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Communications, IEE Proceedings-

Issue 2 • Date Apr 1998

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Displaying Results 1 - 10 of 10
  • Fast decoder for triple-error-correcting primitive binary BCH codes with odd m

    Publication Year: 1998 , Page(s): 60 - 64
    Cited by:  Papers (2)  |  Patents (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (456 KB)  

    A triple-error-correcting primitive binary BCH code with odd m is shown to be the intersection of three Hamming codes each of length n=2 m-1. Using this property, a decoding algorithm for the code is developed. Based on the algorithm, a hardware decoder is designed by the use of five ROMs, each 2m×m bits, and several logic gates. In comparison with conventional decoders, the decoder is simpler in complexity and faster in decoding speed View full abstract»

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  • Capture model for mobile radio slotted ALOHA systems

    Publication Year: 1998 , Page(s): 91 - 97
    Cited by:  Papers (6)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (632 KB)  

    It is well known that the capture effect can considerably improve the system throughput of mobile radio slotted ALOHA networks. Most of the capture models described in the literature are based on the signal-to-interference power ratios, with the assumption that the captured packet is error-free. In the paper, a capture model is proposed for slotted ALOHA systems employing symbol erasures and error-and-erasure correcting codes. In contrast to previous models, the model uses a target bit error rate as the capture measure, which in turn is controlled by a symbol-erasure threshold. Performance of the proposed model is analysed taking into account modulation and coding techniques, the signal-to-noise ratio, the user spatial distribution as well as Rayleigh channel fading View full abstract»

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  • Algorithm for sequential generation of states in failure-prone communication network

    Publication Year: 1998 , Page(s): 73 - 79
    Cited by:  Papers (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (708 KB)  

    An algorithm is presented for sequentially generating the most probable states, in order of decreasing probability, in a failure-prone network, given the failure probability of the components. The developed algorithm is compared with others, regarding its efficiency and memory requirement. Reference is made to a study of the reliability-grade of service of circuit-switched digital urban networks with alternative routing. It is shown that the proposed algorithm is significantly more efficient than other approaches that could be applied to this particular type of problem View full abstract»

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  • Diversity combining with MLSE equalisation

    Publication Year: 1998 , Page(s): 105 - 108
    Cited by:  Papers (5)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (376 KB)  

    Optimum diversity combining and equalisation applied to linear systems is realised using maximum likelihood sequence estimation. It is shown that each received signal should be applied to a filter which is matched to the corresponding diversity channel's impulse response. The output of this set of filters is simply summed, sampled at the symbol rate and input into a maximum likelihood sequence estimator. The performance of this structure is predicted by simulation with MSK and GMSK modulations using a GSM channel model. Even though GMSK is not linear, the nonlinearity is ignored and the receiver structure is made the same in both cases View full abstract»

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  • Adaptive Volterra channel equalisation with lattice orthogonalisation

    Publication Year: 1998 , Page(s): 109 - 115
    Cited by:  Papers (1)  |  Patents (4)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (604 KB)  

    The authors present a new recursive least-squares adaptive nonlinear equaliser based on Volterra series expansion. The main approach is to transform the nonlinear equalisation problem into an equivalent multichannel, but linear, equalisation problem. Then the multichannel input signal is completely orthogonalised using sequential processing multichannel lattice stages. With the complete orthogonalisation of the input signal, only scalar operations are required, instability problems owing to matrix inversion are avoided, and good numerical properties are achieved. Avoidance of matrix inversion and vector operations reduce the complexity considerably, and make the filter highly modular and suitable for VLSI implementation. Several experiments demonstrating the performance under different channel distortion and channel noise conditions are also included View full abstract»

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  • Performance of fast bandwidth reservation with multipath routing

    Publication Year: 1998 , Page(s): 80 - 86
    Cited by:  Papers (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (668 KB)  

