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Communications Letters, IEEE

Issue 10 • Date Oct. 1998

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Displaying Results 1 - 9 of 9
  • On the channel capacity of the residential power circuit used as a digital communications medium

    Page(s): 267 - 268
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (83 KB)  

    Based on the results of an extensive measurement campaign executed in the city of Amsterdam, the Netherlands, a channel model for the residential power line channel (RPLC) used as a digital communications channel is presented. From this model bounds for the channel capacity of such a channel used under European regulations are calculated. It is concluded that it is indeed theoretically possible to use the RPLC to solve the local loop problem in a second, fixed line telephone network. View full abstract»

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  • Merit factor based comparison of new polyphase sequences

    Page(s): 269 - 270
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (60 KB)  

    New polyphase sequences, named Px sequences, of a square integer length are found. Standard merit factors of polyphase Frank (1963), P1, P3, P4, Golomb and Chu (1972) sequences are compared with merit factors of Px sequences. It is found that Px sequences have better sidelobe-energy merit factor and not worse maximum-sidelobe merit factor in comparison to all mentioned analytically constructed sequences. View full abstract»

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  • A new formula for MDPSK symbol error probability

    Page(s): 271 - 272
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (79 KB)  

    This article presents an extremely compact new formula for the symbol error probability in M-ary differential phase shift keying (MDPSK) that is extraordinarily similar to its counterpart for M-ary phase shift keying (MPSK). This result follows from a new form for a generic error probability associated with the phase angle between two vectors perturbed by Gaussian noise. The new form also leads to a new expression for the Marcum Q-function. As special cases, the generic error probability is noted to also contain MPSK, CPFSK, and digital FM. Finally, it is pointed out that the generic error probability simplifies the error probability expressions in other situations such as nonorthogonal signaling, maximum-likelihood differential detection of DPSK with block-by-block detection, and Gray coding of MDPSK. View full abstract»

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  • Power control at the combiner output to maximize the uplink capacity on a cellular spread spectrum system

    Page(s): 273 - 275
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (66 KB)  

    The benefits of applying maximal ratio combining instead of selection combining when using macrodiversity in a cellular code-division multiple access (CDMA) system were studied. In particular, using maximal ratio combining with power control made at the combiner output, and assuming equal interference at every base station, we provide a simple proof to show that we can achieve on the uplink the same capacity per cell as with an isolated cell. On extending the study to a practical case with a limited number of cells in macrodiversity in comparison with the unrestricted theoretical case, we found that the results on cell capacity with maximal ratio combining were quite close to the results with an isolated cell. View full abstract»

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  • Generation of two equal power correlated Rayleigh fading envelopes

    Page(s): 276 - 278
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (86 KB)  

    A procedure for generating two equal power Rayleigh-fading envelopes with any desired cross-correlation coefficient is given. Having this ability will aid researchers in simulating correlated fading envelopes, which can be used to study the impact of correlation on the performance of diversity systems. View full abstract»

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  • Bounds on the symmetric cutoff rate for QAM transmissions over time-correlated flat-faded channels

    Page(s): 279 - 281
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (125 KB)  

    This article presents new upper and lower bounds on the symmetric cutoff rate for block-coded quadrature-amplitude-modulated (QAM) signaling over links affected by time-correlated Rayleigh-distributed flat-faded phenomena. The proposed bounds assume maximum-likelihood soft-decoding with perfect channel-state-information at the receiving side and hold for any form of QAM constellations. These bounds are quickly computable and constitute an efficient means to estimate the cutoff rate of systems employing very long codewords, so that an exact evaluation of the cutoff rate results. Analytical and numerical evidence of the tightness of the presented bounds is also provided. View full abstract»

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  • Near optimal detection of signals in impulsive noise modeled with a symmetric /spl alpha/-stable distribution

    Page(s): 282 - 284
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (89 KB)  

    There has been great interest in symmetric /spl alpha/-stable distributions which have proved to be very good models for impulsive noise. However, most of the classical non-Gaussian receiver design techniques cannot be extended to the symmetric /spl alpha/-stable noise case since these techniques require an explicit compact analytical form for the probability density function (PDF) of the noise distribution which /spl alpha/-stable distributions do not possess. A new analytical representation has been suggested for the symmetric /spl alpha/-stable PDF which is based on scale mixtures of Gaussians. Based on this new analytical representation, this paper introduces a novel near-optimal receiver for the detection of signals in symmetric /spl alpha/-stable noise. The performance of the new receiver is very close to the locally optimum receiver and is significantly better than the performance of previously suggested sub-optimum receivers. The new technique has important potential in radar, sonar, and other applications. View full abstract»

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  • Image transmission in multicore-fiber code-division multiple-access networks

    Page(s): 285 - 287
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (107 KB)  

    Two-dimensional (2-D) signature patterns, so-called optical orthogonal signature pattern codes (OOSPCs), were previously proposed to encode binary digitized image pixels in optical code-division multiple-access (CDMA) networks with "multicore" fiber. The new technology enables parallel transmission and simultaneous access of 2-D images in a multiple-access environment. However, previous work on OOSPCs assumed that the weight of every signature pattern in a code set was the same. In this paper, we construct and analyze a new family of OOSPCs without this assumption. Since the performance of a signature pattern varies with its code weight, our approach is useful for optical CDMA networks with a multiple performance requirement. View full abstract»

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  • Balancing workload and recovery load on distributed fault-tolerant VOD systems

    Page(s): 288 - 290
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (70 KB)  

    This letter presents a new code sequence for dispatching playback jobs among distributed video-on-demand servers. The dispatch accordingly has the property of evenly distributing workload among all servers and balancing recovery load on surviving servers if one of the servers fails. We give an O((n-1)!) algorithm for efficiently finding a dispatch sequence for n servers. View full abstract»

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IEEE Communications Letters  is aimed at satisfying the need for rapid dissemination of information, offering a vehicle for authors to expose their results to be used in future developments. This ensures early recognition of work. 

 

 

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Editor-in-Chief
George K. Karagiannidis
Aristotle University of Thessaloniki
Greece