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Communications, IEEE Transactions on

Issue 4 • Date April 1992

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Displaying Results 1 - 24 of 24
  • Comments on "GMSK with differential phase detection in the satellite mobile channel

    Publication Year: 1992 , Page(s): 666 - 669
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (274 KB)  

    The error probability results shown by I. Korn (see ibid., vol.38, no.11, p.1980-6, 1990) indicate that the error floor is higher for systems with decision feedback (DF). It was concluded that DF gives a lower error probability only for smaller values of the normalized bandwidth B/sub t/T of the premodulation Gaussian filter, higher values of the ratio of powers in the direct and diffuse signal components K, and a lower range of signal-to-noise ratio. It is shown that this conclusion is not correct by theoretically analyzing the case of the land mobile channel where K=0 (or - infinity dB) and deriving a simple closed-form expression for the error probability for 1 bit differential detection with DF. It is shown that DF reduces the error probability for all values of B/sub t/T and signal-to-noise ratios. The formula derived can be easily evaluated not only for Gaussian minimum shift keying (GMSK) but for all partial-response continuous-phase-modulation (PRCPM) signals.<> View full abstract»

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  • Enhanced protocols for hierarchical encryption key management for secure communication in internet environments

    Publication Year: 1992 , Page(s): 658 - 660
    Cited by:  Papers (8)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (244 KB)  

    Two enhancements to a recently published hierarchical encryption key management protocol for end-to-end secure communication in internet environments are outlined. The first one concerns a more reliable authentication of the principals which can be realized by a modification of the message structures being exchanged, while the second one concerns a modified protocol that permits the implementation of the hierarchical key management approach in the widely employed TCP/IP-based network interconnections View full abstract»

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  • A simple upper bound on the error probability for orthogonal signals in white noise

    Publication Year: 1992
    Cited by:  Papers (10)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (56 KB)  

    A simple upper bound on the error probability for the problem of optimum detection of M equal-energy equiprobable orthogonal signals in additive white Gaussian noise is derived. This new bound is always less than or equal to the union bound and is equally simple View full abstract»

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  • Two-stage maximum likelihood estimation for diversity combining in digital mobile radio

    Publication Year: 1992 , Page(s): 676 - 679
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (256 KB)  

    For space diversity, it is shown that it is related to maximal-ratio combining (MRC). Unlike MRC, it allows the receiver to collect diversity signals without gain adjustments or cophasing. Some worst-case bit error rate (BER) simulation results that show the influence of time delay spread, Doppler, shadow loss, and diversity for a seven-cell cluster using quadrature modulation are presented View full abstract»

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  • Message delay analysis for TDMA schemes using contiguous-slot assignments

    Publication Year: 1992 , Page(s): 730 - 737
    Cited by:  Papers (27)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (524 KB)  

    Under a TDMA (time-division multiple-access) scheme, a station shares a multiple-access communications channel by transmitting its messages during its dedicated time slots. An exact result concerning the queue-sizer and message delay analysis of TDMA systems in which a station is allocated multiple consecutive slots per frame is presented. The generating function of the system queue-size for a general independent arrival message process is obtained. Messages consist of a random number of packets, following a geometric distribution. An exact result for the generating function of the message delay for various common message arrival processes and light bounds for the mean message queue-size and delay are then derived. The results are compared to previously derived approximations. It is also proved that a slot allocation scheme which distributes station slots uniformly over the frame yields a message-delay lower bound. The results also apply to the analysis of time-shared reservation schemes View full abstract»

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  • Optimal monitoring strategies for slowly deteriorating repairable systems

    Publication Year: 1992 , Page(s): 661 - 665
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (324 KB)  

    A simple model for determination of an optimal limit on taking corrective action in a slowly deteriorating repairable system is presented. The performance of such a system is assumed to be characterized by a single parameter which is continuously being monitored. The underlying deterioration process is assumed to be governed by a Brownian motion process with a positive drift. When the measured value of the parameter reaches the action limit, the repair/replacement procedure is initiated. The optimal action limit is derived so that the expected long run average total cost is minimized. Some simple numerical examples illustrate the model and the optimization View full abstract»

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  • Data compression of stereopairs

    Publication Year: 1992 , Page(s): 684 - 696
    Cited by:  Papers (76)  |  Patents (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1224 KB)  