    The authors propose an analysis for computing the burst blocking probability for each end-to-end connection in an ATM network where multipath (MP) routing is used in conjunction with fast bandwidth reservation (FBR). Because single-path (SP) routing is a special case of MP routing, the proposed approach can be used to analyse both routing schemes. Burst blocking probabilities obtained by both simulation and analysis for an eight-node network routing are in good agreement, suggesting that the proposed analysis can be used to obtain a good approximation of the burst blocking probabilities for more complex networks, where computation will be excessive with simulation. The approximate analysis is then used to obtain burst blocking probabilities for MP and SP routings using a more complex network model of 19 nodes. As expected, the blocking performance is generally better with MP routing than with SP routing. However, it is observed that the use of MP routing may cause a small number of end-to-end connections to experience more blockings than they would experience with SP routing, should too much traffic of other connections be overflowing into some of the links they used View full abstract»

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  • FFT-based self-normalising receiver for FFH spread spectrum systems

    Publication Year: 1998 , Page(s): 99 - 104
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (500 KB)  

    Partial-band interference due to intentional and unintentional jamming in fast frequency-hopping spread-spectrum (FFH/SS) systems can be effectively suppressed by additional signal processing techniques. The authors present the performance analysis of a binary frequency-shift-keying SS system in conjunction with a fast Fourier transform (FFT) processor. The FFT-based self-normalising receiver, requiring no knowledge of signal and jamming levels, also enjoys the advantages provided by modern digital signal processing technology. Numerical results show that the receiver performance is better than that of the square-law linear combining receiver and comparable to that of the conventional self-normalising receiver as well as the clipper clipped-linear receiver View full abstract»

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  • Lower bound for multimedia multicast routing

    Publication Year: 1998 , Page(s): 87 - 90
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (412 KB)  

    The optimal multimedia multicast routing problem is to determine a multicast tree of minimal cost to connect a given source node to a given set of destination nodes while fulfilling the delay requirement for multimedia information. This problem has been shown to be NP-complete, and hence fast and good heuristic algorithms must be used in practice for a reasonable network size. The authors derive a lower bound on the cost of the optimal multicast trees by Lagrangean relaxation and problem decomposition. The numerical results for some standard test problems demonstrate that the lower bound is very tight and differs from the optimal solutions by only a few percent on average. In addition, the lower bound can be computed quite quickly and the computation time on a SUN workstation is only a few minutes for the networks with 100 nodes. This tight lower bound can be used to evaluate whether any given heuristic algorithm for multimedia multicast routing is close-to-optimal View full abstract»

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  • (M-1) and (M-2) selfsynchronising M-ary codes generated with coding efficiency

    Publication Year: 1998 , Page(s): 65 - 72
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (788 KB)  

    The presented algorithm can generate two kinds of self-synchronising M-ary variable length codes that are the (M-1) codes and the (M-2) codes, respectively. Each of the constructed codes derived by this algorithm has the self-synchronising property so that the decoder can always reach resynchronisation within a certain number of codewords when an error occurs during transmission. The two kinds of generated M-ary codes are also discussed in terms of the efficiency of resynchronising as well as data compression. The proposed algorithm, which can generate various M-ary codes, actually provides a large variety of choices to create an M-ary variable length code for obtaining data compression while keeping the capability of self-synchronisation when a specific probability distribution of a source is considered View full abstract»

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  • Iterative MAP decoding for serial concatenated convolutional codes

    Publication Year: 1998 , Page(s): 53 - 59
    Cited by:  Papers (4)  |  Patents (2)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (592 KB)  

    The paper provides detailed computational steps for implementing an iterative serial concatenated convolutional code (SCCC) decoder. These are based on maximum a posteriori probability (MAP) decoding of a single, rate 1/2, recursive, systematic convolutional code, which is reduced to easily implemented equations for forward and backward recursion. In particular, the crucial information exchange between MAP decoders is clarified. Simulation of a rate 1/3 SCCC with memory-2 codes and a coding delay of N=1000 shows a bit error rate of 10-6 for Eb/N0=1.5 dB, and gives a typical interleaver gain of N-3 View full abstract»

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