The Research Of Wireless Sensor Network Physical Layer And MAC Layer Protocol

The wireless sensor network consists of a large number of sensor nodes which are deployed inthe monitoring area. The sensors in the WSNs form a multi-hop communication network by the wayof self-organizing. The purpose of WSN is to sense, collect and process collaboratively theinformation of the monitored objects within the coverage area, such as humidity, temperature andother data of things. Finally, the data collected will be transferred to the user through the externalnetworks, such as the internet, the mobile communication network, or the satellite communicationnetwork etc. This thesis mainly studies the protocol of physical layer and MAC layer in WSNs.Physical layer is in the bottom of the WSN protocol stack, and it directly faces the transmissionmedium and completes the transmission of data packets. MAC layer is supposed to solve the shareof channel resources and avoid conflict. Physical layer and MAC layer are the key technologies ofwireless sensor networks.This thesis mainly studies the protocols of physical layer and MAC layer in WSNs. Firstly,This thesis analyzes the protocol of physical layer in IEEE802.15.4standard, and studies itsperformance on the three different bands. Secondly, we focus on the typical MAC protocols whichalready exist in the field. The detailed analyses and comparisons of their core idea, theirperformance and their characteristic are investigated. The disadvantages of the existing IEEE802.15.4MAC protocol in its adaptation ability to load change are investigated, and a modifiedalgorithm which is based on the IEEE802.15.4MAC protocol is proposed. The modified protocolhas the ability to adapt to dynamic load. The analytical and simulation results all show that themodified algorithm has better performance, and the algorithm is also in line with the designprinciples for wireless sensor networks. Finally, the summary of the work and the direction forfurther work are presented.