Optimal Design of RF Energy-Harvesting Network: Throughput and Delay Perspective

We consider a wireless network comprising two types of nodes: Type I node and Type II node. The Type I node has unlimited energy supply and the Type II node is powered by radio frequency (RF) energy harvesting where the RF transmissions by the Type I node are the opportunities for the Type II node to replenish its battery. The Type I node has a data queue for storing data packets generated intermittently and the Type II node has a backlogged data queue. Our objective in this paper is to investigate system throughput and packet delay in an RF energy-harvesting network. Specifically, we find the optimal transmission probabilities of the two nodes which minimize the packet delay of the Type I node while maximizing the system throughput subject to the stability condition of the data queue of the Type I node. The whole system of the two interacting nodes can be exactly modeled by a two-dimensional Markov chain. Instead of following such an approach, we resort to another approximate approach so that our optimization problem can be solved more easily and closed-form solutions are available. The accuracy of the approximate model is validated by extensive simulations.