International Journal of Engineering Trends and Technology (IJETT) – Volume 33 Number 4- March 2016 Study of Various Approaches for Minimizing Energy Consumption in Wireless Sensor Network Palkin Sharma1, Sonia Goyal2 1 Department of ECE, Punjabi University, Patiala, Punjab, INDIA Department of ECE, Punjabi University, Patiala, Punjab, INDIA 2 Abstract- With the advancement in technology, the application fields of Wireless Sensor Networks (WSN) are also increasing. Sensors are the devices that are used to detect or monitor an object or area of interest and communicate the data collected to other nodes in the network. Wireless Sensor Networks are deployed for battlefield surveillance, tracking, area, health and environmental monitoring. These applications require a network of number of sensor nodes. The nodes are battery powered, and this limited energy source becomes the major limitation for wireless sensor network because network will be operational as long as the nodes in the network are having sufficient energy for the entire process. This paper reviews different approaches that contributed towards the extended network lifetime and increased energy efficiency in WSN. Keywords- Energy consumption, limitation, network lifetime, optimum, wireless sensor networks I. INTRODUCTION Wireless sensor network consists of large number of sensor nodes. These sensor nodes have the capability of sensing the environment, collecting data and after processing the data, it is sent to the sink or base station using single hp or multi hop communication. Wireless Sensor Networks (WSN) consists of various types of nodes such as infrared, acoustic, radar, seismic, thermal, biological, etc. so thus they have wide application range [1]. The sensor nodes used in the network are powered by batteries so when they are deployed in hazardous areas, battery replacement becomes impractical. The node energy thus becomes an important issue as it directly affects the duration of network. Generally the network lifetime is defined as duration until any sensor node dies [2]. In order to extend the network lifetime with limited battery power, energy conservation is required. The various sources of energy consumption can be idle listening (listening to an idle channel), collision (more than one packet is received), overhearing (receiving packet destined to other nodes), and many more [3]. Among various sources of energy consumption, communication phase ISSN: 2231-5381 requires the most of energy. So efficient use of energy has become an important requirement in the WSN and gained much attention of researchers in recent time. In order to increase the energy efficiency, hierarchical network architecture or clustered architecture is considered as a solution [4]. Nodes are basically combined into clusters and for every cluster a selected node called as cluster head collects the data and transmits to the sink or base station. Various clustering algorithms have been developed in recent times in which different parameters have been considered in order to increase the network lifetime. The network requires deployment of nodes, clustering and then data transmission to the base station. Increasing energy efficiency approaches have been adopted at node deployment phase, data aggregation and clustering phase. Low Energy Adaptive Clustering Hierarchy (LEACH) is the common and popular clustering protocol to achieve the load balancing. Other protocols are Energy Efficient Clustering Scheme (EECS) [5], Hybrid Energy Efficient Distributed Clustering (HEED), Stable Election Protocol (SEP) [6]. The clustering schemes form hierarchical network with cluster heads at the higher level and member nodes at the lower level. Various approaches have been adopted during node deployment and data aggregation as these can also contribute to energy conservation. Each of the approach has considered one or more parameter to improve the performance of the wireless sensor network. For the purpose of sensing the area of interest, nodes are deployed in the desired area randomly or deterministically [7]. Node deployment in an efficient way can also lead to energy conservation it the network. Clustering has been considered as an energy efficient approach so nodes are divided into clusters and cluster heads are selected based on various parameters. The parameters will contribute towards the improvement in the working of the network. Cluster heads collect the data from nodes and aggregate the data before sending it to sink or base http://www.ijettjournal.org Page 180 International Journal of Engineering Trends and Technology (IJETT) – Volume 33 Number 4- March 2016 station. Aggregation of data also consumes energy of the nodes, especially the cluster heads, so different mechanisms have been proposed for data aggregation also [8]. The transmission of data packets of L bits over a distance d also consumes energy given as : is the cross- over distance, is energy dissipation rate to run transmit amplifier when d< , l is packet size, is energy dissipation rate to run transmit amplifier when d > , is the energy being dissipated to run the transmitter or receiver circuitry [10]. E = L* + L* * if d<< (1) A new improved barrier coverage algorithm increased =L* + L* * if d>> the network lifetime upto 34.63% by introducing four (2) procedures BEGIN, ACTIVE, IDEAL and CHECK. The amount of energy required to receive a packet of Energy consumption in proposed method is 10.21 J L bits is given by: which is very less [11]. Various parameters of node deployment like coverage area, number of nodes also E =L* affect Quality of Service (QoS) of the network. (3) Considering these parameters, improvement in QoS is Where is the energy being dissipated to run the achieved in [12]. transmitter or receiver circuitry, and is the amount of energy dissipated per bit [9]. Recent B. Selection of Cluster Head researches in wireless sensor networks have focussed Clustering leads to load balancing and minimized on improving the energy consumption by analyzing need of network maintenance. Selection of optimum various parameters and increasing the network cluster head is the main area of research these days. lifetime. Various algorithms have been developed. Low Energy Adaptive Clustering Hierarchy (LEACH) is one of the II. RELATED WORK very first protocol and all the further protocols are The limited battery power source is the biggest based on this. The selection of cluster head is challenge for the wireless sensor networks as it