01-11-2016, 03:49 PM
Study and Analysis of Throughput, Delay andPacket Delivery Ratio in MANET for Topology Based Routing Protocols (AODV, DSR and DSDV)
1463115197-StudyandAnalysisofThroughputDelayandPacketDeliveryRatioinMANETforTopologyBasedRoutingProtocolsAODVDSRandDSDV. (Size: 731.39 KB / Downloads: 8)
Abstract: Due to mobility constraints and high dynamics, routing in Mobile Ad-Hoc Network is a very challenging task. In this
work, we evaluate the performance of the routing protocols in mobile network environment. The objective of this work is to
assess the applicability of these protocols in different mobile traffic scenarios. Here we considered Topology based routing
protocols. In Topology-based routing protocols, both proactive (DSDV) and reactive protocols (AODV, DSR) have been
considered for the study. Performance metrics such as packet delivery ratio, throughput, and end-to-end delay are
evaluated using NS-2. Simulation results shows position based routing protocols gives better performance than topology based
routing protocols.
INTRODUCTION
Mobile Ad h o c Networks (MANET) has become an
exciting and important technology in recent years because
of the rapid proliferation of wireless devices. A mobile adhoc
network consists of mobile nodes that can move freely
in an open environment. Communicating nodes in a Mobile
Ad-hoc Network usually seek the help of other intermediate
nodes to establish communication channels. A Mobile Adhoc
Network is a group of wireless mobile computers
i n which nodes cooperate by forwarding packets for each
other to allow them to communicate beyond direct
wireless transmission range. Application such as military
exercises, disaster relief, and mine site operation may benefit
from ad-hoc networking, but secure and reliable
communication is a necessary prerequisite for such
applications.
The characteristics of these networks are summarized as
follows:
Communication via wireless means (Nodes can
perform the roles of both hosts and routers)
No centralized controller and infrastructure.
Intrinsic mutual trust.
Dynamic network topology.
Frequent routing updates.
1.1. Advantages and Applications
The following are the advantages of MANETs:
They provide access to information and
services
Regardless of geographic position.
These networks can be set up at any place and
time.
Some of the applications of MANETs are
Military or police exercises.
Disaster relief operations.
Mine cite operations.
Urgent Business meeting
2. MANET ROUTING PROTOCOLS
This section describes various routing protocols [2] that
have been chosen to simulate and analyze.
Topology based routing protocols
Topology based routing protocols [2] depend on the
information about existing links in the network and use them
to perform packet forwarding. The topology based routing
protocols can be further subdivided into proactive, reactive, and
hybrid protocols.
Proactive (table-driven) routing protocols [3-4] are similar to
the connectionless schemes of traditional datagram networks.
These protocols employ classical routing strategies such as
distance-vector (e.g. DSDV) or link-state (e.g. OLSR) routing
and any changes in the link connections are updated
periodically throughout the network. Proactive protocols
maintain routing information about the available paths in the
network even if these paths are not currently used. The main
disadvantage of these protocols is the maintenance of unused
paths may occupy an important part of the available bandwidth
if the network topology changes frequently. However, proactive
protocols may not always be suitable for highly mobile
networks such as MANETs.
Reactive (on-demand) routing protocols [3-4] ( e.g. AODV,
DSR) employ a lazy approach whereby mobile nodes only
discover routes to destinations on-demand. These protocols
maintain only the routes that are currently in use, thus reducing
the burden on the network when only a few of all available
routes is in use at any time. Reactive protocols often consume
less bandwidth than proactive protocols, but the delay in
determining a route can be substantially large. In reactive
protocols, since routes are only maintained while in use, it is
typically required to perform a route discovery process before
packets can be ex ch a n ged between nodes. Therefore, t h i s
l e a d s t o a d e l a y for the first packet to be transmitted.
Another disadvantage is that, although route maintenance is
limited to the routes currently in use, it may still generate a
significant amount of network traffic when the network
topology changes frequently. Finally, packets transmitted to the
destination are likely to be lost if the route to the destination
changes.
Hybrid routing protocol (ZRP)[3] combines both proactive
and reactive approaches to achieve a higher level of
efficiency and scalability.
