Princeton University

Sangtae Ha    Associate Research Scholar    Associate Director, the Princeton EDGE Lab    Department of Electrical Engineering    Princeton University    Office: C319E, Engineering Quadrangle,    Olden Street, Princeton, NJ 08544    Email: sangtaeh AT princeton DOT edu

Research Highlights

I am with Princeton University as an Associate Research Scholar, working with Prof. Mung Chiang, and co-founded the Princeton EDGE Lab in 2009, as the lab's first Associate Director. The EDGE Lab had its first EDGE Lab Open House on April 28, 2011, and also hosted the first Smart Data Pricing (SDP) Forum at Princeton University in July 2012. I lead the DataMi project team, which develops SDP solutions to help Internet Service Providers (ISPs) meet the increasingly untenable demand for mobile data. DataMi's consumer facing app, the DataWiz app on iOS, has been downloaded more than 130,000 in its first few months of release. I also lead a project team creating a non-profit, next generation online learning platform, called 3ND (3 Nights and Done). 3ND aims to improve very low course completion rates (less than 3%), popularly observed in popular MOOCs, through introducing short, self-contained course units (we call "3nighter") and giving regular incentives to maintain students' interest and momentum. Each 3nighter can be completed in 3 hours over a few days, providing students with a sense of urgency and a feasible path to learn on their own time without sticking to a university course calendar.

Before coming to Princeton, I was part of TCP research team, invening a new TCP congstion control protocol CUBIC, and was the primary engineer pushing it into Linux kernel 2.6.18 in 2006. Since 2006, CUBIC has been the default TCP algorithm for Linux and are currently being used by more than 40% of Internet servers around the world and by several hundres million Android/Linux users for daily Internet communication. Recent measurement study shows BIC/CUBIC ranks top with 44.51% website using it, followed by Windows' CTCP with 10 to 19% (See Lisong's recent work). The latest CUBIC implementation in the Linux kernel is available at LXR and you can see the corresponding internet draft, paper, experimental results and recent improvement. I am still maintaining and improving the code. My research focus has been on designing, evaluating and improving the performance of CUBIC, and this work was part of my Ph.D. dissertation at NCSU, advised by Prof. Injong Rhee.

Education and Professional Experience

Associate Research Scholar, Electrical Engineering, Princeton University, 2011 -

Post-doctoral Research Associate, Electrical Engineering, Princeton University, 2010

Ph.D., Computer Science, North Carolina State University, Raleigh, NC. 2009

Awards

Princeton IP Accelerator Fund Winner ($100K), DataMi Team, with Mung Chiang, Soumya Sen, Carlee Joe-Wong. NJ News

"TUBE-ing over Digital Divide", Vodafone Wireless Innovations Project 2011 Finalist, San Francisco, CA, with Mung Chiang, Soumya Sen, Carlee Joe-Wong. HTML

Outstanding Teaching Assistant Award, 38th Annual Teaching Assistant Awards 2007. HTML

Publications (Google Scholar)

2013

S. Sen, C. Joe-Wong, S. Ha and M. Chiang A Survey of Broadband Data Pricing: Past Proposals, Current Plans, and Future Trends, accepted in ACM Computing Surveys 2013

S. Sen, C. Joe-Wong, S. Ha, J. Bawa and M. Chiang When the Pricing is Right: Enabling Time-Dependent Pricing for Broadband Networks, accepted in ACM SIGCHI 2013

C. Joe-Wong, S. Sen and S. Ha, Offering Supplementary Wireless Technologies: Adoption Behavior and Offloading Benefits, accepted in IEEE INFOCOM 2013, Turin, Italy

Y. Im, C. Joe-Wong, S. Ha, S. Sen, T. Kwon and M. Chiang, AMUSE: Empowering Users for Cost-Aware Offloading with Throughput-Delay Tradeoffs, accepted in IEEE INFOCOM 2013 (mini-conference), Turin, Italy

M. Sheng, C. Joe-Wong, S. Ha, F. Wong and S. Sen, Smart Data Pricing: Lessons from Trial Planning, accepted in IEEE INFOCOM Workshop 2013 - Smart Data Pricing (in conjunction with IEEE INFOCOM 2013), Turin, Italy

2012

S. Sen, C. Joe-Wong and S. Ha, The Economics of Shared Data Plans, accepted to Workshop on Information Technologies and Systems (WITS) 2012

S. Sen, C. Joe-Wong, S. Ha and M. Chiang, Incentivizing Time-Shifting of Data: A Survey of Time-Dependent Pricing for Internet Access, accepted to IEEE Communications Magazine, 2012

S. Ha, S. Sen, C. Joe-Wong, Y. Im and M. Chiang, TUBE: Time-Dependent Pricing for Mobile Data, ACM SIGCOMM, Helsinki,2012 PDF

