Performance Analysis Of Routing Protocols In Wireless Sensor

Published Date: 02 Nov 2017

ABSTRACT

The Recent advances in wireless Sensor Networks which have led to many new protocols specifically designed for sensor networks where energy awareness is an essential consideration. It is necessary to identify the performance challenges of Wireless Sensor Networks and analyze their impact on the performance of routing protocols. It surveys recent routing protocols for sensor networks and presents a classification for the various approaches pursued. Due to the limited processing power, only a finite power available to each sensor node. Routing protocols in ad hoc networks has received wide interest in the past years due to the fact that existing internet routing protocols were designed to support fixed infrastructure and their properties are unsuitable for mobile ad hoc networks. Routing algorithms must also be robust to failures should provide a low power consumption. The performance of these protocols are compared by the simulation parameters like packet delivery ratio, energy consumption etc. Wireless links suffer transient periods of disconnection. Such transient failures occur frequently due to system errors or external stimuli. Aggressive behavior to heal faults that are manifestations of transient errors can cause network instability. Thus, fine-tuning of protocol configuration parameters is essential to ensure an acceptable level of fidelity.

Keywords: Energy consumption, Packet delivery ratio, Packet delay, AODV, DSR.

INTRODUCTION

As the popularity of the laptops, cell phones, PDA’s, GPS devices, RFID and intelligent electronics have become cheaper and more pervasive in daily life. A wireless sensor node consists of sensing, computing, communicating, actuating, and power consuming components. With state-of-art, low power circuit and networking can last up to three years with a low duty cycle working mode. Sensor nodes are responsible for self-organizing an appropriate network infrastructure, often with multi-hop connections between sensor nodes. Sensor network routing protocols must ensure the stability of the network infrastructure under varying network dynamics. Sensor network requirements were low power consumption, support multi-hop wireless communication, self configuring, small physical size, can reprogram over network. Location and positioning information can also be obtained through the global positioning systems (GPS) or local positioning algorithms. This information can be gathered from the network and appropriately processed to construct a global view of the monitoring objects.

II. WIRELESS SENSOR NETWORK

A wireless sensor network (WSN) consists of spatially distributed autonomous sensors to monitor physical or environmental conditions, such as temperature, sound, pressure, etc. and to cooperatively pass their data through the network to a main location. The more modern networks are bi-directional, also enabling control of sensor activity.

The requirements for motes are extensive. They must be small, energy efficient, multifunctional, and wireless. Collections of motes communicate with each other to reach a common goal. The design of sensor network is a challenge because of influencing factors such as fault tolerance, stability, production cost, operating environment, network topology, hardware constraints, transmission media, power consumption and others have to be considered.

The performance of the network is then measured based on quantifiable parameters called performance metrics. This however varies according to need and the nature of sensor nodes. The cost of sensor nodes is similarly variable, ranging from a few to hundreds of dollars, depending on the complexity of the individual sensor nodes. Size and cost constraints on sensor nodes result in corresponding constraints on resources such as energy, memory, computational speed and communications bandwidth.

Fig II.1 Sensor nodes

The challenges in the hierarchy of: detecting the relevant quantities, monitoring and collecting the data, assessing and evaluating the information, formulating meaningful user displays, and performing decision-making and alarm functions are enormous.

III. ROUTING PROTOCOL

Routing

Routing is a process of determining a path between source and destination upon request of data transmission. A  routing protocol specifies how routers communicate with each other, disseminating information that enables them to select routes between any two nodes on a computer network, the choice of the route being done by routing algorithms. Each router has a priori knowledge only of networks attached to it directly. A routing protocol shares this information first among immediate neighbors, and then throughout the network. This way, routers gain knowledge of the topology of the network. 

The implementation of routing tables gives the solution. This contains the lists of node option for any given packet destination. Routing table is the task of the routing algorithm along with the help of the routing protocol for their construction and maintenance.

Routing algorithm

Routing algorithms calculate the best path per destination in a distance vector or link-state basis. In a distance vector protocol, optimality is computed incrementally along a path. Sensors calculate routes locally, based on their current, partial network state. In link-state protocols, on the other hand, every sensor contributes to establish a replicated distributed database of the network topology. Then, sensors run a shortest path algorithm (e.g. Dijkstra’s algorithm) over this topology database instance.

Management traffic is often overlooked; sensors may also accept re-configuration commands, software updates, or complete binary images from an authority external to the network. Routing protocols for Mobile ad hoc networks can be broadly classified into two main categories:

• Proactive or table-driven routing protocols

• Reactive or on-demand routing protocols.

