I. Introduction
Integrated communication and localization has attracted increasing attention in 5G and beyond [1], [2], [3]. For one thing, massive multiple-input multiple-output (MIMO) and millimeter wave (mmWave) techniques have been demonstrated to significantly improve communication performance in terms of reliability, throughput, and scalability. For another, the deployment of large antenna arrays and the availability of large bandwidth at mmWave improve the angle and delay resolution, thus leading to high accuracy localization [4], [5].