MIMO-NOMA Design for Small Packet Transmission in the Internet of Things

TL;DR

This paper introduces a novel MIMO-NOMA scheme tailored for small packet IoT transmissions, effectively serving users with similar channel conditions by creating effective channel gain differences.

Contribution

It proposes a new MIMO-NOMA design that does not rely on users having different channel conditions, addressing a key limitation of existing schemes.

Findings

The scheme meets QoS for one user while opportunistically serving another.

Analytical results show effective channel gain differentiation.

Numerical simulations confirm improved performance in similar channel conditions.

Abstract

A feature of the Internet of Things (IoT) is that some users in the system need to be served quickly for small packet transmission. To address this requirement, a new multiple-input multiple-output non-orthogonal multiple access (MIMO-NOMA) scheme is designed in this paper, where one user is served with its quality of service (QoS) requirement strictly met, and the other user is served opportunistically by using the NOMA concept. The novelty of this new scheme is that it confronts the challenge that most existing MIMO-NOMA schemes rely on the assumption that users' channel conditions are different, a strong assumption which may not be valid in practice. The developed precoding and detection strategies can effectively create a significant difference between the users' effective channel gains, and therefore the potential of NOMA can be realized even if the users' original channel conditions are similar. Analytical and numerical results are provided to demonstrate the performance of the proposed MIMO-NOMA scheme.