Resource Allocation for NOMA Based OTFS Transmission with Heterogeneous Mobility Users

Abstract

This paper investigates the reliability performance of the non-orthogonal multiple access (NOMA) based orthog-onal time frequency space (OTFS) system, namely NOMA-OTFS, where both high-mobility and low-mobility users coexist. To minimize the average bit error rate (BER), we formu-late the resource allocation for the downlink NOMA-OTFS transmission, where the user pairing, transmit power, and resource blocks are jointly optimized. To solve this mixed integer programming problem, we first develop the power allocation scheme in the scenario of only two users, then apply it to the general case and obtain the scheme of user pairing and resource block allocation by a proposed near-optimal NOMA users and resource blocks three-sided matching alogrithm (URMA). The simulation results demonstrate that the proposed algorithm significantly outperforms the random matching method and greedy algorithm, and its performance is very close to the optimal exhaustive method.