2.5 Discussion
This chapter has surveyed the concepts of wireless ad hoc networks and the different types of
routing protocols related to it, Unicast and Multicast. This section aims to perform a
comparative discussion on those types of ad hoc routing protocols.
Table 2.1 Comparison between different kinds of unicast ad-hoc protocols.
Routing Class |
Proactive |
Reactive |
Hybrid |
Routing structure |
Flat and hierarchal are |
Mostly flat |
Mostly hierarchal |
Availability of |
Always available |
On-demand |
Depends on node location |
Periodic route |
Mostly used |
Rarely used, sometimes for local |
Usually |
Handling mobility |
Using periodical messages |
Different scenarios, AODV uses |
More than one path |
Storage |
High requirements |
Lower than proactive, depends on |
Depends on the size of the |
Delay |
Small as the routes are |
Bigger than proactive, need time |
Between proactive and |
Table 2.1 summarizes a comparison of the three categories of unicast protocols discussed in
this chapter, proactive, reactive and hybrid routing protocols. The tradeoffs between
proactive and reactive is quite complex. To decide which approach are better many factors
should be considered, such as the size of the network, the mobility, the traffic load and so on.
DSDV and OLSR discussed before are proactive routing protocols; which is suitable for
networks that topology change is small. This kind of protocols has an advantage that the
routes are immediately available and stored in tables which will reduce the response time. On
the other hand, they cause large amount of storage and high routing overhead as they use
periodical messages to keep information stored in nodes up to date. OLSR surpasses DSDV
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