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Communications, IEEE Transactions on

Issue 1 • Date Jan 1995

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Displaying Results 1 - 18 of 18
  • Optimized signaling waveforms to reduce the effects of intersymbol interference and timing jitter

    Publication Year: 1995 , Page(s): 11 - 14
    Cited by:  Papers (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (260 KB)  

    The mainlobe energy of a member from the class of symbol waveforms with null derivatives at zero crossings is maximized. Thus, a bandlimited pulse shape without intersymbol interference, robust against jitter and timing errors, is obtained. Comparisons to known pulses show advantages for these signals at the expense of bandwidth, which linearly increases with the number of null derivatives View full abstract»

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  • Matched median filter for detecting QAM signals

    Publication Year: 1995 , Page(s): 7 - 10
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (276 KB)  

    In this paper, the complex matched median filter (MMF) is developed for QAM signal detection. It is shown that the MMF is robust against impulsive type noise. By combining the MMF and the linear matched filter (LMF), an extended class of matched filters is introduced. These filters combine the desirable properties of MMF and LMF and behave well in varying noise environments. Computer simulations demonstrate that the proposed detectors give a much smaller symbol error probability than the LMF when the noise has an impulsive component and produces only a slight performance degradation in the case of pure Gaussian noise View full abstract»

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  • Analysis and comparison of hot-potato and single-buffer deflection routing in very high bit rate optical mesh networks

    Publication Year: 1995 , Page(s): 88 - 98
    Cited by:  Papers (63)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (964 KB)  

    The steady state behavior of regular two-connected multihop networks in uniform traffic under a hot-potato and a simple single-buffer deflection routing technique is analyzed for very high bit rate optical applications. Manhattan Street Network and ShuffleNet are compared in terms of throughput, delay, deflection probability, and hop distribution both analytically and by simulation. It is analytically verified that this single-buffer deflection routing technique recovers in both networks more than 60% of the throughput loss of hot-potato with respect to store-and-forward when packets are generated with independent destinations. This gain, however, decreases to below 40% when the average message length exceeds 20 packets View full abstract»

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  • The probability density of intersymbol interference for trellis-coded modulation

    Publication Year: 1995 , Page(s): 44 - 51
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (576 KB)  

    Knowledge of the probability density function (pdf) of intersymbol interference (ISI) can be used in the computation of system error probabilities and to help identify the cause of the errors. Exact computation of the probability density is only practicable in a few special cases. Several algorithms exist for computing approximate pdfs of ISI but these only work with certain signal constellations and transmitted symbols that are mutually independent or coded by partial response. This paper considers an algorithm for the computation of ISI pdfs for trellis-coded modulation with general 1D and 2D constellations. The results suggest that symbol dependencies introduced into the transmitted signal by symmetric trellis-codes have negligible effect on the pdf of the ISI. Although the ideas presented are general in nature, examples are given for ISI pdfs on a line-of-sight radio channel View full abstract»

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  • A novel approach to estimating the cell loss probability in an ATM multiplexer loaded with homogeneous on-off sources

    Publication Year: 1995 , Page(s): 117 - 126
    Cited by:  Papers (24)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (860 KB)  

    Estimating the cell loss probability in an ATM multiplexer is one of the most important problems concerning congestion control and bandwidth management in an ATM-based BISDN. We propose a new approach to estimating the cell loss probability in an ATM multiplexer. We use the Markov modulated deterministic process (MMDP) to approximate the actual arrival process and then model the ATM multiplexer as an MMDP/D/1/K queueing system. Using queueing analysis, we derive a formula for the cell loss probability expressed in terms of the limiting probabilities of a Markov chain. We propose two approximation methods based on the results of the analysis. The actual arrival process is approximated by an (M+1)-state MMDP in the first method and by a two-state MMDP in the second. The major advantages of both methods are simplicity, computational efficiency, and numerical stability. The most attractive feature of the second method is that the cell loss probability can be expressed in closed form. Numerical and simulation results show that the first method is sufficiently accurate for all cases in which burst-level congestion is the main contributing factor to cell loss, while the closed-form formula is sufficiently accurate for applications where the average burst length is large (such as large file transfers, image retrievals, etc.) View full abstract»

