Co-channel interference mitigation using satellite based receivers

Abstract

This thesis investigates a means to mitigate co-channel interference from fourth generation cellular signals in order to support passive synthetic aperture radar (SAR) imaging using those same signals. Synthetic aperture radar is a staple of the military and intelligence communities, but the active transmission required for such images informs the target of the imaging process. Use of passive signals, such as the orthogonal frequency-division multiplexing (OFDM) signals of fourth generation cellular systems, is an attractive option, but co-channel interference mitigation is required. A method to separate the transmitted signals that leverages the estimated signal delays between multiple transmitters and receivers is examined for narrowband and wideband signals. Multiple methods of assessing recovery performance are proposed. The impact of noise is considered, as is the impact of collection geometry on recovery perfor-mance, and recovery of OFDM signals is evaluated. Signal interpolation is a critical element of the proposed recovery process, and two methods are compared for accuracy and speed of computation.