Advantages of Dual Channel MAC for Wireless Sensor Networks

Traditional low cost radios for wireless sensor networks operate with one frequency channel at any given time. However, recent advances in radio hardware for WSNs made available transceivers that can support two simultaneous channels. In this work, we investigate the benefits of using two parallel independent frequency channels at the MAC layer. In particular, the paper introduces a technique of Dual Channel Multiple Access with Adaptive Preamble (DCMA/AP). The protocol uses two separate frequencies for data and control packets to avoid the use of handshake mechanisms (e.g. RTS/CTS) in order to reduce energy consumption and packet delay. To address the hidden and exposed terminal problems, DCMA/AP enables a receiver to send a busy tone signal on the control channel to notify neighbors that an ongoing reception is in progress. As a result, packet collisions are nullified with an increase of node throughput. Furthermore, an adaptive preamble mechanism in DCMA/AP avoids secondary processes of node synchronization together with a reduction of idle listening of receiving nodes that are considered to be one of the major sources of energy consumption in wireless sensor networks. Finally, DCMA/AP introduces a mechanism of opportunistic crossover speeds up the process of packet forwarding by pre-announcing the successive candidate node intended to receive the packet.