On the limiting performance of turbo-Hadamard codes

In this letter, we employ the extrinsic information transfer (EXIT) chart technique to assess the limiting performance of turbo-Hadamard codes and identify the optimized design parameters for such codes. It is shown that for a sufficiently long code length and a sufficiently large number of iterations, a carefully designed low rate turbo-Hadamard code can potentially achieve successful decoding at E_b/N₀≈-1.3 dB, which is about 0.29 dB from the ultimate Shannon limit.