Characterization of dense multipath effects for non-coherent GMSK wireless channels in indoor environments

This paper analyzes the effects of multipath propagation for localization of non-cooperative mobile phones (GMSK modulation) in indoor environments with reinforced concrete walls and metal objects. For localization based on Time Difference of Arrival (TDOA) calculation, cross-correlation of signals received by different sensors yields accurate propagation delays under dominant direct-path conditions. However, parameters like varying transmitter positions and frequency hopping influence the wireless channel causing systematic overestimation of calculated delays, especially under dense multipath conditions. By comparing the results of channel sounding and actual sensor data we try to characterize the non-coherent wireless channel and its multipath propagation effects with respect to TDOA correlation methods.