Improving the flare performance of turbo codes using error detection and event flipping

The error rate performance of turbo codes tends to flare at high SNRs due to poor distance properties. It is shown that the flare performance can be significantly improved by using an outer error detection code and a low-complexity event flipping cleanup approach. Using a rate 1/2, single-binary, 4-state turbo code with a 2048-bit data block, the packet error rate at 1.8 dB is lowered from 10^-4 to about 10^-7, with only a small increase in peak decoder complexity. The approach also requires significantly fewer overhead bits than algebraic cleanup codes with hard decoding.