Principal Researcher
Microsoft Research

NEW:

Contact Information
Brief Bio
Research Projects
Publications: Recent, All
Talks: Recent, All
Teaching and Mentoring
Other Professional Activities
Miscellaneous

Contact Information

Microsoft Research India
"Scientia"
196/36 2nd Main, Sadashivnagar
Bangalore 560 080
India
Tel: +91 (80) 6658-6004
Fax: +91 (80) 2361-4657
E-mail: padmanab@microsoft.com

Brief Bio
I am a Principal Researcher at Microsoft Research India, where I founded and have been managing the Mobility, Networks, and Systems group since Spring 2007. I was previously with Microsoft Reseach Redmond for 8.5 years. My research interests lie broadly in networked systems. My current work centers on (a) the intersection of sensor systems and mobile computing, and separately on (b) network management. My past projects have spanned a range of areas, including network measurement, wireless networking, RFID, geolocation, network tomography, and peer-to-peer networking. The technologies developed in some of these projects (e.g., the ProbeGap bandwidth probing tool and the GeoCluster technique for learning IP-location mapping) have been transferred to Microsoft's product groups while others (e.g., the RADAR WLAN-based user localization system) have been made available through Microsoft's technology licensing program.

I obtained a Ph.D. in Computer Science from the University of California at Berkeley in September 1998. Professor Randy Katz was my advisor. I had previously obtained an M.S. in Computer Science from UC Berkeley in 1995 (advised by Professor Domenico Ferrari) and a B.Tech. in Computer Science and Engineering from the Indian Institute of Technology, Delhi in 1993.

My Ph.D. thesis, titled Addressing the Challenges of Web Data Transport, proposed two novel techniques, TCP Session and TCP Fast Start, to bridge the disconnect between HTTP and TCP. These techniques provided an alternative to my prior work on persistent-connection HTTP (P-HTTP) done during my internship with Dr. Jeffrey Mogul at DEC Western Research Lab (now part of HP Labs). The ideas of persistent connections and pipelining in P-HTTP have since been adopted by the IETF HTTP/1.1 standard (RFC 2616).

Detailed lists of my publications, talks, and patents appear on separate pages.

Research Projects

NetProfiler
Cooperative Networking (CoopNet)
PeerMetric
Passive Network Tomography
IP2Geo
Web Measurements
RADAR

Recent Publications

NetPrints: Diagnosing Home Network Misconfigurations Using Shared Knowledge
B. Aggarwal, R. Bhagwan, T. Das, S. Eswaran, V. N. Padmanabhan, G. M. Voelker
To appear in NSDI, Boston, MA, USA
April 2009

Nericell: Rich Monitoring of Road and Traffic Conditions using Mobile Smartphones
P. Mohan, V. N. Padmanabhan, and R. Ramjee
ACM SenSys, Raleigh, NC, USA
November 2008

Distributed Sensing using Mobile Smartphones
V. N. Padmanabhan
Invited article in IT Magazine
September 2008

10 Networking Papers: Elegance and Insight
V. N. Padmanabhan
Invited paper in the Recommended Reading Series
ACM Computer Communication Review
July 2008

SixthSense: RFID-based Enterprise Intelligence
L. Ravindranath, V. N. Padmanabhan, and P. Agrawal
ACM/USENIX MobiSys, Breckenridge, Colorado, USA
June 2008

Addressing Email Loss with SureMail: Measurement, Design, and Evaluation
S. Agarwal, V. N. Padmanabhan, and D. A. Joseph
USENIX Technical Conference, Santa Clara, CA, USA
June 2007

COMBINE: Leveraging the Power of Wireless Peers through Collaborative Downloading
G. Ananthanarayanan, V. N. Padmanabhan, L. Ravindranath, and C. A. Thekkath
ACM/USENIX MobiSys, San Juan, Puerto Rico
June 2007