However, even a combination of both approaches still needs to
maintain at least those network routes that are
currently in use. Therefore, limiting the amount of
topological changes, that can be tolerated within a given
amount of time. However, MANET differs from other
networks by its highly dynamic topology. Many simulation
result showed that most of the topology based routing
protocols suffer from highly dynamic nature of vehicular node
mobility because they tend to have poor route convergence and
low communication throughput. Position based routing
protocols has been identified as a more suitable routing
protocols for MANETs to give better performance and exhibit
scalability and robustness against frequent topological changes.
2.1.1 Destination Sequenced Distance Vector – DSDV
DSDV [3] is a hop –to –hop distance vector routing protocol.
In this protocol, each node has a routing table that stores
the next hop, number of hops for all the reachable destinations.
Each node broadcast routing updates periodically. The
advantage of DSDV over traditional distance vector routing
protocols is that DSDV guarantees loop-free routing.
2.1.2 Dynamic Source Routing (DSR)
DSR [3] allows the network to be completely selforganizing
and self-configuring, without the need for any
existing network infrastructure or administration. The
protocol is composed of the two main mechanisms of “Route
Discovery” and “Route Maintenance”, which work together to
allow nodes to discover and maintain routes to destinations in
the ad hoc network. An advantage of DSR is that nodes
can store multiple routes in their route cache, which
means that the source node can check its route cache for a valid
route before initiating route discovery and if a valid route is
found there is no need for route discovery.
2.1.3 Ad Hoc on Demand Distance Vector- AODV
The ad hoc on demand distance vector (AODV) [4] is based on
distance vector routing algorithm. However, unlike distance
vector, it is a reactive protocol i.e. it requests the route when
needed. It does not require nodes that maintain routes for
destinations, which a r e n ot a c t i ve l y used i n
communication. The features of AODV routing protocol are
loop-free routing and immediate notification is to be sent to
the affected nodes on link breakage. The algorithm uses
various messages to maintain and discover links. These are
route request (RREQ), route reply (RREP), and route error
(RERR).
When a source node desires to establish a communication
session, it initiates a path- discovery process. The s o u r c e n o d
e b ro a d c a sts a RREQ packet with its IP address, broadcast
ID (BrID) and sequence numbers of source and destination.
While the BrID and IP address is used to uniquely identify
each request. Receiving node set the backward pointer to the
source and generates a RREP packet if it is the
destination.
Route Table Management
The route table in AODV needs to keep track of the
following information:
Destination IP a ddr ess: - In this field IP
a ddr ess for destination node is stored.
Destination Sequence Number: - The sequence
number for the particular destination.
Next Hop: - The next neighbour of a particular node
in the direction of destination.
Hop Count: - Number of hops to the destination.
Active Neighbor List: - Neighbour nodes, which
are actively using this route entry.
2.1. Position based routing protocols
Position is one of the most important data for vehicles. In
MANET each vehicle wishes to know its own position as
well as its neighbor vehicle’s position. A routing protocol
using position information in known as the position based
routing protocol [5][7]. Position based routing protocols the
information about the physical location of participating
vehicles be available. This position can be obtained by
periodically transmitted control messages or beacons to the
direct neighbors. A sender can request the position of a
receiver by means of a location service. Position based
routing protocols are more suitable for MANETs since the
Mobiles nodes are known to move along established paths.
Since routing tables are not used in these protocols
therefore no overhead is incurred when tracing a route.
In MANETs, route is composed of several pair of mobiles
nodes (communication links) connected to each other from the
source to the destination. If we know the current information of
node involved in the routes, we can predict their positions [6]
in the near future to predict the l i n k bet ween ea ch pa i r
of nodes in the path. MANET is a self- organizing mobile ad -
hoc network in which to acquire the position information of
neighbouring nodes, each node periodically exchanges a list of
all neighbours it can reach in one hop, using a HELLO
control message or a beacon that contains its ID, location,
speed, and a timestamp.
CONCLUSIONS
In this paper we find out the performance of three
topology based routing protocols (both reactive and
proactive) like DSDV, AODV and DSR by
increasing numbers of nodes. Here, we find out the
performance on the basis of throughput, delay and packet
delivery ratio. By comparing these protocols on the basis
of various performance metrics we have reached to a
conclusion that reactive topology based protocols are
better than proactive topology based routing protocols.