A Radio Channel Sounder for Mobile Millimeter-Wave Communications: System Implementation and Measurement Assessment

We describe a state-of-the-art channel sounder to support channel-model development for mobile millimeter-wave (mm-wave) communications. The system can measure the complex amplitude, delay, and angle of arrival of the multipath components of indoor and outdoor channels. Specifically, a custom multiplexer (MUX) records the channel impulse response across a 16-element receive (RX) antenna array in 65.5 mu s, while the channel is static. The delay resolution of the system is 1 ns and, because the elements are oriented in a 3-D space, both azimuth and elevation angles can be extracted. The robust link budget, comprising high-gain directional RX antennas, enables indoor link measurement beyond 150 m in line-of-sight and 20 m in non-line-of-sight conditions. The RX array is mounted on a location-aware robot, which is battery operated. Combined with the speed of the MUX, untethered acquisition of mobile-channel data is possible. To the best of our knowledge, this paper contributes the first sounder that is capable of mobile measurements at mm-wave frequencies. The hardware implementation of a functional 83.5-GHz system is described in this paper, and some illustrative results, including small-scale statistics and Doppler, are presented.