Collaborative Downloading for Multi-homed Wireless Devices
G. Ananthanarayanan, V. N. Padmanabhan, C. A. Thekkath, and L. Ravindranath
IEEE HotMobile, Tucson, AZ, USA
February 2007

A Study of End-to-End Web Access Failures
V. N. Padmanabhan, S. Ramabhadran, S. Agarwal, and J. Padhye
CoNEXT 2006, Lisbon, Portugal
December 2006
PostScript, PDF
(This paper supersedes Microsoft Research Technical Report MSR-TR-2005-29, March 2005 (PostScript, PDF))

WiFiProfiler: Cooperative Diagnosis in Wireless LANs
R. Chandra, V. N. Padmanabhan, and M. Zhang
ACM/USENIX MobiSys 2006, Uppsala, Sweden
June 2006
PostScript, PDF

Analyzing and Improving a BitTorrent Network's Performance Mechanisms
A. R. Bharambe, C. Herley, and V. N. Padmanabhan
IEEE Infocom 2006, Barcelona, Spain
April 2006
PostScript, PDF
(An earlier version of this paper is available as Microsoft Research Technical Report MSR-TR-2005-03, February 2005 (PostScript, PDF))

SureMail: Notification Overlay for Email Reliability
S. Agarwal, V. N. Padmanabhan, and D. A. Joseph
ACM HotNets, College Park, MD, USA
November 2005
PostScript, PDF

Estimation of Link Interference in Static Multi-hop Wireless Networks
J. Padhye, S. Agarwal, V. N. Padmanabhan, L. Qiu, A. Rao, and B. Zill
ACM/USENIX Internet Measurement Conference, Berkeley, CA, USA
October 2005

NetProfiler: Profiling Wide-Area Networks Using Peer Cooperation
V. N. Padmanabhan, S. Ramabhadran, and J. Padhye
Proceedings of the Fourth International Workshop on Peer-to-Peer Systems (IPTPS), Ithaca, NY, USA
February 2005
PostScript, PDF

The Impact of Heterogeneous Bandwidth Constraints on DHT-Based Multicast Protocols
A. R. Bharambe, S. G. Rao, V. N. Padmanabhan, S. Seshan, and H. Zhang
Proceedings of the Fourth International Workshop on Peer-to-Peer Systems (IPTPS), Ithaca, NY, USA
February 2005

Supporting Spectators in Online Multiplayer Games
A. R. Bharambe, V. N. Padmanabhan, and S. Seshan
ACM SIGCOMM Workshop on Hot Topic in Networks (HotNets-III), San Diego, CA, USA
November 2004
PostScript, PDF

Bandwidth Estimation in Broadband Access Networks
K. Lakshminarayanan, V. N. Padmanabhan, and J. Padhye
ACM/USENIX Internet Measurement Conference, Taormina, Sicily, Italy
October 2004
PostScript, PDF
(An earlier version of this paper is available as Microsoft Research Technical Report MSR-TR-2004-44, May 2004 (PostScript, PDF))

Securing Routing in Open Networks Using Secure Traceroute
G. Mathur, V. N. Padmanabhan, and D. R. Simon
Microsoft Research Technical Report MSR-TR-2004-66
July 2004
PostScript, PDF

Supporting Heterogeneity and Congestion Control in Peer-to-Peer Multicast Streaming
V. N. Padmanabhan, H. J. Wang, and P. A. Chou
Proceedings of the Third International Workshop on Peer-to-Peer Systems (IPTPS), San Diego, CA, USA
February 2004
PostScript, PDF

Resilient Peer-to-Peer Streaming
V. N. Padmanabhan, H. J. Wang, and P. A. Chou
IEEE ICNP 2003, Atlanta, GA, USA
November 2003
PostScript, PDF
(An expanded version of this paper is available as Microsoft Research Technical Report MSR-TR-2003-11, March 2003 (PostScript, PDF))

