Improving Error Resiliency of Sparse Code Multiple Access Using Precoding and Non-orthogonal Signaling Techniques

Abstract

The high data rate and seamless connectivity requirements in cellular networks make it necessary to explore key-enabling technologies for next generation (5G) wireless communication networks. Recent studies in 5G physical layer technologies consider the use of non-orthogonal multiple access and non-orthogonal signaling techniques as means to achieve better spectral efficiency at an acceptable link level performance. In this paper, a new multi-user transmission scheme is presented which combines Sparse Code Multiple Access (SCMA), a non-orthogonal multiple access technique that exploits codeword sparsity, with a non-orthogonal multicarrier signal that uses precoding and tight subcarrier packing schemes. The study assesses the impact of bandwidth compression and iterative decoding complexity on the bit error rate (BER) performance of the system. Modeling is done in simple Gaussian noise channels and channels experiencing independent frequency-flat Rayleigh fading per sample. Simulation results are provided showing that proposed transmission scheme can achieve better error resiliency while maintaining the spectral efficiency of conventional SCMA.