r estimation of compared with results of a RT tool, proving that the the directions of departure, directions of arrival, propa- adaptation of the algorithm works fine. gation delays, Doppler frequencies, and polarisation Another tool is described in [HaTa03a]: the UWB- matrices of individual paths propagating between the SAGE algorithm. This algorithm divides the measured transmitter and the receiver sites. Experimental in- data into individual ray paths and estimates the vestigations in a non-LoS pico/microcellular environment directions of arrival, the propagation time and the vari- show that the polarisation characteristics of individual ation of the amplitude and phase during the propagation propagation paths can be related directly to the types of for each signal. Simulations prove the quality in simple interaction that the waves experience along their paths, indoor propagation environments. such as reflection, diffraction and scattering. Also the signal model can be extended. In [VeLC03b], An ambiguity problem in estimating Doppler fre- for the evaluation of the extracted values, the results can quency and directions is analysed in [YiFS03] and be compensated for the influence of spherical waves. [PPYF04]. This problem occurs when high-resolution Different simulation parameters are discussed: the ex- channel estimation methods are implemented in the tension of the measured bandwidth, the frequency reso- channel sounding using a switched timing scheme. lution, the geometrical antenna array size and the number Theoretical analysis clarified that the switched timing of antennas. With an appropriate choice of the measure- schemes adopted in such systems can be constructively geometry and parameters, one can conclude that the incorporated into the ISIS algorithm. This attribute SAGE algorithm can compensate for the properties of allows performing the Doppler frequency estimation in spherical waves. This knowledge is taken into account in a large scope and high resolution without the ambiguity [VeLC03a], where me