Some Findings on the Network Performance of Broadband Hosts
K. Lakshminarayanan and V. N. Padmanabhan
ACM/USENIX Internet Measurement Conference, Miami, FL, USA
October 2003
PostScript, PDF
(An earlier version of this paper is available as Microsoft Research Technical Report MSR-TR-2003-15, March 2003 (PostScript, PDF))

Impact of Interference on Multi-hop Wireless Network Performance
K. Jain, J. Padhye, V. N. Padmanabhan, and L. Qiu
ACM Mobicom 2003, San Diego, CA, USA
September 2003
PostScript, PDF

Layered Multiple Description Coding
P. A. Chou, H. J. Wang, and V. N. Padmanabhan
IEEE Packet Video Workshop, Nantes, France
April 2003

Server-based Inference of Internet Link Lossiness
V. N. Padmanabhan, L. Qiu, and H. Wang
IEEE Infocom 2003, San Francisco, CA, USA
April 2003
PostScript, PDF
(An earlier version of this paper is available as Microsoft Research Technical Report MSR-TR-2002-39, May 2002 (PostScript, PDF))

Passive Network Tomography Using Bayesian Inference
V. N. Padmanabhan, L. Qiu, and H. Wang
Short Paper in the Proceedings of ACM SIGCOMM Internet Measurement Workshop, Marseille, France
November 2002
PostScript, PDF

Secure Traceroute to Detect Faulty or Malicious Routing
V. N. Padmanabhan and D. R. Simon
ACM SIGCOMM Workshop on Hot Topic in Networks (HotNets-I), Princeton, NJ, USA
October 2002
PostScript, PDF

Geographic Properties of Internet Routing
L. Subramanian, V. N. Padmanabhan, and R. H. Katz
USENIX Technical Conference, Monterey, CA, USA
June 2002
PostScript, PDF
(This paper obsoletes Microsoft Research Technical Report MSR-TR-2001-89, September 2001 (PostScript, PDF))

Statistical Identification of Encrypted Web Browsing Traffic
Q. Sun, D. R. Simon, Y. Wang, W. Russell, V. N. Padmanabhan, and L. Qiu
IEEE Symposium on Security and Privacy, Oakland, CA, USA
May 2002

Distributing Streaming Media Content Using Cooperative Networking
V. N. Padmanabhan, H. J. Wang, P. A. Chou, and K. Sripanidkulchai
ACM NOSSDAV, Miami Beach, FL, USA
May 2002
PostScript, PDF
(An expanded version of this paper is available as Microsoft Research Technical Report MSR-TR-2002-37, April 2002 (PostScript, PDF))

The Case for Cooperative Networking
V. N. Padmanabhan and K. Sripanidkulchai
Proceedings of the First International Workshop on Peer-to-Peer Systems (IPTPS), Cambridge, MA, USA
March 2002
PostScript, PDF
(This is a slightly expanded version of the original IPTPS paper (PostScript, PDF) that includes an addendum.)

Network Tomography Using Passive End-to-End Measurements
V. N. Padmanabhan and L. Qiu
DIMACS Workshop on Internet and WWW Measurement, Mapping and Modeling, Piscataway, NJ, USA
February 2002
PostScript, PDF

Server-Centric View of Internet Performance: Analysis and Implications
L. Qiu and V. N. Padmanabhan
Microsoft Research Technical Report MSR-TR-2001-78
September 2001
PostScript, PDF

An Investigation of Geographic Mapping Techniques for Internet Hosts
V. N. Padmanabhan and L. Subramanian
Proceedings of ACM SIGCOMM 2001, San Diego, CA, USA
August 2001
PostScript, PDF

Determining the Geographic Location of Internet Hosts
V. N. Padmanabhan and L. Subramanian
Extended abstract in Proceedings of ACM SIGMETRICS 2001, Boston, MA, USA
June 2001
PostScript, PDF

How Network Asymmetry Affects TCP
H. Balakrishnan and V. N. Padmanabhan
IEEE Communications Magazine
April 2001

