Statistical model for satellite to helicopter radio channel

We have developed a semi-Markov model for the satellite to helicopter radio channel at Ku band. It is a simple narrowband model to characterize signal level variations. Firstly, we performed several propagation measurements using two actual helicopters. Then, we identified three different states in the received signal fluctuation. The first one corresponds to a Line of Sight (LoS) situation, with low diffraction contributions, and hence small signal level oscillation. The second state corresponds to the obstruction of the LoS by the rotor blades, and the signal exhibits deeper fades and larger level variations. The third state occurs in between the previous two states, and corresponds to the LoS situation with significant diffraction contributions. Finally, we estimated the state parameters from the measurements. We have also considered diversity reception and assessed the performance of different diversity combining techniques.