Signal quality monitoring to counter rain fading with adaptive information bit energy in satellite thin route TDMA systems

This paper describes a complete fade counter measure system, based on up-link transmission power control, plus data coding and bit rates variation. The system is designed for thin route TDMA user-oriented satellite networks, used for LAN interconnection. A multicarrier access to the satellite transponder is envisaged to exploit the entire transponder bandwidth with limited data rates of each carrier. The modest performance required by the earth stations means that the antennas can easily be installed on the user's premises. In order to avoid excessive intermodulation noise, the satellite transponder in put back-off must be constant and sufficient to in operate in the linear zone. This imposes a calibrated action of the up--link power control, which is possible only by knowing the up-link attenuation with good accuracy. The total signal degradation, due to the residual up--link attenuation after up--power control intervention, and to the down-link attenuation,is compensated for by varying the coding and bit rates of the data signal to noise estimator, based on the statistics of quantised levels of the demodulated PSK signal and a narrow band signal level estimator are employed to apply the countermeasures that are able to maintain the data bit error rate required by the user