Throughput maximization in self-powered wireless MIMO communication system

This paper focuses on the problem of throughput maximization in a self-powered point-to-point Multi-Input Multi-Output (MIMO) wireless communication system, the transmitter of which is powered only by energy harvested from ambient radio signals. The transmitter follows a save-then-transmit protocol in transmission frames. The protocol requires the system first carry out the energy harvesting process which lasts for a fraction of time (referred to as save-ratio), then the rest of time is utilized to transmit data packets. It is assumed that the channel state information and energy harvesting rate are known in advance. The throughput maximization problem in this scenario is formulated, where the save-ratio and power allocation must be optimized simultaneously, and it is converted to an equivalent form which can be easier tackled through the traditional Water-Filling power allocation algorithm. By proving the concavity of the problem, the optimal save-ratio is solved as a function of energy harvesting rate and channel state matrix in closed form. The numerical results show how optimal save-ratio and maximal achievable throughput vary with energy harvesting rate.