Digital IF Receive System For Wireless Communication

With the rapid development of communication technology, wireless communication becomes more and more integrated and individualized. Its speed becomes higher and higher. Now there are several communication standards in current communication system. It is difficult to make these standards be compatible. As a good solution to this problem, Software Radio(SR) has became the focus of research. Software Radio makes the communication system break away from application-oriented design method. Therefore SR has been recognized as the next major leap forward in wireless communication.Softwar Radio is a new architecture of wireless communication. The Intermediate Frequency (IF) part in SR is different from that in tranditional communication system. IF is digitized totally in SR. As a result, we can use advanced and mature Digital Signal Processing(DSP) technology to realize system. Furthermore digitalization can conquer some disadvantages in analog IF system. There are several methods to implement DSP, such as using traditional Digtial Signal Processors(DSPs). When it comes to FPGA/CPLD, due to its programmability, system implementation with it is flexible. Therefore engineers can design hardware system with software method.The focus of this paper is how to implement the digital IF in wireless receiver efficiently.The main content includes:1. Introduce general algorithms in DSP and simulate the key algorithms with FPGA.2. Research the digital quadrature demodulation. Firstly analyze several demodulation methods and give out their advantages and disadvantages. Then bring up a effecient method to implement digital IF system and simulate it with EDA tools.3. Research multi-rate theory. The emphasis of research is decimation technology. Design CIC filters and Halfband filters with this theroy.4. Simulate the core parts of digital IF system with software Matlab and Maxplus.5. Pay most attention to the implementation of digital IF system with smaller scale and higher speed in FPGA.The original contributions in dissertation include:1. After analyzing several methods of digital demodulation, implement the digital demodulation more efficiently.2. Apply truncation theory and design multi-stage CIC filters with higher efficiency.3. Design multi-stage decimation system on the basis of Halfband filters and CIC filters.