IEEE Communications Letters

Issue 12 • Dec. 2000

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Displaying Results 1 - 17 of 17
  • Comments on "Capacity evaluation for DS-CDMA systems with multi-class on/off traffic"

    Publication Year: 2000, Page(s):381 - 383
    Cited by:  Papers (3)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (64 KB)

    For original article by S.J. Lee and D.K. Sung see ibid., vol.2, no.6, p.153-5, (June 1998). We propose an efficient iterative algorithm for computing the optimum received power levels corresponding to traffic classes in the reverse link of direct sequence-code division multiple access (DS-CDMA) systems with multi-class traffic. The proposed algorithm converges much faster to the optimum values as... View full abstract»

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  • Space-time block codes: a capacity perspective

    Publication Year: 2000, Page(s):384 - 386
    Cited by:  Papers (258)  |  Patents (6)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (79 KB)

    Space-time block codes are a remarkable modulation scheme discovered recently for the multiple antenna wireless channel. They have an elegant mathematical solution for providing full diversity over the coherent, flat-fading channel. In addition, they require extremely simple encoding and decoding. Although these codes provide full diversity at low computational costs, we show that they incur a los... View full abstract»

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  • Performance of antenna array systems with optimum combining in a Rayleigh fading environment

    Publication Year: 2000, Page(s):387 - 389
    Cited by:  Papers (19)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (85 KB)

    The effect of cochannel interference on the performance of digital mobile radio systems in a Rayleigh fading environment is studied. The average bit error rate (BER) of an antenna array system with an optimum combining scheme that maximizes the output signal-to-interference-plus-noise ratio (SINR) is analyzed. BER expressions which are easy to evaluate numerically are derived for coherent binary p... View full abstract»

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  • On the downlink throughput of a broadband LEO satellite network with hopping beams

    Publication Year: 2000, Page(s):390 - 393
    Cited by:  Papers (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (118 KB)

    In this letter, we analyze the throughput of the downlink segment of a low Earth orbit (LEO) global broadband satellite network. The downlink design uses a set of hopping spot beams, each of which can he pointed independently to any fixed earth cell within the satellite footprint on a per-packet basis. We present upper and lower bounds on the downlink throughput as a function of the number of spot... View full abstract»

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  • Modeling mis-routing calls due to user mobility in wireless VoIP

    Publication Year: 2000, Page(s):394 - 397
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (164 KB)

    This letter proposes an analytic model to study the mis-routing problem caused by user mobility in a wireless VoIP system. We derive the probability that there are n mis-routed calls when a subscriber moves from IP network to the GSM network. Our study indicates that if the user residence times in GSM location areas, inter-call origination times and the inter-call delivery times are of the same or... View full abstract»

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  • Interference bounds in power controlled systems

    Publication Year: 2000, Page(s):398 - 401
    Cited by:  Papers (3)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (92 KB)

    Capacity in a code-division multiple access (CDMA) cellular system is often referred to in terms of the maximum number of users that can be supported within a carrier to interference ratio above a specified quality threshold. This paper presents a simple analysis showing that the total mean interference in the reverse channel, in a multi-tier scenario of a CDMA system with power control, is finite... View full abstract»

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  • A Coxian model for channel holding time distribution for teletraffic mobility modeling

    Publication Year: 2000, Page(s):402 - 404
    Cited by:  Papers (19)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (64 KB)

    In this letter, we derive an algebraic set of equations that examines the relationships between the cell residence times and the handoff call's channel holding time. When the cell residence times have an Erlang or Hyper-Erlang distribution, the channel holding times can be represented by a Coxian model. An algorithm is presented to compute the parameters of the equivalent Coxian model. The analyti... View full abstract»

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  • Bi-directional SOVA decoding for turbo-codes

    Publication Year: 2000, Page(s):405 - 407
    Cited by:  Papers (10)  |  Patents (3)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (48 KB)

