Research On Medium Access Control (MAC) Protocols In Wireless Sensor Networks

Wireless Sensor Networks is a new information acquisition, processing and transmissiontechnology. Due to nodes of wireless sensor networks has limited hardware resources, limitedenergy power characteristics. Designing energy efficient communication protocols forwireless sensor network research is very important. Media access control protocol is the mostprominent communication protocol among all protocols. This thesis focus on Medium accesscontrol protocol research area.Media Access Control protocol is fundamental supporting technology for wireless sensornetworks. This protocol coordinates node competition; allocates shared wireless channelresources for nodes, MAC also used to create entire network infrastructure. The protocoldirectly affects wireless channel usage efficiency and network performance. This thesisfocuses on wireless sensor network MAC protocol optimization and analysis the essentialreason that can affect MAC protocol performance. This thesis also gives correspondingsolution on existence parallel transmission, the channel inadequate usage problem caused byexposure terminal and MAC protocol application crossing layer problem.Firstly, aiming at the exposed terminal problems in multi-hop wireless sensor networks, thisthesis proposes the efficient concurrent transmission LACT-MAC protocol based ongeographical location information. The protocol breaks through the limit of concurrenttransmission based on traditional CSMA MAC protocols, for this protocol exploits nodes’geographical location information to achieve the concurrent transmission of exposed terminal,so as to enhance the reuse efficiency of the valuable wireless channel resources. According tothe location coordinates of the nodes, this thesis explores the feasibility analysis of concurrenttransmission of exposed terminal node, and completes the concurrency check. Simulationresults show that, compared to S-MAC protocol, LACT-MAC protocol can significantlyimprove the average throughput of the network, reducing data transmission delay, andeffectively improving the efficiency and performance in wireless sensor networks.Secondly, the thesis focus on the limited energy characteristics of wireless sensor networks,we apply game theory to solve the power control problem to reduce energy consumption inwireless sensor networks. A distributed power control algorithm based on non-cooperativegame theory under incomplete information is proposed, which adopts Signal to Noise Ratio(SNR) as utility function. The purpose of power control algorithm for non-cooperative gameis to achieve the largest utility by optimal power control strategy, thus improve the total network energy efficiency. Moreover, Bayesian Nash equilibrium theorem is introduced tostudy the existence and uniqueness proof of Nash equilibrium algorithm. Simulation resultsshow the effectiveness of the proposed power control algorithm.Thirdly, considering that traditional competitive or scheduling MAC protocols are notsuitable for wireless sensor networks with high-load and intensive nodes due to theoccurrence of low throughput and accumulated delay, this thesis proposes an efficientconcurrent transmission MAC protocol for power control in wireless sensor networks basedon the non-cooperative game theory that works in one channel mode. The protocol uses thenon-cooperative game theory and an incomplete information power control algorithm toachieve multiple link concurrent transmission at the same channel. The simulation resultsshow that the proposed protocol can perform well in the interference environment forconcurrent data transmission significantly; it can improve the network throughput, reduce thedata propagation delay, and save energy. Also, because of the effective of the channelresources, the spatial reusing efficiency can be improved significantly.Lastly, this thesis presents a protocol based on cross-layer optimized protocol (ECL-MACProtocol).this protocol combined cross-layer ideas, information exchange between the barrierlayers in order to achieve optimal network performance., the protocol use the informationfrom routing layer and MAC layer to do joint optimization. Protocol let the routing layerobtain path information. Keep the node active form source node to sink node, the neighbornodes that does not participate in communication are going to sleep to save node energyconsumption. The results show that network with different number of nodes density,ECL-MAC protocol has better lower energy consumption and data transmission thanMAC-CROSS protocol and T-MAC protocol.This thesis focus on the wireless sensor network MAC protocol, which relates to powercontrol, parallel transmission, exposed terminal and cross-layer optimization design, theseresearches provides a good theoretical basis and ideas for future research work.