Table driven routing protocols (Proactive)

In proactive or table-driven routing protocols, each node continuously maintains up-to-date routes to every other node in the network. Routing information is periodically transmitted throughout the network in order to maintain routing table consistency. Thus, if a route has already existed before traffic arrives, transmission occurs without delay. Otherwise, traffic packets should wait in queue until the node receives routing information corresponding to its destination. Certain proactive routing protocols are Destination Sequenced Distance Vector (DSDV), Wireless Routing Protocol (WRP), Global State Routing (GSR) and Cluster head Gateway Switch Routing (CGSR).

On-demand routing protocols (Reactive)

In contrast to proactive approach, in reactive or on demand protocols, a node initiates a route discovery throughout the network, only when it wants to send packets to its destination. For this purpose, a node initiates a route discovery process through the network. This process is completed once a route is determined or all possible permutations have been examined.

Once a route has been established, it is maintained by a route maintenance process until either the destination becomes inaccessible along every path from the source or until the route is no longer desired. In reactive schemes, nodes maintain the routes to active destinations.

A route search is needed for every unknown destination. Therefore, theoretically the communication overhead is reduced at expense of delay due to route research. Some reactive protocols are Cluster Based Routing Protocol (CBRP), Ad hoc On-Demand Distance Vector (AODV), Dynamic Source Routing (DSR), Temporally Ordered Routing Algorithm (TORA), Associativity Based Routing (ABR), Signal Stability Routing (SSR) and Location Aided Routing (LAR).

Adhoc On-demand Distance Vector (AODV)

The AODV protocol reduces control traffic by originating path requests on demand. It does not broadcast packets blindly; instead, reply packets are unicast during path establishment. Liveness monitoring of active neighbors uses stateless hello messages. Upon failure, it generates an error message to notify upstream sensors that use the broken path. There are path discovery, establishment, and monitoring process of the protocol.

Path discovery: An event or alarm will trigger a route request only if a valid path to the sink doesn’t exist. Paths expire either implicitly, e.g. routing state timeouts, or explicitly, e.g. error packets sent. Sensors buffer their data packets until they receive a reply.

The AODV protocol uses implicit acknowledgements to determine bidirectionality between any pair of sensors. If a sensor marks, or blacklists, a link as unsteady, it ignores it in the path discovery process.

Fig 4.1 AODV Route Discovery

Path establishment: Upon receipt of a request, sinks establish a path in reverse: they propagate their reply using the previous sensor as the next relay to the originator. A sink receives more than one request per source. Usually, the first request traverses the fastest path. The sink can reinforce multiple paths to an originator. In turn, it can discard, use, or store these paths, based on the collection strategy. Reply messages are unicast, rather than multicast. Sensors can generate a gratuitous reply, if they already maintain an active path to the destination.

Path monitoring: Active sensors, i.e. sensors that participate in an active path, assert connectivity by sending periodic hello messages. The rest of the network remains silent. If within a refresh time interval a sensor doesn’t receive a routing state update, is assumes a failure and generates a route error packet. A failure can affect one or more data flows. Route error packets invalidate these affected paths in neighbor sensors. In turn, they can iterate the error message until all affected originators reissue a request. However, given sensor constraints, it is best to repair paths locally. The main advantage of this protocol is having routes established on demand and that destination sequence numbers are applied for find the latest route to the destination. The connection setup delay is lower.

Dynamic Source Routing Protocol

Dynamic Source Routing (DSR) is a routing protocol for wireless mesh networks. It is similar to AODV in that it forms a route on-demand when a transmitting computer requests one. However, it uses source routing instead of relying on the routing table at each intermediate device.

Determining source routes requires accumulating the address of each device between the source and destination during route discovery. The accumulated path information is cached by nodes processing the route discovery packets. The learned paths are used to route packets.

Route Discovery and Route Maintenance

This protocol is truly based on source routing whereby all the routing information is maintained (continually updated) at mobile nodes. It has only two major phases, which are Route Discovery and Route Maintenance. Route Reply would only be generated if the message has reached the intended destination node. To return the Route Reply, the destination node must have a route to the source node.

Route request and route reply

The basic approach of this protocol during the route construction phase is to establish a route by flooding Route Request packets in the network. The destination node, on receiving a Route Request packet, responds by sending a Route Reply packet back to the source, which carries the route traversed by the Route Request packet received.

IV. APPLICATIONS OF SENSOR NETWORK

MILITARY APPLICATION

Because most of the elemental knowledge of sensor networks is basic on the defense application at the beginning, especially two important programs the Distributed Sensor Networks (DSN) and the Sensor Information Technology (SenIT) form the Defense Advanced Research Project Agency (DARPA), sensor networks are applied very successfully in the military sensing..

