Power Allocation for Joint Communication and Sensing in Cell-Free Massive MIMO

TL;DR

This paper proposes a power allocation algorithm for joint communication and sensing in cell-free massive MIMO systems, enhancing target detection probability while maintaining communication quality, demonstrated through numerical simulations.

Contribution

It introduces a novel power allocation method that balances sensing and communication needs in a centralized cell-free massive MIMO setup, improving detection performance.

Findings

Detection probability increases significantly with the proposed algorithm.

The method improves sensing performance using existing communication symbols.

The algorithm maintains minimal SNR for UEs while enhancing sensing SNR.

Abstract

This paper studies a joint communication and sensing (JCAS) system with downlink communication and multi-static sensing for single-target detection in a cloud radio access network architecture. A centralized operation of cell-free massive MIMO is considered for communication and sensing purposes. The JCAS transmit access points (APs) jointly serve the user equipments (UEs) and optionally steer a beam towards the target. A maximum a posteriori ratio test detector is derived to detect the target using signals received at distributed APs. We propose a power allocation algorithm to maximize the sensing signal-to-noise ratio under the condition that a minimal signal-to-interference-plus-noise ratio value for each UE is guaranteed. Numerical results show that, compared to the fully communication-centric power allocation, the detection probability under a certain false alarm probability can be increased significantly by the proposed algorithm for both JCAS setups: i) using additional sensing symbols or ii) using only existing communication symbols.