International Journal of Engineering Trends and Technology- Volume3Issue4- 2012
Performance Analysis of Weighted Load balanced
routing Protocol with Ad hoc on-demand Distance
Vector
R.Madhanmohan, K.Selvakumar
Department of Computer Science & Engineering, Annamalai University
Annamalai nagar , India
Abstract— This Paper describes about WLBR(Weighted Load
Balanced Routing Protocol) and its performances are analyzed
with AODV[1].The simulation results shows that this proposed
protocol outperforms well than the AODV. The main
performance metrics used here are throughput, node remaining
energy, packet delivery ratio, energy consumed and routing
delay.
Keywords— WLBR, AODV, Load balancing, modified AODV,
Route energy, Aggregate interface queue length.
I. INTRODUCTION
A mobile ad hoc network is defined as 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 . The routing protocols in
MANET can be categorized in to three different groups:
Global/Proactive, On-demand/Reactive and Hybrid routing
protocols . In global routing protocols, each node stores and
maintains routing information to every other node in the
network. In on-demand routing protocols, routes are created
when required by the source node, rather than storing up-todate routing tables. Hybrid routing protocols combine the
basic properties of the two classes of protocols mentioned
earlier. In practice, some routes get congested, while other
routes remain underutilized. This results in poor performance
of mobile ad hoc networks. Therefore, the need for balancing
the load distribution among various routes becomes more
important.
The aim of this work is to provide a characteristic
comparison for a number of proposed load balanced ad hoc
routing protocols and to propose an effective approach
towards load balanced routing. I evaluated the performance of
proposed routing protocol and compare it with AODV routing
protocol using performance metrics like Throughput, packet
Loss, packet delivered, energy consumption, packet-delivery
ratio.. We perform this study using ns-2.34 as the simulation
tool. The simulation study reveals that modified AODV
performs better than AODV by reducing normalized routing
load.
II. AODV ROUTING PROTOCOL
An Ad hoc On-demand Distance Vector (AODV)
routing protocol is an on-demand protocol that is it discovers
routes on an as needed basis using route discovery process. It
uses traditional routing tables, one entry per destination to
maintain routing information.
When a route to a new destination is needed, the
node broadcasts a RREQ to find a route to the destination. A
route can be determined when the RREQ reaches either the
destination itself, or an intermediate node with a 'fresh
enough' route to the destination. A 'fresh enough' route is a
valid route entry for the destination whose associated
sequence number is at least as great as that contained in the
RREQ. AODV uses sequence numbers maintained at each
destination to determine freshness of routing information and
to prevent routing loops. These sequence numbers are carried
by all routing packets. The route is made available by unicasting a RREP back to the origination of the RREQ. AODV
relies on routing table entries to propagate a RREP back to the
source and subsequently, to route data packets to the
destination. An important feature of AODV is maintenance of
timer based states in each node, regarding utilization of
individual routing table entries[2].
A routing table entry is expired if not used recently.
A set of predecessor nodes is maintained for each routing
table entry, indicating the set of neighbouring nodes that use
that entry to route data packets. These nodes are notified with
RERR packets when the next hop link breaks. Each
predecessor node, in turn, forwards the RERR to its own set of
predecessors, thus effectively erasing all routes using the
broken link[3].
AODV uses the following fields with each route table entry:
- Destination IP Address
- Destination Sequence Number
- Valid Destination Sequence Number flag
- Other state and routing flags (e.g., valid, invalid,
repairable, being repaired)
- Network Interface
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International Journal of Engineering Trends and Technology- Volume3Issue4- 2012
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Hop Count (number of hops needed to reach destination) destination node finds a suitable path, a RREP packet is sent
Next Hop
back towards the source node.
List of Precursors (described in Section 6.2)
Lifetime (expiration or deletion time of the route)
The detailed process is shown in Algorithm 1.
