EXPLOITING THE CANNIBALISTIC TRAITS OF REED-SOLOMON CODES

In Reed-Solomon codes and all other maximum distance separable codes t here is an intrinsic relationship between the size of the symbols in a codeword and the length of the codeword. Increasing the number of sym bols in a codeword to improve the efficiency of the coding system thus requires using larger symbols. However, big Reed-Solomon codes are di fficult to implement and many communications or storage systems cannot easily accommodate an increased symbol size, e.g., M-ary FSK and phot on counting pulse position modulation demand a fixed symbol size. This paper describes a technique for sharing redundancy among many differe nt Reed-Solomon codewords to achieve the efficiency attainable in long Reed-Solomon codes without increasing the symbol size. The paper pres ents techniques both for calculating the performance of these new code s and for determining their encoder and decoder complexities. These co mplexities are usually substantially lower than conventional Reed-Solo mon codes of similar performance.