Design and implementation of variable range energy aware dynamic source routing protocol

INTERNATIONAL January- February (2013), © IAEME ISSN 0976-6367(Print), ISSN 0976 –
International Journal of ComputerJOURNAL OF COMPUTER ENGINEERING
6375(Online) Volume 4, Issue 1,
Engineering and Technology (IJCET),

& TECHNOLOGY (IJCET)
ISSN 0976 – 6367(Print)
ISSN 0976 – 6375(Online)
Volume 4, Issue 1, January- February (2013), pp. 105-123
IJCET
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DESIGN AND IMPLEMENTATION OF VARIABLE RANGE
ENERGY AWARE DYNAMIC SOURCE ROUTING PROTOCOL
FOR MOBILE AD HOC NETWORKS

Shiva Prakash
Department of Computer Science & Engineering,
Madan Mohan Malaviya Engineering College,
Gorakhpur, INDIA
shiva.plko@gmail.com
J. P. Saini
Madan Mohan Malaviya Engineering College,
Gorakhpur, INDIA
jps_uptu@rediffmail.com
S.C. Gupta Sandip Vijay
Department of ECE Department of ECE
Dehradun Institute of Technology, Dehradun Institute of Technology,
Dehradun, INDIA Dehradun, INDIA

ABSTRACT

Nodes in decentralized infrastructure-less wireless networks have limited battery
power. Thus energy is the one of the most challenging issue, majority of the research work in
energy efficient routing is based on the constant transmission power model, where nodes are
transmitting the data with its constant power which minimizes number of forwarding nodes.
Conversely, it results in interferences and decreases network lifetime. In this paper, we have
designed variable range energy aware dynamic source routing in which the route selection
based on energy, stability and load aware. We select two routes main and alternate; due to
this we are able to reduced requirement of number of route discoveries. In this approach
nodes are transmitting message with variant transmission power approach means that
transmission power dynamically tuned as per nodes distances. Network performance is tested
using NS-2 and their simulation results shows that a significant improvement in performance
of modified DSR was achieved.

Keywords: Ad Hoc Network, Routing, Power Aware Routing, Stability, Traffic Load,
Variable Range Transmission Power.

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International Journal of Computer Engineering and Technology (IJCET), ISSN 0976-6367(Print), ISSN 0976 –
6375(Online) Volume 4, Issue 1, January- February (2013), © IAEME

I. INTRODUCTION

Major research efforts have been focusing such as unreliable wireless links, limited
energy, security, and dynamic network topology. Energy efficient routing is one the
important issues in MANETs. Thus design an energy efficient routing approaches to save the
energy consumption of the network because all the nodes are battery powered. Failure of one
node may affect the entire network for the reason that nodes involved not only in data
communication but also in forwarding data on behalf of other. If a node runs out of energy
the probability of network partitioning will be increased. Thus routing in mobile ad hoc
network should be in such a way that it consider to use the remaining battery power in an
efficient way with stability and traffic load to increase the life time of the ad hoc network. To
bring about the goal in receipt of longer lifetime for a network, we must minimizing nodes
energy consumption not only during active communication but also when nodes are in
inactive state. There are two approaches to minimize the active communication energy [1] as
transmission power control and load balancing approaches and to minimize energy during
inactive approach as sleep/power-down mode.

The majority of energy efficient/energy aware routing protocols for ad hoc network
try to reduce energy consumption. These protocols try either to route data through the path
which minimize the end-to-end transmission energy for packets [2]. The aim of energy-aware
routing protocols is to reduce energy consumption in transmission of packets between source
and destination. In recent years most of the research work in this field is based on the
constant transmission power model, so, nodes transmitting the data with constant power
which improves network performance by reducing the number of forwarding nodes.
Conversely, it results in interference and decreases network lifetime. Only very few works in
which they used variant power model but route selection is not based on stability, energy and
load factors in unified way. In this paper, we have designed variable range energy aware
dynamic source routing in which the route selection is based on stability, energy and load
factors in unified way, so we are able to select the route which is more stable, energy
efficient. We minimize route reply by sending RREP to only two RREQs which have
maximum path selection factor values due to this we are able to reduced number of route
reply. In this approach, nodes are transmitting message with variant transmission power
control approach so the transmission power dynamically tuned as per nodes distances i.e.
hop-by-hop power control. Calculation of required power to transmit packet to next hop in
the path has done at each node with help of GPS. In this paper first of all We describes the
analytical models of stability, energy, variant power model and traffic load after that we
presents algorithms for the modified route discovery process and route maintenance process.
This protocol reduces the total energy expenditure in the network and thus maximizes the life
time of the network. Our simulation studies show that the proposed modified protocols are
more efficient than the existing one.

The rest of the paper is organized as in section 2 presents literature review we review
the conventional DSR protocol and other relented works, section 3 presents different models
used in our proposed approach. Section 4 presents design and implementation of VREA-
DSR in NS-2; simulation results and analysis is presented in section 5, finally we provide
conclusion in section 6.

