%0 Generic
%A Sun, Y
%A An, K
%A Lin, Z
%A Zhu, Y
%A Al-Dhahir, N
%A Wong, KK
%D 2024
%F discovery:10189914
%I IEEE
%K Fading channels  ,  Wireless communication  ,  Transmitters  ,  Receivers  ,  Reconfigurable intelligent surfaces  ,  Optimization  ,  Simultaneous wireless information and power transfer
%P 1656-1662
%T Scalable Robust Beamforming for Multi-Layer Refracting RIS-Assisted HAP-SWIPT Networks
%U https://discovery.ucl.ac.uk/id/eprint/10189914/
%X To mitigate the severe large-scale fading and the energy scarcity problem in long-distance high-altitude platform (HAP) networks, in this paper, we investigate the potentials of a multi-layer refracting reconfigurable intelligent surface (RIS) -assisted receiver for enabling simultaneous wireless information and power transfer (SWIPT) in HAP networks. Unlike the existing RIS-aided reflector and transmitter, the multi-layer RIS-receiver can well overcome the severe 'double fading' effect induced by the extreme long-distance HAP links and fully exploit RIS's degrees-of-freedom (DoFs) for SWIPT design. Building on the proposed RIS-receiver, this paper formulates a worst-case sum rate maximization problem under angular channel state information (CSI) imperfection, while satisfying the information rate requirements of the earth stations (ESs) and the harvested energy constraint. To handle the intractable non-convex problem, a scalable robust optimization framework utilizing the discretization method, LogSumExp-dual scheme, and modified cyclic coordinate descent (M-CCD) is proposed to obtain the semi-closed-form solutions. Numerical simulations demonstrate that the proposed architecture and optimization framework achieve superior performance with lower complexity compared with state-of-the-art schemes in HAP networks.
%Z This version is the author accepted manuscript. For information on re-use, please refer to the publisher’s terms and conditions.