22-09-2012, 02:51 PM
Effects of Packet Size on AODV Routing Protocol Implementation in
Homogeneous and Heterogeneous MANET
1Effects of Packet.pdf (Size: 738.79 KB / Downloads: 42)
Abstract
Networks are being used in various areas and the
demand of users nowadays has motivated the emergence of the
Mobile Ad Hoc Network (MANET). MANET is a dynamic
network without fixed infrastructure due to their wireless
nature and can be deployed as multi-hop packet networks. It is
a wireless network and has dynamic topology due to its node
mobility. There are two types of MANET, homogeneous and
heterogeneous MANET. An architecture has been designed in
previous work to model these two types of MANET. Three
scenarios have been defined from this architecture: scenario I
(communication entirely within MANET; homogeneous
MANET), scenario II (communication between MANET and
wireless LAN; heterogeneous MANET) and scenario III
(communication between MANET with wireless LAN and
wired LAN; heterogeneous MANET). MANET has its own
routing protocols which can compromised with frequent route
exchange, dynamic topology, bandwidth constraint and multihop
routing. Ad hoc On Demand Distance Vector (AODV) is
one of the routing protocols in MANET
INTRODUCTION
MANET is a group of wireless computing devices like
laptop, mobile phone, Personal Digital Assistant (PDA), or
similar devices which can communicate directly with one
another without a central coordinator. A MANET is an
autonomous system of mobile routers and associated hosts
connected by wireless links. It does not require a fixed
network infrastructure due to its wireless nature and can be
deployed as a multi-hop packet network both rapidly and
with low expense [1]. MANET has its own routing
protocols which can be compromised with frequent route
exchange, dynamic topology, bandwidth constraint and
multi-hop routing. An ad hoc routing protocol is a
convention, or standard, that controls how nodes decide
which way to route packets between computing devices in a
mobile ad hoc network [2]. The routing protocols that are
available for MANET comprise proactive (table driven),
reactive (on demand) and hybrid routing protocols.
Node Communication between MANET and
Wireless Network
Nodes in MANET communicate with a WLAN node
via WAP and communicate with cellular phones via CBS.
MANET uses a multi-hop ad hoc routing protocol which
can extend the access point range. This means nodes that are
not directly covered by an access point get connected
through other nodes by multi-hop operations. Cellular base
stations in contrast have a wide coverage area and they will
enable the communication between MANET and the
cellular networks. A cellular network enhances the
performance of MANET since it can control the operation
of MANET by providing authentication, routing and
security.
OMNET++ SIMULATION
Objective Modular Network Testbed in C++
(OMNeT++) is a component based, modular and open
architecture discrete event network simulator which can run
on all common platforms including Linux, Mac OS/X and
Windows using GCC tool chain or Microsoft Visual C++
compiler. It was released in 1992 and publicly available
since 1997 [7]. Although OMNeT++ was designed to be as
general as possible, it is commonly used in simulation of
computer network and queuing network.
Performance Metrics
Performance metrics are high-level measures used to assess
the overall performance of the network. It should be
constructed to encourage performance improvement,
effectiveness and efficiency. There are several metrics
always considered to measure the performance of a network,
for example throughput, end-to-end delay, jitter and packet
delivery ratio. As for the experiments which had been
carried out, the simulation used throughput and packet
delivery ratio (PDR) as the metrics.
Throughput: Throughput is one of the dimensional
parameters of the network which indicates the fraction of
the channel capacity used for useful transmission selection
of a destination at the beginning of the simulation i.e.,
information whether data packets were correctly delivered
or not [8]. Furthermore, many MANET applications benefit
from increased throughput [9]. Throughput is defined as the
average rate of successful message delivery over a
communication channel. This data may be delivered over a
physical or logical link, or pass through a certain network
node [10].
FUTURE WORKS
This work limits the number of nodes involved since it
uses the scenarios derived from the HetMAN architecture.
In the future, this work will tend to increase the number of
nodes so as to measure the performance of AODV in large
scale heterogeneous network. The future works could
involve the comparison of the AODV routing protocol with
other routing protocols like DSR, DSDV, OLSR or ZRP in
heterogeneous MANET.
Overall, this research shows that the performance of the
AODV routing protocol in homogeneous MANET is better
compared to heterogeneous MANET. These tests prove that
the current AODV routing protocol is less adaptable in a
wireless heterogeneous MANET environment. Studies of
the performance of the AODV routing protocol can lead to
the development of an optimal enhanced AODV protocol
which can maximize routing performance, particularly in
heterogeneous networks and overcome the limitation of the
existing AODV protocol. It is possible to expand the
implementation of HetMAN architecture especially to
consider a cellular network in the work.
CONCLUSION
In this paper, we assessed the performance of AODV
routing protocol for different packet size in homogeneous
and heterogeneous MANET through the OMNeT++
simulation. In the simulation, the size of the packets
transmit has a large impact on throughput and PDR in
wireless environment. Overall, the result shows as the size
of packet size increase, the throughput and PDR also will
increase except for certain circumstances when the size of
packets achieve certain limits as the large packet size keeps
the transport layer channel busy and it affected the value.
The result for scenario I had 13% higher throughput value
compared to scenario II and, 33% higher throughput
compared to scenario III. Scenario I had 25% higher PDR
than scenario II and 45% higher PDR than scenario III.
Hence, we can conclude that the performance of the AODV
routing protocol in homogeneous MANET is better
compared to heterogeneous MANET.