Scholarly article on topic 'Energy Optimization in Manets Using On-demand Routing Protocol'

Energy Optimization in Manets Using On-demand Routing Protocol Academic research paper on "Computer and information sciences"

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Procedia Computer Science
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{"Mobile ad hoc networks" / Routing / "Hello messge" / DYMO / "Energy management" / "On demand routing."}

Abstract of research paper on Computer and information sciences, author of scientific article — K. Sumathi, A. Priyadharshini

Abstract Mobile Ad hoc networks (MANET) allow a set of wireless hosts to exchange information without any special infrastructure. The projct entitled “Energy Optimization in Manets using On-Demand Routing Protocol” motivates the need for energy management in ad hoc wireless networks. Limited battery power is one of the most important issues in mobile ad hoc network as the mobile nodes operate in limited battery power. Also there occurs a problem of broken links due to the lack of energy which cause disorder in network system. Such problem occurs due to the unawareness of energy of mobile neighbor nodes. This paper presents the implementation of Adaptive HELLO messaging scheme to determine the local link connectivity information for monitoring the link status between nodes along with the incorporation of Dynamic On Demand Routing Protocol to reduce the energy consumption of mobile nodes to certain extent.

Academic research paper on topic "Energy Optimization in Manets Using On-demand Routing Protocol"



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Procedía Computer Science 47 (2015) 460 - 470


K.Sumathia1, A.Priyadharshinib

aPG Scholar, Department of Computer Science and Engineering, Coimbatore Institute of Technology,

Coimbatore and 641014, India bAssistant professor, Department of Computer Science and Engineering, Coimbatore Institute of Technology,

Coimbatore and 641014, India


Mobile Ad hoc networks (MANET) allow a set of wireless hosts to exchange information without any special infrastructure. The projct entitled "Energy Optimization in Manets using On-Demand Routing Protocol" motivates the need for energy management in ad hoc wireless networks. Limited battery power is one of the most important issues in mobile ad hoc network as the mobile nodes operate in limited battery power. Also there occurs a problem of broken links due to the lack of energy which cause disorder in network system. Such problem occurs due to the unawareness of energy of mobile neighbor nodes. This paper presents the implementation of Adaptive HELLO messaging scheme to determine the local link connectivity information for monitoring the link status between nodes along with the incorporation of Dynamic On Demand Routing Protocol to reduce the energy consumption of mobile nodes to certain extent.

© 2015 TheAuthors.PublishedbyElsevier B.V.This is an open access article under the CC BY-NC-ND license (http://creativecommons.Org/licenses/by-nc-nd/4.0/).

Peer-reviewunder responsibility of organizing committee of the Graph Algorithms, High Performance Implementations and Applications (ICGHIA2014)

Keywords: Mobile ad hoc networks; Routing; Hello messge; DYMO; Energy management; On demand routing.


1.1 Introduction to Mobile Ad hoc Network (Manet)

MANET is one of the most emerging fields in research and development of wireless network. As the popularity of mobile device and wireless networks increased significantly over the past years, it has now become one of the most vibrant and active field of communication in wireless technology.

1877-0509 © 2015 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.Org/licenses/by-nc-nd/4.0/).

Peer-review under responsibility of organizing committee of the Graph Algorithms, High Performance Implementations and Applications (ICGHIA2014) doi: 10.1016/j.procs.2015.03.230

Figure 1.1 Mobile ad hoc Network (MANET)

MANET is a self configuring and infrastructure- less network. Each device or node is free to move independently, and will therefore change its links with other devices frequently in any direction. The primary challenge in creating a MANET environment is to continuously maintain the information required to route the traffic properly. Such networks can operate by themselves or by connecting itself to the larger Internet. They may contain one or more transceivers. This results in a highly dynamic and autonomous topology.

MANET has routable networking environment to process the exchange of information or packet from one node to other node. Different protocols are simulated for measuring the packet drop rate, the overhead introduced by the routing protocol, end-to-end delay of packet, network throughput, etc.

This paper proposes an implementation of Adaptive Hello messaging scheme and Dynamic On-Demand routing protocol to establish a link and efficiently utilize the energy to enhance the life of network.

