M Tech Dissertations

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

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2009 - 200932010 - 20124

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Now showing 1 - 7 of 7
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    FPGA implementation of multiband and multimode modem for software defined radio (SDR)
    (Dhirubhai Ambani Institute of Information and Communication Technology, 2012) Timbadiya, Jaykant; Dubey, Rahul
    Now 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 processing
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    Application of compressive sensing to tow-way relay channel estimation
    (Dhirubhai Ambani Institute of Information and Communication Technology, 2012) Nair, Rahit R.; Chakka, Vijaykumar
    An 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 proposed
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    Carrier recovery in software defined radio (SDR)
    (Dhirubhai Ambani Institute of Information and Communication Technology, 2012) Topiya, Vishal N.; Dubey, Rahul
    The work presented here, deals with the carrier synchronization in digital communication system. The transmitter and receiver are two separate circuits located at a distance end and rarely share same carrier frequency oscillator and hence it required to synchronize these two carrier frequency oscillator. This task is performed by the circuit called carrier recovery at receiver end. In this document, different sub modules required to implement carrier recovery structure at receiver end is discussed in detail and each sub module is tested separately using Xilinx® ISE tool. Then these sub modules are used as black boxes, to realize complete carrier recovery structure in Matlab Simulink® tool. By using Matlab Simulink® tool one would get better idea of signal processing at each stage of the carrier recovery structure. Then this complete carrier recovery model of Simulink® is translated to Modelsim® model and verified for functionality. Here this carrier recovery model is used for Software Defined Radio (SDR) application so the complete model of SDR is realized in Matlab Simulink® environment and recovered carrier is used for demodulation part of the SDR
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    Design of an analog phase shifter at X-band for radar and telecom applications
    (Dhirubhai Ambani Institute of Information and Communication Technology, 2012) Pariyani, Sandeep; Gupta, Sanjeev
    When examining a monthly bank account statement it is not only the number below the bottom line that matters. Whether that number has a minus or plus in front of it is also crucial. For many technical issues, the sign matters as well. In circuits, we can change the sign of the RF signal by means of phase shifters. Moreover, by using phase shifters, intermediate states between the signs (including complex values) can be set in circuits With the increasing use of wireless systems in GHz range, there is high demand for integrated phase shifters in phased arrays and MIMO on chip systems. An analog phase shifter has been designed and analyzed to meet the needs of Radar and Telecom applications. An X-band (8- 12 GHz) analog phase shifter using vector modulator principle is designed and analyzed using microstrip planar trans- mission line. The output of phase shifter at 0, 10, 45, 90, 135 and 180 has phase error in the range of 5. The input return loss is in the range of 5-7 dB and the output return loss is in the range of 5-15 dB. Also the insertion loss of the designed phase shifter is in the range of 5-8 dB. The designed phase shifter is then compared with commercially available Hittite's analog phase shifter
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    Statistical co-analysis, robust optimization and diagnosis of USB 2.0 system for signal and power integrity
    (Dhirubhai Ambani Institute of Information and Communication Technology, 2009) Tripathi, Jai Narayan; Dubey, Rahul
    Signal Integrity (SI) and Power Integrity (PI) are the most critical issues as semiconductor industry is moving towards higher operational speeds. Signal integrity and power integrity are such issues that should be looked at system level rather than looking at active and passive networks separately. System level analysis becomes a necessity when the individual subsystems work according to specifications, and even after that complete system doesn't work well. System level signal integrity and power integrity problems for high speed serial links have been taken into account in this thesis. Serial links are being used more and more rather than parallel links due to lesser skew and lower pin counts. Specifically USB 2.0 IP is used for this thesis work, but the analysis is generic for all serial links. This thesis considers SI and PI as a dual and a common model is used which considers both SI and PI. A statistical co-analysis of SI and PI for high speed serial links is used, which can be used for a cost effective solution too. Statistical methods are used for efficient simulations and to extract maximum information contents in the least simulation combinations. Based on this co-analysis, the system is diagnosed or modified for better SI and PI. In the end, reflection gain concept is also taken in to account for the diagnosis of the system. All in all, USB 2.0 system is diagnosed for better SI and PI. System level robustness analysis of high speed serial links are taken into account with effect of external environment. A strong correlation between measured and simulated results is shown. A generic methodology for SI and PI for high speed serial links is presented with complete analysis of package, board, termination, squidd card, decoupling network etc..
