Scheduled System Maintenance:
On Monday, April 27th, IEEE Xplore will undergo scheduled maintenance from 1:00 PM - 3:00 PM ET (17:00 - 19:00 UTC). No interruption in service is anticipated.
By Topic

Communications, IEEE Transactions on

Issue 2 • Date Feb 1992

Filter Results

Displaying Results 1 - 23 of 23
  • Simulation and theoretical results on cluster management and directory management in dynamic hierarchical networks

    Publication Year: 1992 , Page(s): 312 - 324
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1032 KB)  

    A cluster management scheme for dynamic networks, the purpose of which is to maintain the cluster structure of the hierarchical network as a balanced-tree topology is presented. The theoretical time complexity bounds of the cluster management scheme for node birth and death are derived. The effects of the cluster management on gate-connected fixed-node networks under heavy intercluster traffic situations are discussed. In order to show that the scheme can handle realistic communication networks, routing tables and OD pair shortest path routing are used. The settle-down time, throughput, and end-to-end link delays of a network that uses cluster management and a network of the same topology that only uses flooding are compared View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A short-coding error parameter for channels with block interference

    Publication Year: 1992 , Page(s): 237 - 239
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (232 KB)  

    A short-coding error parameter (SCEP) that provides a bound on the average probability of decoding error for codes with length shorter than the memory length is presented. It is shown that this bound is tighter than the bound based on the conventional cutoff rate and that the SCEP is independent of the channel's memory length, provided the codeword length is shorter than the memory length View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Testing of three-stage switching networks for coupling faults

    Publication Year: 1992 , Page(s): 413 - 422
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (792 KB)  

    A coupling fault diagnosis procedure is proposed for digital switching networks constructed of uniform time-division switches. The procedure is executed in two phases. Each phase consists of eight test steps; the number of tests for detecting the most likely coupling faults inside a single switch is independent of the network size. The concept of primitive and convolutional test vectors is introduced in order to analyze test stimuli applied to successive switches during the test. The approach can be easily adapted for use in many modern digital exchanges View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Performance analysis of a growable architecture for broad-band packet (ATM) switching

    Publication Year: 1992 , Page(s): 431 - 439
    Cited by:  Papers (14)  |  Patents (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (656 KB)  

    The performance of a growable architecture for broadband asynchronous transfer mode (ATM) switching consisting of a memoryless self-routing interconnect fabric and modest-size packet switch modules is examined. The cell loss probability is the focus because the architecture attains the best possible delay-throughput performance if the packet switch modules use output queuing. There are two sources of cell loss in the switch. First, cells are dropped if too many simultaneous arrivals are destined to a group of output ports. Second, because a simple, distributed path-assignment controller is used for speed and efficiency, cells are dropped when the controller cannot schedule a path through the switch. The authors compute an upper bound on arrivals, possibly including isochronous circuit connections, and show that both sources of cell loss can be made negligibly small View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Asymptotically optimal design of congestion control for high speed data networks

    Publication Year: 1992 , Page(s): 301 - 311
    Cited by:  Papers (28)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (828 KB)  

    The basic mechanism of sliding windows for the congestion control of virtual circuits is examined. A problem concerning the optimal design of windows is formulated and formulas for basic quantities of interest, such as throughput, delay and moments of packet queues, in the optimal operating regime as well as in other regimes, are obtained. All results are asymptotic, in which the main parameter is λ, the delay-bandwidth product. It is shown that K*~λ+O(√λ), where K* is the optimum window size. Also, in the optimal operating regime, the steady-state mean and standard deviation of the queued packets at individual nodes O(√/λ). The design consequences are examined in the contexts of adaptive dynamic windowing, buffer sizing, and shared versus separate buffers in the case of multiple virtual circuits View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • On the implementation and performance of single and double differential detection schemes

    Publication Year: 1992 , Page(s): 278 - 291
    Cited by:  Papers (58)  |  Patents (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (976 KB)  

    A variety of schemes for performing differential detection in environments characterized by frequency offset are discussed. All of the schemes involve encoding the input phase information as a second-order difference and performing an analogous second-order differential detection at the receiver. Because of the back-to-back differential detection operations at the receiver, The performance of most of the schemes is considerably degraded relative to that of first-order differential detection schemes. However, the latter are quite sensitive to frequency offset and, in many instances, cannot be used at all. It is demonstrated that via a simple enhancement of using a 2 T s (instead of T s) delay in the second stage of the encoder and first stage of the decoder, the performance degradation can be significantly reduced. This result is significant in view of the fact that it comes without any penalty in implementation complexity View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Angle diversity and space diversity experiments on the Salton/Brawley hop