The rest of this paper explains the advantages of MANET, various routing protocols is MANET, overview of previous proposals, including proposed work, finally the last section contains the performance evaluation of proposed system.


Ad hoc networks are suited for the situations where an infrastructure is unavailable, and it is simple and fast, not cost effective to deploy too. The following are some of the important application related to MANET,

> Business application,

> Military application,

> Emergency operations,

> Home, office, and educational applications,


> Wireless sensor networks, mesh networks,etc.


MANET Routing Protocols are typically subdivided into two main categories: Proactive Routing Protocols and Reactive Routing Protocols.


Proactive routing protocol is the one in which each node maintains its route to all other network nodes. The route creation and maintenance are performed by both periodic and event-driven messages. The various proactive protocols are Destination Sequenced Distance Vector (DSDV) [6], Optimized Link State Routing (OLSR) [10].


In Reactive routing protocol, the route between two node is discovered only when it is demanded which is considered as the important advantage since message overhead is reduced i.e., total number of control packet transmission is reduced. There are different types of reactive routing protocols such as Ad hoc On-Demand Distance Vector (AODV) [9], Dynamic Source Routing (DSR) [10], Dynamic MANET On-Demand (DYMO) [18].


An example of a hybrid routing protocol that combines both proactive and reactive approach, which brings the advantage of both the approaches together is Zone-Based Hierarchical Link-State Routing Protocol (ZRP). ZRP defines each node a zone around itself containing all neighbor nodes with certain 'k' hop (k=1,2 or 3). If the destination node's position is within the zone of source then it uses proactive routing else it uses reactive routing protocol.


Working of the Routing Protocol consists of 2 phases: Route discovery, Route maintanence.


When a node desires to send packets to a destination node, it first establishes a path to it for communication. The node begins the route discovery by broadcasting a route request (RREQ) message containing the IP address of the destination. When an intermediate node receives the RREQ, it records the reverse route toward the source and checks whether it has a route to the destination. If a route to the destination is not known, the intermediate node rebroadcasts the RREQ or if it has recent information about a route to the destination, route reply (RREP) message is generated. This RREP is unicast back to the source using the reverse route that is been recorded. When a RREP reaches the source, it begins to send data packets to the destination along the discovered path. If more than one RREP is received by the source, the route with the lowest hop count to reach the destination is selected.


This is the phase where the maintanence of link is preserved when broadcasting the packets.When a link breaks along an active path, the node upstream of the break detects the break and creates a route error (RERR) message. This message lists all destinations that are now unreachable, due to the link breakage and this information is sent to the source. Each intermediate hop deletes any broken routes and forwards the RERR packet towards the source. When the source receives this, it determines whether the packet still needs to be forwarded. If so, it begins the route discovery process for forwarding.


(a) Propogation of Route Request (RREQ) Packet

Fig.1 Propogation of RREQ, RREP


Battery energy is said to be a rare resource, and it often affects the communication activities between nodes in network. Communication takes place through direct links or through multi hop links. Due to the limited battery energy of mobile nodes, the lifetime of node becomes the key challenge. Controlling the transmission power significantly reduces the energy consumption for sending data packets and also increase lifetime of network. Nodes adjust the transmission power so as to achieve the minimum energy consumption according to the local information.

The idea of distributed power control can be used to improve energy efficiency of routing algorithm in MANET. There are some control messages such as RREP in On-Demand Routing Protocol which provide a strong indication that messages should trigger a node to switch to active node from sleep. Since the communication with a neighbor is only possible if the neighbor is in active mode, it is necessary for nodes to track energy modes of neighbors i.e., active, sleep or idle. The neighbor's power mode can be discovered in two ways: the first way is through explicit local HELLO message exchanges with piggybacked information about the energy management mode of a node, and the second way is via passive inference.

Energy efficiency is measured by the duration of the time over which a network can maintain a certain performance level, which is usually called as the nework lifetime.Using the power consumption is not only a single criterion for conserving energy efficiency. Hence, routing to maximize the lifetime of the network is different from minimum energy routing. Minimum energy routing sometimes attract more flows since the nodes in these route exhaust their enegy very soon. Hence, the whole network cannot perform many task due to the failure of these nodes. Routing with maximum lifetime balances all the routes and nodes globally so that it can maintain certain performance level for a longer time.

