Co-Designing Statistical MIMO Radar and In-band Full-Duplex Multi-User MIMO Communications

We consider a spectral sharing problem in which a statistical (or widely distributed) multiple-input-multiple-output (MIMO) radar and an in-band full-duplex (IBFD) multi-user MIMO (MU-MIMO) communications system concurrently operate within the same frequency band. Prior works on joint MIMO-radar-MIMO-communications (MRMC) systems largely focus on either colocated MIMO radars, half-duplex MIMO communications, single-user scenarios, omit practical constraints, or MRMC co-existence that employs separate transmit/receive units. In this paper, we present a co-design framework that addresses all of these issues. In particular, we jointly design the statistical MIMO radar codes, uplink (UL)/downlink (DL) precoders of in-band full-duplex multi-user MIMO communications, and corresponding receive filters using our proposed metric of compounded-and-weighted sum mutual information. This formulation includes practical constraints of UL/DL transmit powers, UL/DL quality-of-service, and peak-to-average-power ratio. We solve the resulting highly non-convex problem through a combination of block coordinate descent and alternating projection methods. Extensive numerical experiments show that our methods achieve monotonic convergence in a few iterations, improve radar target detection over conventional codes, and yield a higher achievable data rate than standard precoders.