M Tech Dissertations

Permanent URI for this collectionhttp://drsr.daiict.ac.in/handle/123456789/3

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    Spectrum sensing in cognitive radio using quickest change detection framework
    (Dhirubhai Ambani Institute of Information and Communication Technology, 2015) Bharmal, Sara; Pillutla, Laxminarayana S.
    Spectrum sensing is a term associated with detection of primary (licensed) users (PU) by secondary (unlicensed) users (SU) to pursue opportunistic transmission of their data. The problem of spectrum sensing is challenging because of the distributed nature of SU. Since the presence or absence of PU has to be detected as quickly as possible therefore we use an approach based on quickest detection. To improve sensing efficiency we assume the SU to be equipped with multiple antennas for spectrum sensing. We also assume that each antenna makes fixed number of observations which are used to compute energy metrics. The energy metrics computed at various antennas are then combined using weights determined according to Fisher linear discriminant criterion. In our work we proposed a theoretical framework for change detection of the two hypotheses namely presence (or) absence of PU. From our simulation results we observe that the average detection delay decreases with an increase in the number of observations. The proposed weighted gain combining (WGC) gives lower average detection delay than the equal gain combining (EGC).
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    Precision agriculture using wireless sensor network
    (Dhirubhai Ambani Institute of Information and Communication Technology, 2015) Joshi, Nikita Rajeshbhai; Shrivastava, Sanjay
    Farming practices should evolve with the rapid increase in population. Recent growth in wireless sensor network (WSN) has the capability to meet this objective. Better quality in crop production can be achieved using real-time data collected through WSN. Also, greenhouse allows farming in a controlled environment. Hence, a combination of WSN and greenhouse gives better quality crop yield. Greenhouse requires climate control and fertigation management. Fertigation is a combination of irrigation and fertilization. Existing architectures for greenhouse management collect data of various parameters using sensor nodes and control values of parameters using actuators. These architectures have very limited capability to handle faults in sensors and actuators. Deployment of sensor nodes in these architectures is crop dependent. Therefore, while changing crops, modifications in the location of sensor node is needed and details of this modification should be entered manually in the database. Thus, they are not flexible architectures. In our work, a WSN based architecture for controlled environment like greenhouse is designed. This architecture provides for actuator control using crop requirements stored in the database. The architecture provides for deployment strategies for sensor nodes and actuators using the details about bed size, crop requirements etc. Localization algorithm is used to find the exact location of the sensor node. The architecture is flexible such that whenever location of sensors nodes needs to be changed, location of sensor nodes will be automatically detected using the localization algorithm. We have designed an algorithm to detect faults in sensor nodes and actuators. These faults are isolated or reported to the user. The architecture provides for network management strategies to control energy consumption of sensor nodes which eventually helps in increasing network lifetime. WSN algorithms for sleep scheduling and localization are used to support these features.We designed a system for a specific group of crops namely tomato, capsicum and cucumber using the architecture. This system is simulated in NS2 and it is verified that system is working as expected.
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    RF power harvesting and enhancing throughput in a optical link based sensor network
    (Dhirubhai Ambani Institute of Information and Communication Technology, 2013) Nambiar, Sainath Gopi; Ranjan, Prabhat
    Energy is one of the most important constraint inWireless Sensor Network (WSN), all the existing protocols, architectures revolve around the power plane. As the sensor network scale, their feasibility of implementation depends on its maintenance. The main aspect in maintenance of a WSN is the replacement of power sources. In the recent times, as implied applications of WSN grow, focus was more on running WSN on alternate sources of energy enabling longevity of sensor node. Here a system for harvesting radio frequency for an optical link based sensor network is developed using state of the art harvesting and storage technologies to be deployed inside a Tokamak. In multimedia based sensor network where optical link is used for communication, the data has to be encoded to enhance the data rate and increase the throughput. A multiple access scheme is developed over the existing infrared protocol for throughput enhancement with increased data rate using the Infrared Data Association (IrDA) protocol and hardware encoder.
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    Indoor target tracking using wireless sensor networks
    (Dhirubhai Ambani Institute of Information and Communication Technology, 2013) Keshvala, Sanjaykumar S.; Pillutla, Laxminarayana S.
