Extension of Optimized Linked State Routing Protocol For Energy Efficient Applications

International Journal on AdHoc Networking Systems (IJANS) Vol. 1, No. 2, October 2011
DOI : 10.5121/ijans.2011.1203 23
EXTENSION OF OPTIMIZED LINKED STATE
ROUTING PROTOCOL FOR ENERGY EFFICIENT
APPLICATIONS
Mayur Tokekar1
and Radhika D. Joshi2
1
Department of Electronics and Tele-communication, College of Engineering, Pune,
India
mayurtokekar@gmail.com
2
Department of Electronics and Tele-communication, College of Engineering, Pune,
India
rdj.extc@coep.ac.in
ABSTRACT
Mobile Ad-hoc network (MANET) is infrastructure less network in which nodes are mobile, self
reconfigurable, battery powered. As nodes in MANET are battery powered, energy saving is an important
issue. We are using routing protocol to save energy so as to extend network lifetime. We have extended
original Optimized Linked State Routing (OLSR) protocol by using two algorithms and named it as
Enhancement in OLSR using Residual Energy approach (EOLSR-RE) and Enhancement in OLSR using
Energy Consumption approach (EOLSR-EC). To analyze relative performance of modified protocol
EOLSR-RE and EOLSR-EC over OLSR, we performed various trials using Qualnet simulator. The
performance of these routing protocols is analyzed in terms of energy consumption, control overheads, end
to end delay, packet delivery ratio. The modified OLSR protocol improves energy efficiency of network by
reducing 20 % energy consumption and 50% control overheads.
KEYWORDS
MANET, OLSR, EOLSR-RE, EOLSR-EC, QoS parameters.
1. INTRODUCTION
Ad-hoc network is one of the emerging trends in wireless communication. In conventional
wireless communication there is need of base station for communication between two nodes.
These base station leads to more infrastructure and more cost. An ad hoc network facilitates
communication between nodes without the existence of an established infrastructure. Nodes are
connected randomly using ad-hoc networking and routing among the nodes is done by forwarding
packets from one to another which is decided dynamically. In general, MANET’s are formed
dynamically by an autonomous system of mobile nodes that are connected via wireless links
without using any centralized administration [1]. Mobile nodes that are within each other’s radio
range communicate directly via wireless links, while those that are far apart rely on other nodes to
relay messages as routers. Node mobility in an ad hoc network causes frequent changes of the
network topology. The scopes of the ad-hoc network are also associated with dynamic topology
changes, bandwidth-constrained, energy constrained operation, limited physical security,
mobility-induced packet losses, limited wireless transmission range, broadcast nature of the
wireless medium, hidden terminal problem, packet losses due to transmission errors [2].

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In Energy constrained operations, it is important to save energy which results in improvement in
network lifetime. For example, in battle fields soldiers are unable to charge node batteries so
there is need for them to save battery power in such a way that communication can be possible for
longer time. To improve network lifetime there are different methodologies used at different
layers of OSI model. Network layer is used for routing of packets from source to destination.
There are number of routing protocols defined in MANET, for example DSDV, AODV, DSR,
OLSR, ZRP etc. The main objective is to design routing protocol in such a way that it works
effectively in energy constrained applications. The main focus is on OLSR routing protocol
modification in network layer.
The paper is organized as follows. Section II explains different types of routing protocols. Section
III discusses the basics of OLSR protocol and study of related energy aware techniques. Section
IV discusses the proposed modification in OLSR. Section V represents the simulation details and
QoS parameters. Section VI discusses results obtained by Qualnet simulator. Finally section VII
concludes the paper with future work in section VIII.
2. CLASSIFICATION OF ROUTING PROTOCOL
In MANET, each node between source and destination acts as routers. The routing of data
packets from source to destination are controlled by different routing protocols. Different routing
protocols are classified as shown in Figure;
Figure 1.Classification of Routing Protocols
2.1. Proactive routing protocols
In proactive routing, each node has one or more tables that contain the latest information of the
routes to any node in the network. Each node maintain routing tables and respond to the changes
in the network topology by propagating updates throughout the network in order to maintain a
consistent view of the network. Many proactive routing protocols have been proposed, for e.g.
Destination Sequence Distance Vector (DSDV), Optimized Linked State Routing (OLSR) and so
on.
2.2. Reactive protocols
Reactive routing protocols take a lazy approach to routing. They do not maintain or constantly
update their route tables with the latest route topology. This type of routing creates routes only
when desired by the source node. The source node initiates a process called route discovery when
it requires a route to the destination. This process is completed when a route is found or when all
the possible routes are examined. The process of route maintenance is carried out to maintain the
established routes until either the destination becomes unavailable or when the route is no longer
required.Several reactive protocols have been proposed such as Dynamic Source Routing
protocol (DSR), Ad hoc On-demand Distance Vector (AODV), Temporary Ordered Routing
Algorithm (TORA), and so on.