    Publication Year: 1992 , Page(s): 440 - 454
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1196 KB)  

    Space diversity and angle diversity experimental data have been collected over a three year period, using 64 quadrature amplitude modulation (QAM) radios, on the terrestrial microwave radio hop between Salton and Brawley in southern California. Both measured data and simulations have shown that the performance of angle diversity systems depends on the direction of transmission as well as the polarization of the signal. While this may also be true for space diversity, the effects of a finite spatial correlation length and a small signal-to-noise ratio significantly reduce the sensitivity of space diversity to the direction of propagation. Additionally, the performance of angle diversity is shown to depend upon the method used to implement angle diversity View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Maximum-likelihood receiver for four-dimensional signaling schemes corrupted by ISI

    Publication Year: 1992 , Page(s): 265 - 277
    Cited by:  Papers (3)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (972 KB)  

    A maximum-likelihood decision-directed receiver structure is derived for a data transmission system which employs quadrature-quadrature phase shift keying (Q2PSK) as the modulation scheme. The receiver is derived by treating the problem of sequence decision, sample timing, and carrier phase as a composite estimation problem. It is shown that the resulting maximum-likelihood estimates (MLEs) are asymptotically unbiased, and the variances of these estimates are derived. In this receiver, symbol detection is carried out by means of a modified Viterbi algorithm (MVA) while a parallel synchronizer is used for carrier phase and delay recovery. As a measure of performance, an error-event probability bound is derived for the MVA. The effect of intersymbol interference, (ISI) present at the two matched filters' outputs, on the error bound is analyzed and illustrated. It is shown that the resulting MVA and the parallel estimator are well suited for systolic array implementation View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Throughput evaluation of unidirectional broad-band CSMA

    Publication Year: 1992 , Page(s): 246 - 250
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (356 KB)  

    An analysis of the throughput achieved by broadband nonpersistent carrier sense multiple access (CSMA) on the bus topology is discussed. The transmission is unidirectional, with the head-end being either active or passive. A homogeneous infinite number of users is assumed to be uniformly distributed on the bus. It is shown that although unidirectional broadband transmission allows for higher transmission rates, and longer distances, the normalized throughput achieved is less than that achieved by bidirectional broadband or baseband transmission View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Improved decoder for transform coding with application to the JPEG baseline system

    Publication Year: 1992 , Page(s): 251 - 254
    Cited by:  Papers (20)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (280 KB)  

    Transform coding, a simple yet efficient image coding technique, has been adopted by the Joint Photographic Experts Group (JPEG) as the basis for an emerging coding standard for compression of still images. However, for any given transform encoder, the conventional inverse transform decoder is suboptimal. Better performance can be obtained by a nonlinear interpolative decoder that performs table lookups to reconstruct the image blocks from the code indexes. Each received code index of an image block addresses a particular codebook to fetch a component vector. The image block can be reconstructed as the sum of the component vectors for that block. An iterative algorithm for designing a set of locally optimal codebooks is developed. Computer simulation results demonstrate that this improved decoding technique can be applied in the JPEG baseline system to decode enhanced quality pictures from the bit stream generated by the standard encoding scheme View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Improving the performance of a slotted ALOHA packet radio network with an adaptive array

    Publication Year: 1992 , Page(s): 292 - 300
    Cited by:  Papers (43)  |  Patents (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (776 KB)  

    The use of an adaptive antenna array as a means of improving the performance of a slotted ALOHA packet radio network is presented. An adaptive array creates a strong capture effect at a packet radio terminal by automatically steering the receiver antenna pattern toward one packet and nulling other contending packets in a slot. A special code preamble and randomized arrival times within each slot allow the adaptive array to lock onto one packet in each slot. The throughput and delay performance of a network with an adaptive array are computed by applying the standard Markov chain analysis of slotted ALOHA. It is shown that throughput levels comparable to carrier sense multiple access (CSMA) are attainable with an adaptive array without the need for stations to be able to hear each other. The performance depends primarily on the number of adaptive array nulls, the array resolution, and the length of the randomization interval within each slot View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Error probabilities of fast frequency-hopped MFSK with noise-normalization combining in a fading channel with partial-band interference

    Publication Year: 1992 , Page(s): 404 - 412
    Cited by:  Papers (20)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (696 KB)  