    Two fundamentally different techniques for compressing stereopairs are discussed. The first technique, called disparity-compensated transform-domain predictive coding, attempts to minimize the mean-square error between the original stereopair and the compressed stereopair. The second technique, called mixed-resolution coding, is a psychophysically justified technique that exploits known facts about human stereovision to code stereopairs in a subjectively acceptable manner. A method for assessing the quality of compressed stereopairs is also presented. It involves measuring the ability of an observer to perceive depth in coded stereopairs. It was found that observers generally perceived objects to be further away in compressed stereopairs than they did in originals. It is proved that the rate distortion limit for coding stereopairs cannot in general be achieved by a coder that first codes and decodes the right picture sequence independently of the left picture sequence, and then codes and decodes the left picture sequence given the decoded right picture sequence View full abstract»

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  • Fair integration of routing and flow control in communication networks

    Publication Year: 1992 , Page(s): 821 - 834
    Cited by:  Papers (4)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1016 KB)  

    Relationships among delay, throughput, and fairness, three conflicting performance criteria in modern flow-controlled communication networks, are investigated, and an optimal tradeoff among them is defined. Several fair bandwidth sharing schemes are introduced and compared with each other for a variety of network configurations. The results obtained are then utilized to define an optimal operating point (OOP) which maximizes the generalized network power. Given a fixed routing, it is shown that the OOP can be found via any unconstrained optimization algorithm. If rerouting is allowed, it is also shown that the OOP can be found by solving a variant of the multicommodity convex cost network flow problem. An algorithm for this problem is developed and tested for a number of networks. A delay-directive flow control scheme is suggested to realize the OOP in real operating networks, and additional implementation issues are discussed View full abstract»

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  • Analysis of a new thruway communication system with discrete minimal zones

    Publication Year: 1992 , Page(s): 754 - 764
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (764 KB)  

    A mobile communication system for high-speed thruways is currently under consideration in Japan. The system consists of fixed stations installed at regular intervals (2-5 km) along the thruway which are connected to a host computer. Subscribing customers can communicate with the system as they drive through each station's communication zone of minimal type (40-100 m). The authors develop and analyze a stochastic model for this new communication system. The model closely follows the sequence of operations which actually take place according to a communication protocol for handling collisions, and requires no exponential assumptions for the underlying service times. The tradeoff between the total number of stations installed and the probability of successful completion of a task within z km after the initial submission is investigated. Some numerical results are also given for illustrating the tradeoff, with validation via SIMAN simulation View full abstract»

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  • Theory of polarization shift keying modulation

    Publication Year: 1992 , Page(s): 708 - 721
    Cited by:  Papers (47)  |  Patents (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1048 KB)  

    A rigorous analysis of digital coherent optical modulation schemes using the state of polarization as the modulating parameter is presented. The analysis obtains the exact performance of all the polarization-based modulation schemes proposed in the literature so far, including a differential demodulation scheme, named DPOLSK, which does not require either electrooptic or electronic polarization tracking. Preliminary results involving multilevel transmission schemes based on the state of polarization are introduced. A spectral analysis of POLSK signals is also proposed View full abstract»

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  • Accuracy of traffic modeling in fast packet switching

    Publication Year: 1992 , Page(s): 835 - 846
    Cited by:  Papers (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (904 KB)  

    Arrivals of calls, bursts, and packets to a fast packet switching system are governed by different time scales. This feature is used to break down the system performance analysis into layers. The impact of each layer on packet delay and blocking is investigated in isolation by assuming the global equilibrium in the next higher layer and deterministic flow of entities in all lower layers. The one-layer analytical model is developed and used to determine lower and upper estimates of a mean delay and blocking. Numerical results are compared with delays obtained from the multilayer simulation. Results of the analysis indicate that the channel utilization must be kept below a threshold value to avoid overload periods in the burst and call layers. Flow control techniques which can be used for that purpose are briefly discussed View full abstract»

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  • Frame synchronization for optical overlapping pulse-position modulation systems

    Publication Year: 1992 , Page(s): 783 - 794
    Cited by:  Papers (10)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (772 KB)  

    The maximum-likelihood rules for locating data frames in direct-detection optical communication systems utilizing overlapping pulse-position modulation (OPPM) are derived under two distinct assumptions of symbol and chip synchronization, respectively. Various approximations to the optimal rules are identified, as well as upper and lower bounds on the probability of correct synchronization. Further, the problem of sequence design based on a maximum peak-to-sidelobe distance criterion is studied, and upper bounds on peak-to-sidelobe distance for sequences of OPPM symbols are derived. Some good sequences are obtained through a computer search View full abstract»

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  • Golden ratio scheduling for flow control with low buffer requirements

    Publication Year: 1992 , Page(s): 765 - 772
    Cited by:  Papers (6)  |  Patents (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (768 KB)  

