a study on the spectrum efficient multi-hop wireless network

adio is used for transmitting and receiving. And since the 802.11 MAC is naturally
unpredictable because of the collision avoidance, radio cannot be used for two
operations at the same time. This may stall the flow of the packets over multi-hop
wireless networks [12].
As the data flow from the source to the destination, the intermediate nodes will
update their timers associated with maintaining the route. For the case of AODV, the
routing table holds the current information:
- Destination.
- Next hop.
- Number of hops.
- Destination sequence number.
- Active neighbors for this route.
- Expiration time for this route table entry.
Expiration time is reset each time the route has been utilized using Eq. (2).
2.5 Active Route Timeout and Mobility
The Ad hoc On-Demand Distance Vector Routing Protocol (AODV) is a routing
protocol which is intended to be used in high mobile Ad-hoc networks. AODV is a
reactive protocol where the route discovery process is initiated only when it is needed.
MANET routing protocol plays an important role in the performance of the network. A
wide range of parameters controls the behavior of the routing protocol. One particular
parameter in AODV is the Route states hold time.
When the route is not used for some time, the nodes remove the route from its routing
table. The time until the nodes remove the route states is called the Active Route
Timeout (ART). In other words, ART is the time after the route is considered invalid.
In an Ad-hoc mobile network, the station movement speed is very crucial. The speed
has an effect on the throughput. Fig 2.4 is an example on how the mobility has an effect
on the connectivity between the stations. In a normal case, node C will have to
communicate with node A through node B. however, since node C is moving closer to A,
it can communicate directly to node A. This example illustrates only one case in which
the station movement could be an advantage in MANET [19].
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