Analysis of Spectral Regrowth on Forward-Link CDMA Signals Based on Fifth-order Nonlinear Distortion
Ying Shi, Lin Maoliu, Yiping Chen, Li Juan · 2007
In this paper, based on the time domain model of the forward-link CDMA signal, analytical expressions relating the spectral regrowth of the CDMA signal passed through a nonlinear amplifier with a digitally modulated carrier to both the third-order intercept point and fifth-order intercept point, IP3and IP5, were derived using the power series and high-order cumulant. This statistical method considers the nonlinear transformation of statistical properties of moments of a complex Gaussian random variable to develop a simple expression for the autocorrelation of the output signal. Analytical results are useful in finding optimal operating conditions of the power amplifier. In the end, the comparison between the simulation and practical measurement show that a better fit using both IP3and IP5than using only IP3.