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2.3. Hybrid routing protocols
This type of protocol is combination of table-driven (Proactive) and on demand (Reactive)
routing protocol i.e. it contains features of proactive as well as reactive protocol.Several hybrids
routing protocols have been proposed such as Zone Routing Protocol (ZRP), Zone-based
Hierarchical Link State (ZHLS) and so on, but the most popular protocol is ZRP.
3. OLSR OVERVIEW AND RELATED WORK
OLSR [3] is proactive in nature, having routes immediately available in each node for all
destinations in the network. OLSR is an optimization of pure link state routing protocol like Open
Shortest Path First (OSPF) [4]. This optimization is related to concept of multipoint relay (MPR).
A multipoint relay reduces the size of control messages. The use of MPRs also minimizes
flooding of control traffic. Multipoint relays forward control messages, providing advantage of
reduction in number of retransmissions of broadcast control messages. OLSR contains two types
of control messages: neighborhood and topology messages, known as Hello messages and
Topology Control (TC) messages. OLSR provides two main functionalities: Neighbor Discovery
and Topology Dissemination. With the help of these two functionalities, each node computes
routes to all known destinations.
Figure 2.Selection of MPR and Broadcasting TC packets
3.1. Neighbor Discovery
Each node periodically broadcasts Hello messages, containing list of neighbors known to node
and link status. The link status can be either symmetric or asymmetric, multipoint relay, or lost
link. The Hello messages are received by all one-hop neighbors and not forwarded. Hello
messages discover one-hop neighbors as well as its two-hop neighbors. Hello messages are
broadcast at regular interval (Hello_interval). The neighborhood and two hop neighborhood
information has holding time (Neighbor_hold_time), after which it is not valid. With the help of
this information node selects its own set of MPRs among one-hop neighbors. Multipoint relays
computed whenever there is change in one-hop neighborhood and two-hop neighborhood. MPR
is one-hop neighbors with symmetric link, such that all two-hop neighbors has symmetric link
with multipoint relays. Figure 2 shows selection of MPR node using HELLO packets. Node is
selected as MPR node when it has willingness high i.e. W_HIGH or default i.e. W_DEFAULT
otherwise rejected.
3.2. Topology Dissemination
Each node of the network maintains topological information about the network obtained with
help of TC messages. Each node selected as MPR, broadcasts TC message at regular interval

