Aining at problem of ranging precision difference caused by different layout height of nodes in WSNs node positioning by RSSI value

on the basis of a lot of experimental data

analyze relationship between RSSI value and distance d while wireless sensor networks（ WSNs） nodes are setup at different height

at the same time

process the measured curves by means of piecewise fitting method and propose a calibration method that utilizes node moving according to constant step length on this foundation to calculate distance d corresponding to RSSI value. Verification result shows that the relative error of node ranging

by means of this calibration method

has been improved greatly. At last

the improved ranging algorithm is applied to WSNs positioning

and simulation results show that the proposed section fitting with mobile calibration method can effectively improve positioning precision.