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Modern mmWave systems have limited scalability due to inflexibility in performing frequency multiplexing. All the frequency components in the signal are beamformed to one direction via pencil beams and cannot be streamed to other user directions. We present a new flexible mmWave system called mmFlexible, which enables flexible directional frequency multiplexing. In this system, different frequency components of the mmWave signal are beamformed in multiple arbitrary directions with the same pencil beam. Our system makes two key contributions: (1) We propose a novel mmWave front-end architecture, called a delay-phased array, that utilizes a variable delay and variable phase element to create the desired frequency-direction response. (2) We propose a novel algorithm called FSDA (Frequency-space to delay-antenna) to estimate delay and phase values for the real-time operation of the delay-phased array. Through evaluations using mmWave channel traces, we demonstrate that mmFlexible achieves a 60-150% reduction in worst-case latency compared to the baselines.
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SpiroMilli: Bringing Ad-hoc Spirometry to 5G Devices
The rapid evolution of the telehealth industry, accelerated recently by stay-at-home directives, has created a demand for more ubiquitous health-sensing tools. One such tool is the Spirometer. Spirometers have been used in traditional clinics to measure lung capacity (volume) as well as airflow (flow rate) and have wide applicability in the diagnosis of Asthma, COPD, and other pulmonary diseases. In addition, they can be used to diagnose Dyspnea, i.e., shortness of breath, one of the symptoms of the COVID-19 virus. Several spirometers are available commercially for home-use, but they are either costly, cumbersome or provide limited flow information. We propose SpiroMilli, a low-barrier means to performing spirometry at home using the millimeter-wave (mmWave) technology in 5G-and-beyond devices. To perform a test, users will hold the device in front of their mouth, fully inhale, then sharply exhale. The system will then output seven key indicators, e.g., Forced Vital Capacity (FVC), Peak Expiratory Flow (PEF), etc., along with a flow-volume curve. SpiroMilli’s key idea is intuitive: Strong airflow in front of the mmWave antenna creates tiny vibrations, and these vibrations affect the phase of reflected signals from nearby objects. For example, a 79 GHz device (wavelength: 3.79 mm) will register a 5 µm displacement as a 1◦ phase change.
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- Award ID(s):
- 1910853
- PAR ID:
- 10296783
- Date Published:
- Journal Name:
- Proceedings of the 22nd International Workshop on Mobile Computing Systems and Applications
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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