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(TC_interval). The TC message originated from node which declares MPR selectors of that node.
If change occurs in MPR selector set, then TC message can be sent earlier than pre-specified
interval. The TC messages are sent to all nodes in the network by taking advantage of MPR nodes
to avoid number of retransmissions. Thus, a node is reachable directly or via its MPRs. The
topological information collected in each node has holding time (Top_hold_time), after which
information is not valid. Figure 2 shows broadcasting of TC message with the help of MPR
nodes.
3.3. Route Calculation
The neighbor information and the topology information are refreshed periodically, and they
enable each node to compute the routes to all known destinations. These routes are computed
with Dijkstra’s shortest path algorithm [5]. Hence, they are optimal with respect to the number of
hops. Moreover, for any route, any intermediate node on this route is a MPR of the next node.
The routing table is computed whenever there is a change in neighborhood or topology
information.
3.4. HELLO and TC packet format
Reserved Htime Willingness
Link Code Reserved Link Message size
Neighbor Interface Address
Neighbor Interface Address
Figure 3.OLSR HELLO Packet Format Figure 4.OLSR TC Packet Format
Figure 3 shows HELLO packet format for OLSR. The Reserved portion in HELLO packets is
used for further modification. Htime specifies time before transmission of next HELLO packet.
Willingness entry specifies node willingness to forward traffic. Link Code gives the information
about link between sender node and neighbor node. It represents status of neighbor node.
Neighbor interface address denotes address of interface of neighbor node. Link Message size
gives total length of link messege.
Figure 4 represents TC packet format for OLSR. Advertised Neighbor Sequence Number (ANSN)
which increments sequence number whenever there is change in neighbor set. Reserved field is
used for further modification in TC packets. Advertised Neighbor Main Address field contains
main address of neighbor node.
3.5. Study of Energy Efficient Routing Schemes
There are various ways to save energy from physical layer to application layer. In network layer
energy saving can be possible by selecting energy efficient path for sending data from source to
destination. The surveys of different energy saving techniques are discussed as below;
I. Stojmenovic and X. Lin [6] proposed localized power aware routing algorithms which are
devised on the assumption that each network node has accurate information about the location of
its neighbors and the destination node. Nodes exchange location information via control
messages.
Three algorithms are proposed in [6]:
• Power-efficient routing: Each node decides to forward packets that are intended for a
certain destination to a neighbor based on the minimum transmission power between this
sending node and its neighbors.
ANSN Reserved
Advertised Neighbor Main Address
Advertised Neighbor Main Address
..............

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• Cost-efficient routing: The node chooses the neighbor to send to, if the destination is not
within reach, based on a cost function that can consist, for example, the sum of the cost of
sending node to this neighbor plus the estimated cost of the route from the neighbor up to
the destination. This latter part of the cost is assumed to be proportional to the number of
hops in between.
• Power-cost efficient routing algorithms: Uses a combination of the two above metrics, in
the form of either the product or the sum of these metrics.
C.K.Toh [7] explains MTPR (Minimum Total Transmission Power Routing) mechanism, where
route having minimum transmission power is selected. The information of total energy
consumption is provided along route using HELLO and TC packets in OLSR. Based on this
information route is selected for sending data to destination.
CMMBCR (Conditional Max Min Battery Capacity Routing) [18] mechanism considers both the
total transmission energy consumption of routes and the remaining power of nodes. When all
nodes in some possible routes have sufficient remaining battery capacity, i.e. above a threshold,
route with minimum total transmission power among the routes is chosen. Since less total power
is required to forward packets for each connection, the load for most of the nodes must be
reduced, and their by lifetime will be extended. But, if all routes have nodes with low battery
capacity i.e. below the defined threshold, a route including nodes with lowest battery capacity
must be avoided to extend the lifetime of these nodes.
Energy efficient technique for selection of MPR nodes is proposed by Saoucene Mahfoudh and
Pascale Minet [8] where node considers residual energy for selection of MPR. The node having
minimum residual energy is not selected as MPR. There are three policies are considered for
selection of MPR.
• E: considers only residual energy of node itself.
• M1E: considers weighted residual energy of node itself and 1-hop neighbors.
• M2E: M2E considers weighted residual energy of node, 1-hop and 2-hop neighbors.
Minimum Drain Rate (MDR) mechanism is proposed for selection of path having maximum
lifetime value in [9]. MDR mechanism calculates cost function which takes into account the
drain rate index and residual battery power. Maximum lifetime value of a given path is
determined by minimum cost value over the path. From the set routes, the route having highest
maximum lifetime is selected for transmission.
The J. H. Chang and L. Tassiulas [10] proposed two algorithms with the aim of extending the
network lifetime via optimizing the routing from an energy consumption perspective.
1. Flow augmentation (FA) algorithm: is based on creating a link cost function. This
function considers the following parameters: energy cost for unit flow over the link, the
initial energy and the remaining energy at the transmitting node. A good candidate for the
selected path should consume less energy and should avoid nodes with low remaining
energy.
2. Flow redirection (FR) algorithm: If we have multiple sources and destinations, then under
the optimal flow (i.e. minimum lifetime over all nodes is maximized) the minimum
lifetime of every path from the source to the destination is the same. The minimum
lifetime of this set of paths can be increased by redirecting an arbitrarily small amount of
flow to the paths whose lifetime is longer than these paths such that the minimum lifetime
of the latter path after the redirection is still longer than the system lifetime before the
redirection.

