Reliable Transport Algorithm Based On Hierarchy For Wireless Sensor Networks

Wireless Sensor Network is a new and self-organized wireless network without complex infrastructure. With the development of microelectronics, sensor technology and telecommunication technology, wireless sensor network has gained so much attention that it has been used in both military and civilian aspects. The nodes have very limited energy, storage space and computing ability. Most of the nodes are randomly deployed in complex environment with highly channel error ratio, and low cost made the nodes failure-prone. Large-scale data transmission task can likely make network congestion under the limited hardware conditions. Based on all the characteristics above, we can say the data transmission reliability faces a lot of restrictions.Referring the characteristics of wireless sensor networks above, this paper's first proposed a algorithm considering the choice of reliable route, congestion avoiding and control and the deal of failure nodes(for short RCNF). It discusses the reliability of data transmission based on the hierarchy structure. It adopts measures in three aspects: For one aspect, it constructs reliable route and a candidate one considering three main effective elements including the node's current residual energy, current buffer usability and channel error ratio; For another, the algorithm do a detection of pre-congestion according to the spare space of a node buffer. If it meets the requests, the algorithm makes a dredge on the route avoiding the probable congestion. At the same time, we erect a monitor on each route to solve congestion problem as soon as possible; the last aspect is about the classified handle of cluster head or common node's losing efficiency problem. It must contain the thinking of topology variation and the failure data transmission of in cluster nodes for the useless of the cluster head. RCNF algorithm orders the nodes to join in a new nearby cluster then keeps collection of the data. At last, compare with the typical MESH algorithm by OMNET++ simulation, we find RCNF has better performance in data transmission in a hypothesis of having a good keep of network life time.Based on the RCNF algorithm, the thesis proposed an algorithm taking account of the route optimization and retransmission mechanism. Considering the WSN's "hot spot" problem, the "key node" issues of finding path and retransmission problem, CHKR algorithm first change the last two hops into random choose for balance the hot spot energy consumption. Meanwhile, this algorithm makes the RCNF's route better and takes account of node energy consumption besides the three factors above. As a result, it avoids the early dead of some nodes. Retransmission method confirms only for "a collection" of data and it saves the communication amounts and the waiting time of sending node. The methods above make good results in reliable transmission through simulation.