Exploiting Recorded Over-the-Air Transmissions to Evaluate and Optimize Military SDR Waveforms

Interoperable waveforms for software defined radios (SDRs) shall enable coalition forces to exchange tactical and mission critical data on the battlefield. Typical use cases include, e.g., voice transmission and blue force tracking. The physical layer performance of a waveform crucially depends on the applied receiver algorithms. Available physical layer communication standards, however, only specify the signal generation of the transmitter. The receiver design is left entirely up to the implementer. This makes evaluating the physical layer's end-to-end performance only based on the waveform specification very challenging. Therefore, fielding waveforms clearly requires proof of the end-to-end functionalities with practical receiver implementations. In this paper, we present and discuss an approach to analyzing and improving the performances of physical layer waveform implementations for SDRs. Our proposed method is based on over-the-air measurements in mobile scenarios. We use the NATO Narrowband Waveform (NBWF) Edition 1 according to STANAG 5630 as an example to prove our concept. For this waveform, we present practical results for different scenarios and analyze the effects of various receiver configurations. To the best of our knowledge, our results are the first to be reported on the end-to-end functionality of the NATO NBWF's physical layer from practical over-the-air tests in the VHF band. This paper was originally presented at the NATO Science and Technology Organization Symposium (ICMCIS) organized by the Information Systems Technology (IST) Panel, IST -200 RSY - the ICMCIS, held in Skopje, North Macedonia, 16-17 May 2023.