Interference Networks with Random User Activity and Heterogeneous Delay Constraints

TL;DR

This paper develops coding schemes and theoretical bounds for interference networks with random user activity and mixed delay traffic, addressing IoT system challenges by analyzing the impact of cooperation and traffic heterogeneity on multiplexing gains.

Contribution

It introduces new information-theoretic bounds and coding strategies for heterogeneous delay traffic in interference networks with random activity and limited cooperation rounds.

Findings

Inner and outer bounds on the multiplexing gain region are close and often coincide.

Delay-sensitive traffic has minimal impact on the sum multiplexing gain when cooperation is available.

Operating at high delay-sensitive multiplexing gains does not reduce delay-tolerant gains, increasing overall network capacity.

Abstract

To answer the call for a new theoretical framework to simultaneously accommodate random user activity and heterogeneous delay traffic in Internet of Things (IoT) systems, in this paper we propose coding schemes and information-theoretic converse results for the transmission of heterogeneous delay traffic over interference networks with random user activity and random data arrivals. The heterogeneous traffic is composed of delay-tolerant traffic and delay-sensitive traffic where only the former can benefit from transmitter and receiver cooperation since the latter is subject to stringent decoding delays. The total number of cooperation rounds at transmitter and receiver sides is limited to $\D$ rounds. Each transmitter is active with probability $\rho \in [0,1]$. We consider two different models for the arrival of the mixed-delay traffic: in Model~$1$, each active transmitter sends a delay-tolerant message, and with probability $\rho_f \in [0,1]$ also transmits an additional delay-sensitive message; in Model~$2$, each active transmitter sends either a delay-sensitive message with probability $\rho_f$ or a delay-tolerant message with probability $1-\rho_f$. We derive inner and outer bounds on the fundamental per-user multiplexing gain (MG) region of the symmetric Wyner network as well as inner bounds on the fundamental MG region of the hexagonal model. Our inner and outer bounds are generally very close and coincide in special cases. They also show that when both transmitters and receivers can cooperate, then under Model~$1$, transmitting delay-sensitive messages hardly causes any penalty on the sum per-user MG, and under Model~$2$, operating at large delay-sensitive per-user MGs incurs no penalty on the delay-tolerant per-user MG and thus increases the sum per-user MG.