Neetesh Purohit

Fuzzy logic based clustering in wireless sensor networks: a survey

Wireless sensor networks (WSNs) have limited resources, thus extending the lifetime has always been an issue of great interest. Recent developments in WSNs have led to various new fuzzy systems, specifically designed for WSNs where energy awareness is an essential consideration. In several applications, the clustered WSN are known to perform better than flat WSN, if the energy consumption in clustering operation itself could be minimised. Routing in clustered WSN is very efficient, especially when the challenge of finding the optimum number of intermediate cluster heads can be resolved. Fortunately, several fuzzy logic based solutions have been proposed for these jobs. Both single- and two-level fuzzy logic approaches are being used for cluster head election in which several distinguished features of WSN have been considered in making a decision. This article surveys the recent fuzzy applications for cluster head selection in WSNs and presents a comparative study for the various approaches pursued.

A Moving Base Station Strategy Using Fuzzy Logic for Lifetime Enhancement in Wireless Sensor Network

Lifetime enhancement has always been of crucial importance for wireless sensor network due to resource limitations of sensor nodes. In the recent past some researchers have suggested moving base station method to enhance the lifetime of wireless sensor network. However the movement of base station in sensor field is a complex problem and practically may not be feasible. In this paper, we propose a unique movement strategy for base station to reduce energy consumption. The motion of base station is governed by fuzzy logic inference mechanism. The strategy used in this paper is unique in the sense that the base station is allowed to move only on a predefined path making it practically more feasible. Final results are compared with the method having stationary base station and method in which motion of base station is governed by fuzzy logic inference mechanism but without following any predefined path. Simulation results show that our strategy enhances lifetime by a significant amount as compared to stationary base station. We further propose that by increasing or decreasing area covered by predefined path we can get desired lifetime intermediate between the above two approaches.

An Energy Efficient Approach for Clustering in WSN using Fuzzy Logic

Lifetime augmentation has always been an interesting subject of vital significance in wireless sensor networks. Excess extent of energy is dissipated during data transmission to the base station (sink) from normal sensor nodes. Clustering is an efficacious way of augmenting the life span by optimizing (reducing) the energy dissipation of WSNs. Many numbers of researchers have employed fuzzy logic based solution for election of cluster- head in the earlier past. In our proposed scheme two strong parameters; energy and centrality have been considered for cluster head decision. In this work we assumed both the parameters simultaneously to elect cluster head which makes this approach energy efficient and more feasible. Simulation results are contrasted with the former approaches of cluster-head election. Simulation results exhibits that the proposed scheme minimizes energy consumption and thereby enhances life span of wireless sensor network by a significant amount.

Reliability analysis of Wireless Sensor Network

Wireless sensor network (WSN) is a distributed system which possesses time varying wireless connectivity without any infrastructural backbone. Scarce energy and computation power of individual nodes, unattended and harsh operation environment, self configuration after random deployment etc complexities are known characteristic features of a WSN. Despite aforesaid constraints WSN has been evolved as a tool to bridge the gap between physical world of sensors/actuators and the virtual world of information and services. In some typical scenarios of many potential fieldspsila e.g. environmental monitoring, space explorations, military, agricultural, medical etc to name a few, WSN has been emerged as a promising technology. Sensing the environment and sending the sensed information to a remote place via sink are two primary jobs of a sensor network. These jobs are required to be done with greater reliability because some major decisions depend on the information received from WSN. The issue of quantifying reliability for a WSN is addressed in this paper.

An optimised fuzzy clustering for wireless sensor networks

Minimising energy consumption has always been an issue of crucial importance in sensor networks. Most of the energy is consumed in data transmission from sensor nodes to the base station due to the long distance of nodes from the base station. In the recent past, a number of researchers have proposed that clustering is an efficient way of reducing the energy consumption during data transmission and enhancing the lifetime of wireless sensor networks. Many algorithms have been already proposed for cluster head selection. In this work, we analyse and compare the lifetime of the network with three different fuzzy-based approaches of cluster head selection. The three strong parameters which play an important role in lifetime enhancement – energy, centrality and node density – are considered for cluster head selection in our proposed fuzzy approaches. In the first approach, energy and centrality are considered simultaneously in a fuzzy system to select the cluster heads. In the second approach, energy and node density have been taken in a fuzzy system to select the cluster heads. In the third approach, node density and centrality are considered simultaneously by a fuzzy system to select the cluster heads. Simulation results of these fuzzy logic-based approaches show that all the three approaches are superior to the Low-Energy Adaptive Clustering Hierarchy (LEACH). Simulation results also show that the energy-centrality-based fuzzy clustering scheme gives best performance among all the three fuzzy-based algorithms and it enhances the lifetime of wireless sensor networks by a significant amount.

