Experimental Assessment of Optimal ACM Parameters in Q/V-band Satellite Communication

Broadband satellite communication systems, with their global access and broadcasting capabilities, are assuming an increasing relevance in the framework of modern Information Society. These systems could greatly benefit from the use of Extremely High Frequency (EHF); in particular "beyond Ka-band" frequencies can provide the advantage of large bandwidth availability but also smaller antenna size for a fixed gain, or conversely, higher antenna gain for a fixed size. One of the main drawback that limits the use of these frequencies is represented by the strong impairments caused by the lower part of the atmosphere; research activities on techniques for propagation impairments mitigation are needed, in order to dynamically adapt the system to the channel conditions; in particular Adaptive Coding and Modulation (ACM), Data Rate Adaptation (DRA), up-link power control (ULPC), spatial diversity (both using classical site diversity approach or smart gateways approach) and on-board adaptive power allocation can be efficiently adopted to improve EHF satellite systems performance. At present the use of Ka-band is the benchmark for broadband satellite communications commercial application; higher bands are under scientific investigation; in particular Italian Space Agency started an experimental campaign on Q/V band based on Alphasat "Aldo Paraboni" P/L; in this paper, the authors will report the latest results of such experiments, with a specific focus on ACM techniques optimization.