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IEEE Transactions on Communications

Issue 6 • Date Jun 1994

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Displaying Results 1 - 21 of 21
  • Multiple-access protocols: fairness in heterogeneous systems

    Publication Year: 1994, Page(s):2276 - 2281
    Cited by:  Papers (4)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (576 KB)

    We propose a distributed reservation protocol for high-speed, star-based, local-communication systems with heterogeneous users. The users have different delay, throughput, and priority requirements, and each user has knowledge of only its own traffic mix. At light loads, the usual delay overhead of reservation schemes can be eliminated. Also, the probability of correct reservation reception is imp... View full abstract»

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  • Joint synchronization and demodulation of trellis codes

    Publication Year: 1994, Page(s):2268 - 2275
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (712 KB)

    This paper examines the joint synchronization and detection of Ungerboeck coded modulation. Estimation theory is used to derive a synchronization structure that is efficient in estimating carrier phase and symbol timing. The maximum likelihood receiver generates estimates of carrier phase and timing that are free of data-dependent jitter for any continuous pulse shape. Various feedback schemes to ... View full abstract»

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  • Microdiversity on Rician fading channels

    Publication Year: 1994, Page(s):2258 - 2267
    Cited by:  Papers (48)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (768 KB)

    The performance of an L-branch equal gain (EG) combiner on slow and nonselective Rician fading channels is analyzed. Two performance criteria are considered; the probability distribution of signal-to-noise power ratio (SNR) at the output of the EG combiner and the average bit error rate (BER). Matched filter receivers are considered for two binary modulation formats, coherent phase shift keying (C... View full abstract»

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  • Modeling of signal envelope correlation of line-of-sight fading with applications to frequency correlation analysis

    Publication Year: 1994, Page(s):2201 - 2203
    Cited by:  Papers (20)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (204 KB)

    Based on the theoretical method developed by Clarke (1968) for the analysis of correlation characteristics in Rayleigh fading conditions, we develop a general model for envelope correlation statistics of line-of-sight fading known as Nakagami-Rice fading. The model developed here has a considerable degree of universality and can be applied to the analysis of correlation statistics in frequency and... View full abstract»

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  • Adaptive dimensionality reduction techniques for tree-structured vector quantization

    Publication Year: 1994, Page(s):2246 - 2257
    Cited by:  Papers (4)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1136 KB)

    It is well-known that the exorbitant complexity of vector quantization's codebook design and encoding process have hindered the vector quantization based coding systems for real-time implementations. Tree-structured vector quantization (TSVQ) is one of the most efficient techniques to solve these problems. However, the encoder's memory requirement has increased as compared with the conventional fu... View full abstract»

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  • Performance evaluation of adaptation functions in the ATM environment

    Publication Year: 1994, Page(s):2335 - 2344
    Cited by:  Papers (4)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (888 KB)

    The paper models and evaluates key design issues for the adaptation layer in ATM networks. The role and efficient design of the adaptation layer is crucial for future B-ISDN based on ATM. We concentrate on packet-mode adaptation services analyzing and simulating relevant protocols employed for narrowband ISDN signaling and packet data. Processing and transmission resources are modeled. In particul... View full abstract»

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  • Lattice low-delay vector excitation coding of speech at 8-16 kb/s

    Publication Year: 1994, Page(s):2219 - 2223
    Cited by:  Papers (4)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (420 KB)

    Lattice low-delay vector excitation coding (LLD-VXC) is a speech coding system based on analysis-by-synthesis excitation coding and backward adaptation of the synthesis filter. The introduction of a lattice filter as a (high order) short-term predictor has significant advantages, such as fast tracking of speech signal nonstationarities, simple stability verification, and uniform distribution of th... View full abstract»

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  • Adaptive parameter estimation using parallel Kalman filtering for spread spectrum code and Doppler tracking

    Publication Year: 1994, Page(s):2227 - 2230
    Cited by:  Papers (22)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (324 KB)

    We present a new digital direct-sequence (DS) receiver with joint estimation of code delay, multipath gains and Doppler shift. A parameter estimator consisting of a parallel bank of extended Kalman filters (EKF's) extracts estimates of the timing, τ and the multipath coefficients, fl distorting the received signal. A “detected” estimate of the Doppler shift, v... View full abstract»

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  • Hybrid ARQ schemes employing coded modulation and sequence combining

    Publication Year: 1994, Page(s):2239 - 2245
    Cited by:  Papers (18)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (620 KB)

    In this paper, we propose and analyze two hybrid automatic-repeat-request (ARQ) schemes employing bandwidth efficient coded modulation and coded sequence combining. In the first scheme, a trellis-coded modulation (TCM) is used to control channel noise; while in the second scheme a concatenated coded modulation is employed. The concatenated coded modulation is formed by cascading a Reed-Solomon (RS... View full abstract»

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  • Acquisition of PN sequences in chip synchronous DS/SS systems using a random sequence model and the SPRT

    Publication Year: 1994, Page(s):2325 - 2334
    Cited by:  Papers (25)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (716 KB)

    The use of a sequential probability ratio test (SPRT) for the acquisition of pseudonoise (PN) sequences in chip synchronous direct-sequence spread-spectrum (DS/SS) systems is considered. The out-of-phase sequence is modeled as a random sequence and the probabilities of error and expected sample sizes for the corresponding test are derived. A different (and very commonly used) test is obtained if t... View full abstract»

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  • Adaptive trellis-coded multiple-phase-shift keying for Rayleigh fading channels

    Publication Year: 1994, Page(s):2305 - 2314
    Cited by:  Papers (108)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (864 KB)

