Gugrajah_Yuvaan_ Ramesh_2003.pdf
Gugrajah_Yuvaan_ Ramesh_2003.pdf
Gugrajah_Yuvaan_ Ramesh_2003.pdf
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Introduction Chapter J<br />
The problems that face the development of ad hoc networks include limited power<br />
from portable power sources and the need for suitable power control algorithms, low<br />
bandwidth and high error rates from wireless channels, medium access control<br />
strategies, scheduling policies, security algorithms and routing protocols that can<br />
cope with the mobility and changes in topology. This dissertation focuses on routing<br />
in ad hoc networks.<br />
1.2. Routing in Ad Hoc Networks<br />
•<br />
The Mobile Ad Hoc Networking (MANET) [Man02] working group was created<br />
within the Internet Engineering Task Force (IETF) in the mid 1990s when mobile<br />
computing became popular and viable communications equipment based on radio<br />
frequency and infrared were developed. The key focus of the working group is to<br />
develop and evolve ad hoc network routing specifications for standardization. Due to<br />
the constantly changing topology and lack of central controller the routing protocol<br />
implemented needs to be distributed and dynamic, efficiently utilizing available<br />
resources and achieving fast route convergence.<br />
In current cellular networks, user mobility is handled by forwarding calls via the<br />
user's home network to the visited network. This forwarding principle also applies to<br />
Mobile IP [Perkins98]. A roaming user that enters a foreign network is associated<br />
with a visiting address provided by a foreign agent. The home agent establishes an<br />
Internet Protocol (IP) tunnel to the foreign agent using the provided visiting address.<br />
Any packet sent to the roaming user's home address is first sent to the home agent<br />
which redirects it to the foreign agent via the visiting address. This forwarding<br />
approach is only useful where only the nodes at the edges of fixed networks are<br />
mobile.<br />
In ad hoc networks this is not the case. Nodes at the centre of the network can also<br />
move, with the whole network being based on the idea that mobile devices behave<br />
both as routers and as hosts. Therefore, in an ad hoc network, mobility is handled by<br />
the routing algorithm, which needs to take care of changes in topology.<br />
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