    A method of flow control that requires very few buffers to be allocated at each node to virtual circuits (or sessions) that have to transverse many links is described. Transmissions are scheduled using the golden ratio policy of A. Itai and Z. Rosberg (1984). It is shown that the buffer requirements of a session grow at most logarithmically with the number of slots allotted to it. As an immediate consequence, intra-network delays are bounded View full abstract»

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  • Parallelring: a token ring LAN with concurrent multiple transmissions and message destination removal

    Publication Year: 1992 , Page(s): 738 - 745
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (676 KB)  

    A token ring local area network, the parallelring, is introduced. The ability to concurrently support multiple communication paths on a single loop in an efficient and fair manner differentiates the parallelring from earlier ring architectures. This is accomplished by using a message destination removal scheme and, hence, allowing more than one station to transmit a variable-length frame at a time. Simulation studies show that the parallelring exhibits better performance in terms of throughput-delay characteristics than the other token rings. In addition, a priority scheme is used in the parallelring to provide messages of different time constraints with different media access priorities so that it can support media access fairness and real-time services. In the parallelring, error detection and recovery are completely decentralized View full abstract»

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  • Matched median filtering

    Publication Year: 1992 , Page(s): 722 - 729
    Cited by:  Papers (15)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (632 KB)  

    A class of median type filters, called matched median filters, is defined for the estimation of the information which is carried by the amplitude of a noisy signal. These filters form the natural counterpart of linear matched filters in the class of median type filters and are maximum likelihood estimators if the noise is biexponential. Matched median filters are defined both for baseband and passband systems. Their statistical properties are analyzed and simulation results presented View full abstract»

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  • High-speed parallel CRC circuits in VLSI

    Publication Year: 1992 , Page(s): 653 - 657
    Cited by:  Papers (49)  |  Patents (14)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (456 KB)  

    The use of VLSI technology to speed up cyclic redundancy checking (CRC) circuits used for error detection in telecommunications systems is investigated. By generalizing the analysis of a parallel prototype, performance is estimated over a wide range of external constraints and design choices. It is shown that parallel architectures fall somewhat short of ideal speedups in practice, but they should still enable current CMOS technologies to go well beyond 1 Gb/s data rates View full abstract»

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  • Hierarchical visual pattern image coding

    Publication Year: 1992 , Page(s): 671 - 675
    Cited by:  Papers (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (520 KB)  

    A very fast high-compression, high-fidelity, image coding technique termed visual pattern image coding (VPIC) was recently introduced by the authors (1990). A hierarchical version of VPIC termed hierarchical VPIC (HVPIC) is developed here. In HVPIC, coded images of improved visual fidelity relative to VPIC are generated, with increased compressions (routinely exceeding 20:1). Significantly, the computational efficiency of simple VPIC is retained by HVPIC, which utilizes simple VPIC at each resolution level View full abstract»

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  • Performance analysis of direct-detection optical CDMA communication systems with avalanche photodiodes

    Publication Year: 1992 , Page(s): 810 - 820
    Cited by:  Papers (37)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (904 KB)  

    Direct-detection optical code-division multiple-access (CDMA) communication systems with avalanche photodiode (APD) photodetectors are investigated. A Chernoff upper bound, modified Chernoff upper bound, and Gaussian approximation on the probability of bit error are presented for general APDs and arbitrary {0,1}-valued optical signature sequences. Multiple-user interference, shot-noise, and receiver thermal noise effects on the bit error probability are studied in detail. One-coincidence optical orthogonal codes and prime codes are considered in the numerical analysis. Equal-weight orthogonal signaling formats that do not require dynamic estimation of the receiver threshold are proposed. The results suggest that equal-weight orthogonal signaling schemes are preferable to the on-off orthogonal signaling schemes commonly employed in the literature View full abstract»

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  • Error probability of digital modulation in satellite mobile, land mobile, and Gaussian channels with narrow-band receiver filter

    Publication Year: 1992 , Page(s): 697 - 707
    Cited by:  Papers (14)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (608 KB)  

    It is shown how to derive formulas for the error probability for M-ary differential phase shift keying with differential phase detection (DPD) and M-ary frequency shift keying with DPD, limiter-discriminator detection and limiter-discriminator-integrator detection in the satellite mobile channel (SMC) with narrowband receiver filter if such formulas are available for the Gaussian channel. The modification of the formulas involves only a redefinition of the noise power and autocorrelation function. Since the SMC contains as special cases the land mobile (Rayleigh) channel and the Gaussian channel, the derived formulas are valid for these channels as well. In fact the formula for the land mobile channel is in many cases reduced to a closed form, which does not contain an integral. The author computes the error probability for the four systems, and compares their performance assuming a third-order butterworth filter and M=2,4,8 symbols View full abstract»

