COALA - Electro-Optical MIMO Radar Systems for Autonomous Driving

Our specialist group develops highly integrated electro-optical MIMO radar sensors for applications in the field of highly automated driving in cooperation with partners from industry and research institutes. In contrast to other sensor concepts for automated driving, such as lidar (light detection and ranging), VLC (visible light communication) or camera-based systems, radar-based systems are significantly more robust against environmental influences such as ambient light, rain, snow, fog, etc.. Furthermore, radar systems are able to reliably detect objects even over very long distances. However, the angular resolution of even modern radar systems is currently not sufficient for automatic driving.

The limiting factor in angular resolution is, among other things, the maximum area of the antenna array (antenna aperture), because the larger the antenna aperture, the better the angular resolution of the radar system, i.e. smaller objects are better detected.

A major challenge here is the communication between the high-frequency radar front-ends (77 GHz radar chip with antenna) and the central station where the transmit signals are generated and the receive signals are processed. Even at moderate frequencies of a few GHz, the maximum distance between the antennas is limited to a few cm due to losses in the electrical lines (several dB/cm). In contrast to electrical lines, optical fibres only have losses in the range of 0.1 dB/km even at very high frequencies, which makes it possible to design the distance between the antennas to be almost arbitrarily large, which means that the angular resolution can be set almost arbitrarily fine.