The traditional mobile communications frequency bands below 6 GHz will be insufficient to meet the rate requirements of future applications and the growing number of devices. In the context of 5G development, the use of frequency resources in the millimeter-wave (mm-wave) range up to 100 GHz is therefore targeted to substantially increase the transmission bandwidths and drastically boost the network capacity. However, the propagation characteristics of mm-waves differ significantly from the characteristics in the sub-6 GHz bands. In particular, the free-space path loss as well as wall penetration losses increase substantially with frequency. To develop accurate channel models for the design, performance evaluation and standardization of 5G mm-wave technology, measurement campaigns are needed that provide detailed and reliable information on the channel properties.
At Fraunhofer HHI, we use several highly flexible channel sounder setups based on self- developed hardware and test and measurement equipment to perform channel measurements in mm-wave frequency bands up to 100 GHz. They provide large processing gains and achieve high dynamic ranges despite the high path loss. The correlation-based setups support bandwidths up to 1.5 GHz and high repetition rates to observe time-variant channels and collect large, statistically reliable data sets. Parallel transmit and receive channels enable simultaneous multi-frequency measurements, which are particularly well suited to study the frequency dependence of channel characteristics. We apply novel techniques based on rapid virtual array acquisition to gain accurate directional information with exceptionally fine angular resolution.