The major part of the outdoor locating systems can be categorized into the following two approaches. One is based on the global positioning system (GPS), the other is based on the cellular network system. Although the approaches of these two major systems have been shown to be effective in outdoor environments, their positioning capabilities are limited in indoor or Non-Line-of-Sight (NLOS) environments due to the received signals too weak to provide accurate position. Additionally, their RSSI is variable due to multiple reflections and refractions of the signal, respectively. For the purpose of better positioning and tracking services, it is necessary to develop appropriate algorithm to estimate the location of a mobile station (MS). In this paper based on IEEE 802.16e WMANs (Wireless Metropolitan Area Networks), three positioning methods for three scenes were proposed in terms of the relative location between Base Station, Fixed Relay Stations, and Mobile Relay Station, and a Multi-hop method for when the MS cannot receive GPS signals or the weather is unfavorable.
['Sheng-Cheng Yeh', 'Chia-Hui Wang', 'Wu-Hsiao Hsu', 'Ming-Yang Su']
The Research of Locating Methods for Mobile Stations Based on IEEE 802.16e Multi-hop WMANs