Beam Codebook Design for Full-Duplex Integrated Sensing and Communication Systems at Mmwave

This paper investigates a full-duplex (FD) multiple-input multiple-output (MIMO) setting for integrated sensing and communication (ISAC), which enables simultaneous monostatic sensing and communication with a single base station (BS). We consider frequency bands that exhibit sparse propagation characteristics, such as mmWave bands. A key challenge for these systems is the design of hybrid precoders and combiners that facilitate ISAC functionalities while mitigating self-interference (SI) that is caused by concurrent transmission and reception. While prior work has focused on hybrid precoder and combiner design for FD ISAC with prior communication channel and target parameter knowledge, the problem of joint channel and target parameter estimation remains unexplored. We address this gap by designing SI-aware hybrid training precoders and combiners that form a beam codebook optimized for sparse channel estimation. Our design minimizes the mutual coherence, a key metric in compressed sensing, while effectively suppressing the SI to enable accurate joint estimation. We evaluate our approach in terms of estimation accuracy, as well as SI mitigation performance.