Equalisation of satellite mobile channels with neural network techniques

The use of non-linear amplifiers near saturation in satellite channels caus es severe distortion of the transmitted signal. These distortions make the matter of power efficiency prevail over spectral efficiency in satellite co mmunication systems. Nowadays, the use of satellite segments for applicatio ns requiring ever increasing data rates puts this principle in question. Th e present article proposes to fight non-linear distortion caused by satelli te amplifiers by resorting to simple neural network equalisation devices in the receiving earth terminals. Several neural network equalisers are intro duced, and applied to a satellite Universal Mobile Telecommunication System (S-UMTS) channel model. They are shown not only to outperform conventional equalisation techniques like the linear transversal equaliser, but also to have better performance than the non-linear Volterra equaliser. The perfor mance improvement is all the more sensitive as the modulation scheme used i s severely distorted. The case of 16-QAM transmission over a mobile satelli te link is studied in details.