WiLO-OFDM Transmission Scheme for Simultaneous Wireless Information and Power Transfer

Lowering the dependency of receivers and sensors on energy supplies is a requirement for a realistic Internet of Things. This is certainly achieved when sensor nodes are powered wirelessly. Local oscillators (LOs), required to receive and transmit modern radio frequency (RF) waveforms, consume a considerable amount of the power budget. We propose a Wireless Local Oscillator (WiLO) concept to move the LO from the sensor to an external location and transmit it wirelessly to the sensor. This WiLO is modeled as a constant tone transmission. As is well known, the sensor can backscatter the constant tone, which enables uplink transmission. Our system approach allows the downconversion of any RF waveform without LO and mixer while simultaneously utilizing the same signal for power transfer. In this work, we demonstrate our approach to different types of OFDM signals, which can be considered as a general complex RF signal example to be received. Our WiLO-based technique to receive any modern communication signal without LO, in combination with harvesting energy from the tone and backscattering on that tone, results in a promising energy-efficient IoT solution. We present the performance model with design requirements for WiLO tone and amplitudes of OFDM tones for feasible reception of WiLO-OFDM. Simultaneous Wireless Information and Power Transfer (SWIPT) applications typically operate in a high SNR regime, and both energy harvesting and information transfer are equally important. The cost of 12 dB performance with an AWGN noisy channel can be acceptable by saving a significant amount of power by removing the LO.