1. INTRODUCTION
Wireless Sensor Networks (WSN) consists of large number of sensor nodes distributed across a geographical area in highly dense manner. These nodes are of low cost and use less energy to perform various functions. These sensors have the ability to communicate with each other and route the data to next node or back to the Base Station (BS). Sensor nodes in a sensor network communicate with other nodes and collect the information.
1.1 ARCHITECTURE OF WSN
Sensor node is made up of four basic components: a sensing unit, a processing unit, a transmission unit and a power unit. Sensing unit collects information using sensor and analog to digital converters (ADC). ADC converts the analog signals produced by the sensor to the
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iii) Dynamic network topologies
Sensor nodes are deployed without any prior planning so the topology of network may change due to many reasons like change in node position, failure of node due to physical damage, and limited available power. iv) Adaptability
Movements of nodes cause the communication failure and the re-construction of route should be fast and adaptable.
v) Data aggregation
Data aggregation reduces the amount of energy during transmission of data between nodes, hence increasing the lifetime of node. vi) Quality of Service
WSNs have been used for various different applications. Some applications such as military fields are very critical and needs the reliable service timely. vii) Security
A secure communication between nodes is very important. There should be data confidentiality and integrity.
2.2 LOW ENERGY AWARE CLUSTER HIERARCHY (LEACH)
Low Energy Aware Cluster Hierarchy (LEACH) is one of the hierarchical routing protocols that uses very limited amount of energy and increases the lifetime of the network. Transfer of Data through Wireless Sensor Network is a challenging task today particularly with the existence of Denial of Service (DoS) attacks, Flooding attack, Black hole attach and Gray hole attack. All attacks mentioned above are implemented and their impacts on the performance of the LEACH in terms of different metrics including packet
A group of wireless sensor nodes (devices) dynamically constructs a temporary network without the exercise of any pre-existing network infrastructure or centralized administration. The main goal of ad-hoc networking is multihop broadcasting in which packets are transferred from source node to destination node through the intermediate nodes (hops). The main function of multi hop WSN is to enable communication between two terminal devices through a bit of middle nodes, which are transferring information from one level to another level. On the foundation of network connectivity, it dynamically gets to determine that which nodes should get included in routing, each node involved in routing transmit the data to further
A WSN is a type of wireless networks that consists of collection sensor nodes which are tiny devices. Each sensor node of the network has different processing capability. It may contain multiple types of memory (program, data and flash memories), have a RF transceiver, have a power source (e.g., batteries and solar cells), and accommodate various sensors and actuators. The nodes communicate wirelessly and often self-organize after being deployed in an ad hoc fashion [13, 14]. Optimum need of each sensor node is to maximize its own utility function. Also the whole network requires resource assignments balance to perform in a useful and efficient way. This chapter presents a brief survey on WSNs showing its types, characterizing features, protocols and applications.
A Wireless Sensor Network is one kind of wireless network includes a large number of circulating, self-directed, minute, low powered devices named sensor nodes called motes. These networks certainly cover a huge number of spatially distributed, little, battery-operated, embedded devices that are networked to caringly collect, process, and transfer data to the operators, and it has controlled the capabilities of computing & processing. Nodes are the tiny computers, which work jointly to form the networks. The sensor node is a multi-functional, energy efficient wireless device. The applications of motes in industrial are widespread. A collection of sensor nodes collects the data from the surroundings to achieve specific
World Wide Web). The nodes can be static or dynamic [24]. Wireless Sensor Networks (WSN) will continue to play a very important role in our day to day lives. A WSN contains of sensor nodes that are powered by little unique batteries. These sensor nodes are densely arranged in the area to be monitored to sense and transmit information towards the base station. WSN can simplify structure design and operation, as the environment being monitored does not need the communication or energy infrastructure connected with wired networks [25].
each node maintains its own schedule table where its neighbor nodes schedule are stored. First node listens for a particular time , if it is not hearing from another node it randomnly goes to sleep with broadcasting a SYNC message .
