Array measurement of the double-directional mobile radio channel
We describe a novel technique to measure the double-directional mobile radio channel. The channel is called double-directional since it includes directional spreading at both link ends, namely the base station and the mobile station. We use a double-array multiplexing technique consisting of a switched linear array at the receiver and a virtual array at the transmitter site. The measured microcellular scenarios are an open and a closed courtyard with different transmitter positions. The data are evaluated with an alternating estimation and beamforming technique that relies on (Unitary) ESPRIT estimation of positional parameters and subsequent beamforming for complex weight extraction. Usage of a two-axis crossed array at the transmitter site avoids forward-backward ambiguity. The presented exemplary results show a good agreement of the extracted directional information with the physical environment and give an indication of its scattering properties.