Study on MAC Protocols Based on Controlling Energy Consumption in WSN

Medium Access Control (MAC) protocol, which plays an important role in using wirelessbandwidth effectively and fairly, defines the rules of access control and medium sharing inwireless sensor networks. Efficient MAC protocol is one of key technologies which enablewireless sensor networks.Several MAC protocols have been proposed. However, they have some drawbacks, suchas boundary node energy consumption, poor node mobility, lack of information sharing amongthe layers. Considering the characters and design requirements of the MAC protocol, in thisthesis, we give a novel scheme, which improves communication fairness among nodes andprolongs the lifetime of the whole network. The main efforts are as follows:Firstly, some basic concepts of WSN are given, after some review of the available typicalMAC protocols and compare the characters and applications of these protocols. Some prospectsfor the research interests in the future MAC protocols are also put forward.Secondly, we consider the issues of the virtual cluster boundary node energy consumption,and provide a time synchronization MAC protocol based on the virtual cluster aggregationalgorithm. This protocol realizes the node election utilizing the remaining energy in nodes. Andthe nodes finish the aggregation of virtual cluster and eliminate boundary nodes via choosingdifferent scheduling table lists according to the maximum weighted information within a cluster.Compared with the original protocol, the new protocol greatly reduces energy consumption andimproves network connectivity.Thirdly, in order to set up a connection with strange nodes in time, an adaptive schedulingMAC protocol is proposed. According to the quantified RSSI figures obtained with predictionmechanism, mobile nodes can dynamically adjust the discovering frequency. By doing so,strange scheduling information can be grasped in advance and achieved quickly the adaptivescheduling. Experiment results show this protocol has a better performance both in static anddynamic network.Finally, considering that the protocol layers in wireless sensor network concern only theirown efficiency factors without information share, we propose a cross-layers MAC protocolbased on min-hop. The protocol solves the problem of forced waking, by means of sharinginformation about min-path and remaining energy from the current node to the sink nodebetween the MAC layer and route layer, and determining the next node with transmitting election strategy. Meanwhile, the nodes only broadcast their own information to those usefulneighboring nodes through setting a competitive index in the searching area. Simulation resultsshow that the scheme prolongs the lifetime of the whole network.