Design And Implementation Of DSP-based GSM Base Station Information Monitoring Device

By the end of 2014, China had more than 600 million GSM network users. As a relay station, GSM base station directly affects the GSM network communication. Therefore, the normal operation of the GSM base station must be assured. Monitoring the information transmitted in downlink is an essential task in the field of mobile communications. Developing a GSM base station information monitoring device was just the main content of this research.GSM signal processing theory was briefly analyzed in this thesis, including GSM system structure, air interface theory and signal processing procedure. Meanwhile, a practicable scheme was presented for the design of GSM base station information monitoring device. For the design of hardware system, firstly, SAWF module and RF receiving circuit module was analyzed, thus the AD6548-based GSM receiver circuit was implemented. DSP minimum system was analyzed as well as the A/D conversion module, Bootloader module, SDRAM module, etc. Accordingly, baseband signal processing module circuit was completed. The software system design thought was also analyzed in detail. Firstly, derotation algorithm was proposed to eliminate complex operation in channel equalization. Then sliding detection algorithm was analyzed to ensure that FCCH and SCH were captured. It was for system synchronization, including frequency synchronization and time synchronization. Correlation algorithm was proposed afterwards for channel estimation, which was utilized in matched filtering and channel equalization. After that, channel decoding algorithm was analyzed, followed by de-interleave, de- multiplexing, decoding convolutional codes, and C RC check. Finally, the BCH information was generated. In addition, in order to interpret the BCH information as well as communicate with PC, serial port function and GUI of the host computer was also designed.Processing method of GSM physical layer received signal was systematically analyzed in this thesis. SDR as well as mobile communication technology was utilized. In the end, systematic test was adopted to prove the validity of the design. Further suggestion for the future research was given as well.