I have pursued research on mobile computing and time-sensitive systems in the past. I have listed some of the related projects below.
Mobile Computing Applications
Mobile devices have enjoyed tremendous growth in recent years and this trend is expected to continue. Many of these mobile devices have some form of wireless communication ability, whether long range, such as cellular, or short range such as WiFi or Bluetooth, or both. My projects in this area have focused on using these communication devices to provide functionality not available in desktop environments. I pursued this work in collaboration with Prof. Eyal de Lara.
In this project, we explored the idea of building a network based only on pair-wise contact between users. By using user mobility as a network transport mechanism, communication capability can be provided where there is no established network infrastructure, or it can be used to extend the reach of established infrastructure.
To collect user mobility data, we ran two user studies by giving instrumented PDA devices to groups of students to carry for several weeks. Our empirical data suggested that it is possible to make reasonable routing decisions based only on pair-wise contact, without previous knowledge of the mobility model or location information.
Why use USB keys, You have Wireless!
Consider two individuals sitting at a conference where there is no wireless access. If the two individuals wanted to share an email, they would not be able to do so because existing email applications are hard-coded to communicate with mail servers via the Internet.
In this project, we investigated a new networking framework that enables applications to operate seamlessly in infrastructure as well as ad hoc modes. Haggle allows incorporating several protocols in routing, redirection, and naming, and it provides users the ability to take resource limitations such as power and cost into consideration. This project was conducted as part of the Haggle project with Intel Research, Cambridge, UK.
Using Radio Context for Sharing and Filtering Information
Mobile devices are increasingly being used to access the Internet, and to generate user-driven content such as digital photographs, blogs, etc. As the amount of such content continues to grow, users will need effective methods for sharing, finding and filtering "useful" content, especially in mobile and social settings. This problem is challenging because the user interfaces on mobile devices are typically small and difficult to use which makes it cumbersome to utilize standard sharing and searching modalities that work well on desktop systems.
In this project, we worked on a system called Copernicus that allowed using the multiple radios on a mobile device to establish a sense of environmental context (e.g., location, time, etc.) to enable sharing and filtering of user-generated content.
I worked on improving the timeliness of general-purpose operating systems during my PhD.
Time-Sensitive Linux (TSL)
In this project, I explored various operating systems techniques needed to support time-sensitive applications that require low-latency response from the kernel and from other system-level services. These techniques are implemented in the Time-Sensitive Linux (TSL) system.
I designed and developed a feedback-based CPU scheduler for adaptive multimedia as well as for soft real-time applications. The real-rate scheduler in implemented in the Linux kernel over a proportion-period scheduler. The scheduler supports automatic assignment of allocations to processes based on application-specific progress information such as fill levels of buffers in a pipelined application.
TCPivo is a tool that provides high-speed packet replay from a trace file using standard PC hardware and freely available open-source software. It uses Time-Sensitive Linux for precision timing.
Quasar Video Pipeline
As part of the Quasar project, I helped develop a prototype adaptive media streaming system. The streaming system supports dynamic mapping of user-level quality adaptation policies to priority assignments on data and adaptive real-time streaming over best-effort networks. This work is continuing as part of the Qstream projects.
I developed a software oscilloscope tool called Gscope for visualization of time-sensitive applications. It was used extensively at OGI for applications such as the real-rate scheduler, Quasar video pipeline, Mxtraf network traffic generator. This tool is released as open source. Latest release.