Integrated Monostatic Sensing and Full-Duplex Multiuser Communication for mmWave Systems

TL;DR

This work tackles the challenge of enabling simultaneous monostatic sensing and full-duplex multiuser mmWave communication using a SI-aware hybrid precoding/combining framework. It introduces SLNR-based designs for both DL communication and sensing at the FD base station, followed by a hybrid factorization to realize the shared analog frontend, while enforcing analog SI constraints. An interference-aware digital processing chain, together with MVDR-based radar processing and OFDM radar for range-velocity estimation, allows separation of MU signals from target reflections and UL transmissions. The approach demonstrates convergence in SI suppression and shows that the system can deliver concurrent DL/UL data and sensing gains with robust performance in representative mmWave scenarios, highlighting its potential for integrative ISAC in next-generation networks.

Abstract

In this paper, we propose a hybrid precoding/combining framework for communication-centric integrated sensing and full-duplex (FD) communication operating at mmWave bands. The designed precoders and combiners enable multiuser (MU) FD communication while simultaneously supporting monostatic sensing in a frequency-selective setting. The joint design of precoders and combiners involves the mitigation of self-interference (SI) caused by simultaneous transmission and reception at the FD base station (BS). Additionally, MU interference needs to be handled by the precoder/combiner design. The resulting optimization problem involves non-convex constraints since hybrid analog/digital architectures utilize networks of phase shifters. To solve the proposed problem, we separate the optimization of each precoder/combiner, and design each one of them while fixing the others. The precoders at the FD BS are designed by reformulating the communication and sensing constraints as signal-to-leakage-plus-noise ratio (SLNR) maximization problems that consider SI and MU interference as leakage. Furthermore, we design the frequency-flat analog combiner such that the residual SI at the FD BS is minimized under communication and sensing gain constraints. Finally, we design an interference-aware digital combining stage that separates MU signals and target reflections. The communication performance and sensing results show that the proposed framework efficiently supports both functionalities simultaneously.

Figures (7)

• Figure 1: Illustration of the integrated monostatic sensing and FD MU communication system operating at mmWave bands.
• Figure 2: Residual SI-to-noise ratio with respect to the iterations of the analog combiner design. The dashed curves show the worst examples.
• Figure 3: Sum spectral efficiency of DL UEs with respect to DL transmit power.
• Figure 4: Sum spectral efficiency of DL UEs with respect to the number of RF chains at the BS. The DL transmit power is set to $P_{\rm DL}=20$dBm.
• Figure 5: Sum spectral efficiency of UL UEs with respect to UL transmit power.