28-01-2013, 01:04 PM
Evaluation of AODV and DSR Routing Protocols of Wireless Sensor Networks for Monitoring Applications
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ABSTRACT
Deployment of sensor networks are increasing either manually or randomly to monitor physical environments in different applications such as military, agriculture, medical transport, industry etc. In monitoring of physical environments, the most important application of wireless sensor network is monitoring of critical conditions. The most important in monitoring application like critical condition is the sensing of information during emergency state from the physical environment where the network of sensors is deployed.
In order to respond within a fraction of seconds in case of critical conditions like explosions, fire and leaking of toxic gases, there must be a system which should be fast enough. A big challenge to sensor networks is a fast, reliable and fault tolerant channel during emergency conditions to sink (base station) that receives the events.
The main focus of this thesis is to discuss and evaluate the performance of two different routing protocols like Ad hoc On Demand Distance Vector (AODV) and Dynamic Source Routing (DSR) for monitoring of critical conditions with the help of important metrics like throughput and end-to-end delay in different scenarios. On the basis of results derived from simulation a conclusion is drawn on the comparison between these two different routing protocols with parameters like end-to-end delay and throughput.
INTRODUCTION
The advancements in wireless communication technologies enabled large scale wireless sensor networks (WSNs) deployment [30]. Due to the feature of ease of deployment of sensor nodes, wireless sensor networks (WSNs) have a vast range of applications such as monitoring of environment and rescue missions [31]. Wireless sensor network is composed of large number of sensor nodes. The event is sensed by the low power sensor node deployed in neighborhood and the sensed information is transmitted to a remote processing unit or base station [21].
To deliver crucial information from the environment in real time it is impossible with wired sensor networks whereas wireless sensor networks are used for data collection and processing in real time from environment [21]. The ambient conditions in the environment are measured by sensors and then measurements are processed in order to assess the situation accurately in area around the sensors. Over a large geographical area large numbers of sensor nodes are deployed for accurate monitoring. Due to the limited radio range of the sensor nodes the increase in network size increases coverage of area but data transmission i.e. communication to the base station (BS) is made possible with the help of intermediate nodes.
Depending on the different applications of wireless sensor networks they are either deployed manually or randomly. After being deployed either in a manual or random fashion, the sensor nodes self-organize themselves and start communication by sending the sensed data. These sensor networks are deployed at a great pace in the current world. Access to wireless sensor networks through internet is expected within 10-15 years [1]. There is an interesting unlimited potential in this wireless technology with various application areas along with crisis management, transportation, military, medical, natural disaster, seismic sensing and environmental. There are two main applications of wireless sensor networks which can be categorized as: monitoring and tracking.
GUIDELINE OF THESIS:
There are five chapters presented in this thesis work. In next chapter, the architecture, components and applications about WSN is covered. Also the comparison between MANETs and WSN is done in the next chapter.
The third chapter of the thesis work covers the study of the routing protocols and main design issues of WSNs. A detailed explanation of the different types of protocols including their architecture and classification required for the thesis work is also presented.
The simulation tool, network design is explained in the fourth chapter. The two routing protocols AODV and DSR are implemented in the OPNET simulator.
In final chapter the analysis of the results is performed on the simulator by comparison of the selected routing protocols in terms of delay and throughput and observations form results are derived in order to determine which routing protocol works better in different scenarios.
RESEARCH WORK:
In an evaluation of three routing protocols of WSN namely probabilistic geographic routing protocol (PGR), beacon vector, routing protocol (BVR) and flooding protocol (FP) using prowler simulator to determine which one is efficient for scalability through several metrics which are throughput, latency, energy consumption and delay, it was concluded that BVR is most efficient for scalability [17].
AODV, a reactive routing protocol performance is improved by fixing expiry time and analyzing it in QualNet 4.5. On basis of results derived from simulation the shortest routing path is ensured based on IEEE 802.11 and IEEE 802.15.4. This routing protocol is good in case of wireless sensor networks because of frequent movement [8].
The differences in AODV, CBRP, PAODV, DSDV and DSR routing protocols is presented by comparing the size of ad hoc networks, load and mobility. The authors concluded that AODV shows the shortest end-to-end delay and throughput in DSR and CBRP is very high. Routing overhead in DSR is higher than CBRP instead of less number of route request packets, while largest overhead is shown by AODV. The original AODV routing protocol is outperformed by preemptive routing protocol [9].
SENSOR NODE ARCHITECTURE:
A wireless sensor node is capable of gathering information from surroundings, processing and transmitting required data to other nodes in network. The sensed signal from the environment is analog which is then digitized by analog-to-digital converter which is then sent to microcontroller for further processing. The block diagram of a sensing node is shown in figure [2]. While designing the hardware of any sensor node the main feature in consideration is the reduction of power consumption by the node. Most of the power consumption is by the radio subsystem of the sensing node [33]. So the sending of required data over radio network is advantageous. An algorithm is required to program a sensing node so that it knows when to send data after event sensing in event driven based sensor model. Another important factor is the reduction of power consumption by the sensor which should be in consideration as well. During the designing of hardware of sensing node microprocessor should be allowed to control the power to different parts such as sensor, sensor signal conditioner and radio.