Tamoghna Ojha

Wireless sensor networks for agriculture

The existing state-of-the-art in wireless sensor networks for agricultural applications is reviewed thoroughly.The existing WSNs are analyzed with respect to communication and networking technologies, standards, and hardware.The prospects and problems of the existing framework are discussed with case studies for global and Indian scenarios.Few futuristic applications are presented highlighting the factors for improvements for the existing scenarios. The advent of Wireless Sensor Networks (WSNs) spurred a new direction of research in agricultural and farming domain. In recent times, WSNs are widely applied in various agricultural applications. In this paper, we review the potential WSN applications, and the specific issues and challenges associated with deploying WSNs for improved farming. To focus on the specific requirements, the devices, sensors and communication techniques associated with WSNs in agricultural applications are analyzed comprehensively. We present various case studies to thoroughly explore the existing solutions proposed in the literature in various categories according to their design and implementation related parameters. In this regard, the WSN deployments for various farming applications in the Indian as well as global scenario are surveyed. We highlight the prospects and problems of these solutions, while identifying the factors for improvement and future directions of work using the new age technologies.

Game-Theoretic Topology Controlfor Opportunistic Localizationin Sparse Underwater Sensor Networks

In this paper, we propose a localization scheme named Opportunistic Localization by Topology Control (OLTC), specifically for sparse Underwater Sensor Networks (UWSNs). In a UWSN, an unlocalized sensor node finds its location by utilizing the spatio-temporal relation with the reference nodes. Generally, UWSNs are sparsely deployed because of the high implementation cost, and unfortunately, the network topology experiences partitioning due to the effect of passive node mobility. Consequently, most of the underwater sensor nodes lack the required number of reference nodes for localization in underwater environments. The existing literature is deficient in addressing the problem of node localization in the above mentioned scenario. Antagonistically, however, we promote that even in such sparse UWSN context, it is possible to localize the nodes by exploiting their available opportunities. We formulate a game-theoretic model based on the Single-Leader-Multi-Follower Stackelberg game for topology control of the unlocalized and localized nodes. We also prove that both the players choose strategies to reach a socially optimal Stackelberg-Nash-Cournot Equilibrium. NS-3 based simulation results indicate that the localization coverage of the network increases upto 1.5 times compared to the existing state-of-the-art. The energy-efficiency of OLTC has also been established.

MobiL: A 3-dimensional localization scheme for Mobile Underwater Sensor Networks

In this paper, we introduce a 3-dimensional, distributed, iterative, and ‘silent’ localization protocol for Mobile Underwater Sensor Networks (MUSNs) named as Mobility Assisted Localization Scheme (MobiL). The existing solutions addressing the localization problem in underwater sensor networks (UWSNs) either consider the sensor nodes to be stationary or require powerful nodes, which can directly communicate with the surface sinks. Such assumptions are not applicable in MUSNs, where sensor nodes are affected by passive node mobility and the acoustic communication channel is severely impaired by high propagation loss. On the other hand, MobiL requires only three anchor nodes capable of providing the initial location beacon and all other nodes are ordinary sensor nodes. We exploit the spatially correlated mobility pattern of UWSNs and apply it to localize the sensor nodes. Also, we employ the ‘silent’ listening of beacon messages, which empowers MobiL to be energy-efficient. Simulations in NS-3 show that the proposed scheme successfully localizes nearly 90% of the total sensor nodes with localization error in the order of 25–30% of the error threshold in highly mobile UWSNs.

ENTICE: Agent-based energy trading with incomplete information in the smart grid

Abstract In this paper, energy trading for the distributed smart grid architecture is projected as an incomplete information game —a viewpoint that contrasts from all the existing pieces of literature available on the broader issue of energy management in smart grid. The incomplete information is considered as the real-time demand and price to grid and customers, respectively, due to the packet loss in the communication network. Therefore, the paper addresses a realistic scenario, in which real-time information to the destination may not be guaranteed to be received adequately, due to the packet loss. In the proposed scheme, we introduce two types of intelligent agents— customer-agents and grid-agent . The customer-agents are deployed at the customers׳ end, and are capable of estimating adequately the real-time price decided by the grid. On the contrary, the grid-agent is deployed at the service provider׳s end, and are also capable of estimating adequate real-time energy demand from the customers. Therefore, one of the key advantage of the proposed agent-based scheme is that the customers and the grid are not involved in complex calculations in order to take real-time decisions for cost-effective energy management, while there is information loss in the communication networks. In the proposed game model, the grid-agent and the customers agents are the players, and estimate real-time demand and price based on the probability of belief to each other. We show the existence of Bayesian Nash Equilibrium in the proposed model, where the utility of the players is maximized. We compare the real-time price with and without packet loss as the price with incomplete and complete information, respectively. We observe that the proposed model is beneficial for the grid, as its utility is maximized. The simulation results show that the utility of the grid increases approximately 40% over that of the existing ones under the scenario of information incompleteness.

Dynamic Duty Scheduling for Green Sensor-Cloud Applications

In this paper, we propose a dynamic duty scheduling scheme for minimizing the energy consumption of the on-field sensor networks in a sensor-cloud application framework. The conjugation of cloud framework with Wireless Sensor Networks (WSNs) adds enhanced processing and storage capacity to the on-field WSN applications. However, the WSN applications performing periodic information update to the cloud exhibit low network lifetime, low resource utilization, and high cost. In this regard, the advent of the sensor-cloud technology facilitates dynamic duty scheduling of the on-field WSNs. As a result, the on-field WSNs attain improved energy-efficiency and cost-effectiveness. The simulation results show the effectiveness of the proposed scheme over the traditional scenarios.