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II. RELATED WORKS

Since routing is a most important and significant energy-consuming activity in ad hoc
networks, more research attention has been committed for designing energy-efficient routing
protocols. In this paper we describe the various research efforts done in the area of power-
aware routing protocols.
This routing protocol based on global information was proposed on [3], such as data
generation rate or power level information of all nodes (node costs), may not be convenient
because each node is provided with only the local information like distance between nodes
and other. The authors assumed that the power needed for transmission and reception is a
α
linear function of d where d is distance between the two adjacent nodes and α constraint that
depends on the physical environment. The optimal route selection, node evaluates and
compares the power expenditure of each path candidate. Power utilization of the direct
α
transmission, p(d), can be calculated if the distance is known, i.e., p(d)=a d + c, where a and
c are constants, d is the distance between two nodes and α is 2. The authors make used of
GPS to get location information to transmit packets with the minimum necessary transmit
energy. The key requirement of this technique is that relative positions of nodes are known to
all nodes in the MANET. However, this information may not be readily available.
Variable Range DSR [1][3] the use of variable range transmission for packet
transmission, it improved the drawback of general range transmission in terms of energy
used. Author has used DSR for our experimentation. Energy efficient design of the protocol
can be generated using the variable transmission range. The modifications in the MAC layer
are done, as it is major part of controlling the different parameters of network behavior.
Author has analyzed the impact of variable-range transmission power control on the energy
savings of wireless multi-hop networks. A power control technique affects the physical layer
performance. The choose of the high transmission range reduces the number of forwarding
nodes needed to reach the destination, but creates large interference. Due to this we can
reduces the transmission range demands more number of forwarding nodes but energy
utilization is less. The assessment of different parameters for the network is done for both the
protocols. Range is an important necessity for any RF application. This modified protocol
show the improvement in number of active nodes, network lifetime is due to variable range
transmitter power adjustment done at every node before transferring the data. This makes
effective utilization of different nodes in the network. In this modification not considers the
path selection on the basis of the energy aware and other factors.
The DSR protocol [4][5] belongs to the class of reactive protocols and allows nodes to
dynamically discover a route across multiple network hops to any destination. Dynamic
source routing means that each packet in its header carries the complete ordered list of nodes
through which the packet needed to pass. DSR uses no periodic routing messages, due to this
we are reducing network bandwidth and delay overhead, conserving battery power and
avoiding large routing updates throughout the ad-hoc network. Instead DSR relies on support
from the MAC layer (the MAC layer should inform the routing protocol about link failures).
The DSR protocol [6] is designed primarily for mobile ad hoc networks of up to about two
hundred nodes and is designed to work well even with very high rates of mobility, when
number of nodes is increasing its performance detonated very fast. It has two main phases as
route discovery and route maintenance, which work collectively to allow nodes to determine
and maintain routes to random destinations in the ad hoc network. Route reply would only be
generated when the message has reached the projected destination node. To return the route
reply, the target node must have a route to the source node. If the desired route is in the
destination node's route cache, the path would be used otherwise, the node will reverse the

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path based on the path record in the route reply message header (this requires that all links are
symmetric). In case of communication error, the route maintenance phase is initiated whereby
the route error packets are generated at a node. The erroneous hop will be removed from the
node's route cache; all routes containing the hop are condensed at that point. Again, the route
discovery phase is initiated to establish the most feasible route. The major difference between
this and the other on-demand routing protocols is that it is beacon-less and hence does not
need periodic hello packet (beacon) transmissions, which are used by a node to inform its
neighbors of its existence. The fundamental approach of this protocol, during the route
creation stage is to establish a route by flooding route request packets in the network. The
destination node, on in receipt of a route request packet, responds by convey a route reply
packet back to the source, which carries the route traversed by the route request packet
received.
Dynamic Source Routing (DSR) [4][6] protocol is a milestone in this development but it
has various shortcomings like
• The route cache used without their validity checks which degrade the performance if
invalid cache tried to use.
• This protocol performs well in static and low-mobility environments, as well as when
number of nodes not more than two hundred; the performance decreases quickly with
increasing mobility.
• DSR is not energy efficient as mobile nodes have limited power supply and energy
efficient protocols are essential for routing in MANETs so proper modification of
DSR is required.
• DSR does not consider the energy efficiency in route discovery. When multiple routes
then DSR select the route on basis of minimum hop count which could result poor
route selection.
• It used constant transmission power for transmission of packets, nodes transmits
information with constant power which increases interference of the signals.
In [7][8] geographic routing algorithms are a promising candidate for large-scale
wireless ad hoc networks. It takes advantage of the location information of the nodes are the
very valuable for wireless networks. In geographic routing protocols every node is aware of
its own position in the network; via mechanisms like GPS or distributed localization schemes.
This can save a lot of protocol overhead and consequently, energy of the nodes. The most
significant difference between MANETs and traditional networks is the energy constraint.
However, the majority of geographic routing algorithms take the shortest local path, depleting
the energy of nodes on that path easily. Thus, Energy efficient geographic routing techniques
play a significant role in saving the energy consumption of the network.
Link stability based routing [1][9] where nodes should keep an up-to-date information
about link status. In prediction-based link availability estimation algorithm is used to develop
a metric for path selection in terms of path reliability, which is improving the network
performance. The dynamic nature of MANETs leads difficulty in maintaining the precise link
state information. Main causes of path breakage, due to node’s mobility and or power
depletion of the mobile hosts. The mobility factor and energy factor to calculate the link
stability metric as Link Stability Degree (LSD) is defined as
LSD = Mobility factor / Energy factor
It means that the degree of the stability of the link depends on the value of LSD. Higher the
value of LSD, higher is the stability of the link and greater is the duration of its existence.
Weight Based DSR (WBDSR) [10] is enrichment to the existing DSR protocol.
Node’s weight is computed on the basis of stability and battery backup. Battery backup is the
main constraint to improve energy efficiency in DSR protocol. WBDSR improves the

