CDMA infrastructure-based location finding for E911

This paper presents an infrastructure-based approach to handset location finding for CDMA. The issues of uplink visibility and the relative benefits of time of arrival (TOA), time difference of arrival (TDOA), and azimuth angle of arrival (AOA), and power-up function (PUF) are presented. A location simulator is discussed, which includes a cell simulator, a TOA/TDOA/AOA error simulator, and a data fusion algorithm. The cell simulator places mobiles in random locations, determines the uplink C/I at all sites, performs best server selection and uplink power control, and outputs the resulting C/I values and physical parameters to the TOA/TDOA/AOA error simulator. This error simulator adds errors to the true TOAs, AOAs, and TDOAs, as drawn from error distributions derived from time and direction estimation algorithms operating on measured channel sounder field test data. The location simulator weights and performs data fusion on the simulated, erroneous time and direction estimates from each site, to arrive at a best point estimate of handset location. It also computes error statistics. The combined simulations allow extrapolation of single-site channel sounder measurements of time and direction into multi-site location accuracy with and without PUF, and with various combinations and algorithms for TOA, TDOA, and AOA. Results in the form of location accuracy for various infrastructure antenna configurations are reported, that have been derived from measured data.