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  • A model for local/mobile radio communications with correct packet capture

    Publication Year: 1992 , Page(s): 847 - 854
    Cited by:  Papers (9)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (696 KB)  

    The performance of a local/mobile radio communications system utilizing the slotted ALOHA multiple random access protocol is analyzed. The probability of correct packet capture is evaluated for a local/mobile packet radio system using ideal coherent binary phase-shift keying (BPSK) modulation. Both the near/far effect and the effect of Rayleigh fading on the probability of correct packet capture are taken into account, but the effect of thermal noise is neglected since the interference due to competing packets is dominant in practical systems. The probability of correct packet reception is evaluated for a system using spatial diversity. In addition, the effect on system performance of either convolutional coding with hard decision Viterbi decoding or binary linear block coding with hard decision decoding is evaluated. The pseudo-Bayesian algorithm that has been developed to stabilize a packet system based on the slotted ALOHA protocol at maximum channel throughput is found to be adaptable to the local mobile operating environment. For the system considered here, channel throughputs as high as 0.66 can be obtained View full abstract»

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  • A selective-repeat-ARQ protocol for parallel channels and its resequencing analysis

    Publication Year: 1992 , Page(s): 773 - 782
    Cited by:  Papers (9)  |  Patents (51)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (704 KB)  

    A communications system in which multiple parallel channels are available to carry traffic from a transmitter to a receiver is considered, and an extension of the selective-repeat automatic repeat request (SR-ARQ) protocol that dynamically assigns packets to channels for each (re)transmission is presented. Because of selective retransmission, packets arrive at the receiver out of order and must be stored in a resequencing buffer. A queuing model for the resequencing buffer is constructed. The generating function of the buffer occupancy and the packet-delay distribution are derived, and procedures for simplifying the computation are presented. The dynamic assignment scheme is compared with, and shown to have performance superior to, a static assignment scheme View full abstract»

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  • OFDM for data communication over mobile radio FM channels. II. Performance improvement

    Publication Year: 1992 , Page(s): 680 - 683
    Cited by:  Papers (2)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (268 KB)  

    For pt.I see ibid., vol.39, no.5, p.783-93 (1991). The performance of an orthogonal frequency-division multiplexing (OFDM)/frequency modulation (FM) system for data communication over Rayleigh-fading mobile radio channels was analyzed in pt.I. The effects of forward error correction, switching diversity, automatic gain control (AGC), and squelch are studied. It is shown that OFDM/FM works well with switching diversity because OFDM can average out the transients created by switching between antennas. It is also found that the independent error assumption can be used to predict the distribution of the number of errors in a word. The use of squelch produced a small (about 1 dB) performance improvement, whereas the use of AGC provided negligible improvement View full abstract»

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  • Theoretical analysis of phase diversity optical homodyne receiver with FSK demodulation

    Publication Year: 1992 , Page(s): 795 - 809
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (712 KB)  

    A detailed analysis of optical coherent phase diversity single-filtered and dual-filtered frequency-shift keying (FSK) receivers corrupted by shot and phase noise is presented. With delay and cross-product detection, the effect of various parameters, including bandwidths of filters, delay time, frequency deviation and noises, are investigated. The tolerance of phase noise is quite large, when small time delay in the demodulator and appropriately large frequency deviation is selected. It is also shown that there exists an optimal bandwidth for the first filter in the dual-filtered FSK receiver. For a total linewidth equal to half of the bit rate, the power penalty incurred (at BER=10-9) is 1.92 dB when the modulation index is 4, provided that an optimal filter bandwidth and a frequency deviation-delay product of 0.25 are used View full abstract»

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  • Standoff and standoff resolution in deadlock free networks with virtual circuits

    Publication Year: 1992 , Page(s): 746 - 753
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (740 KB)  

    One of the most common approaches to deadlock prevention is a mechanism known as buffer preallocation. The key concept is that buffers are allocated, most usually for a virtual circuit or class of virtual circuits, before any data is transmitted, and this allocation is done in such a way that no deadlocks are possible. This preallocation typically occurs through the transmission of reservation control messages prior to the transmission of normal data traffic. Control traffic deadlock prevention has yet to be studied. It is shown that deadlocks may occur in connection with this initializing control traffic, and that the resolution of such deadlocks must be handled with some care. If such resolution is not handled with sufficient care, a condition termed standoff may result, whereby contention for the allocation of one or more critical buffers results in resource being allocated to none of the contending parties. Protocols that prevent the phenomenon of standoff, thereby ensuring true deadlock-free operation are described 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.

 

 

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Meet Our Editors

Editor-in-Chief
Robert Schober
University of British Columbia