Managing the sequence number is crucial to avoiding routing Algorithm 1 [Route discovery process].
loops, even when links break and a node is no longer Source node Ns wants to find a path to destination node Nd.
reachable to supply its own information about its sequence Suppose that z is the number of mobile nodes and N is the set
number. A destination becomes unreachable when a link of mobile nodes, i.e., N = {N1, N2, . . . , Nz}, where Ns, Ni,
breaks or is deactivated. When these conditions occur, the Nd ε N, 1 ≤ s, d, i ≤ z and s ≠ d.
route is invalidated by operations involving the sequence Assuming that node Ni is an intermediate node that receives
number and marking the route table entry state as invalid.
the RREQ packet.
easy way to comply with the conference paper formatting
requirements is to use this document as a template and simply
if (node Ni is the destination node Nd)
type your text into it.
{
1. Destination node Nd analyzes route energy
III. PROPOSED PROTOCOL
(RE), aggregate interface queue length
(AIQL), and hop count (HC) along each
The aim of the protocol (WLBR)[4] proposed in this
feasible path.
paper is to distribute the traffic in MANETs by using the
2. Destination node Nd calculates weight
information available in the network. The basic idea is to
values of each feasible path and selects the
select a routing path that consists of nodes with higher energy
route with maximum weight value as
and hence longer life in order to reduce the routing overhead
primary routing path.
and end-to-end delay by distributing the packets over the path
3. Destination node then sends a RREP packet
which is less utilized.
to source node Ns.
Before introducing the proposed routing protocol algorithm, I
4. Source node Ns starts sending the data.
first define the route determining parameters, as follows:
}
else
1. Route Energy (RE): The route energy is the sum of energy
Node Ni forwards the RREQ packet to the
possessed by nodes falling on a route. Higher the route energy,
lesser is the probability of route failure due to exhausted nodes. neighbouring node.
2. Aggregate Interface Queue Length (AIQL): The sum of
interface queue lengths of all the intermediate nodes from the
source node to the current node.
3. Hop count (HC): The HC is the number of hops for a
feasible path.
A. Route Discovery
The route discovery procedure is similar to that of
Ad hoc On-demand Distance Vector (AODV) routing
protocol. A source node initiates the route discovery process
whenever it wants to communicate with another node for
which it has no routing information in its table. The source
node initiates route discovery by broadcasting a route request
(RREQ) packet to its neighbouring nodes. When a node
receives a RREQ, it checks its routing table for a route to the
destination node[5]. If routing table contains a route to the
destination node, its sequence number is checked to determine
whether it is at least as great as that contained in the RREQ
packet. If the two conditions are satisfied, then the
intermediate node sends a route response along the reverse
path back to the source node. Otherwise, the node increments
the hop count by one, adds its own interface queue length and
energy and rebroadcasts the route discovery packet. When the
B. Route Selection
When destination node D receives a RREQ packet, it
waits for a certain amount of time to receive other RREQ
packets. It then computes the weight value for each route.
Route weight computation
The path selection[6] and traffic distribution is based
upon three factors: the route energy, the aggregate interface
queue length and the hop count. Route energy is taken as a
factor keeping in view that MANETs have scarce energy
resources. Using a route frequently while other routes are idle
or under loaded may result in network instability. The
aggregate interface queue length gives us the idea about how
busy our route is. Its higher value depicts higher load on the
route. Thus this parameter helps in determining the heavily
loaded route.
If each intermediate host has a large roaming area, and the
MANET has many nodes (and hops), then a feasible path with
a low hop count is preferred and hence the metric hop count
has been considered for route selection. Our protocol
effectively combines all the parameters with weighing factors.
The values of these factors can be chosen as per the
requirements.
C. Route Maintenance
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International Journal of Engineering Trends and Technology- Volume3Issue4- 2012
Due to the high mobility of nodes in MANETs, links
break easily. Route maintenance is initiated when the route is
active and data packets are transmitting. A link failure occurs
when a mobile node moves out of another mobile node’s radio
transmission range. The mobile node that discovers the link
failure broadcasts a RERR packet to other mobile nodes. On
receiving a RERR packet, the source node initiates a new
route discovery or finds an alternative path for routing
The detailed process is shown in Algorithm[7] 2.
Algorithm 2 [Route maintenance process]. Assume that
source node Ns wants to find a path to destination node Nd.
