Polarized Beamforming for Enhanced Countermeasure Against Interference in Wireless Systems
Wireless communications are a revolution in the information era but they are vulnerable to jamming and interference in general from other wireless signals. Beamforming is a promising technique to counteract the impact of jamming attacks. However, when the direction of the desired signal is close to that of the jamming signal, the performance of the traditional anti-jamming beamformer is significantly degraded due to the indistinguishable signals and interferences in space domain. Polarized beamforming has been proposed to solve this problem by filtering interference from the desired signal in both space and polarization domain. However, existing work only considered far-field radiation region of the signal by assuming that the transmitter and the receiver are far apart while near-field wireless communications have been employed in more and more applications. In this dissertation, an enhanced countermeasure method for mitigating jamming attacks in the near-field and far-field radiation regions has been proposed by using the polarized beamforming with planar arrays. The analytical expressions of the steering vectors is derived for near-field propagation. The steering vectors for far-field is shown to be an approximation of that of near-field. The beamformer is designed by using the Linearly Constrained Minimum Variance (LCMV) criterion. Simulations are conducted for beam pattern and Bit Error Rate (BER) to show a significant performance improvement of the proposed anti-jamming system even when the desired signals and interferences are coming from the same direction.
"Polarized Beamforming for Enhanced Countermeasure Against Interference in Wireless Systems"
ETD Collection for Tennessee State University.