Energy Efficient Approach in Wireless Sensor Networks

Transcription

1 Energy Efficient Approach in Wireless Sensor Networks Vandana Rani ECE Department Sudesh Nandal ECE Department Sandeep Dahiya ECEDepartment Abstract: A WSN consists of sensor nodes with limited power supply and constrained computational and transmission capability. It is essential to operate the sensor network for a long period of time in an energy efficient manner for gathering sensed information. Due to the limited transmission and computational ability, and high density of sensor nodes, data packets forwarding takes place in multi-hop data transmission. Therefore routing in wireless sensor networks is a significant area of investigation in the past few years. The sensor nodes run on nonrechargeable batteries, so besides the efficient routing, the network should be efficient in energy with efficient utilization of the resources and hence this is an important research concern. Keywords: WSN, Routing, Energy Efficiency, LEACH, TEEN. I. INTRODUCTION A network is a set of devices (often nodes) joined by communication links. A node can be a computer, printer, or any other device that can send and receive data created by other nodes on the network [1]. Wireless sensor network consisting of various small wireless sensor nodes that have transmission devices which require some amount of energy to transmit data to other nodes. A WSN is a deployment of massive numbers of small, inexpensive, self powering devices that has the power of sensing, computing, and communicating with other devices for the purpose of gathering local information to take comprehensive decisions about physical surroundings [2]. WSN (Wireless Sensor Network) consists of individual nodes that are capable of interacting with their surroundings by sensing or controlling physical parameter; these nodes have to perform together in order to complete their jobs as usual, a single node is unable to do that and they use wireless communication to facilitate this association. WSN can be used in many applications like health applications, environmental monitoring, military surveillance, smart homes and habitat monitoring. WSN consist of sensor nodes, clusters and base stations. The sensor nodes are deployed in wireless sensor network in environment and then these nodes are connected to a base station and the base station can be used to process the sensed data that come from the sensors [3]. WSN consist of nodes that are used to collect valuable information from the sensor. It is crucial to control the sensor network for a long period of time in an energy efficient manner for gathering sensed information. Figure 1: Configuration of WSN Figure 1 shows the basic architecture of smart sensors. Sensing unit does the work of identifying the changes in parameters of the system (network) and signal conditioning where the smoothing of analog electrical signals takes place before it gets converted to digital signal. The resulting digital signal is given the input to the application algorithm or processing unit and then cached in the memory. The communication with other sensors or base station (BS) is achieved with the help of transreceivers which may act as an internet gateway in WSN [4]. RES Publication 2012 Page 44

2 A. Networks Classification of sensor network on basis of their mode of functioning and the type of target application are: I) Proactive Networks Nodes in this network periodically switch ON their sensors and sender performs the task of sensing the environment and sends the data of interest. Thus, they provide a snapshot of the relevant parameters at regular intervals. These types of networks well suited for applications requiring periodic monitoring of data. Some known instances of this kind are the LEACH protocol and some improvement of LEACH protocol [5]. II) Reactive Networks In such type of networks, the nodes react immediately to sudden and drastic changes in the value of a sensed attribute. These types of networks are well suited for time critical applications. Recent advances in wireless sensor networks have too many new protocols particularly designed for sensor networks where energy awareness is an essential consideration. But methods like Direct Communication and Minimum Transmission Energy do not guarantee balanced energy distribution among the sensing nodes [6]. In Direct Communication Protocol, each sensor node transmits information directly to the base station, despite the concerns of distance. Due to this, the nodes farthest from the BS are the ones to die first. On the other hand, in case of Minimum Transmission Energy routing protocol, data is transmitted through intermediate nodes. Thus each node starts acting as a router for data of other nodes in addition to sensing the environment. Nodes closest to the BS are the first to die in MTE routing. So far, cluster-based technique is one of the approaches which have gained success in increasing the lifetime and stability of the entire sensor networks. We classified most important energy efficient routing algorithms based on a variety of clustering attributes like forming clusters and data gathering process [7]. III) Hybrid Networks The nodes in these type of networks not only react to critical-time conditions, but also give a general picture of the network at cyclic intervals in a very energy proficient way. With the help of these networks, users can request present, past, and future data from the network in the form of historical, one-time and persistent queries respectively. B. Classification of Sensor C. Energy Efficient WSN Protocols Protocols for Sensor networks must be designed in such a way that results in the efficient use of limited power existing at the sensor nodes. Routing in WSN is quite challenging due to its inherent limitations and basic features that differentiate WSN from other wireless networks [8]. There are various ways in which routing in WSNs varies from routing in fixed networks. There is no infrastructure, wireless links are untrustworthy, chances of failure of sensor nodes are more and routing protocols have to meet strict energy reduction needs [9]. Many routing techniques used in WSNs were developed for general applications in wireless networks. Clustering is an energy-efficient communication protocol that can be used by the sensors to report their sensed data to the sink. A network is composed of several clusters of sensors. The management of each clump is headed by a particular node, called cluster head, which is responsible for directing the transmission of data of all sensors in its clump [10]. I) Low-energy adaptive clustering hierarchy (LEACH) LEACH [11] is the first and most popular energyefficient hierarchical clustering algorithm for WSNs that was suggested for dropping power intake. In LEACH, the clustering task is rotated among the nodes, based on interval. Each cluster head (CH) performs direct communication to forward the data to the base station (BS). It uses clusters approach to increase the life of the WSN. LEACH is based on an aggregation (or fusion) technique that does the task of aggregation of the original data into a lesser size of data that carry only significant information to all individual sensors [12]. LEACH protocol partitions the network into numerous clusters of sensors, which are constructed by using localized synchronization and control not only to lessen the extent of data that are transmitted to the sink, but also to make routing and distribution of data more scalable and vigorous. Instead of selecting in stationary manner, LEACH uses a randomize rotation of high-energy CH position, to provide a chance to all sensors to act as CHs and avoid the battery exhaustion of an individual sensor and dying rapidly [13]. The operation of LEACH is divided into rounds each of which has two phases namely (i) a setup phase for the association of the network into clusters, CH advertisement, and creation of transmission schedule and (ii) a steady-state phase which consists of phases like aggregation of data, compression of data and transmission to the sink. LEACH is completely distributed and therefore, it does not require overall knowledge of the network. It decreases energy consumption by (a) minimizing the communication cost between sensors and their CHs and RES Publication 2012 Page 45