    In this thesis, we consider indoor target tracking using wireless sensor networks (WSNs). In outdoor environment, target tracking can be done using Global Positioning Systems (GPS). But in the indoor environment this option lacks the desired accuracy. Therefore, we consider indoor target tracking using WSNs. We consider received signal strength indicator (RSSI) measurements for tracking owing to its simplicity due to lack of synchronization, that is required for other tracking metrics. Radio frequency identification (RFID) tags are mounted on different targets. The RFID tags emit beacons that are received by sensor nodes deployed in the tracking region of interest. The RSSI value obtained for every successful beacon frame received can be used for computing the position estimate of targets. The state of every target that comprises of its location in D-dimensions and the corresponding velocity in each dimension is assumed to evolve according to a first order Markov chain. Further, the state is assumed to evolve according to a linear model. The RSSI measurement associated with every target is a nonlinear function of the target state. Thus, we have a linear state evolution model and a non-linear measurement model. The targets state can be estimated using a bank of particle filters. To improve the accuracy of tracking algorithm the maximum likelihood estimates of the underlying radio environment is used. Thus, the mixed Bayesian-ML based tracking algorithm is robust to the time-varying nature of radio environment and thereby provides better tracking accuracy. We also considered a distributed implementation of the centralized tracking algorithm that is scalable for large scale WSNs. Simulation results demonstrate the efficacy of the proposed approach.
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    Power management of wireless sensor node by dynamic power measurement
    (Dhirubhai Ambani Institute of Information and Communication Technology, 2011) Kapasi, Jay; Ranjan, Prabhat
    Wireless sensor network(WSN) is a collection of spatially distributed autonomous sensor nodes, which cooperatively monitor physical or environmental conditions, such as temperature, sound, vibration, pressure, motion or pollutants. As Wireless sensor node cannot be connected to a large source of power supply, they have to run on portable energy sources such as solar cell and batteries. Thus it is very important to minimize the use of power in each individual node of network as even a single point of power failure may prove to be a great loss of functionality. Even though minimization of power consumption may appear to be a complex problem, due to advances in technology and availability of devices with different low power states, it has become a simplified matter of just determining the power state of each device in system to minimize power consumption. The work presented here shows an implementation of a power aware wireless sensor network. Power is measured dynamically in sensor node as certain events trigger the addition of new loads.
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    Lifetime analysis of wireless sensor nodes using queuing models
    (Dhirubhai Ambani Institute of Information and Communication Technology, 2010) Anand, Guneshwar; Srivastava, Sanjay
    Prolonging the lifetime of wireless sensor networks (WSN) is one of the key issues for wireless sensor network applications. For increasing the lifetime of network, each node should conserve its energy. Sensor nodes consume different power in different operating modes. It also consumes significant amount of power while switching from one mode to another mode. So it is important that how frequently a node is changing its mode. To address this question we have used queuing theory based control policy, which finds the optimal parameter for switching between modes. We have analysed two different control policies namely, N-policy and T-policy and their effect on the lifetime of a sensor node. In N-policy, a sensor node switches its mode only when total number of packets are N. We find an optimal value of N that minimizes the energy consumption per unit time. Similarly, in T-policy whenever system becomes empty it goes on vaccation for a fixed duration T. It changes its mode only again after T unit of time and stays in the same mode as long as there is a packet. In this case also we find the optimal value of T that minimizes the energy consumption per unit time. But this improvement in lifetime comes at the cost of longer delay and larger waiting time. We have given the expression for the latency delay. Depending on the application requirement one can tune the parameters to get the best result between the energy saving and latency delay.
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    Detection of unauthorized vehicle movement across the forest boundary using wireless sensor networks
    (Dhirubhai Ambani Institute of Information and Communication Technology, 2006) Rana, Deepika; Srivastava, Sanjay; Lenin, R. B.
    Wireless sensor network is a collection of small sensor nodes. These nodes consist of sensing, communication and computation capability that attracts a large number of applications. Wireless sensor networks are deployed for a particular application on hand and are therefore application-specific in nature. An effort has been made in this thesis work to understand the true potential of such networks by studying the on-going work in this field. A novel application has been identified that would benefit from the deployment of such network. Presence of unauthorized vehicle inside the forest premises can be detected and its information can be made available to the forest officials. Sensor network architecture has been designed for the application. Importance of placement of sensor nodes and scheduling the sensor nodes to achieve longer lifetime are also discussed. Simulation results show how the system behaves under various conditions.
