Channel Sounding



Vehicular-to-vehicular (V2V) communication will play an important role in future safety-related traffic applications, since it enables direct information exchange between vehicles without line-of-sight. Highly reliable wireless communication links are key components for these applications. Those are in turn directly dependent on the propagation channel, the received power and the destructive fading effects of the channel. Probably the two most distinctive characteristics of V2V channels are the low position of the antennas and the time-variant radio properties, due to the movement of transmitter, receiver and scattering objects. These characteristics lead to, among others, fast MPC shadowing effects and diverse Doppler frequency distributions. To get a better understanding of the multipath process in vehicular communication scenarios, thorough analysis of measurement data from channel sounding campaigns is necessary.

The HHI Car2X channel sounder, developed at the Fraunhofer Heinrich Hertz Institute, is a wideband measurement device with a bandwidth of 1 GHz at a carrier frequency of 5.7 GHz. The measurement bandwidth permits a delay time resolution of 1 ns (30 cm of wave propagation) and therefore a highly resolved view into the behavior of MPCs. The main advantages of a wider measurement bandwidth are the high delay time resolution of individual multipath components (MPC) and the reduced sensitivity to small-scale fading effects, due to a lower number of superimposed MPCs per delay time bin. Another benefit of highly resolved wideband channel data is the ability to relate individual MPCs to physical scattering objects. 

We offer an extensive data set of more than 100 measurement runs from nine relevant vehicular communication scenarios at selected measurement sites in or around Berlin. In addition, we offer highly sophisticated post-processing algorithms, statistical channel analysis tools and measurement-based ray tracing method, in order to estimate reliably the position of the scattering objects.



Massive-MIMO (M-MIMO) has significantly gained attention in the 5G ecosystem. In order to realistically evaluate the expected system behavior in terms of system-level sum data rate, users block error rate (BLER), or the amount of simultaneously active users, we need to ensure that the radio propagation is modeled accurately. Here, at Fraunhofer HHI, we offer our channel sounding expertise to deliver raw measurement data, but also develop and validate channel models for M-MIMO. This encompasses extensive measurement campaigns in urban, rural or indoor environments. Self-developed measurement equipment like the HIRATE channel sounding system in conjunction with switched array antennas enable us to measure directional channel impulse responses with high accuracy.


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.