Convergence analysis of turbo-hadamard codes using the extrinsic information transfer (EXIT) chart technique

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≈ –1.30 dB, which is about 0.29 dB from the ultimate Shannon limit.