Energy relaying in mobile wireless sensor networks

In wireless sensor networks, limited battery capacity in each sensor node restricts the reliability of the network. This restriction can be somewhat removed by recharging the node batteries through wireless energy transmission. In a mobile wireless sensor network, if there is only one energy station that can transmit energy, the sensor nodes have to rely on their mobility to receive energy from an energy station. When a node battery is depleted, the node stops activating and stays idle until it recharges its battery. As the number of such idle nodes increases, the reliability of the wireless sensor network will decrease. If energy can be relayed via mobile nodes, a battery-depleted node can recharge its battery with higher rate, which affects the reliability of the network. In this paper, we show that if the energy transmission efficiency exceeds a certain threshold then the reliability of the network can always be improved.