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Localization is an important issue in next generation wireless networks (NGWNs), such as 5G cellular networks, IEEE 802.11ax WiFi networks, and wireless ad hoc sensor network (WASNs). This paper proposes a 3-D localization algorithm for NGWNs by utilizing the concept of radical centers from analytic geometry, and takes WASNs as an example. Assume that an unknown node can measure its distances to four or more anchor nodes (reference nodes). By picking four distance measurements to four anchor nodes, a radical center is computed. Through analytic formulation, the radical center is shown to be able to be treated as an estimation of the unknown node location. Since every four distance measurements generates one radical center (in 3-D space), to further improve and fuse these estimations, effective filtering mechanisms are proposed to filter out the improper estimations. Afterward, the remaining radical centers are averaged, and the solution is the final estimation of the unknown node location. The location errors of the proposed algorithm and the conventional minimum mean square error (MMSE) method were analytically compared. It was shown that the proposed algorithm outperforms the conventional MMSE method both in accuracy and efficiency. Extensive computer simulations were carried out and the results verified the advantage of the proposed location algorithm over the MMSE approach.