Clipping Can Improve the Performance of Spatially Coupled Sparse Superposition Codes

Gaussian signaling of spatially coupled sparse superposition codes incurs a high peak-to-average-power ratio (PAPR) problem. Clipping can be used to reduce PAPR. At the receiver side, generalized approximate message passing algorithm is employed to handle the non-linear clipping distortion. Surprisingly, we observe empirically that clipping can improve the performance in low-to-medium rate region. We provide an explanation of this observation based on potential function analysis.