全息通感一体化:高能效的波束赋形设计

Holographic Integrated Sensing and Communication: Energy Efficient Beamforming Design

通信感知一体化是解决频谱拥塞问题的重要手段。现有的通感一体化系统依赖高功耗的相控阵,限制了其在功率受限场景中的应用。作为一种低功耗天线,可重构全息超表面可以用于替代相控阵,从而形成全息通感一体化这一新范式。在该范式中,利用可重构全息超表面作为发射天线,可以同时实现高空间自由度与低功耗,进而提升通感一体化系统的整体性能。研究了全息通感一体化系统的能效,通过联合设计基站和全息超表面的波束赋形提升系统能效。然而,由于基站的数字波束赋形和可重构全息超表面的模拟波束赋形相互耦合,使得波束赋形的联合设计具有挑战性。为了应对这一挑战,首先构建了最大化能量效率的优化问题,并提出了全息波束赋形优化算法来解决这一问题。仿真结果显示,与传统基于相控阵的通感一体化系统相比,全息通感一体化系统可以在相同发射功率和天线尺寸的条件下实现更高的能效。

Integrated sensing and communication(ISAC) is a critical technique to solve the spectrum congestion issue. Existing ISAC systems rely on power-consumption phased arrays, which limits their application in power-constrained scenarios. As a lowpower antenna, reconfigurable holographic surfaces(RHSs) can be utilized to replace phased arrays, thus forming a new paradigm of holographic ISAC. In this paradigm, employing RHSs as the transmitting antenna can achieve high spatial freedom and low power consumption at the same time, thus improving the overall performance of the ISAC system. The energy efficiency of the holographic ISAC system is investigated, and the energy efficiency of the system is improved by jointly designing the beamforming of the base station(BS) and RHS. However, the joint design of beamforming is challenging due to the coupling between the digital beamforming at the BS and the analog beamforming at the RHS. To this end, the optimization problem of maximizing energy efficiency is formulated, and the holographic beamforming optimization algorithm is proposed to solve this problem. The simulation results show that compared with the traditional ISAC system based on phased arrays, the holographic ISAC system can achieve higher energy efficiency given the same radiation power and antenna size.