Abstract: In WSAN,actors make decisions and execute appropriate actions according to the data gathered from sensors.So accurate positioning of sensors that perceive the events is very important to implementing exact control policy.Different from those range-free algrithoms in WSN,a mobile location algrithom based on square area was proposed in WSAN．It used mobile actors instead of anchors to locate sensors.First,the area of the unknown node was determined through the movement of actors,secondly,this area decreased through iteration,when precision was satisfied,the centroid of this area was calculated and treated as coordinate of the unknown node.Via simulation experiments,the algrithom is proven to have a good locating accuracy when RSSI error and GPS error exist,and localizing unknown nodes with a few actors can not only save the cost of network deployment,but also can overcome shortcomings of range-free location algrithoms in WSN,which seriously depend on density of anchors.

Key words: WSAN,WSN,Mobile actor,Range-free position,Region division