M Tech Dissertations
Permanent URI for this collectionhttp://drsr.daiict.ac.in/handle/123456789/3
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Item Open Access Privacy preservation in vehicular ad-hoc networks (VANETs)(Dhirubhai Ambani Institute of Information and Communication Technology, 2015) Garg, Garima; Das, Manik LalVehicular Ad-hoc Networks (VANETs) are the special application of Mobile Ad-hoc Networks (MANETs). Due to increase in the number of road accidents, VANETs provide security to road traffic by sending safety messages to other vehicles. However, the safety messages provide safety from accidents, the privacy of the vehicles from adversaries is also a concern. Vehicles have to preserve the privacy of contextual information like identity of the vehicle, location of the vehicle, speed of the vehicle and route etc. Therefore, the privacy preservation of vehicle is important because by using the vehicle’s information an adversary can easily send false information to other vehicles which can cause a road accident. One of the methods to preserve privacy in VANETs is by using Pseudonym Identities (PIDs). PIDs are not real IDs of the vehicles. PIDs are different from Real Identities (RID) of vehicles. We have suggested an approach for privacy preservation in VANETs using PIDs and Certificate-Less SignCryption (CLSC) [16] scheme as cryptographic primitive. This approach is more secure over hash-chain based and certificate-based schemes. We have also simulated a hash-chain based scheme which is better than hash-chain based scheme described in [7]. However, the scheme has many limitations therefore we moved on to certificate-less based schemes after reviewing the certificate-based scheme’s limitations. The proposed scheme uses CLSC as cryptographic primitive and there are two more system components other than the vehicle, RSU and CA. The VANET system is divided into zones and each zone has a ZRSU which provide credentials to the vehicle and when a vehicle moves from its home zone to other zone handover is done. Vehicles contact to PKGC in handover phase. PKGC is situated at the separation point of two zones. The Proposed approach is secure and efficient. It provides privacy for vehicles.Item Open Access 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).Item Open Access Application of network coding in wireless sensor and relay based ad hoc networks(Dhirubhai Ambani Institute of Information and Communication Technology, 2015) Singh, Dushyant; Pillutla, Laxminarayana S.Network Coding (NC) is a new area which brings radical change in the way we treat information flow in networks. NC considered being a layer 3 operation has been shown to improve the throughput of wired networks especially for broadcast and multicast traffic. Linear network coding (LNC) in which packets are combined using simple linear operations over finite fields can indeed achieve the multicast capacity. Random LNC (RLNC) is attractively used for distributed scenario where the codes are generated by various nodes in random fashion. The data dissemination latency scales as O(N2) (N is the number of nodes) in naive broadcast scenario. However with RLNC the data dissemination latency scales between O(N) and O(N2) depending on the network connectivity. NC is at the heart of two problems that we have considered in this thesis. Firstly we consider collaborative distributed indoor target tracking using wireless sensor networks (WSNs) where we show how RLNC can be used for effective information dissemination and analyzed its impact on tracking performance for the case of indoor target tracking. Our simulation results demonstrate that for a target root mean square (RMS) value of tracking error the RLNC scheme would require less number of time slots in comparison with the two competing schemes. Secondly we consider the performance of NC in relay assisted contention based ad hoc networks considered like the IEEE 802.11 compliant ones. We specifically show as how MAC layer NC can be used at both relay, source & destination nodes to improve throughput in contention based wireless networks. Our simulation results demonstrate an increment in system throughput by 15-20% for the case with NC.Item Open Access Precision agriculture using wireless sensor network(Dhirubhai Ambani Institute of Information and Communication Technology, 2015) Joshi, Nikita Rajeshbhai; Shrivastava, SanjayFarming 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.Item Open Access Precoder design for beamforming in K-User MIMO interference chennel(Dhirubhai Ambani Institute of Information and Communication Technology, 2014) Nivedita, S.; Sunitha, V.; Chakka, Vijay KumarBeamforming in MIMO wireless networks, is a techniques used for mitigating interference and achieve the best possible throughput. Accurate channel state information is essential for efficient design of beamforming vectors required for data transmission. According to [1], if accurate channel information is available, precoding vector design problem could be reduced to a problem of Generalised Eigen Vector computation for a matrix pencil. In this thesis, it is assumed that the channel state information available is incomplete. Thus, the eigen vector computation for precoding vector design is that of a noisy matrix pencil. In [2], some SVD based techniques have been explored for eigen value and eigen vector compuatation of noisy matrix pencils, in [2], performance of these methods has been analysed assuming that the matrix pencil involved has a know structure. This thesis analyses the performance of the SVD methods for the noisy matrix pencils that are involved in K-User MIMO networks (such a matrix pencil would not have a defined structure when the channel state information available is assumed to be incomplete).Item Open Access Spectrum sensing in cognitive radio networks(Dhirubhai Ambani Institute of Information and Communication Technology, 2014) Ahir, Sagar J.; Pillutla, Laxminarayana S.In this thesis, we consider the problem of secondary users’ selection for cooperative spectrum sensing in cognitive radio networks. We assume that the secondary users involved in sensing transmit their spectral energy measurements to the fusion center. The fusion center performs maximal ratio combining (MRC) before taking a decision on the presence or absence of primary users. MRC reduces the complexity of decision rule and also facilitates in computation of the expressions for probability of detection and false alarm. Due to the discrete nature of the parameter set (which is nothing but the indices of the secondary users) and the fact that we have to work with estimates of the underlying objective function we pose the problem of secondary users’ selection under the discrete stochastic optimization framework. For this purpose we assume the objective function to be the probability of detection with the probability of false alarm set to a desired value. Owing to the high computational complexity associated with the exhaustive search, we propose an algorithm that appeared in operations research literature which spends most of its time near the global optimizer. The algorithm can also naturally track the optimal secondary users subset due to variations in channel gains. We also extend the above optimization framework to even include the case of antenna selection for cases when the secondary users are equipped with multiple antennasfor sensing. Our simulation results demonstrate the efficacy of the proposed approach.
