| The analog cellular mobile communication business developed very quickly, but as the business increased, the lack of communications capacity soon exposed in some developed countries. Therefore, people began to seek a new mobile communication system with greater communications capacity and fit for data communications. GSM was born in such circumstances. Voice communication is the most basic application of GSM. The paper analyzes the voice communication protocol, and presents the realization of the software system for mobile terminals.The paper first introduces GSM development history, identity and digital mobile communication systems, cellular technology related knowledge, featured GSM typical architecture, given its structure map, and all related subsystems and communication interfaces between the entities.Chapter III presents GSM voice transmission process. In wireless interface, voice is sent out after modulation through a series of processing. Then the full rate speech processing functions on the terminal is introduced.The last part describes software system design on the terminal. First the analysis of the platform is done, including hardware and software system structure, design methods and the effect achieved. Next the hardware structure is briefed, which is stressed on the software systems design. For the software system, the structure of the software system is introduced, and for voice communication, the call control software design is presented, including the definition, the overall structure and the state. Then the signal processing is discussed from the normal and unusual aspect. At the end there is the test for the terminal, which is consistent with the requirements. |
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