Joint UWB TOA and AOA estimation under 1-bit quantization resolution

UWB signal is robust for indoor dense multipath environment and has delicate time resolution. By taking advantage of these characters, indoor positioning system based on TOA and AOA measurements has been investigated. It has been shown that joint TOA/AOA estimation method has provided excellent performance for indoor localization. However, large bandwidth receiver ADC is of high hardware complexity and energy cost. Thus UWB positioning system is hard to implement in spite of its localization potential. In this paper, a 1-bit quantization TOA/AOA estimator employing an uniform linear array of antennas and high speed comparators is presented. A corresponding three-step algorithm for TOA/AOA estimation is adopted. Firstly, TOAs for array elements are estimated and then initial estimation on the first element TOA and TDOA is performed with element TOAs. At last, fine TOA and TDOA are estimated utilizing initial TOA and TDOA, the AOA is calculated through geometry relationship between array and direct path signal. Subsequently, connections between performance and estimator parameters such as element number and array size have been analyzed. At last, simulations in IEEE 802.15.4a channel model is made to evaluate estimation performance. As expected, element number and size of estimator array make great contributions to estimation accuracy. Ranging errors about 3cm and angular errors about 3° are achieved at practical SNR with 2 antennas and 0.5m in size.