Scheduled System Maintenance:
On May 6th, single article purchases and IEEE account management will be unavailable from 8:00 AM - 12:00 PM ET (12:00 - 16:00 UTC). We apologize for the inconvenience.
By Topic

Communications, IEE Proceedings-

Issue 5 • Date Oct 1996

Filter Results

Displaying Results 1 - 14 of 14
  • Array codes over rings and their trellis decoding

    Publication Year: 1996 , Page(s): 241 - 246
    Cited by:  Papers (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (500 KB)  

    A class of array codes over rings of integers modulo-q with good Euclidean distance properties is introduced. Depending on the design, these codes can have linear or nonlinear properties. An extension of a simple algorithm to design a low-complexity trellis diagram for array codes over GF(2) introduced previously is developed for array codes over rings. These codes over rings are compared to the corresponding codes over GF(2), where particular attention is given to the coding gain, spectral efficiency, codebook size and trellis complexity. It is shown that array codes over Z4 and Z8 provide a two-fold and three-fold increase, respectively, in spectral efficiency as well as a higher coding gain over uncoded transmission and a much larger codebook than that obtained with the same array codes over GF(2) for similar code parameters View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Lossless packet switching with small buffers

    Publication Year: 1996 , Page(s): 335 - 340
    Cited by:  Papers (2)  |  Patents (2)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (664 KB)  

    Packet switching and the switching of asynchronous transfer mode (ATM) cells depend on buffering. The amount of buffering required by a packet switch is affected by the burstiness of the data stream. Even if the data stream is uniform at its source, the stream may become bursty as it passes through switches and is subject to contention with other data streams. For a network of output buffered switches, if the incoming data streams are periodic, then the streams emerging from the switches after contention are also periodic. By imposing a period on the network, a packet switch can be designed that is lossless even when each input channel operates at its maximum rate, provided that no output channel is overloaded. Such a switch requires relatively small buffers, smaller than the buffers required by a comparable switch with Poisson arrivals. It is also shown that the use of reserved time slots limits the buffering requirements over a sequence of connection establishments and terminations. The advantage of our strategy is that it minimises the size of the expensive high speed optical buffers in the backbone network View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Simple method for generating distance spectrum and multiplicities of convolutional codes

    Publication Year: 1996 , Page(s): 247 - 249
    Cited by:  Papers (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (268 KB)  

    The author presents a simple algorithm for generating the distance spectrum and multiplicities of convolutional codes. It is different from the existing methods in that no topological searching or matrix inversion is involved. Instead, the method presented consists of the recursion of a set of difference equations with a properly selected operational sequence. The computational cost of the new algorithm can be easily predicted and is modest View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Increasing the capacity of GSM cellular radio using adaptive antennas

    Publication Year: 1996 , Page(s): 304 - 310
    Cited by:  Papers (18)  |  Patents (8)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (652 KB)  

    The capacity of mobile cellular radio networks can be considerably increased if a higher level of cochannel interference can be tolerated. An adaptive antenna combines the outputs of an array of elements to maximise the wanted signal and suppress interfering signals. The author proposes an adaptive antenna algorithm suitable for GSM and the urban multipath environment. The algorithm is based on iterative reference signal reconstruction from the GSM training sequence. The average error rate is obtained by simulation for four equal power interfering signals and an urban GSM multipath model. An adaptive antenna can only practically be deployed at the base station. Realising its gains in a real network on both the up and downlinks requires, for the downlink, a number of techniques. This is discussed and a concept of how the full capacity gains can be achieved in an evolutionary manner on both links is proposed. The concept is equally applicable to the DCS 1800 and DCS 1900 systems based on GSM View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Use of second order Markov chains to model digital symbol synchroniser performance

    Publication Year: 1996 , Page(s): 250 - 258
    Cited by:  Papers (3)  |  Patents (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (876 KB)  

    A second order Markov chain model is used to evaluate the performance of a binary quantised data transition tracking loop (DTTL). At small and moderate signal-to-noise ratios (SNRs), where a first order model is inaccurate for some common pulse shapes, the second order model closely approximates simulated results. The effects of two common loop filters (LFs) on the DTTL performance is also investigated. A first order model accurately predicts performance for moderate and large K for an accumulating LF, which sums K successive timing error estimates. However, an example shows that for a random walk LF with K states, the first and second order models can predict increasingly different performance as K becomes larger View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Adaptive phase diversity for MDPSK reception

    Publication Year: 1996 , Page(s): 267 - 272
    Cited by:  Papers (1)  |  Patents (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (540 KB)  

    Adaptive phase diversity reception that uses only differentially detected phase information is proposed for the differential phase detection (DPD) of Rayleigh faded M-ary differentially encoded phase shift keying (MDPSK) signals. An M-state Viterbi algorithm (VA) is used both for MDPSK phase detection and adaptive estimation of the phase error variance of each diversity branch. The phase error variance is estimated along the surviving path in the trellis, where each state in the trellis represents one MDPSK phase, and its inverse is used as the diversity combining weight. Simple yet efficient MDPSK phase detection based on a decision feedback algorithm (DFA) is also presented. Since there is no need to measure the received instantaneous power for diversity combining, the proposed diversity reception scheme is considered to be very practical. The average bit error rate (BER) performance in the presence of additive white Gaussian noise (AWGN), Doppler spread, multipath delay spread and cochannel interference (CCI) is evaluated by computer simulations for 4DPSK signal transmission in Rayleigh fading channels View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Analysis of mobile radio channel sounding measurements in inner city Dublin at 1.808 GHz

    Publication Year: 1996 , Page(s): 311 - 316
    Cited by:  Papers (14)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (664 KB)  

