DPC-Inspired Beamforming Design for Integrated Sensing and Communications

Inspired by Dirty Paper Coding (DPC), in this paper we propose a design approach of transmit beamforming for the integrated sensing and communications (ISAC) system that offers simultaneous sensing services via radar and information delivery to users. Specifically, we shape the channel matrix into an equivalent lower triangular matrix. Under this strategy, the communicating users are able to eliminate the multi-user interference (MUI) by using successive interference cancellation (SIC). The corresponding transmit beamforming optimization problem subject to radar constraints is formulated and then solved by a manifold optimization approach. Compared to the conventional design, the idea behind our proposal is to reduce partial burden of beamforming towards interference suppression while taking advantage of low-complexity detection at the receiver to achieve better performances. The simulation results show that our proposed scheme has lower BER than the conventional scheme at low-SNR regime. As for sensing function, the beam pattern of proposed scheme has only a small performance loss compared with the desired beam pattern.