Wireless Sensor Networks, Dv-hop Localization Algorithm And Directed Diffusion Protocol

The self-localization algorithm and routing protocol are two core technologies and the research focus for wireless sensor networks (WSN). Hence, the higher accuracy localization algorithm and energy efficient routing are very significant to the development and application of wireless sensor networks (WSN).In typical self-localization algorithms of WSN, DV-Hop algorithm is superior to range-based localization algorithm in cost and energy consumption, but its localization accuracy is lower. This thesis analyzes and addresses anchors coordinates which were collinear approximately impact on localization and proposes a criterion for testing the validity of anchor tern according to the given error rate of average hops distance and the biggest hops. Moreover, an improved DV-Hop algorithm is proposed for obtaining higher positioning accuracy based on the effective of anchors combination, the weighted average hops distance and the initial value of anchors combination. The simulation results show the improved DV-Hop algorithm can efficiently increase localization accuracy and the judging criterion of collinear approximation is very effectively by comparing with traditional DV-Hop algorithm and the algorithm of weighted average hops distance.There are different levels of energy consumption to nodes after self-positioning, while the energy of each node is limited, which in turn determines the routing protocol must be effectively using energy. Therefore, the thesis proposes an improved routing protocol can adapt these states by rely on self-positioning technology, the character of the directed diffusion routing protocol and wireless transmission of energy model. The algorithm obtained the optimal routing table by controlling the diffusion exploratory messages with optimal hops in the free space according to the limited formula of nodes energy. Moreover, this algorithm adds the process of routing maintenance. The nodes successively use the optimal path and the sub-optimal path. The process of routing maintenance may be start for finding new routing table when the sub-optimal path is fail to transmission. So, it can directed transmit data packet effectively and reduce energy consumption. The simulation results show that the improved routing protocol effectively saves energy and prolongs the networks life.