Improved Uplink NOMA Performance Through Adaptive Weighted Factors Aided PIC and MA Signature

Non-orthogonal multiple access (NOMA) is one innovative technology that provides low latency, high system capacity, high spectrum efficiency, and massive connectivity to solve several challenges suffered by a fifth generation (5G) mobile communication system. NOMA on the uplink with superior research value was widely mentioned at Mobile World Congress and has been released in the latest technical report by the Third Generation Partnership Project (3GPP). However, how to decode all users' signals on the uplink NOMA precisely and in parallel and achieve the separation of the superimposed users' signals is the major challenge. Therefore, an improved uplink NOMA scheme through adaptively weighted factors aided parallel interference cancellation (PIC) algorithm and multiple access (MA) signature is proposed to solve the problem. In this paper, we first briefly discuss the research status of the MA signatures used to separate superimposed users' signals. In addition, we review the existing interference cancellation algorithms used by receivers to decode message signals, which mainly include a successive interference cancellation (SIC) algorithm and the PIC algorithm. And the research value of the PIC algorithm on uplink NOMA is highlighted. Then, we briefly formulate the effect of the bias in decision statistics and adaptive weighted factors aided PIC algorithm is proposed to reduce the biased estimation. Finally, yet important, we comprehensively evaluate the performance of the proposed improving PIC algorithm in terms of bit error rate (BER), computational complexity, sum data rate, and delay estimation errors.