3 routing where each node is capable of transmitting directly to the cluster-head and the sink. Therefore, it is not applicable to networks deployed in large provinces. Moreover, the idea of dynamic clustering brings extra overhead, e.g. head changes, advertisements etc., which may lessen the gain in energy consumption. While LEACH helps the sensors within their cluster dispel their energy gradually, the cluster heads consume a larger amount of energy when they are located farther away from the sink. Also, the termination of LEACH clustering takes place in a finite number of iterations, but does not guarantee good distribution of cluster heads and assumes even energy depletion for CHs [14]. II) Threshold Sensitive Energy Efficient Sensor Network Protocol (TEEN) TEEN is a Hierarchical clustering protocol, which forms clusters from sensor groups with each headed by a CH. The sensors within a cluster report their sensed data to their head. The CH transmits collected data to next level CH until the data reaches the sink [15]. Thus, the sensor network design in TEEN consists of hierarchical grouping where the nodes which are closer to each other form clusters and this procedure proceeds on the next level until the BS (sink) is reached. TEEN proves to be helpful for applications where the users can have power over a trade-off between energy efficiency, data precision, and response time vigorously [16]. TEEN makes use of a data-centric method with hierarchical method. Important features of TEEN comprise of its suitability for time critical sensing applications. Also, as message communication consumes more energy than in sensing data, so this scheme requires less energy than the proactive networks. TEEN is not appropriate for sensing applications which require periodic reports since the user may not get any data if the point of threshold is not reached [17]. II. IMPLEMENTATION & RESULTS There are several simulators available like MATLAB, OMNET++, QualNet, OPNET and NS2 to check the performance of protocols. In present study, MATLAB is used with the integrated model of LEACH protocol. A. Performance Metrics There are various criteria on the basis of which the performance of any system can be evaluated. These kinds of parameters are known as performance metrics [18]. The parameters used to evaluate the clustering protocols are lifetime, number of nodes which are alive and the number of packets of data which are to be received at base station. The performance of the protocols can be compared with the help of three metrices. The following performance metrics are considered for evaluation of network: 1) Average energy dissipated: This metric tells about the average energy dissipated per node over the given span of time in the network as it performs various functions such as sending and receiving data, sensing and data aggregation etc. 2) Total number of nodes alive: This metric gives an indication of the overall lifetime of the network. Moreover, it gives an idea of the area covered by the network in a given time. We take into consideration various parameters used to implement these protocols. A common parameter which can be taken into consideration for both the protocols is the attribute to that must be sensed, which is the temperature. 3) Data Packets received at base station: It is defined as the total number of data packets or messages that are received by the BS. This measure varies linearly for all protocols. B. Design Workflow In order to build a network properly, following steps must be followed, starting from creating the network models, secondly, choose data and statistics to be collected and then run the simulation, finally, view and analyse the results. Figure 2 illustrates the simulation design s workflow. Figure 2: Simulation Design Workflow C. Architecture Algorithm The methodology adopted in the modeling and simulation is presented in the architecture algorithmic diagram as shown in Figure 3. To evaluate the performance of protocol, we have implemented it on the MATLAB simulator with the integrated model of advance leach protocol. Energy is most significant parameter in cluster formation. Figure 4 shows the initial nodes distribution in LEACH method. Figure 5 shows sensors that are alive (dotted circles) and dead sensors (dots) after 100 rounds (of data transmission) in RES Publication 2012 Page 46

