Fade countermeasure using signal degradation estimation for demand-assignment satellite systems

This paper describes a complete fade countermeasure system, designed for th in route user-oriented and fully meshed satellite networks. The signal degr adation due to the residual up-link attenuation after up-power control inte rvention, plus the down-link attenuation, is compensated for by varying the FEC coding and bit rates of the data. Down and up-link signal degradations are evaluated separately: the former by collecting statistics of quantized levels of the demodulated PSK signal, and the latter by using a narrow ban d signal level estimator. Measurement times are optimized using a model to evaluate the scintillation variance. The performance evaluation of the whol e system in the presence of additive white Gaussian noise (AWGN), shows tha t very small link power margins can be adopted.