# On the Outage Probability of Multiuser Multiple Antenna Systems with Non-Orthogonal Multiple Access for Air-Ground Communications

## TL;DR

This paper analyzes the outage probability in multiuser MIMO systems with NOMA for air-ground communications, demonstrating that joint group decoding can significantly improve spectral efficiency and reduce outages in realistic aeronautical channels.

## Contribution

It introduces a stochastic AG channel model for outage analysis and compares three decoding strategies, highlighting the benefits of joint group decoding in NOMA systems.

## Key findings

- Joint group decoding greatly reduces outage probability.
- Non-orthogonal multiple access enhances spectral efficiency in aeronautical channels.
- Decoding complexity can be managed by limiting group sizes.

## Abstract

This paper explores multiuser multiple antenna systems as a means to enhance the spectral efficiency of aeronautical communications systems. To this end, the outage regime for a multiuser multiple antenna system is studied within a realistic geometry-based stochastic air-ground (AG) channel model. In this application, users (aircraft) transmit air traffic management data to the ground station at a predefined target rate. Due to the nature of the AG propagation, we argue that the relevant performance metric in this context is the information outage probability. We consider the outage probability under three decoding approaches. The first is based on successive interference cancellation (SIC). The second extends the first approach by considering joint group decoding. The third is a version of the second that limits the size of the jointly decoded user groups in order to lower the decoding complexity. The results show that joint group decoding, even in groups of only two, can significantly increase the spectral efficiency in the AG channel by allowing a large number of aircraft to transmit over a non-orthogonal channel with very low outage probabilities.