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  • Design and performance analysis of an advanced, narrowband integrated voice/data mobile radio system

    Publication Year: 1995 , Page(s): 107 - 116
    Cited by:  Papers (3)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (940 KB)  

    Private land mobile communications have experienced significant demand for increased capacity and for new services, but congestion within the currently allocated 450 and 800 MHz bands has severely limited the capability of present generation systems to meet this demand. This paper proposes a narrowband integrated voice/data mobile radio system which triples current voice traffic capacity and simultaneously provides capacity for mobile data communications such as mobile data terminals, automatic vehicle location, and mobile facsimile by utilizing the silence gaps inherent in speech. The system is designed to fit within the narrowband 25 kHz channels in the 450 and 800 MHz frequency bands, and thus the system can replace existing private land mobile radio systems with minimum impact. The centerpiece of the system design is an evolutionary multiplexing and access control technique known as Packetized Data, Voice Dedicated (PDVD) Burst Switching which allows transmission of data within the silence gaps inherent in speech. Simulation results for various voice and data traffic loads show the flexibility and efficiency of the proposed narrowband integrated voice/data mobile radio system View full abstract»

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  • A new M-ary wideband communication system with application to multipath channels-Part I: system performance

    Publication Year: 1995 , Page(s): 127 - 135
    Cited by:  Papers (3)  |  Patents (23)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (640 KB)  

    We present a new M-ary wideband communication system based on use of binary spread-spectrum sequences and a correlation receiver. The proposed system offers a significant savings in receiver complexity compared to classical M-ary systems as only one correlator is required and also the word synchronization can be automatically made. The sequences used here were primarily described by Yates and Holgate (1979) and generalized by Potter (1980). A set of Yates-Holgate (Y-H) sequences is constructed from a single m-sequence called the “parent”. When any sequence in the set is cross correlated with the “parent”, the obtained cross-correlation function (CCF) has a shape that simply and uniquely identifies that sequence-in the same time it defines the word synchronization. The transmitter associates k information bits to a sequence of N chips selected in a Y-H set of M=2 k sequences. The receiver correlates the received sequence with the parent and hence can decide what sequence has been transmitted. In this way, the receiver can recover the k information bits. In this paper (Part I of two), we present the performance of this system in a nonfading channel with additive white Gaussian noise and in some multipath channels View full abstract»

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  • Fixed- and movable-boundary channel-access schemes for integrated voice/data wireless networks

    Publication Year: 1995 , Page(s): 64 - 74
    Cited by:  Papers (37)  |  Patents (8)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1000 KB)  

    Addresses the major issues associated with channel access in integrated wireless networks, and proposes and analyzes the “wireless integrated multiple access” (WIMA) protocol. This scheme is based on a mixture of boundary ideas for integration and of previously introduced protocols for wireless access, and is well suited to either satellite or to terrestrial networks. A two-dimensional first-order Markov chain model for this scheme is presented, and techniques that exploit the structural properties of this chain to simplify the evaluation of the equilibrium state, without sacrificing accuracy, are described. Analytical models for the evaluation of data-packet delay for both fixed- and movable-boundary versions of this protocol and for voice-call blocking probability are presented. Performance results illustrate the dependence of performance on system parameters, and demonstrate the improved performance that can be achieved through the use of the movable-boundary version View full abstract»

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  • Optimal system parameters choice in HF FSK radio links

    Publication Year: 1995 , Page(s): 15 - 18
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (324 KB)  