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stability of nodes because on receiving RREQ all nodes calculates their node weight and
added to their battery life and stability in header of RREQ and before further broadcasting
and at every intermediate node this process is repeated. When RREQ reached to destination
node it waits for a small predefined time t for additional route requests. After that destination
node computes minimum of node weight among all nodes all received route requests then
send RREP to maximum route weight of the path. As insertion of own weight value by all
node to route request packet, the packet size increases fast which causes overhead to each
intermediate node and if the route has several intermediate nodes then overhead becomes
severe.
Minimum total power routing (MTPR): Various power aware routing proposals for
MANETs are investigated in [11]. MTPR is one of the routing proposals belong to this
category tries to minimize the total transmission power consumption of nodes participating in
an acquired route. The main goal of this routing protocol is to minimize the total
transmission power for route R. But in route selection process it does not consider the energy
level of the mobile node battery source during energy efficient route computation. This
approach may select the route that includes one or more mobile node with smallest amount
energy level
Minimum Battery Cost Routing (MBCR) protocol [12] used battery power always by
using a cost function which is inversely comparative to residual battery power. The route is
defined on the basis of sum of costs of nodes that are the major components. The route
selection is based on the minimum total cost. MCBR protocol can expand the network
lifetime due to selection of route whose nodes have high enduring battery power. The main
drawback of MCBR is that it may select a rather short path containing mostly nodes with
high enduring battery capacity but also a few nodes with lower remaining battery capacity.
The cost of this routing solution may be lower than that of a path with a large number of
nodes all having medium level of remaining battery capacity. Although, the previous routing
solution is in general less desirable from the network extended existence point of view since
such a path will become disconnected as soon as the extremely first node on that path dies.
Minimum Energy Routing (MER) [13] protocol includes the power levels that should
be used by all intermediate nodes. Processing of these levels done during initial phase when
all receiving intermediate node calculates the required power from the knowledge of transmit
power and received power. MER protocol has eight options, few in firmware and others are
implemented in software.
Min-Max Battery Cost Routing (MMBCR) protocol [11] considers the residual
battery power capacity of nodes as the metric in order to make longer the lifetime of nodes.
Let ci(t) be the battery capacity of host ni at time t. We can define fi(t) as a battery cost
function of host ni. The smaller amount capacity it has, the more reluctant it is to forward
packets; the proposed value is: fi(t) = 1/ci(t). It selects the route with the minimum path cost
among possible routes. Because this metric takes into account the remaining energy level of
individual nodes instead of the total energy, the energy of all nodes can be regularly used.
The limitation of this algorithm is that since there is no guarantee that paths with the
minimum hop-count or with the minimum total power are selected.
The minimization of energy consumption of mobile nodes try to adjust the
transmission power of wireless nodes [14][15]. Finding the energy efficient (min-power)
route [16] and to finding the least cost path in the weighted graph and power aware localized
routing [3] protocols of this category. The main concept, to balance the energy consumption
by avoiding low energy nodes when selecting a route. The minimum energy routing scheme
is not only to provide energy efficient routes [2][17] but also to formulate the given route
energy efficient by adjusting the transmission power just enough to reach to the next hop
node. The smallest common power (COMPOW) protocol [11] shows a straightforward

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solution to maintain bi-directionality between whichever pair of communicating nodes in a
MANET. Other articles tend to efficiently manage a sleep state for the nodes: various
solutions range from pure MAC-layer solutions (power management of 802.11) few more
solutions with combining MAC and routing techniques [8]. There are many other proposals
based an energy efficient routing protocol which are capable of routing data over the
network and of saving the battery power of mobile nodes [12][18]. And also some proposals
aim to add energy-aware functionalities to existing DSR protocols [19]20].
Energy aware protocols of ad hoc networks nodes are defined as data delivered in
one hop to the total energy expended in multi-hop. Overall minimizing energy consumption
is an significant challenge in multi-hop ad hoc networking. The related study [21][22] shows
that energy efficient/energy aware routing all these protocols have improvement over existing
protocols in energy point of view. Our motivation to consider as one of the important design
objectives to minimize network breakage means that extend the life of network.

