A PAPR-Reduction SCMA Codebook Design for Satellite Communication Systems

Abstract

Sparse code multiple access (SCMA), as a promising multiple access scheme suggested for the fifth generation (5G)wireless networks, can achieve higher user capacity. In this paper, we consider the SCMA technique for low earth orbit (LEO)satellite communication systems to improve user capacity and support massive connection for satellite Internet of Things (IoT). Note that, high peak-to-average power ratio (PAPR)is a tough challenge for SCMA-based LEO satellite downlink systems due to its power-limited property. Thus, an optimized codebook design based on the traditional codebook is proposed to reduce the PAPR. Firstly, the signal points with large power are reassigned to construct a low-PAPR mother constellation. Then, the constellation rotations of users colliding in a resource are jointly designed to further reduce the PAPR. Numerical results show that the designed codebook in an LDPC coded SCMA system can achieve lower PAPR while maintaining better performance and lower complexity than the traditional codebook.