No abstract

Joint beamforming for integrated sensing and communication (ISAC) is an efficient way to combine two functionalities in a system at the waveform level. This letter proposes a beamforming design for ISAC systems with finite alphabet signaling. We formulate a problem to maximize the minimum Euclidean distance (MMED) among noise-free received signal vectors under a sensing constraint and a given power constraint. To tackle the formulated optimization problem, we transform it into a semi-definite programming (SDP) and solve it by the semidefinite relaxation (SDR) method. Comprehensive comparisons with existing schemes show that our proposed beamforming offers lower symbol error rate (SER), higher mutual information, and also better sensing performance than existing ISAC beamforming designs.

This paper proposes a non-uniform beam pattern modulation (NUBPM) scheme for integrated sensing and communication (ISAC) systems, where the beam pattern indices are adopted to carry additional information, increasing the spectral efficiency. We analyze the sensing performance and spectral efficiency of the proposed NUBPM scheme, which depend on the beam patterns and their activation probabilities. Furthermore, to improve the performance of the NUBPM-enabled ISAC systems, we investigate the beam pattern set design and activation probability optimization. Simulation results show that the proposed scheme considerably outperforms existing ISAC designs in spectral efficiency while keeping the same sensing performance. The gained spectral efficiency through the proposed scheme can also be traded off for novel equilibria between communication and sensing performance for ISAC systems.

Communication and sensing are two important features of connected and autonomous vehicles (CAVs). In traditional vehicle-mounted devices, communication and sensing modules exist but in an isolated way, resulting in a waste of hardware resources and wireless spectrum. In this paper, to cope with the above inefficiency, we propose a vehicular behavior-aware integrated sensing and communication (VBA-ISAC) beamforming design for the vehicle-mounted transmitter with multiple antennas. In this work, beams are steered based on vehicular behaviors to assist driving and meanwhile provide spectral-efficient uplink data services with the help of a roadside unit (RSU). Specifically, we first predict the area of interest (AoI) to be sensed based on the vehicles' trajectories. Then, we formulate a VBA-ISAC beamforming design problem to sense the AoI while maximizing the spectral efficiency of uplink communications, where a trade-off factor is introduced to balance the communication and sensing performance. A semidefinite relaxation-based beampattern mismatch minimization (SDR-BMM) algorithm is proposed to solve the formulated problem. To reduce the hardware cost and power consumption, we further improve the proposed VBA-ISAC beamforming design by introducing the hybrid analog-digital (HAD) structure. Numerical results verify the effectiveness of VBA-ISAC scheme and show that the proposed beamforming design outperforms the benchmarks in both spectral efficiency and radar beampattern.Index Terms-Integrated sensing and communication (ISAC), vehicular behavior-aware beamforming design, the intelligent transportation system (ITS), and vehicular networks.