On Energy Harvesting of Hybrid TDMA-NOMA Systems

TL;DR

This paper explores a hybrid TDMA-NOMA system that combines energy harvesting and information decoding, optimizing power allocation and splitting ratios to reduce transmit power while meeting user requirements.

Contribution

It introduces a joint design framework for hybrid TDMA-NOMA systems with energy harvesting, addressing non-convex optimization challenges using successive interference cancellation.

Findings

Hybrid TDMA-NOMA outperforms conventional TDMA in transmit power efficiency.

Joint optimization reduces energy consumption while satisfying user rate and energy needs.

Proposed method effectively manages non-convexity in the design problem.

Abstract

In this paper, we investigate energy harvesting capabilities of non-orthogonal multiple access (NOMA) scheme integrated with the conventional time division multiple access (TDMA) scheme, which is referred to as hybrid TDMA-NOMA system. In a such hybrid scheme, users are divided into a number of groups, with the total time allocated for transmission is shared between these groups through multiple time slots. In particular, a time slot is assigned to serve each group, whereas the users in the corresponding group are served based on power-domain NOMA technique. Furthermore, simultaneous wireless power and information transfer technique is utilized to simultaneously harvest energy and decode information at each user. Therefore, each user splits the received signal into two parts, namely, energy harvesting part and information decoding part. In particular, we jointly determine the power allocation and power splitting ratios for all users to minimize the transmit power under minimum rate and minimum energy harvesting requirements at each user. Furthermore, this joint design is a non-convex problem in nature. Hence, we employ successive interference cancellation to overcome these non-convexity issues and determine the design parameters (i.e., the power allocations and the power splitting ratios). In simulation results, we demonstrate the performance of the proposed hybrid TDMA-NOMA design and show that it outperforms the conventional TDMA scheme in terms of transmit power consumption.