Multi-Node Multi-Band Cooperative Integrated Sensing and Communications: State-of-the-Art, Challenges and Opportunities

Integrated sensing and communication (ISAC), a pivotal advancement in 6G networks, can increase spectrum utilization and support innovative applications such as digital twins and smart cities. Nonetheless, existing single-node ISAC networks face challenges such as restricted coverage, limited sensing capabilities, and the inability to meet the stringent quality of service (QoS) requirements for combined sensing and communication. Multi-node multi-band cooperative ISAC (MNMB-ISAC) networks have emerged as a promising strategy to overcome these challenges. In this study, we introduce a user-demand-driven MNMB-ISAC framework that exploits the advantages of ISAC, multi-node cooperative ISAC, and multi-band cooperative ISAC. This network architecture is designed to provide specialized services for a variety of communications or sensing requirements, substantially improving the network performance through cooperative resource allocation strategies. The empirical performance evaluations confirm the efficacy of the MNMB-ISAC approach in ensuring high QoS, guaranteeing mobility services, and improving edge coverage. Furthermore, we examine the challenges encountered by MNMB-ISAC and prospective research avenues. This work is expected to stimulate further break-throughs in the domain of cooperative ISAC.