Polling Access Control Protocol With Sleep On Wireless Sensor Network Analysis

To the traditional computer and communication network, in physical layer the connected problems of the physical medium to transmit data on are resolved and the data signal to pass correctly in the physical layer are ensured. On top of it is the medium access control layer, how the data frame transmit in medium, the same communication channel is shared, controling medium access is realized in certain way will be resolved in this layer, searching physical address and logical topology (the path in which signal pass by the physical topological) is defined in this layer. Path controling, error finding(not to correct), the sequence of transfered frames and selectable flow controlings also are resolved in this layer. In this thesis, the focus is how controlling medium access in MAC layer is realized. Until now, the mode in which stations access the link of the same channel usually is divided into random competition and polling. Because random competition mode does not need the central controlling site for network control, that network has the advantages of simple structure, flexible foundation, and wide application in distributed network. But when the system load so great heavily that lead to great increaseing competition, resolving and avoiding conflict will become more and more difficult. With this situation happening, the system performance will rapidly decrease. In addition, while the data frame arrive at the station, competition action to channels begin to happen, so at times it will be not suitable for the systems to need little delay and hardly provide reliable QoS. Within above situation, polling has the great advantage of dealing with a heavy load task. In recent years, the research on multiple access technology appear all kinds of correlating ways each other, the multiple access polling to channel has been an important access method applied to the Ad Hoc network and wireless sensor network nowadaysIn this thsis, the classic multiple access polling protocol will be study, the WTRP protocol in this thsis will get improved so that the server gives service to one node, at same time completing query and shift between nodes, as a result the parallel processing of service and query and shift is realized. When the polling system is unloaded, all nodes get into the sleep status in order to save power and extend life of nodes. This kind of improved MAC protocol is suitable for the wireless sensor network. In addition, the probability generating function and embedded Markov chain method is used in this thsis to build the mathematical modeling of this improved protocol and analyse performance to obtain analysis formula on performance parameters.