A robust decoder for distributed turbo codes in relay channel

In this paper, a decoder based on log-MAP (maximum a-priori) algorithm for distributed turbo codes in relay channel is designed. The structure of the proposed turbo decoder is similar to the standard turbo iterative decoder with two soft-input soft-output (SISO) modules. However, the inputs to the decoder as well as the extrinsic signals between the two SISO modules are differently calculated. The principle of the proposed decoder is to get inputs to each SISO module that comes from one specific transmitter. Simulation results show that the proposed decoder has faster convergence and better BER performance than the standard decoder when the input from source and relay are with mismatched signal strength. The proposed decoder is also robust against this signal quality mismatch.