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IEE Proceedings I (Communications, Speech and Vision)

Volume 136, Issue 5, October 1989

Volumes & issues:

Volume 136, Issue 5

October 1989

Objective speech distortion measures and their relevance to speech quality assessments
  • Author(s): S. Dimolitsas
  • Source: IEE Proceedings I (Communications, Speech and Vision), Volume 136, Issue 5, p. 317 –324
  • DOI:  10.1049/ip-i-2.1989.0045
  • Type: Article
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  • p. 317 –324 (8)
    The paper presents a review of several commonly employed objective speech distortion measures and their relevance to subjective assessments of speech quality. Since many of the objective measures described in the paper have been covered previously in other reviews, we have concentrated primarily on three aspects. First, the philosophy of progressively constructing objective distortion measures in order to incrementally improve their capability to predict subjective quality (typically done at the expense of computational complexity). Secondly, we have concentrated on the use of objective measures as complementary tools to subjective evaluations, and thirdly, on the methods for evaluating the relative performance of different objective measures.
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Erratum: Dynamic planning model for urban telephone networks and its applications
Classified vector excitation speech coding
  • Author(s): S. Marlow  and  B. Buggy
  • Source: IEE Proceedings I (Communications, Speech and Vision), Volume 136, Issue 5, p. 325 –327
  • DOI:  10.1049/ip-i-2.1989.0047
  • Type: Article
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  • p. 325 –327 (3)
    Code excited linear prediction (CELP) has been shown [1] to be capable of achieving high quality speech compression at very low bit rates. However, the original method suffers from the two drawbacks that it requires a large amount of computation, and the Gaussian codebook used is not able to reproduce a sharp impulse in the coded residual waveform. The authors present a classified vector excitation coding (CVXC) scheme based on selective modelling of the LPC residual which attempts to overcome both these drawbacks by using separate codebooks for separate excitation types. A further feature of our coder which helps preserve the nature of pulsive residuals, is the use of pairwise nearest neighbour (PNN) matching [2] to generate the excitation codebooks.
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Impact of non-Gaussian noise on the performance of M-ary CPSK signalling transmitted through two-link nonlinear channels
Pseudo error rate of a PSK system with hardware imperfections, noise and cochannel interference
  • Author(s): I.M. Kostić
  • Source: IEE Proceedings I (Communications, Speech and Vision), Volume 136, Issue 5, p. 333 –338
  • DOI:  10.1049/ip-i-2.1989.0049
  • Type: Article
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  • p. 333 –338 (6)
    One of the problems that arise in the course of designing a pseudo error monitor (PEM) is the necessity of knowing the relationship between the pseudo error rate (Ppe) and the actual error rate (Pe) in the presence of channel impairments. In the paper, the problem is solved analytically for a fairly general system model. A unified analysis of the Ppe and the Pe of an M-ary CPSK hard limited multilink system with some hardware imperfections, Gaussian noise and cochannel interference per link, is presented. Extensions of the analysis on M-ary DPSK signals and/or on a linear multilink system are discussed, too.Several types of modern PSK communication systems may be seen as special cases of the model considered in this paper, for example, radio relay link and satellite two-link system.It is shown that knowledge of the asymptotic behaviour of the probabilities Ppe and Pe is very useful for PEM design. To illustrate this, details are given for a one-link quaternary CPSK system.
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Erratum: Study of adjacent channel AM interference suppression
Priority oriented channel access for cellular systems serving vehicular and portable radio telephones
  • Author(s): D. Hong  and  S.S. Rappaport
  • Source: IEE Proceedings I (Communications, Speech and Vision), Volume 136, Issue 5, p. 339 –346
  • DOI:  10.1049/ip-i-2.1989.0051
  • Type: Article
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  • p. 339 –346 (8)
    A priority oriented channel access scheme for cellular mobile radio telephone systems serving vehicular and portable radio telephone users is described. The calls generated are divided into three different classes: new vehicular calls, new portable calls and hand-off calls. Priority is given to hand-off calls over new calls and to vehicular calls over portable calls. Appropriate analytical models and criteria are developed and used to derive performance characteristics. Blocking and forced termination probabilities for each kind of user are determined as functions of system parameters. Noncompleted call probability is defined as a useful performance measure for each kind of user. The effects of priorities and hand-off procedures on performance characteristics are investigated. General formulas are given and specific numerical results for nominal system parameters are presented.
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Effects of selection diversity on error performance of digital mobile radio systems
  • Author(s): M.M. Pejanović ; J.A. Edwards ; I.S. Stojanović
  • Source: IEE Proceedings I (Communications, Speech and Vision), Volume 136, Issue 5, p. 347 –350
  • DOI:  10.1049/ip-i-2.1989.0052
  • Type: Article
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  • p. 347 –350 (4)
    The effect of selection diversity reception on the error performance of the digital mobile radio systems is investigated. The binary frequency shift keying system (FSK) using noncoherent (NC) demodulation, with a limiter/discriminator receiver is considered. All major error causing factors, fading and Gaussian and impulsive noise, are taken into account. The corresponding general expression for the error probability (BER) is derived. This expression is used to analyse the improvements in the BER performance of the considered system gained by the M-branch selection diversity technique.
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Carrier-phase synchronisation in the demodulation of UQPSK signals
  • Author(s): A.P. Clark  and  A. Aftelak
  • Source: IEE Proceedings I (Communications, Speech and Vision), Volume 136, Issue 5, p. 351 –360
  • DOI:  10.1049/ip-i-2.1989.0053
  • Type: Article
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  • p. 351 –360 (10)
    The paper describes a novel carrierphase synchronisation process that has been developed for use in a digital communication system operating over a satellite link and employing unbalanced quaternary phase shift keyed (UQPSK) signals. The satellite is not geostationary and may travel close to the surface of the earth over at least a part of its orbit. Correct carrier phase synchronisation needs to be achieved here as soon as the satellite rises above the horizon, during the time it is transmitting data signals, and therefore without the use of a known training signal. Under these conditions the digital signal is received at a low signal to noise ratio and in the presence of a severe Doppler shift. Correct carrier phase synchronisation must then be maintained as the satellite passes overhead and until it approaches the horizon again. Thus the synchronisation circuits must tolerate also a high rate of change of Doppler shift, albeit at a higher signal to noise ratio.The synchronisation algorithm is in two separate parts that operate sequentially and are both non-data aided. The first part removes the Doppler shift from the received signal and the second part then achieves carrier phase synchronisation, which is maintained over the rest of the transmission.The paper describes the new algorithms and presents the results of a series of computer simulation tests to assess their performances.
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GMSK with limiter discriminator integrator detection in satellite mobile channel
  • Author(s): I. Korn
  • Source: IEE Proceedings I (Communications, Speech and Vision), Volume 136, Issue 5, p. 361 –366
  • DOI:  10.1049/ip-i-2.1989.0054
  • Type: Article
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  • p. 361 –366 (6)
    The author derives a formula for the error probability of partial response frequency shift keying with limiter discriminator integrator detector with and without decision feedback for the satellite mobile channel which contains as special cases the Gaussian channel and the land mobile channel. The author applies the formulae to Gaussian minimum shift keying and compute the error probability as a function of energy to noise ratio and other system parameters (Doppler frequency, maximum Doppler frequency, bandwidth of Gaussian filter and ratio of power in the direct and diffuse signal components).
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