    It is shown that once the linearity of a channel sounder is established, its ability to resolve paths in the delay-Doppler domain is best described by the ambiguity function. The ambiguity function for the sounder employed in these measurements, together with preliminary channel sounding measurements in inner city Dublin at 1.808 GHz, are reported for the first time. Channel sounding measurement analysis techniques are then described in detail and are applied to the measured data. The K-S goodness-of-fit test is presented as a systematic method of analysing the statistics of the measured data and is shown to give an accurate and objective measure of the goodness-of-fit View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Call blocking performance for dynamic channel allocation technique in future mobile satellite systems

    Publication Year: 1996 , Page(s): 289 - 296
    Cited by:  Papers (6)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (784 KB)  

    Different dynamic channel allocation (DCA) approaches based on the evaluation of a cost function are proposed. The scenario considered is low Earth orbit and geostationary orbit mobile satellite systems. A suitable user mobility model has been defined to generate interbeam handover requests. Different alternatives to manage interbeam handovers have been investigated. Among them, the most promising solution seems to be the queuing of handover requests. The quality of service parameters that have been considered are: the blocking probability for new call arrivals, handover failure probability and the probability of incompletely served call owing to the initial blocking or to the failure of a subsequent handover request. Comparisons among the proposed DCA techniques and the fixed channel allocation technique have been carried out to find a solution that represents a good trade-off between the blocking performance and the required signalling load View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Procedure for automatic recognition of analogue and digital modulations

    Publication Year: 1996 , Page(s): 259 - 266
    Cited by:  Papers (22)  |  Patents (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (692 KB)  

    A global procedure for recognition of analogue and digital modulation types, utilising the decision-theoretic approach, is developed. It involves two main steps: a reliable classification of the signal according to its amplitude and phase information contents; and a classification of the signal according to the modulation type. Computer simulations for different types of band-limited modulated signals corrupted with band-limited Gaussian noise sequences have been carried out. It is found that the threshold SNR for correct signal classification is about 10 dB View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Statistical multiplexing of random processes in packet switching networks

    Publication Year: 1996 , Page(s): 325 - 334
    Cited by:  Papers (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (852 KB)  

    The authors present an analytical model for the closed form evaluation of relevant parameters characterising the process at the output of a statistical multiplexer. Compared with previous approaches, the proposed method is able to additionally describe transient conditions and, through the autocorrelation function and the mean length of adjacent packets sequences, to evaluate the extent of the correlation in the output process as a function of that in the input traffic, also taking into account the effect due to a finite buffer size. The reliability of the model is tested, under different operation conditions, by comparison with simulated results, showing everywhere an excellent agreement View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Ring-TCM for fixed and fading channels: land-mobile satellite fading channels with QAM

    Publication Year: 1996 , Page(s): 281 - 288
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (772 KB)  

    The authors investigate ring-TCM codes suitable for M-QAM signal sets on nonfrequency-selective fading channels. A new range of nonrotational invariant (NRI) and rotational invariant (RI) fading-optimised ring-TCM codes suitable for rectangular M-QAM schemes is presented. The trade off between the code gain and the decoder complexity of these codes is analysed, and their actual performance under different fading channel conditions is evaluated. In addition, a comparison with the best fading-optimised TCM codes for M-QAM reported in the literature is carried out View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Ring-TCM for M-PSK modulation: AWGN channels and DSP implementation

    Publication Year: 1996 , Page(s): 273 - 280
    Cited by:  Papers (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (684 KB)  

    The authors present a code design strategy and implementation of a coded modulation technique based on rings of integers modulo-M. New ranges of AWGN-optimised nonrotational invariant (NRI) and transparent ring-TCM codes suitable for M-PSK modulation are shown View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Performance of fault tolerant ATM switches

    Publication Year: 1996 , Page(s): 317 - 324
    Cited by:  Papers (4)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (676 KB)  

    The authors propose a new, high performance self routing fault tolerant asynchronous transfer mode (ATM) switching network for B-ISDN which employs an enhanced scheme of the banyan network. It consists of two banyan networks with links provided at every stage to allow cell transfer to and from each banyan plane, thereby offering multiple paths between each input-output pair and giving it a high degree of fault tolerance and overcoming the single path limitation of banyan networks. Using simulations, the proposed network is shown to offer better performance than other networks in terms of cell loss rates with or without the presence of faults in the network. Its architecture offers high throughput, low and fixed amount of delay, maintenance of cell sequence, cost effectivity, simple routing, modularity and priority of messages. Furthermore, the authors examine the reliability, mean time to failure and availability of the proposed network vis-a-vis other switching networks. Numerical results show the proposed network to be better than other switching networks View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Estimated bit error probability of DS-SSMA/MDPSK with differential phase detector on satellite mobile channel

    Publication Year: 1996 , Page(s): 297 - 303
    Cited by:  Papers (2)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (480 KB)  

    The performance of direct-sequence spread-spectrum multiple-access (DS-SSMA) systems with M-ary differential phase shift keying (MDPSK) and a differential phase detector (DPD) are estimated on the satellite mobile channel (SMC) which includes Gaussian and Rayleigh channels as the special cases. Numerical results are presented for the system with one of three types of chip waveforms (rectangular, cosine and root Nyquist filtering (RNF)), and binary or complex random signature sequences. They show that the system with the complex random signature sequences outperforms the system with the binary random signature sequences on Gaussian and Rician (K=10) channels, while on a Rayleigh channel both systems perform similarly; the system with 2×I users and BDPSK signalling format outperforms that with I users and QDPSK for Gaussian and Rician (K=10) channels; and from the point view of both bandwidth efficiency and antimultipath effects, the cosine pulse shaping is the best choice of the three pulse shape functions, although the system with the RNF has the highest bandwidth efficiency View full abstract»

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