Non-Overlapped Subarrays Based Wideband Delay-Phase Hybrid Beamforming

Najjar, Akram; El-Absi, Mohammed; Kaiser, Thomas

doi:10.1109/iwmts54901.2022.9832450

Cited by 4 publications

(2 citation statements)

References 14 publications

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“…To overcome the beam split effect, existing works mainly consider the single-layer TTD scheme. However, it requires each time delay line to provide a large-range delay, especially for a large antenna array, and TTD with large-range delay usually has high power consumption, insertion loss, and hardware complexity, which is impractical for TTD circuits [32]. Therefore, to mitigate the beam split effect with low power consumption and hardware cost, we propose a double-layer TTD scheme at the BS.…”

Section: Double-layer Ttd Scheme and Performance Analysismentioning

confidence: 99%

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Beamforming Design for the Distributed RISs-Aided THz Communications With Double-Layer True Time Delays

Sun,

Yan,

Hao

et al. 2024

IEEE Trans. Veh. Technol.

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In this paper, we investigate the reconfigurable intelligent surface (RIS)-aided terahertz (THz) communication system with the sparse radio frequency chains antenna structure at the base station (BS). To overcome the beam split of the BS, different from the conventional single-layer true-time-delay (TTD) scheme, we propose a double-layer TTD scheme that can effectively reduce the number of large-range delay devices, which involve additional insertion loss and amplification circuitry. Next, we analyze the system performance under the proposed double-layer TTD scheme. To relieve the beam split of the RIS, we consider multiple distributed RISs to replace an ultra-large size RIS. Based on this, we formulate an achievable rate maximization problem for the distributed RISs-aided THz communications via jointly optimizing the hybrid analog/digital beamforming, time delays of the double-layer TTD network and reflection coefficients of RISs. Considering the practical hardware limitation, the finite-resolution phase shift, time delay and reflection phase are constrained. To solve the formulated problem, we first design an analog beamforming scheme including optimizing phase shift and time delay based on the RISs' locations. Then, an alternatively optimization algorithm is proposed to obtain the digital beamforming and reflection coefficients based on the minimum mean square error and coordinate update techniques. Finally, simulation results show the effectiveness of the proposed scheme.

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Section: Double-layer Ttd Scheme and Performance Analysismentioning

confidence: 99%

“…We assume N = 128, f c = 300 GHz, θ 0 = π/4, U = 32, K H = 8, K L = 4, and then have P s ≥ 6, P H ≥ 6, P L ≥ 3 according to (32) and (33). To minimize the hardware cost, we set P s = 6, P H = 6 and P L = 3.…”

Section: Normalized Array Gainmentioning

confidence: 99%