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    Distributed clustering for heterogeneous wireless sensor network in data gathering applications
    (Dhirubhai Ambani Institute of Information and Communication Technology, 2005) Saxena, Nischal; Ranjan, Prabhat
    Wireless Sensor networks have revolutionized the paradigm of gathering and processing data in diverse environment such as, wildlife area, kindergarten or agriculture farm. The nodes in these networks usually have a very low and fixed amount of energy, which cannot easily be replenished, and hence there is a need for energy efficient techniques to improve the lifetime of such networks. Data Aggregation is one prominent method that is employed to reduce the amount of energy used in data transmission among the nodes in a network. This method requires hierarchical organization of the nodes. Clustering is one phenomenon that introduces the required hierarchy in a network. It also helps in increasing the lifetime of the network and its scalability as well. On the other hand the cost paid off for clustering is unbalanced energy consumption, which arises due to variations in the roles assigned to the nodes. This imbalance can lead to early partitioning of the network. Due to different amount of residual energy nodes cannot be considered same any more and a distinction has to be made on the basis of the residual energy and the assumption that nodes are identical has to be dropped. This work tries to address the self-organization of a wireless sensor network in presence of heterogeneity (presence of more than one type of nodes based on the energy), which may be due to initial deployment or by the network operations. The approach suggested in this work for clustering is basically meant for the data gathering applications. It is based on the local interaction of the nodes, which accounts for scalability. The nodes that are rich in residual energy are usually elected as cluster head. The load is balanced among the nodes by periodically exchanging the roles of the nodes and attaching a node to a cluster based on a cost function, which is dependent on the distance to the cluster head, degree of the cluster head and residual energy. Work also describes the simulation done to evaluate the performance of clustering and energy efficiency of the approach.
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    Localization of target in wireless sensor networks
    (Dhirubhai Ambani Institute of Information and Communication Technology, 2005) Sudhir, K. Venkata; Chakka, Vijaykumar
    Advances in hardware and wireless network technology have made it possible to build and deploy dense ad-hoc wireless sensor networks of nodes collecting and disseminating information. One problem that arises in ad-hoc wireless sensor networks is the inability of the nodes to locate themselves and the object (events) as well. With a motivation to solve this, we have proposed the following in this thesis: 1. Distributed algorithm for the location of sensors having omni directional radiation pattern using MMSE distance criteria. 2. A low computational complexity grid based technique to find sub set of sensors close to the event of occurrence from the reported set of sensors to query for further information. A MATLAB simulation is done for finding the closest sensor to the event of occurrence, without the knowledge of true positions of all the sensors in the field excluding those that act as anchors. The simulation shows a successful detection percentage of 55 with one-sensor query and 80 with two-sensor query. This detection percentage is close to the detection that is done with the knowledge of true sensor positions in the field.
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    Design and analysis of energy aware protocol-MPEARLE
    (Dhirubhai Ambani Institute of Information and Communication Technology, 2004) Mythili, S.; Ranjan, Prabhat
    Due to the technological advances and development in the field of micro electronic devices, the availability of compact, high-performance, customizable, intelligent devices at low cost has become reality. 'Wireless Sensor Network' (WSN) comprising such devices with customized sensors is used in monitoring the environment. The common demand of any application of WSN is the operation of the network for the guaranteed duration taking into account the limited battery capacity. The main consumer of battery power is the transceiver circuitry. In WSN, the nodes form number of multi-hop routes of different hop count leading to the destination. Strategy for load balancing uses the cost metric calculated by the residual battery energy on nodes and transmission power for all nodes on the path. Dynamic transmitter power scaling is used to reach the neighbors with bare minimum power. The main focus of this thesis is on increasing the lifetime of the network through energy-aware routing protocol. This protocol borrows some ideas from Ad hoc On demand Distance Vector and Energy Aware, Load balancing protocol for Mars Sensor Network. Though this protocol is applicable for any wireless network of ad hoc nature, the 'lifetime' metric considered is primarily for Wireless Sensor Networks due to its deployment in hostile environment where human intervention is not possible. This work includes the design and simulation of the protocol named MPEARLE. Simulations are carried out on ns-2 [VINT] and results are discussed. A decent improvement in lifetime of sensor nodes as well as that of network, better uniformity in the node energy levels and reduction in packet loss is achieved in comparison to AODA.