Toronto Networking Seminar

Organized by Department of Computer Science and Department of Electrical and Computer Engineering, University of Toronto

Utility Maximization for P2P Applications and Its Application in Optimizing Multi-party Conferencing

Jin Li
Microsoft Research
Redmond, WA


Friday, April 16, 2pm
Location: BAB024 (Bahen Centre Basement)


Peer-to-Peer (P2P) applications are tremendously popular on today's Internet, and applications like file sharing perform well even with thousands or millions of peers. However, the design of the majority of P2P systems does not strive to achieve any systematic optimization of social welfare to all peers under a resource sharing constraint. This may well be the next step in improving the performance of P2P systems.

In this talk, we study the problem of utility maximization in P2P applications, in which aggregate application- specific utilities are maximized by running distributed algorithms on P2P nodes. Using recent discoveries in optimal tree structure for P2P content delivery, we develop a new formulation for multicast utility maximization problem. This formulation is unique in the sense that it not only eliminates some mathematical difficulties as compared to previous formulations, but also leads to practical solutions. We develop Primal and Primal-dual distributed algorithms to maximize the aggregate utility. We prove that these algorithms converge to the optimal solution of the utility maximization problem exponentially fast. Furthermore, they can be implemented by utilizing only the end-to-end delay measurement between P2P nodes. As such, it can be readily deployed on today's Internet. To support this claim, we have implemented the Primal-dual algorithm to design a peer-assisted multi-party conferencing system and evaluated its performance through actual experiments on a small scale testbed, as well as on the Internet.


Dr. Jin Li is currently a Principal Researcher managing the Communication System team at Microsoft Research, (Redmond, WA). He received his Ph.D. in electrical engineering from Tsinghua University (Beijing, China) in 1994. From 1994 to 1996, he served as a Research Associate at the University of Southern California (USC). From 1996 to 1999, he was a Member of the Technical Staff at the Sharp Laboratories of America (SLA), (Camas, WA), and represented the interests of SLA in the JPEG2000 and MPEG4 standardization efforts. He joined Microsoft Research, first as a Project Leader at Microsoft Research Asia (Beijing, China) from 1999 to 2000, and then moved back to Redmond in 2001. From 2000, Dr. Li has also served as an Adjunct Professor in the Electrical Engineering Department, Tsinghua University (Beijing, China).

Dr. Li has 100+ referred conference and journal papers in a diversified research field, with interests cover audio/image/video compression, virtual environment and graphic compression, audio/video streaming, and VoIP and video conferencing, and P2P networking. His research group (Communication System) supports Microsoft real-time communication (RTC) group, which develops the audio/video engine for Microsoft Unified Communication systems. His invention has been integrated into many Microsoft products, such as Microsoft Office Communicator, Microsoft Live Meeting, Live Messenger, Live Mesh, Windows 7 (Teredo), etc.. He holds 20+ issued US patents, with more than three dozens pending. He was the general chair for 17th International Packet Video workshop 2009 (PV 2009), and was on the organization committee/TPC/associate editors on many conferences and journals. He was the recipient of the 1994 Ph.D. thesis award from Tsinghua University, the 1998 Young Investigator Award from SPIE Visual Communication and Image Processing, and the Best Paper Award from 2009 IEEE International Conference of Multimedia.

Host of Talk:

Baochun Li (