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The extremely large-scale array is a key feature of future wireless communication systems, and the reconfigurable intelligent surface (RIS) gradually develops toward extremely large-scale RIS (XL-RIS) to enhance the communication system performance and compensate for severe path loss. This paper focuses on a secure XL-RIS aided simultaneous wireless information and power transfer (SWIPT) system, where the hybrid analog-digital beamforming architecture of the base station (BS) and the near-field cascaded channels of the XL-RIS are considered. To ensure the security of information transmission for information decoding receivers, artificial noise (AN) is introduced into the transmit signals to prevent interception by potential eavesdroppers, i.e., energy harvesting receivers (EHRs). We aim to maximize the sum received power among EHRs via jointly optimizing the hybrid analog-digital precoders at the BS, the reflection-coefficient matrix, and the AN covariance matrix, subject to the transmit power budget constraint, the minimal rate requirement of information decoding receivers (IDRs), the secure transmission constraints of EHRs, and the unit-modulus phase shifts constraints. Since this optimization problem is non-convex and the variables are tightly coupled, a penalty-based block coordination descent (BCD) algorithm is designed to decouple the original problem into multiple sub-problems and then iteratively solve them by capitalizing on the successive convex approximation (SCA) technique. In particular, the baseband digital beamformers and the analog beamformer are obtained with closed-form expressions using the augmented Lagrangian and BCD methods. Simulation results are presented to demonstrate the effectiveness of the proposed algorithm and it achieves substantial performance gain compared to the other benchmarks. [ABSTRACT FROM AUTHOR]

A highly integrated RF power and information receiving system is proposed in this paper. The system consists of an antenna, a rectifier, and an information receiving module. The information receiving module acts as part of the dc load. To realize high integration, a dual-band, dual-circular-polarized shared- aperture antenna is implemented. The antenna consists of a left-circular-polarized element operating at 2.4-GHz band, and a high-gain, right-circular-polarized $2\times 2$ array operating at 5.8-GHz band. The lower-frequency antenna is for communication, while the higher-frequency one is for power transmission. All the elements share the same aperture, and the radiator of lower- frequency antenna acts as the reflector of higher-frequency elements. Accordingly, a class-F rectifier that matches the higher- frequency array is designed and verified, and a system-level demonstration is implemented. Owing to the high isolation on frequency splitting and polarization diversity, the baseband signal can be successfully demodulated under a 30-dB input-power-level difference at two frequency bands. The base-band information can be displayed by an ink screen. The received RF power can be effectively rectified and power the data-processing modules. [ABSTRACT FROM AUTHOR]

This paper investigates an application of simultaneous wireless information and power transfer (SWIPT) in a cognitive radio (CR) inspired non-orthogonal multiple access (NOMA) framework with an aim to support simultaneous multicast services of delay sensitive traffic to a high priority multicast group and a low priority multicast group, modeled as primary user (PU) and secondary user (SU) respectively. A cooperative NOMA protocol is proposed where the nodes in the SU multicast group (SU-MG), located in between a common base station (BS) and the PU multicast group (PU-MG), act as relays. As an incentive, a provision is made such that the BS could support exclusive downlink transmission to the SU-MG. In view of the challenge of supporting sustainable network operation with their limited battery power, the SU relays are equipped with requisite harvesting hardware to harvest energy from the NOMA signal transmitted by the BS, using the principle of SWIPT. Closed form expressions of outage probabilities of PU-MG and SU-MG and their approximations under high SNR regime are derived to characterize the performance of the proposed protocol. Furthermore, allocation of exclusive time interval to SU-MG and power sharing of NOMA signal are optimized jointly with an aim to minimize the outage probability of SU-MG under the outage constraint of PU-MG. Simulation results are presented to validate the accuracy of the analytical expressions. Results highlight that proposed scheme performs much better in terms of energy efficiency of PU-MG as compared to that of traditional orthogonal multiple access and non-cooperative NOMA, both without SWIPT. [ABSTRACT FROM AUTHOR]

Simultaneous wireless information and power transfer (SWIPT) technology is one of the solutions to the energy shortage problem in Massive multiple-input and multiple-output (MIMO) systems, while the low-resolution analog-to-digital convertor (ADC) is a potential way to significantly reduce the power consumption of radio frequency circuits in Massive MIMO enabled SWIPT systems. In this paper, we focus on the secrecy transmission maximization problem for Massive MIMO-SWIPT systems over Nakagami- m fading channels, where a low-resolution ADC quantization model and a non-linear energy harvester are exploited. By considering proportional fairness, a joint beamforming design and power allocation problem are proposed to achieve the sum logarithmic secrecy rates. To tackle the non-convex maximization problem, the suboptimal solutions of the beamforming design and power allocation are respectively obtained based on a successive convex approximation and a semidefinite relaxation. Numerical results demonstrate the effectiveness of the proposed joint optimization scheme. [ABSTRACT FROM AUTHOR]

Fairness with a α parameter is an important consideration to provide uniform and high quality service for each user when designing a wireless communication system. In general, α -fairness problem includes the proportional fairness and the max-min fairness. In this paper, we consider the problem of α -fairness-based joint power allocation and power splitting for massive multiple-input and multiple-output (MIMO) systems with simultaneous wireless information and power transfer (SWIPT). Different from the existing works, we utilize a low-complexity parametric optimization method to solve the non-convex proportional fairness problem. Furthermore, we develop a joint iterative algorithm to solve the general α -fairness problem and obtain the suboptimal solutions on power allocation and power splitting. Simulation results illustrate the performance of the proposed algorithm. [ABSTRACT FROM AUTHOR]