Citation
Abstract
A method for obtaining the complete path enumerator T(D, L,I) of a convolutional code is described. A system of algebraic equations is solved, using a new algorithm for computing determinants, to obtain T(D, L,I) for the (7,1/2) NASA standard code. Generating functions, derived from T(D,L,I), are used to upper bound Viterbi decoder error rates. This technique Is currently feasible for constraint length K < 10 codes. A practical, fast algorithm is presented for computing the leading nonzero coefficients of the generating functions used to bound the performance of constraint length K < 20 codes. Code profiles with about 50 nonzero coefficients are obtained with this algorithm for the experimental K = 15, rate 1/4, code in the Galileo mission and for the proposed K = 15, rate 1/6, “2-dB” code.
Details
- Volume
- 42-100
- Published
- February 15, 1990
- Pages
- 203–213
- File Size
- 482.1 KB