I am currently a member of the Applied Research Group at the Sprint Advanced Technology Labs (ATL).   I   got my Phd in 2004 from the  Electrical and Systems Engineering Dept.  at the University of Pennsylvania, where I was a part of the Multimedia and Networking Lab. My thesis was primarily focused on traffic-engineering in IP networks, and supervised by Dr. Roch Guèrin.  A long time ago,  I obtained my Bachelor's in Electronics Engineering from Regional Engineering College, Nagpur  in June 1997 and my Masters in Telecommunication from the Indian Institute of Science Bangalore in Dec 1998. 

At Penn, I worked on developing routing and load-balancing algorithms that are practical to implement on the existing IP routing architecture and as an intern at Sprint, verified these algorithms with  measurements from the IP backbone. My current interests, after joining Sprint Labs have expanded  into conducting performance analysis of cellular data networks and large-scale network data-mining.    Typically the flavour of problems I like to tackle involve identifying bottleneck components in practical systems or architectures and developing techniques that can address them (a.k.a Engineering !) .  In terms of approach, I enjoy bringing well-known mathematical theories to bear on practical problems at hand as well as conducting extensive measurement-based analysis. 

Some of the projects that I am actively working on in these areas are listed below along with recent publications in each of the projects.

CURRENT PROJECT AREAS :

Cross-Layer Performance Optimization of 3G Networks

This is a multi-faceted project aimed at understanding the dynamics of Sprint's high-speed 3G cellular network, how well applications perform on them, and in parallel improving general network performance through cross-layer optimization. The former portion of the project involves wide-scale measurement of the 3G network using various Network/MAC layer tools, client-based monitoring and conducting detailed cross-layer analysis of the logs with the specific objective of characterizing the variability of the wireless channel, and how it affects the overlying application.

1. "TCP Over CDMA2000 Networks: A Cross-Layer Measurement Study", Karim Mattar, Ashwin Sridharan, Hui Zang, Ibrahim Matta, Azer Bestavros, Proceedings of Passive and Active Measurement Conference, April 2007. [Link]
2. "Experiences in a 3G Network : Interplay between the Wireless Channel and Applications", Xin Liu, Ashwin Sridharan, Sridhar Machiraju, Mukund Seshadri, Hui Zang. Proceedings of ACM MOBICOM, September 2008.
   

The latter part of the project is more analytical in nature . The broad goal of this portion of the project is to develop analytical models that capture the behaviour of TCP on cellular channels and leverage them to improve the MAC layer in terms of energy efficiency as well as TCP throughput.

1. "TCP-Aware Resource Allocation in CDMA Networks", Majid Ghaderi, Ashwin Sridharan, Hui Zang,  Don Towsley, Rene Cruz. Proceedings of ACM MOBICOM,  August, 2006.
2. "Modeling TCP in a Multi-Rate, Multi-User CDMA System", Majid Ghaderi, Ashwin Sridharan, Hui Zang, Don Towsley, Rene Cruz. Proceedings of IFIP-TC6 Networking Conference, May 2007. [Link]
   

Scheduling and Optimization of the EV-DO Uplink

The 1xEVDO Rev. A cellular technology offers a wide range of parameters that can be modified by the network operator to improve performance on uplink transmissions from the mobile device to the network. They include a token-bucket like structure for power-usage,  multiple transmission rates and corresponding power values.  This project aims at developing an algorithmic framework that will leverage these "knobs", and develop sound techniques to tune the uplink parameters for optimal performance, while taking into consideration features like MAC layer Hybrid ARQ, distributed scheduling etc.

1. "Distributed Uplink Scheduling in CDMA Networks", Ashwin Sridharan, Ramesh Subarraman, Roch Guèrin, Proceedings of IFIP-TC6 Networking Conference,  May s2007. [Link]
   

Large Scale Network Data Analysis

Sprint, as a network operator, is a natural repository of a vast trove of information pertaining to wireless network usage examples of which include call-quality, call-duration etc.  I am involved in developing techniques that can mine the data to improve Sprint network performance as well as identify social networks.

1. "Mobile Call Graphs : Beyond Power-law and Lognormal Distributions", Mukund Seshadri, Sridhar Machiraju, Ashwin Sridharan, Jean Bolot, Christos Faloutsos, Jure Leskovec. Proceedings of SIGKDD, 2008.

PUBLICATIONS (in Chronological Order)                                                                                                                                        [Return to Top]

Disclaimer : Links to the electronic articles are provided solely for personal usage. In many cases, copyright of the articles is owned by the journal itself.

