Abstract:  DV-hop algorithm is a typical range-free localization algorithm in wireless sensor networks, its core idea is to use the hop count multiplied by the average distance per hop to estimate the distance between two nodes. That is to say, hop distance is regarded as the actual distance in the position calculation. The errors accumulation in the process of hop distance calculation is the main factor on influencing the DV-hop algorithm localization accuracy. The paper presents selection strategy of beacon node based on threshold hop count and optimization strategy of average hop distance based on weight. Those strategies reduce error accumulation in the process of hop distance calculation and improve the positioning accuracy. The improved DV-hop algorithm optimizes a scheme for selection of beacon node by threshold hop count. In the scheme, only those beacon nodes whose hop count is less than threshold hop count are used for the position calculation, so error accumulation is reduced from hop count. And for the selection of average hop distance for the unknown node, the algorithm regards optimal hop distance as average hop distance of the nearest beacon node, so error accumulation is reduced from average hop distance. Simulations are performed and the results show that the enhanced DV-hop algorithm greatly improves localization accuracy for different number of beacon nodes, different communication radius and different node density.

Key words:  Wireless Sensor Network(WSN);location algorithm ;hop count, average hop distance