Hence saving energy at the time of broadcasting in order to recover from the node failure and during re-routing around failed node is essential.


Energy is said to be a limiting factor in case of ad hoc networks [3] [4] [11]. Routing in ad hoc network has some unique characteristics:

> Energy of node is crucial and it depends upon battery which has limited power supply.

> Nodes can move in an uncontrolled manner, so frequent route failures are possible.

> Wireless channels have lower and more variable bandwidth compared to wired network.

Energy efficient routing protocols are the only solution to above situation. Most of the work of making protocols energy efficient has been done by reactive routing rather than proactive routing protocols. Energy efficiency can also be achieved by sensible flooding at the route discovery process in reactive protocols. And it can also be achieved by using efficient metric for route selection such as cost function, node energy, battery level etc.

Here the efficiency not only refers to the successful delivery of packets with less consumption of power, but also refers to the increase in duration of maintaining the link between the nodes to ensure increase in performance. This can be achieved by using AODV & DYMO routing protocol.

Consider an example, of a multi-hop communication channels from A to B through an intermediate node C between them, see Fig. 1.3

Fig 2: A Simple Scenario for Energy Consumption in Multi-hop Networks.

There are two possible ways to communicate between A and B. One is to directly transmit data from A to B; or relay with Node B. However, these two different methods lead to two different level of energy consumption, in which one must be better. Transmitting a packet from A to B consumes less energy rather than sending the same packet toB through C.


2.1 A New Method for Restoration Broken Links in Wireless ad hoc Networks by Estimation Energy Consumption.

A novel method on energy estimation to restore broken links and reconstruction of the paths is proposed to investigate the effect of broken links on topology control and routing process in ad hoc network. It is indicated that these effects were harmful in the mentioned couple of network portions. This work [12] is used as Hardware Method for estimating energy in ad hoc node, and this method has high speed too. Hence, it helps to find out or investigate the effect of link breakage in ad hoc network. One may find that the use of routing protocol algorithm to estimate the energy and also to reconstruct the path will conflict. For this purpose a strategy was made in order to prevent link break and disordering which provide some suggestions to route the network through prediction and time estimation of link break.

2.2 Improving the Network Lifetime of MANETs through Cooperative MAC Protocol Design.

To relay the overhearing information to achieve greater efficiency a cooperative communication is proposed to utilize nearby terminals to transmit in wireless networks. In order to deal with the complicated medium access interactions induced by relaying and leverage the benefits of such cooperation an efficient Cooperative Medium Access Control (CMAC) protocol is needed. This paper [13] proposes a novel cross-layer Distributed Energy-adaptive Location-based CMAC protocol, namely DEL-CMAC. The design objective of DEL-CMAC is to improve the performance of the MANET in terms of network lifetime and energy. A practical energy consumption model is described that the nodes consume energy on both transceiver circuit and transmit amplifier. A distributed utility based best relay selection strategy is also incorporated, which selects the best path to route based on location information and residual energy. Also, to enhance the spatial reuse for the mobile nodes, an innovative network allocation vector setting is provided to deal with the varying transmitting power of the source and relay terminals. The result of proposed DEL-CMAC prolongs the network lifetime even for high circuitry energy consumption.

2.3 Power Management for Wireless Data Transmission using Complex Event Processing.

Energy consumption of wireless data transmission is a significant part in wireless mobile devices. It is context-dependent, i.e. it depends on internal and external contexts, such as application workload and wireless signal strength.This paper [14] proposed an event-driven framework for efficient power management on mobile devices when communicating. This framework adapts the behavior of a device component or an application to that change in contexts, according to event-condition-action (ECA) rules specified by the developer to describe the power management mechanism. It also supports complex event processing by correlating various events, and helps to discover complex events that are relevant to power consumption. This framework is evaluated with two applications in which the data transmission is adapted

to traffic patterns and wireless link quality. These applications can roughly save 12 percent more energy compared to normal operation. But this paper doesnot mention about the collaborative power management between the mobile nodes.

