The Study On Communication Protocol Based On Sleeping And Selective-Gateway Mechanism

Wireless sensor network is a distributed network system composed of a large amount of micro-sensors, which are distributed in the area to be monitored, and organized by themselves. It is generally used in unattended situations to monitor the environmental parameters or objects of interest, transmit data collected by sensors to remote observers. Then observers can analyze the data to get a view of the environment or objects. Wireless sensor network have a broad application prospect in the fields of scientific research, military, civilian and so on. But sensor nodes' own energy is limited, thus saving energy becomes an important goal in the research of wireless sensor network. There has been a great deal of correlative research. Clustering, sleeping mechanism and multi-hop routing are effective methods for saving energy. But these methods have not been combined together. Moreover, most communication protocols are based on the scheme of distributing sensor nodes uniformly. But this distribution scheme is not helpful for saving energy.Based on the analysis of a large amount of existing communication protocols, this paper proposes sleeping and selective-gateway mechanism based communication protocol (SSGM). Based on the analysis of the node distribution scheme adopted by SSGM, this paper proposes location-based node distribution scheme (LNDS).SSGM adopts the passive clustering strategy to construct network topology, the selection of cluster head takes a mechanism called "first declaration wins", and the gateway is selected according to the rule of the network robust and the equilibrium of energy consumption. Based on the assurance of relative high rate of coverage, some nodes, which accord with conditions, are selected to keep sleeping state. So this protocol can reduce unnecessary consumption of energy and possibility of signal collision. Taking into account of the network robustness and the equilibrium and economization of energy consumption, SSGM can effectively prolong the lifetime of the network. This paper studies the scheme of distributing sensor nodes uniformly, which is adopted by SSGM and most of other protocols, and analyzes energy consumption and density distribution of every area. The result of analysis indicates that the node is closer to the sink, the amount of data need to be transmitted is larger and the energy is consumed faster. If nodes near sink die, the whole network can not work. So how to distribute the nodes is important for the lifetime of the whole network. Based on the analysis, location based node distribution scheme (LNDS) is proposed. Compared with the scheme of distributing sensor nodes uniformly, LNDS can make full use of nodes' energy.