Wireless spectrum at 60 GHz is widely used for high-resolution sensing, e.g., human activity monitoring, and is increasingly adopted for high-throughput communication using IEEE 802.11ad/ay devices. To limit the power consumption and hardware complexity of 60 GHz radios, low-resolution phase shifters are preferred. For example, a 1-bit phase shifter consumes around 10 mW , whereas a 4-bit phase shifter requires about 45 mW. Low-resolution phase shifters, however, result in radiation leakage that poses security risks such as eavesdropping and jamming, and they also hamper the sensing accuracy of 60 GHz systems. Balancing the adverse effects of low-resolution phase shifters on communication and sensing with the increased power consumption and heat generated by high-resolution counterparts remains a challenging trade-off. Specifically, we require a system that is more flexible and dynamic to the use-case and the situation. This brings us to the research question: How should phase-shifter resolutions be distributed across a 60 GHz array to maximize secrecy and sensing performance for a given deployment and power budget? Fabricating mixed resolution phased arrays is feasible, but the above research question to tailor phase shift resolutions to a deployment remains unexplored. Our radiation-leakage minimizing approach is fundamentally different from existing methods in the literature that switch off antennas at random to distribute the leaked radiation, and those that use a fixed resolution hardware. This is because our method activates all the antennas (with different phase shift resolutions), thereby being more power-efficient than existing solutions. We will deliver a 60 GHz testbed demonstrating secure beamforming using a heterogenous profile of phase shifter resolutions.
Team: Nitin Myers (TU Delft), Arash Asadi ( TU Delft), Yang Miao (UT), and Ulf Johannsen TU/e)