NATO STO

The IST-ET-101 has analysed the relevance of the emerging in-band full duplex transceiver technology for future military applications. In-band full duplex transceiver technology here means that a device can simultaneously transmit and receive radio signals on the same frequency. The IST-ET-101’s analysis of the relevance of the emerging in-band full duplex transceiver technology for future military applications started with a discussion of two conflicting trends with respect to frequency spectrum. On the one hand, the present and future tactical communication services in NATO-led operations like NATO Response Forces (NRF), Very High Readiness Joint task Force (VJTF), Enhanced Forward Presence (EFP), and also in NATO initiatives like Federated Mission Networking (FMN) are raising more and more attention. Consequently, more military frequency spectrum is required to satisfy the information exchange needs in the wireless tactical communications domain. In addition, the information exchange needs to be protected against electronic warfare threats (e.g. intentional jamming, interception, reconnaissance). On the other hand, frequency spectrum is a scarce and limited resource which cannot be augmented. This leads to the challenge of using the frequency spectrum as efficiently as possible. Several solutions to cope with the spectrum challenge have been briefly discussed by the IST-ET-101. One of them is the emerging in-band full duplex radio technology. When designing a full-duplex systems, the intrusion of a self-interference signal in the reception path causes the key challenge. This self-interference signal needs at first to be modelled properly and secondly, be eliminated from the reception path. Several state-of-the-art approaches which have been proposed from researchers at different universities have been reviewed by the IST-ET-101. One conclusion of the group was that all the proposals have in common that they use a two-staged approach, one stage in the analog domain and another stage in the digital domain. The assessment of a relevant subset of state-of-the-art prototypes lead to two general observations: • Firstly, the feasibility of full-duplex operation has been convincingly proven for lower-power commercial mobile communication systems in a laboratory environment. The independent state-of-the-art prototypes around the world achieve beyond 100 dB of total self-interference cancellation (SIC), even with rather large operation bandwidth (up to 80 MHz). • Secondly, almost without exceptions, the existing experimental research is limited to the 2.4 GHz industrial, scientific, and medical (ISM) band. From these two observations it follows immediately that • the results need to be confirmed under realistic conditions in field environments for a selection of relevant operational scenarios. • further research is still needed to confirm the prospects of full duplex radios • at lower military frequencies, e.g., at HF, VHF and UHF. Although modulation bandwidth is typically much smaller