Linear Fm Signal-based Positioning Technology Research

Along with the increasing positioning accuracy requirements, the Chirp signal has become an important new positioning technology in wireless communication. Because the signal has the advantages of: high accuracy, lower power consumption, high penetration, it is very suitable for tracking range, positioning in high dense multipath environment as indoor, and it has been widely studied and applied. And the Chirp LFM signal has the advantages of far transmission distance, high precision, easy self-coherent demodulation, strong anti-mutipath capability, lower-emission energy, low cost. So the Chirp signal is suitable for precise positioning of small-scale in indoor room, airport, hotel, and so on. On the basis of the inherent advantages of Chirp signal, this article combines with some other algorithms to make the Chirp positioning have a more superior performance. These algorithms can be used in wireless location, channel estimation, measurement, tracking, etc.This article makes a thorough study on Chirp signal positioning technology. Because there are some short-comings in the exiting location algorithms, such as the low resolution of the correlation algorithm, volume measurements of signal fingerprint or signal map, etc. The algorithm making spectrum analysis to channel impulse response to estimate the channel is proposed. The stretch processing algorithm of Radar location is applied to get the frequency spectrum. And the ARMA spectral estimation algorithm is used to get a high resolution. Then, based on Chirp positioning technology,combining UWB pulse transmission technology,a new wireless communication system positioning method: applying time reversal technique to obtain the distance difference is introduced. The algorithm does time reversal pretreatment to the channel impulse response from the communication station to the positioning station; then, the time reversed signal is launched to the positioning station by the mobile station. Due to the self-focusing of time reversal technique, the two channel impulse response completed a correlation operation. The distance from the mobile station to the positioning station can be determined by the correlation peak; the distance equations can be established to calculate the mobile station location, too. This new positioning method avoids the impact of NLOS better.