Online Backoff Control for NOMA-Enabled Random Access Procedure for Cellular Networks

Abstract

Uplink power domain non-orthogonal multiple access (NOMA) random access (RA) system allows users to transmit their packet with one of target receive power (TRP) levels at the base station (BS). Then the BS can separate the users in simultaneous transmission with successive interference cancellation (SIC), when the users choose different TRP levels. It enjoys a higher throughput through supporting simultaneous transmissions that occur frequently in RA system. This letter examines how to incorporate uplink NOMA RA system with the existing Long-Term Evolution (LTE) RA procedure with minimal modifications. Furthermore, to optimize the proposed RA procedure, we propose an online control algorithm for backoff interval and analyze its performance particularly with focus on the average RA delay. The results show that the proposed RA procedure achieves 0.5896L of throughput for a total of L RA preambles and guarantees the average RA delay by 1/(0.5896L-lambda) for Poisson traffic with mean lambda.