Design And Implementation Of Centerless Digital Communication System Based On SDR Platform

The paper refers to the design and implemention of a special centerless telecommunication system based on SDR (Software Defined Radio). the idea of centerless exchanging, which is compare to traditional system with the center switch, is totally achieving the end-to-end communication. When the system is eliminated the the center switch, the system network is completely simpfied, and the system tends to be Interoperability, flexibility, mobility, survivability, maintainability, which is specialized in the area of field operations, field investigation, emergency fire and etc.By means of Frequency Division Multiplexing technology, the SDR value, the theory of digital signal process, and the embedded system platform of SDR (DSP with DSP/BIOS and MCU withμC/OS-Ⅱ), the system is deeply researched.the methods of the design cover the modulation of SSB, the idea of muti-telecommunication, the theory of digital processing (FFT, decimation filter, power spectrum estimation, and the thread communication of the embedded system.The system which based on SDR platform, partitions three layers: pysical layer, data link layer and application layer.this paper focuses on the two modules:on the one hand, one of the modules accomplishs the state machine function of the telecommunication protocol on the MCU, which finishs the channel established, the channel released, and the channel supervision.on the other hand, in the physical layer, the detecting module implements the real-time signal process of the channel state detection and channel scan with the theory of DSP and power spectrum estimation. Finally, we complete hardware circuit design, debugging, testing and system performance analysis, and etc.