probability based and it leads to load balancing but directly influences the lifetime of networks. For randomly selected cluster heads are not optimum in covering larger area and monitoring of areas for a number so imbalanced energy consumption will be longer time, it is required that the sensor nodes remain there [13]. Residual energy of a sensor node also alive for a longer period otherwise network cannot affects the lifetime of a network so it can be one of the operate in an efficient manner. Thus it has become parameter to choose the best cluster head so as to important to use such methodologies in order to increase time for which network operates . the residual increase this lifetime of networks such that services energy has been considered as a parameter for cluster are provided but with reduced energy consumption. head selection in [14]. The residual energy of a sensor Recent works are aimed at energy efficiency and node is given by: improvement mechanisms adopted during node = -[( )+( )] (5) deployment, selection of cluster head and data where , are the energies required by the node aggregation. for transmission and reception of the packet respectively[14]. In [15], Adaptive Cluster Habit A. Node Deployment (ACH) protocol selects the optimum number of cluster Effective node deployment leads to increased heads, and this proposed protocol is 31.8%, 35.6%, coverage area, better connectivity, and energy saving 22.5% and 10.7% more efficient than Low Energy in the network. Nodes deployed on the basis of Adaptive Clustering Hierarchy (LEACH), Threshold heterogeneity in energy dissipation, improved the sensitive Energy Efficient Network (TEEN), Stable number of alive nodes by 80% in the network and lead Election Protocol (SEP), Distributed Energy Efficient to extended network lifetime [10]. The average energy Clustering (DEEC) in terms of network lifetime. dissipation in combinations of sensor nodes made is Energy consumption is more in processing the packets calculated on the basis of equation given by: of information, one such factor is considered in [16] which is length of the packet. The energy consumed (l,d)= l + : d< by the Cluster head is given by: =l + :d =L*( + )+L* * (6) > (4) where L is length of the packet, is the energy being dissipated to run the transmitter or receiver ISSN: 2231-5381 http://www.ijettjournal.org Page 181 International Journal of Engineering Trends and Technology (IJETT) – Volume 33 Number 4- March 2016 circuitry, is the amount of energy dissipated per bit, is the energy required in data aggregation by the Cluster Head (CH) [16]. An intelligent routing protocol [17], used reinforcement learning algorithm for the selection of cluster heads in a network and considered parameters like battery level of the node and distance between a node and the base station. The main focus of the work is on the three output parameters network lifetime, packet delay and packet delivery. The network lifetime increases up to 20.5%, packet delivery factor increases by 47% and packet delay is minimized. Another approach for energy efficient clustering is proposed in [18] using fuzzy logic. The parameters considered for selection are residual energy of nodes and distance of nodes from base station. This approach increases the network lifetime up to 5-7% as compared to LEACH. C. Data Aggregation For the purpose of increased energy efficiency and increased network lifetime, data transmission is also minimized in some approaches by data aggregation. A new data collection approach Maximum Amount Shortest Path is used in [19], it considers shortest path, residual energy and delay for improvement of the network lifetime. It is an improvement of ant colony optimization. In [20], time constraint during the data aggregation at sensor nodes is considered and provided optimal time allotment for intermediate node. The energy consumption and other output parameters considered for the performance evaluation of the proposed methods in various recent works has been shown in Table I. The improvements with the proposed methods have been evaluated considering the performance metrics with increasing node density or other factors. III. CONCLUSION The limited source of battery power has become major constraint for the operation of the wireless sensor networks. Various protocols and schemes proposed in recent times have led to improvements in the lifetime of the networks. Different protocols have considered different input parameters and performance metrics like network lifetime, throughput, node density, quality of service and others have been used to show the improvement as compared to previous works. So we conclude that parameters like energy of the node, distance from the base station, length of the packet etc. can affect the network lifetime and performance ISSN: 2231-5381 of the wireless sensor networks and these parameters can be further analysed to make more changes in the performances. Table I: Output parameters and performance evaluation of various methods for energy efficiency PROPOSED METHOD OUTPUT PARAMETERS PERFORMANCE EVALUATION Optimum node deployment [10] Energy Dissipation 0.0022J Network lifetime Improved Barrier coverage algorithm[11] Cluster head selection Based on residual energy & cluster reformation [14] Adaptive Cluster Head (ACH)[15] Energy consumption Increased up to 30% 33.62J less consumption Network lifetime 34.63% Improvement Average Energy consumed Decreased from 13.76J to 11.87J with increase in nodes Increased from 280 sec. to 670 sec. Network lifetime Network Lifetime Throughput Improved by 39.4% Increased by 30.7% Stability period Increased by 40% Packet Energy Consumption Length Optimization Using Delta Modulator [16] Cluster head Network lifetime Selection using reinforcement Packet delivery learning[17] 30% energy saved with optimization Cluster head selection using Fuzzy logic [18] 16% Increased http://www.ijettjournal.org No. of alive nodes 16% increased 44% increased Page 182 less International Journal of Engineering Trends and Technology (IJETT) – Volume 33 Number 4- March 2016 REFERENCES [1] C. Li, M. Ye, Guihai Chen, J. Wu, “An Energy Efficient Unequal Clustering Mechanism for Wireless Sensor Networks”, IEEE International Conference on Mobile Adhoc and Sensor Systems”, pp. 604-612, 2005 [2] A.Alfieri, A.Bianco, P.Brandimarte, “Maximizing System Lifetime in Wireless Sensor Networks”, pp 390-402, 2007 [3] M. Leghari, S. Abbasi, Dr. L. 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