Active IRS-Enabled Integrated Sensing and Communication: Extending Sensing Coverage to Non-Line-of-Sight Areas

This work proposes a system-level multi-beam setup for an integrated sensing and communication (ISAC) system with an active intelligent reflecting surface (IRS). The system includes a multi-antenna base station (BS), active IRS, communication users, and targets in both line-of-sight (LoS) and non-line-of-sight (NLoS) regions. Signal processing is centralized at the BS to reduce costs, given the lack of dedicated sensing receivers in the IRS. While the communication beam consistently targets the user equipment (UE), the system dynamically directs the sensing beam towards areas of interest for environmental monitoring. LoS targets are directly detected using the sensing beam, while the active IRS aids in NLoS target detection by intelligently reflecting the sensing beam, thus creating a virtual LoS link via the BS-IRS-target-IRS-BS path. This innovative approach extends the sensing capabilities of the system to previously inaccessible NLoS areas. Finally, the performance of the system is evaluated by computing the root mean square error (RMSE) of the estimated distance and radial velocity of targets in both LoS and NLoS scenarios, while considering various frequency bands and antenna configurations.