In satellite mobile communications, TWT (Traveling Wave Tube) amplifiers are used to increase power efficiency. Unfortunately, power-efficient amplifiers cause nonlinear distortions to the transmitted signal These distortions make the received symbols no longer on the original regular lattice but on a warped one. Several authors use analytical models (such as Saleh model) to describe both amplitude (AM/AM) and phase (AM/PM) nonlinear distortions of TWT amplifiers. However there do exist some modeling error (ME) in these models (e.g. a mean squared modeling error, MSE = 10−3). Such modeling error will degrade the knowledge of the channel for the receiver, thus the receiver will become sub-optimum in the presence of modeling error. What's more, modeling error will change the decision boundaries of receiver; and therefore will decrease the detection performance.