An Anchor Free Location Algorithm for Large Scale Wireless Sensor Networks

Anchor free location algorithm realizes locating the nodes in the wireless sensor networks only by the wireless transceiver equipped on each node, needs not add any other equipment or hardware. Moreover, anchor free location algorithm, which needs no anchor or only needs to elect some reference nodes during the location process, is very applicable to large scale wireless sensor networks consists of many low-cost nodes. This paper proposes a anchor free location algorithm that is easy to realize and with satisfactory accuracy for many applications of large scale sensor networks. The algorithm proposed in this paper first elects five reference nodes from the homogenous sensors in the network. The reference nodes are chosen according to certain criteria and can be used as "anchors" to form a coordinate system. Other unknown nodes obtain the distances from the reference nodes by hop gradient algorithm, which is triggered by the sink node and executed by the reference nodes one by one. The process of electing the reference nodes and obtaining the distances from the reference nodes are completed simultaneously. Then the coordinate of each node is calculated on itself by newton\´s iteration method. The starting value of iteration is given in this paper to further reduce the computation. This paper also gives the effect of localization by the algorithm in simulation. The location error influenced by node density is analyzed as well. Finally, there is a summary of the entire paper and lay out the future work that worth studying in deep.