Minimization of Energy Consumption of Wireless Sensor Networks Using Fuzzy Logic

Extending the lifetime of the wireless sensor networks has always been a crucial challenge for the researchers. Most of the energy is consumed in data transmission to the sink. In the recent past some researchers have suggested mobile sink method to minimize energy consumption in wireless sensor networks. The movement of sink is governed by fuzzy logic based mechanism. In this work base station is allowed to move only on a predefined circular path making it practically more feasible. Simulation results are compared with the method having stationary base station. Simulation results show that our scheme reduces energy consumption and thereby enhances lifetime of wireless sensor network by a significant amount as compared to stationary base station case.

Analysis of lifetime of wireless sensor network with base station moving on different paths

Energy saving is the top most requirement of the wireless sensor network (WSN) for making it a cost effective technology. In this direction, minimisation of the distance between the communicating nodes should be an obvious choice, as it consumes the biggest chunk of the node energy. But the stationary nature of nodes (including the base station) in the standard WSN does not allow it; thus, the provision of a moving base station has been recently introduced. A few schemes with moving base station have already been developed but they suffer from several drawbacks, for example, the path over which the base station can move has not been considered which is highly unfeasible. An efficient and implementable moving strategy is needed to be developed, which is the primary goal of the present work. The fuzzy logic inference mechanism has been developed and the performance of the same is illustrated in terms of WSN lifetime. Lifetime of a WSN depends on many factors, for example, residual energy of nodes, distance between communicating nodes and base station, etc. Ability of fuzzy logic theory to address more than one factor simultaneously gives it an upper edge over other alternatives. The present work explores the possibilities of building either a circular shaped or a cross-shaped path in the deployment area. A relative study of the movement of base station on these paths has been presented. Simulation results show that the cross path always give better performance than circular path and the lifetime improves with increase in the length of the predefined path.

Design of wide band circularly polarized textile antenna for ISM bands at 2.4 and 5.8 GHz

This paper describes the design and fabrication of circularly polarized wideband textile antenna resonating at 2.4 GHz and 5.8 GHz ISM bands. The textile antenna that is designed for wireless body centric communications should be low profile, light weight, comfortable against skin and unobtrusive to be worn so that it can be easily accepted by the general public. With the advent and easy availability of electrotextile materials it is now possible to fabricate textile antennas that are very suitable to be used for portable applications. Here, conductive metalized nylon fabric (Zell) is used as a conducting material. For increasing the flexibility and comfortability to the user, denim is used as a substrate material. The proposed antenna is optimized on software package CST microwave studio 2011 for larger bandwidth. It has been found that this circularly polarized antenna has very high 3-dB axial ratio bandwidth and -10 dB impedance bandwidth in free space with very high gain in both ISM bands. The antenna prototype is finally checked on the human body and free space with VNA. The obtained results have validated the design idea.

A New Scheme for Cooperative Communication in LEACH Based Wireless Sensor Network

Wireless Sensor Networks need energy efficient protocol for carrying out various operations. Cooperation among nodes may save significant energy by avoiding retransmission from distant nodes. In this work, a new scheme has been suggested for LEACH based WSN by introducing cooperation among various cluster heads. Significant improvement in BER has been observed for comparable overall lifetime of ordinary WSN. Cooperative communication with punctured convolutional channel coding is used in operation phase where as point to point transmission technique is used in clustering phase. Rayleigh fading channel and additional energy consumption due to retransmissions by relay nodes has been accounted in simulation. Bit error rate (BER) and overall life time of WSN is found to be dependent on the number of cooperative nodes, sensor nodes density in WSN, etc factors.

Performance analysis of wireless sensor network with virtual MIMO

In this work, ray based simulation approach has been used for estimating the performance of WSN with MIMO and SISO techniques. The ray based simulation should produce more accurate results than model based simulation approach because it is more close to real life environment. In addition to simulation, Markov model based analytical approach has also been adopted. The transition probabilities among various states of the Markov model has been evaluated using the data produced by the ray trace simulator. It is also giving better performance as compared to Rayleigh fading channel based Markov models approach. LEACH clustering protocol has been used with a slight modification in terms of selecting secondary cluster head. Alamouti space-time code has been used with V-MIMO and significant improvement in the overall life time has been observed as compared to SISO WSN.