Impact of Node Speed on Throughput of Energy-Constrained Mobile Networks with Wireless Power Transfer

A wireless charging station (WCS) transfers energy wirelessly to mobile nodes within its charging region. This paper investigates the impact of node speed on the throughput of WCS overlaid mobile networks when packet transmissions are constrained by the energy status of each node. The energy provision for each node depends on its moving speed. A slow-moving node outside the charging region is unable to receive energy from WCSs for a long time, while one inside the charging region consistently recharges the battery. Reflecting on these phenomena, we design a two-dimensional Markov chain, where the states respectively represent the remaining energy and the distance to the nearest WCS. Solving this enables the following theoretic insights. Firstly, the throughput is a non-decreasing function of node speed. With faster node speed, the throughput converges to that of the independent and identically distributed (i.i.d.) mobility model where nodes can move anywhere without being restricted by their previous positions. Secondly, if the battery capacity of each node is infinite, the throughput is equivalent to that of the i.i.d. mobility model regardless of node speed. Finally, the throughput scaling is calculated as Θ ( min ( 1, mn ) c( m n ) ) , where n and m represent the number of nodes and WCSs, respectively.