I. Kamitsos, P. Tsiaflakis, K. Kerpez, S.Ha and M. Chiang, Energy Efficient DSL via Heterogeneous Sleeping States: Optimization Structures and Operational Guidelines, IEEE Globecom, 2012

C. Joe-Wong, S. Sen, S. Ha and M. Chiang, Optimized Day-Ahead Pricing for the Smart-Grid with Device-Specific Scheduling Flexibility, IEEE Journal on Selected Areas in Communications, JSAC Smart Grid Series, July 2012

S. Ha, S. Sen, C. Joe-Wong, R. Rill and M. Chiang, Demo: A System for Time-Dependent Pricing , MobiSys demo, Low Wood Bay, UK, 2012. Video

H. Kim, S. Ha, M. Chiang, D. Kang and J. Kim, Iterative Resource Pooling for Bandwidth Allocation in TDM-PON: Algorithm, Convergence and Experimental Evaluation, Photonic Network Communications, Feb. 2012.

S. Sen, C. Joe-Wong, S. Ha and M. Chiang, Pricing Data: A Look at Past Proposals, Current Plans, and Future Trends, submitted to ACM Computing Surveys, Jan 2012

S. Ha, C. Joe-Wong, S. Sen and M. Chiang, Pricing by Timing: Innovation Broadband Data Plans, SPIE OPTO Broadband Access Communication Technologies VI Conference, Paper 8282-12, San Francisco, Jan, 2012

J. Jiang, T. Lan, S. Ha, M. Chen and M. Chiang, Joint VM Placement and Routing for Data Center Traffic Engineering, IEEE INFOCOM mini conference, Orlando, Florida, 2012

S. Ha, S. Sen, C. Joe-Wong, J. Mifkovich, R. Rill, Y. Im, D. Butnariu, J. Bawa and Mung Chiang, Demo: Pricing by Timing of Mobile Data , IEEE INFOCOM demo, Orlando, Florida, 2012.

I. Kamitsos, L. Andrew, H. Kim, S. Ha and M. Chiang, Better Energy-Delay Tradeoff via Server Resource Pooling , ICNC 2012 (Invited).

2011

I. Kamitsos, P. Tsiaflakis, S. Ha and M. Chiang, Energy Efficient DSL Broadband Access via Stable Sleep Mode Optimization , under submission.

C. Joe-Wong, S. Ha, S. Sen and M. Chiang, Pricing Broadband by Timing: From Optimization to Implementation , under submission.

I. Kamitsos, P. Tsiaflakis, S. Ha and M. Chiang, Stable Sleeping in DSL Broadband Access: Feasibility and Tradeoffs , IEEE Globecom 2011.

Y. Wang, I. Rhee and S. Ha, Augment SCTP Multi-Streaming with Pluggable Scheduling , IEEE INFOCOM Workshops (GI 2011), Shanghai, China

C. Joe-Wong, S. Ha and M. Chiang, Time-Dependent Internet Pricing , ITA 2011.

C. Joe-Wong, S. Ha and M. Chiang, Time-Dependent Broadband Pricing: Feasibility and Benefits, ICDCS 2011.

S. Ha and I. Rhee, Taming the Elephants: New TCP Slow Start, Computer Networks: The International Journal of Computer and Telecommunications Networking, 2011. Technical Report Errata Patch. Recent results.

2010

M. Chiang, P. Hande, H. Kim, S. Ha and R. Calderbank, Pricing Broadband: Survey and Open Problems, ICUFN 2010 (invited).

S. Ha, N. Dukkipati, V. Subramanian, F. Bonomi and I. Rhee, BLAST: A practical loss tolerant TCP for WAN optimizers, Computer Networks (under revision).

A. Warrier, S. Janakiraman, S. Ha and I. Rhee, DiffQ: Differential Backlog Congestion Control for Multi-hop Wireless Networks, submitted to IEEE Transactions on Networking.

2009

A. Warrier, S. Janakiraman, S. Ha and I. Rhee, DiffQ: Differential Backlog Congestion Control for Multi-hop Wireless Networks, IEEE INFOCOM 2009. PDF Technical Report Video

H. Cai, D. Eun, S. Ha, I. Rhee and L. Xu, Stochastic convex ordering for multiplicative decrease internet congestion control, Computer Networks: The International Journal of Computer and Telecommunications Networks, Volume 53, Issue 3, Feb. 2009, Page(s):365-381, 2009. PDF

2008

S. Ha, I. Rhee and L. Xu, CUBIC: A New TCP-Friendly High-Speed TCP Variant, ACM SIGOPS Operating System Review, Volume 42, Issue 5, July 2008, Page(s):64-74, 2008. PDF

