Age of Information in Flexible Antenna-Assisted URLLC Systems: Performance Analysis and Optimization

Abstract

This paper first delves into investigating the age of information (AoI) performance within flexible antenna-assisted downlink multi-user, multiple-input, single-output (MU-MISO) systems. We focus on scenarios where the base station (BS) integrates a flexible antenna array (FAA) comprising rotatable, bendable, or foldable models. Short packets from multiple users are collectively encoded within the FAA to enhance reliability. A closed-form expression for the average AoI is derived, encapsulating the interplay among finite block length effects, flexible antenna reconfiguration, and power allocation. An optimization problem is introduced to minimize AoI by jointly optimizing power allocation, block length, and antenna angles under reliability and power constraints. The non-convex problem is tackled through an alternating optimization (AO) approach, which involves convex power allocation, block length optimization using Q-function approximations, and antenna angle selection via modified particle swarm optimization (MPSO) without gradient computations. Simulation results demonstrate a substantial 20% reduction in AoI compared to the traditional fixed antenna array.