Research On Resource Scheduling And Power Allocation Algorithms For Sparse Code Multiple Access System

Sparse code multiple access(SCMA)is a new type of non-orthogonal multiple access technology,and it originates from low-density signature(LDS)technology.SCMA can obtain an additional coding gain through the codebook design.Combining the concepts of OFDMA and CDMA,SCMA has the advantages of high capacity,low time delay and high transfer rate.This article is divided into three parts to discuss on SCMA system related issues.Firstly,we introduce the basic principle of SCMA and present a typical SCMA system link-level model.SCMA transmitter design and coding techniques can be divided into two modules,including multi-dimensional modulation and sparse sequence spread spectrum,and the matching relationship between resource and users is analyzed.Then the SCMA receiver design and decoding techniques are introduced,including the decoding scheme based on the maximum likelihood algorithm and the decoding scheme based on the message passing algorithm.Through the analysis of these basic theories for the subsequent further study of SCMA technology laid the foundation.Secondly,three kinds of classical resource scheduling algorithms and three real-time service resource scheduling algorithms are introduced.Then,adaptive overloading technology is proposed based on adaptive modulation and coding technology,and adaptive SCMA system is designed.Compared to OFDMA and SCMA systems,the adaptive SCMA system has better flexibility and adaptability,but its inherent resource block fragmentation problem directly affects the system performance.To solve this problem,this paper designs two feasible resource schedule schemes: User grouping scheme and sequential optimization scheme.The theoretical derivation and simulation results prove the superiority of the proposed algorithm and scheme.Finally,for the SCMA downlink,the power allocation scheme based on capacity maximization and energy efficiency maximization are proposed for the two goals of system capacity and system energy efficiency.At the same time,combined with the characteristics of SCMA,the proposed power allocation scheme can be divided into three levels: single-user carrier power allocation,power allocation between users within a group and power allocation between groups.Finally,the validity of the proposed scheme is proved by simulation results.