On the IRS Deployment in Smart Factories Considering Blockage Effects: Collocated or Distributed?

TL;DR

This paper analyzes how collocated and distributed IRS deployments affect communication performance in smart factories, considering blockage effects, and provides insights into optimal deployment strategies for different service types.

Contribution

It develops a channel model incorporating blockage effects and derives closed-form expressions for key metrics, comparing collocated and distributed IRS deployments.

Findings

Distributed IRS deployment benefits high blockage density scenarios.

Vertical IRS placement improves received SNR and capacity.

Different deployment strategies optimize eMBB and URLLC services under varying blockage conditions.

Abstract

In this article, we study the collocated and distributed deployment of intelligent reflecting surfaces (IRS) for a fixed total number of IRS elements to support enhanced mobile broadband (eMBB) and ultra-reliable low-latency communication (URLLC) services inside a factory. We build a channel model that incorporates the line-of-sight (LOS) probability and power loss of each transmission path, and propose three metrics, namely, the expected received signal-to-noise ratio (SNR), expected finite-blocklength (FB) capacity, and expected outage probability, where the expectation is taken over the probability distributions of interior blockages and channel fading. The expected received SNR and expected FB capacity for extremely high blockage densities are derived in closed-form as functions of the amount and height of IRSs and the density, size, and penetration loss of blockages, which are verified by Monte Carlo simulations. Results show that deploying IRSs vertically higher leads to higher expected received SNR and expected FB capacity. By analysing the average/minimum/maximum of the three metrics versus the number of IRSs, we find that for high blockage densities, both eMBB and URLLC services benefit from distributed deployment; and for low blockage densities, URLLC services benefit from distributed deployment while eMBB services see limited difference between collocated and distributed deployment.