2.4 An Adaptive Hello Messaging Scheme for Neighbor Discovery in On-Demand Manet Routing Protocols.

In mobile ad hoc networks, local link connectivity information is extremely important for route establishment and maintenance. Periodic Hello messaging scheme is a widely-used to obtain local link connectivity information. However, unnecessary hello messaging can drain their battery power when mobile devices are not in use. This paper [17] proposes a messaging scheme to suppress unnecessary Hello messages without reduced detectability of broken links. Simulation result shows that the proposed scheme reduces energy consumption and network overhead without any explicit difference in throughput.

This scheme dynamically adjusts Hello intervals, and does not increase the risk of sending the packet through a broken link. To estimate unavailability of link between nodes, average time gap between two consecutive events is found. By monitoring the event intervals, state of a node can be estimated. If a node is not involved in any communication for a given period, then it does not need to maintain the status of the link, and broadcasting of hello packets during this period are unnecessary. If a constant Hello interval is used, the risk of attempting to transmit a packet through a broken link decreases as the event interval increases. Instead of using a constant Hello interval, proposed scheme uses a constant risk level. As the event interval increases, the Hello interval can also be increased without increasing risk.

This proposed scheme result in reduced battery power through practical suppression of unnecessary Hello messaging, which decrease network overhead and hidden energy consumption.

2.5 Implementation of Dymo Routing Protocol.

DYMO routing protocol is proposed by Perkins & Chakeres [13]. It is defined as the successor of AODV or ADOVv2 and it keeps on updating. DYMO operates similar to its predecessor i.e. AODV and does not add any extra modifications to the existing functionality. It is a purely reactive protocol in which routes are computed on demand. Unlike AODV, DYMO does not support unnecessary HELLO message transmission; also the operation is purely based on sequence number that is assigned to all the packets. It employs sequence numbers to ensure loop freedom. It also enables on demand, multi-hop unicast routing among the nodes in a network. The basic operations are route discovery and maintenance to obtain a valid path and also to avoid the existing obliterated routes from the routing table to reduce the packet dropping in case of any route break or node failure. The simulation has been performed with varying pause times and observed that DYMO being the successor of AODV performs better in all the terms.


In the proposed system, the behaviour of packet switching network is simulated using opnet modeler 14.5. This network may consist of four peripheral nodes to generate traffic while a central hub node that relays the traffic to the appropriate destination within the network. The performance of the network is measured by the end-to-end delay experienced by traffic on the network when delivering the packet. This proposed system consists of following modules,

> Creation of nodes,

> Defining the packet model, and link model,

> Creating the hub model,

> Creation of peripheral node model,

> Propogation of HELLO packets


With the advances in software and hardware architecture, mobile nodes can be created according to the requirements. Each node is equipped with a transmitter and receiver and they are said to be purpose-specific, autonomous and dynamic. This characteristic compares greatly with fixed wireless network as there is no master slave relationship that exists in ad hoc network. Mobile nodes rely on each other to the established communication, thus each node acts as router. Therefore, packets can travel directly or through some set of intermediate nodes to reach destination node.


The packets in this network contain a single field associated with the destination address in it. After the packet format has been created, it is specified as an attribute in a generator so that it can be formatted accordingly. The packet contains attributes such as name, type, size. Also, the set at creation attribute is changed to unset which may ensure that the field will not be assigned a default value when the packet is created.

Point-to-point links can be simplex (unidirectional) or duplex (bidirectional). Here in the proposed model, custom duplex link is used to connect transmitter-receiver pairs for end to end delivery. Link model is designed in such a way that it connects the hub and peripheral nodes and supports in packet transfer.


The hub node model consists of point-to-point transceivers for each peripheral node, and a process model to relay packets from receiver to the appropriate transmitter. The packet streams have a unique index which is an easiest method to set up a direct association between the hub process outgoing packet stream indices and the peripheral destination address values. In a more adaptive model, the hub process model is made to maintain a table for translating destination address value to transmitter stream indices. In this proposed system, a direct correspondence is made between designating addresses and packet stream indices.

Also, since each packet is associated with an interrupt, the hub process model may receive an interrupt whenever a packet arrives from a receiver. In the process model, the PK_ARRVL function compares the interrupt type of arrived packet with the predefined constant OPC_INTRPT_STRM, which is an stream interrupt. This type of interrupt for this model is good to safeguard against run-time transition errors.

