Exploiting Zero Forcing and Block Diagonalization Precoding for Multi-User MIMO ISAC: Bridging Communications and Sensing

Abstract

This paper explores the potential of applying Zero Forcing (ZF) and Block Diagonalization (BD), two linear precoding techniques commonly utilized in communications, to a Multi-User Multiple Input Multiple Output (MU-MIMO) Integrated Sensing and Communications (ISAC) setup. The parallels between communications and sensing are highlighted to show the feasibility of extending ZF and BD to ISAC. To enable the implementation of these techniques, the concept of sensing channel is exploited, enabling the treatment of the sensing receiver as an additional user. Furthermore, two user selection strategies extend existing communication-only algorithms to accommodate sensing requirements. The efficacy of the proposed techniques is substantiated through comprehensive simulations. With the proposed solution, a high beampattern gain is maintained for the sensing while keeping good communication performance, only limited by the power allocation between the two functionalities.