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Wireless sensor networks(WSN) is a research area of multi-disciplinary, itconsists of a large number of sensor nodes, those nodes with functions of informationcollection, data processing and wireless communication for collaboration awareness,acquisition and processing of monitoring information. WSN has broad applicationprospects. The MAC protocol is one of the key technologies in wireless sensornetworks, MAC protocol determines the way of the sensor nodes access wirelesschannel, and when the exchange of data, so it has become a hot research areas. Energyconstrained is an important factor restricting the development of wireless sensornetworks. If we can improve energy efficiency of the MAC protocol, then the energyefficiency of the entire network will have a positive effect. Therefore, this paper fromthe perspective of energy efficiency, focusing on the energy efficiency of the MACprotocol for wireless sensor networks.S-MAC protocol and TEEM protocol exists some problems of energy waste, inorder to improve these protocols, this paper proposed a low energy consumption MACprotocol (LEC-MAC protocol). First of all, LEC-MAC protocol uses adaptivecontention window adjustment mechanism, which is different from S-MAC protocoland TEEM protocol. LEC-MAC protocol contention window size dynamically adjustsaccording to the network load, if the network load is heavy, LEC-MAC protocol willhave a small contention window, if the network load is light, LEC-MAC protocol willhave a big contention window, this is an effective way to avoid collision caused by thechange of network load, and save energy of nodes. Second, LEC-MAC protocol usesthe extension RTS mechanism, SYNC frame in S-MAC protocol with RTS frameintegration, LEC-MAC protocol reduces the energy wasted by the control overheadrelative to the S-MAC protocol and TEEM protocol, it also reduces the active time andidle listening time of node, these will save node energy too. Finally, LEC-MACprotocol has a very long synchronization cycle, which will reduce the waste of energycaused by frequent synchronization operations in TEEM protocol. The simulation ofLEC-MAC, S-MAC and TEEM on NS2proves that LEC-MAC protocol has lowenergy consumption and high energy efficiency.In LEC-MAC protocol, all nodes use the same transmit power, this will causeenergy waste, so this paper proposed the PCLEC-MAC protocol which is based on power control mechanism. In PCLEC-MAC protocol, the node will select anappropriate power which depending on the communication distance to send messages.This will save energy of node, while the optimum transmit power narrowed the scopeof the traffic of each node, and will reduce the waste of energy due to conflictsbetween nodes. Finally, the simulation of LEC-MAC, PCLEC-MAC on NS2provesthat PC LEC-MAC protocol has low energy consumption and high energy efficiency,while using intelligent wireless meter reading system to verify PCLEC-MAC protocolenergy efficiency in real applications.
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