Simultaneous information and power transfer over broadband channels: Fixed coding rates

Far-field microwave power transfer (MPT) will recharge sensors and other mobile devices wirelessly and avoid operation interruption due to finite battery capacities. Simultaneous wireless information and power transfer (SWIPT) that integrates MPT with wireless communications provides a single solution for dual functions. In this paper, we propose a novel framework for realizing SWIPT in a broadband system. SWIPT is enabled by a proposed reconfigurable mobile architecture that supports both uplink and downlink information transfer (IT). Orthogonal frequency division multiplexing and transmit beamforming are deployed to create a set of parallel sub-channels for SWIPT. Assuming fixed coding rates, transmission power over sub-channels are controlled to maximize the system throughput for different system configurations combining single-user/multiuser systems and downlink/uplink IT. This results in a new class of power-control problems featuring the circuit-power constraints, specifying that the transferred power must be sufficiently large to support the operation of the receiver circuitry. Solving these problems gives a set of power-control algorithms that exploit channel diversity in frequency for simultaneously enhancing the throughput and the MPT efficiency. The optimal algorithms are shown to sequentially allocate mobiles their required power for decoding in ascending order until the budgeted power is spent.