I. Rhee, L. Xu and S. Ha, CUBIC for Fast Long-Distance Networks, IETF Internet Draft, 2008. draft-rhee-tcpm-cubic-02.txt

S. Ha and I. Rhee, Hybrid Slow Start for High-Bandwidth and Long-Distance Networks, PFLDnet, Manchester, UK, 2008. PDF Slides

L. Andrew, C. Marcondes, S. Floyd, L. Dunn, R. Guillier, W. Gang, L. Eggert, S. Ha and I. Rhee, Towards a Common TCP Evaluation Suite, PFLDnet, Manchester, UK, 2008. PDF

A. Warrier, S. Ha, P. Wason, I. Rhee and J. H. Kim, DiffQ: Differential Backlog Congestion Control for Multi-hop Wireless Networks, Demo, IEEE SECON 2008. PDF

S. Ha, A. Warrier and I. Rhee, TCP Problem under high bandwidth delay product networks - Demo III (B), The Future of TCP: Train-wreck or Evolution?, Stanford University, Stanford, CA, 2008. HTML

2007

S. Ha, L. Le, I. Rhee and L. Xu, Impact of Background Traffic on Performance of High-Speed TCP Variant Protocols, Computer Networks: The International Journal of Computer and Telecommunications Networking, Volume 15, Issue 4, Aug. 2007, Page(s):852-865, 2007. PDF

H. Cai, D. Eun, S. Ha, I. Rhee and L. Xu, Stochastic Ordering for Internet Congestion Control and its Applications, IEEE INFOCOM 2007. PDF Slides

H. Cai, D. Eun, S. Ha, I. Rhee and L. Xu, Stochastic Ordering for Internet Congestion Control, PFLDnet, Marina Del Rey, LA, 2007. PDF Slides

2006

S. Ha, Y. Kim, L. Le, I. Rhee and L. Xu, A Step toward Realistic Performance Evaluation of High-Speed TCP Variants, PFLDnet, Nara, Japan, 2006. PDF Slides

S. Ha, Y. Kim, L. Le, I. Rhee and L. Xu, A Step toward realistic evaluation of high-speed TCP protocols, Web-based Technical Report, NCSU 2006. HTML PDF

Patents

M. Chiang, S. Ha, S. Sen and C. Joe-Wong A System for Offering Intelligent Flat Rate (IFR) Data Plans, Invention #12-2726-1, U.S. Provisional Patent Application No. 61/523,835, Aug. 2011.

M. Chiang, S. Ha, S. Sen and C. Joe-Wong A Middleware for Supporting Pricing Solutions in Broadband Networks, Invention #11-2711-1, U.S. Provisional Patent Application No. 61/496,611, June 2011.

M. Chiang, S. Ha, S. Sen and C. Joe-Wong User Interface Design for Time-dependent Pricing Applications, Invention #11-2710-1, U.S. Provisional Patent Application No. 61/496,731, June 2011.

M. Chiang, C. Joe-Wong, S. Ha and S. Sen, System and Methods for Time Dependent Internet Pricing , Invention #11-2686-1, U.S. Provisional Patent Application No. 61/447,896, Mar. 2011.

N. Dukkipati, S. Ha, V. Subramanian and F. Bonomi, Increasing Transmission Rate to a Remote Device In Response to Attributing Information Loss at Not Being a Result of Network Congestion, European Patent#: US 2010060517, Dec 15, 2010, U.S. Publication#: US 2011/0158253 A1, Jun 30, 2011. PDF

Articles

S. Ha and H. Cha, Design and Implementation of Embedded Linux, Programmer's World, Special Issue 3-1, Apr. 2001.

S. Ha and H. Cha, Embedded Linux for Network Devices, Linux@Works, Nov. 2001.

S. Ha and H. Cha, Compare Embedded Linux with Other Real-Time Operating Systems, Linux@Works, Oct. 2001.

Professional Services

General Co-chairs, IEEE INFOCOM Smart Data Pricing Workshop 2013

Co-Editor, Book: Smart Data Pricing, 2013, John Wiley & Sons

TPC Member, IEEE Globecom SAC 2013

TPC Member, IEEE Workshop on Green Multimedia 2013

TPC Member, IEEE PIMRC 2013

TPC Member, WiOpt 2013

TPC Member, IPCCC 2012

TPC Member, NAS 2012

TPC Member, WiOpt 2012

TPC Member, CISS 2012

TPC Member and Organizing Committee, WiOpt 2011

Judge, Princeton Undergraduate Research Symposium 2011

TPC Member, PFLDNeT 2010

Session Chair, CISS 2010

Last updated: 5th January 2013