Showing papers on "List decoding published in 1985"
TL;DR: Random codes for the arbitrarily varying channel are investigated, where a quantity called key rate is used as a measure of the rate of increase.
Abstract: Random codes for the arbitrarily varying channel are investigated The code ensemble is restricted to increase only exponentially with codeword length; a quantity called key rate is used as a measure of the rate of increase The reliability function for such codes is related to the reliability function for codes with unlimited key rate Explicit results are obtained in some examples of practical interest
144 citations
TL;DR: In this article, a universal decoding procedure for finite-state channels is proposed, which achieves an error probability with an error exponent that, for large enough block length, is equal to the random coding error exponent associated with the optimal maximum likelihood decoding procedure.
Abstract: Universal decoding procedures for finite-state channels are discussed. Although the channel statistics are not known, universal decoding can achieve an error probability with an error exponent that, for large enough block length (or constraint length in case of convolutional codes), is equal to the random-coding error exponent associated with the optimal maximum-likelihood decoding procedure for the given channel. The same approach is applied to sequential decoding, yielding a universal sequential decoding procedure with a cutoff rate and an error exponent that are equal to those achieved by the classical sequential decoding procedure.
126 citations
TL;DR: The proposed choice of the coset leaders allows for the classes of uniformly packed and nearly perfect binary codes to achieve a lower information bit error probability, at least for p sufficiently near zero.
Abstract: Complete decoding of systematic linear block codes by standard arrays with coset leaders not necessarily of minimal weight gives, in several interesting cases on the binary symmetric channel with error probability p , a smaller symbol error probability than decoding using the coset leaders of minimum weight. The proposed choice of the coset leaders allows for the classes of uniformly packed and nearly perfect binary codes to achieve a lower information bit error probability, at least for p sufficiently near zero.
9 citations
Patent•
29 May 1985
TL;DR: In this paper, an apparatus for decoding compressed image codes ensures exact synchronization of decoded image signals by differentiating the decoding process in response to the detection of a particular code, which is a technique similar to the one described in this paper.
Abstract: An apparatus for decoding compressed image codes ensures exact synchronization of decoded image signals by differentiating the decoding process in response to the detection of a particular code.
7 citations
TL;DR: An erasure-control decoding algorithm is discussed for frequency-hopped spread-spectrum systems operating in the presence of pulsed or partial-time interference, and some properties of the resulting error probability which are useful in designing effective decoding algorithms are derived.
Abstract: An erasure-control decoding algorithm is discussed for frequency-hopped spread-spectrum systems operating in the presence of pulsed or partial-time interference, and some properties of the resulting error probability which are useful in designing effective decoding algorithms are derived. Based on numerical results, specific decoding algorithms which correct both erasures and errors are then presented for use with block codes employing hard decisions.
7 citations
DOI•
01 Apr 1985TL;DR: The error-trellis syndrome decoding method applied to this example shows in detail how much more efficient syndrome decoding is than, say, Viterbi decoding would be if applied to the same problem.
Abstract: In the paper, a new error-trellis syndrome decoding technique for convolutional codes is developed. This algorithm is specialised then to the entire class of systematic convolutional codes. Finally, this algorithm is applied to the high-rate Wyner-Ash convolutional codes. A special example of the one-error-correcting Wyner-Ash code, a 3/4 rate code, is treated in the paper. The error-trellis syndrome decoding method applied to this example shows in detail how much more efficient syndrome decoding is than, say, Viterbi decoding would be if applied to the same problem. For standard Viterbi decoding, 64 states would be required, whereas in the example only seven states are needed. Also, within the seven states required for decoding, many less transitions are needed between the states.
4 citations
01 Jan 1985
TL;DR: There is a continuing requirement to devise simpler and more effective decoding algorithms to exploit as much as possible any sturcture which exists in the code.
Abstract: The decoder for an error-correcting code is, in almost all cases of interest, several orders of magnitude more complex than the corresponding encoder. So the selection of a code is in practice usually determined by the choice of decoding method, rather than the other way round. Possible decoding methods are determined by the constraints of the information transmission, storage or processing system: which requires protection against errors; the code selected will be the one which offers the highest error-control capability from among those codes which can be decoded cost-effectively within the system constraints. A simpler decoding method will, other things being equal, permit the use of a more powerful error-control code; thus there is a continuing requirement to devise simpler and more effective decoding algorithms. One way to achieve this is to exploit as much as possible any sturcture which exists in the code; several ways of doing this are reviewed and presented in this contribution.
4 citations
TL;DR: The generalized threshold decoding of cyclic codes is a generalization for the threshold decoding and the modified error-trapping decoding, and it combines their advantages and is more efficient than the permutation decoding.
3 citations
TL;DR: A decoding algorithm for linear codes is presented, which is able to correct beyond the half minimum distance and which has the capability to include soft decision decoding.
Abstract: A decoding algorithm for linear codes is presented, which is able to correct beyond the half minimum distance and which has the capability to include soft decision decoding. Results on applying this algorithm to some codes (with and without soft decision) are included.
21 May 1985
TL;DR: It is shown that the increased error correction capability can be realised and that useful performance improvements are gained.
Abstract: Soft decision decoding offers the possibility of correcting data errors beyond the hard decision capability of a code. The application of soft decision decoding to the mobile radio data channel has been investigated. The performance of random error and burst error correcting algorithms on a Rayleigh fading channel has been measured. It is shown that the increased error correction capability can be realised and that useful performance improvements are gained.
TL;DR: Numerical comparisons show that the proposed adaptive decoding method achieves a better decoding performance, and even if some quality degradation is unavoidable, communication that is as good as possible is achieved even when the communication channel is in a bad condition.
Abstract: A general decoding method for doubleencoding systems has been proposed by Imai and Nagasaka, wherein decoding state information obtained in the first stage is utilized fully. This method has a better decoding performance than conventional ones and implementation is easy. However, because this method is based on the probabilistic characteristic of communication channel, its decoding performance can deteriorate when BER of communication channel is varied. This paper proposes an adaptive decoding method which follows the variation of probabilistic characteristic of communication channel. In this method, channel state information can be obtained in the first stage, then the second decoding stage is performed appropriately to that channel state information. With this proposed method, high quality communication is achieved when the communication channel is in good condition. Moreover, even if some quality degradation is unavoidable, communication that is as good as possible is achieved even when the communication channel is in a bad condition. Since an enormous amount of computation is necessary to determine the optimum adaptive decoding system, an adaptive decoding method using some approximation is studied. This method is suitable for a channel where transitions of the channel states can be modeled as a Markov process. Numerical comparisons show that the proposed method achieves a better decoding performance.