Wireless Sensor Network Routing Protocols Research And Improvement

Along with the development of the sensor technology and the microelectronic technology, the Wireless Sensor Networks (WSN) emerges at this historic moment. It is a new domain of information technology, as a collection of gathering, transmission, fusion and analysis of data. It has vast advantages, such as it can be easily expanded, with great reliability and low cost. WSN is greatly implied in military, environment monitoring, emergency, the air defense, home use and transportation, with great prospect and is considered one of the major information technologies of 21st century.We can conduct more thorough research on it unless we deeply grasp WSN's architecture. WSN is actually a wireless network which is constituted by numerous sensor nodes situating arbitrarily on to-be-examined region by the way of self-constitution. Its purpose is to sense, gather and transmit each kind of information which is covered by the network, and then transmit it to the observers immediately. WSN usually includes sensor nodes, the gathering nodes and management nodes. And its core is sensor nodes.The function of The Route Agreement is to seek the optimized way between source nodes and the target nodes and retransmit the data along the optimized way by different groups. The Route Technology is one of the core technologies of WSN. This paper analyses thoroughly the Route Agreement of WSN and puts forward some improvement programs.The Route Agreement of WSN is quite different from the traditional Ad-hoc network. Energy first—its initial purpose of The Route Agreement is to protract the life of network. Only partial routing information can be stored in the nodes and computers resources of WSN. The Route Agreement also takes the data as the center. It does not rely on the only mark-nodes. It can reject the redundant data during the data aggregation. A Route Agreement is only applied to a certain related situation.The Route Agreement of traditional Ad-hoc network can not be directly used in WSN. The new suitable Route Agreement is being developed recently. The existing Route Agreement of WSN can be divided into two types: Plane Route Agreement and Bunch Route Agreement. The author has placed great emphasis on LEACH-the classical Bunch Route Agreement. She has also made some improvement and finally proposed a new effective Route Agreement.The advantages of LEACH are this: nodes forms the bunch, then internal nodes makes a bunch head in turn. The data gathered by the bunch head are transmitted to the base-depot. In this way, much energy is saved in the duration. But some latent questions are discovered. Data are transmitted between the nodes of bunch head and base depot. The bunch head which lies far from the base depot may die early. That may influence the life of the network. Otherwise, once the bunch establishing, nodes broadcast are correspondent with CSMA Agreement. The performance of network may be reduced on a large scale. In order to solve the above-mentioned questions, a new agreement is put forward. First, data are still transmitted directly between the bunch nodes and nodes of bunch head, while some advanced routes are introduced to the bunch and base. Second, CSMA/CA takes the place of CSMA of LEACH. In the new agreement and collision-avoiding mechanism is also adopted. Thus the energy validity of the entire network is obviously enhanced and the life of network is also prolonged.The operating process of the new agreement includes several rounds. The start of each round is initialization stage. When the stage starts, a time is set to maintain the synchronization of the whole network. Each node in the network should determine whether it can be bunch head according to the pit. This algorithm ensured that node in the network becomes the bunch head in turn. After, each node of bunch head transmit data packet which contains the following contents: the ID of the node, the location of the node and the current energy. Then, each node will receive several data packets from different nodes of bunch heads. And finally it chooses a strong bunch to join in.The stable stage begins after the establishment of bunch. In this stage, many time twinkles are contained. Node transmits the gathered data the node of bunch head which first reject the redundant information and then transmit the data the base depot. According to the new agreement, the node of bunch head has to choose the Multi-Route when transmitting the data to the base depot. For example, when A transmit the data packet, it has to calculate the value of D(x), D(x)=dis(A,X)dis(A,X)+dis(X,BS)dis(X,BS) and then calculate the minimum D(B). Only when square sum of A to B and B is smaller than that of A to Base Depot, and the remnant energy of A is less than that of B, B can be the mid-transmitting node. In this way, the energy consumption of nodes, which are far from the base depot, can be reduced, and the validity of energy is improved, thus the life cycle of the net work is prolonged. When B receives the data from A, it determines the route from node B to Base Depot using the same algorithm.After describing the operating process of new agreement, we conduct simulation by using TOSSIM/Tiny OS. This paper attaches great importance on the realization of algorithm and simulation on the basis of brief introduction of Tiny OS system and nes C language. First, in order to simulate some correspondence in network, we can use a document to establish the topology structure of network and compile a program to real the topology and set network noise. The main body of algorithm design consists of two parts: configuration files and modules. In the configuration part the using modules are mainly stated; while the concrete program-realization is included in the module. In Tiny OS, 3 important links are controlled by three timers.Man can use the simulator-TOSSIM of Tiny OS system to simulate the implementation of Route Agreement: First, compile the program under the Cygwin environment, then establish the connection and operate programs with python script, finally draw the conclusion through observing the operating result.The analogue result proves: if the new agreement mentioned in the paper is accepted, the weakening of energy is very balanced when each node transmits information to the base depot. Thus, such phenomena can be avoided as the shortening of network life caused by the premature death of several nodes which lie far from base depot. Compared with traditional LEACH, the new agreement mentioned in the paper has obvious advantages. By using the new agreement, validity of energy can be improved, and the life cycle of the whole network also can be prolonged. It benefits a lot to the research and improvement of the agreement of WSN.