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Communications, IEE Proceedings-

Issue 5 • Date Oct 1997

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Displaying Results 1 - 12 of 12
  • Cycle-slipping probability of first-order phase-locked loop using transient analysis

    Publication Year: 1997 , Page(s): 357 - 360
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (376 KB)  

    The first-order phase-locked loop is a standard feedback device commonly used to provide both carrier and clock synchronisation in digital transmission systems. At low signal-to-noise ratios increased jitter on the timing estimates results in a raised probability of symbol error and an increased likelihood of synchroniser symbol slips; in the latter case, symbols are either deleted from or inserted into the received data stream. The paper re-examines the full transient modulo-2π and nonmodulo-2π phase error process and demonstrates that the probability of cycle-slipping with time can be expressed in terms of the loop cycle-slipping frequency as determined from a previous stationary analysis of the loop View full abstract»

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  • Modelling multimedia traffic over ATM using MMBP

    Publication Year: 1997 , Page(s): 307 - 310
    Cited by:  Papers (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (312 KB)  

    The Markov-modulated Bernoulli process (MMBP) is widely used in modelling traffic sources. The authors propose a so-called high-low (H/L) model, a two-state Markov chain, to characterise multimedia traffic on ATM-based broadband networks. The H/L model has two nonzero-valued states corresponding to the high-activity and the low-activity level of multimedia traffic. The queue-length distribution of an ATM switch fed with N identical MMBP sources was derived using a probability generating function coupled with a matrix geometric approach. By decomposing matrices into their spectral representation forms the queue length can be evaluated by considering the roots of its characteristic function. Numerical results for the case of two MMBPs are also presented View full abstract»

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  • Performance analysis of delay-loss priority mechanism using Markov modulated arrival stream

    Publication Year: 1997 , Page(s): 311 - 315
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (524 KB)  

    The authors propose a new mechanism to handle the delay and loss requirements of ATM traffic simultaneously. It is designed to satisfy the different levels of cell-loss performance for two classes of heterogeneous nonreal-time ATM traffic as well as the delay and loss requirements of real-time traffic simultaneously. The cell arrivals of the input streams are modelled by the MMPP. Both a real-time buffer and a nonreal-time buffer are served by a common server. The buffer occupancies of each traffic type are controlled by the partial buffer sharing scheme. The steady-state probabilities of the queue-length distributions are obtained using the stochastic integral approach View full abstract»

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  • Loss periods in ATM output multiplexer

    Publication Year: 1997 , Page(s): 301 - 306
    Cited by:  Papers (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (504 KB)  

    The authors present a new approach to evaluating the loss periods in the output multiplexer of an ATM switch. First, they present a model for the output multiplexer using a discrete time finite capacity queueing system model with a threshold in the queue and priority in the bursty incoming cells. In modelling the loss period, they divide the queue space into a nonloss region, a half-loss region and a full-loss region, and define their corresponding time periods as the nonloss period, half-loss period and full-loss period, respectively. Next, they derive a general formula for the mean sojourn time for which a queue stays in a region. They derive formulae for the loss period, cell loss rate due to buffer overflow, discard rate for low priority cell and cell waiting time. Finally, they present the results of numerical experiments View full abstract»

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  • Computer model for analysing digital magnetic recording systems

    Publication Year: 1997 , Page(s): 289 - 294
    Cited by:  Patents (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (544 KB)  

    A simple model is developed for the recording performance of a complete digital magnetic recording system using peak detection and an instrumentation tape recorder operating in the low/mid speed range of its capabilities. Results obtained using this model are compared with a wide variety of experimental data. Studies are made of channel and equaliser output pulses and also probability of error as a function of record current amplitude, packing density and replay equaliser parameters. Predictions are found to be of acceptable accuracy and justify the use of this type of modelling as a tool in recording system design View full abstract»

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  • Performance improvement of fibre-optic code-division multiple-access systems by using error-correction codes

    Publication Year: 1997 , Page(s): 316 - 321
    Cited by:  Papers (5)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (560 KB)  

    In code-division multiple-access (CDMA) systems using all-optical signal processing, the optical multiple-access interference (OMAI) degrades the system performance and can ultimately limit the number of active users. To reduce the effect of OMAI, error-correction codes are used in both asynchronous and synchronous fibre-optic CDMA systems. It is shown that the use of asymmetric error-correction binary block codes can not only effectively reduce the bit-error rate, but also increase the maximum number of active users in a constant-bandwidth network more efficiently than using symmetric error-correction binary block codes. Therefore, this permits implementation of a cost-effective fibre-optic CDMA network View full abstract»

