Use of space-time channel models and data for design and control of adaptive SatCom systems

Propagation Impairments Mitigation Techniques (PIMTs) are necessary for satellite-based systems (typically operating at frequencies above 20 GHz) intended to provide large bandwidth to the end users. This contribution presents the best performing space-time channel model to be used in the design and control of adaptive SatCom systems. First, models able to predict the spatial distribution of the rain intensity over large (continental) areas are presented and their performance assessed against extensive radar databases. Space rain field generators are also shown to be of key importance for the control of an on-board power allocation system of a satellite equipped with a reconfigurable antenna. Finally, this contribution presents the performance of two space-time rain field generators in estimating the throughput of a simplified geometry of an Interactive MultiMedia Broadband Service (IMMBS) system implementing ACM.

I. INTRODUCTION

The use of very high carrier frequencies for MultiMedia and Broadcasting SatCom systems is nowadays mandatory because of the congestion of the lower frequency bands, but even more because of the increasing request of larger bandwidth from the end users. The evolution is therefore towards the use of the Ka band (20–30 GHz) within few years and of the Q/V band (40–50 GHz) in the future. The design of satellite-based systems at frequencies above 20 GHz requires counteracting very high atmospheric fades in order to meet the requested availability and quality criteria. This cannot be faced with the classical approach of a fixed margin because it would lead to unrealistic over-dimensioning of the ground terminals front-ends and of the on-board power level. It is therefore necessary to implement specific Propagation Impairments Mitigation Techniques (PIMT). Two types of PIMT can be considered: either those which take into account the spatial and temporal de-correlation of atmospheric attenuation caused by meteorological phenomena [1] [2], or those based on the dynamic selection of the transmission modulation/coding pair (ACM) [3] and/or on the Data Rate Control strategy (DRA).