The Age of Impatience:
Optimal Replication Schemes
for Opportunistic Networks
Augustin Chaintreau
Thomson Technology Paris Laboratory
Wednesday, November
18, 2pm
Location: BA 5256
Abstract:
As the number of mobile
users increases, and cell phones become more powerful, delivering rich content
to them using a centralized infrastructure becomes both expensive and
inadequate. Here we study an alternative p2p solution, which leverages local
dedicated caches on these devices to opportunistically fulfill other user
requests, in a peer-to-peer manner. In this talk, we address the general problem
of choosing, and maintaining, the right "allocation" of content items to these
caches, to fulfill the demand of all users in a timely manner.
We first show that the allocation's efficiency itself is determined by a
previously overlooked factor, the "impatience" of content requesters. Optimal
allocations corresponding to scenarios following different delay utility
functions can be poles apart. However, we present a general convexity result,
applying to any population of impatient users, which allows to build this
optimal allocation efficiently. We then prove that, although no global cache
state can be maintained in such opportunistic environment, the optimal cache
allocation can be approached by simple reactive replication algorithms that use
only local knowledge. This result is presented here for a homogeneous network;
it generalizes to much more complex system with heterogeneity, leading to some
open questions regarding the connection between human mobility and user
profiling for content sharing.
This is joint work with Joshua Reich from Columbia University.
Bio:
A.
Chaintreau joined Thomson, soon after graduating in 2006 from INRIA-Ecole
Normale Superieure Paris, to work on emerging networking applications and
technologies. His research includes projects on social networking, peer-to-peer
applications on top of wireless and mobile networks, and the challenges and
opportunities arising for routing, resource allocation, congestion control,
caching, content search and recommendation. During his Ph.D he worked in
collaboration with Alcatel Bell, as well as the IBM Watson T. J. Research
Center, on the scalability of TCP controlled P2P delivery systems. He also
worked for a year at Intel Research on the measurement of human mobility and its
consequences on ad-hoc dissemination. The team in Thomson is always looking for
interns and post-doc, and you are welcome to contact him if you think your
research could contribute to one of these topics.
Host of Talk:
Peter Marbach (marbach@cs.toronto.edu)