    An adaptive scheme for trellis-coded modulation of MPSK signals, called adaptive trellis-coded multiple-phase-shift keying (ATCMPSK), is proposed for slowly Rayleigh fading channels. The adaptive scheme employs a slightly modified rate 1/2 convolutional encoder and the corresponding Viterbi decoder to realize a family of codes of different rates which are employed according to channel conditions. ... View full abstract»

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  • Variable frame rate speech coding using optimal interpolation

    Publication Year: 1994, Page(s):2215 - 2218
    Cited by:  Papers (3)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (336 KB)

    A VFR LPC vocoder using optimal interpolation is presented in this paper. In the encoder, some representative frames of an utterance are selected for transmission. In the decoder, LPC parameters of all untransmitted frames are restored by optimal interpolation. Simulation results show that this coding scheme outperforms the conventional VFR vocoder using linear interpolation. By incorporating cont... View full abstract»

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  • Maximum-likelihood symbol synchronization and detection of OPPM sequences

    Publication Year: 1994, Page(s):2282 - 2290
    Cited by:  Papers (4)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (688 KB)

    For an optical Poisson channel, we consider the problem of symbol synchronization and detection of chip-synchronized, random overlapping pulse-position modulation (OPPM) sequences. Maximum-likelihood algorithms are derived for both synchronization and detection and for soft and hard data, and their performances are evaluated through simulations and an upper bound on the symbol detection and symbol... View full abstract»

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  • Improved decision boundaries of narrowband M-ary CPFSK

    Publication Year: 1994, Page(s):2204 - 2207
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (264 KB)

    Improved decision boundaries of narrowband M-ary CPFSK with limiter discriminator integrator (LDI) detection, differentially coherent (DC) detection and coherent detection with differential decoding (CDDD) receivers are reported at modulation index 1/M. A simple method to determine each improved decision boundary by considering only the two closest symbols to that boundary is discussed. Numerical ... View full abstract»

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  • The performance of two symbol timing recovery algorithms for PSK demodulators

    Publication Year: 1994, Page(s):2345 - 2355
    Cited by:  Papers (30)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (800 KB)

    A statistical analysis of a decision-directed symbol timing algorithm for phase shift keyed modems is presented. The timing detector uses only one sample per symbol period and is suitable for high speed modems which employ discrete-time synchronization methods. Expressions for the timing detector's mean value and variance, as a function of timing offset, are derived and compared to simulation resu... View full abstract»

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  • An alternative derivation for the signal-to-noise ratio of a SSMA system

    Publication Year: 1994, Page(s):2224 - 2226
    Cited by:  Papers (15)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (136 KB)

    We present an alternative derivation for the signal-to-noise ratio (SNR) of a phase-coded spread-spectrum multiple access (SSMA) system by use of ensemble-average approach. We show that our formula can be explicitly expressed in terms of system parameters and the expression for the SNR derived by Pursley (1977) is just a special case when the user number is very large View full abstract»

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  • Convolutional coding for finite-state channels

    Publication Year: 1994, Page(s):2231 - 2238
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (756 KB)

    We propose new decoders for decoding convolutional codes over finite-state channels. These decoders are sequential and utilize the information about the channel state sequence contained in the channel output sequence. The performance of these decoders is evaluated by simulation and compared to the performance of memoryless decoders with and without interleaving. Our results show that the performan... View full abstract»

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  • On the performance of data receivers with a restricted detection delay

    Publication Year: 1994, Page(s):2315 - 2324
    Cited by:  Papers (4)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (872 KB)

    It is well known that the performance of a data receiver for an intersymbol interference (ISI) channel can depend strongly on the detection delay δ. For a discrete-time communication system, this paper derives a lower bound on the bit-error probability as a function of δ. This “restricted delay bound” is governed by a “restricted-delay distance” d(δ). In m... View full abstract»

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  • Theory of polarization spreading techniques-Part II

    Publication Year: 1994, Page(s):2291 - 2304
    Cited by:  Papers (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1072 KB)

    This paper, together with a companion one by Poggiolini and Benedetto (see IEEE Trans. Commun., vol.42, p. 2105-2118, May 1994), constitute a thorough presentation and analysis of a series of techniques grouped under the denomination “polarization spreading”, the intent of which is that of making the performance of a coherent optical receiver insensitive to the polarization transformat... View full abstract»

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  • Coherent subcarrier fiber-optic communication systems with phase-noise cancellation

    Publication Year: 1994, Page(s):2208 - 2212
    Cited by:  Papers (5)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (380 KB)

    A phase-noise-cancelled coherent subcarrier fiber-optic communication system that uses integrated-optic Mach-Zehnder waveguide modulators for frequency-pair encoding is introduced. Optical double-sideband suppressed-carrier signals with the same random phase noise and information encoded in the frequency separation of the two sidebands are generated by properly biasing the modulator. Phase noise i... View full abstract»

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  • Blocking formulae for the Engset model

    Publication Year: 1994, Page(s):2213 - 2214
    Cited by:  Papers (3)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (136 KB)

    Presents simple recursive algorithms for computing call and time congestion in the classical Engset model with M sources and N servers. The first recursion has the complexity of O(MN) and gives the blocking probabilities for all intermediate values of M and N. The second recursion assumes a particular value of M and has the complexity of O(N). It gives the blocking probabilities for all intermedia... View full abstract»

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Aims & Scope

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

 

 

Full Aims & Scope

Meet Our Editors

Editor-in-Chief
Naofal Al-Dhahir
University of Texas at Dallas