Residual frequency offset compensation-embedded turbo decoder

We propose a modified iterative turbo decoder, which inherently compensates the residual frequency offset remained in the decoder input. Based on the recently proposed phase offset compensation scheme which embeds phase compensation into iterative turbo decoding, we extend it to cover up to the frequency offset compensation. At each iteration, we estimate the residual frequency offset remained in the soft decoder output and compensate it for the next iteration. As iteration goes on, frequency offset is gradually and drastically reduced. Consequently, the severe turbo decoding failure due to even small residual frequency offset can be significantly recovered and then, almost the ideal decoding performance is achieved. Especially for power limited communications under very low SNR environment where the even tiny frequency offset is critical to turbo decoding, the proposed scheme is efficient since it does not require additional transmission power for compensation.