Abstract: Location awareness is to determine the coordinates of nodes in a sensor nets which refer to a group of sensors and actors linked by wire or wireless medium to perform distributed sensing and acting tasks. Most previously proposed algorithms to the problem assume that nodes are deployed in planar area. However, these algorithms are unable to locate nodes of three-dimensional nets. A new location awareness algorithm, called Alternating Combination Quadrilateration(ACQ), is presented for three-dimensional deployment. This algorithm determines the location of unknown nodes by employing different weighted function, weighted polyhedron and weighted centroid. The unique characteristics of ACQ are highly accurate and robust to the range measurement error.