On the Performance of NOMA-enabled Multi-Sector RIS-aided with ISAC

With the arrival of sixth-generation communication systems, advanced technologies like multi-input single-output (MISO), reconfigurable intelligent surfaces (RIS), and integrated sensing and communication (ISAC) are poised to drive a broad range of Internet of Things (IoT) applications. Integrating ISAC into MISO networks, however, calls for a reassessment of performance metrics such as outage probability and sensing rate. In this work, we propose an innovative multi-sector RIS framework that partitions the surface into independently controlled sectors, each dynamically selecting the closest sector to target users, who are assumed to be distributed following a Poisson point process (PPP). For downlink transmissions, this multi-sector RIS design combines phase-shift control and simultaneous transmission/reflection within the chosen sector. Our approach includes a nearest-sector selection strategy around a reference user, with closed-form approximations for the outage probability derived under the assumption of a blocked direct link between the base station (BS) and users. The framework also enables ISAC by transmitting sensing signals within the selected sector, facilitating both user communication and target detection. Sensing performance is characterized by the sensing rate, with results showing that increasing RIS elements in the multi-sector design significantly enhances sensing capabilities. Overall, the proposed system demonstrates superior performance over traditional STAR-RIS configurations.