    The paper deals with the optimal choice of the system parameters in an HF digital radio link employing 2 FSK modulation and limiter/discriminator demodulation. Using a simulation approach for short time performance evaluation it is shown that, for this type of system, the optimal choice is not the same as in the case of the ideal channel and is independent of the SNR value at receiver point. The effect of the filters' shape is also analyzed, showing that the best performance is obtained somewhere in the middle between very steep filtering and Gaussian-like transfer function behaviors View full abstract»

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  • Use of delegated tuning and forwarding in wavelength division multiple access networks

    Publication Year: 1995 , Page(s): 52 - 63
    Cited by:  Patents (15)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1216 KB)  

    Proposes delegated tuning and forwarding (DTF), a new architecture for dynamically assigning wavelength channels in a “broadcast star” optical network. DTF exploits tunable components without making excessive demands on tuner agility by combining the tuning on demand of receivers with the forwarding of packets over a logical topology. The authors describe the control algorithms of DTF and prove some results establishing their stability and robustness. They show by simulation that DTF achieves lower hop-counts in conditions of light-to-moderate load than do DeBruijn graph networks. When a DTF network is saturated, the average number of hops in each path is only about 10% higher than the average for a DeBruijn graph network, suggesting that, even under high loads, the evolution of network topology under DTF is close to optimal View full abstract»

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  • Rejection of frequency sweeping signal in DS spread spectrum systems using complex adaptive filters

    Publication Year: 1995 , Page(s): 136 - 145
    Cited by:  Papers (11)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (720 KB)  

    It is already known that the performance of narrowband interference adaptive filtering in DS spread spectrum systems is additionally degraded in the presence of a frequency hopped jamming signal compared to the case with CW interference. Even so, the adaptive filter can be rather efficient because during the hopping interval, while the jamming signal parameters are constant, the filter adjusts its weights; and if the hopping rate is not too high, there are time periods when the interfering signal is suppressed. In order to have a better insight into the performance of these systems, we analyze the DS spread spectrum receiver behavior, when the jamming signal frequency is continuously changing (chirp signal). We find that this is a reasonable step for a jammer that is trying to be more efficient. In such a case, a two-sided filter structure shows worse overall performance than a prediction error structure. As the jamming frequency sweeping rate or bandwidth is increased, the system performance is degraded. The analysis provides an insight into how much the system performance will be degraded as a function of the interfering (frequency sweeping) signal parameters View full abstract»

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  • Multilevel block codes for Rayleigh-fading channels

    Publication Year: 1995 , Page(s): 24 - 31
    Cited by:  Papers (13)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (660 KB)  

    New multilevel block codes for Rayleigh-fading channels are presented. At high signal-to-noise ratios (SNRs), the proposed block codes can achieve better bit error performance over TCM codes, optimum for fading channels, with comparable decoder complexity and bandwidth efficiency. The code construction is based on variant length binary component block codes. As component codes for the 8-PSK multilevel block construction, the authors propose two modified forms of Reed-Muller codes giving a good trade-off between the decoder complexity and the effective code rates. Code design criteria are derived from the error performance analysis. Multistage decoding shows very slight degradation of bit error performance relative to the maximum likelihood algorithm View full abstract»

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  • Authors' reply to comments on “Asymptotically optimum space-diversity detection in non-Gaussian noise”

    Publication Year: 1995
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (92 KB)  

    Maras and Goutis (IEE Proc. I, Commun., Speech Vision, vol. 136, Aug.1989, p.233-40) commented on the paper by Izzo and Paura (IEEE Trans. Commun., vol. COM-34, p.97-103, Feb. 1986). The present paper summarizes the comments of Maras and Goutis and replies to each View full abstract»

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  • Fundamental structures and asymptotic performance criteria in decentralized binary hypothesis testing

    Publication Year: 1995 , Page(s): 32 - 43
    Cited by:  Papers (11)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (924 KB)  

    Two fundamental distributed decision network structures are considered: the first system consists of finite number of sensors, each collecting asymptotically many data, while the second one employs asymptotically many sensors, each collecting a single datum. For binary hypothesis testing, the Neyman-Pearson criterion is utilized and justified via information theoretic arguments. An asymptotic relative efficiency performance measure is used to establish tradeoffs between the two structures, by comparing the performance characteristics of the decentralized detection systems to their centralized counterparts View full abstract»

