Enhancement of turbo codes using cyclic redundancy check with interleaver optimisation

A method is presented where a parallel concatenated convolutional code is preceded with a short cyclic redundancy check (CRC) without code rate loss. Parity bits are punctured and their place taken by the CRC. Results are given for the weight spectrum of an optimised code, rate 2/3, codeword length, n=1014 in comparison with an optimised, nonCRC code using the same rate and codeword length. Frame error rate performance achieved is within 0.36dB of the sphere packing bound constrained for binary transmission.