| The essential difference between wireless sensor networks and traditional wireless network is the energy limitation for sensor nodes. Therefore, designing an energy efficient sensor system is always a hot point in related research fields. Compared with conventional wireless networks, SENMA has the advantage in energy efficiency and lifespan of the entire network.This paper researches sensor networks with a mobile agent (SENMA) and the media access control (MAC) protocols in this network's structure. The performance of current MAC protocols are compared and a contention opportunity algorithm is proposed according to the characters of SENMA. Contention opportunity algorithm combines both random access and slot allocation. Control packets are sent in the way of random contention while data packets using guaranteed transmission which uses the bandwidth efficiently. With the same or better performance in throughput and end-to-end delay, this algorithm greatly saves node's energy.Network structure is introduced at the beginning, and then the principle and designing procedure of CO are described in detail. A simulation platform is built using OPNET modeler to realize the CO algorithm and to compare the performances with ALOHA and IEEE 802.15.4 mac algorithm. A series of results show a substantial gain for CO in energy efficiency and network throughput. |
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