Performance evaluation of a LEO system in urban/suburban environments in Ottawa, Canada

The performance of a LEO system (Globalstar) in downtown Ottawa (urban) and Bells Corners (suburban) was evaluated by predicting fade statistics using an expression that combined three statistical channel models into a single function and incorporated the average probabilities of being in a line-of-sight (LOS), shadowed or blocked path state to potentially visible satellites. The path-state probabilities were derived from a combination of digital hemispherical photographs taken in both environments with simulated look angles to the Globalstar satellites. Photo sets were taken at head-height, at above rooftop-height, and with the camera mounted on top of a van in order to simulate reception by pedestrian, residential, and mobile users. Fade cumulative distribution functions were calculated for every photo set, assuming operation with the single best satellite (in a LOS position) or the one with the highest elevation angle. A satellite diversity analysis found that substantial reduction in fade levels could be obtained by using this technique in downtown Ottawa and Bells Corners.