A. Problem Identification
Lot of research has been conducted in current years to build up different approaches
to convey energy efficient routing in MANETs. Many improvements to existing DSR have
been discussed, and observed that these approaches make them energy efficient but they have
limitations also. Few limitations are as follows:
• In DSR protocol, the RREP send through all the available route large number of
unnecessary route replies leading to waste of energy. This protocol has not considered
energy efficiency in their path selection and routing of the packets.
• If there is any error due to depletion of node leads to link broken then nodes inform to
source, now source send remaining packets by route available in their route cache, but
this route may not be valid more, then route discovery initiated hence consume more
energy and increase the packet delay time.
• The protocol weight based DSR used battery power and stability of node to compute
node weight each node insert its node weight in route request packet which results packet
size keeps increasing very fast, if route have many intermediate nodes then overhead
becomes ruthless.
• Many more energy based modifications of DSR routing protocols have taken energy
based different metrics, but to the best of my knowledge there is know any work which
considered stability, energy efficiency and traffic load as well as variant transmission
power model.
All these routing protocols are assuming that all of the nodes in MANETs are battery
powered. Energy efficient routing approaches play a major role in saving the energy
consumption of the network. This motivated us for the search of new innovative approaches.
Thus, we have proposed a new energy aware dynamic source routing protocol, which used
variant transmission power model instead of fixed-transmit power as used in DSR and path
selection is based on stability, energy and traffic load. In next section, first we have discuss
stability model, energy consumption model, variant transmission power control and traffic
load model after this we describe working of our proposed protocol.

III. PROPOSED WORK

As we discussed in related work that maximum work done to minimize the flooding
in route discovery, or energy base route discovery, or in route maintenance or other metric
but to the best of my knowledge there is no any work which considered stability factor,
energy factor and traffic load factor all these three factor at a time as well as variant

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transmission power model for transmitting packet. Our proposed energy aware design of
DSR protocol has modified route discovery, route maintenance and packet transmission
strategies in energy efficient way. This protocol used variable transmission power model to
transmit packet.
The modifications in the MAC layer are also done, as it is main part of controlling the
various parameters of network activities. In this work, nodes are transmitting message with
variant transmission power control approach so the transmission power dynamically tuned as
per nodes distances i.e. hop-by-hop power control. Range is a significant requirement for any
RF application. Long range is achieved through larger receiver understanding. The best
receiver understanding is desirable as it lowers the power requirement allowing recognition
of weaker signals and can increase the transmission range. Calculation of required power to
transmit packet to next hop in the path has done at each node with help of GPS. This protocol
reduces the total energy expenditure in the network and thus maximizes the life time of the
network. Simulation studies show that the proposed modified protocols are more efficient
than the existing one

A. Network Model
We model an ad hoc network by a directed graph G = (N, E). N is the set of mobile
∈ ∈
devices and |N | = n. For i, j N, (i, j) E means that i is in the communication range of j
(but not necessarily vice versa). We assume that the network G is unknown, meaning that the
nodes do not have any knowledge about the nodes that can receive their messages, nor the
number of nodes from which they can receive messages by themselves. This assumption is
helpful since in a lot of applications the graph G is not fixed because the mobile agents can
move around (which will results in a changing communication structure). We analyze energy
cost function to the network layer and center of attention on routing algorithms. We discuss
how the error rate related with a link affects the overall probability of reliable delivery, and
consequently the energy allied with the reliable transmission of a single packet. For any
particular link (i, j) between a transmitting node i and a receiving node j, let Pi, j denote the
transmission power.

B. Stability Model
Link stability is always very augmenting problem of the mobile ad-hoc network. The
stability of a link [16] is given by its probability to persist for a certain time span, which is
not necessarily linked with its probability to reach a very high age. Stable path selection is
very fundamental criteria when we are talking about routing. The stability of the constituting
links, because the break of any link will lead to the break of the whole path. Thus, link
stability is anticipated to be obtained before the determination of path stability.
If relative position of node with its neighborhood doesn’t changes frequently then this is said
to be stable. Stability factor of node k is defined as follows.

Stability S fk =
((total numberof neighbor' s node) t −t1 − (number of absent nodes) t ) (1)
(total numberof neighbor' s node) t −t1
where Sfk is the stability factor of node k, t is the current time and (t – t1) is the time before t.

C. Energy Model
Energy aware communication in MANETs is needed to improve lifetime of the
network. Thus, we calculate the energy factor in view of residual energy of the node k at
particular instance [23]. The main steps of energy consumption during packet transmission
are as follows a) transmit, b) receive, c) idle, and d) sleep. The major sources of energy
wastage in MAC as collision, message overhearing, cost of control packet and idle listening.

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Nodes battery level affects the transmission range consequently we have to consider nodes
currently available energy to choose the optimal route. Energy factor of the node k is
calculated as the remaining energy of node k at instance is divided by total initial energy of
node k and remaining energy of node k considered as total initial energy of node k minus
energy consumed by node k. The energy consumption of node k is addition of energy
consumed when node k is in idle mode, energy consumed when node k is in active mode,
energy consumed when node k is in sleep mode and energy consumed when node k is in
transient mode. The values of power consumption measurements in a wireless ad hoc
network interface are selected IEEE 802.11 interfaces (2.4GHz). The energy dissipated in
transmitting (Etransmit) or receiving (Ereceived) in one packet can be calculated as follows:
Etransmit = Ptransmit × TD
Erecieved = Preceived × TD
where TD denote the transmission duration of the packet.
On the basis of energy and stability of node, we calculate factor of energy with stability, and
then we calculated minimum energy stability factor (ESf ) of the path.
ESfk= Efk + Sfk (2)
ESfsdi = Min {ESf1, ESf2, ESf3, ESf5,----, ESfNsdi}
where ESfsdi : Minimum value of the energy factor and stability factor of ith path
Nsdi : Set of node on ith path from source s to destination d ESf1, ESf2, ESf3,
ESf5,-----, ESfNsdi : nodes energy factor of ith path