    An error probability analysis performed for an M-ary orthogonal frequency-shift keying (MFSK) communication system employing fast frequency-hopped (FFH) spread-spectrum waveforms transmitted over a frequency-nonselective, slowly Rician fading channel with partial band interference is discussed. Diversity is obtained using multiple hops per data bit. Noise-normalization combining is employed by the system receiver to minimize partial-band interference effects. The partial-band interference is modeled as a Gaussian process. Thermal noise is also included in the analysis. Forward error correction coding is applied using convolutional codes and Reed-Solomon codes. Diversity is found to dramatically reduce the degradation of the noise-normalization receiver caused by partial-band interference regardless of the strength of the direct signal component. Diversity offers significant performance improvement when channel fading is strong, and performance improvement is obtained for high modulation orders (M>2). Receiver performance is improved when diversity, higher modulation orders, and coding are combined View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A growable packet (ATM) switch architecture: design principles and application

    Publication Year: 1992 , Page(s): 423 - 430
    Cited by:  Papers (56)  |  Patents (18)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (720 KB)  

    The problem of designing a large high-performance, broadband packet of ATM (asynchronous transfer mode) switch is discussed. Ways to construct arbitrarily large switches out of modest-size packet switches without sacrificing overall delay/throughput performance are presented. A growable switch architecture is presented that is based on three key principles: a generalized knockout principle exploits the statistical behaviour of packet arrivals and thereby reduces the interconnect complexity, output queuing yields the best possible delay/throughput performance, and distributed intelligence in routing packets through the interconnect fabric eliminates internal path conflicts. Features of the architecture include the guarantee of first-in-first-out packet sequence, broadcast and multicast capabilities, and compatibility with variable-length packets, which avoids the need for packet-size standardization. As a broadband ISDN example, a 2048×2048 configuration with building blocks of 42×16 packet switch modules and 128×128 interconnect modules, both of which fall within existing hardware capabilities, is presented View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Block decision feedback equalization

    Publication Year: 1992 , Page(s): 255 - 264
    Cited by:  Papers (41)  |  Patents (13)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (832 KB)  

    A natural generalization of the conventional decision feedback equalizer (DFE) based on block processing and maximum a posteriori decisions is presented. This block DFE is indexed by two parameters depending on the block length p and the number of decisions qp made at each iteration. The block DFE emulates: the conventional DFE when p=q=1; the maximum likelihood sequence estimator when p=q→∞; and the maximum symbol-by-symbol a posteriori optimal detector when q=1, p→∞. For more general (p,q) parameter settings, one achieves combinations and simplifications of these classical nonlinear detectors. The authors also recover more recently developed nonlinear equalizer structures based on forward tree search algorithms in the high SNR limit (for q =1). They simulate the equalizer using a standard literature example. The theoretical framework presented accommodates autoregressive moving average (ARMA) channels models. Investigations into the error performance of the block DFE are briefly discussed View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Achievable information rates on digital subscriber loops: limiting information rates with crosstalk noise

    Publication Year: 1992 , Page(s): 361 - 372
    Cited by:  Papers (32)  |  Patents (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1000 KB)  

    The capacity and cutoff rates for channels with linear intersymbol interference, power dependent crosstalk noise, and additive white noise are examined, focusing on high speed digital subscriber line data transmission. The effects of varying the level of additive white noise, crosstalk coupling gain, sampling rate, and input power levels are studied in detail for a set of simulated two-wire local loops. A closed-form expression for the shell constrained Gaussian cutoff rate on the crosstalk limited channel is developed and related to the capacity, showing that the relationship between these two rates is the same as on a channel without crosstalk noise. The study also projects achievable rates on a digital subscriber line, inside and outside of a carrier serving area, with a sophisticated but realizable receiver View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Distributed multisensor parameter estimation in dependent noise

    Publication Year: 1992 , Page(s): 373 - 384
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (892 KB)  

    The problem of distributed estimation of a weak nonrandom location parameter θ in additive stationary dependent noise is addressed. Multisensor configurations with and without a coordinator are considered. Dependence in the sensor observations is described by m -dependent, φ-mixing, and p-mixing models. Two cases of interest are addressed: one in which sensor observations are dependent across time but independent across sensors and one in which sensor observations are dependent across both time and sensors. Numerical results on the performance evaluation of the various estimation schemes derived are presented and the relative performances of the various schemes are compared View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Tandem transcoding without distortion accumulation for vector quantization

    Publication Year: 1992 , Page(s): 397 - 403
    Cited by:  Papers (2)  |  Patents (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (588 KB)  

    Transcoding algorithms that eliminate distortion accumulation due to tandem transcodings between memoryless, finite-state, and predictive vector quantization and pulse code modulation (PCM) are presented. The algorithms can be implemented using table lookups for memoryless and finite-state vector quantization, whereas predictive vector quantization requires online calculations. Computer simulations indicate a 6 dB improvement in the case of 16 kb/s predictive vector quantizers, 48 kb/s PCM, and four tandems for speech View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Wide-band microwave propagation parameters using circular and linear polarized antennas for indoor wireless channels

