Abstract According to the coverage characteristics of sensors network in indoor and underground location technology, a scheme of threedimensional (3D) complete coverage was proposed for the location in the narrow space in a tunnel. Besides,the Time Difference of Arrival (TDOA) location technology was employed, meanwhile, the Dilution of Precision (DOP) was selected as the accuracy evaluation index. Thereafter, the changing law of DOP values and positioning accuracy was analyzed while sensors’ spacing increased or decreased. The research shows that positioning accuracy primarily depends on sensor’s radius, width of narrow space, and sensors’ spacing, etc. A simulated insitu test of linear tunnel was carried out, and the result shows that optimization scheme of sensors’ location based on the changing law of DOP can thus dramatically improve the positioning accuracy and reliability.
