Study On Reliable Transmission Protocol Of WSN-based Mechanical Vibration Monitoring

Wireless Sensor Networks (WSN) is a novel technology for information collectingand processing, which had gotten increasing attention from academia and industry sinceyears earlier. It is innovative and challenging to apply WSN to monitoring ofmechanical vibration. So this paper focuses on reliable transport protocol becausestate-of-the-art protocols hardly support the special requirements of monitoring onmechanical vibration such as high network throughput and precise clock synchronizeddata acquisition. As a result this paper puts forward a MAC protocol that fits formonitoring of mechanical vibration: MPF-MMAC. The proposed MAC protocolsupport synchronized data acquisition and has higher network throughput. Main worksof this paper is listed below.First, this paper puts forwards a novel multi-channel MAC protocol based onTDMA mechanism: MPF-MMAC. MPF-MMAC is designed for monitoring onmechanical vibration; it takes multi-layer cluster network topology, which makesnetwork coordination easily and control overhead less. Cooperated with our super-frameexpanding method, MPF-MMAC has low transmission delay and better ability toexpand cluster. And we designed a flexible and controllable channel access method thatcan increase channel utility, which is helpful for improving network throughput.MPF-MMAC utilizes an explicit ACK message to ensure reliable transmission betweentwo hops. Using OMNet++software we simulated MPF-MMAC protocol and evaluatedits performance, and the outcome is given.Second, based on MPF-MMAC we designed a method to do data acquisition withprecise clock synchronization. This method is based on broadcast message that takingsynchronization information, which makes receiver synchronize with sender node andreserve command and time for upcoming execution. Experiment shows that the simplemethod performs pretty nice that the biggest synchronization error of four nodes is lessthan100microsecond.Thirdly, we designed a congestion avoidable transmission mechanism for massdata transmission that fits for mechanical vibration signal data transmission task. Everynode adjusts its message sending rate to keep average bandwidth occupancy based onamount of nodes in the whole network. As well sensor node can change their bandwidthoccupancy by adjusting its priority. At last, we implement our protocol and related method on our own sensor nodeWSN-G2based on IAR complier and uC/OS-II operating system. Experiment isconducted on a metal frame, and the outcome shows that our protocol can apply togeneral mechanical vibration monitoring system smoothly.