Hybrid NOMA Assisted OFDMA Uplink Transmission

TL;DR

This paper investigates hybrid NOMA combined with OFDMA for uplink transmission, analyzing its performance benefits and energy efficiency, especially considering users' dynamic channel information, and introduces new metrics for performance evaluation.

Contribution

It is the first to analyze hybrid NOMA with OFDMA in uplink, revealing its advantages over pure OMA and TDMA, and introduces new performance metrics like power outage probability and power diversity gain.

Findings

Hybrid NOMA with OFDMA rarely adopts pure OMA mode.

Pure NOMA can minimize users' energy consumption.

Hybrid NOMA improves performance metrics such as power outage probability.

Abstract

Hybrid non-orthogonal multiple access (NOMA) has recently received significant research interest due to its ability to efficiently use resources from different domains and also its compatibility with various orthogonal multiple access (OMA) based legacy networks. Unlike existing studies on hybrid NOMA that focus on combining NOMA with time-division multiple access (TDMA), this work considers hybrid NOMA assisted orthogonal frequency-division multiple access (OFDMA). In particular, the impact of a unique feature of hybrid NOMA assisted OFDMA, i.e., the availability of users' dynamic channel state information, on the system performance is analyzed from the following two perspectives. From the optimization perspective, analytical results are developed which show that with hybrid NOMA assisted OFDMA, the pure OMA mode is rarely adopted by the users, and the pure NOMA mode could be optimal for minimizing the users' energy consumption, which differs from the hybrid TDMA case. From the statistical perspective, two new performance metrics, namely the power outage probability and the power diversity gain, are developed to quantitatively measure the performance gain of hybrid NOMA over OMA. The developed analytical results also demonstrate the ability of hybrid NOMA to meet the users' diverse energy profiles.