Abstract: Locali}ation takes an important role in wireless sensor networks, while distance measuring is usually the precondition of tracking or positioning. Finding a distance-measuring algorithm with low cost, low overhead and high precision is the main intension of this paper. In this paper, derived from the distributing characteristics of node's fine-grain gradient value in wireless sensor networks' minimum hop gradient field, a way based on the fincgrain gradient to estimate the distance between nodes, namely DV-FGI, was presented. Compared with the DV-hop algorithm, the measuring precision of DV-FGI is improved largely at the nearly same cost and overhead, and the resolution ratio of measuring is improved from communication radio range to the distance interval between neighbor nodes. "hhe theoretical analysis and simulation results validate that the method is cauite effective in the wireless sensor networks deployed with dense nodes.

Key words: Wireless sensor networks, Minimum hop gradient field, Fine-grain gradient, Distance estimating, Degree of accuracy