Research On Radiolocation Based On CDMA And Its Application Of Monitoring System For Vehicle Terminal

With the development of communication technology, especially the cellular communication, the research and application about radiolocation based on network become highlighted in recent years. Due to the government's demand and market requirement, the high precise position by network becomes a focus under the complex wireless environment. In this thesis, we analyses the theory and methods in this field, quiet in details. Aiming at the influence of non-line-of-sight, we also discuss it theoretically, introduce a conception of correct coefficient, and present an algorithm to estimate the coefficient. And a position scheme is also realized in our vehicle terminal monitoring system based on CDMA.The main work as follows:Firstly, we analyzed all kinds of radiolocation methods systemically, especially the TOA or TDOA based on time. We also discussed the influence of several adverse factors theoretically, such as multipath, non-line-of-sight propagation. Comparing with these ready-made algorithms, this dissertation introduces the conception of correct coefficient, and presents a nonlinear least squares solution to estimate the coefficient, to obtain the more precise distance under the non-line-of-sight environment. This method is restrained from NLOS propagation.Secondly, under the Linux operating system, we quite completely discussed the realization of CDMA services. According to the dada transmission character, the feasibility of which the position service and the video data about the vehicle terminal can be transmitted on the CDMA1X network is analyzed in detail. And the CDMA1X service is also realized on the operating system.Finally, as for the ready-made network structures for radiolocation based on CDMA, we compared with each other, and gave the position service procedures. To satisfy our system's demand, we adopted the famous scheme of gpsOne, selecting a CDMA modem with the capability of radiolocation, correspondingly. We also built a vehicle terminal communication system with the positioning and monitoring capacity, obtaining the position information from the SMS.