Optimization of time-switching energy harvesting receivers over multiple transmission blocks

Compared with energy-harvesting transmitters, the performance of energy-harvesting receivers has not been fully investigated. The main consumption of energy at transmitters is for transmission, while that at receivers is for information decoding. Hence, the analysis and optimization of energy-harvesting transmitters and receivers are inherently different. This paper considers optimization of a communication system using an energy-harvesting receiver. We assume that the receiver antenna operates over a relatively wide range of frequencies; hence the receiver can harvest energy from both the in-band signal sent by the transmitter and other possibly out-of-band sources. The receiver adopts a time-switching architecture, i.e., in each block, the receiver first harvests energy then decodes information. We assume the energy consumption for decoding is a non-decreasing convex function of the normalized code rate and dominates the energy used for other processing tasks. In this context, we formulate a non-convex optimization problem to maximize the amount of information decoded over multiple blocks. We solve this non-convex problem by converting it into an equivalent convex problem. We also provide numerical examples to validate the accuracy of our analysis and compare our scheme with two suboptimal schemes requiring less overhead.