Iterative Decoding of Superposition Coding

Clipping is applied to superposition coding systems to reduce the peak-to-average power ratio (PAPR) of the transmitted signal. The performance limit is investigated through evaluating the mutual information driven by the induced peak-power-limited input signals. It is shown that the channel capacity can be approached by clipped superposition coding systems. To alleviate the performance degradation due to clipping noises, we develop a soft compensation algorithm that is combined with soft-input-soft-output (SISO) decoding algorithms in an iterative manner. Simulation results show that with the proposed algorithm, most performance loss can be recovered.