A Receiver-Initiated Big Slot Scheduling MAC Protocol for Reducing Collision in Wireless Sensor Networks

Two basic requirements in designing a MAC protocol for industrial wireless sensor networks (IWSNs) include the timeliness and the reliability of data transmission. For the former, the protocols in general rely on the use of TDMA. For the latter, they have to take into account various interfering factors existent in environment. One approach uses CSMA/CA in data transmission in which a sender acquires a channel using some control messages before sending data and then the receiver replies with an acknowledgement message for the successful reception, while guaranteeing the timeless of data transmission using TDMA. Since the size of control message is relatively big when considering the small size of data in WSNs, it is desirable to reduce the number of control messages. Thus, a receiver-initiated data transmission method is proposed to reduce the number of control messages as well as the number of competing nodes. Since the receiver-initiated approach works well when data transmission can be predicted, it is applied to the BigMAC protocol that uses a level-order transmission in a tree topology. Simulation results indicate that the proposed technique contributes to improving reliability clearly and reducing one round of data gathering time, leading to the reduced energy consumption.