Amulya Ratna Swain

A standard Wireless Sensor Networks(WSNs) comprises of low-cost sensor nodes embedded with small batteries. To enhance the network lifetime of WSN, the number of active nodes among the deployed nodes should be minimum. Along with this, it must be ensured that coverage of the targeted area would not get affected by the currently active nodes. Considering different applications of WSN, there is still a demand for full coverage or partial coverage of the deployed area. Irrespective of the circumstances, a proper sleep scheduling algorithm needs to be followed. Else, the active nodes will be tuckered out of the battery. Random distribution of the sensor nodes in a common area may have multiple active nodes. It is essential to identify the redundant number of active nodes and put them into sleep to conserve energy. This paper has proposed a methodology where the active sensor nodes form a hierarchical structure that heals itself by following a level-wise approach. In the meantime, it also detects the total number of redundant nodes in the coverage area. The performance of the proposed protocol is evaluated using the Castalia simulator. The simulation results show that the proposed level-wise periodic tree construction approach increases the network's durability in conjunction with the level wise approach.

The wireless sensor network(WSN) has been extensively used to monitor and control the natural ecosystem on a large scale like air quality, natural life, etc. Low battery power,low storage, and limited processing ability are the most critical areas of concern in WSN. To reduce energy utilization, the sensor nodes in WSN work in a cyclic process between active and sleep mode. A certain number of nodes are chosen active and they areresponsible for sensing as well as data transmission and rest of the nodes are gone to sleep. In order to lengthen the lifetime of network, in this paper we proposed a level wise periodic tree construction algorithm that uses a specific set of nodes to participate in tree construction, instead of all the nodes, to minimize the energy consumption. In this proposed approach, the main idea is to put the nodes, which are currently active and have already spent a significant amount of energy, to sleep mode, while giving chances to the leaf nodes, which has comparatively spent less energy, to become an active node and maintain connectivity. The performance of the proposed protocol is evaluated usingthe Castalia simulator. The simulation results show that the proposed level-wise periodic tree construction approach increases the durability of the network in conjunction with the non-level approach.

A wireless sensor network is a collection of batterypowered sensor nodes distributed in a geographical area. Inmany applications, such networks are left unattended for along period of time. These networks suffer from the problemslike high energy consumption, high latency time, and end- to-end low packet delivery ratio. To design a protocol that findsa trade-off between these problems is a challenging task. Inorder to mitigate energy consumption issue, different existingMedia Access Control (MAC) protocols such as S-MAC, RMAC,HEMAC, and Congestion-less Single Token MAC protocols havebeen proposed which ensure better packet delivery but fail toensure energy efficiency due to high end-to-end latency. Theproblem of high end-to-end latency is resolved with the existingrouting protocols such as Fault Tolerant Multilevel Routingprotocol (FMS)and Enhanced Tree Routing (ETR) protocol.AS2-MAC and Multi Token based MAC protocol are able toimprove the end-to-end packet delivery ratio. However, thehierarchical network structure used in these protocols increasestime and energy consumption during network reconstruction.This problem was further resolved in Distributed HierarchicalStructure Routing protocol by constructing the network structurein a distributed manner. In all these existing protocols, efficienttoken management and reliable data delivery ratio was notproperly addressed, which in turn consume more energy. So,it is clear that MAC and routing protocols both together cangive better results related to data transmission in WSN. Inorder to achieve the same, in this paper, we propose a reliabledata transmission algorithm that satisfies both routing and MACprotocol to improve the end-to-end data delivery. The proposedprotocol uses different control message exchange that ensures datapacket delivery in each individual levels and it ultimately uses oftokens to ensure reliable data transmission along with reducedtraffic congestion during end-to-end data delivery. The algorithmconsiderably improves the packet delivery ratio along with reduceenergy consumption of each sensor node. Simulation studies ofthe proposed approach have been carried out and its performancehas been compared with the Multi Token based MAC protocol,AS-MAC protocol and ETR routing protocol. The experimentalresults based on simulation confirms that the proposed approachhas a higher data packet delivery ratio.

Wireless Sensor Network (WSN) mainly composed of a number of sensor nodes whose prime responsibility is to sense various events from the surrounding, do the processing on top of it and finally propagate the meaningful information to the observer through multiple intermediate nodes. Area coverage is one of the issues in WSN that guarantees the selected active nodes among all the deployed nodes should cover each point of the deployed area. The objective of complete area coverage is to find out redundant nodes and deactivate them, so that the remaining active nodes can cover the deployed area. Among the various existing approaches for area coverage in WSN, a grid-based approach has been proposed that provides a better way to select the active nodes or deactivate the redundant nodes from the grid rather than choosing the nodes from the deployed area. The existing approach goes with certain limitations such as how many numbers of grids need to be made in a certain deployed area with a certain number of nodes and how much percentage of nodes need to be selected from each grid. In order to avoid these limitations, in this paper, we propose a randomized grid-based approach that splits the intended area into small grids depending upon the density of nodes in a different location of the deployed area. At the same time, rather than selecting a certain percentage of nodes from each grid, here we select only one node from each grid and repeat the process till selected nodes satisfy the whole area coverage. Matlab simulator is used to study the simulation results of the proposed work, and it is found that the proposed randomized grid-based approach outperforms the existing grid-based approach both with respect to energy as well as throughput.

