The Research On Unauthorized Access To The GSM System

Mobile communication network in military is a fundamental facility in war fields, through which a lot of information is exchanged. Wireless access to computer network is one of the important methods of network attack and the access is under the unauthorized circumstance. In this thesis, the research object is GSM communication signals. From the intercepted communication signals, the unauthorized access to internet is researched, which build a foundation for accessing and spoofing wireless information. The thesis analyses the principles of the physical layer and data link layer of GSM system and the signal processing theories of GSM under unauthorized circumstances. Computer simulations are given to show the feasibility of these theories. The design of real-time processing system of GSM signal is introduced, which includes a real-time processing circuit, a DSP software system and a computer monitor platform. In the end of the thesis, the shortcoming in the research is summarized and the advice for further research is given.