Analysis And Design Of MAC Layer Protocols For Wireless Sensor Networks

Wireless sensor network (WSN) is a self-organizing networks consisting of low-cost, low-power tiny sensor nodes that can wireless communication with each other to perform sensing, data processing and storage cooperatively. In a WSN, sensor nodes are usually supplied by battery. In the most cases, it is hard to change the battery for the nodes. As a result, to save as much energy as possible is one of the major purposes of the research on WSNs.MAC protocol tries to ensure that no two nodes are interfering with each other's transmissions, and deals with the situation when they do. Addition to that, MAC protocols for WSNs should take saving energy into account. Many of the existing proposed MAC protocols could not deal well with the problems of high energy consumption and long delay, thus they do not fit in the need for wireless sensor networks. The characteristics and challenge of MAC protocols for WSNs are described in this paper, and then severe typical MAC protocols for wireless networks are depicted. At last, the defects of these protocols are listed.DRMAC protocol, a new energy-efficient MAC protocol for WSNs is proposed in this paper. DRMAC protocol allows the nodes in the network to sleep when they have no data to transmit, which is similar to S-MAC. However, fixed period of sleeping and listening in S-MAC increase the end-to-end time delay. Besides, it is necessary for nodes to frequently exchange SYNC packets to synchronize with each other. In this case, the throughput of the whole network is decreased while extra power must be consummated to exchange SYNCs. Different from S-MAC, the sleeping period in DRMAC is random, so the nodes do not need to send the extra control frames to synchronize with each other. In this way, nodes can decrease the energy consumption from control overhead and idle listen. Meanwhile, the average delay of data transmission is shortening.The performance of DRMAC is analyzed in theory in this paper, and it turns out that the sensors using DRMAC consumption less energy than those using S-MAC with only half time delay. DRMAC protocol has also been implemented in NS-2 simulator, and the simulating results further prove that the communications in DRMAC cost less power and time.