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    Analysis and modeling of power distribution network and decoupling network design strategies for high speed digital and analog VLSI system
    (Dhirubhai Ambani Institute of Information and Communication Technology, 2009) Pathak, Abhishek; Mandal, Sushanta; Nagpal, Raj Kumar; Nagchoudhuri, Dipankar
    Today’s high speed digital and analog VLSI systems are operating in GHz frequency range. With high switching rate of the devices, power distribution network (PDN) impedance causes ripples in power supply. If PDN is not designed properly it can cause false switching, or even it can damage the device permanently. In this thesis whole power distribution network (PDN) for VLSI system has been modeled using RLC equivalent circuits which can be run on any simulation program with integrated circuit emphasis (SPICE) based simulator. Frequency dependent RLC model for printed circuit board (PCB) and package interconnects has been generated, and effects of different geometry and material of interconnects on PDN impedance profile have been analyzed. Model is compared with electromagnetic (EM) full wave simulator both for the accuracy and CPU run time and it is found that model shows good accuracy with very less CPU run time as compared to full wave simulator which can take more than a day to simulate whole geometry. To meet the target impedance of PDN, Strategies for choosing decoupling capacitors and their placement over power plane have been analyzed. Key-words: Power Integrity, power delivery network, voltage regulator, simultaneous switching noise.
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    Channel estimation and tracking OFDM and MIMO systems
    (Dhirubhai Ambani Institute of Information and Communication Technology, 2009) Singh, Smriti; Vijaykumar, Chakka
    In this thesis, To estimate and track the slow Time varying channels in OFDM and MIMO systems. In first part: we have used a two-dimensional recursive least square adaptive channel estimation technique is used. In orthogonal frequency division multiplexing (OFDM) system, time- and frequency-domain two-dimensional minimum mean square error (2D-MMSE) channel estimation is optimum. However, accurate channel statistics, which are often time varying and unavailable in practice, are required to realize it.2DRLS adaptive channel estimation does not require accurate channel statistics, and at the same time can make full use of time and frequencydomain correlations of the frequency response of time-varying wireless channels. With properly chosen parameters, 2D-RLS adaptive channel estimation can converge into the steady state in only several OFDM symbols time. Although the 2D RLS algorithm creates adaptive letters with a fast convergence speed, this algorithm diverges when the inverse correlation matrix of input loses the properties of positive definiteness or Hermitian symmetry. The diverging of the 2D RLS algorithm same as standard RLS limits the application of this algorithm. We proposed a QR decomposition-based 2DRLS (inverse QR-2DRLS) algorithm, which can resolve this instability. Instead of propagating inverse of correlation matrix of the input signal, it propogates square root of inverse correlation matrix of the input signal. Therefore, this algorithm guarantees the property of positive definiteness and is more numerically stable than the standard RLS algorithm. The parallel implementation of the inverse QR-2DRLS algorithm permits a direct computation of the least squares weight coefficients matrix MATLAB simulations demonstrate that performance of QR-2D-RLS adaptive channel estimation is same as of 2D-RLS adaptive channel estimation and is very effective and suitable for a broad range of channel conditions. In the second part of the thesis: Since, In MIMO systems, accurate channel estimation is necessary to fully exploit the benefits of spatial diversity offered by such systems. And for time-varying channels, these channel estimates should also be updated accordigly to track the variation of channel. we have used One such method of channel estimation using adaptive SVD updates for channel estimation and tracking of slow-time varying channels in MIMO system. The channel estimates are then further used for symbol detection using V-BLAST/ZF detection algorithm which ensures interference reduction and give better BER vs. SNR performance than SVD based MIMO system.