D. Variant Transmission Power Model
Designing a variable-range transmission power control algorithm is more appropriate
to the needs of these promising wireless ad hoc networks to determine the appropriate packet
transmission energy at each node in a path through which communication packet can be
transmitted in more energy efficient. Changing from existing a common-range transmission
power design to a variable-range transmission power design is difficult in straight forward
transition, and in numerous cases requires a considerable re-design of the operation of the
system in order to increase enhanced power-conserving performance over existing systems.
We have used variable-range transmission power control to improve the overall performance
of wireless ad hoc networks. We considered that the coordinates are known by GPS at each
node and correspondingly known distances between nodes and then calculate desired power
to transmit packet. At every node in a path calculated transmission power for transition of
packets and stored in their cache if any change occurs correspondingly updated their cache.
We assumed that all packets are of a fixed size, Ei, j energy involved in a packet transmission
over link (i, j) is simply a fixed multiple of Pi, j. There are two factors: attenuation due to the
medium, and interference with ambient noise at the receiver which affected to any signal
transmitted. The attenuation is relative to Dα, where D is the distance between the receiver j
and the transmitter i. The bit error rate associated with a particular link is essentially a
function of the ratio of the received signal power to the ambient noise. In the constant-power
model, Pi, j is independent of the characteristics of the link (i, j) and is a constant. In this case,
a receiver situated further away from a transmitter will suffer greater signal attenuation
(proportional to Dα) and will, accordingly, be subject to a larger bit-error rate. In the variable-
power model, a transmitter node adjusts Pi, j to ensure that the strength of the (attenuated)
signal received by the receiver is independent of D and is above a certain threshold level Th.
The minimum transmission power associated with a link of distance D in the variable-power
model is Pm = Th × γ ×Dα, where γ is a constant and α is the coefficient of channel attenuation
(2≤ α ≤ 6). Since Th is usually a technology-specific constant and considered α =4, we can
see that the minimum transmission energy over such a link (i, j) varies as Em(D) Dα . ∝
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E. Traffic Load Model
The traffic load balance [23][24] also play major role in enhancing the network life.
As node in the high traffic load path will die off faster in comparison with nodes in the path
that have lower traffic load. So traffic load aware routing provides not only a smaller end -to-
end delay, but also improve energy efficiency by efficient energy distribution of routing. The
network interface queue, a packet being transmitted could be queued in a variety of ways.
For example, outgoing packets from the network protocol stack might be queued at the link
layer, before transmission by the network interface. The network interface might also
provide a retransmission mechanism for packets, such as occurs in IEEE 802.11; the DSR
protocol, as part of Route Maintenance, requires limited buffering of packets already
transmitted for which the reach ability of the next-hop destination has not yet been
determined. The Network Interface Queue of a node implementing DSR is an output queue of
packets from the network protocol stack waiting to be transmitted by the network interface;
this queue is used to hold packets while the network interface is in the process of transmitting
another packet. The default queue size is 50 packets.
Traffic load factor is defined as follows:

Lfk = Qpk/ Qtk (3)
Qpk = Qtk - Qrk (4)
where
Qrk : Remaining network interface queue size of node k at instance
Qtk : Initially full interface queue size of node k
Qpk : At instance number of data packets in interface queue of node k
Lfk : Traffic load factor of node k
Now, traffic load factor of the ith route is calculated as follows:
∑ L fk
k∈N sdi
L fsdi = (5)
N sdi + 1
where
Nsdi : Set of node on ith path from source s to destination d
Nsdi + 1 : Number of nodes in ith path
Percentage of network interface queue that is occupied capacity of the node at the
instance as in section 3.4. The default maximum size of network interface queue is 50. Lfsdi
indicated the traffic load of ith path from source s to destination d that is occupied capacity of
network interface queue. The higher value of the Lfsdi indicates that route has maximum
traffic means congested route, such paths should avoided to choose because it leads to higher
packet loss and longer delay. We will choose the path which has lower Lfsdi value. The
integrated model is the combination of all three the energy factor, traffic load factor and
Stability factor. So, these factors use to calculate path selection factor is as follows:
ES fsdi
Pfsdi = (6)
L fsdi
The route will be selected with highest Pfsdi value for the data transmission.

