الفهرس 
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Abstract
A mobile ad hoc network (MANEr) is a collection of mobile platforms or
nodes where each node is free to move about arbitrarily. Each node logically consists
of a router that may have multiple hosts and that also may have multiple wireless
communication devices. Ad hoc nodes should be able to detect the presence of other
nodes and to perform the necessary handshaking to allow communications and
sharing of information and services. A MANET is self-organizing, adaptive and
infrastructureless; this means that a formed network can be deformed on-the-fly
without the need for any system administration.
Numerous protocols have been developed for MANET. These protocols deal
with the typical limitations of these networks, which include high power
consumption, low bandwidth, and high error rates. The MANET routing protocols
may generally be categorized as: (a) table-driven, and (b) source-initiated on-demanddriven.
The Ad Hoc On-Demand Distance Vector (AODV) routing protocol is one of
the well-known and efficient on-demand MANET protocols. AODV currently does
not support Quality of Service (QoS) and also has no load balancing mechanism. The
QoS routing feature is important in a stand-alone multihop mobile network for realtime
applications and also for a mobile network to interconnect wired networks with
QoS support. The load balancing mechanism enables the protocol to choose routes in
such a way that the data traffic can be more evenly distributed in the network.
The thesis proposes some enhancements to the AODV protocol to provide
QoS and load balancing features by adding two extensions to the messages used
during route discovery.
The first extension (named QoS extension) specifies the service requirements
(maximum delay is chosen), which must be met by nodes rebroadcasting a Route
Request or returning a Route Reply for a destination. When a node needs a route to a
new destination with maximum delay requirements, it has to broadcast a new Route
Request message to find a route that satisfies the delay requirements. A node, which
receives such a request, must be able to meet the delay requirements in order to either
rebroadcast the Route Request (if it does not already have a route to the destinationor unicast a RREP to the source. A route can be determined when the Route Request
either reaches the destination with delay requirements satisfied, or reaches an
intermediate node with a valid route (satisfying delay requirements) to that
destination.
The second extension (named cost extension) is used to determine the
cumulative network load for a certain route in order to achieve load balancing. A node
receiving a route request would update the cost extension by adding to its value the
node’s average buffer usage. If several routes are available, that one with the
minimum cost (satisfying QoS requirements if any) will be chosen.
A detailed packet-layer simulation model with media access control (MAC)
and physical layer models is used to study the performance of both the AODV and the
QoS-AODV protocols. In this thesis, the ns-2 (network simulator version 2) has been
extended to include the proposed QoS-AODV protocol, so that the two protocols can
be compared accurately. Important performance measures such as average delay,
packet delivery fraction and normalized routing load are used in the comparison.
Simulations are presented for networks with 50 mobile nodes with different network
loads, delay constraints, topological rate of change and mobility speeds.
Simulation results show the efficiency of the proposed protocol especially in
satisfying load balancing and QoS requirements