Contents I. Introduction
For future satellite-to-ground communications link, very high throughput might be achievable at a reasonable cost assuming the use of existing single mode components developed for fiber technologies such as erbium doped fiber amplifier (EDFA). However, atmospheric turbulence degrades the injection efficiency of the incoming wave into single mode components. This leads to signal fading and channel impairments. Several mitigation strategies are considered to prevent them. The use of adaptive-optics (AO) should contribute to reduce substantially the severity of the fading at the expense of potentially complex and expensive systems if very high injection stability is required.
