Gugrajah_Yuvaan_ Ramesh_2003.pdf
Gugrajah_Yuvaan_ Ramesh_2003.pdf
Gugrajah_Yuvaan_ Ramesh_2003.pdf
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Routing Protocols for Ad Hoc Networks Chapter 2<br />
The imprecise knowledge of the best path to a distance destination is compensated by<br />
the fact the route becomes progressively more accurate as the packet gets closer to<br />
the destination.<br />
FSR is based on Global State Routing (GSR) [Gerla98]. GSR can be considered a<br />
special case of FSR where there is only one fisheye scope level. Although<br />
information is still only exchanged between direct neighbours, the overhead is high<br />
in GSR because the entire topology table is exchanged among neighbours. Unlike<br />
FSR, GSR does not distinguish between nodes based on their relative distance away<br />
from the node in question. FSR was designed to be able to scale to large networks,<br />
but avoid on-demand techniques while keeping overhead low and still provide<br />
adequate routes which become more accurate closer to the destination.<br />
2.2:6.3.<br />
CGSR<br />
Figure 2-9. Fisheye scope in FSR.<br />
• Centre node<br />
-0 I-hop scope<br />
• 2-hop scope<br />
• > 2-hop scope<br />
Cluster-head Gateway Switch Routing (CGSR) [Chiang97] aggregates nodes into<br />
clusters. Each cluster is controlled by a cluster-head and adjacent clusters<br />
communicate via gateway nodes, which are members of two or more clusters. A<br />
node is always within transmission range of the cluster-head of its cluster. The<br />
cluster-head selection process is determined by the Least-Cluster-head Change<br />
2-27
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