On the Placement of Web Server Replicas
L. Qiu, V. N. Padmanabhan, and G. Voelker
Proceedings of IEEE Infocom 2001, Anchorage, AK, USA
April 2001
PostScript, PDF

TCP Performance Implications of Network Asymmetry
H. Balakrishnan, V. N. Padmanabhan, G. Fairhurst, and M. Sooriyabandara
Internet Draft, IETF PILC Working Group
March 2001

LandLoc: Landmark-based User Location
V. N. Padmanabhan
Microsoft Research Technical Report MSR-TR-2001-23
January 2001
PostScript, PDF

The Content and Access Dynamics of a Busy Web Site: Findings and Implications
V. N. Padmanabhan and L. Qiu
Proceedings of ACM SIGCOMM 2000, Stockholm, Sweden
August 2000
PostScript, PDF
(An earlier version appeared as Microsoft Research Technical Report MSR-TR-2000-13, February 2000 (PostScript, PDF))

The Content and Access Dynamics of a Busy Web Server
V. N. Padmanabhan and L. Qiu
Extended abstract in Proceedings of ACM SIGMETRICS 2000, Santa Clara, CA, USA
June 2000
PostScript, PDF

A Software System for Locating Mobile Users: Design, Evaluation, and Lessons
P. Bahl, V. N. Padmanabhan, and A. Balachandran
April 2000
PostScript, PDF
(An earlier version appeared as Microsoft Research Technical Report MSR-TR-2000-12, February 2000 (PostScript, PDF))

RADAR: An In-Building RF-Based User Location and Tracking System
P. Bahl and V. N. Padmanabhan
Proceedings of IEEE Infocom 2000, Tel-Aviv, Israel
March 2000
PostScript, PDF
(This is an updated version of Microsoft Research Technical Report MSR-TR-99-12, February 1999 (PostScript, PDF))

Recent Talks

Resilient Peer-to-Peer Streaming
Invited talks at Carnegie Mellon University and the University of California at Berkeley
March 2003
PostScript, PDF

Secure Traceroute to Detect Faulty or Malicious Routing
ACM SIGCOMM Workshop on Hot Topic in Networks (HotNets-I), Princeton, NJ, USA
October 2002
PostScript, PDF

CoopNet: Cooperative Networking
Invited talk at the Georgia Institute of Technology, Atlanta, GA, USA
September 2002
PostScript, PDF

Distributing Streaming Media Content Using Cooperative Networking
ACM NOSSDAV, Miami Beach, FL, USA
May 2002
PostScript, PDF

Server-based Characterization and Inference of Internet Performance
Invited talk at IPAM Workshop on Large Scale Communication Networks
University of California, Los Angeles, CA, USA
March 2002
PostScript, PDF

Locating Internet Hosts
Computer Science Colloquium, Harvard University, Cambridge, MA, USA
June 2001
PostScript, PDF

Locating Internet Hosts
University of Washington, Seattle, WA, USA
November 2000

RADAR: An In-Building RF-Based User Location and Tracking System
IEEE Infocom 2000, Tel Aviv, Israel
March 2000
PostScript, PDF

The Content and Access Dynamics of a Busy Web Server
MSR Networking Workshop, Cambridge, UK
January 2000
PostScript, PDF

RADAR: An In-Building RF-Based User Location and Tracking System
MSR Networking Workshop, Cambridge, UK
January 2000
PostScript, PDF

TCP Performance Implications of Network Asymmetry
PILC Working Group, 46th IETF, Washington, DC, USA
November 1999
PostScript, PDF

Teaching and Mentoring

I have worked with (or am presently working with) several excellent students during and after their internships at Microsoft Research:

