Research On Ray Tracing And Localization Techniques In Mobile Communication Systems

With the development of mobile Internet, demands of new service are being generated constantly in mobile communications, which pushes the advancement of communication technologies and the evolution of wireless networks. How to accurately predict wireless signal propagation property has been a key topic in wireless network planning. The ray tracing technique can simulate the propagation process of each ray, predict the propagation properties of signal, such as delay and propagation loss, and build a determined wireless channel model via computer simulation. Its effectiveness and accuracy are superior to conventional actual measurement or physics model.In terms of services, the location-based service (LBS) has gradually been the new hotpot in the research of mobile communications and the localization technique is the technical prerequisite of LBS. According to application scenarios, the localization technique is divided in two groups, the outdoor localization and the indoor localization technique. The outdoor localization is being mature gradually due to the generalization of the Global Positioning System (GPS) technique and cellular network-based localization technique. However, as to the indoor localization, GPS is not applicable in indoor environments because the satellite signal cannot penetrate building materials and neither is cellular network-based technique due to the complicated structure of indoor scenarios and the resulting severe multipath fading of signals. The location fingerprint technique and propagation model technique are two common indoor localization techniques. The latter usually provides a poor accuracy, which can be improved by incorporating the adjustment of propagation model provided by the ray tracing technique. The former can also make a use of the ray tracing technique to accomplish the manual fingerprint sampling work through computer simulation.This paper studies the tetrahedron meshed ray tracing (TMRT) acceleration technique and its corresponding maximum empty sphere Delaunay tetrahedralization method, aims to solve the inefficiency of conventional ray tracing techniques. A simulation platform is designed to testify the acceleration effect of TMRT and the subdivision efficiency of the tetrahedralization method. In respect of localization, this paper studies the status quo and drawbacks of traditional indoor and outdoor localization techniques, as well as the new Radio-Simultaneous Localization and Mapping (SLAM) technique which is applicable to fully unknown indoor environments. Similarly, a simulation platform is designed to testify the accuracy of this method. On account of the strict requirement of application in unknown environments and the pursuit of higher accuracy, a drawback inevitably exists in this method, i.e. that it depends on the user periodically revisiting previous locations. This paper, in the end, proposes a future solution to this drawback, the ray tracing-based Gaussian Processes Model. In this solution, the ray tracing technique can decrease the workload of the manual sampling work, higher the model accuracy and consequently higher the localization accuracy.