Research Of Wireless Location With Cooperative Technology And Signal Of Opportunities

ABSTRACT:With the rapid development of wireless communication and information technology, the commercial scale of localization technology has been increasing. The GPS-based localization technology is often unavailable in the indoor, underground, dense urban areas or under the bad weather conditions, so the land-based ubiquitous wireless signal localization becomes the necessary additional technique. Although it has been commercialized, its performance is limited by the measurement error in the complex environment, which causes low localization accuracy. At the same time, considering the contradiction between the localization accuracy and the complexity, the error mitigation technology with low complexity becomes the research hotspot in the field of localization.Through the review of the related literature and research status, two major research directions are studied in this paper:cooperative localization technology based on wireless network and adaptive localization method based on the signal of opportunity. The research and innovation points are as follows.Regarding to the wireless location technology, this paper introduces the cooperative localization technology. Cooperative localization scheme based on TOA(Time of Arrival) are summarized and analyzed, and it is applied to the2-D cellular network environment. Make use of the cooperation between two mobile nodes mitigate the NLOS (Non-Line-of-Sight) error. The located nodes which meet the conditions upgraded as anchor nodes and then use these nodes and the anchors without NLOS error to estimate the un-located nodes. The simulation results show the effectiveness of the algorithm. We also investigates cooperative localization in cellular networks with hearability problem (hearability problem means the mobile station in a cell of origin can only estimate the distance to its home anchor and nearby MSs, so this node unable to complete the location process.), and put forward a novel multi-ring cooperative localization algorithm, firstly, the traditional TOA location algorithm is used to estimate one mobile node, then estimate the location of the un-located nodes by using the connectivity between these nodes. The simulation results show that the proposed algorithm achieves the comparable performance with the traditional LS (Least-square) algorithm and AHLos algorithm.Regarding to the indoor localization technology, The advantages of fingerprint location algorithm are high location accuracy, no need for additional equipment and general adaptability etc. So fingerprint location algorithm has been widely used. It can be divided into two stages:the off-line stage and the on-line stage. During the off-line stage, we sampling and build the database. During the on-line stage, we compare the RSS with database and calculate the coordinate. At present, most research pay attention on matching algorithm on on-line stage while ignore the load is quite unevenly among wireless access points (APs) caused by user’s uneven distribution. We present an adaptive AP selection strategy based on the signal of opportunity and improving location accuracy. The K-Nearest Neighbor (KNN) and Weighted K-Nearest Neighbor (WKNN) indoor location algorithm are carried out to illustrate the performance of proposed adaptive AP selection strategy. Simulation results show its effectiveness.