External Passive Intermodulation Suppression by General Linear Combination based Robust Adaptive Beamforming

Zhongrui Wang, Xu Zhu, Yufei Jiang, Haiyong Zeng, Baiqi Li

Abstract: External passive intermodulation (ePIM), which results from external passive sources around base station (BS), such as rust fence, barn roof and weather may cause different levels of intermodulation power and significant interference in the uplink. In this paper, we propose an adaptive beamforming algorithm based on the general linear combination (GLC) to suppress the ePIM signal, which is the first attempt to design beamforming for ePIM suppression. Rather than the complex and intractable modeling of the ePIM signal, the ePIM and noise correlation (PNC) matrices can be estimated and combined by the GLC to design the beamformer, which is more adaptive and can significantly suppress the ePIM. In addition, The power of the essential factors of the ePIM sources is estimated based on the eigenvalues and eigenvectors of the ePIM signal. Simulation results show that the proposed beamformer provides a near-optimal output signal-to-interference-plus-noise ratio performance and also significantly outperforms the existing beamforming schemes which merely focus on co-channel interference without considering ePIM suppression.

External IDs:dblp:conf/vtc/WangZJZL22