Waveform Design for Integrated Data and Energy Transfer

Radio frequency (RF) signals can be relied upon for conventional wireless data transfer (WDT) and for challenging wireless energy transfer (WET), which triggers the significant research interest in the topic of integrated data and energy transfer (IDET). However, none of the existing works considers high-efficient waveform design for IDET. In an IDET system, a hybrid access point (H-AP) superimposes the modulated symbols destined to multiple WDT users by exploiting the power-domain non-orthogonal multiple access (NOMA), while WET users are capable of harvesting the energy carried by the superposition symbols. In order to maximize the amount of energy transferred to the WPT users, we propose a joint design of the energy interleaver and the constellation rotation based modulator in the symbol-block level by constructively superimposing the symbols destined to the WDT users in the power-domain. Furthermore, a transmit power allocation scheme is proposed to guarantee the symbol-error ratio (SER) of all the WIT users. By considering the sensitivity of practical energy harvesters, the simulation results demonstrate that our scheme is capable of substantially increasing the WPT performance without any remarkable degradation of the WIT performance. Moreover, we propose a multi-carrier IDET transceiver relying on superposition waveforms consisting of multi-sinusoidal signals WET and OFDM signals for WDT. The outdated channel state information (CSI) in aging channels is employed by the transmitter to shape IDET waveforms. With the constraints of transmission power and WDT requirement, the amplitudes and phases of the IDET waveform at the transmitter and the power splitter at the receiver are jointly optimized for maximizing the average direct current (DC) among a limited number of transmission frames with the existence of carrier frequency offset (CFO). For the amplitude optimization, the original non-convex problem can be transformed into a reversed geometric programming problem, and then it can be effectively solved with existing tools. As for the phase optimization, the artificial bee colony (ABC) algorithm is invoked in order to deal with the non-convexity. Iteration between the amplitude optimization and phase optimization yields our joint design. Numerical results demonstrate the advantage of our joint design for the IDET waveform shaping with the existence of the CFO and the outdated CSI.