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4. PROPOSED IDEA
In this section, the modification steps for OLSR protocol are discussed. The modified protocol is
named as EOLSR. The OLSR protocol is modified in two processes i.e. while selecting MPR
nodes and while calculating route for forwarding data.
4.1. MPR Selection
The existing OLSR consumes more energy in energy constrained applications which results in
less network lifetime. To improve network lifetime as well as energy efficiency OLSR is
modified by using two approaches as below;
1. By setting threshold for Residual Energy
2. By setting threshold for Energy Consumption
For MPR selection we have decided a threshold value, which is one third of initial energy for
both residual energy and energy consumption approach.
• If the residual energy of node is less than threshold value then node having LOW-MPR-
WILL while residual energy of node is greater than threshold value than node having
HIGH-MPR-WILL.
• If the energy consumed by node is less than threshold value then node having HIGH-
MPR-WILL while residual energy of node is greater than threshold value than node
having LOW-MPR-WILL.
4.1. New HELLO and TC packet format
Residual Energy Htime Willingness
Link
Code
Reserved Link message size
Neighbour Interface Address
Energy
Consumption
Htime Willingness
LinkCode Reserved Link message size
Figure 5.EOLSR-RE HELLO Packet
Format
Figure 6.EOLSR-EC HELLO Packet
Format
ANSN Residual Energy
Advertised Neighbour Main Address
..............
ANSN Energy Consumption
..............
Figure 7.EOLSR-RE TC Packet Format Figure 8.EOLSR-EC TC Packet Format
HELLO packets are used for selection of MPR nodes. For selection of MPR each node having,
• Highest residual energy
• Lowest energy consumption
There is need to update residual energy of each node at regular interval. For this purpose the
value of residual energy and energy consumed by node is included in HELLO packet as shown

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in Figure 5 and Figure 6 respectively. The reserved part in OLSR HELLO packet format as
shown in Figure 3 is assigned to residual energy in EOLSR-RE and energy consumption in
EOLSR-EC. Each node sends HELLO packet with entry for current residual energy and
depending on threshold value set it selects MPR node.
The reserved part in TC packet as shown in Figure 4 is modified with entry for residual energy
and energy consumption of node as shown in Figure 7 and Figure 8 respectively. The TC packets
are forwarded to entire network with the help of MPR nodes. The TC packets are used to
disseminate topology information over entire network. The modified TC packet format distributes
residual energy of each node and energy consumed by each node over entire network. After
knowing topology information for each node in network the route calculation is performed.
4.2. Steps for Modifications
1. Remove all entries from MPR table.
2. Selection of MPR
• Residual Energy Approach
a) Send HELLO packets with energy (residual energy) and willingness entries.
Willingness is obtained by setting threshold value for residual energy.
b) Select MPR nodes using willingness of that node in the network.
• Energy Consumption Approach
a) Send HELLO packets with energy (energy consumption of node) and willingness
entries. Willingness is obtained by setting threshold value for energy
consumption.
b) Select MPR nodes using willingness of that node in the network.
2. If willingness of the node is HIGH then it is selected as MPR otherwise rejected.
3. After fixing MPR nodes TC packets are transmitted or broadcasted in the network. Only
MPR nodes can retransmit or broadcast TC packets, other nodes cannot retransmit or
broadcast TC packet.
4. After knowing topology information of all the nodes in network, route calculation is
performed for getting all possible routes to destination in the network.
5. Route calculation:
• Residual Energy Approach
i. Remove all entries for route.
ii. Residual energy of each node is compared with threshold value then following
steps are taken into consideration for route selection,
If residual energy of node is greater than threshold value then;
a) Add new routing entries with symmetric neighbors (h=1) as destination nodes i.e.
1-hop neighbors
b) New route entries for destination nodes h+ 1 hop are recorded in routing table.
The new route entry is recorded by incrementing h by one each time till the
destination node is achieved.
• Energy Consumption Approach
i. Remove all entries for route.
ii. Energy consumed by each node is compared with threshold value then following
steps are taken into consideration for route selection,
If residual energy of node is greater than threshold value then;
a) Add new routing entries with symmetric neighbors (h=1) as destination nodes i.e.
1-hop neighbors
b) New route entries for destination nodes h+ 1 hop are recorded in routing table.
The new route entry is recorded by incrementing h by one each time till the
destination node is achieved.

