Research And Implementation Of Dynamic Channelization In Software Radio

With the rapid development of multi-standard,multi-mode,multi-systerm communication and front-end receiving technology,the band of receiving signal is wider and wider in SDR(software defined radio)systerm.The received IF(intermediate frequency)signals are often contain multiple sub-signals with carrier frequencies uneven distribution and different bandwidths,which vary randly in the process.To solve this problem,the dynamic channelization is needed,which is able to extract or separate sub-signals from the IF wideband signals.In the absence of sub-signals priori information,this dissertation is focusing on dynamic channelization technology,the contents are as follows:1.For receiving the multi-signal dynamicly in SDR systerm,the existing dynamic channelization architecture is improved.Based on the analysis of existing dynamic channelization architecture with subband decomposition,it is improved by considering complex exponential modulated filter bank as analysis and synthesis filter bank.Simulation results show that the improved dynamic architecture needn't to design the complex perfect reconstuction filter bank and can reduce the overhead of reconfigurable and the difficulty of implementation.2.There is a pheonomena that it is hard to detect transition band because of the different of subband spectrums of bordband signal crossing channels in dynamic channelization.In order to resolve this problem,a method of subband spectrum sensing based on double thresholds of power is proposed.Firstly,the decided subbands and doubtful subbands are detected by setting the double thresholds of power.Then the doubtful subbands are detected further with their square spectrums,because the nonlinear character of power will improve the difference between signal and noise.The result of simulation shows that the new method is a balance between performance and computational complexity,so it is suitable for dynamic channelization which requires better performance and real-time processing.3.The FPGA implementation of dynamic channelization are researched based on its theory.Firstly,the system structure of dynamic channelization is designed and the implementation of every function module is given,combined hardware features and the design principles of FPGA.Then the systerm is simulated using the method of ISE-ModelSim-MATLAB.Finally,the feasibility of implementation scheme is verified through the hardware test on the digital signal processing platform based on VPX bus standard.