Sangtae Ha

Sangtae Ha

I am an Assistant Professor in the Computer Science Department at the University of Colorado Boulder. My research focuses on building and deploying practical systems that span multiple disciplines including networks and distributed systems, internet protocols and algorithms, and wireless (LTE) networks and security. I run the Internet Systems Lab (ISL).

Email: sangtae DOT ha AT colorado DOT edu

ECCR 1B14
1045 Regent Drive 430 UCB
Boulder CO, 80309-0430 USA



Sangtae Ha is an Assistant Professor in the Computer Science Department at the University of Colorado Boulder. He was an Associate Research Scholar in the Department of Electrical Engineering at Princeton University from 2009 to 2013. He received his Ph.D from the Department of Computer Science at North Carolina State University in late 2009.

His research focuses on building and deploying practical systems that span multiple disciplines, including networks and distributed systems, internet protocols and algorithms, video streaming, storage systems, wireless (LTE) networks and security, and smart data pricing. He co-founded DataMi, a startup on wireless networks, in 2012, and served as the founding CTO/VP Engineering. He also co-founded Zoomi, which develops an artificial intelligence (AI) learning platform. He serves as the technical advisor for Myota, a storage startup spun off from his recent research in secure and reliable storage. Previously, he co-authored CUBIC (RFC 8312), which is the default TCP congestion control algorithm for Linux, Android and Windows, and is currently being used by the majority of Internet servers around the world and by several billion Android and Linux devices.
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Selected Publications:

  1. Title

    Gyuhong Lee, Jihoon Lee, Jinsung Lee, Youngbin Im, Max Hollingsworth, Eric Wustrow, Dirk Grunwald and Sangtae Ha,
    ACM MobiSys 2019 (40 out of 172 = 23.2% acceptance rate).

  2. CASTLE over the Air: Distributed Scheduling for Cellular Data Transmissions

    Jihoon Lee, Jinsung Lee, Youngbin Im, Sandesh Sathyanarayana, Parisa Rahimzadeh, Xiaoxi Zhang, Max Hollingworth, Carlee Joe-Wong, Dirk Grunwald and Sangtae Ha,
    ACM MobiSys 2019 (40 out of 172 = 23.2% acceptance rate).

  3. I Sent It: Where Does Slow Data Go to Wait?

    Youngbin Im, Parisa Rahimzadeh, Brett Shouse, Shinik Park, Carlee Joe-Wong, Kyunghan Lee and Sangtae Ha,
    EuroSys 2019 (45 out of 207 = 21.7% acceptance rate).

  4. ExLL: An Extremely Low-Latency Congestion Control for Mobile Cellular Networks

    Shinik Park, Jinsung Lee, Junseon Kim, Jihoon Lee, Sangtae Ha and Kyunghan Lee,
    ACM CoNEXT 2018 (32 out of 185 = 17.3% acceptance rate).

  5. Virtual Redundancy for Active-Standby Cloud Applications

    Gueyoung Jung, Parisa Rahimzadeh, Zhang Liu, Sangtae Ha, Kaustubh Joshi, and Matti Hiltunen,
    IEEE INFOCOM 2018 (309 out of 1606 = 19.2% acceptance rate).

  6. Calibrating Time-variant, Device-specific Phase Noise for COTS WiFi Devices,

    Jincao Zhu, Youngbin Im, Shivakant Mishra, and Sangtae Ha,
    ACM Sensys 2017 (17.4% acceptance rate).

  7. FLARE: Coordinated Rate Adaptation for HTTP Adaptive Streaming in Cellular Networks,

    Y. Im, J. Lee, J. Han, Y. Kwon, C. Joe-Wong, T. Kwon and S. Ha,
    IEEE ICDCS 2017 (90 out of 531 = 16.94% acceptance rate).

  8. SVC-TChain: Incentivizing Good Behavior in Layered P2P Video Streaming,

    P. Rahimzadeh, C. Joe-Wong, K. Shin, Y. Im, J. Lee and S. Ha,
    IEEE INFOCOM 2017 (292 out of 1395 = 20.93% acceptance rate).