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4.3. Working of EOLSR-RE and EOLSR-EC
Figure 2 shows working of modified protocol from network initialization to routing of data
packets from source to destination.
Figure 8.Working of EOLSR-RE and EOLSR-EC
5. SIMULATOR DETAILS AND QOS PARAMETERS
QualNet [11] is the first commercial simulator developed at the University of California, Los
Angeles (UCLA). QualNet has a graphical user interface (GUI) for creating the model and its
specification. So it is easier to specify small to medium networks by using the GUI compared to
specifying all connections in a special model file manually. QualNet is a network simulator
targeting at large wired and wireless networks. Qualnet is simulation software that provides
simulations of MANET under different network conditions. Its environment and libraries are
very sophisticated, which makes it very easy to simulate a real network with QualNet. It is used
to predict the behaviour and performance of networks. In simple words, QualNet is described by
using features such as speed, scalability, portability and extensibility. To analyze performance of
EOLSR-RE over OLSR in Mobile Ad-hoc environment, we used QualNet version 5.0.2.
5.1. Simulation Models
A simulation model consists of Energy Model, Battery Model, Traffic Model and Mobility
Model. The specifications for these models used in our experimentation are discussed as below;
5.1.1. Energy Model
The User-defined energy model [12] is a configurable model that allows the user to specify the
energy consumption parameters of the radio in different power modes. The total power required
for transmission, reception, idle (node is listening the medium) and sleep (node is not capable to
detect signals so communication is not possible) modes is given in Table.

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Table 1. Power requirement for different modes
Power requirement for different modes (Supply
voltage 3V)
Power Values
Transmission Power 0.84 Watts
Reception Power 0.612 Watts
Idle Power 0.534 Watts
Sleep Power 0.042 Watts
5.1.2. Battery Model: Linear Model
Nodes in the mobile ad-hoc network are battery operated. Hence, battery models are useful tools
for such types of system design approach; because they enable analysis of the discharge
behaviour of the battery under different design choices for example power management policies.
We used Linear Battery Model for the experimentation.
5.2.3. Traffic Model
Constant Bit Rate (CBR) sources represent voice sources and ftp sources are the ones used for file
transfer applications. We focus on Constant Bit Rate (CBR).The packet size is limited to 512
bytes. The source-destination pairs are chosen randomly over the network. The source-destination
numbers are fixed (called connection number).
5.2.4. Mobility Model
We used random way point mobility model where nodes in network moves randomly in any
direction with given speed.
5.2. Quality of Service (QoS) Parameters
5.2.1. Average End to End Delay
It is the average source-to-destination data packet delay including propagation and queuing delay
[13]. For a highly interactive application such as IP phone, end-to-end delays smaller than 150 ms
are not perceived by human listeners. Lesser end-to-end delay implies better performance.
5.2.2. Packet Delivery Fraction (PDF)
Ratio of number of packets successfully received by destination nodes to number of packets sent
by source nodes.PDF describes information about packet loss rate [14]. Higher value of PDR for
network indicates the better reliability of protocol.
5.2.3. Energy Consumed
Total energy consumed required to transmit all data packets to destination node. To achieve better
energy efficiency, energy consumed should be as low as possible [15]. The less energy
consumption by nodes extends the network lifetime i.e. nodes in the network can communicate
for longer period.
5.2.4. Control Overheads
The total number of routing packets transmitted for each delivered data packet [16]. Lesser
control overheads indicate that saving of energy in the network. Larger overheads utilise large
bandwidth which cause congestion in the network. Hence, control overheads should be less.
6. SIMULATION RESULTS AND PERFORMANCE ANALYSIS
6.1. Impact of Variation of Node Density and Node Speed
To analyze performance of EOLSR-RE and EOLSR-EC over OLSR, the numbers of nodes as
well as node speed are varied and compared with the help of QoS parameter discussed in section
5. Numbers of nodes are varied from 20 to 100 for fixed area to analyse performance of sparse

