Research And Implementation Of Weak Signal Acquisition Algorithm For TC-OFDM Indoor Location Receiver

With the rapid development of society and economy,Location Services(LBS)play an increasingly important role in people’s daily life.GNSS(Global Navigation Satellite System)signals provide people with outdoor location services,however,it is difficult to achieve the indoor environment positioning ability.The Time&Code Division-Orthogonal Frequency Division Multiplexing(TC-OFDM)system studied in this dissertation is a positioning technology based on the radio broadcast positioning system,which can realize wide-area and m-precision indoor location service.TC-OFDM systems use outdoor base stations to broadcast positioning signals while using indoor signal enhancer to increase indoor positioning signal strength and coverage.However,in some special scenes(such as fires,earthquakes),indoor signal enhancers will not be available.This dissertation presents the indoor signal acquisition methods,respectively,corresponding to the first and second category positioning receiver.When the indoor signal enhancers is not available,the problem that the positioning receiver is hard to capture the weak signal is mainly solved;In the case of indoor signal enhancers available,the signal acquisition algorithm for reduce the signal acquisition algorithm hardware resource consumption.Specific research content and results are as follows:1.To solve the problem that the first type of receiver can not capture the weak signal,this dissertation proposes a differential coherent accumulation acquisition algorithm based on noise power compensation.The algorithm estimates the noise power value from the result of the differential coherent integration,and compensates the integral result in a period by using the value,which effectively reduces the effect of the noise power on the differential coherent accumulation result.The simulation results show that compared with the existing differential coherent accumulation algorithm,the proposed algorithm can effectively enhance the acquisition sensitivity of the positioning receiver by 2dB and successfully capture the positioning signal with a CNR of 29dB Hz,which can be used in special scenes such as fire rescue.2.In order to solve the problem of large consumption of hardware storage resources in the signal acquisition algorithm of the second type of positioning receiver,a block-averaged PMF-FFT(Partial Matched Filters-Fast Fourier Transformation)weak signal acquisition algorithm is proposed.This algorithm replaces the PMF with 5-segment length in the existing system by using the block average processing module plus the single-segment length PMF to reduce the consumption of the system storage resources caused by the existing PMF module.The simulation results show that the algorithm can successfully acquisition the CNR signal of 39dB·Hz and meet the application requirements of the second type of receiver.At the same time,compared with the former algorithm,this algorithm can save 28.9%of system hardware storage resources without losing the acquisition sensitivity.3.Using FPGA + ARM architecture,built the TC-OFDM system positioning receiver verification platform suitable for the above two scenarios respectively.The two acquisition algorithms proposed in this paper are successfully implemented on the corresponding platform.The experimental results show that the differential coherent accumulation algorithm based on noise power compensation and the block-based PMF-FFT acquisition algorithm can achieve the results of simulation and verification to meet different application requirements.