MIMO channel sounding taking into account small angular spread

The use of multiple receive antennas as well as multiple transmit antennas has attracted worldwide attention to extend the performance of existing mobile communication systems. Therefore, it is of great importance to know the features of the real propagation channel. The real propagation channel is investigated by MIMO channel sounding, where high-resolution parameter estimation schemes are used to resolve the physical channel with respect to its spatial (and temporal) structure. However, due to narrow diffuse scatterers, the commonly used model of discrete wavefronts is no longer valid. We introduce a simple approach to model wavefronts with small angular spread. Additionally, we show that the ESPRIT (estimation of signal parameters by rotational invariance techniques) algorithm with a slight modification is applicable to estimate the direction of arrival and the angular spread jointly. The approach is based on the assumption of Gaussian distributed wavefronts.