MAC-AHEAD: um protocolo cross-layer anycast assíncrono adaptável às condições do canal de comunicação

Abstract

This work presents the MAC-AHEAD, an asynchronous cross-layer anycast protocol for Wire-less Sensor Networks (WSNs). This protocol uses inactive/active duty cycle as a way to reduce power consumption and employs the anycast communication model to reduce the propagation time of data messages. A phased messaging method is responsible for reducing latency in data delivery. In the first phase, a sequence of RTS control messages is sent to discover the next hop on the route and to stagger its wake-up time. In the second phase, the DATA message is sent some hops after the RTS. Thus, RTS and DATA roam the route from source to destination simul-taneously, reducing latency without extra power consumption. To speed up the propagation of RTS, an anycast method is employed. A set of neighbors, called FCS (Forward Candidate Set), are chosen as good forwarders for the data message. The MAC-AHEAD protocol selects as the next router the FCS member that first responds to the RTS. The selection of FCS members is based on two parameters, the proximity of the destination node and the SINR (signal-to-noise/interference-ratio) perceived by the neighboring node when receiving the RTS message. In order to evaluate the performance of MAC-AHEAD, this was compared with the X-MAC and PAX-MAC protocols. The results of the simulations showed, for the scenarios tested, that the proposed protocol surpasses the other two in latency and energy consumption.