Fusion center controlled carrier sense multiple access for physical wireless parameter conversion sensor networks

In this paper, a novel fusion center controlled media access control (MAC) protocol for physical wireless parameter conversion sensor networks (PHY-C SN) is proposed. In PHY-C SN, the sensing information is converted to correspond subcarrier numbers of orthogonal frequency division multiplexing (OFDM) signals and sensor nodes can send sensing information simultaneously. Conventionally, each sensor node performs carrier sense for detecting surrounding wireless signal. However, in order to avoid the complexity of a sensor device and to achieve simultaneous transmission from multiple sensor nodes, only the fusion center performs the carrier sense in the proposed protocol. In the proposed protocol, the fusion center detects the surrounding wireless environment and requests sensing information transmission to sensor nodes if no other wireless systems are detected. The transmission power of each sensor is designed not to give harmful interference toward surrounding wireless systems even if each sensor does not have carrier sense function. Finally each sensor node receiving the requested signal simultaneously sends sensing information to a fusion center at the same time. The effectiveness of the proposed protocol is evaluated by computer simulation and confirm the reliable and highly efficient sensing information collection performance.