• Lili Qiu, Cornell University (Summer 1999)
• Anand Balachandran, UC San Diego (Fall 1999, co-mentored with Victor Bahl)
• Lakshminarayanan Subramanian, UC Berkeley (Summer 2000)
• Kay Sripanidkulchai, CMU (Summer 2001)
• Karthik Lakshminarayanan, UC Berkeley (Summer 2002)
• Ashwin Bharambe, CMU (Summer 2003 & Summer 2004)
• Gaurav Mathur, BITS Pilani (Summer 2003)
• Sriram Ramabhadran, UC San Diego (Summer 2004)
• Sreedhar Veeravalli, IIT Guwahati (Summer 2004, co-mentored with Jitu Padhye)
• Dilip Antony Joseph, UC Berkeley (Summer 2005)
• Vladimir Brik, U Wisconsin at Madison (Summer 2006)
• Nikitas Liogkas, UCLA (Summer 2006, co-mentored with Sharad Agarwal)

I have held affiliate faculty appointments in the Electrical Engineering and Computer Science & Engineering departments at the University of Washington. I taught a graduate networking class in the CSE department in Spring 2001. I am on the advisory board for the Wireless Communications Technology program at UW Extension. I have also served on student thesis committees at UW and elsewhere:

• Alhussein Abouzeid, M.S. (1999), Ph.D. (2001), University of Washington
• Marcelo Albuquerque, M.S. (2001), University of Washington
• Lakshminarayanan Subramanian, M.S. (2002), University of California at Berkeley
• Ashwin Bharambe, Ph.D. (expected 2007), Carnegie Mellon University
• Manish Kumar C., M.Sc. (Engg.) (2008), Indian Institute of Science

Other Professional Activities

Editorial board positions:

• ACM SIGCOMM Computer Communication Review (CCR), 2005-2007
• IEEE Transactions on Mobile Computing, 2002-2004
• IEEE/ACM Transactions on Networking, 2002-2004

Chair positions:

• General Co-Chair for ACM SIGCOMM 2010 in New Delhi
• Program Chair for IEEE HotWeb 2008
• Program Co-Chair for ACM/USENIX Internet Measurement Conference (IMC) 2005
• Workshop and Program Co-chair for ACM NOSSDAV 2004
• Invited Talks Chair for WISARD 2008
• Vice Chair for WWW 2006 Pervasive Web & Mobility Track
• Industrial Liaison Co-Chair for ACM Mobicom 2005
• Tutorials Co-Chair for ACM Mobicom 2000

Program committee membership:

• ACM/USENIX MobiSys: 2007
• ACM SIGCOMM: 2004, 2007
• CoNEXT: 2006
• ACM SIGMETRICS: 2003, 2008
• COMSNETS: 2009
• COMSWARE: 2008
• ACM Mobicom: 2000, 2001, 2002
• IEEE Infocom: 2001, 2002, 2005
• ACM HotNets: 2005
• ACM Internet Measurement Conference: 2002, 2005
• ACM NOSSDAV: 2000, 2002, 2003, 2004
• International Workshop on Peer-to-Peer Systems (IPTPS): 2007 
• International Conference on Distributed Computing Systems (ICDCS): 2005
• SPIE/ACM Multimedia Computing and Networking (MMCN): 2002, 2003
• IEEE International Conference on Network Protocols (ICNP): 2002, 2003
• International World Wide Web Conference (WWW): 2002, 2003, 2006
• ACM Workshop on Wireless Mobile Multimedia (in conjunction with ACM Mobicom): 1999, 2000
• Performance and Architecture of Web Servers (in conjunction with ACM SIGMETRICS): 2000, 2001

Miscellaneous

Here are some videos and articles on research projects I am or have been involved with.

Press coverage:

ProbeGap: PC World
Suremail: Computerworld, Computerworld, InformationWeek
COMBINE: The Hindu, Business Line
Nericell (previously known as TrafficSense): PC World, Seattle Post-Intelligencer, ComputerWorld Canada, The Economic Times, Deccan Chronicle, Rediff
SixthSense: Ubergizmo, ComputerWorld Canada

Videos:

BARWAN Project, UC Berkeley(see if you can spot my two seconds of fame!)
Mobile Communications Research at Microsoft(it should be a lot easier to spot me in this one)