  9. Performance Analysis of Incentive Mechanism for Cooperative Computing

    C. Joe-Wong, Y. Im, K. Shin, and S. Ha,
    IEEE ICDCS 2016 (68 out of 386 = 17.6% acceptance rate).

  10. Viability of Virtual Cloud Providers

    L. Zheng, C. Joe-Wong, C. Brinton, C. Tan, S. Ha, and M. Chiang,
    ACM SIGMETRICS 2016 (28 out 208 = 13.46% acceptance rate).

  11. T-Chain: General Incentive Scheme for Cooperative Computing

    K. Shin, C. Joe-Wong, S. Ha, Y. Yi, I. Rhee and D. Reeves,
    IEEE ICDCS 2015 (70 out of 543 = 12.89% acceptance rate).

  12. Secondary Markets for Mobile Data: Feasibility and Benefits of Traded Data Plans

    L. Zheng, C. Joe-Wong, C. W. Tan, S. Ha, and M. Chiang,
    IEEE INFOCOM 2015 (316 out of 1640 = 19% acceptance rate).

  13. CYRUS: Towards Client-Defined Cloud Storage

    J. Chung, C. Joe-Wong, S. Ha, J. Hong and M. Chiang,
    EuroSys 2015 (32 out of 150 = 21.33% acceptance rate).

  14. Sponsoring Mobile Data: An Economic Analysis of the Impact on Users and Content Providers

    C. Joe-Wong, S. Ha, and M. Chiang,
    IEEE INFOCOM 2015 (316 out of 1640 = 19% acceptance rate).

  15. When the Pricing is Right: Enabling Time-Dependent Pricing for Broadband Networks

    S. Sen, C. Joe-Wong, S. Ha, J. Bawa and M. Chiang,
    ACM SIGCHI 2013

  16. Offering Supplementary Wireless Technologies: Adoption Behavior and Offloading Benefits

    C. Joe-Wong, S. Sen and S. Ha,
    IEEE INFOCOM 2013, Turin, Italy

  17. AMUSE: Empowering Users for Cost-Aware Offloading with Throughput-Delay Tradeoffs

    Y. Im, C. Joe-Wong, S. Ha, S. Sen, T. Kwon and M. Chiang,
    IEEE INFOCOM 2013 (mini-conference), Turin, Italy

  18. TUBE: Time-Dependent Pricing for Mobile Data

    S. Ha, S. Sen, C. Joe-Wong, Y. Im and M. Chiang,
    ACM SIGCOMM 2012

  19. Joint VM Placement and Routing for Data Center Traffic Engineering

    J. Jiang, T. Lan, S. Ha, M. Chen and M. Chiang,
    IEEE INFOCOM 2012 (mini conference), Orlando, Florida, 2012

  20. Time-Dependent Broadband Pricing: Feasibility and Benefits

    C. Joe-Wong, S. Ha and M. Chiang,
    IEEE ICDCS 2011.

  21. DiffQ: Differential Backlog Congestion Control for Multi-hop Wireless Networks

    A. Warrier, S. Janakiraman, S. Ha and I. Rhee,
    IEEE INFOCOM 2009.

  22. CUBIC: A New TCP-Friendly High-Speed TCP Variant

    S. Ha, I. Rhee and L. Xu,
    ACM SIGOPS Operating System Review 2008.

  23. Stochastic Ordering for Internet Congestion Control and its Applications

    H. Cai, D. Eun, S. Ha, I. Rhee and L. Xu,
    IEEE INFOCOM 2007.

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Visit the publication of the ISL for a more complete list.

2018 Fall
  1. CSCI 4273/5273: Network Systems
  2. TLEN 5330: Data Communicaitons 1

2017 Fall
  1. CSCI 4273/5273: Network Systems
  2. TLEN 5330: Data Communicaitons 1
2016 Fall
  1. CSCI 4273/5273: Network Systems
  2. TLEN 5330: Data Communicaitons 1
2016 Spring
  1. CSCI 7000-010: Advanced Internet Protocols
2015 Fall
  1. CSCI 4273/5273: Network Systems
  2. TLEN 5330: Data Communicaitons 1
2014 Fall
  1. TLEN 5330: Data Communicaitons 1

