A Low LO Frequency Resonant Beam System for Multiuser Self-Aligning SWIPT

With the explosive growth of the Internet of Things (IoT), simultaneous wireless information and power transfer (SWIPT) has emerged as a core solution for powering low-energy devices. To address the limitations of single-user adaptation and the high cost and power consumption caused by high local oscillator (LO) frequencies of up to 60 GHz, this paper proposes a low LO frequency resonant beam system (LLF-RBS) for multi-user self-aligning SWIPT. Our three-mixer phase conjugation (TMPC) circuit architecture reduces the requirement for key LO frequencies to the 28 and 32 GHz bands, representing an approximate 50% reduction. This architecture enables simultaneous phase conjugation, frequency translation, and information modulation within a low-cost hardware envelope. We theoretically prove that the system’s multi-user beamforming mechanism is physically equivalent to a power iteration algorithm, guaranteeing spontaneous convergence to the channel’s principal eigenmodes without explicit channel state information or digital beamforming control. Simulation results demonstrate that the LLF-RBS achieves adaptive self-alignment and watt-level power transfer for multiple users, attaining a downlink spectral efficiency of up to 21.4 bps/Hz.