Deriving 2D TOA/TDOA IEEE 802.11 g/n/ac location accuracy from an experimentally verified fading channel model

In indoor environments Received Signal Strength Indicator (RSSI) values are strongly affected by multipath propagation effects resulting in a location accuracy that is often not very reliable. More accurate ranging techniques such as Time Difference of Arrival (TDOA) could be integrated into IEEE 802.11 g/n/ac chip sets requiring hardware modifications. Performance evaluation of five TOA/TDOA estimation algorithms (IFT, group delay, ESPRIT, MUSIC, MinNorm) is carried out employing a stochastic radio channel model conform to WiFi g/n/ac. Mean errors and standard deviations are calculated as a function of coherence bandwidth and Rician K-factor. Localization performance parameters are validated by various measurements in indoor environments. Based on an experimentally verified 1D-simulation model the 2D-location accuracy has been evaluated. It can be shown that even in case of moderate system bandwidths and low Rice coefficients, i.e. WiFi n-std and K > 1, location accuracies in the sub-meter range with TOA setups can be obtained. Typically location accuracy achieved with TDOA setups is only half of the accuracy that can be achieved employing TOA systems. But even in this case significant improvement compared with RSSI-methods for WiFi n/ac could be achieved.