IEE Colloquium Adaptive Signal Processing for Mobile Communication Systems (Ref. No. 1997/383)

29 Oct 1997

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Displaying Results 1 - 15 of 15
  • Adaptive receiver structures for underwater acoustic communications

    Publication Year: 1997, Page(s):11/1 - 11/6
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (404 KB)

    An adaptive array receiver structure for underwater acoustic telemetry links is presented. The use of array processing methods is necessary in order to mitigate the effect of multipath propagation in underwater channels. The paper shows how shallow short range (2 km) and deep long range (50 km) channels can benefit from the same array structure, yet with the processing gain achieved in a different... View full abstract»

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  • An integrated solution for ambient noise reduction in telecommunication applications

    Publication Year: 1997, Page(s):6/1 - 6/7
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (464 KB)

    This paper describes an integrated solution for digital ambient noise reduction (ANR) for use in telecommunication ear-pieces. It concentrates on the issue of ambient noise reduction at an ear-piece for improved intelligibility of the received voice signal. An overview of background noise issues is presented highlighting the suitability of active noise control techniques as a reduction mechanism. ... View full abstract»

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  • Optimised MSE and delay for blind equalizers

    Publication Year: 1997, Page(s):10/1 - 10/5
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (256 KB)

    Multipath Rayleigh fading channels which have fast time variation can cause loss of tracking in equalizers, from which recovery without retraining is extremely difficult. In such situations, blind techniques which recover the optimum MSE over all possible symbol delays can be helpful. This paper explores one such technique. Simulation results demonstrate its suitability View full abstract»

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  • Bayesian blind deconvolution for mobile communications

    Publication Year: 1997, Page(s):9/1 - 9/6
    Cited by:  Papers (5)
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (368 KB)

    This paper discusses the problem of restoring a digital input signal which has been degraded by an unknown FIR filter in additive Gaussian noise. A Bayesian approach is taken to recover the signal, implemented by the Gibbs sampler, a Markov chain Monte Carlo method. A method for drawing a random sample of a sequence of bits is presented. This is shown to have a faster convergence and better perfor... View full abstract»

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  • Adaptive mobile channel prediction for decision directed RAKE receivers

    Publication Year: 1997, Page(s):13/1 - 13/5
    Cited by:  Papers (1)
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (380 KB)

    The authors describe a robust channel prediction technique for a direct sequence spread spectrum (DS-SS) code division multiple access (CDMA) system in a fast fading environment. For improved performance the RAKE filter taps are coherently combined, hence accurate channel estimation is required. A FIR type linear prediction filter for each RAKE filter tap is used to estimate the impulse response. ... View full abstract»

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  • A subband adaptive filter

    Publication Year: 1997, Page(s):1/1 - 1/6
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (428 KB)

    A new real-valued oversampled filter bank has been proposed which reduces the “inband” alias. The filter bank consists of at least three channels which are subsampled by different subsampling ratios. We investigate the applicability of this filter bank for adaptive subband filtering and compare the setup with existing subband and fullband techniques View full abstract»

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  • On-line tracking for blind source separation using zero-point probability

    Publication Year: 1997, Page(s):14/1 - 14/5
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (264 KB)

    We have developed a novel on-line method for separating instantaneous, linear mixtures of super-Gaussian sources. The method uses a simple, constantly updating estimate of the central part of the probability distributions of the candidate mixed signals which can then be used to update the unmixing coefficients. The method is simple to implement and its concentration on the central part of the prob... View full abstract»

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  • Efficient subband adaptive filtering with oversampled GDFT filter banks

    Publication Year: 1997, Page(s):4/1 - 4/9
    Cited by:  Papers (2)  |  Patents (5)
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (608 KB)

    This paper addresses the numerical efficiency of adaptive filtering implemented in subbands. Our approach first focuses on oversampled GDFT (generalized DFT) filter banks and their potential benefits over other possible subband decompositions. Although the subband filters presented use complex arithmetic, the discussed method allows factorization into a real valued polyphase network, followed by a... View full abstract»

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  • Blind estimation of FIR communication channels via probabilistic methods

    Publication Year: 1997, Page(s):8/1 - 8/6
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (392 KB)

    In this paper a new blind estimation method for FIR channels is presented. The transmitted signal under consideration is multilevel PAM. The method uses the information contained in the conditional probability density functions of the received signal samples. Simulation results show that the method works well for low SNRs and short record lengths. The price to pay is the high complexity View full abstract»

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  • A robust echo cancellation system especially suited for wireless car handsfree environment

    Publication Year: 1997, Page(s):3/1 - 3/6
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (252 KB)

    In wireless car handsfree communications, the far-end speech is played by the speaker, reflected inside the car cockpit and collected by the microphone. Therefore, the far-end voice is sent back to the far-end talker, who will hear his own voice, with a delay due to the wireless transmission delay, typically in the range of 200 ms. In the car environment, an other challenging part is the detection... View full abstract»

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  • IEE Colloquium on Adaptive Signal Processing for Mobile Communication Systems (Ref. No.1997/383)

    Publication Year: 1997
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (52 KB)

    The following topics were dealt with: subband adaptive filter; stability of NLMS with zero-phase signal conditioning for acoustic echo cancellation; echo cancellation system for wireless car handsfree environment; subband adaptive filtering with oversampled GDFT filter banks; multi-sensor subband adaptive noise cancellation for speech enhancement; ambient noise reduction in telecommunication appli... View full abstract»

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  • Multi-sensor sub-band adaptive noise cancellation for speech enhancement in an automobile environment

    Publication Year: 1997, Page(s):5/1 - 5/7
    Cited by:  Papers (1)  |  Patents (1)
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (548 KB)

    Concerning noise in automobiles, the effect of spacing sub-bands nonlinearly in a multi-microphone sub-band adaptive (MMSBA) speech enhancement system as in humans according to a published cochlear function (Greenwood, 1990) is investigated, and the MMSBA scheme is further developed by employing diverse sub-band processing (SEP) in order to allow inter-channel features within the sub-bands to infl... View full abstract»

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  • A novel non-linear adaptive structure for time variant equalisation

    Publication Year: 1997, Page(s):7/1 - 7/6
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (392 KB)

    A considerable effort has been devoted to research into adaptive equalisers. This research has been dominated by the needs of either cable or fixed radio links. Such communications links have two key characteristics of relevance to the topic of this paper: (i) the exact characteristic (transfer function) of the channel is a-priori unknown. (ii) The channel is essentially time invariant, or at leas... View full abstract»

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  • Stability of NLMS with zero-phase signal conditioning for acoustic echo cancellation

    Publication Year: 1997, Page(s):2/1 - 2/4
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (284 KB)

    A problem with hands-free telephones is that the far-end talker experiences an echo of his/her own speech because of acoustic coupling between the microphone and speaker caused by their co-location in a reverberant enclosure such as a car cabin. The echo can be eliminated by using an acoustic echo canceller (AEC). The most popular adaptive filter for AEC is the normalised least-mean squares (NLMS)... View full abstract»

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  • Blind equalization-combinations of Bussgang- and higher-order-statistics-based methods

    Publication Year: 1997, Page(s):12/1 - 12/6
    Cited by:  Papers (2)
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (320 KB)

    A new generation of higher-order-statistics (HOS) based blind equalization techniques, like the eigenvector algorithm (EVA) published in 1997 by B. Jelonnek, D. Boss and K.-D. Kammeyer, leads to a much better performance. In this paper these techniques are used to initialize a conventionally Bussgang algorithm. The purpose is to show, through simulations, that combinations of both techniques have ... View full abstract»

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