# Non-orthogonal Multiple Access for High-reliable and Low-latency V2X Communications

## TL;DR

This paper introduces a non-orthogonal multiple access scheme for vehicular networks that reduces latency and enhances reliability by combining semi-persistent scheduling with distributed power control, optimized through a novel stable matching algorithm.

## Contribution

It proposes a new non-orthogonal multiple access scheme with a stable matching-based resource allocation method for V2X communications.

## Key findings

- Outperforms traditional orthogonal schemes in latency reduction
- Achieves higher packet reception probability
- Converges quickly to a stable resource allocation

## Abstract

In this paper, we consider a dense vehicular communication network where each vehicle broadcasts its safety information to its neighborhood in each transmission period. Such applications require low latency and high reliability, and thus, we propose a non-orthogonal multiple access scheme to reduce the latency and to improve the packet reception probability. In the proposed scheme, the BS performs the semi-persistent scheduling to optimize the time scheduling and allocate frequency resources in a non-orthogonal manner while the vehicles autonomously perform distributed power control. We formulate the centralized scheduling and resource allocation problem as equivalent to a multi-dimensional stable roommate matching problem, in which the users and time/frequency resources are considered as disjoint sets of players to be matched with each other. We then develop a novel rotation matching algorithm, which converges to a q-exchange stable matching after a limited number of iterations. Simulation results show that the proposed scheme outperforms the traditional orthogonal multiple access scheme in terms of the latency and reliability.