Research On Ultra-wideband Positioning Based On Compressed Sensing

Ultra wideband(UWB)technology is widely used in short range positioning technology because of its strong multipath resolution capability,including indoor ultra wideband location.Because the ultra wideband signal has very wide bandwidth,the sampling rate of the receiver will be very high if it follows the Nyquist sampling rate.Thus not only the receiving node ADC module design costs but also the difficulty of hardware design will be increased.The compressed sensing(CS)technology provides a convenient solution to the high sampling rate of UWB receivers in recent years.By applying compressed sensing technology to the UWB positioning system,the problems caused by the high sampling rate of the receiving node can be effectively solved.The main contribution of this thesis is as follows:Firstly,in order to solve the problem of high sampling rate in UWB positioning system,an ultra wideband positioning system based on compressed sensing is proposed.The positioning system is composed of two steps: The first step is to use compressed sensing technology to estimate the impulse response which including the time delay information of the target signal at low speed.The second step is to extract the TOA information from the impulse response by using the TOA estimation algorithm.Then,an UWB TOA positioning algorithm based on Compressed Sample Matching Pursuit(CoSaMP)reconstruction is proposed,using CoSaMP to complete the impulse response estimation step in this algorithm.Then the target diameter is extracted by setting the threshold in the TOA estimation process.Based on the threshold TOA estimation algorithm(AMMR-TOA),an improved threshold estimation algorithm based on the maximum value ratio of energy GAMMR-TOA is proposed.In the GAMMR-TOA algorithm,the influence of the strongest path and the weakest path is taken into consideration when setting the threshold,which makes the mean value of the maximum value of the energy reflect the channel characteristics and the signal to noise ratio.Thus more accurate TOA information can be obtained.The UWB TOA positioning algorithm based on compressed sample matching pursuit(CoSaMP)reconstruction is simulated and analyzed to verify the localization performance of the algorithm.Finally,in order to solve the problem that the traditional greedy algorithm cannot estimate the impulse response accurately and the multipath signals received by thereceiver in the actual channel are unknown when estimate the impulse response based on compressed sending,we propose an improved high precision compressed sensing UWB location algorithm HSRMP-GAMMR-TOA.The algorithm can reconstruct impulse response under the condition of unknown sparsity.In the step of choosing the best atomic,the generalized Dice criterion is used instead of the inner product method used in previous reconstruction algorithms,which makes the step of choosing atomic more rigorous,and can estimate the impulse response more accurately.Simulation results show that the algorithm can achieve better positioning results.