Optimization of IRS-Aided Sub-THz Communications Under Practical Design Constraints

We consider the optimization of a smart radio environment where meta-surfaces are employed to improve the performance of multiuser wireless networks working at sub-THz frequencies. Motivated by the extreme sparsity of the THz channel we propose to model each meta-surface as an electronically steerable reflector, by using only two parameters, regardless of its size. This assumption, although suboptimal in a general multiuser setup, allows for a significant complexity reduction when optimizing the environment and, despite its simplicity, is able to provide high communication rates. We derive a set of asymptotic results providing insight on the system behavior when both the number of antennas at the transmitter and the meta-surfaces area grow large. For the optimization we propose an algorithm based on the Newton-Raphson method and a simpler, yet effective, heuristic approach based on a map associating meta-surfaces and users. Through numerical results we provide insights on the system behavior and we assess the performance limits of the network in terms of supported users and spatial density of the meta-surfaces.

Automated summary

This paper investigates the optimization of multiuser wireless networks in a smart radio environment using meta-surfaces at sub-THz frequencies. By modeling each meta-surface as an electronically steerable reflector with only two parameters, the complexity can be reduced and high communication rates can be achieved. The paper provides insights on system behavior through asymptotic analysis and numerical results.