Abstract - Wireless Sensor Networks (WSN) comprises of several tiny, low-cost, resource constrained sensor nodes. These nodes are placed in harsh environments and generally are used for air pollution monitoring, water quality monitoring, industrial monitoring, health monitoring and more. Routing is difficult in such surroundings primarily due to the unique constraints the wireless sensor networks suffer from. Wireless sensor network is highly dynamic, making existing routing protocols ineffective. This paper concentrates on energy efficiency of the protocols. Both the protocol presented are hierarchical and cluster based. Both have sensor nodes and a base station (BS). The BS selects the Cluster Heads (CH) among themselves. CH is the elected sensor node which passes on the sensor data collected by sensor nodes of its cluster to either BS or other CH. All candidate nodes for becoming CH are listed, based on the various factors like relative distance of the candidate node from the Base Station, outstanding energy level, possible number of neighboring sensor nodes the
Wireless sensor networks are often referred to as self-adaptable or self-organizing and self-mending or self-healing networks. The self-organizing property of the network facilitates for a node to join the network without any intervention automatically. The nodes in a network can reconstruct their link organizations and can form an alternative paths whenever a node in that link fails or gets damaged. The implementation of these two properties are very precise to the network topology and the network characteristics like scalability, cost, performance and various other issues are decided by the implementation capability of the properties. The sensor nodes in the wireless sensor networks does not require any engineering and are easily deployable. The sensor nodes often with multi hop connections are responsible for
Although wireless sensor network and the other types of network sometimes need same security requirements, providing security service for WSN own more challenges
Hence, WSN technology has very broad application prospects, which can be used in military, industrial and agricultural control, urban management, biomedical, environmental testing, disaster relief and other fields. However, in many of these applications, the environment could be hostile and manual placement of sensor nodes might not be possible. In these situations, the nodes are expected to be deployed randomly or be sprinkled from airplanes and will remain unattended for weeks or months without any battery replenishment [4]. Therefore, energy conservation is a key issue in the design of systems based on WSNs. Due to the limited energy resource in each sensor node, we need to utilize the WSN in an
The centralized approach is to recognize the most frequently used approach and to diagnose abnormal data readouts caused by a monitoring process, malfunctions of the components of the sensor node, or environmental events. In the centralized failure detection, each sensor node periodically collects its read and sends a packet on the radio to the central base node responsible for identifying faulty sensor nodes in WSN. In this concern, there are many research activities were reported. Gupta and Younis tried to provide a tolerant grouping mechanism to fail to provide the sensor by performing a sensor recovery in the runes in which the bridge has recovered. The mechanism is separated into two phases: 1) detection
Wireless Sensor Networks (WSN) consists of a collection of nodes which are deployed randomly in a hostile environment. It has a fixed infrastructure and self-organized in to an arbitrary topology. Though there are advancements in technology, security in WSN is a principal concern. As the deployed sensors are in an open environment, the intrusion of attacks is very much higher. Also the WSN has broadcast nature of communication; they are easily affected by the attacks. Commonly prevailing attacks are Denial of Service (DoS) attacks, spoofing attack, selective forwarding attack, sinkhole attack, sybil attack, wormhole attack, black hole attack, grayhole attack, HELLO flood attack, etc. However we observe that Denial of Service attack is a
In the previous section, we mainly focus on the connectivity and related survivability issues of WSNs. It is the foundation that we deploy WSNs to achieve its main objective which is to monitor the field of interest / detect desired data and it is coverage that determines whether the field of interest is under strict surveillance or not. So, in this section, we will summarize the related work on integrated connectivity and coverage problem in WSN. In [68], [69], it’s clear that connectivity only requires that the location of any active node be within the communication range of one or more active nodes such that all active nodes can form a connected communication backbone, while coverage requires all locations in the coverage region be
Besides the connectivity, the concept of coverage is another fundamental need to be understood for designing a WSN based system. The coverage is always considered as a measurable metric to evaluate the level of the monitoring for a specific FoI. Based on specified requirements of different applications, the
Therefore, there is a need to find a suitable algorithm which clusters sensor nodes in such a way that when a BS fails and a new BS takes the charge, new group key gets established with minimum computation and less energy consumption.
Wireless Sensor Networks refers to incredibly distributed networks of small and lightweight wireless nodes with very confined capabilities, deployed in large numbers in an open environment to monitor the environmental conditions by measuring physical parameters such as temperature, pressure, humidity etc. Each and every node (sensor) has a microprocessor and a small amount of memory for sensing, signal processing and for communication purposes. Each sensor node communicates wirelessly with different regional nodes within its radio conversation range. Deployment of WSN’s evade installation costs however at the same time power efficiency as a main challenge. A scheme of a wireless sensor node connected to the internet is shown in Fig. 1: wireless sensor networks ordinarily contains sensing unit, processing unit, transmission unit and power unit.