    Publication Year: 1992 , Page(s): 240 - 245
    Cited by:  Papers (37)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (532 KB)  

    Results of experiments using a variety of antennas inside several buildings are presented. Path loss models for the 1.3 GHz and 4.0 GHz bands that show little difference in indoor path loss throughout the low-microwave region are discussed. Results show that line-of-sight (LOS) channels offer significantly more cross-polarization discrimination than obstructed channels. A profound result is that directional circularly polarized (CP) antennas always reduce RMS delay spread when compared to omnidirectional and directional linearly polarized (LP) antennas in LOS. The variation of RMS delay spread as a mobile moves over several wavelengths is also greatly reduced when CP antennas are used View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Bounds on the error performance of coding for nonindependent Rician-fading channels

    Publication Year: 1992 , Page(s): 351 - 360
    Cited by:  Papers (38)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (712 KB)  

    New upper bounds on the error performance of coded systems for Rician channels are presented. The fading channels need not be fully interleaved to obtain meaningful performance results. These bounds hold for coherent, differentially coherent and noncoherent demodulation of binary signals. They provide a useful analytical approach to the evaluation of the error performance of convolutional or block coding and they may be generalized to M-ary signals and trellis modulation. The approach allows for complex bounds using the fine structure of the code, for simpler bounds similar to those on memoryless channels and finally for a random coding bound using the cutoff rate of the channel. The analysis thus permits a step by step evaluation of coded error performances for Rician-fading channels View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Predictive ordering technique and feedback transform coding for data compression of still pictures

    Publication Year: 1992 , Page(s): 385 - 396
    Cited by:  Papers (2)  |  Patents (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (992 KB)  

    A picture data compression method consisting of a hybrid cascade having four processing stages is presented. The processing stages are: predictive ordering technique (POT), feedback transform coding (FTC), vertical subtraction of quantized coefficients (VSQC), and predictive coding refinements in the signal space consisting of either overshoot suppression (OS) as a first variant or hybrid block truncation coding (HBTC) as a second one. Each of these stages is described, and reconstructed pictures are presented with their coding fidelity performances (mean square quantization error, mean absolute error and signal-to-noise ratio), using as test pictures a portrait and a LANDSAT image. It is shown that good quality images at low bit rates (0.55 to 1.1 bits/pixel) have been obtained View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • An indirect procedure for counting intermodulation products among narrow-band carriers [satellite links]

    Publication Year: 1992 , Page(s): 345 - 350
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (480 KB)  

    The problem of computing intermodulation generated by a large number of narrowband carriers is examined. In general, narrowband carriers sharing a nonlinear repeater may have different power levels and different spectral shapes. Therefore, different kinds of intermodulation products will appear. It is well known that replacing identical contiguous carriers by a noise band may lead to a poor approximation when baseband computations involving carriers with peaked spectral shapes (e.g. SCPC/FM) are considered. However, it is shown here that this noise band representation offers an effective way to calculate the total RF intermodulation power corresponding to each kind of product and can therefore be viewed as a means of indirectly counting intermodulation products View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Limits to the encoding and bounds on the performance of coherent ultrashort light pulse code-division multiple-access

    Publication Year: 1992 , Page(s): 325 - 336
    Cited by:  Papers (11)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (912 KB)  

    The authors obtain lower and upper bounds on the peak intensity of a spectrally phase encoded ultrashort light pulse as a function of the length of spectral phase encoding. It is shown that using random phase codes for spectral encoding of ultrashort light pulses in a coherent ultrashort light pulse code-division multiple-access (CDMA) system is almost optimal. Furthermore, simple upper bounds and an asymptotic approximation on the bit error rate (BER) for a wide class of ultrashort light pulse CDMA systems are obtained. It is shown that, in spite of being simple, these upper bounds can be used to evaluate the performance of a coherent ultrashort light pulse CDMA system View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Analysis of polling systems with general input process and finite capacity

    Publication Year: 1992 , Page(s): 337 - 344
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (604 KB)  

    An approximate algorithm for polling systems with finite capacity of waiting places and nonexhaustive service is presented. The analysis is made in the discrete-time domain, based on the evaluation of discrete convolution operations taking advantage of fast convolution algorithms, e.g. the fast Fourier transform. Attention is devoted to two essential modeling aspects: consideration of general renewal input traffic, and assumption of finite capacity of waiting places in the system. Numerical examples are shown to illustrate the approximation accuracy of the analysis. The approximation is validated by means of computer simulations. The class of polling models considered here can be used in the performance investigation of a broad spectrum of models in computer and communication systems View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.

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
Robert Schober
University of British Columbia