Short binary convolutional codes with maximal free distance for rates 2/3 and 3/4 (Corresp.)

Short binary convolutional codes with maximal free distance for rates 2/3 and 3/4

-A search procedure is developed to find good short binary (N,N 1) convolutional codes. It uses simple rules to discard from the complete ensemble of codes a large fraction whose free distance dfrce either cannot achieve the maximum value or is equal to dfree of some code in the remaining set. Further, the search among the remaining codes is started in a subset in which we expect the possibilit...

Short convolutional codes with maximal free distance for rates 1/2, 1/3, and 1/4 (Corresp.)

This paper gives a tabulation of binary convolutional codeswith maximum free distance for rates s, f, and t for all constraintlengths (measured in information digits) v up to and including v = 14.These codes should be of practical interest in connect ion with Viterbidecoders. A binary convolutional code of rate R = l/n and constraintlength v, measured in information digits, ...

Some long rate one-half binary convolutional codes with an optimum distance profile (Corresp.)

Binary Convolutional Codes of High Rate

The function N(r; ; dfree), defined as the maximum n such that there exists a binary convolutional code of block length n, dimension n r, constraint length , and free distance dfree, is studied. For dfree 2 f3; 4g, codes are obtained from simple constructions that determine N(r; ; dfree) for all positive integers and r. Codes with minimum Hamming distance dfree 5 are found by computer search. A...

Two 16-State, Rate Trellis Codes Whose Free Distances Meet the Heller Bound

For rate R = 1=2 convolutional codes with 16 states there exists a gap between Heller’s upper bound on the free distance and its optimal value. This correspondence reports on the construction of 16state, binary, rate R = 2=4 nonlinear trellis and convolutional codes having dfree = 8; a free distance that meets the Heller upper bound. The nonlinear trellis code is constructed from a 16-state, ra...