?url_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Adc&rft.title=Scalable+Robust+Beamforming+for+Multi-Layer+Refracting+RIS-Assisted+HAP-SWIPT+Networks&rft.creator=Sun%2C+Y&rft.creator=An%2C+K&rft.creator=Lin%2C+Z&rft.creator=Zhu%2C+Y&rft.creator=Al-Dhahir%2C+N&rft.creator=Wong%2C+KK&rft.description=To+mitigate+the+severe+large-scale+fading+and+the+energy+scarcity+problem+in+long-distance+high-altitude+platform+(HAP)+networks%2C+in+this+paper%2C+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%2C+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%2C+this+paper+formulates+a+worst-case+sum+rate+maximization+problem+under+angular+channel+state+information+(CSI)+imperfection%2C+while+satisfying+the+information+rate+requirements+of+the+earth+stations+(ESs)+and+the+harvested+energy+constraint.+To+handle+the+intractable+non-convex+problem%2C+a+scalable+robust+optimization+framework+utilizing+the+discretization+method%2C+LogSumExp-dual+scheme%2C+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.&rft.subject=Fading+channels%0D%0A%2C%0D%0AWireless+communication%0D%0A%2C%0D%0ATransmitters%0D%0A%2C%0D%0AReceivers%0D%0A%2C%0D%0AReconfigurable+intelligent+surfaces%0D%0A%2C%0D%0AOptimization%0D%0A%2C%0D%0ASimultaneous+wireless+information+and+power+transfer&rft.publisher=IEEE&rft.date=2024-02-26&rft.type=Proceedings+paper&rft.language=eng&rft.source=+++++In%3A++Proceedings+-+IEEE+Global+Communications+Conference%2C+GLOBECOM.++(pp.+pp.+1656-1662).++IEEE+(2024)+++++&rft.format=application%2Fpdf&rft.identifier=https%3A%2F%2Fdiscovery.ucl.ac.uk%2Fid%2Feprint%2F10189914%2F1%2Fa275-sun%2520final.pdf&rft.identifier=https%3A%2F%2Fdiscovery.ucl.ac.uk%2Fid%2Feprint%2F10189914%2F&rft.rights=open