The Development And Soft Design Of GSM Protocol

In the past decade, wireless communication saw explosive growth and now it has been an integral part of modern life. Although today 3G communications has large network coverage, and LTE system has also been rapidly developed, the GSM system is still dominated the voice service. At present, the number of GSM’s users is still the largest, and GSM occupies the largest market. During the period of the development of 3G and 4G networks, the network must be compatible with 2G network services. The purpose of this thesis is to implement the GSM radio interface Layer 3 protocol software, which will be a part of a GSM micro base’s protocol analysis module.The design is based on the SDR platform which is composed of Xilinx’s KC705 Evaluation board and PC. The FPGA’s evaluation board performs GSM’s baseband functionalities including demodulation, and equalization. The PC is responsible for the implement of GSM’s wireless interface protocol. The FPGA packages the data from demodulator into a specific format, then send it to the PC by Ethernet interface and finally the software in the PC processes them. This thesis focuses on the architecture and design of the software on PC side. This software also supports the analysis of multi-base’s signaling. It consists of five modules: synchronization, logical channel mapping, L1 channel decoder, the parser of LAPDM protocol, L3 message parser. The synchronization module’ main job is to complete the synchronization of normal burst by parsing SB’s FN for every basestation. Logical channel mapping module is to distribute NB to different logical channel’s processor according its FN. L1 channel decoder module is mainly to decode NB into L2 frames or L3 frames upon the type of logical channel. The parser of LAPDM protocol is responsible for parsing multi-frame in the data link layer. L3 message parser module analyzes the specific GSM services, extracting system parameters and finally supplied the to the top application software.At the last part of this thesis, tthere are some experiments about system functions. These experiments include configuring multiple cells, signaling process monitoring cells band and verification of the system that supports FM tracking function, and finally shows that the system has been designed to meet the needs.