The Channel Capacity of MIMO Satellite Links in a Fading Environment: A Probabilistic Analysis

The impact of atmospheric impairments on the bandwidth efficiency of Multiple-Input Multiple-Output (MIMO) geostationary satellite links is investigated theoretically. In particular we analyze the impairments caused by precipitation because especially rain and wet snow are the most severe atmospheric impact factors degrading the channel capacity. We focus on Line-of-Sight (LOS) MIMO links that are shaped for optimum channel capacity. For that purpose the link optimization suggested in [1] is applied. Our investigations reveal to which extent the MIMO satellite channel capacity is affected by atmospheric signal attenuation and signal phase disturbances, which might reduce the number and strength of spatial subchannels (eigenmodes). Especially the impact of signal attenuation is investigated by means of probabilistic analyses, quantifying the amount and percentage of time which the link capacity degradation exceeds a particular value. Altogether we conclude that, although a loss of capacity cannot be avoided in general, MIMO systems outperform Single-Input Single-Output (SISO) designs by far, not only in terms of bandwidth efficiency but also in link reliability.