Location discovery in wireless sensor network (WSN) is the process that sensor nodes collaborate to determine the position for unknown sensor nodes. Anchors, sensors that know their locations, are expensive but are required to be deployed into the WSN to solve this problem. Thus it is desirable to minimize the number of anchors for this purpose. In this paper, we propose an anchor deployment scheme and a novel bilateration locationing algorithm to achieve this goal. The basic idea of anchor deployment method is to have three anchors deployed as a group, and locate sensors around them expansively. The novelty of our bilateration algorithm is that it in general requires only two neighbor sensors to determine a node's location. Comparing with the state-of-the-art location discovery approaches, our algorithm gives location estimation with high accuracy, low communication cost and very small anchor percentage. We conduct theoretical analysis about location estimation error and extensive simulation shows that our algorithm can derive sensor location within 4% location error and much less communication cost compared with other algorithms. UMIACS-TR-2003-119