Hybrid LISA for Wideband Multiuser Millimeter Wave Communication Systems under Beam Squint

TL;DR

This paper introduces a hybrid LISA algorithm for wideband mmWave systems that jointly optimizes user scheduling and precoder/combiner design, effectively addressing beam squint and hardware constraints to achieve high sum rates.

Contribution

The work presents a novel hybrid LISA algorithm that accounts for beam squint and hardware limitations, improving multiuser mmWave communication performance.

Findings

Achieves near-optimal sum rate with negligible performance loss.

Demonstrates excellent performance with reasonable computational complexity.

Effectively handles beam squint in wideband mmWave systems.

Abstract

This work jointly addresses user scheduling and precoder/combiner design in the downlink of a wideband millimeter wave (mmWave) communications system. We consider Orthogonal Frequency Division Multiplexing (OFDM) modulation to overcome channel frequency selectivity and obtain a number of equivalent narrowband channels. Hence, the main challenge is that the analog preprocessing network is frequency flat and common to all the users at the transmitter side. Moreover, the effect of the signal bandwidth over the Uniform Linear Array (ULA) steering vectors has to be taken into account to design the hybrid precoders and combiners. The proposed algorithmic solution is based on Linear Successive Allocation (LISA), which greedily allocates streams to different users and computes the corresponding precoders and combiners. By taking into account the rank limitations imposed by the hardware at transmission and reception, the performance loss in terms of achievable sum rate for the hybrid approach is negligible. Numerical experiments show that the proposed method exhibits excellent performance with reasonable computational complexity.