Item Open Access FIR filter for high speed 60 GHz wireless communications.(Dhirubhai Ambani Institute of Information and Communication Technology, 2013) Dholariya, Tarun; Sen, SubhajitIn this thesis report the design and implementation of the FIR filter at 5 GS/s presented. IEEE 802.15.3c standard declared unlicensed band from 57 to 66 GHz. This 60 GHz wireless communication transmitter uses interpolator filter part of this works at 5 GS/s. In this report 6 order 5 GS/s FIR filter implementation is described. In 180nm technology speed requirement cannot be achieved. Using the 45 nm technology this FIR filter is implemented and tested. The FIR filter structure is designed in bit pipelined structure. The key part are CPL adder and TSPC Flip-Flop. These adder and FF enabled very high frequency operation at 7.35 GHz. This led to implementation of 5 GS/s FIR filter using power of 2 coefficients.Item Open Access FPGA implementation of multiband and multimode modem for software defined radio (SDR)(Dhirubhai Ambani Institute of Information and Communication Technology, 2012) Timbadiya, Jaykant; Dubey, RahulNow a days Software Defined Radio(SDR) is becoming popular for wireless communication because of it’s flexibility to change as per requirement through software. The work presented here describes the different methods of designing a Multiband and Multimode MODEM, implementation on programmable device like FPGA and verification for different functionality and specification. The design presented here has ability to switch between different modulation scheme and different data rate. Multiband and Multimode modem includes BPSK and QPSK modulator and demodulator with Forward Error Correction and other base band processingItem Open Access Application of compressive sensing to tow-way relay channel estimation(Dhirubhai Ambani Institute of Information and Communication Technology, 2012) Nair, Rahit R.; Chakka, VijaykumarAn Amplify and Forward Two-Way Relay Network is one where two nodes transmit data to each other via an intermediate relay. The relay amplifies the superimposed data from both the nodes before sending it to both the nodes. A method for the estimation of channel is proposed for Amplify and Forward Two-Way Relay Network (AF-TWRN). The proposed method utilizes the fact that the channel in the case of AF-TWRN shows sparse characteristic. The sparse multipath channel is estimated in the case of AF-TWRN using compressive sensing (CS) reconstruction algorithm, namely Iterative Hard Thresholding (IHT). MSE based performance of these methods in estimating the composite AF-TWRN channel was calculated and compared to that using Compressive Sampling Matching Pursuit (CoSaMP) and Orthogonal Matching Pursuit (OMP). IHT and CoSaMP are seen to perform slightly better than OMP with lesser computational complexity than OMP. It was also shown that all three CS based estimation methods perform better than the traditional Least Squares (LS) method in the estimation of Sparse AF-TWRN channel. A low complexity detection strategy was proposedItem Open Access Design of a novel high linearity down conversion mixer for GSM band applications(Dhirubhai Ambani Institute of Information and Communication Technology, 2012) Srinaga, Nikhil N.; Gupta, SanjeevDouble balanced Gilbert cell mixer (GCM) is the mostly used kind of mixer as it provides conversion gain and has port to port isolation. This mixer lacks in linearity and noise figure which are to be taken care in designing mixer. Linearity is important for mixer design, to get an undistorted signal at its output. Similarly noise figure of double balanced GCM is more due to more number of components and is to be decreased to add less noise to RF signal. To increase the linearity of mixer, necessary changes are to be done at transconductance stage. The linearity of the mixer proposed is increased, by making use of an additional capacitor in parallel to gate capacitance and derivative superposition method. Derivative superposition method needs more number of transistors at transconductance stage resulting in increase of parasitic capacitance, resulting in an increase of flicker noise from indirect mechanism. This flicker noise due to parasitic capacitance is reduced by placing a tuned inductor in parallel to it