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PhD Students
  1. Zhang Liu
  2. Parisa Rahimzadeh
  3. Ibrahim Ayad
  4. Siqi Chen
  5. Prasanth Prahladan
  6. Insoo Lee
  7. Jaeyoung Oh
  8. Hyoyoung Lim
MS Students
  1. Gyuhong Lee
  2. Sandesh Dhawaskar
Researchers
  1. Dr. Jihoon Lee, Research Associate.
  2. Dr. Youngbin Im, Postdoctoral Research Associate.
  3. Dr. Jinsung Lee, Postdoctoral Research Associate.
Alumni
  1. Visiting Scholar, Ruediger Rill, now Engineering Manager at Google.
  2. Visiting Student, Dr. Trung Hieu Nguyen, now Big Data Engineer, Finland
  3. Visiting Scholar, Dr. Seung Eun Hong, ETRI.
  4. Visiting Scholar, Prof. Kyuyong Shin, Korea Military Academy.

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Visit the ISL people page for a more complete list.


Professional Services:

  • PC Co-Chair
    1. Fog World Congress, 2017.
    2. Asia-US Forum on Fog Networking for 5G and IoT, 2015.

  • General Co-Chair
    1. IEEE INFOCOM Smart Data Pricing Workshop 2017, 2016, 2013.
    2. IEEE SECON Workshop on Fog Networking for 5G and IoT 2015.
  • Guest Editor
    1. IEEE Communications Magazine Feature Topic on Fog Computing and Networking, Sept 2016.
    2. IEEE Network Magazine Special Issue on Smart Data Pricing, Aug 2015.
  • Co-Editor
    1. Smart Data Pricing, John Wiley & Sons, 2014.
  • Editorial Board
    1. Associate Editor, IEEE Internet of Things Journal, 2013 – Current.
    2. IEEE ComSoc Technology News (CTN), 2012 – 2014.
  • Program Committee
    1. IEEE INFOCOM 2019, 2018, 2017, 2016.
    2. IEEE ICDCS 2017.
    3. IEEE INFOCOM Smart Data Pricing Workshop 2015, 2014.
    4. IEEE GLOBECOM 2016, 2014, 2013.
    5. International Teletraffic Congress (ITC) 2016.
    6. IEEE SECON 2015.
    7. MobileSoft ACM Student Research Competition 2015.
    8. IEEE PIMRC 2014, 2013.
    9. WiOPT 2014, 2013, 2012, 2011.
    10. IEEE VTC 2014.
    11. IEEE IPCCC 2014, 2012.
    12. The International Workshop on Smart Complex Engineered Networks (SECNE) 2014.
    13. IEEE Workshop on Green Multimedia 2013.
    14. IEEE NAS 2012.
    15. PFLDNeT 2010.
  • Organization Committee
    1. IEEE DSN 2017.
  • Services
    1. NSF NeTS Small and Medium Panel 2017, 2016, 2015.
    2. Co-Chair, Software Infrastructure Working Group, OpenFog Consortium, 2016-2018.
    3. Publicity Co-Chair, ACM SEC 2017.
    4. CISS Session Chair 2012, 2010.
    5. Panel List, Smart Data Pricing Forum, Princeton, July 2012.
    6. Judge, Princeton Undergraduate Research Symposium, Princeton, May 2011.

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Campus Services:

  • Computer Science
    1. Computing Co-Chair, Fall 2016 – Current.
    2. Faculty Search Committee, Fall 2016 – Spring 2017.
    3. Graduate Committee, Fall 2014 – Spring 2016.

  • Interdisciplinary Telecom Program
    1. Ph.D. Committee, Fall 2014 – Current.
  • University Service
    1. Cloud Working Group, Fall 2016 – Current.
    2. Faculty Student Mentorship Program (FSMP), Fall 2014.

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We appreciate the funding from the following organizations.

Current Sponsors
  1. National Science Foundation (NSF)
  2. National Institute of Standards and Technology (NIST)
  3. DARPA
  4. Cisco Systems
  5. AT&T Research/Labs
  6. ETRI
  7. UNIST and IITP

Previous Sponsors
  1. Samsung Electronics
  2. ETRI

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