Cooperative Localization Technologies In Wireless Networks

Localization technologies in wireless networks are of significant impor-tance because location information has lots of applications(e.g.emergency services,search and rescue operations,traffic control,security tracking,etc).In this paper,the cooperative localization technologies are studied in order to further improve the accuracy and reduce the computational complexity of co-operative localization technologies in wireless networks.Firstly,considering the characteristics of cooperative localization,NBP is utilized to localize the target nodes in the wireless networks.Then,novel schemes are proposed in or-der to improve the accuracy and reduce the computational complexity of NBP based cooperative localization in wireless ad hoc networks.As compared with the conventional approaches,the proposed methods significantly reduces the complexity,while the accuracy is still guaranteed in dense wireless networks.The main innovative points and contributions of the paper are listed as follows.1)Nonparametric belief propagation(NBP)algorithm can result in ap-proximately optimal performance for probabilistic localization in wireless sen-sor networks without loops theoretically.However,in loopy networks the ac-curacy of NBP is doubtful and the computational complexity is high.In this paper,a novel approach running NBP on a minimum spanning tree(MST)is proposed,which mitigates the influence of loops and significantly reduces the computational cost as compared with the conventional NBP schemes.In ad-dition,different from other spanning trees,the MST can confine more NBP particles into the bounding circle.Therefore,it shows better resistance to mea-surement errors.2)NBP has practical limitations in dense networks due to the high com-putational complexity and network traffic resulting from the ranging and infor-mation exchanges with neighboring nodes in cooperative localization.In this paper,we design a distributed network formation approach to select a sufficient number of beneficial links resulting in a new network for cooperative localiza-tion,which improves the efficiency of localization owing to the reduction of redundant links.In addition,we develop a metric to judge and filter the invalid NBP particles,which can increase the accuracy of the localization.3)NBP has practical limitations in dense networks due to the high compu-tational complexity and network traffic resulting from the ranging and informa-tion exchanges with neighboring nodes in cooperative localization.We design a dynamic network scheduling method to gradually generate networks for co-operative localization,which improves the efficiency of localization owing to the reduction of redundant links.