The Design And Implement Of CDMA Communication System Based On The Software Defined Radio Platform

Software defined radio technology because of its adjustable parameters, upgrading and maintenance convenience, and compared to traditional hardware flexibility, making it the third-generation mobile communication systems one of the key technologies.Meanwhile,on January 7,2009,ministry of Industry and Information technology award 3G mobile licences to China Mobile,China Telecom and China Unicom,with the restructuring of the three opetators in china,people pay more attention to the technology of CDMA (Code Division Multiple Access)over again.this thesis design the hardware circuit of CDMA Communication System based on the software defined radio platform with the core of "FPGA+DSP", include some external dedicated AD, DA chips and memory chips, etc.And then based on this hardware platform, designed CDMA digital and voice transmission system.Including PN sequence and Gold sequence generation, spreading and despreading, onvolutional codes encoding and decoding, Interleave and De-Interleaver,BPSK modulation and demodulation, Finally, debugging the system to complete the entire CDMA communication process.Innovation of this paper in the following two aspects:(1)In structure design, this platform with the core of "FPGA+DSP", specially equipped with a microcontroller used for program storage, can be one-off all the programs stored in the MCU, the Then according to individual need for DIP switches to select the program to avoid duplication download caused some of the chips and other artificial burning accident to ensure the stability of the system.(2)In program inplement of getting Carrier Synchronization, this thesis Presents a CIC filter to replace the loop filter,Save FPGA resources largely.The key part of this thesis is the hardware and FPGA implement of CDMA Communication System based on the software defined radio platform,complete the design of each module in CDMA communication system by Verilog hardware description language, meanwhile, The programming design and simulation is completed under QuartusⅡand Modelsim emulation software platform(Synthesis tools use QuartusⅡ8.1, wave simulation tools choose ModelSim SE 6.1f).