32
and dense network. Speed is varied to study the impact mobility of node on network. Number of
connections for simulations should be half as that of nodes present.
Table 2.Simulation Table
Parameters Variation of
Number of Nodes
Variation of Node
speed
Variation of Network
Area (in square meter)
Area 870x870 870x870 500,750,1000,1250,1500
Nodes 20,40,60,80,100 50 50
Node Speed 3m/s 1,3,5,8.10 m/s 3 m/s
Simulation Time 500 s 500 s 500 s
Traffic Type CBR CBR CBR
Traffic Sources 9,18,27,36,45 20 16,18,20,22,24
Packet Rate 2 packets/sec 2 packets/sec 2 packets/sec
Initial Power 30 mAHr 30 mAHr 30 mAHr
Routing Protocol EOLSR,OLSR EOLSR,OLSR EOLSR,OLSR
6.1.1. Average end to end delay
Figure 10: Impact of Variation of Number of Nodes and Node Speed on Average end to end
delay
Figure10 depicts end to end delay for EOLSR-RE, OLSR and EOLSR-EC protocols for number
of nodes from 20 to 100 and node speed 1 to 10 m/s. It is clear that EOLSR-RE has shortest delay
than EOLR-EC and OLSR. On an average EOLSR-EC shows better performance than OLSR
after 80 nodes and for all speed. For sparse network delay is almost same for all three protocols
while for dense network EOLSR-RE shows shortest delay.

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Table 3.Impact of variation of Network Area on Average end to end delay
As shown in Table 3, the average end to end delay increases with increase in network area. On an
average, there is 10% less delay in EOLSR-RE and 5% less delay in EOLSR-EC. It is seen that as
network area increases delay has higher value in all three protocols.
Note: In presented Tables, +ve sign shows higher value of EOLSR parameter as compared to
OLSR while –ve sign shows lesser value.
6.1.2. Packet Delivery Fraction (PDF)
Figure 11: Impact of Variation of Number of Nodes and Node Speed on Packet Delivery Fraction
The impact of variation of nodes and node speed on packet delivery is as shown in Figure 11.It is
seen that packet delivery is almost same over the entire node range and it shows decreasing trend.
For lower speed EOLSR-RE has better packet delivery than OLSR and EOLSR-EC while for
higher speed packet delivery is almost same for all three protocols. It is observed that PDF falls
with increasing node speed.
Network
Area
Average end to end delay
EOLSR-
RE
OLSR
EOLSR-
EC
% Change in
EOLSR-RE
% Change in
EOLSR-EC
500 20.4776 20.4522 20.4255 0.254424 0.130548
750 30.603 30.651 30.6912 -0.28821 -0.13115
1000 26.3986 30.551 32.0975 -21.5879 -5.06203
1250 29.9792 31.5423 32.7616 -9.2811 -3.8656
1500 28.0124 29.1243 30.3985 -8.51801 -4.37504

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Table 4.Impact of variation of Number of Connections on Packet Delivery Fraction (PDF)
As shown in Table 4, packet delivery decreases with increase in network area. It is seen that for
network area from 500 to 1000, packet delivery is above 90%.
6.1.3. Energy Consumption
Figure 12: Impact of Variation of Number of Nodes and Node Speed on Energy Consumption
Figure 12 shows effect of node variation and speed variation on energy consumption. In case of
EOLSR-RE, energy consumption has lesser value than OLSR and EOLSR-EC which is almost
20% less than OLSR and 10% less than EOLSR-EC. It is seen that for three protocols there is
increasing trend of energy consumption for both cases number of nodes and node speed variation.
Network
Area
Packet Delivery Fraction (PDF)
EOLSR-
RE
OLSR
EOLSR-
EC
% Change in
EOLSR-RE
% Change in
EOLSR-EC
500 0.9825 0.98 0.974 0.2551 -0.612245
750 0.9163 0.9041 0.9095 1.34941 0.59728
1000 0.8884 0.879 0.88 1.0694 0.11377
1250 0.782 0.763 0.7715 2.49017 1.11402
1500 0.7311 0.725 0.7295 0.84138 0.62069

