Experimental analysis of the use of angle of arrival at an adaptive antenna array for location estimation

This paper presents results of an adaptive antenna measurement platform for DCS1800 frequency division duplex operation. A description of the measurement site in central London, UK is followed by a brief note on the data available and used for post-processing in this paper. Frequency division duplex operation is analysed in terms of the estimated peak-energy spectral energy density `look-direction´ in the uplink and downlink channels and compared to GPS estimated positions of a mobile transmitter. Singular point measurements from two specific locations in central London are analysed in terms of delay, Doppler and angular spread. It has been found that the speed of the mobile to duration of the measurement period ratio determine not only the fading statistics but the correlation in the uplink and downlink AOA estimates. Statistical analysis of the angular accuracy of the uplink direction estimate to the GPS estimated angular estimate shows a standard deviation of 35 degrees. It is possible to conclude that DOA based location estimators in a highly scattered environment and using four antenna element panels will be inaccurate to such an extent that DOA based location estimation is probably not viable for E911 requirements in an European context. This location estimate at the 67% percentile is within an angle error, with respect to the `true´ GPS estimated angle of arrival, of ±12 degrees for high mobile speed/measurement period duration ratios and ±30 degrees for all mobile speeds