Design and Performance Evaluation of High-Capacity Mobile Troposcatter Links Under Mobility, Frequency Selectivity, and Antenna Pointing Errors

This paper presents a new approach to the design of spectrally-efficient mobile troposcatter links that are robust to mobility, frequency-selectivity, and non-ideal transmit/receive antenna pointing beams. Leveraging a well-established ITD troposcatter stationary path loss model, we introduce models for antenna pointing error and demonstrate that antenna pointing errors induce an error in the path loss that can be modeled as either log-normal or log-Laplacian. Next, we employ a single-carrier block modulation along with a pseudo-random diversity transform to create a fading resistant transmit waveform intended to exploit the channel delay and Doppler diversity. We introduce rapid physical layer retransmission protocols that adapt the modulation and coding schemes to overcome the pointing-error induced path-loss fluctuations. Via numerical and simulation results, we show that it is possible to achieve peak data rates in excess of 70 Mbps over link distances greater than 150 km on mobile troposcatter channels with a single transmit antenna, two receive antennas, and with 20 MHz transmission bandwidth.