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Communications, IEEE Transactions on

Issue 1 • Date Jan 1989

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Displaying Results 1 - 13 of 13
  • Performance of binary FSK communications over frequency-selective Rayleigh fading channels

    Page(s): 83 - 89
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (504 KB)  

    The performance of binary frequency-shift-keyed communications over frequency-selective wide-sense-stationary uncorrelated-scattering Rayleigh fading channels is discussed. Previous analyses of FSK communications over frequency-selective channels have considered the average probability of error for specific models for the fading channel and typically assume that the two FSK signals are orthogonal. A technique for obtaining bounds on the average error probability for FSK in terms of one or two parameters obtainable from multipath spread or frequency correlation functions channel measurements is described View full abstract»

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  • Modeling an asynchronous data echo canceller

    Page(s): 75 - 79
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    It is shown that an adaptive echo canceller with asynchronous inputs affected by sampling time jitter can be modeled as the identification of a time-varying channel by an adaptive filter, both the channel and the adaptive filter being fed with synchronous data. This allows application of theoretical results of the identification problem which are already known. It is proved that the problem is similar when the transmitter itself is slaved on an external jittered clock and the echo canceller is synchronous View full abstract»

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  • Performance analysis of an asymptotically quantum-limited optical DPSK receiver

    Page(s): 46 - 51
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (528 KB)  

    An optical, direct-detection differential phase-shift keying (DPSK) receiver whose error probability is quantum-limited as the transmitting laser linewidth vanishes is analyzed. The receiver design is based on a binary equiprobable hypothesis test with doubly stochastic point process observations, the conditional random rates of which depend on the transmitting laser phase noise, which is modeled as a Brownian motion. The receiver structure consists of a simple delay-and-sum optical preprocessor followed by a photoelectric converter and an integrate-and-dump circuit. Upper and lower bounds on the receiver bit error rate are derived by developing bounds on the conditional rates of the point process, and it is shown that the error probability bounds converge to the true value as the transmitting laser linewidth decreases. Bounds on the power penalty are computed for parameters corresponding to existing semiconductor injection lasers, and are seen to be less than the limiting power penalty for the balanced DPSK receiver View full abstract»

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  • Performance of a broadcast packet switch

    Page(s): 60 - 69
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    The results of a simulation study undertaken to evaluate a high-performance packet-switching fabric supporting point-to-point and multipoint communications are presented. This switching fabric contains several components, each based on conventional binary routing networks. The most novel element is the copy network, which performs the packet replication needed for multipoint connections. Results characterizing the performance of the copy network are presented. Several architectural alternatives for conventional binary routing networks are also evaluated. For example, the performance gains obtainable by using cut-through switching in the context of binary routing networks with small buffers are quantified. One surprising result is that networks constructed from nodes with more then two input and output ports can perform less well than those constructed from binary nodes. This result is quantified and explained View full abstract»

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  • On the symbol error probability of maximum-selection diversity reception schemes over a Rayleigh fading channel

    Page(s): 79 - 83
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    The symbol error probability of two selection schemes, namely, maximum signal-to-noise ratio (Mγ) selection and maximum output (MO) selection, for M-ary multidiversity reception over a Rayleigh fading channel are discussed. The symbol error probability of the MO scheme is lower than that of the Mγ scheme. The more diversity receptions that are used, the larger is the difference. A simple expression of crossover average signal-to-noise ratio (per bit) is presented as a guideline for increasing the number of diversity receptions View full abstract»

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  • A comparison of SSB-SC and conventional AM under a peak power limitation

    Page(s): 1 - 5
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    Single-sideband (SSB) and AM signals are analyzed using a waveform that can be varied in shape from a spike through a sine wave to a square wave by varying a parameter. The average sideband powers and the peak envelope powers are then calculated and compared. It is shown that the ratio of average sideband power to peak envelope power for AM is more favorable than that for SSB for `squarish' modulating signals. However, the ratio for SSB is about 9 dB higher than it is for AM for modulating signals ranging in shape from a sine wave to a spike View full abstract»

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  • Local access radio interference due to building reflections

