Beamspace Waveform Design and Beam Selection for Lens Antenna Array-Assisted ISAC Systems

In this letter, we investigate the joint beamspace waveform design and beam selection problem for lens antenna array (LAA)-assisted integrated sensing and communication (ISAC) systems. The LAA effectively reduces the number of required radio frequency (RF) chains by transforming the dense spatial domain channel into a sparse beamspace channel. We adopt a more practical power consumption model and aim to minimize the system power consumption while guaranteeing the communication and sensing performance. The system power consumption involves the <inline-formula> <tex-math notation="LaTeX">$\ell _{0}$ </tex-math></inline-formula> norm of the transmitting signal, which makes the objective intractable. To address this issue, we propose an iterative reweighting successive convex approximation (IR-SCA) algorithm, which sequentially relaxes the <inline-formula> <tex-math notation="LaTeX">$\ell _{0}$ </tex-math></inline-formula> norm to a reweighted <inline-formula> <tex-math notation="LaTeX">$\ell _{1}$ </tex-math></inline-formula> norm, and approximates the non-convex quadratic form using its first-order Taylor expansion. Simulation results convincingly demonstrate that the proposed method outperforms fully digital systems in terms of energy efficiency.