Research Of The Data Gathering Protocols For Wireless Sensor Networks

Along with the development of micro-sensor technology, RFID technology and the wireless communication technology, information industry has entered the 3rd wave represented by "Internet of Things" and the wireless sensor networks. The human society is about to enter into a new era of communication people to people, people to objects, objects to objects. The imagination of"Experience China","Smart Earth"will come true. As the van of the third wave, wireless sensor networks will be widely used in national security, military defense, industrial control, transportation, medical etc.It is an extreme challenge to seek for a highly efficient data gathering protocol, for the wireless sensor networks are characterized by limited power, high node density, topology-dynamic and application related. "Energy Hole" and "Funnel Effect" are the problems which must be solved in the first place for data gathering sensor networks. Most of the current data gathering protocols are based on network structure, or mobility, or quality of service. Few of them are fit for large-scale nodes networks and give attention to the lifetime of network and real-time.This paper mainly focuses on applications of wireless sensor networks which require the high quality of service with real-time and conducted thorough studies on the data gathering protocols which meet this demand. The main work and contributions are as follows:Firstly, after analyzing the total energy consumption and load distribution of the static base model and randomly walking base model, this paper designs a data diffluent model and analyes its boundary which minimizes the total network energy consumption and minimizes the max value of node load. At last, a span value of the diffluent boundary which can prolong the network lifetime is given out.Secondly, a data diffluent gathering protocol with multiply mobile base stations is put forward based on the diffluent strategy model. The diffluent boundary L divides the round area into two parts, one gathers the datas with many-to-one method, while the other with many-to-many method. The nodes with the distance from round center less than L send the datas to the round center base station along the shortest path, while the others with the distance more than L send the datas to the outer data buffers along the shortest path. The mobile bases move periodically along the outer round with the same speed and direction. This protocol substantially cuts down the propagation delay comparing with the single mobile base station and fits for networks with high density nodes and widespread data gathering. Simulation results show that this protocol can deplete energy in the round coverage relatively equally and balance the overload so as to prolong the network lifetime.Thirdly, to further reduce the packet processing delay, this paper proposes two kinds of optional modes. One is the green channel mode to reduce the transport delay, which adopts the dynamic priority and predicted strategy; The other is that the bases intelligently and collaboratively move with non-uniform speed to cut down the wait delay.