Performance analysis of codebook design using SCMA scheme based on An and Dn lattices for 5G communications

Abstract

Sparse Code Multiple Access (SCMA) is a Non-Orthogonal Multiple newlineAccess (NOMA) scheme that is used to manage the uplink component of 5G newlinecommunications networks. The ability to handle more users is a requirement newlinefor 5G cellular networks. To address this, SCMA enables each user to newlinebroadcast multiple subcarriers, enabling multiple users to contribute to the newlinesame frequency using superposition coding. To increase channel efficiency newlineand better manage the available frequency spectrum, the SCMA approach is newlineused in conjunction with codebook design for each user. SCMA still has newlineunresolved problems with large-scale codebook set design. Multi-dimensional newlineconstellation mapping in SCMA systems plays a significant role in enhancing newlinesystem performance with the improved encoding and decoding technology of newline5G networks. In this work to improve the performance of the SCMA uplink newlinesystem, a codebook designed with lattice concepts is proposed. The codebook newlineis designed using popular lattices as a basis, such as An and Dn. A collection newlineof 2D real constellations obtained by lattice theory, which has an enormous newlinecoding gain and infinite points, is used to implement multidimensional newlinecomplex mother constellation designs. Lattice-based codebooks are designed newlineby combining the mother constellations and the mapping matrix with newlineconstellation rotation. The simulation results show that the proposed newlinecodebooks can significantly lower the Bit Error Rate (BER) value under newlinevarious channels and codebook sizes when compared to the existing newlinecodebooks. The performance of the large-scale SCMA codebook has also newlinebeen improved in the proposed lattice-based codebook. In order to take newlineadvantage of the strong iterative decoding performance, SCMA is typically newlineimplemented at the decoder with the Message Passing Algorithm (MPA). newline