To overcome spectrum congestion, a promising approach is to integrate sensing and communication (ISAC) functions in one hardware platform. Recently, metamaterial antennas, whose tunable radiation elements are arranged more densely than those of traditional multiple-input-multiple-output (MIMO) arrays, have been developed to enhance the sensing and communication performance by offering a finer controllability of the antenna beampattern. In this paper, we propose a holographic beamforming scheme, which is enabled by metamaterial antennas with tunable radiated amplitudes, that jointly performs sensing and communication. However, it is challenging to design the beamformer for ISAC functions by taking into account the unique amplitude-controlled structure of holographic beamforming. To address this challenge, we formulate an integrated sensing and communication problem to optimize the beamformer, and design a holographic beamforming optimization algorithm to efficiently solve the formulated problem. A lower bound for the maximum beampattern gain is provided through theoretical analysis, which reveals the potential performance enhancement gain that is obtained by densely deploying several elements in a metamaterial antenna. Simulation results substantiate the theoretical analysis and show that the maximum beamforming gain of a metamaterial antenna that utilizes the proposed holographic beamforming scheme can be increased by at least 50% compared with that of a traditional MIMO array of the same size. In addition, the cost of the proposed scheme is lower than that of a traditional MIMO scheme while providing the same ISAC performance.

中文翻译：

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全息集成传感与通信


为了克服频谱拥塞，一种有前景的方法是将传感和通信 (ISAC) 功能集成在一个硬件平台中。最近，超材料天线被开发出来，其可调谐辐射元件的排列比传统的多输入多输出（MIMO）阵列更密集，通过提供天线波束方向图的更精细的可控性来增强传感和通信性能。在本文中，我们提出了一种全息波束成形方案，该方案由具有可调辐射幅度的超材料天线实现，联合执行传感和通信。然而，考虑到全息波束形成的独特幅度控制结构，设计用于 ISAC 功能的波束形成器具有挑战性。为了应对这一挑战，我们制定了集成传感和通信问题来优化波束形成器，并设计了全息波束形成优化算法来有效解决所制定的问题。通过理论分析给出了最大波束方向图增益的下限，揭示了通过在超材料天线中密集部署多个元件获得的潜在性能增强增益。仿真结果验证了理论分析，表明采用所提出的全息波束成形方案的超材料天线的最大波束成形增益与相同尺寸的传统MIMO阵列相比可提高至少50%。此外，在提供相同ISAC性能的情况下，该方案的成本低于传统MIMO方案。