Multibeam-based mmWave segmented beamforming array system for high efficiency and secure communication

A new mmWave transmitter architecture with multibeam-based segmented beamforming arrays (SBAs) for high-efficiency and secure communication is proposed. Unlike convetional communication architecture, which transmits a high-order QAM signal through a single RF-chain, the proposed structure transmits independently controlled multiple QPSK signals to form M-QAM signals. The multiple independent SBA chains radiate independent QPSK signals at each chain’s maximum operation efficiency to reduce the peak-to-average-power ratio. Then, multiple beams with QPSK signals are steered by the SBAs to form a line of combination (LoC) where multiple QPSK signals are spatially vector-combined to generate M-QAM signals correctly. For any unidentified receiver outside the LoC, the desired high-order QAM signals cannot be retrieved owing to the lack of required sets of QPSK signals and SBA steering information. Thus, higher data security can be also guaranteed. To verify the proposed architecture, 28-GHz SBA-based transmitter and reference receiver were implemented. Three QPSK signal sets were transmitted by three SBAs supporting independent beamforming to flexibly create a narrow LoC where the receiver retrieved 64-QAM signals successfully. Furthermore, secured data transmission was verified with an extra eavesdropper in the vicinity of the target receiver. By controlling the LoC, only the target receiver successfully demodulated the 64-QAM signals.