HASL: High-Speed AUV-Based Silent Localization for Underwater Sensor Networks

The existing solutions that have been proposed to address the localization problem for mobile Underwater Sensor Networks (UWSNs) exhibit performance challenges such as high message overhead, localization error, and cost. Few Autonomous Underwater Vehicle (AUV) based methods were introduced to utilize the flexibility of movement of an AUV. In this paper, we propose a distributed, 3-dimensional, energy-efficient localization scheme, named High-Speed AUV-Based Silent Localization (HASL), for large-scale mobile UWSNs. Three AUVs are used to provide beacon messages to localize the mobile sensor nodes ‘silently’. Therefore, with the use of high-speed AUV and ‘silent’ listening, we design an efficient scheme capable of addressing some of the above mentioned challenges with the existing solutions. We evaluated our proposed scheme in NS-3 simulator. Simulation results show that HASL achieves more than 90% localization coverage with localization error in the order of 2-7 meters.

Sensing-cloud

We present the physical node virtualization model for agricultural applications.We justify the advantages of sensor-cloud framework over traditional WSN-based framework.We formulate the sensor node utilization model targeting agricultural applications.We present a model for providing cost effective agro-computing services to large number of farmers.The proposed model is suitable for setups with multiple organizations, users, and applications. The advent of the sensor-cloud framework empowers the traditional wireless sensor networks (WSNs) in terms of dynamic operation, management, storage, and security. In recent times, the sensor-cloud framework is applied to various real-world applications. In this paper, we highlight the benefits of using sensor-cloud framework for the efficient addressing of various agricultural problems. We address the specific challenges associated with designing a sensor-cloud system for agricultural applications. We also mathematically characterize the virtualization technique underlying the proposed sensor-cloud framework by considering the specific challenges. Furthermore, the energy optimization framework and duty scheduling to conserve energy in the sensor-cloud framework is presented. The existing works on sensor-cloud computing for agriculture does not specifically define the specific components associated with it. We categorize the distinct features of the proposed model and evaluated its applicability using various metrics. Simulation-based results show the justification for choosing the framework for agricultural applications.

Oceanic forces and their impact on the performance of mobile underwater acoustic sensor networks

SUMMARY This paper focuses on the performance analysis of Underwater Wireless Acoustic Sensor Networks (UWASNs) with passively mobile sensor nodes moving because of the influence of major oceanic forces. In an UWASN, passive node mobility is inevitable. Therefore, the performance analysis of UWASNs renders meaningful insights with the inclusion of a mobility model, which represents realistic oceanic scenarios. In this regard, the existing works on performance analysis of UWASNs lack the consideration of major dominating forces, which offer impetus for a nodes mobility. Additionally, the existing works are limited to only shallow depths and coastal areas. Therefore, in this paper, we have proposed a physical mobility model, named Oceanic Forces Mobility Model, by incorporating important realistic oceanic forces imparted on nodes. The proposed model considers the effects of node mobility in 3-D space of water. We also present an analysis on the impact of node mobility on the performance of UWASNs in terms of network dispersion and localization. Simulation results indicate performance degradation of UWASNs in the presence of oceanic forces—localization coverage decreases by 36.70%, localization error increases nearly by 21.14%, and average energy consumption increases by 3% approximately. Copyright

Performance analysis of distributed underwater wireless acoustic sensor networks systems in the presence of internal solitons.

SUMMARY In this paper, we have analyzed the performance of distributed Underwater Wireless Acoustic Sensor Networks (UWASNs) in the presence of internal solitons in the ocean. Internal waves commonly occur in a layered oceanic environment having differential medium density. So, in a layered shallow oceanic region, the inclusion of the effect of internal solitons on the performance of the network is important. Based on various observations, it is proved that nonlinear internal waves, that is, solitons are one of the major scatterers of underwater sound. If sensor nodes are deployed in such type of environment, internode communication is affected because of the interaction of wireless acoustic signal with these solitons, as a result of which network performance is greatly affected. We have evaluated the performance of UWASNs in the 3-D deployment scenario of nodes, in which source nodes are deployed in the ocean floor. In this paper, four performance metrics, namely, Signal-to-interference-plus-noise-ratio (SINR), bit error rate (BER), Delay (DELAY), and energy consumption are introduced to assess the performance of UWASNs. Simulation studies show that in the presence of internal solitons, SINR decreases by approximately 10%, BER increases by 17%, delay increases by 0.24%, and energy consumption per node increases by 53.05%, approximately. Copyright

Effects of Wind-Induced Near-Surface Bubble Plumes on the Performance of Underwater Wireless Acoustic Sensor Networks

This paper analyzes the effects of near-surface oceanic bubble plumes on the overall performance of underwater wireless acoustic sensor networks (UWASNs). The existence of bubble plumes in surface and subsurface ocean water columns is inevitable in most windy oceanic environments. There exists studies reporting the anomalous behavior of acoustic signal propagating through oceanic bubble plumes due to absorption and scattering. However, most of the existing network protocols designed for use in UWASNs are ignorant of these effects. In this paper, we first mathematically model the absorption effects of these bubble plumes on the acoustic communication media. Consequently, the overall performance of UWASNs is studied with respect to different parameters. Simulation-based results show that in the presence of bubble plumes, packet delivery ratio decreases by 34% while average energy consumption per node increases by 7%. In addition, signal-to-interference-plus-noise ratio decreases by