Analysis of the Spectral Performance of Non-Orthogonal Multiple Access (NOMA)

Abstract

This thesis presents the theoretical analysis on the spectral performance of non-orthogonal multiple access (NOMA) for downlink communication. Based on accurate evaluation, previous researchers in this field, i.e. P. Sedtheetorn and T. Chulajata, proposed a closed form expression of NOMA downlink spectral efficiency, which is used to obtain analytical results in this thesis. With the closed form expression, the exact average of NOMA spectral efficiency is achieved at different key system parameters. In terms of channel modelling, the channel conditions are mapped with Nakagami, Rayleigh, and AWGN models in which both line-of-sight (LOS) and non-line-of-sight (NLOS) are included. We extend our work to the case of random active users. The proposed expression by recent researchers, i.e. P. Sedtheetorn and T. Chulajata, is very comprehensive and benefits us to study the impact of channel conditions, user density, and other key system parameters on the NOMA spectral efficiency. Moreover, this closed form expression can be used to evaluate other orthogonal multiple access (OMA) techniques such as orthogonal frequency division multiple access (OFDMA). Numerical results are provided to render the theoretical analysis valid and show the impact of the major system parameters on the spectral performance of NOMA.