Efficient Frequency Use for Improved Co-Existence - Final Report

The frequency spectrum is a limited resource consisting of a number of frequencies, which can be used for information transmission via radio. The Swedish Armed Forces' available frequency spectrum is limited and subject to competition from commercial interests. In order to meet the units' information needs, the number of communication systems, sensors and other emitting systems on modern platforms is also increasing, which leads to interference problems and complex system integration. It is therefore important that the frequencies available to the Armed Forces are used as efficiently as possible. This report summarizes activities and results from the R&D project Efficient Frequency Use for Improved Co-Existence (EVEREST). The EVEREST project started in January 2020 and ended in December 2022. The project has studied both technology and method to achieve more efficient frequency utilization. Examples of technologies are adaptive radio receivers in impulse-rich environments and examples of methods are dynamic spectrum allocation instead of static allocation. An adaptive radio receiver that adapts to the characteristics of the noise makes it, to a certain extent, possible to receive information in situations that a conventional radio receiver could not cope with. This technology handles impulsive interference from systems on other platforms or from the surrounding environment. Opportunistic use of TV channels gives access to more bandwidth and thus increased system capacity and the possibility to use more radio networks. If the choice is made in a good way, the extra bandwidth provides increased interference protection through the process gain obtained from a larger bandwidth. The risk of frequency conflicts in a battalion's radio network depends on the size of the brigade and battalion area, but most important is the number of available frequencies. The most important thing is to increase the number of available frequencies to reduce the risk of frequency conflicts. Initial studies of the potential and applicability of in-band full duplex for tactical radio systems within the VHF and UHF frequency bands indicate that the challenges are significantly greater than for the short-ranges systems (e.g. WiFi) that are usually discussed within the research literature. Fast frequency hopping renders additional constraints and challenges for full duplex systems. To make full duplex a viable technique for increased spectral efficiency in tactical radio networks, continued extensive research and development are required. To spread the results and create a network for future tasks, the EVEREST project has arranged two workshops where representatives from the Swedish Armed Forces, FMV and FRA have participated. Research results have been presented and discussed at the workshops and the Swedish Armed Forces have presented their experiences of spectrum management and frequency conflicts during exercises and operations, both nationally and internationally. The workshops have been highly appreciated and are expected to continue even after the EVEREST project has ended.