Asymmetric Adaptive Modulation for Uplink NOMA Systems

Non-orthogonal multiple access (NOMA) as a promising technology, can achieve enhanced connectivity and spectral efficiency. However, the asymmetric channels in uplink NOMA systems can bring distinct uncertainty of the bit error rate (BER) and throughput performances to the users. To address this problem, an asymmetric adaptive modulation (AAM) framework for uplink NOMA systems is introduced in this paper. We first derive the closed-form BER expressions for uplink NOMA systems, then we propose a principle for reducing the performance uncertainty. Finally, we develop an AAM algorithm for uplink NOMA systems by studying the closed-form BER expressions. Numerical results demonstrate the correctness of the BER expressions we derived, and show that our AAM algorithm outperforms the benchmark in terms of the system sum throughput.

Automated summary

This paper introduces an asymmetric adaptive modulation (AAM) framework for uplink NOMA systems, develops an AAM algorithm by studying closed-form BER expressions and reducing performance uncertainty, and shows that the AAM algorithm outperforms the benchmark in terms of system sum throughput.