AREA MONITORING

Area monitoring is a common application of WSNs. In area monitoring, the WSN is deployed over a region where some phenomenon is to be monitored. FOREST FIRE DETECTION

A network of Sensor Nodes can be installed in a forest to detect when a fire has started. The nodes can be equipped with sensors to measure temperature, humidity and gases which are produced by fire in the trees or vegetation. The early detection is crucial for a successful action of the firefighters; thanks to Wireless Sensor Networks, the fire brigade will be able to know when a fire is started and how it is spreading.

AIR POLLUTION MONITORING

Wireless sensor networks have been deployed in several cities to monitor the concentration of dangerous gases for citizens. These can take advantage of the ad-hoc wireless links rather than wired installations, which also make them more mobile for testing readings in different areas. There are various architectures that can be used for such applications as well as different kinds of data analysis and data mining that can be conducted.

LANDSLIDE DETECTION

A landslide detection system makes use of a wireless sensor network to detect the slight movements of soil and changes in various parameters that may occur before or during a landslide. And through the data gathered it may be possible to know the occurrence of landslides long before it actually happens.

WASTEWATER MONITORING

There are many opportunities for using wireless sensor networks within the water/wastewater industries. Facilities not wired for power or data transmission can be monitored using industrial wireless I/O devices and sensors powered using solar panels or battery packs and also used in pollution control board.

ENVIRONMENTAL APPLICATIONS

Nowadays sensor networks are also widely applied in habitat monitoring, agriculture research, fire detection and traffic control. Because there is no interruption to the environment, sensor networks in environmental area is not that strict as in battlefield.

V. SOFTWARE DESCRIPTION

ns-2.35

ns-2.35 stands for Network Simulator version 2.35. It is a discrete event simulator for networking research. It works at packet level and provide substantial support to simulate bunch of protocols like TCP, UDP, FTP, HTTP and DSR and it is primarily Unix based. ns-2 is a standard experiment environment in research community. ns2 is basically an OTcl interpreter with network simulation object libraries. Very simple syntax and easy integration with other languages.

Characteristics are

fast development

provide graphic interface

compatible with many platforms

flexible for integration

easy to use

Performance metrics:

Packet delivery ratio

=

Total number of data packets successfully delivered x 100

Total number of data packets sent

∑

Individual data packet latency

Total number of data packets delivered

Packet

Latency =

VI. SIMULATION RESULTS

Parameter

Value

Simulator

Ns 2.35

Simulation time

70 sec

Simulation area

500 x 500

number of mobile nodes

10

Node movement model

Random waypoint

Traffic type

CBR (UDP)

Data payload

Bytes/packet

Table VI.1 Simulation parameters

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VI.2 Aodv protocol

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VI.3 Dsr protocol

VII. CONCLUSION

Since it is a very arduous and challenging task to design a perfect routing layer protocol for WSNs, in this paper we examined the results of employing traditional ad hoc routing protocols in WSNs. As it can be seen from our simulation results, the DSR protocol is not a bad choice for the WSNs applications where reliability and energy efficiency are crucial. AODV

is the most primary protocol used in various wireless sensor network applications so as to get rid from the problem of energy consumption and the packet delivery ratio The problem is that the protocol has to solve some sophisticated problems like data redundancy, energy efficiency, and collisions between data without being sophisticated itself, because of the limitations in memory, computing power and energy resources. So applying an approximation algorithm for routing may be an optimal solution for the WSNs.

VIII. FUTURE ENHANCEMENT

So far the routing protocols such as AODV and DSR in wireless sensor networks were simulated based on the performance metrics such as packet lost, packet delivery ratio. In future the performance metric energy consumption is to be taken in order to determine the overall performance of the protocols with respect to the sensor networking applications.

IX. REFERENCES

[1] G. Sriram, D. Srinivasa Rao "Performance Analysis of WRP, DSR and AODV in Wireless Sensor Networks" for International Journal of Advanced Research in Computer Science and Software Engineering Volume 2, Issue 6, June 2012

[2] V. Vasanthi, P.Nagarajan, B.Bharathi and Dr.M.Hemalatha "A Perspective Analysis of routing protocols in wireless sensor network" (IJCSE) International Journal on Computer Science and Engineering Vol. 02, No. 08, 2010, 2511-2518.

[3] David Culler, Deborah Estrin, Mani Srivastava "Overview of sensor networks" Published by the IEEE Computer Society, August 2010.

[4] Alexandros Koliousis and Joseph Sventek "Proactive vs. reactive routing for wireless sensor networks" Department of Computing Science, University of Glasgow.

[5] Dr. Yingu Li fall GSU by Robert Persaud "LEACH protocol for wireless sensor network" 2010.

[6]Macro Zennaro ICTP Trieste Italy "Introduction to wireless sensor networks" Jan 2009

[7] http://www.isi.edu/nsnam/ns/nstutorial/inde x.html

[8] http://www.tcl.tk/software/tcltk