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One of the major design concerns in designing a Ka-band Satellite communication system is the deep rain fades often encountered at frequencies above 20 GHz. In order to maintain reliable transmissions, certain rain compensation method must be employed. Solutions for alleviating the rain fade include adaptive forward error control, resource sharing, uplink power control, and site diversity. Oftentimes one may have to use more than one of these techniques to compensate for a large rain attenuation. The first part of this thesis dwells on the issue of uplink power control. Attenuation level estimated from a downlink beacon is used for uplink power control. Using a highly sensitive switched radiometer with a narrowband pre- filter, we propose algorithms to estimate the downlink power based on the sampled radiometer outputs. Multipath fading and shadowing effect usually exist in a mobile satellite channel. These effects become more noticeable when an omnidirectional antenna is used by a ground receiver. In this case, noncoherent signalings like MFSK and DPSK are more practical and robust than other coherent signals. The second part of this thesis analyzes cutoff rate performance of multichannel MFSK and DPSK signals in various mobile satellite environments. System design issues like the diversity combining, the choice of binary or M- ary codes, the metric conversion and quantization losses, and the deinterleaving order are all investigated.
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