    Page(s): 70 - 74
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    A computer simulation for studying the interference effects of building reflections on the system performance of local access radio (LAR) is described. The simulation is based upon geometric optics. Coverage probability, defined as the fraction of subscriber locations that can be served by radio within a given range, is calculated. It is shown that only half of the potential subscriber sites within the range of the node can be served by the node site. Of those, a majority are not limited by self-interference caused by reflections. Most of the strong interferences come from structures near the subscriber. Increasing the node mast height has little effect on the coverage. Changing node antennas from three 120° sectors to six sectors, each covering 60°, does not effect the coverage probability. Coverage can be increased by increasing the subscriber mast height. Up to half of the subscribers not served by a node site may be served by an optimally placed node site using different channel frequencies View full abstract»

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  • One-stage one-sided rearrangeable switching networks

    Page(s): 52 - 56
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    Switching networks consisting of subscriber lines and crosswires connected by switches are considered. A connection between two subscribers is made along one crosswire via two switches. The minimum number of switches necessary for such a switching network to be rearrangeably nonblocking is determined and a switching arrangement which achieves this minimum for any (even) number of subscriber lines is constructed. Two procedures for assignment of crosswires to subscriber line pairs are described. One makes the correct choice of connection route without backtracking provided all connections are known beforehand; the other determines a rearrangement of existing assignments when a new connection is required. The switching networks which have the minimum number of switches for networks with up to eight subscriber lines and give nonisomorphic solutions for larger networks are characterized View full abstract»

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  • About loss probabilities for general routing policies in circuit-switched networks

    Page(s): 57 - 59
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    A relationship between the intensities of offered traffic and loss probabilities in a circuit-switched network with general routing policies is derived from Markovian analysis. This relation was first derived in the sample overflow case, i.e., primary trunk-groups overflowing on to a secondary trunk group View full abstract»

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  • TDM policies in multistation packet radio networks

    Page(s): 31 - 38
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    A multistation packet radio network with m stations and a finite number of nodes n that uses a conflict-free protocol to access the backbone network of stations through a shared channel is discussed. The goal is to derive an allocation of the channel time slots (time-division multiplexing cycle), so that all transmissions will be conflict-free and some measure of performance (e.g., the expected total weighted throughput, the expected weighted holding cost) will be optimized. The methodology that is used is to bound the performance and to allocate the slots according to the golden ratio policy View full abstract»

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  • Theoretical studies on the performance of lossy photon channels

    Page(s): 39 - 45
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    The effect of channel losses on the capacity of noiseless optical communication systems utilizing the number state is studied. Based on these findings, the photon efficiency of these systems is evaluated in the presence of losses. Then, by comparing the photon efficiency of the number-state pulse-position modulation (PPM) and the coherent-state PPM under certain realistic conditions, it is found that the former is always superior to the latter from the perspective of photon efficiency regardless of losses View full abstract»

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  • A comparison of protocols for a meteor-burst channel based on time-varying channel model

    Page(s): 18 - 30
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    The performance of a meteor-burst (MB) communication system using three different protocols is examined. The protocols were chosen to study the relative advantages of using a simple stop-and-wait automatic repeat request (ARQ) scheme as well as the ability to sense the presence of a channel. It was found that for long messages, the use of the ARQ scheme gave significant performance improvement; however, when the message length was on the order of the average burst length, the use of the ARQ scheme was not helpful. For packet sizes on the order of the average burst length, it was found that the ability to sense the presence of the channel gave about a 20% reduction in the time necessary to complete a message, but for much shorter packet sizes, the channel probing was not needed. The model used to analyze these systems takes into account the time-varying signal-to-noise ratio (SNR) present in a MB channel. The performance predicted by this model is compared to a less sophisticated constant SNR (signal-to-noise) model and its is found that the author's model predicted significantly more optimistic performance View full abstract»

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  • Performance of a meteor-burst communication system using packet messages with variable data rates

    Page(s): 6 - 17
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    The transmitted data rate is a function of the channel state and is varied in such a way as to keep the probability of bit error approximately constant. The performance measure of the system is the probability of successful message completion in a given time span TD. Optimum operational signal-to-noise ratios are found as well as practical limits on the maximum and minimum transmission data rates. It is shown that the adaptive data rate feature provides a significant improvement in system performance as compared to a system transmitting at a fixed data rate. The performance improvement which can be obtained by the use of forward error correction coding is also analyzed. The codes considered are Reed-Solomon codes with rates of 1/3, 1/2, and 2/3. A much simpler expression for the probability of successful completion of a message is derived and used in the optimization search 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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Editor-in-Chief
Robert Schober
University of British Columbia