6G System Evolution with Integrated Sensing and Communications

We discuss and summarize the architectural options for radar type sensing in cellular networks to enable integrated sensing and communications (ISAC) operations. The key characteristics of monostatic and multistatic radar operation are briefly reviewed and the design challenges for cellular ISAC are discussed. We focus then more closely to the design problem of downlink transmit beamforming at a base station serving multiple users and performing simultaneously monostatic target sensing. We discuss beamformer design with hybrid beamforming transceiver architecture. We also cover its interplay with frequency domain resource allocation in multicarrier ISAC system. The waveform design principles are introduced for single and multiple targets. The implications of wideband multicarrier operation are described and the performance optimization in this regime is discussed. Both optimization-based algorithms and deep unfolding-based data driven ISAC design are introduced.