Design and performance of a directional media access control protocol for optical wireless sensor networks

Sensor networks that use line-of-sight (LOS) laser links can provide spatially efficient and physically secure connectivity. These features are advantageous for low-power communication networks over short distances in environments where LOS is available and where radio-frequency connectivity must be avoided because of interference, low data rates, or security problems. In order for optical wireless (OW) directional networks to provide viable short-range connectivity, the networks must provide signal coverage over an acceptable field of view and operate with efficient media access protocols to minimize random access times for the independent transmitting nodes within the network. In this paper, we present the performance of a directional media access control protocol applied to a uniquely designed OW sensor network. The protocol was implemented using vertical cavity surface-emitting lasers and microcontrollers. The results are discussed with respect to efficiency of operation and optimized performance.