Wireless Sensor Networks(WSNs) consist of many self organized sensor nodes to monitor various activities like temperature, pressure, health condition, intrusion detection, etc. These sensor nodes mostly sense the events happening around them, process the sensed data, and send it to the base station using multiple hops. The base station is connected to the outside world who wants to access these sensed and processed data. In WSN, one of the most important challenge is to handle the collision during data transmission by multiple sensor nodes at the same point of time. The collision during data transmission is handled by proper MAC protocol. The MAC protocols for WSN are broadly categorized into 3 types, i.e. schedule, random, and hybrid. Among these 3 types of MAC protocols, the hybrid MAC protocols try to combine the advantage of both schedule and random based MAC protocols. In this paper, we proposed a distributed slot scheduling algorithm for hybrid MAC algorithm. This algorithm mainly focuses on preparing a schedule which bridges the gap between a feasible and an optimal schedule to handle the collision during the data transmission. In our proposed approach, first we find out two-hop neighbors of each node, then a particular slot is allotted to each node in order to prepare a feasible schedule using the RD-TDMA algorithm. Finally, the feasible schedule is fine tuned in a novel way to improve the efficiency in handling the collision by reducing the number of allotted slots. The proposed algorithm out performs the existing RD-TDMA algorithm in terms of number of slots required to handle the collision. The performance of the proposed protocol is carried out using Castalia simulator.

Wireless Sensor Networks(WSNs) consists of hundreds of nodes which are of low power, low cost, and tiny devices. The main functionality of these nodes is to sense the environment and send the sensed data to the observer. In order to validate and get the significance of sensing data, location information of the sensor node needs to be combined with the sensed data. In addition to this, there are many other issues of WSN such as routing, coverage, etc. which also need the location information of sensor nodes. Several approaches, including range-based and range-free, have been proposed to calculate positions for randomly deployed sensor nodes. In this paper, we proposed a distributed technique for localization of sensor nodes using few mobile anchor nodes. These mobile anchor nodes move in the network space and periodically broadcast beacon messages about their location. Static sensor nodes receive these messages as soon as they come under the communication range of any mobile anchor node and compute their position based on the range based technique. Another contribution of this paper is to identify the importance of mobile anchor node over static anchor node in localization. The performance of the proposed algorithm is carried out using the Castalia simulator. The simulation result shows that mobile anchor node provide better accuracy as compared to static anchor node for sensor node localization.

Wireless sensor network (WSN) has been widely implemented on a large scale that deals with monitoring and controlling the real environment. Coverage and connectivity are the two most active areas of concerned and also these functionalities are desired in WSN. Connectivity in WSN is generally defined as how well the nodes are connected so that the sink node must receive every bit of information sent by any other node. In the mean while, any event occurred at any point in the specified area should be detected, and it is referred as coverage in WSN. In order to fulfill both these requirements, in this paper, we proposed a coverage algorithm, in which a hierarchical structure is first constructed to satisfy the connectivity and the same structure is further extended to achieve full coverage in WSN. In this proposed approach, a tree is constructed by using a routing mechanism with sleep scheduling, such that all intermediate nodes which are participating in routing are in active mode, and the rest of the nodes are likely to be in sleep mode. Further, to fulfill the coverage requirement, we divide the leaf nodes again into two parts, i.e., The leaf nodes that are active, but not participating in routing, and the leaf nodes that are completely in sleep mode. The tree is reconstructed periodically to ensure balanced consumption of energy among all the nodes in WSN. The performance of the proposed protocol is carried out using the Castalia simulator.

A wireless sensor network (WSN) consists of a large number of sensor nodes distributed over a geographical area. A basic problem of WSNs is to reduce their energy consumption in order to enhance their life time. So, minimizing energy consumption becomes the most critical factor in the design of almost all WSN protocols. For end-to-end data transmission, media access control (MAC) and routing protocols play an important role in WSNs. Besides, these protocols mostly use the hierarchical structure for end-to-end reliable data delivery. The time and energy required to generate a hierarchical structure in a sequential manner is always high. So, in order to mitigate the above challenges, in this paper, we propose a distributed algorithm to generate the hierarchical structure where each node has two parent nodes except the root node. The intermediate nodes of the generated tree remain awake as they are selected as parent node based on their energy level, and other nodes are to be kept in the sleep mode in order to conserve energy. The distributed tree structure is periodically reconstructed considering the remaining energy of each node with a view to balance energy consumption of nodes in the whole WSN. The proposed approach also considerably reduces the average energy consumption rate of each node as we are able to put more number of nodes in the sleep mode in a distributed manner as compared to the existing approaches. Simulation studies of the proposed approach have been carried out using Castalia simulator and its performance has been compared with the existing sequential approach.