David T. Nguyen

Meta

Wearable glasses are on the rising edge of development with great user popularity. However, user data stored on these devices bring privacy risks to the owner. To better protect the owner’s privacy, a continuous authentication system is needed. In this paper, we propose a continuous and noninvasive authentication system for wearable glasses, named...

Mobile video chat apps offer users an approachable way to communicate with others. As high-speed 4G networks are being deployed worldwide, the number of mobile video chat app users increases. However, video chatting on mobile devices brings users financial concerns, since streaming video demands high bandwidth and can use up a large amount of data...

We live in a 3-D world. However, the smart phones that we use every day are incapable of sensing depth, without the use of custom hardware. By creating new depth sensors, we can provide developers with the tools that they need to create immersive mobile applications that take advantage of the 3-D nature of our world. In this paper, we propose a new...

WiFi effectively has two extremes: low power consumption and high latency, or low latency and high power consumption. WiFi Power Save Mode saves energy by trading added latency for less power consumption. Minimal latency but maximum power, on the other hand, is consumed with WiFi Active Mode. While research has advanced in mitigating these extremes...

The smartphone has become an important part of our daily lives. However, the user experience is still far from being optimal. In particular, despite the rapid hardware upgrades, current smartphones often suffer various unpredictable delays during operation, e.g., when launching an app, leading to poor user experience. In this paper, we investigate...

Video chat apps enable users to stay in touch with their family, friends and colleagues. However, they consume a lot of bandwidth and hence can quickly use up a monthly data plan quota, which is a high-cost resource on smartphones. In this paper, we propose LBVC (Low-bandwidth Video Chat), a user-guided vibration-aware frame rate adaption framework...

Existing research has demonstrated that inter-body sensor network (inter-BSN) information sharing among coexisting BSNs can enhance applications' performance and save energy. However, how to achieve effective inter-BSN information sharing through wireless communication is a challenging task. On one hand, a BSN should be able to discover neighboring...

Wireless sensor network applications, such as those for natural disaster warning, vehicular traffic monitoring, and surveillance, have stringent accuracy requirements for detecting or classifying events and demand long system lifetimes. Through quantitative study, we show that existing event detection approaches are challenged to explore the sensin...

Continuous authentication modalities allow a device to authenticate users transparently without interrupting them or requiring their attention. This is especially important on smartphones, which are more prone to be lost or stolen than regular computers, and carry plenty of sensitive information. There is a multitude of signals that can be harnesse...

Smartphones suffer various unpredictable delays, e.g., when launching an application. In this work, we investigate the behavior of reads and writes in smartphones. We conduct the first large-scale measurement study on the Android I/O delay using the data collected from our Android application running on 1480 devices within 188 days. Among others, w...

The time it takes to launch a smartphone application is unpredictable. In this paper, we explore how these unpredictable launch times are affiected by constraints associated with reading (writing) from (to) ash storage. We conduct the first large-scale measurement study on the Android I/O delay using the data collected from our Android application...

Despite the rapid hardware upgrades, current smartphones suffer various unpredictable delays during operation, e.g., when launching an app, leading to poor user experience. In this work, we investigate the behavior of reads and writes in smartphones. We conduct the first large-scale measurement study on the I/O delay of Android using the data colle...

The smartphone has become an important part of our daily lives. However, the user experience is still far from being optimal. In particular, despite the rapid hardware upgrades, current smartphones often suffer various unpredictable delays during operation, e.g., when launching an application, leading to poor user experience. This video features ou...

In this paper, to our best knowledge, we are first to provide an experimental study on how storage techniques affect power levels in smartphones and introduce energy-efficient approaches to reduce energy consumption. We evaluate power degradation at several layers of block I/O, focusing on the block layer and device driver. At each level, we invest...

We present an experimental study of how storage techniques impact energy consumption in smartphones. We design and implement a system that tracks I/O activities of smartphones in real-time and dynamically changes storage configuration by matching I/O patterns in order to reduce energy consumption. Our system is evaluated on the 20 most popular appl...

As mobile video traffic is becoming dominant, balancing the mobile video quality and bandwidth usage is a relevant but hard problem. Particularly, in this project, we attempt to reduce the bandwidth usage of video chats through frame rate adaption. The key idea of this project is to save bandwidth through reducing frame rate at the sender and inter...