A RF Predistortion Approach to in-Device Coexistence between 2.4 GHz Wi-Fi and 4G LTE Signals

Abstract

This paper presents the efficiency enhancement of RF power amplifiers (PA) using a RF predistortion (PD) technique and evaluates its performance in coexistence of the 2.4 GHz Wi-Fi and 4G LTE signals. For coexistence applications of the 2.4 GHz Wi-Fi and 4G LTE systems, a bulk acoustic wave (BAW) filter is practically adopted as a Wi-Fi coexistence filter at the Wi-Fi transmitter to greatly attenuate the signal leakage from the 2.4 GHz Wi-Fi band into the 4G LTE bands for mitigating adjacent channel interference. The presented RF PD technique shows the robust performance over widely adopted digital predistortion (DPD) technique in such coexistence applications, where strictly bandlimited channels close to the band edges are applied. In practical 2.4 GHz Wi-Fi applications, we reveal the effectiveness of the RF PD on all channels and the ineffectiveness of the DPD on some channels close to the band edges for the first time in suppressing spectral regrowth in the coexistence of Wi-Fi and LTE signals.