Theoretical foundations and real-time DSP implementations for secure millimeter-wave beamforming.
By leveraging radar-derived spatial coordinates, the base station constructs high-accuracy line-of-sight channel estimates without feedback overhead, calculating optimal precoding matrices that zero out eavesdropping mutual information.
Real-time precoder calculation is implemented on Xilinx UltraScale+ FPGAs using systolic Cholesky decomposition, updating directional modulation weights every 125 microseconds to counter moving eavesdroppers.
Outdoor 28 GHz testbed measurements confirmed that unauthorized receivers displaced by merely 2 degrees from the main beam experienced 100% bit error rates (BER ~ 0.5), completely preventing eavesdropping.