F. Energy Aware Route Discovery Process
Route discovery process is desired when a source node S wishing to send a packet to
a destination node D, then source node see their route cache if route found, send validation
message and stat timer, if ACK received in before timer expire then node can send the packet
with this path, otherwise source node start route discovery process, required to discover the
energy efficient path. Using VREA-DSR obtains an energy, load and stability aware path

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from source route to destination. The process of energy aware route discovery is entirely on
demand. Energy aware route discovery procedure used a route request (RREQ) and route
reply (RREP) messages, to find a route from source to destination. When several source
nodes originates a new packet addressed to some destination node, the source node places in
the header of the packet a source route giving the sequence of hops along with the stable,
energy efficient and load balanced route at which the packet is transmitted for each hop.
Using GPS model to know the coordinates of each other’s nodes thus node calculate distance
between nodes and corresponding desired transmit power as in section 3.4 so that receiver
can receive it.

Algorithm 1: Route Discovery Process in VREA-DSR
Step 1: Source node have packet to send, check route cache
If (route to D is found)
{
prepare route validation message send to path mentioned in route cache and start timer
If (ACK arrived before timer expires)
{
Send data packet by this path
}
}
Else
{
Prepare RREQ message, initialize SEf = (Sf = Maximum value (i.e. 1) + Ef = Maximum value
(i.e. 1)) = 2; Lf = 0 and transmission power and append these value to RREQ header
then broadcast to their neighbor.
}
Step 2: If (power of node < α && Neighbor ≠ Destination)
{
Discard RREQ packet
}
Else if (power of node ≤ || ≥ α && Neighbor = Destination)
{
If ( it is first root request )
{
calculate Pf1 and store into RREQ table and node waits for ∆ t time for
more RREQ;
}
Else if ( it is next RREQ && time < ∆ t time)
{
calculate Pf2 Pf3, Pf4,...,Pfn and also stored in RREQ table;
}
Else if (more than two RREQ && time = ∆ t time)
{
See RREQ table and compare RREQ’s Pf’s value; destination send
RREP packet with these two RREQ paths which have highest and next
highest Pf values (means main path and alternate path)
}
Else if (less than or equal to two RREQ && time ≤ ∆ t time)
{

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Destination send RREP packet with these two RREQ paths (means
main path and alternate path)
}
else
{
No update;
}
}
Step3: Else (power of node ≥ α && Neighbor ≠ Destination)
{
Neighbor’s node extract values RREQ header and calculate ESf = (Sf + Ef ) and
Lf calculate average value of Lf with nodes values of Lf, calculate transmission power;
If (node’s ESf < header’s ESf )
{
Replace hedader’s ESf = node’s ESf ; add values of ESf, Lf , and
transmission power in header’s field of, ESf , Lf; and power and broadcast
RREQ to their neighbor.
}
Else
{
No change in header’s value of ESf and replace header’s Lf with
calculated average value of Lf and broadcast RREQ to their neighbor.
}
}
Where Pf1 : Path factor of first RREQ message at particular instance
Pf2 : Path factor of second RREQ message at particular instance
Pfn : Path factor of nth RREQ message at particular instance
Algorithm 2: Route Maintenance Process in EA-DSR
Step 1: Source node sends data to destination node with the main path;
if (any node in route have ERR message)
{
Node send back RERR message to source node;
}
Step2: When source node received RERR message, check the alternate route in route cache;
if (alternate route found in route cache)
{
Send route validation message by alternate path mentioned in the route cache and start
timer;
if ( ACK received before timer expires)
{
Source send remaining data packet by this alternate path;
}
else
{
Source initiate new route discovery;
}
}
Modification of existing DSR header, we adds three more field in reserved field of basic
DSR header. We describe the packet structures for VREA-DSR and discuss the changes in
each packet option below.

115


IV. DESIGN AND IMPLEMENTATION OF VREA-DSR

In this section first we design packet structure as route request packet, route reply
packet, acknowledgement packet etc. and then provide ns-2 implementation details.

A. Design of Packet Structure for VREA-DSR Route Request (RREQ) Packet:
The receiving node of RREQ must compute the stability factor Sfk with energy factor
Efk, and traffic load factor Lfk of node k for this hop node according to stated three equations
(1), (2) and (5). Table I shows the RREQ packet format in VREA-DSR, by which efficient
route will be selected; the path selection factor.
Table I: Route Request Packet Format in VREA-DSR
IP DSR DSR Request ESf Lf DSR
Header Fixed Route Address. Source
Header Request [Src,1,......., Power to
Header N,dest] Pwr1…
to PwrN

Route Reply Packet: The reply paths based on energy, stability and traffic load in unified way
included path and alternate path in the new route reply packet format. As discussed in section
3.5 and 3.6, the RREPs are forwarded to the next hop defined on the source route addresses
[Src, 1…N, dest]. The source route for RREP is the reverse of source route of the RREQ.
Hence, the destination node reverses the source route of RREQ with maximum value of path
factor and also route reply to next maximum valued of path factor as alternate path to source
route of RREP. The table II shows the format of RREP packet that includes the energy aware
information for implementation of VREA-DSR.

Table II: Route Reply Packet format in VREA-DSR Data Packet Format:
IP DSR DSR DSR DSR DSR
Header Fixed Route source Reply Source
Header Reply Route Addresses Power
Header Header [Src,1..N, Dest] Pwr1… to…
PwrN

The power Pt value required that the packet is actually transmitted on the link. The power
Pt value considered to on the basis of distance of the link, a node chooses to change the
transmit power dynamically for hop i. Table III shows the data packet format for VREA-DSR
includes the DSR fields besides the special fields of VREA-DSR.

