Air-Interface Protocol And Signaling Research For Mobile Communications Network

GSM (Global System for Mobile Communications) is a digital cellular mobile communications system based on TDMA. It adopts frequency hopping technology to guarantee the safety and anti-interference. After more than ten years development, it has become the foundation of China's mobile communications network. In GSM system, the mobile radio interface between Mobile Stations and Base Stations is referred as the Um interface, which can be divided in to Physical Layer, Data Link Layer and Network Layer.In this paper, the method for deinterleave and channel decoding of GSM air-interface is introduced. Meanwhile, the signaling structure and functions are substantially discussed. According to GSM protocols, we set up a static protocol and signaling analyzer to analyze air-interface signaling. Besides, by setting up channel deinterleave and decoding module and signaling extracting module, we also process the stored data from GSM air-interface and analyze the procedure of GSM voice and text messages services. Voice information is drawn out from traffic channel and can be disposed by GSM vocoder.Finally, we discussed the feasibility of the real-time processing of the GSM air-interface signaling. We also compared the differences between GSM and UMTS in terms of their air-interface and briefly discussed the procedure to obtain the UMTS air-interface signaling.The protocol analyzing system and its parameters setting are mainly referred to ETSI Technical Specification GSM 04.04, 04.05, 04.06, 04.08 and other ETSI specifications.