In this study, an integer programming approach is introduced to construct unequal error protection (UEP) codes for a multiuser broadcast communication system. The authors establish integer programming models for both binary and non‐binary UEP codes. The results show that optimal UEP codes can be constructed such that their code lengths achieve the integer programming bounds. Based on the bounds, the authors investigate asymptotic behaviour of code rates with symbols in 𝔼𝔼( q ), and the authors present performance analysis of multiuser communications over a degraded broadcast channel with the optimal UEP codes.

In this paper, a class of product codes based on low-density parity check (LDPC) constituent codes are constructed for multiple phased-burst erasure correction (MPBEC). These codes are shown to correct one large burst and/or a number of shorter bursts. A simple novel recursive erasure correction algorithm is proposed based on a recently discovered zero-span approach to linear block code analysis that can produce very powerful MPBEC capabilities. Analysis and data on how these codes work for additive white Gaussian noise (AWGN) channel are also presented.

In this paper we introduce puncturing techniques to produce high-rate π-rotation low-density parity-check (LDPC) codes. The techniques rely on symmetry considerations to maintain simple description and to achieve excellent performance. We also extend the bounds on the minimum d2for the high-rate codes.

Novel coding schemes for noiseless and noisy asynchronous code division multiple access (A-CDMA) systems are presented in this paper. The schemes use Wu-Chang spreading code, block interleaver, and synchronizable channel codes to support A-CDMA communications with random delays. For the noiseless case, each active user generates one of M messages, M = ⌊(2T-D-1)/(D + 1)⌋ , and a (T-D)-stage MLSR encoder encodes the message into a codeword of length T. Given a maximum random delay of D chips, the receiver can decode messages of all active users without ambiguity. For the noisy case, extended Bose-Caldwell cyclic codes are used to encode messages. The extended cyclic codes provide error correction and delay recovery effectively. By using a BCH code of lengthnas the cyclic code, the extended code can correct up to τ ≤ ⌊n/4⌋ errors and recover a maximum random delay of n -1 chips.

We present irregular /spl pi/-rotation LDPC codes by extending the classic /spl pi/-rotation parity check matrix to allow irregular column weight and choice of many code rates. The irregular /spl pi/-rotation codes are defined with a small set of parameters providing the exact definition of the code with its performance. The encoding circuit is based on the original /spl pi/-rotation design and thus users have the choice of using regular or irregular matrix patterns and various code rates without changing the encoding circuitry. We compare the performance of the irregular /spl pi/-rotation code against the binary Shannon limit for several rates.

We present a framework for designing a class of concatenated codes based on low-density parity-check component codes that we call parallel concatenated Gallager codes (PCGC). The iterative decoding trajectories technique is used to explain the performance of PCGC. Simulation results show an enhanced performance in the practical E/sub b//N/sub 0/ range in both AWGN and flat Rayleigh fading channels. The reduced decoding complexity of the proposed coding scheme along with its good performance makes it an attractive candidate in delay sensitive applications.

We present a class of concatenated codes called parallel concatenated Gallager codes (PCGC) using low-density parity-check (LDPC) component codes. We report simulation results for PCGC that outperform those for comparable LDPC codes both in additive white Gaussian noise (AWGN) and flat Rayleigh fading channels. The good performance of PCGC increases the capacity of CDMA systems while the reduced encoding and decoding complexity of such codes keep the signal processing delays within a reasonable limit.

We introduce an ensemble of quasi-regular low-density parity check error control codes we call /spl pi/-rotation LDPC codes. These codes are completely defined by a single permutation vector of length n/8 where n is the length of the code. We present an efficient encoding scheme and circuit design based on the single permutation. Simulation results indicate that these codes perform as well as regular low density parity check codes based on completely random matrix constructions. These features make the /spl pi/-rotation code valuable for practical communication system implementation.

This correspondence presents a new coding scheme based on a combinatory detecting set for synchronous code-division multiple-access (S-CDMA) systems, which can support a number of users far exceeding current S-CDMA approaches. Examples of code construction and decoding are also given.

Coding schemes for the noiselessT-user binary adder multiple-access channel are discussed. A class of uniquely decodable codes of arbitrary length satisfying a specific recursive relationship and which are asymptotically good is explicitly constructed.

Two specific noiseless multiple-access channel models, theT-userM-frequency multiple-access channel with and without intensity information, are studied in this paper. Information-theoretic bounds on the transmission rate for both models are presented. Constructive coding schemes are given for both channels which achieve zero error probability and whose rate sum is close to the information-theoretic bounds. Although the problem is formulated in terms of frequencies, the results are applicable to any signaling scheme where M orthogonal signals are used in each signaling interval including time partitioning of the interval.

A simple derivation is given of the MacWilliams' identity relating the weight distribution of the codewords in a linear code and the weight distribution of the dual code. The derivation is based upon elementary probabilistic arguments.

Coding schemes for the binary memorylessT-user adder channel are investigated in this paper. First upper and lower bounds on the capacity sum, which are asymptotically tight with increasingT, are derived for the noiseless case. Second, a class ofT-user uniquely decodable codes with rates, asymptotically inT, equal to the maximal achievable values is constructed. A decoding algorithm for these codes is also presented. Next, a class of error-correcting codes for the noisyT-user adder channel is constructed. It is shown that these codes can he used to construct multilevel codes suitable for use on the additive white Gaussian noise channel.