Adaptive Volterra compensation for interference of two high-order modulation carriers over satellite

We introduce complete analytical characterization of the nonlinear interference that results when passing more than one high-order modulation carrier through the same nonlinear transponder HPA. Based on this analysis, a novel Volterra filter is proposed that models nonlinear intersymbol interference (ISI) and adjacent channel interference (ACI). Our focus is on adaptive algorithms so that the solutions are completely blind to unknown transponder HPA characteristics, and can rapidly respond to varying operating back-off level. Furthermore, two families of adaptive solutions are proposed to compensate for the nonlinear ISI and ACI. The effectiveness of the proposed techniques is demonstrated via extensive simulations for high-order QAM and APSK modulation schemes.