Analysis of the effect of nonlinear low noise amplifier with memory for wideband spectrum sensing

Abstract

In wideband sensing receivers, especially in low-cost mass-product devices, the sensing operation is usually done in a range where the RF front-end components, such as the LNAs exhibit a nonlinear behavior. Consequently, intermodulation (IMD) and crossmodulation (XM) are generated and cause distortion in the spectrum sensing region. This paper investigates the impact on the threshold level setting of a wideband energy detection based spectrum sensing caused by a nonlinear LNA at the radio frequency (RF) front-end of a wideband cognitive radio receiver. The third and fifth order terms of the expansion of the nonlinearity characteristics are modeled using a memory-polynomial model. The main contribution of this study is the derivation of a proper threshold level for different frequency bins.