01-03-2011, 09:35 AM
[attachment=9258]
A Bidirectional Routing Abstraction for Asymmetric Mobile Ad Hoc Networks
Abstract:
Wireless links are often asymmetric due to heterogeneity in the transmission power of devices, non-uniform environmental noise, and other signal propagation phenomenon. Unfortunately, routing protocols for mobile ad hoc networks typically work well only in bidirectional networks. This paper first presents a simulation study quantifying the impact of asymmetric links on network connectivity and routing performance. It then presents a framework called BRA that provides a bidirectional abstraction of the asymmetric network to routing protocols. BRA works by maintaining multi-hop reverse routes for unidirectional links and provides three new abilities:
improved connectivity by taking advantage of the unidirectional links, reverse route forwarding of control packets to enable off-the-shelf routing protocols, and detection packet loss on unidirectional links. Extensive simulations of AODV layered on BRA show that packet delivery increases substantially (two-fold in some instances) in asymmetric networks compared to regular AODV, which only routes on bidirectional links.
Existing System:
AODV avoids any unidirectional links in its paths. It achieves this by tracking the unidirectional links in a black list. Nodes discover unidirectional links and add them to the black list whenever an RREP sent along the reverse path fails to return an expected acknowledgment. Once added, a unidirectional page link is retained in the black list for a short lifetime. Nodes do not forward RREPs to any node in their black list.
Proposed System:
• Improved connectivity by taking advantage of the unidirectional links
• Reverse route forwarding of control packets to enable off-the-shelf routing protocols
• Detection packet loss on unidirectional links.
SYSTEM REQUIREMENTS:
Hardware Interface:
Hard disk : 40 GB
RAM : 512 MB
Processor : Pentium IV
Software Interface:
JDK 1.5
Swing Builder
SQL Server