    In this letter, we present a bi directional SOVA-based decoding scheme for turbo-codes, which combines the soft-outputs provided by both forward and backward SOVA decodings. Importantly, we explain why this bi-directional decoding improves SOVA decoding. The simulation results show that bi-directional SOVA can achieve about the same performance as the Max-Log-MAP algorithm in turbo decoding. View full abstract»

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  • Fuzzy channel-optimized vector quantization

    Publication Year: 2000, Page(s):408 - 410
    Cited by:  Papers (3)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (63 KB)

    A novel fuzzy clustering algorithm for the design of channel-optimized source coding systems is presented in this letter. The algorithm, termed fuzzy channel-optimized vector quantizer (FCOVQ) design algorithm, optimizes the vector quantizer (VQ) design using a fuzzy clustering process in which the index crossover probabilities imposed by a noisy channel are taken into account. The fuzzy clusterin... View full abstract»

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  • Restart marker regulation technique for progressive JPEG image coding in mobile communications

    Publication Year: 2000, Page(s):411 - 413
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (63 KB)

    In this letter, an error-robust and JPEG compliant progressive image compression scheme over wireless channels is presented. The use of restart markers in the JPEG standard provides the resynchronization function for error handling. Unfortunately, misinterpreted markers may cause serious error damage due to the error propagation. Therefore, a restart marker regulation technique is proposed here to... View full abstract»

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  • Carrier frequency offset compensation for uplink of OFDM-FDMA systems

    Publication Year: 2000, Page(s):414 - 416
    Cited by:  Papers (118)  |  Patents (6)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (79 KB)

    A frequency offset compensation method for OFDM-FDMA, that can correct offsets after the DFT via circular convolution, is proposed as an alternative to the direct method that corrects frequency offsets by multiplying the complex exponents of the offset estimates before the DFT. In contrast to the direct method whose complexity increases proportional to the number of users, the computational load o... View full abstract»

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  • Traffic shaping for a loss system

    Publication Year: 2000, Page(s):417 - 419
    Cited by:  Papers (3)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (71 KB)

    We consider a loss system in which the connection arrival process is deterministically regulated (by leaky buckets for example) but is otherwise arbitrary. Bounds are found on connection blocking probabilities. These bounds are only in terms of the parameters of the traffic regulator, the common connection holding time distribution (which is not regulated in any way) and the server system itself. View full abstract»

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  • Effect of nodes reordering on the schedulability of real-time messages in timed token networks

    Publication Year: 2000, Page(s):420 - 422
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (70 KB)

    This letter addresses the effect of different ordering patterns of network nodes on the ability to schedule real-time messages in a timed token network where the timed token medium access control protocol is employed. It is found that for any given setting of network parameters, a set of real-time message streams which is unschedulable under one particular nodes-ordering may become schedulable und... View full abstract»

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  • Analysis of a new broadcast protocol for satellite communications

    Publication Year: 2000, Page(s):423 - 425
    Cited by:  Papers (2)  |  Patents (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (71 KB)

    In this letter, we propose a tandem broadcast selective repeat (SR) ARQ scheme for satellite communications. In the scheme, the satellite operates in a store and forward manner, which minimizes the effect of the large round-trip delay. Numerical results show that the proposed scheme would largely improve the system performance. View full abstract»

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  • List of reviewers

    Publication Year: 2000, Page(s):426 - 427
    Request permission for commercial reuse | PDF file iconPDF (9 KB)
    Freely Available from IEEE
  • Author Index

    Publication Year: 2000, Page(s):6 - 10
    Request permission for commercial reuse | PDF file iconPDF (52 KB)
    Freely Available from IEEE
  • Subject Index

    Publication Year: 2000, Page(s):010 - 022
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    Freely Available from IEEE

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IEEE Communications Letters publishes letters on the frontiers of research within the field of interest of the IEEE Communications Society in a timely manner.

 

 

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Meet Our Editors

Editor-in-Chief
Octavia Dobre
Memorial University, Canada