| Now in the background of that various wireless communication technologies develop rapidly and mobile intelligent terminals are widely universal,people’s demands for the location information are increasingly strong.Especially for the indoor place,people increasingly depend on location services to get a variety of useful information.Because very mature outdoor positioning technologies such as GPS can not meet the expected positioning accuracy of people,more and more researchers have been devoted to the research of indoor positioning.Nowadays the worldwide popularity of WLAN technology based on the IEEE802.11 offers more new directions for the development of the indoor positioning.Algorithm Based on RSSI Ringing is one of the most commonly used localization algorithm of WLAN.Ranging technology based on RSSI calculate the distance by constantly diminishing signal strength in the process of transmission.This signal strength,which is widely used in the wireless network location technology,can be easily got and need no special support of hardware.This paper first introduces the origin and the development of the indoor positioning,domestic and foreign research trends.Then it introduces the common positioning technology.At last it introduces classical positioning algorithm based on WLAN and improved algorithm with emphasis.RSSI can easily bring significant propagation loss affected by the environment.Only considering the RSSI value between two nodes to measure distance may bring large error,which can bring significant difficult to location.So we should correct ranging distance between unknown node and every beacon node before location.Aimed at this,analyzing the traditional difference correction localization algorithm,this paper proposes an algorithm based on joint ranging correction of neighbor node,using appropriate ranging correction coefficient to correct the RSSI ranging distance.Then it uses the improved PSO algorithm with better convergence performance to optimize the location result.After Getting the more appropriate ranging correction coefficient,this paper proposes a new feedback target function based on ranging correction coefficient by analyzing the traditional PSO character.Then it uses the PSO algorithm with fission competition mechanism to optimize the location result.The experiment result shows that these two improved location algorithms not only can highly improve the location precision,but also have certain adaptive capacity to environment.These two algorithms can effectively increase the location precision and stability.In this paper,the research and experimental equipment of APs are TP_LINK WA510G+wireless routers,and the terminal is HUAWEI smartphone.We use these to collect the important node information. |
