High-resolution radar with integrated communication

A change is currently taking place in radar technology. Analog sensors are being replaced by systems with digital modulation processes, which have a major advantage: They can also be used for communication. For some years now, intensive research has been carried out into using the OFDM (Orthogonal Frequency-Division Multiplexing) modulation method, which has been used in WLAN and LTE to date, for radar applications.

State of the art

With classic radar technology, which is based on the frequency-modulated continuous wave method (FMCW), communication is only possible to a limited extent. Due to the lack of a digital-to-analog converter in the transmitter, very small amounts of data can only be applied to the transmission signal via detours. If OFDM is used, however, the radar signal can become part of a joint communication and sensing system. The sampling rates of the DA and AD converters for OFDM radars must be more than ten times higher than for FMCW. This would be extremely expensive given the high bandwidths required for precise radar systems.

Technology

Researchers at the Institute of High Frequency Technology and Electronics (IHE) at KIT have found a way to increase the signal bandwidth in the radar channel without having to increase the sampling rates of the converters at the same time, so that very cost-effective converters can be used. For this purpose, a narrowband OFDM signal is mixed up with a frequency comb whose comb frequencies have exactly the same spacing as the baseband signal. Because only a small proportion of the possible subcarriers are used, gaps are created. These are used in the receiver to combine all subcarriers of the broadband signal in a narrow frequency band. After scanning, they can be separated and digitally recombined to form the broadband spectrum.

Advantages

The method ensures a high range resolution of the radar at favorable conditions and is versatile thanks to its digital combinability. When the new 6G communication standard arrives around 2030 at the latest, radar could be integrated into base stations to monitor road traffic, for example.

Options for companies

Increasing the bandwidth using a frequency comb is very interesting for mobile phone equipment manufacturers, but can also be used for a vehicle's communication with its environment or for monitoring a production line. In order to fully exploit the advantages of the technology, cooperation with a semiconductor chip manufacturer would also be an important step. KIT is looking for partners in these areas.