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Table 5.Impact of variation of number of connections on Energy Consumption
The energy consumption reduces by 15% in EOLSR-RE and 7% in EOLSR-EC as shown in
Table 5. It is observed that energy consumption decreases with increase in network area.
6.1.4. Control Overheads
Figure 13: Impact of Variation of Number of Nodes and Node Speed on Control Overheads
The control overheads for EOLSR-RE are 50% less than OLSR and 25% less than EOLSR-EC as
shown in Figure 13. The control overheads are increases with increase in number of nodes while
remains constant for increase in node speed.
Table 6.Impact of variation of number of connections on Control Overheads
Network
Area
Energy Consumption
EOLSR-
RE
OLSR
EOLSR-
EC
% Change in
EOLSR-RE
% Change in
EOLSR-EC
500 8.75221 8.7973 8.773 -0.512544 -0.276221
750 11.8435 12.1369 12.003 -2.417421 -1.103247
1000 12.5696 14.7226 13.651 -14.62378 -7.278606
1250 11.484 13.6699 12.654 -15.99061 -7.431656
1500 10.7062 11.0749 10.991 -3.32915 -0.757569
Network
Area
Control Overheads
EOLSR-
RE
OLSR
EOLSR-
EC
% Change in
EOLSR-RE
% Change
in EOLSR-
EC
500 10471.18 11019.04 10922.11 -4.971939 -0.879659
750 7661.66 13119.86 9211.21 -41.60258 -29.79186
1000 7382.28 17389.76 8654.32 -57.54812 -50.23324
1250 9352.72 16247.58 14312.21 -42.43623 -11.91174
1500 8256.58 14394.06 12346.12 -42.63898 -14.22767

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There is almost 40% reduction in control overheads in EOLSR-RE and 15% reduction in
EOLSR-EC as shown in Table 6. Control overheads decreases with increase in network area
which indicates there is more impact of network area on control overheads.
7. CONCLUSION
Experimental results demonstrate that the proposed EOLSR-RE protocol results in a 20 percent
and EOLSR-EC protocol results in 10 percent of energy saving and this saving is obtained
starting from the transmission of the first packet. Subsequent packets transmitted using the
EOLSR-RE and EOLSR-EC protocol will result in further energy savings. From this discussion,
we can say that EOLSR-RE is best protocol in terms of energy efficiency.
Using the Qualnet simulator, we compared EOLSR-RE and EOLSR-EC with OLSR for number
of nodes variations. After analyzing results, it is seen that EOLSR-RE is delivering approximately
similar number of packets than OLSR, consuming less energy, requires less control overheads
and less end to end delay. Our simulations showed that OLSR-RE is able to improve network
lifetime and save energy. This indicates EOLSR-RE is an energy efficient routing protocol and
can be used where energy saving is an important criteria. EOLSR-RE is suitable choice in
military applications, disaster recovery areas and remote areas such as forests where energy
saving is important need.
8. FUTURE WORK
Future work can be extended for combination of both energy consumption and residual energy.
Later comparison of all three techniques can be done to check the best approaches as per
requirement.
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37
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Authors
1. Mayur Tokekar received the B.E. degree in 2008 from Dr.Babasaheb Ambedkar Mararhwada
University. He is currently a M.Tech student at College of Engineering, Pune. He is pursuing his M.Tech in
the field of Digital Systems. His areas of interests are wireless communication, embedded systems and
image processing.
2. Radhika D. Joshi received the BE degree in 1993 from Pune University and ME Degree from Pune
University in 2002. She is currently a PhD student at the University of Pune. She is pursuing research in the
field of Wireless Mobile Ad hoc networks energy management issues. At present she is serving as
Assistant Professor at Electronics and Telecommunication Engineering department of College of
Engineering Pune, which is an autonomous institute of Government of Maharashtra. Her areas of interests
are wireless communication, signal processing and electronic devices and circuits. She has received grants
for two research proposals from two funding agencies recently. She has published several papers in
journals and international conferences.

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