Space Diversity-Based Grant-Free Random Access for Critical and Non-Critical IoT Services

TL;DR

This paper investigates a grant-free IoT access scheme that leverages space diversity through AP relays to improve coexistence and performance of critical and non-critical services over shared wireless channels.

Contribution

It introduces a novel space diversity approach using AP relays in grant-free IoT access, analyzing coexistence strategies for critical and non-critical services.

Findings

AP relays improve throughput and reliability.

Orthogonal resource sharing reduces interference.

Trade-offs exist between service types and resource allocation.

Abstract

In this paper, we study the coexistence of critical and non-critical Internet of Things (IoT) services on a grant-free channel consisting of radio access and backhaul segments. On the radio access segment, IoT devices send packets to access points (APs) over an erasure collision channel using the slotted ALOHA protocol. Then, the APs forward correctly received messages to a base station (BS) over a shared wireless backhaul segment, modeled as an erasure collision channel. The APs hence play the role of uncoordinated relays that provide space diversity and may reduce performance losses caused by collisions. Both non-orthogonal and inter-service orthogonal resource sharing are considered and compared. Throughput and reliability metrics are analyzed, and numerical results are provided to assess the performance trade-offs between critical and non-critical IoT services.