What's new:
- 2021-Sep-01 Released PulseAudio.js 1.2.0
- 2021-Aug-30 The paper Talking After Lights Out: An Ad Hoc Network for Electric Grid Recovery has been accepted by 2021 IEEE SmartGridComm.
- 2021-Aug-16 The paper An Analysis of Amazon Echo's Network Behavior has been accepted by 2021 IEEE GlobeCom.
- 2021-May-27 New paper An Analysis of Amazon Echo's Network Behavior
- 2021-Mar-29 Updated list of student projects
Research
My main research area is network services and protocols for cyber-physical systems, the Internet of Things (IoT), and multi-media network services. My research aims to enable self-managing IoT systems that automatically adapt to a changing environment and make automated decisions based on high-level programs and policies. I am also interested in developing programming abstractions for IoT applications that follow data, i.e., applications deployable to the network edge.
At Columbia, I supervise student projects at the undergraduate and graduate levels. I also occasionally mentor high-school students interested in computer science. Our paper on the design of a wireless networking lab won the Best Educational Paper Award at the Second GENI Educational and Research Workshop in 2013. I helped to design the homework assignments for the Advanced Programming.
Selected Publications
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2021 IEEE Global Communications Conference: IoT and Sensor Networks (Globecom2021 IoTSN). Madrid, Spain. December 2021
With over 20 million units sold since 2015, Amazon Echo, the Alexa-enabled smart speaker developed by Amazon, is probably one of the most widely deployed Internet of Things consumer devices. Despite the very large installed base, surprisingly little is known about the device's network behavior. We modify a first generation Echo device, decrypt its communication with Amazon cloud, and analyze the device pairing, Alexa Voice Service, and drop-in calling protocols. We also describe our methodology and the experimental setup. We find a minor shortcoming in the device pairing protocol and learn that drop-in calls are end-to-end encrypted and based on modern open standards. Overall, we find the Echo to be a well-designed device from the network communication perspective.
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2021 IEEE International Conference on Communications, Control, and Computing Technologies for Smart Grids (SmartGridComm) (IEEE SmartGridComm'21). Aachen, Germany. October 2021
When the electrical grid in a region suffers a major outage, e.g., after a catastrophic cyber attack, a "black start" may be required, where the grid is slowly restarted, carefully and incrementally adding generating capacity and demand. To ensure safe and effective black start, the grid control center has to be able to communicate with field personnel and with supervisory control and data acquisition (SCADA) systems. Voice and text communication are particularly critical. As part of the Defense Advanced Research Projects Agency (DARPA) Rapid Attack Detection, Isolation, and Characterization Systems (RADICS) program, we designed, tested and evaluated a self-configuring mesh network prototype called the Phoenix Secure Emergency Network (PhoenixSEN). PhoenixSEN provides a secure drop-in replacement for grid's primary communication networks during black start recovery. The network combines existing and new technologies, can work with a variety of link-layer protocols, emphasizes manageability and auto-configuration, and provides services and applications for coordination of people and devices including voice, text, and SCADA communication. We discuss the architecture of PhoenixSEN and evaluate a prototype on realistic grid infrastructure through a series of DARPA-led exercises.
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TPRC48: The 48th Research Conference on Communication, Information, and Internet Policy. February 2021
The COVID-19 pandemic and related restrictions forced many to work, learn, and socialize from home over the internet. There appears to be consensus that internet infrastructure in the developed world handled the resulting traffic surge well. In this paper, we study network measurement data collected by the Federal Communications Commission's Measuring Broadband America program before and during the pandemic in the United States (US). We analyze the data to understand the impact of lockdown orders on the performance of fixed broadband internet infrastructure across the US, and also attempt to correlate internet usage patterns with the changing behavior of users during lockdown. We found the key metrics such as change in data usage to be generally consistent with the literature. Through additional analysis, we found differences between metro and rural areas, changes in weekday, weekend, and hourly internet usage patterns, and indications of network congestion for some users.
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Proceedings of the 2nd International Workshop on Edge Systems, Analytics and Networking. New York, NY, USA. 2019
The serverless and functions as a service (FaaS) paradigms are currently trending among cloud providers and are now increasingly being applied to the network edge, and to the Internet of Things (IoT) devices. The benefits include reduced latency for communication, less network traffic and increased privacy for data processing. However, there are challenges as IoT devices have limited resources for running multiple simultaneous containerized functions, and also FaaS does not typically support long-running functions. Our implementation utilizes Docker and CRIU for checkpointing and suspending long-running blocking functions. The results show that checkpointing is slightly slower than regular Docker pause, but it saves memory and allows for more long-running functions to be run on an IoT device. Furthermore, the resulting checkpoint files are small, hence they are suitable for live migration and backing up stateful functions, therefore improving availability and reliability of the system.
Teaching
- ENGI E1006 Introduction to Computing for Engineers and Applied Scientists
Spring 2023 - COMS W3132 Intermediate Computing in Python
Spring and Summer 2024
Posters
- A Platform for Experimental Research in Critical Voice Communications, NIST PSCR 2022 Annual Stakeholder Meeting, San Diego, CA, June 2022
- Naming, Twinning, and Observing--Towards Cyber-Physical Systems Spanning Administrative and Geographical Boundaries, 2021 NSF CPS Principal Investigators' Meeting, June 2021
- Towards Scalable, Reliable, and Resilient IoT Systems for Smart Cities [video], Smart Cities Center Poster Session, Columbia University Data Science Institute, November 6, 2020
- Alexa, How Secure Are You?, Summer Research Institute Poster Session, Barnard College, August 2018
- Smartlock: Senior Design Expo Project, Senior Design Expo, Columbia University, May 2015
Talks
- A Platform for Experimental Research in Critical Voice Communications [video], NIST PSCR 2022 Annual Stakeholder Meeting, San Diego, CA, June 2022
- An Analysis of Amazon Echo's Network Behavior [video], IEEE GLOBECOM, Madrid, Spain, December 2021
- Talking After Lights Out: An Ad Hoc Network for Electric Grid Recovery, IEEE SmartGridComm21, Aachen, Germany, October 2021
- Naming, Twinning, and Observing--Towards Cyber-Physical Systems Spanning Administrative and Geographical Boundaries [video], 2021 NSF CPS Principal Investigators' Meeting, June 2021
- Social Distancing and the Internet: What Can Performance Measurements Tell Us?, TPRC 48, Washington, D.C., February 2021
- Prototyping Distributed IoT Applications With WebRTC, IPTComm 2016, Chicago, October 2016
- Access Control for Smart Objects, IAB Workshop on Smart Object Security, Paris, March 2012
- SIP Express Router, FOSDEM, Brussels, February 2006
Software
- lora-modem-abz: Open LoRaWAN firmware for Murata Type ABZ wireless module [Python library]
- py-mjpeg: Python library for working with MJPEG streams
- AMBE: A library for working with DVSI's vocoder chips
- PulseAudio.js: PulseAudio client for NodeJS
- mcv-testbed: Testbed for experiments with mission-critical voice
- autoprov: Auto-provisioning server for Yealink W52P phones
- dns2avahi: A DNS to Avahi (multicast DNS) gateway