For an error-correcting code and a distance bound, the list decoding problem is to compute all the codewords within a given distance to a received message. The boundeddistancedecoding problem is to find one codeword...
详细信息
For an error-correcting code and a distance bound, the list decoding problem is to compute all the codewords within a given distance to a received message. The boundeddistancedecoding problem is to find one codeword if there is at least one codeword within the given distance, or to output the empty set if there is not. Obviously the boundeddistancedecoding problem is not as hard as the list decoding problem. For a Reed-Solomon code [n, k](q), a simple counting argument shows that for any integer 0 < g < n, there exists at least one Hamming ball of radius n-g, which contains at least ((n)(g))/q(g-k) many codewords. Let (g) over cap (n, k, q) be the smallest positive integer g such that (g(n))/q(g-k) <= 1. One knows that k - 1 <= (g) over bar (n, k, q) <= root n(k-1) <= n. For the distance bound up to n - root n(k - 1), it is known that both the list and boundeddistancedecoding can be solved e. ciently. For the distance bound between n- root n(k - 1) and n-(g) over bar (n, k, q), we do not know whether the Reed - Solomon code is list or boundeddistance decodable;nor do we know whether there are polynomially many codewords in all balls of the radius. It is generally believed that the answer to both questions is no. In this paper, we prove the following: ( 1) List decoding cannot be done for radius n-(g) over cap (n, k, q) or larger, unless the discrete logarithm over F-q (g) double under bar (n,F- k,F- q)- k is easy. (2) Let h and g be positive integers satisfying q >= max(g(2), (h - 1)(2+is an element of)) and g = (4/is an element of + 2)(h+1) for a constant is an element of > 0. We show that the discrete logarithm problem over F-q(h) can be e. ciently reduced by a randomized algorithm to the boundeddistancedecoding problem of the Reed-Solomon code [q, g-h](q) with radius q - g. These results show that the decoding problems for the Reed-Solomon code are at least as hard as the discrete logarithm problem over certain finite fields. For the list decoding proble
For an error-correcting code and a distance bound, the list decoding problem is to compute all the codewords within a given distance to a received message. The boundeddistancedecoding problem is to find one codeword...
详细信息
For an error-correcting code and a distance bound, the list decoding problem is to compute all the codewords within a given distance to a received message. The boundeddistancedecoding problem is to find one codeword if there is at least one codeword within the given distance, or to output the empty set if there is not. Obviously the boundeddistancedecoding problem is not as hard as the list decoding problem. For a Reed-Solomon code [n, k](q), a simple counting argument shows that for any integer 0 < g < n, there exists at least one Hamming ball of radius n-g, which contains at least ((n)(g))/q(g-k) many codewords. Let (g) over cap (n, k, q) be the smallest positive integer g such that (g(n))/q(g-k) <= 1. One knows that k - 1 <= (g) over bar (n, k, q) <= root n(k-1) <= n. For the distance bound up to n - root n(k - 1), it is known that both the list and boundeddistancedecoding can be solved e. ciently. For the distance bound between n- root n(k - 1) and n-(g) over bar (n, k, q), we do not know whether the Reed - Solomon code is list or boundeddistance decodable;nor do we know whether there are polynomially many codewords in all balls of the radius. It is generally believed that the answer to both questions is no. In this paper, we prove the following: ( 1) List decoding cannot be done for radius n-(g) over cap (n, k, q) or larger, unless the discrete logarithm over F-q (g) double under bar (n,F- k,F- q)- k is easy. (2) Let h and g be positive integers satisfying q >= max(g(2), (h - 1)(2+is an element of)) and g = (4/is an element of + 2)(h+1) for a constant is an element of > 0. We show that the discrete logarithm problem over F-q(h) can be e. ciently reduced by a randomized algorithm to the boundeddistancedecoding problem of the Reed-Solomon code [q, g-h](q) with radius q - g. These results show that the decoding problems for the Reed-Solomon code are at least as hard as the discrete logarithm problem over certain finite fields. For the list decoding proble
A coset representation of the bit error probabilities for binary linear block codes and arbitrary symmetric memoryless channels is derived. Such a representation leads to simple upper bounds on the bit error probabili...
详细信息
ISBN:
(纸本)0780376293
A coset representation of the bit error probabilities for binary linear block codes and arbitrary symmetric memoryless channels is derived. Such a representation leads to simple upper bounds on the bit error probabilities for code components expressed via 2n code spectra, where n is the code length, and to a "boundeddistancedecoding" algorithm. The performance of the algorithm is illustrated for the (23,12) Golay code and a particular channel having non-binary output alphabet where it attains a sub-optimum performance.
暂无评论