Collaborative Multistatic Integrated Sensing and Communications-Part III: Autofocus via Image Rendezvous

In integrated sensing and communication (ISAC) networks, the communication capability enables the collaborations for sensing among different ISAC nodes, thus improving the diversity of measurements and thus the performance of sensing. However, the inherent time and frequency synchronization errors prevent a clear image of sensed targets due to the blurriness incurred by the local time/frequency errors. The challenge can be mitigated using autofocus that exploits the target position common to all ISAC nodes for a calibration. In the third part of this paper, the autofocus is accomplished by the methodology of robot rendezvous, where each position estimation is considered as a robot and each ISAC node adjusts its local timing to drive the positions for a rendezvous leading to a joint estimation and time synchronization. The proposed algorithm is demonstrated using numerical simulations.