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  • An effective go-back-N ARQ scheme for variable-error-rate channels

    Publication Year: 1995 , Page(s): 20 - 23
    Cited by:  Papers (25)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (332 KB)  

    In nonstationary channels, error rates vary considerably. The author proposes an effective go-back-N ARQ scheme which estimates the channel state in a simple manner, and adaptively switches its operation mode in a channel where error rates vary slowly. It provides higher throughput than other comparable ARQ schemes under a wide variety of error rate conditions View full abstract»

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  • Unconventional cryptographic keying variable management

    Publication Year: 1995 , Page(s): 3 - 6
    Cited by:  Papers (61)  |  Patents (16)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (392 KB)  

    We present three unconventional approaches to keying variable management. The first approach is based on using a public key cryptosystem (PKC) that is breakable in short, but on average less, time than it takes to set up an ultrawide bandwidth modem that is then used to transport a keying variable for a classical cryptosystem. The second concept proposes using the characteristics of an urban UHF radio channel, determined by mutual sounding, as the cryptovariable. The third concept encourages research into ill-conditioned problems as potentially fruitful ground for PKCs not based on finite field arithmetic View full abstract»

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  • A subcarrier multiplexed CDM optical local area network, theory and experiment

    Publication Year: 1995 , Page(s): 75 - 87
    Cited by:  Papers (11)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1032 KB)  

    A hybrid scheme is proposed for the purpose of suppressing the effects of external modulation and/or laser nonlinearities in subcarrier multiplexing (SCM) fiber optic communications systems. Hybrid CDMA/FDMA combines two schemes in such a way that the resulting hybrid network is robust against interference and is much more spectrally efficient than a CDMA system. Several possible architectures are introduced for the hybrid CDMA/FDMA subcarrier fiber optic local area network (LAN). The networks utilize CDMA and SCM, an asynchronous multiple access scheme. Direct sequence spread spectrum multiple access (DS/SSMA), the most common form of CDMA is employed. It is shown that by using the code sequence sets for which the shift-and-add property holds, intermodulation products (IMPs) and harmonics have a similar interference-like effect as nonmatching sequences do. Owing to the fact that the shift-and-add property holds for conventional spreading sequences, suppression of nonlinear distortions is examined. An average error probability performance evaluation of the selected configuration is presented for a transceiver pair. In analysis of the system, the authors assume the interference term arising from other users is Gaussian distributed. The results are compared to that obtained by exact evaluation of interference distribution using Gauss quadrature rule integration method. The authors compare the performance of this scheme for two different code sequence lengths. They also present some preliminary experimental results on the proposed LAN implementation as well as its measured transmission performance View full abstract»

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  • Bit-error rates for optical receivers using avalanche photodiodes with dead space

    Publication Year: 1995 , Page(s): 99 - 106
    Cited by:  Papers (11)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (724 KB)  

    Bit-error rates are computed for an on-off keying optical communication system using avalanche photodiodes (APDs). We use a model for the APD that includes dead space and the finite response time. Dead space is the minimum distance that a newly generated carrier must travel in order to acquire sufficient energy to become capable of causing an impact ionization in the multiplication region of the APD. The detector's finite impulse response and its randomness are important for high data-rate systems. Using an exact analysis, we show that the presence of dead space enhances the performance at relatively low data rates. Using a Gaussian approximation technique with the exact mean and variance, we demonstrate that dead space degrades the performance at-high data rates since it is responsible for longer tails in the impulse response function of the APD, which in turn increases the effect of intersymbol interference View full abstract»

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IEEE Transactions on Communications focuses on all telecommunications including telephone, telegraphy, facsimile, and point-to-point television by electromagnetic propagation.

 

 

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Editor-in-Chief
Robert Schober
University of British Columbia