Energy Efficiency Fairness Beamforming Designs for MISO NOMA Systems

Haitham Al-Obiedollah,Jeyarajan Thiyagalingam,Kanapathippillai Cumanan,Octavia A Dobre,Alister G Burr,Zhiguo Ding

doi:10.1109/wcnc.2019.8886009

Abstract

In this paper, we propose two beamforming designs for a multiple-input single-output non-orthogonal multiple access system considering the energy efficiency (EE) fairness between users. In particular, two quantitative fairness-based designs are developed to maintain fairness between the users in terms of achieved EE: max-min energy efficiency (MMEE) and proportional fairness (PF) designs. While the MMEE-based design aims to maximize the minimum EE of the users in the system, the PF-based design aims to seek a good balance between the global energy efficiency of the system and the EE fairness between the users. Detailed simulation results indicate that our proposed designs offer many-fold EE improvements over the existing energy-efficient beamforming designs.

Highlights

Non-orthogonal multiple access (NOMA) has been recently envisioned as a promising multiple access technique to be used in future wireless networks for addressing the issue of low spectral efficiency in conventional orthogonal multiple access (OMA) and to provide massive connectivity [1]
We introduce a new set of slack variables δi and τi to approximate the non-convex constraint in (22a) as log(1 + signalto-interference plus noise ratio (SINR)(ki)) ≥ δi, ∀i ∈ K, k ≤ i, (1 + SINR(ki)) ≥ τi, ∀i ∈ K, k ≤ i, (24a) (24b) which can be equivalently represented as the following set of constraints:
We proposed two beamforming designs for a multipleinput single-output (MISO) NOMA system considering the EE fairness between users

Summary

Introduction

Non-orthogonal multiple access (NOMA) has been recently envisioned as a promising multiple access technique to be used in future wireless networks for addressing the issue of low spectral efficiency in conventional orthogonal multiple access (OMA) and to provide massive connectivity [1] In this novel multiple access scheme, multiple users share the same orthogonal resources (i.e., time, frequency and spreading codes) by exploiting power-domain multiplexing [2]. The users with weaker channel conditions (i.e., cell-edge users) might achieve a very low EE compared to those users with stronger channel conditions (near users) To overcome such a fairness issue among the users, the transmitter should be able to incorporate the performance of the individual users in the design rather than optimizing the GEE of the system. While there is no unique definition for fairness, this could be generally defined in terms of allocating the resources between the users to provide a reasonable qualityof-service at all of them [11]

Methods

Results

Conclusion