Array Splitting and Radar Beamforming for Uplink ISAC Mode With Massive MIMO

Integrated sensing and communication (ISAC) is a key enabler for sixth generation (6G) networks, allowing spectrum and infrastructure to be shared for both communication and sensing. While downlink ISAC has been widely explored, uplink ISAC provides unique benefits, including preserved downlink throughput, flexible probing, and advanced base station processing. This paper studies uplink ISAC with massive multiple-input multiple-output, exploiting its spatial resolution and multi-user support. We formulate a joint optimization for array splitting between the receive and transmit arrays and radar beamforming, and propose a low-complexity solution to this mixed-integer problem. Simulations show the method effectively balances communication and sensing.