MY RESEARCH AT NEC LABS

Since joining NEC, I have been focusing on buiding novel systems that could be of immediate interest to product groups. More recently, I have been working on adaptive wireless systems that improve "user experience" under constrained wireless channel capacity.

Along with my colleagues, I have been fortunate to work with the following very productive interns who helped immensely in building these systems:

• Kishore Ramachandran (now at NEC Labs, Princeton)
• Mihaela Enachescu (now at Goldman Sachs)
• Vishnu Navda (now at Miscrosoft Research, Bangalore)
• Sriram Lakshmanan (Georgia Tech)
  
• Marc Blanco

Using beamforming antennas to improve downlink/uplink throughput in WiFi networks

• R2D2: Regulating Beam-shape and Rate as Directionality Meets Diversity. Kishore Ramachandran, Ravi Kokku, Karthik Sundaresan, Marco Gruteser, and Sampath Rangarajan. In the Seventh International Conference on Mobile Systems, Applications, and Services (ACM MOBISYS), Krakow, Poland, June 2009.
  

• Towards Adaptive Beamforming in Indoor Wireless Networks: An Experimental Approach.  Sriram Lakshmanan, Karthik Sundaresan, Ravi Kokku, Amir Khojastepour and Sampath Rangarajan. In INFOCOM minisymposium, Brazil, April 2009.
  

• On the Effectiveness of Switched-beam Antennas in Indoor Environments. Marc Blanco, Ravi Kokku, Kishore Ramachandran, Sampath Rangarajan and Karthik Sundaresan. In the Passive and Active Measurement Conference (PAM), Ohio, April 2008. PDF.

• S3: Slotted Sectored Scheduling in Wireless LANs Samrat Ganguly, Ravi Kokku, Vishnu Navda, Samir Das. Poster at ACM MOBISYS, Puerto Rico, June 2007.

Power and rate control in WLANs for spatial reuse and battery life improvement

• Synchronous Two-phase Rate and Power Control in Wireless LANs. Kishore Ramachandran, Ravi Kokku, Honghai Zhang and Marco Gruteser. In the Sixth International Conference on Mobile Systems, Applications, and Services (ACM MOBISYS), Colorado, June 2008. PDF.
  

• Slotted Symmetric Power Control in Wireless LANs Vishnu Navda, Ravi Kokku, Samrat Ganguly, Samir Das. Technical report.

Wide Area Multipath Data Transfer for faster completion times

• Routelet Placement for Multipath Transport Mihaela Enachescu, Ravi Kokku. In the 5th International Conference on Broadband Communications, Networks and Systems (BROADNETS), September 2008, London, UK.  PDF. Best Paper Award.
  

• A Multipath Background Network Architecture Ravi Kokku, Aniruddha Bohra, Samrat Ganguly, Arun Venkataramani. In the 26^th IEEE conference on Communications (INFOCOM), May 2007, Anchorage, Alaska. Detailed Report. Source code.  Alternate implementation and validation.
  

Mobile Services

• Enabling Location-Specific Real-time Mobile Applications. Ravi Kokku, Karthik Sundaresan and Geoff Jiang. In Third ACM MOBIARCH, Seattle, WA, August 2008. PDF, SLIDES.

PAST RESEARCH AT UT-AUSTIN

Wide-area Data Replication

• Safe Speculative Replication Mike Dahlin, Arun Iyengar, Ravi Kokku, Amol Nayate, Arun Venkataramani, Praveen Yalagandula. Technical report unifying principles from several papers below, 2007.

• PATENT: Method and system for background replication of data objects, US Patent # 7,418,494.

• NPS: A Non-interfering Deployable Web Prefetching System  Ravi Kokku, Praveen Yalagandula, Arun Venkataramani and Mike Dahlin. In the 4th USENIX Symposium on Internet Technologies and Systems (USITS), Mar 2003, Seattle, USA. Source Code. Slides.

• TCP Nice: A Mechanism for Background Transfers Arun Venkataramani, Ravi Kokku and Mike Dahlin. In the 5th Symposium on Operating Systems Design and Implementation (OSDI), Dec 2002, Boston, USA. Also appears in ACM SIGOPS Operating Systems Review, Volume 36 , Issue SI Winter 2002. Detailed Report. Source code.

• Operating System Support for Massive Replication Arun Venkataramani, Ravi Kokku, Mike Dahlin. In the proceedings of the 10th ACM SIGOPS European Workshop (SIGOPS), 2002, St. Emilion, France.

• The potential costs and benefits of long-term prefetching Arun Venkataramani, Praveen Yalagandula, Ravi Kokku, Sadia Sharif and Mike Dahlin. In the Computer Communications journal, 25 (4) (2002) pp. 367-375. Also appeared in the 6th International Workshop on Web Caching and Content Distribution (WCW 2001) , June 2001,Boston, USA. Selected as an Award Paper and forwarded to the Computer Communications journal. Detailed Report. Slides.

Multi-service Virtualized Routers

• Run-time System for Scalable Network Services Upendra Shevade, Ravi Kokku, Harrick Vin. In the 27^th IEEE Conference on Computer Communications (INFOCOM), April 2008, Phoenix, Arizona. 
  

• Processor Scheduler for Multi-Service Routers, Ravi Kokku, Upendra Shevade, Nishit Shah, Ajay Mahimkar, Taewon Cho, Harrick Vin. In the 27^th IEEE Real Time Systems Symposium (RTSS), December 2006, Rio De Janeiro, Brazil.

• SHARE: Run-time System for High-performance Virtualized Routers. PhD Thesis. The University of Texas at Austin, August 2005

• Supporting Run-time Adaptation in Packet Processing Systems Vinod Balakrishnan, Ravi Kokku, Aaron Kunze, Harrick Vin, and Erik Johnson. TR-04-46, UT-Austin, 2004.

• A Case for Run-time Adaptation in Packet Processing Systems Ravi Kokku,  Taylor Riche', Aaron Kunze, Jayaram Mudigonda, Jamie Jason, Harrick Vin. In the 2nd Workshop on Hot Topics in Networks (HOTNETS), Nov 2003, Cambridge, MA, USA. Also appears in ACM SIGCOMM Computer Communication Review, Volume 34, Issue 1 (January 2004). Detailed Report. Slides.

Other Miscellaneous Work

• Half-pipe Anchoring: An Efficient Technique for Multiple Connection Handoff Ravi Kokku, Ram Rajamony, Lorenzo Alvisi and Harrick Vin. In the 10th International Conference on Network Protocols (ICNP), Nov 2002, Paris, France. Slides.

• PATENT: Distributed Shared Memory for Server Clusters, US Patent # 6,829,637.

• DDSCHED: A Distributed Dynamic Real-time Scheduling Algorithm Anup Bhattacharjee, Ravi Kokku, Rajib Mall and Ajit Pal. In the special issue of Parallel and Distributed Computing Practices journal. Vol 1. No 4, December 1998. Also appeared at the 5th International Conference on Advanced Computing (ADCOMP), Dec 1997, Chennai, India. Selected as an Award Paper and forwarded to the PDCP journal.