A battery recharge model for WSNs using Free-Space Optics (FSO)

One of the most critical limiting factor for a Wireless Sensor Network (WSN) is its battery life. Therefore, a very desirable feature of WSN would be its rechargability to remain operational over longer period of times. However, the nodes needing recharge may not be accessible. In this paper, we present a battery recharge model in WSNs for inaccessible or hard to access environments, at distances up to several hundred meters, using variable power Infrared (IR) laser. While bulk of the sensor network comprises of sensing nodes, the juncture nodes are the ones that relay data towards sink -resulting into faster battery depletion. We present a recharge mechanism for juncture nodes, that utilizes Free Space Optics (FSO) over RF-cliques using IR-laser, Corner Cube Retroreflectors (CCRs) and beam-steering lasers. A Thinfilm Corner Cube Retroreflector (TCCR) is also proposed as a variant to the standard CCR to realize selective recharging. The proposed mechanism provides recharge-ability both for on-demand recharging and scheduled recharging.