A Mm-Wave Transmitter MIMO with Constellation Decomposition Array (CDA) for Keyless Physically Secured High-Throughput Links
Conventional phased array beamforming realizes spatial physical security but is effective only for large arrays, while most cryptographic algorithms require security key exchanges and pose large computation overhead and latency to handle Gbit/s throughput. We propose a Constellation-Decomposition Array (CDA) MIMO technique to achieve a highly secured yet keyless wireless link for low-element count arrays. The CDA MIMO spatially combines lower order QAMS, so that the high-order QAM is observed only in the target direction and shows large distortions in other directions. Temporal swapping of the decomposed CDA constellations among MIMO elements further enhances the security. The proposed scheme is demonstrated on an 8-element 25-34GHz TX MIMO array in 45nm CMOS SOI with on-package antennas. Over-the-air 4-elememt MIMO measurements achieve an information beamwidth of 2.5˚/5˚ at up-to 3Gbit/s by forming a 64QAM signal using three QPSKs or 16QAM/QPSK, respectively, demonstrating a mm-Wave wireless link with simultaneous security and high throughput.