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  • Analysis and design of survivable telecommunications networks

    Publication Year: 1997 , Page(s): 322 - 330
    Cited by:  Papers (5)  |  Patents (5)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (948 KB)  

    The analysis and design of mesh restorable and self-healing ring networks is considered. A general class of traffic-based survivability measures to analyse telecommunications networks is proposed. These measures calculate the average traffic-carrying capability of a network over all possible failure states. Traffic-based survivability measures are proposed to analyse mesh networks with and without restoration scheme. For the design of mesh restorable networks the network configuration and working capacity assignment are combined to minimise the cost before restoration is added into the network. Path restoration in spare capacity assignment is considered. A joint approach that combines configuration, working and spare capacity assignments altogether is addressed. A new architecture is proposed called the dual-homing hierarchical self-healing ring (DH-HSHR) architecture to interconnect self-healing rings. A heuristic algorithm for single-homing HSHRs is modified to find near optimum DH-HSHR configurations. Numerical results are given and the two restoration strategies, mesh and ring, compared in terms of survivability and cost View full abstract»

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  • Access flow control scheme for ATM networks using neural-network-based traffic prediction

    Publication Year: 1997 , Page(s): 295 - 300
    Cited by:  Papers (5)  |  Patents (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (572 KB)  

    The authors propose a new approach to the problem of congestion control arising at the user network interface (UNI) of ATM-based broadband networks. The access flow control mechanism operates on the principle of feedback control. It uses a finite impulse response (FIR) neural network to accurately predict the traffic arrival patterns. The predicted output in conjunction with the current queue information of the buffer can be used as a measure of congestion. When the congestion level is reached, a control signal is generated to throttle the input arrival rate. The FIR multilayer perceptron model and its training algorithm are discussed. Simulation results presented in the paper suggest that the scheme provides a simple and efficient traffic management for ATM networks View full abstract»

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  • Distortion effects of multicarrier envelope limiting

    Publication Year: 1997 , Page(s): 349 - 356
    Cited by:  Papers (3)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (708 KB)  

    The feasibility of reducing the peak power rating of a multichannel amplifier by limiting the peak-to-mean ratio of its input signal is examined in terms of the resulting intermodulation distortion levels. A number of current modulation schemes are examined and the effects of limiting are highlighted in each case, In addition, both ideal and practical limiter characteristics are assessed and the differences illustrated. These results indicate that a controlled amount of limiting is permissible in many cases, while still ensuring that the overall system specifications are met. This leads to considerable benefits in terms of power and cost savings in the design of a base station or satellite transmitter View full abstract»

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  • New multiuser detector for asynchronous CDMA

    Publication Year: 1997 , Page(s): 336 - 340
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (432 KB)  

    A novel multiuser detector for asynchronous code division multiple access (CDMA) system is presented. Using a new type of spreading sequences and shortened correlators with linear combining, an unbiased one-shot suboptimum detection is achieved without increasing the receiver complexity. Two decorrelating algorithms, the direct and the recursive methods, are given for the proposed detector configuration. Theoretical and simulation results show that the receiver performs well in severe near-far environments View full abstract»

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  • Engineering of a CDMA radio uplink for a mobile radio demonstration system

    Publication Year: 1997 , Page(s): 341 - 348
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (996 KB)  

    A CDMA mobile radio demonstration system has been created by a joint industry/university project in the UK. The paper describes the engineering of the reverse link (from mobile to base station). The link hardware is described. The main features of interest are the power mechanism and the all-digital RAKE receiver. Results presented illustrate the BER performance over a multipath channel simulator and the power control mechanism performance View full abstract»

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  • Markov analysis of multichannel star-connected network with channel sensing and collision detection

    Publication Year: 1997 , Page(s): 331 - 335
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (392 KB)  

    When many stations need to communicate with a central server, the simplest way to allow them to transmit messages to the server is to use a non-centralised contention access protocol. One of the most efficient of these protocols is channel sense multiple access with collision detection (CSMA/CD). Exact analyses of single-channel CSMA/CD networks have been done, but, so far, all the analyses of multichannel CSMA/CD networks in the literature have used approximations to simplify the process of finding the transition matrix. The paper presents an exact Markov analysis of a multichannel CSMA/CD network. It is shown that such a multichannel system performs better than an equivalent network having just one channel View full abstract»

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