A Design Method of Cognitive Overlay Links for Satellite Communications

In this paper, we present a method to design cognitive overlay links for satellite communications, in order to allow the primary and the cognitive users to transmit concurrently while using efficiently the available power resources. By means of trellis shaping based dirty paper coding (DPC) and superposition techniques, numerous schemes are investigated in various realistic scenarios, and different trade-offs between power efficiency vs complexity are made. By simulations, we first show that we are able to design schemes where the primary user bit error rate (BER) is maintained as in the absence of the cognitive user interference. Secondly, thanks to trellis precoding and an appropriate constellation expansion, we show that the BER of the cognitive user can be made within 1dB of corresponding the Gaussian channel BER.