Suppose that z is the total number of mobile nodes and N is
the set of mobile nodes, N ={N1, N2, . . . , Nz}, where Ns, Ni,
Nd ε N, 1 ≤ s, d, i ≤ z and s ≠ d. In addition, we assume that
the link between node Ni and node Nj is broken.
if (node Ni detects the link failure to the next node)
{
1. Node Ni sends the error packet.
2. Node Ns receives the error packet.
3. Node Ns stops sending the data.
4. Node Ns restarts the route discovery process or
finds an alternative path for routing.
}
else Node Ni continues to send the data.



Routing delay refers to the length of time required to
move a packet from source to destination through the
internet.
Packet Delivery ratio can be calculated as the ratio
between the number of data packets that are sent by
the source and the number of data packets that are
received by the sink.
Energy consumed refers to the amount of energy
spent while transmitting data packets from source to
sink.
The results are plotted as graphs, each graph shows a
comparison between the performance of the AODV and
modified AODV on various parameters like throughput,
routing delay, packet delivery ratio, packet loss , packet
received and energy consumed.
The graphs shows 6 curves (3 for AODV and 3 for modified
AODV) . Each curve represents the values for a source and
sink pair
IV. SIMULATION ENVIRONMENT AND PERFORMANCE
COMPARISON
We have used ns-2.34 for simulations. The
performance comparison study with AODV and the modified
AODV is carried.12 source nodes are used for this simulation,
each node transmitting packets at the rate of four packets per
second, with a packet size of 512 bytes. A movement scenario
arranges the movement and the position of the nodes
according to the random waypoint model.
The other parameters used in the simulation of
Mobile Ad Hoc Network are
 Channel type – Wireless Channel
 Radio-propagation model – Two RayGround
 Network interface type -Wireless
 MAC type - 802.11
 Interface queue type – priority queue
 Link layer type - LL
 Antenna model – Omni Antenna Model
 Max packet in queue - 50
 Number of mobile nodes - 50
 X dimension of topography - 1000
 Y dimension of topography - 1000
Fig 3. Throughput comparison between AODV and
modified AODV
Graph details
X- axis – Time
Y-axis – Throughput.
Maximum Throughput for AODV – 9.00, 9.00, 9.00
respectively for each source sink pair.
Maximum Throughput for modified AODV – 12.00, 15.00,
21.00 respectively for each source sink pair.
From the above graph it is very clear that modified
AODV is exhibiting higher throughput in all the cases.
Performance Metrics:

Throughput - It is 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.
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International Journal of Engineering Trends and Technology- Volume3Issue4- 2012
losses are quite high in AODV which is most important
drawback in AODV.
Fig 4. Routing Delay comparison between AODV and
modified AODV
Graph details
X- axis – Time
Y-axis – Routing Delay
The above graph shows that routing delay in both the routing
delay almost equal to each other. Since the traffic scenario
used in this experiments are normal loads there is no much
difference in the routing delay. If the number of node is
increased then surely the modified AODV will have less
routing delay.
Fig 6. Packet Loss comparison between AODV and
modified AODV
X- axis - Time
Y –axis – Packet Loss
The above graph shows that the packet loss during the data
transfer between source 2 and sink 2 pair is high. This high
loss may be due to high traffic in the network. Since packet
loss is high it will lead a throughput reduction in the network.
Fig 5. Packet Delivery Ratio comparison between AODV
and modified AODV
X-axis – Time
Y-axis – PDR
The modified AODV is showing high PDR ranging above
18.00 in the data transfer between source 1 and sink 1 pair.
Since the AODV is having less PDR it shows the packet
Fig 7. Packet received comparison between AODV and
modified AODV
X- axis – Time
Y- axis – Packets Received.
As inferred from the previous graph, the number of packets
received for the source sink pair 2 is very low. This shows that
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International Journal of Engineering Trends and Technology- Volume3Issue4- 2012
results are very accurate and calculations are done without any
mistake.
feasible paths. There are three parameters in mod-AODV that
are used to calculate the weight of the feasible path: the
aggregate interface queue length, the route energy, and the
hop count. Route selection is based on the weight value of
each feasible path. In a feasible path, the higher the weight
value, the higher is its suitability for traffic distribution.
Simulation results show that the proposed AODV outperforms
AODV especially in an environment with moderate mobility.
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Fig 8. Energy Consumption comparison between AODV
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V.
CONCLUSION
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