Linear Frequency Modulation-based Ultra-wideband Wireless Location

In recent years, due to the huge community demand in the short-range wireless communication and positioning, great strides in micro-electronics, RF and other hardware technologies, the ultra-wideband (UWB) system gradually becomes a research hotspot. The linear FM signal (Chirp) Ultra-wideband which is concerned in this thesis is one of them. Because this system has many advantages, including a high resolution of multipath, long transmission distance, strong penetration, anti-interference and anti-Doppler frequency offset, small Peak-to-Average Ratio, low power consumption and other advantages, it's very suitable for indoor and outdoor positioning in the short-range. In this thesis, ultra-wideband positioning is used in small-scale spatial such as stations, airports, shopping centers, schools and hospitals. Because of the high reliability of the positioning, the results can be used for tracking, guidance, fire rescue, counter-terrorism or other emergency services.This thesis studies how to use the Chirp UWB to positioning, while the key to the positioning is accurately measure the time difference of arrival (TDOA) of the signal. Directed towards the UWB channel models which is close to the realistic propagation environment, some important tasks which are based on various existing algorithms about delay measurement and positioning is focused on in this thesis, such as follows:The relevant background of the Chirp UWB is introduced, then the principle of the Chirp spread spectrum and the time-delay estimation algorithm based on signal pulse compression is detailed. For the same UWB channel, some Chirp signals which has different bandwidth are used in simulation. Simulation results show that the performance of this algorithm is closely related with the bandwidth of the Chirp signal. It's suitable for the application of positioning when the Chirp signal has a large bandwidth.The concept of higher-order cumulant is introduced, and the fourth-order cumulant of the Chirp signal is calculated. The fourth-order cumulant TLS-ESPRIT algorithm based on fast pseudo-spectrum amendments is proposed. First through TLS-ESPRIT algorithm an initial time-delay estimation is used to determine the range which is relatived to search peaks of the spectral. Then MUSIC algorithm is utilized to amend the preliminary results, while excluding virtual path. MATLAB simulation results show that when the bandwidth of the Chirp signal is small and the channel includes colored noise, the new algorithm perform well. Meanwhile, three relationships which three key parameters need to obey is pointed out in this thesis when the Chirp signal is used in simulation and engineering applications.The relevant content of the multi-stage Wiener filter is introduced, and the fourth-order moment matrix of the Chirp signal is derived. Then the coherent MUSIC algorithm based on the multi-stage Wiener filter is proposed. This algorithm uses the basic multiply-add operation so that avoiding the eigenvalue decomposition which always exists in the super-resolution algorithm. The new algorithm reduces the computation and facilitates the realization of the hardware processing. When the bandwidth of the Chirp signal is small and the channel includes white noise, the simulation results show that the new algorithm retains the superiority of the coherent MUSIC algorithm under the premise of the significant reduction of computational complexity.Finally, these algorithms for time-delay estimation proposed in this thesis are utilized to measure TDOA. Then four algorithms for wireless location are used to process the data of TDOA. The simulation results show that these previous methods can accurately measure TDOA which is the foundation of obtaining ideal results wireless location. The same time, simulation results indicate that the suitable algorithm for positioning is relative to the bandwidth of the Chirp signal.