Besides the evaluation of these basic factors, protocol performance is of equal importantance. This has to do with how efficient frame and character synchronization is, how effective error control works, and how successful protocol adaptation actually is. Although some of these tests may be done by on the air tests, however, HF propagation conditions are almost impossible to repeat thus there is not really a chance for making comparitive tests this way. What really is needed is a means to create an artificial ionospheric test medium that can be reproduced at will. Only then is it possible to set up norms and milestones for performance evaluation.
Computer simulation is one way to obtain quantiative results.
A simulation study based on theoretical concepts can provide the basis for establishing expected performance characteristics, also serve as a guide as to requirements for hardware and software expectations. It can provide an essential justification for continuing development work without the risk. During test and development phases, real-time testing using an HF channel simulator is essential. Ionospheric Reflection Model HF communication is typically characterized by multipath propagation and fading. Transmitted signals travels over several propagation modes to the receiver via single or multiple reflections from the E and F ionospheric layers.