|
|
|
|
Reliable Data Transport Protocols for MANETs
|
Multihop wireless networks using IEEE 802.11 possess several properties, which are different to the wired Internet for which the widely deployed TCP NewReno implementation has been optimized. Opposed to wired networks, in IEEE 802.11 networks the wireless channel is a scarce resource shared among nodes within their radio range. Furthermore, channel capture, hidden and exposed terminal effects, and the IEEE 802.11 medium access control constitute features of wireless multihop networks not present in a wired IP network. In fact, for multihop wireless networks most losses experienced by TCP are due to packet drops at the link layer and not due to buffer overflow. Furthermore, since TCP NewReno's congestion control is based on lost data packets, the size of its congestion window is overshooting rather than proactively sense incipient congestion by monitoring the network traffic. Because of all these features, TCP NewReno possesses quite poor performance in multihop wireless networks, as well as exhibits severe unfairness among competing TCP flows.
Most of the research in the area of reliable transport protocols for MANET is still in its early stages, so there are numerous challenges:
- How can a cross-layer optimization of congestion control of TCP, MANET routing protocol, and IEEE 802.11 be performed? Is cross-layer information exchange required for optimizing throughput and fairness?
- How can a rate-based data transport protocol for MANET be implemented such that it remains TCP-compatible and TCP-friendly as well as detects congestion timely?
- How can a reliable data transport protocol over a hybrid network comprising of a multihop wireless part and a wired part be implemented? How can the end-to-end semantics be retained in such a network?
|
|
Funding
|
|
German Science Foundation (DFG): May 1, 2007 till April 30, 2009 |
|
Publications
|
|
S. ElRakabawy, A. Klemm, and C. Lindemann, TCP with Gateway Adaptive Pacing for Multihop Wireless Networks with Internet Connectivity, Elsevier Computer Networks Journal, Special Issue on Performance of Wireless Networks, 52, pp. 180-198, 2008. PDF
S. ElRakabawy, A. Klemm, and C. Lindemann, Gateway Adaptive Pacing
for TCP across Multihop Wireless Networks and the Internet, Proc. 9th ACM/IEEE
International Symposium on Modeling, Analysis and Simulation of Wireless and Mobile
Systems (MSWiM 2006) , Malaga, Spain, October 2006. PDF
S. ElRakabawy, C. Lindemann, and M. Vernon, Improving TCP
Performance for Multihop Wireless Networks, Proc.
International Conference on Dependable Systems and Networks (DSN 2005),
Yokohama, Japan, June 2005. PDF
S. ElRakabawy, A. Klemm, and C. Lindemann, TCP with Adaptive
Pacing for Multihop Wireless Networks, Proc. ACM
International Symposium on Mobile Ad Hoc Networking and
Computing (MobiHoc 2005) , Urbana-Champaign, IL, USA, May 2005.
PDF
|
|
Software
|
|
You can find the ns-2 simulation code here.
|
|
|