Table III: Data Packet Format in VREA-DSR
IP DSR DSR DSR DSR DSR Data
Header Fixed Route Source Reply Source
Header Header Route Addr. Power
Addr. [Src,1.. Pwr1…to
[Src,1 N, Dest] PwrN
…N,
Dest]

ACK Packet Format: The Acknowledgement option in a DSR Options header is encoded as
in order to allow nodes that have lost flow state to determine the previous hop, the address of
the preceding hop can optionally be stored in the Acknowledgement Request as given in table
IV. This extension used when a Source Route option is present, MAY be used when flow
state routing is used without a Source Route option, and SHOULD be used before Route
Maintenance determines that the next-hop destination is unreachable.

116


Table IV: ACK Packet Format in VREA-DSR
IP DSR DSR
Header Fixed Header Route Header

Route Error packet: These packets are generated at a node when the link-layer reports a
broken link at some stage in a data-packet transmission. When a node is unable to validate
reach ability of a next-hop node. It should send a Route Error to the source node of the
packet. When a node receives a packet containing a Route Error option, then that node must
remove from its route cache all the intermediate node repeat the same process, when RERR
message reach to source node check their route cache, is route to destination found, source
send route validation message to destination, and if received ACK of route validation
message received in time. Source sends remaining packets to destination with this path.
Otherwise, source initiates a new route discovery process to find new route to communicate
remaining packets. The route error packet format as given in table V.
Table V: Route Error Packet format in VREA-DSR
IP DSR DSR Unreachable DSR DSR
Header Fixed Route Node Source Source
Header Error Address Route Route
Header Header Addresses
[Src,1…N, dest]

B. Implementation of VREA-DSR in NS-2
This section presents the precise implementation of VREA-DSR intended for the proposed
solutions. Our proposed solutions are anticipated to make longer the lifetime of the network and
nodes. In this section we discussed the main function which required for implementing our proposed
protocol. The DSR, MAC, COMMON and QUEUE folders of NS-2.34 have been modified to
implement VREA-DSR. Most of the works have been done on modification of existing DSR program
files. The required changes made to existing DSR are to implement VREA-DSR in NS-2. Details of
the implementations of existing DSR protocol in NS-2 can be found in the documentation [17][25]. In
this section we present the changes made on existing DSR protocol for implementation of VREA-
DSR. Many C++ program files of existing DSR are modified in order to implement the desired
features of VREA-DSR in the NS-2 simulator. In addition to the DSR program files folder, further
supportive files folders are also modified like MAC, COMMON and QEUEU. Here are the modified
programs files of DSR protocol are as follows:
We have implemented required modification in dsragent.cc and dsragent.h and define other DSR
routing protocol in NS-2. The dsragent.cc is prepared in to functions. The functions are designed
based on their objective on routing activity. These implementations starts by incorporating the
computation of the ESf, Lf, and Pf (equations 2, 5 and 6) in handleCost(SRPacket &p) function in
dsragent.cc. HandlePacketReceipt and handleRouteRequest functions are modified to implement
energy aware route reque and route reply (in section 3.6) respectively. Existing ignoreRouteRequestp
function of DSR discards the copy of RREQ. In VREA-DSR, the function is modified to receive
multiple copies of RREQs. HandleRouteRequest function to decide to route reply on the basis of path
selection factor Pf route reply to RREQs in which Pf values maximum and next maximum, but reply
to maximum value of Pf RREQ with both main and alternate routes. replyFromRouteCache is
replaced by VREAreplyFromCache in this process we added to test its validity before we can use path
lies in their route cache. This function uncast the route request to the destination rather than reply the
route from cache to initiator of the request. VREADSR route reply send to only first two route request
not to all route request to minimize huge route reply to destination. Delay forwarding is handled by
the timer driven function. File dsragent.c is included this function with function name of rreq_purge.
The route is maintained during data communication, the destination node of the data must reply to the
source node. The DSR source route format is modified to handle power, stability aware and load
balanced information of VREA-DSR (section 3.4). In addition to the above source files, other source
files are also modified.

117


B.1 Changes made to other common folders to implement VREA-DSR
This COMMON folder includes a number of source files. packet-stamp.h is one of the most
important source file in COMMON folder. It defines the information which is embossed with the
packet. The sender node must trample vital information for VREA-DSR on the packet. This
information includes its node’s stability, residual batteryenergy, and traffic load i.e. is queue length.
The receiver node has to extract this information from the packet for further processes. The packet.h
file defined the packet structure. The packet structure contains headers and data energy, and traffic
load i.e. is queue length. The receiver node has to extract this information from the packet for further
processes. The packet.h file defined the packet structure. The packet structure contains headers and
data. The struct hdr_cmn is one of the general headers on the packet structure and this header is
accessed by every layers. structure. The packet structure contains headers and data. The struct
hdr_cmn is one of the general headers on the packet structure and this header is accessed by every
layers. Therefore, this is used to swap over information between the layers. In VREA-DSR protocol,
the remaining battery energy of receiver node is used for link cost computation on the network layer.
The physical layer should send the remaining energy of the node to the network layer using hdr_cmn.
These are many more mains modifications made to implement VREA-DSR in NS-2 simulator.
V. SIMULATION RESULTS AND ANALYSIS

