Investigation Of Location Algorithm Of Nlos Error Mitigation In Cellular Networks

Wireless location has been widely applied to military and civil technologies. With the steep development of CDMA technology in the past ten years, cellular mobile communications have expanded rapidly. The services that all are based on Mobile Station (MS) in the network, such as public safety, emergency management, location sensitive billing, system design, fleet management and intelligent transportations systems, network layout and design, network QoS, radio resource management, and so on, have much to do with wireless location. In order to improve the location accuracy of the MS in the network, the main factors resulting in measurement errors must be studied and resolved, besides the algorithms with high solution. Because of the practical channel condition, no-line-of-sight always exists between the MS and Base Station (BS), which have become a key technology and hotspot in the research about Wireless Location.The no-line-of-sight problem is studied in the paper. At first we deeply discuss and analyze no-line-of-sight error, the determinative factor resulting in serious location accuracy. Based on the analysis of the characters of the no-line-of-sight propagation, some practical geometrical or statistical models used to simulate those no-line-of-sight error mitigation algorithms are established. The emphasis in the paper is how to eliminate or mitigation the effect of the no-line-of-sight problem. Many materials relevant to no-line-of-sight problems are studied and investigated, and those algorithms also are simulated with the no-line-of-sight propagation models above. As a result, a based time of arrival location algorithm is proposed to mitigate the no-line-of-sight propagation effect. Simulation and comparison of performance with other existing methods have shown its effectiveness of no-line-of-sight error mitigation in location estimate.A lot of methods have been proposed in some papers to eliminate or mitigation the effect of the no-line-of-sight problems. But their effectiveness of no-line-of-sight error mitigation in time of arrival or time difference of arrival is...