A Millimeter-Wave Phased-Array Channel Sounder for Double-Directional Communication and Localization Channel Descriptions

Knowledge of the properties of millimeter-wave (mmWave) propagation channels is important for the development and deployment of 5G and 6G wireless systems. This article presents a channel sounder that allows mmWave channel measurements that are double-directional, ultrawideband, real-time, and optionally multilink. The sounder is based on the principle of beam switching; it provides 51-dBm EIRP and can scan with an Field-of-View (FoV) of 360° on both the Transmitter (TX) and Receiver (RX) sides. It achieves an Multiple Input Multiple Output (MIMO) snapshot acquisition time of 2.4 ms and can gaplessly stream/record the received signal for up to 8 s. During this time, up to 768 angular combinations per MIMO snapshot are recorded with a 2- $\mu $ s multitone waveform with 1 GHz of bandwidth. This bandwidth results in a delay resolution of 0.3 m with a maximum detectable excess delay of 600 m. The number of angular combinations can be increased in exchange for a longer MIMO snapshot time. The sounder also features a multinode configuration that allows simultaneous measurements with three spatially distributed TX locations. We also present the timing methodology and FPGA implementation developed to fully exploit the capabilities of the switched-beam arrays, as well as the sounder calibration methodology. Example measurements demonstrate the capabilities of the sounder.