    Conference Publications

1. "Blocking in All-Optical Networks", Ashwin Sridharan, Kumar N. Sivarajan, INFOCOM 2000, Tel Aviv Israel  [.ps] [.pdf]
2. "Study of Distributed Resource Allocation in Cellular Systems", A. Anand, Ashwin Sridharan, Kumar N. Sivarajan, IEEE 53rd Vehicular Technology Conference, Volume 2, May 6-9 2001 [.pdf]
   
3. "On the Impact of Aggregation on Traffic-Aware Routing", Ashwin Sridharan, C. Diot, R. Guèrin, J. Jetcheva, N. Taft, Proceedings of ITC 2002,  Salvador, Brazil [.ps]  [.pdf]
4. "Achieving Near Optimal Traffic Engineering Solutions in Current OSPF/ISIS Networks", Ashwin Sridharan, R. Guèrin, C. Diot Proceedings of INFOCOM 2003,  San Fransisco, USA   [.pdf] 
5. "On the Correlation between Route Dynamics and Routing Loops", Ashwin Sridharan, Sue. B. Moon and C. Diot, Proceedings of IMC 2003, Miami, Florida, USA[.pdf]
6. "Making IGP Routing Robust to Link Failures", Ashwin Sridharan and Roch Guèrin, Proceedings of Networking 2005, University of Waterloo, Canada. [Link]
7. "The Problem of Synthetically Generarting IP Traffic Matrices: Initial Recommendations", Antonio Nucci and Ashwin Sridharan and Nina Taft, Computer Communications Review (CCR), July 2005. [.pdf]
8. "TCP-Aware Resource Allocation in CDMA Networks", Majid Ghaderi, Ashwin Sridharan, Hui Zang, Don Towsley and Rene Cruz, ACM MOBICOM 2006.[Link]
9. "Is Sampled Data Sufficient for Anomaly Detection ?", Jianning Mai, Chen-Nee Chuah, Ashwin Sridharan, Tao Ye and Hui Zang, ACM Internet Measurement Conference (IMC) 2006.[Link]
   
10. "TCP Over CDMA2000 Networks: A Cross-Layer Measurement Study", Karim Mattar, Ashwin Sridharan, Hui Zang, Ibrahim Matta, Azer Bestavros, Proceedings of Passive and Active Measurement Conference, April 2007. [Link]
    
11. "Distributed Uplink Scheduling in CDMA Networks", Ashwin Sridharan, Ramesh Subarraman, Roch Guèrin, Proceedings of IFIP-TC6 Networking Conference, 2007. [Link]
    
12. "Modeling TCP in a Multi-Rate, Multi-User CDMA System", Majid Ghaderi, Ashwin Sridharan, Hui Zang, Don Towsley, Rene Cruz. Proceedings of IFIP-TC6 Networking Conference, 2007. [Link]  [Talk] 
    
13. "Mobile Call Graphs : Beyond Power-law and Lognormal Distributions", Mukund Seshadri, Sridhar Machiraju, Ashwin Sridharan, Jean Bolot, Christos Faloutsos, Jure Leskovec. Proceedings of SIGKDD, 2008.
    
14. "Experiences in a 3G Network : Interplay between the Wireless Channel and Applications", Xin Liu, Ashwin Sridharan, Sridhar Machiraju, Mukund Seshadri, Hui Zang. Proceedings of ACM MOBICOM, 2008.
    

1. "Blocking in All-Optical Networks", Ashwin Sridharan, Kumar N. Sivarajan, IEEE/ACM Transactions on Networking, April 2004[.ps][.pdf]
   
2. "Performance Analysis of Channelized Cellular Systems with Dynamic Channel Allocation", A. Anand, Ashwin Sridharan, Kumar N. Sivarajan, IEEE Transactions on Vehicular Technology, Volume 52, Issue 4, July 2003 [.pdf]
   
3. "Achieving Near Optimal Traffic Engineering Solutions in Current OSPF/ISIS Networks", Ashwin Sridharan, Roch Guèrin, C. Diot, accepted for publication in IEEE/ACM Transactions on Networking.
   
4. "On the Impact of Packet Sampling on Portscan Detection", Jianning Mai, Ashwin Sridharan, Chen-Nee Chuah, Hui Zang and Tao Ye, accepted for publication in Special Issue of IEEE Journal of Selected Areas in Communications.[Link]
   
5. "TCP-Aware Channel Allocation in  Wireless Networks", Majid Ghaderi, Ashwin Sridharan, Hui Zang, Don Towsley and Rene Cruz. IEEE Transactions on Mobile Computing, Vol. 8. January 2009.
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PROFESSIONAL ACTIVITIES

I have actively participated in several Technical Program Committees (NETWORKING 2006, CONNEXT 2007, INFOCOM 2007, IMC 2008) and am a frequent reviewer for several journals (IEEE Trans. on Networking, IEEE Trans. on Wireless Commn., IEEE/JSAC Special sAreas on Commn.)