Unsourced Multiple Access with Common Alarm Messages: Network Slicing for Massive and Critical IoT

TL;DR

This paper explores how to efficiently support both massive and critical IoT services using unsourced multiple access, proposing network slicing techniques that enable coexistence with high energy efficiency.

Contribution

It introduces a modified UMA framework for heterogeneous traffic, deriving bounds for alarm and standard messages, and compares orthogonal and nonorthogonal slicing methods.

Findings

Orthogonal network slicing enables coexistence with high energy efficiency.

Nonorthogonal slicing is energy inefficient due to residual interference.

Derived bounds demonstrate the feasibility of supporting both services in Gaussian MAC.

Abstract

We investigate the coexistence of massive and critical Internet of Things (IoT) services in the context of the unsourced multiple access (UMA) framework introduced by Polyanskiy (2017), where all users employ a common codebook and the receiver returns an unordered list of decoded codewords. This setup is suitably modified to introduce heterogeneous traffic. Specifically, to model the massive IoT service, a standard message originates independently from each IoT device as in the standard UMA setup. To model the critical IoT service, we assume the generation of alarm messages that are common for all devices. This setup requires a significant redefinition of the error events, i.e., misdetections and false positives. We further assume that the number of active users in each transmission attempt is random and unknown. We derive a random-coding achievability bound on the misdetection and false positive probabilities of both standard and alarm messages on the Gaussian multiple access channel. Using our bound, we demonstrate that orthogonal network slicing enables massive and critical IoT to coexist under the requirement of high energy efficiency. On the contrary, we show that nonorthogonal network slicing is energy inefficient due to the residual interference from the alarm signal when decoding the standard messages.