Power Allocation for a HAPS-Enabled MIMO-NOMA System with Spatially Correlated Channels

TL;DR

This paper explores power allocation in a HAPS-enabled MIMO-NOMA system, leveraging spatially correlated channels to enhance data rates and energy efficiency in 6G networks.

Contribution

It introduces a novel power allocation algorithm that groups users based on channel correlation to optimize system performance.

Findings

HAPS systems outperform terrestrial BS in data rate and energy efficiency.

The proposed algorithm effectively maximizes total rate under QoS and SIC constraints.

Utilizing spatial correlation improves user grouping and system performance.

Abstract

High-altitude platform station (HAPS) systems are considered to have great promise in the multi-tier architecture of the sixth generation (6G) and beyond wireless networks. A HAPS system can be used as a super macro base station (SMBS) to communicate with users directly since there is a significant line-of-sight (LoS) link between a HAPS and terrestrial users. One of the problems that HAPS SMBS systems face, however, is the high spatial correlation between the channel gain of adjacent users, which is due to the LoS link between the HAPS and terrestrial users. In this paper, in addition to utilizing the spatial correlation of channel gain between multiple users to improve user services, we consider correlated channel gain for each user. In the proposed method, terrestrial users with a high spatial correlation between their LoS channel gain are grouped into NOMA clusters. Next, an algorithm is proposed to allocate power among terrestrial users to maximize the total rate while satisfying the quality-of-service (QoS) and successive interference cancellation (SIC) conditions. Simulation results show that a HAPS SMBS has superior data rate and energy efficiency in comparison to a terrestrial BS.