Virtual SATCOM is wireless communication at SATCOM speed on a HF Skywave channel without a physical satellite. The Achilles heel of modern networked warfare for mobile maneuver forces like the Navy is the communication satellite. Our adversaries including nation states, terrorist and criminals, all understand this vulnerability, and some are poised to attack this exposed capability with weapons like: jamming, cyber-attack, directed enemy, and physical kinetic attack. The DOD needs a SATCOM alternative to mitigate the space vehicle vulnerability. The ionosphere is an underutilized channel that can mitigate the risk. Our modeling has shown the ionosphere can be harnessed to communicate at long range (3000 km) and high speeds (>12 Mbps). Compared to SATCOM, current HF protocols are too slow. We are developing a Virtual SATCOM system that rides the HF Skywave channel. It is a high bandwidth HF communications channel that can match SATCOM information throughput at a reduced cost and vulnerability. RF waves in the HF band (3-30 MHz) are unique. When transmitted into the ionosphere they are refracted (bent) back to earth thousands of kilometers down range. The ionosphere is an inhomogeneous, anisotropic, nonlinear time-varying environment. Modern communications techniques can adjust to the dynamic environments. One area of our research is to provide evidence that this concept will work in the dynamic ionosphere environment. We needed a precision modeling tool of the ionosphere plasma with an iterative ray tracing simulation capability that shows channel paths from transmitter to receiver. We are using a tool called PHaRLAP to model the environment. PHaRLAP is an over the horizon radar (OTHR) program developed by the Australian Defense Science and Technology Group to analyze OTHR systems. We have modified the program to support wideband communications research. Our simulations show that an HF agile communication system can significantly improve throughput. The model ingests data from the International Reference Ionosphere to calculate the plasma grid. Our system will be able to service mobile users (e.g., maritime, expeditionary and aviation) using steerable beamforming apertures with ultra-wide bandwidth signals (3MHz). This is exciting research that can reduce cost and increase access to long range high data rate wireless communications.
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