidth-oriented priority (BOP) Markovian service scheme under the condition of heterogeneous traffic and multiple QoS. By designing the output queue service scheme in which heterogeneous traffic classes are separated by using separate buffers and the service to each buffer is done according to the BOP Markovian polling scheme, the server of an output queue is modelled as an independent geometric server (IGS) for each traffic class. This control method enables handling heterogeneous traffic, control of QoS and calculation of the equivalent bandwidth of each traffic to be independent. To find the equivalent bandwidth (EB) of a traffic class, the authors present an analysis which is based on the matrix-geometric analysis method. The output queue is modelled by multiple MMBBP/Geom/1/K queueing systems, one for each traffic class. Among several QoS parameters, the authors focus on the cell loss probability. The analysis is verified by simulation in measures of average queue length as well as cell loss probability. A connection admission control (CAC) method which calculates the EB of connections including a newly arriving cell by the iterative approach using the EB of the previous connection is also described View full abstract»

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  • Nonlinear dynamics in telecommunication systems: complex behaviour in nonlinear processing systems

    Page(s): 347 - 355
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    Nonlinear dynamic techniques are used to create a theoretical framework, from which the development, analysis and evaluation of a nonlinear model of a generalised switching element in a telecommunications network is investigated. The model represents the data flow through nonpreemptive multiprocess data processor systems found in communication nodes. A numerical solution to the model is presented, and is used in computer simulations to analyse the behaviour of both a single processing element and a multiprocessor array of switching nodes, in response to different input data streams. Presentation of resulting data is done using time domain and multidimensional phase space techniques which identify transitions between behaviour as the system parameter values are varied. A range of behaviour including stable, unstable chaotic and unbounded modes is identified, the impact on network performance is assessed View full abstract»

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  • Reliability-throughput: optimisation for adaptive forward error correction systems

    Page(s): 341 - 346
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (568 KB)  

    Adaptive error control systems are very efficient for digital transmission over time-varying channels. An adaptive forward error correction system based on code selection is considered. An estimation of the channel quality is utilised by the transmitter to adaptively encode the information bits to be sent over the channel. The proper code is selected to optimise the system performance in terms of the two most important evaluation measures: throughput and reliability. The optimisation technique is applied to the case of an adaptive system using BCH codes over Rayleigh fading channels. The achievement of the adaptive system over the non-adaptive system is studied in detail View full abstract»

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  • Cellular CDMA overlay systems

    Page(s): 389 - 395
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (652 KB)  

    In the past decade, there has been a considerable interest in spread spectrum techniques for applications that involve either code division multiple access (CDMA) or narrowband interference suppression. The CDMA network is considered to share a common spectrum with a strong narrowband microwave user. An interference suppression filter at each CDMA receiver is employed to reject the narrowband waveform. Gaussian approximation is assumed for the total interference, which includes fading interference, self interference, Gaussian noise, narrowband interference, multipath and multiple access interference View full abstract»

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  • Iterative interference cancellation for FFH/MFSK MA systems

    Page(s): 380 - 388
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    Iterative interference cancellation is introduced to improve the spectral efficiency in fast frequency hopping multiple access systems. The proposed algorithm iteratively cancels interference from users whose symbols have already been estimated. Both an interference-only channel and a frequency selective fading channel are considered. Noncoherently detected M-ary frequency shift keying is employed and all users are time-aligned at the receiver. Analytical results and results obtained from computer simulations are presented. It is shown that iterative interference cancellation may either substantially reduce the bit error probability or allow for a large increase in the number of simultaneously transmitting users View full abstract»

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  • Performance analysis of optical receivers with space diversity reception

    Page(s): 369 - 372
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (312 KB)  

    The performance of digital and analogue direct-detection optical receivers with space diversity reception is analysed. The cumulative probability distribution of the received signal is calculated for M-branch diversity and equal-gain combining receivers. For a given probability of detection, the permissible threshold detection level is shown to increase with the number of diversity branches. The improvement in carrier-to-noise ratio (CNR) is shown to be higher for selection diversity compared to combining diversity detection. Optimum diversity array spacing is calculated; this shows the practicality of space diversity systems. View full abstract»

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  • Performance, interarrival, and correlation analysis of four-phase MMPP model in ATM-based B-ISDN

    Page(s): 363 - 368
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (524 KB)  

    The MMPP has been used to model various B-ISDN sources, such as voice and video, as well as characterising the superposed traffic. It is able to capture the time-varying arrival rates and correlations between the interarrival times. This model is analytically tractable and produces accurate results. The matrix performance analysis of the continuous four-phase MMPP/D/1 queue proved that this queue is able to catch the possible characteristics of the video services as well as the voice and data services. The probability distribution function, the mean, and the squared coefficient of variation of the interarrival distribution are obtained. The correlation effect on the cell loss probability and waiting time at the four arrival rates and the four transition rates, is investigated. The analytical performance analysis of the queue is compared with the simulation results View full abstract»

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  • Optimal blocked random access algorithm for CDMA-random access systems

    Page(s): 396 - 400
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (500 KB)  

    Code-division multiple-access-random access systems are considered. Specifically, the authors consider a generalised common receiver model with transmitter-based code assignment and study a class of random access algorithms known as blocked random access algorithms. It is assumed that the number of active users at the beginning of a collision resolution epoch is known. An appropriate state of the system and control variables that constitute a Markovian decision process (MDP) are identified aid it is shown that the problem of optimal collision resolution algorithm is equivalent to the first passage problem of this MDP. The optimal control actions specify the number of users to be enabled separately for each code. The algorithm is illustrated with numerical examples View full abstract»

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  • Index

    Page(s): 401 - 404
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (324 KB)  

    First Page of the Article
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