An energy model is presented, based on 802.11, which considers different radio states; the
performance of network protocols [17][25] is agreed using network simulators ns-2. This approach is
computing more correct the energy consumption for Ad-Hoc network protocols. The advantages of
this particular energy models (802.11 DCF (Distributed Coordination Function) and SMAC) are the
consideration of all the possible radio states and that the simulator can calculate the energy
automatically irrespective of the stack the protocol at particular layer designer is working. In this
paper we use Network Simulator 2 version 2.34 [17][26] to perform comparison between VREA-
DSR and DSR protocols. NS2 is one of most popular network simulator tools worldwide. The NS2
was installed under Fedora 10.0 as a simulation platform. The simulation scene was for 1000 × 800
m2 rectangular region with movement speed 1 m/s to 5 m/s. The simulation parameters are defined as
give in table VI transmission range is assumed to be 250m, the number of CBR source nodes varies 3-
16 according to size of networks and nodes are selected randomly as CBR sources and the packet size
is fixed at 512 bytes. In order to have performance result, we used 10 to 100 nodes on the simulation.
We run several simulations and distinguish the results to two protocols, DSR and SELA-DSR, to
verify the superiority of the VREA-DSR protocol.
Table V1: Simulation Environment Parameters
MAC layer type IEEE80.11
Reception queue length 50
Radio propagation model TwoRayGround
Transmission power (txPower) 1.4W
Reception power (rxPower) 1.0W
Idle power 0.53W
Sleep power 0.13W
Initial energy 1000Jules
Transmission range 250 mtr.
Packet size 512 bytes
Channel Capacity 2Mbps
Frequency 2.4 Ghz
Transmitted signal power 0.2818 W
Packet generation rate 2 packets/second,
4p/s
Area - Environment Size 1000m x 800m
Number of nodes 10 - 100
Simulation time 600 seconds

118


Experimental result as shown in Figure 1. that energy consumption of each protocol on variation of
the number of nodes in the networks. The nodes variation in the networks is 10 to 100, and number of
CBR sources varies from 3 to 20 according to size networks. As considered each node initial energy is
set to 1000J. The average energy consumption increases in each protocol when number of nodes
increases although VREA-DSR consumes less energy than SELA-DSR and DSR due variable range
transmission control.

Figure 1: Energy Consumption verses number of nodes in the network

Figure 2: Packet delivery ratio verses number of CBR connections

The packet delivery ratio (PDR) is the number of packets received by the destination to the number
of packets transmitted by the source is shown in Figure 2. PDR reduces when increases the CBR
connections. It is considering 100 nodes scenario and observed that the VREA-DSR maintains a better
packet delivery ratio than the existing DSR and stability energy and traffic load aware DSR (SELA-
DSR).

Figure 3: Energy consumption per packet versus maximum speed of the node

119


In Figure 3 the simulation results are shows that VREA-DSR protocol performs the best in
terms of energy consumption per packet. As expected DSR performs the worst in terms of
energy consumption. As its path could not select on the basis of mobility or minimum energy
consumption. This is confirmed by the simulation results that as speed of node increases then
energy consumption per packet also increases in all protocols but in VREA-DSR perform
better than other two protocols.
In Figure 4, node alive count shows improvement for variable range energy aware dynamic
source routing (VREA-DSR) over SELA-DSR and DSR for duration of simulation. As the
transmitted power is dynamically adjusted according to distance in our VREA-DSR protocol,
it will successfully use available node energy increasing the Number of nodes alive.

Figure 4: Number of node alive verses simulation time in seconds

Figure 5: Network lifetime versus number of CBR connections

The metric network lifetime used to analyze the network partitions, 100 nodes are considered
for this scenario. Figure 5 shows the network lifetime decreases when we increase the
number of CBR connection. The network lifetime of basic DSR protocol is very less as
compared to two other energy aware protocols. The Network lifetime of VREA-DSR is better
than SELA-DSR and DSR due to the following main reasons. First, VREA-DSR implements
the variable range transmission power control which saves energy consumption. Second,
VREA-DSR selects the routes in which nodes have more energy and stability than other
paths. The minimum transmit power route reduces the over all energy consumption of the
network and minimize interference also.

120


VI. CONCLUSION

It is significant to design energy efficient routing protocols for mobile ad hoc networks. On
the other hand, without a cautious design, an energy efficient routing protocol might have
much worse performance than an ordinary routing protocol. It is observed that the use of
variable range transmission power control overcomes the drawback of common range
transmission power control in terms of energy consumption and improves network lifetime.
The node alive count shows improvement for variable range energy aware dynamic source
routing (VREA-DSR) over SELA-DSR and DSR due to transmitted power is dynamically
adjusted according to distance in our VREA-DSR protocol; it will successfully use available
node energy increasing the number of alive nodes. Also, our VREA-DSR protocols show
improvement over SELA-DSR and basic DSR as in packet delivery ratio, and energy
consumption.

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