Reduced-complexity decoding for concatenated codes based on rectangular parity-check codes and turbo codes

We compare the performance of several different decoding strategies for concatenated codes based on a serial concatenation of a rectangular parity-check code (RPCC) with a turbo code. These concatenated codes are referred to as RPCC+turbo codes. RPCC+turbo codes have been shown to outperform turbo codes significantly in several scenarios (see Shea, J.M., Proc. 2001 IEEE Int. Symp. Information Theory, p.144, 2001; Shea and Wong, T.F., Proc. 2001 IEEE Military Commun. Conf., 2001). One particularly useful application is to replace a turbo code with an RPCC+turbo code based on constituent codes of smaller memory. This combination can provide comparable or better performance while also achieving a lower decoder complexity (see Shea and Wong, 2001). However, the complexity of the iterative MAP decoder for such a code is still relatively high. We compare several different decoding strategies for the RPCC+turbo code that offer various trade-offs between performance and complexity