Synchronous receiver initiated MAC protocol for long-lived sensor networks

SRI-MAC is designed on the basis of synchronized duty cycled MAC protocols. The nodes in SRI-MAC synchronize each other to avoid data packet collisions. SRI-MAC uses receiver-initiated data transmission in order to efficiently and effectively operate over a wide range of traffic loads. It employs an adaptive beacon and a series of RTS/CTS (Request To Send/Clear To Send) packets to reduce duty cycle and minimize idle listening. In SRI-MAC, the senders remain active and wait silently until the receiver explicitly signifies when to start data transmission by sending CTS packet. If the node is not the intended sender, it returns to sleep immediately and continues its sleep as if the medium had been idle. Analytical and Simulation results show that SRI-MAC reduces the energy consumption and achieves an obvious improvement on the network lifetime.