4 LEACH algorithm. Position of sensor nodes and formation of cluster head is shown in Figure 5. Figure 6 describes the average energy of each node in the specified round number after the transmission has taken place through LEACH algorithm. The performance of LEACH a in the network system is presented in Figure 6. The increase in the network size, results in increasing the number of hops for transmission of data. Start Name First Scenario Figure 4: Nodes Creation Draw Model Configure Model Objects Select Needed Statistics Name another Scenario In another scenario is needed? No Yes Configure Simulation Figure 5: Node Energy Shifting in Cluster Run Simulation View & analyze results Document Results End Figure 3: Architecture Algorithmic Diagram Figure 6: Output III. CONCLUSION The ultimate aim of a routing protocol design is to extend the lifetime of the network by keeping the sensors alive for a RES Publication 2012 Page 47

5 maximum time. Since energy spent on transmission is very high as compared to that of sensing. The routing algorithm has been designed to reduce energy consumption for transmitting the data. In present paper, different routing protocols and algorithms based on hierarchical routing, grouping or clustering of sensors, location information, network heterogeneity and QoS (Quality of service) have been utilized. The result shows that LEACH has better performance as compared to other algorithms because it increases the lifetime, stability of the network and quite efficient in terms of energy consumption. The future work can be plan to design a heterogeneous network where it can have several Base-Stations that communicate together and use DEEC, SEP, APTEEN protocol which selects multiple Cluster Heads using fuzzy logic and uses these Cluster Heads to transmit data to the Base Stations. REFERENCES [1] Behrouz A. Forouzan, Data Communications and Networking, Tata McGraw Hill, Fourth Edition, [2] R.A.Roseline, Dr.P.Sumathi, Energy Efficient Routing Protocols and Algorithms for Wireless Sensor Networks A Survey,Global Journal of Computer Science and Technology,Volume 11, Issue 21, December [3] Anuj Kumar, WiseMAC Protocol for Wireless Sensor Network-An Energy-Efficient Protocol, Department of Electronics & Communication Engineering, National Institute of Technology Rourkela, [4] Gaurav Sharma, Routing In Wireless Sensor Networks, Computer Science And Engineering Department Thapar University Patiala, [5] Uday B. Desai, B. N. Jain, S. N. Merchant, Wireless Sensor Networks: Technology Roadmap, A Project supported by Department of Information Technology, Ministry of Information and Communication Technology, India. [6] Arati Manjeshwar and Dharma P. Agrawal, TEEN: A Routing Protocol for Enhanced Efficiency in Wireless Sensor Networks [2012] [7] C.Y. Chong and S.P. Kumar, Sensor Networks: Evolution, Opportunities, and Challenges, in Proceedings of the IEEE, pp , Vol. 91, No. 8, Aug [8] Karp and H. T. Kung, GPSR: greedy perimeter stateless routing for wireless networks, in Mobile Computing and Networking, 2000, pp [9] S. Misra et al., Guide to Wireless Sensor Networks, Computer Communications and Networks, Springer-Verlag London Limited [10] Stephan Olariu, Information assurance in wireless sensor networks, Sensornetwork research group, Old Dominion University. [11] W.R. Heinzelman, A. Chandrakasan, and H. Balakrishnan, Energy-efficient Communication Protocol for Wireless Microsensor Networks, in IEEE Computer Society Proceedings of the Thirty Third Hawaii International Conference on System Sciences (HICSS), Washington, DC, USA, Jan. 2000, vol. 8, pp [12] W.R. Heinzelman, A. Chandrakasan, and H. Balakrishnan, An Application-Specific Protocol Architecture for Wireless Microsensor Networks in IEEE Tmnsactions on Wireless Communications (October 2002), vol. 1(4), pp [13] Brain P. Crow, IndraWidjaja, JeonGeun Kim and Prescott T. Sakai, IEEE Wireless Local Area Networks, IEEE Communication Magazine, Vol. 35, Sep [14] Jose A Gutirez et al. IEEE : A Developing for Low Rate Wireless Personal Area Network. [15] A. Manjeshwar and D. P. Agrawal, TEEN: A Protocol for Enhanced Efficiency in Wireless Sensor Networks, in the Proceedings of the 1st International Workshop on Parallel and Distributed Computing Issues in Wireless Networks and Mobile Computing, San Francisco, CA, April [16] W. Lou, An Efficient N-to-1 Multipath Routing Protocol in Wireless Sensor Networks, Proceedings of IEEE MASS 05, Washington DC, Nov. 2005, pp [17] ZiboudaAliouat, SaadHarous, An Efficient Clustering Protocol Increasing Wireless Sensor Networks Life Time [2012]. [18] Kurose-Ross, Performance Measurements and Metrics, ITN, RES Publication 2012 Page 48