Turbo-Coded OFCDM Systems for 4G Mobile Communications

In this paper, a hybrid multicode interference cancellation (MCI) and minimum mean square error (MMSE) detection scheme is presented for the turbo-coded orthogonal frequency and code division multiplexing (OFCDM) systems. The weights of hybrid detection are derived theoretically and an effective method to generate the weights in practical applications is proposed. By means of computer simulation, it is shown that to carry out interference regeneration for the hybrid detection, the conventional turbo decoding algorithm should be extended to decode parity bits as well. Moreover, two iterations in turbo decoding are sufficient to provide good performance for the system with the multistage hybrid detection. Finally, the proposed method for MMSE weight estimation works well with properly chosen parameters.