The Study And Implementation On The Location Based On Embedded Linux

In recent years, as emerging of Internet of Things, wireless sensor network (WSN) has been widely researched in the field of communications. From the supporting technology standpoint of WSN, the embedded terminals and location information of the WSN node are the foundation of any application. This paper focuses on the double technologies, based on designing and developing the WSN node platform using S3C2440 microprocessor and embedded Linux OS, we develop the location terminal software system. The location system software is based on GIS (Geographic Information System) technology, containing GIS related functions, GPS location, and ranging location when the satellite information is missed or the satellite location system can't be used. The main ideas of this paper are as followings:First of all, we design and develop the hardware platform and software platform of location terminal. The hardware platform uses S3C2440 microprocessor which is based on ARM920T core. Two RS232 interfaces are used to communicate with GPS module and electronic compass. The software platform uses reduced Linux 2.6.13 as embedded OS. It manages the whole hardware platform and the system's bootloader, kernel, communication protocols, hardware drivers, etc. The paper introduces how to construct the cross compile platform and transplant of system or application software, and illustrates the development and improvement of Chinese input method based on embedded Linux and Qt.Secondly, on the basis of studies on researching location algorithm of WSN, a TOA-based relative location algorithm with Non-Line-of-Sight propagation considered is proposed in this paper. By exploiting the characteristics of moving unknown nodes and using its moving angle, we predict the location at the next moment, and then get the distances between the unknown node and all reference nodes. By compare the TOA distances and predicted ones, we reduce the NLOS errors and rebuilt the measuring distances, thus improve the location accuracy. The simulation results indicate the effectiveness of this method.Thirdly, location terminal communication protocol is the design and implementation of interactive interfaces among all modules. This paper implements the communication between main module of terminal and GPS module or electronic compass, which based on RS232. We also design and realize the communication protocol between Location terminal and ranging module, using Ethernet that based on UDP.Finally, develop the related software of the location terminal. Application programs of location terminal are developed using C/C++language. We use layered modular design and the design method of multi-process communication in Linux. Location algorithm is implemented using C language. GIS/GPS software, TOA ranging location software and GUI development are developed using C++ language that based on MapGIS-EMS and Qt. Application test shows that:the system can load large data maps, high work speed, low cost and portability, most of all, it can implement network node location without considering the satellite location information.In short, this location system will have an extensive practicing foreground.