The macro definition for PK_ARRVL function is:




The peripheral node model generates packet, assigns destination address, and processes received packets. It uses a user-defined process model to assign destination addresses to the generated packet and transmit them to the node's point-to-point transmitter. This process model retrieves the packet arriving from the point-to-point receiver and processes it to calculate the packet's end-to-end delay and the value is written to a global statistic so that it is accessible to multiple processes throughout the system.

In order to assign the destination address and calculation of end-to-end delay, the peripheral node process model needs two states:

> an initial state

> an idle state

The initial state is set to load the process model with a uniform PDF in a range of 0 to 3. address_dist = op_dist_load ("umform_mt", 0, 3);


Figure.3.1: Propogation of HELLO packets

To maintain connectivity, if a node has not sent any broadcast control message within a specified interval, a hello message is locally broadcasted to the every node in the network. For better result leads at least one hello message must be transmitted for every time period. If the node is unable to receive any hello message from a neighbor for several time intervals, it indicates that neighbor is no longer within transmission range, and connectivity has been lost. Two variables are responsible for the determination of connectivity using hello messages: Hello Interval and Allowed Hello Loss. Hello Interval- specifies the maximum time interval between the transmissions of hello messages. Allowed Hello Loss- specifies the maximum number of periods of hello interval to wait without receiving a hello message before detecting a loss of connectivity to a neighbor. The recommended value for HELLO INTERVAL is one second and for ALLOWED HELLO LOSS is two.


Processor : INTEL PENTIUM III, 4 or compatible (500 MHZ or Better)

RAM : 256 MB, 512 MB

Disk space : 400 MB

Display : 1024x768 or higher resolution, 256or more colors

Platform :Windows 2000,xp,vista

Application Development : Opnet modeler 14.5

OPNET stood for Optimized Network Engineering Tool. OPNET Modeler is a software tool for computer network modelling and simulation. Through this networking software, R&D process is accelerated resulting to easy analysis and design of communication networks, application, protocols, and devices. It offers the fastest discreet event simulation engine when compared with other networking solutions in the industry. It has an open interface for easy integration of libraries, external object files and other network simulators.


To examine the effect of the packet generation rate in an simulation environment for measuring the performance of the network, two simulation runs with different packet interarrival times are to be considered. End to end delay and link utilization is measured. In this simulation, the source node creates packets of a constant size. This setting, in combination with the fixed data rate at the point-to-point transmitters and receivers, may result in a fixed end-to-end delay for the packets.

However, if packets are sent more quickly to a transmitter, some of the packets will be delayed in the transmitter's queue. So, if the packet interarrival time is varied, the end-to-end delay will be varied and will be affected. To model this, configure two simulation runs with different packet interarrival times.

Fig.3: The time-averaged graph of energy utilization

End to end delay is calculated, when packets are transmitted and received and the result is shown below in linear graph.

Fig.4: Linear graph displaying End to End delay

The above linear graph doesnot show the end to end delay clearly. So, discrete graph is used for this is shown in fig.4.3

Fig.5: Discrete graph showing the End to End delay


A mobile ad hoc network (MANET) consists of one or more autonomous mobile nodes, each of which communicates directly or indirectly with the neighbor nodes within its radio range. The field of MANET is rapidly growing due to varied advantage and applications. Energy efficiency is a challenge faced especially in designing a routing protocol. In the proposed system, packet switching networks is implemented for transmitting and receiving the packets, finally calculate the delay.

A single routing protocol is hard to satisfy all requirements. i.e., one routing protocol cannot be a solution for all energy efficient protocol that designed to provide the maximum possible requirements, according to certain required scenarios.

In future, Ant Routing Protocol can be used to find the optimal path, also Efficient Energy Aware Routing Protocol (EEARP) can be proposed to increase the network lifetime of MANET. AlsoUsing a mini-max formulation, EEARP selects the path that has the largest packet capacity at the smallest residual packet transmission capacity. The proposed scheme may reduce the energy consumption to some extent and decreases the mean delay, while achieving a good packet delivery ratio.


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