The project «RadCom» – Sensory Analysis and Communications embark on a collaboration
At the beginning of November 2023, a principle experiment took place at armasuisse Science and Technology (S+T) to combine communications and radar functionality in the same device and with the same emissions, in cooperation with the company PrecisionWave AG. This principle experiment demonstrated the basic feasibility and at the same time tested theoretical performance limits in field experiments.
Sarah Trösch, specialist area Innovation and Processes and Roland Oechslin, specialist area Sensory Analysis, competence sector Science and Technology
The goal of the project «RadCom» (short for radar and communications) is to combine the radar and communication functionalities. This is interesting because free frequencies are becoming increasingly scarce and wireless applications are becoming more and more widespread. In addition, one single device with just one antenna could thus be used for several functions such that integration on a vehicle would also be simpler, for example.
In 2021, armasuisse S+T launched a research project on the subject of radar and communications – called «RadCom» for short. Together with the Fraunhofer Institute FHR, various studies have been produced on the compatibility of radar and communications in one device as well as their possibilities and limitations. The theoretical findings were now to be checked in the field by means of a principle experiment. The starting point of this principle experiment presents the question of how the radar and communication functionality can be covered with the same device as well as the same emissions. However, as the requirements for both functionalities are different or sometimes even contradictory, a compromise needs to be found in the transmitter and receiver hardware as well as in the signal form.
The goals and requirements of the principle experiment
The company PrecisionWave AG originally developed the radar network «miniCODIR» for the research project «Cognitive radar». It consists of four transmitter and receiver nodes. These radar systems have been specially designed such that they can be adapted to different purposes by software. For the «RadCom» principle experiment, two «miniCODIR» nodes were configured as a transmitter/receiver pair. The transmitter node illuminates a target to be monitored and evaluates the signal reflected by the target, known as monostatic radar functionality. The receiver node evaluates both the signal transmitted directly by the transmitter, in other words, the communication functionality, as well as the signal reflected at the target, known as bistatic radar functionality. The goal of the experiment was to find out which transmitter signal forms, in other words, emissions, are suitable for simultaneous radar and communication operation. Typical metrics such as the probability of detection and the position accuracy with the radar, or the frequency of transmission errors at communication, enable this to be quantitatively evaluated.
The dilemma in choosing the signal form is that on the one hand, a suitable radar waveform cannot transmit a lot of data on the communication level. On the other hand, an ideal waveform for communication, such as with a mobile phone in terms of data transmission, is not optimal for radar operation. The aim is therefore to find out where the optimum, in this case the balance, lies, depending on the area of application.
The test procedure of «RadCom»
In the principle experiment, the transmitter and receiver nodes were positioned about 100 metres apart. Both nodes were connected to a central control computer which also saved the recorded measurement data. The two nodes were also aimed at the test area which was monitored by the radar functionality. The radar functionality could be tested using a test target, in this case a cyclist.
In order to be able to now compare different signal forms with each other, the same test – a test round corresponds to a round with the bicycle – was performed with five different signal forms and three to four different transmission powers in each case. It can thus be quantitatively determined where the performance limits lie, both with regard to the communication and to the radar.
What’s next? – An outlook
In this open experiment, different waveform types were tested and the resulting data collected. In the next step, the data is analysed in detail. Depending on the result, it will be decided how the project «RadCom» is to be continued, in other words, which application area will be focused on in the future. For example, «RadCom» could be of benefit in the military area, by enabling the limited space on platforms to be put to better use while at the same time fewer transmissions would be generated and less maintenance work would be required.
Research Program 1 - Reconnaissance and Surveillance (admin.ch)