Research On Compression Sampling Technology Of OFDM-UWB System

Ultra wide band(UWB)is one of the 5G application scenarios and OFDM-UWB system as the mainstream of ultra wide band system,has been studied by many scholars.Ultra wide band technology brings the problem of high speed sampling,which has seriously restricted the development of ultra wideband technology.In this thesis,the theory of compressed sensing is applied in OFDM-UWB system to solve the problem of high speed and high precision ADC of ultra wide band system,and the low speed and low precision sampling of OFDM-UWB signal is realized.In order to solve the problem of high-speed sampling rate in OFDM-UWB systems,this thesis first gives analysis on the applicability of existing compressed sample methods.Then,on the basis of an established segemented observation model,it presents an optimized parallel segemented compressed sampling(OPSCS)scheme based on Hadamard matrix.The Hadamard orthogonal matrix is adopted to construct the segemented observation matrix with any dimensions,thus the orthogonal or quasi orthogonal multiplex observation sequences are obtained,and the restricted isometry property is improved.The simplified orthogonal matching pursuit algorithm is also used to avoid iterative operation.Researches show that the proposed method can effectively reduce the sampling rate in OFDM-UWB systems,and also has a good ability of noise resisting that it achieves a better system performance than the existing schemes of compressed sampling and even Nyquist rate sampling.Considering the quantization,aiming at the problem of high speed and high precision ADC in OFDM-UWB system,first of all,OFDM signal quantization noise model and the application of the traditional single-zero and multi-zero sigma-delta modulator in the OFDM signal are analyzed.Then,based on the random demodulation structure,the structure of random demodulation sigma-delta is presented.Through the simulation,we compare the performance of single-zero sigma-delta modulator and multi-zero sigma delta modulator in the OFDM signal.Meanwhile we compare the performance of multi-zero sigma-delta modulator and the structure of random demodulation sigma-delta.Researches show that the multi-zero sigma-delta modulator get better anti-quantization nosie.Under the same sampling rate,the proposed structure of random demodulation sigma-delta compressive quantization get much better performance than the multi-zero sigma-delta modulator.