ICWS Seminar
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DiffQ: Differential Backlog Congestion Control for Wireless Multi-hop Networks

Injong Rhee
Associate Professor, Department of Computer Science 
North Carolina State University.

Abstract:

Congestion control in wireless multi-hop networks is challenging because of
two reasons.
First, broadcast is an inherent feature of wireless networks and motivates
many creative
protocols including opportunistic routing and network coding. These
protocols enable
the use of many diverse, yet dynamically changing routing paths.
Congestion control for these protocols using traditional end-to-end
protocols such as
TCP may result in too conservative rate control. Second, the wireless medium
is shared
among neighboring nodes; thus bandwidth must be allocated fairly among
neighboring flows
that do not necessarily share the same link.
There have been no practical solutions for congestion control for these
networks. Inspired
by existing theoretical solutions of cross-layer optimization, we develop a
protocol, called DiffQ, for congestion control in wireless multi-hop
networks.
DiffQ can support congestion control for network flows that use
either single-path or opportunistic
multi-path routing. The protocol is currently implemented in  Linux 2.6
series and tested
in a network of 46 IEEE 802.11 wireless nodes. It is observed that DiffQ
greatly
improves the efficiency and fairness of existing transport protocols
that use application-level multi-path routing and single-path routing.

Short Bio:

Injong Rhee is Associate Professor of Computer Science at North
Carolina State University. He works primarily on network
protocols for the Internet. His major contributions in the field
include the development of congestion control protocols, called BIC and
CUBIC. Since 2004, these protocols have been the default TCP algorithms
for Linux and are currently being used by more than 40% of Internet
servers around the world and by several tens millions Linux users for
daily Internet communication.  He also has invented several multimedia
streaming and multicast technologies licensed to companies for commercial
applications.  He started a company based on these technologies in 2000
where he developed and launched the world's first video streaming
products and push-to-talk (PTT) VoIP products for cell phones.  His
recent research topics include mobile ad hoc networks, delay/disruption
tolerant networks, and P2P systems. He received NSF Career Award in
1999, NCSU New Inventor's award in 2000.


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ICWS Seminar Series is supported by a grant from Rockwell Collins