Faculty Publications
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Publications by NITK Faculty
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Item Map and Trie based Compression Algorithm for Data Transmission(Institute of Electrical and Electronics Engineers Inc., 2020) Ghuge, S.In-text compression algorithms, a set of symbols as alphabets are defined. These alphabets are the basic building blocks of the language. Traditionally 8-bit ASCII characters are chosen as alphabets. In this paper, an approach that chooses larger symbols as alphabets is proposed. For example, in the case of the English language, a set of words and special characters are chosen as alphabets. In the case of HTML documents, HTML tags are included along with alphabets from the English language described before. Better compression results can be achieved since words have larger byte size than individual ASCII characters but still get mapped to similar-sized encodings. Compressing the data to be transmitted across networks implies less usage of network bandwidth, faster transmission of data, sending several data files over a single transfer and faster reading and writing of data. Thus, the transmission of a compressed file is cost-effective and also saves time in communication. The results prove that the proposed approach gives better file size compression concerning the compression ratio when compared with state-of-the-art algorithms. © 2020 IEEE.Item Telecommunications service providers are upgrading their network infrastructure to enhance telephony and to enable future video and data services. This discussion focuses on an access network that serves as a platform for transporting telephony and asynchronous transfer mode (ATM) data to the customer premises using fiber-in-the-loop (FITL) technology. The platform provides the building blocks that will enable service providers to furnish a wide variety of offerings, such as interactive and broadcast video, Internet access, and other high-bandwidth data communications. The platform is called the switched digital video (SDV) access network. This paper describes the SDV access network, and it also presents an example of how SDV network elements could be configured with other broadband network elements to provide an interactive video services network.(Lucent Technologies, Switched digital video access networks) Bankapur, R.J.; Beuscher, H.J.; Runyon, J.P.; Sanku, A.C.R.; Sehgal, C.S.1996Item A multichannel reservation-based channel-access protocol is investigated in this paper. The available system bandwidth is divided into distinct frequency channels. Under the protocol, one channel (the control channel) is used to exchange reservation messages and the remaining channels (the traffic channels) are used for information-bearing traffic. The performance of this scheme is compared to that of a single-channel reservation-based protocol. A simple contention-based slotted-Aloha protocol is also considered. Performance results take into account the effects of multiple-access interference on acquisition and packet errors. Results show that the reservation-based approach is advantageous under conditions of high traffic. In addition, a pacing mechanism that mitigates multiple-access interference and promotes fairness is described, and results are presented that demonstrate its effectiveness.(Baltzer Sci Publ, Unslotted multichannel channel-access protocol for distributed direct-sequence networks) Raghavan, A.R.; Baum, C.W.2004Item Radiations from double notched square patch antenna on FR4 substrate(2008) Bhardwaj, D.; Bhatnagar, D.; Sancheti, S.; Soni, B.This paper presents the radiation performance of a square patch antenna having two triangular notches on opposite edges designed on glass epoxy FR4 substrate and its performance is compared with a simple square patch antenna without any notch. The simulated results for this antenna are obtained by varying notch angle and compared with the measured results. The results indicate that square patch antenna with both notch angles equal to 168o resonates not only at two different frequencies but also offers a much higher bandwidth in comparison to a normal square patch (without notches). Both these resonance frequencies lie in the median band (3.25 to 3.85 GHz) allotted by IEEE 802.16 working group for WiMAX systems. The performance of antenna is optimized considering different conditions to obtain an antenna with dual band and high bandwidth performance. The radiation patterns, gain and radiation efficiency of antenna are also determined. © 2008 SBMO/SBMag.Item Widely programmable high-frequency active RC filters in CMOS technology(Institute of Electrical and Electronics Engineers Inc., 2009) Laxminidhi, T.; Prasadu, V.; Pavan, S.We propose a circuit technique that enables the realization of widely programmable high-frequency active RC filters in CMOS technology. A fifth-order Chebyshev ladder filter having a digitally programmable 3-dB bandwidth (from 44 to 300 MHz) is used as a vehicle to validate our ideas. The opamp uses feedforward compensation for achieving high dc gain and wide bandwidth. The integrating resistors are realized as a series combination of a triode-operated MOSFET and a fixed polysilicon resistor. A charge-pump-based servo loop servoes the integrating resistor to a stable off-chip resistor. The principle of "constant capacitance scaling"is applied to the opamp and the integrating resistors so that the shape of the frequency response is maintained when the bandwidth is scaled over a 7 7times; range. The filter core, designed in a 0.18-?m CMOS process, consumes 54 mW from 1.8-V supply and has a dynamic range of 56.6 dB. © 2009 IEEE.Item Low voltage, low power chebyshev filter in 0.18 ?m cmos technology(2013) Rekha, S.; Laxminidhi, T.This paper presents an active-RC continuous time filter in 0.18 ?m standard CMOS technology intended to operate on a very low supply voltage of 0.5 V. The filter designed, has a 5th order Chebyshev low pass response with a bandwidth of 477 kHz and 1-dB passband ripple. A low-power operational transconductance amplifier (OTA) is designed which makes the filter realizable. The OTA uses bulk-driven input transistors and feed-forward compensation in order to increase the Dynamic Range and Unity Gain Bandwidth, respectively. The paper also presents an equivalent circuit of the OTA and explains how the filter can be modeled using descriptor state-space equations which will be used for design centering the filter in the presence of parasitics. The designed filter offers a dynamic range of 51.3 dB while consuming a power of 237 ?W. © 2013 World Scientific Publishing Company.Item Low power ultra wide-band balun LNA using noise cancellation and current-reuse techniques(Elsevier Ltd, 2017) Vasudeva Reddy, K.; Girija Sravani, K.; Prashantha Kumar, P.A low power, single to differential (balun) low noise amplifier (LNA) using noise cancellation and current re-use techniques is presented for ultra wide-band applications. An upsurge balun LNA is designed using UMC 0.18-?m RF CMOS technology with an emphasis on the covenant between gain, bandwidth and power dissipation. The proposed balun exerts a differential stage on top of common gate-common source (CG-CS) stage. A CG-CS stage exploits amalgamation of CG stage (for wide-band impedance matching) and CS to curtail gain and phase imbalance, while simultaneously negating the noise and distortion of input matching transistor. The escalation of bandwidth has been accomplished using staggered tuning on CG-CS and differential stages. The stacked differential amplifier does cancellation of self noise as well as supply noise. The proposed UWB balun LNA achieves 14 dB voltage gain with agreeable input reverse isolation (S11) of <-8dB over the frequency range of 3.19–8.8 GHz. The minimum noise figure of 3.9 dB and P1dB of ?10.5 dBm while exhausting 3.8 mW from 1.2 V supply. The superlative performance of balun LNA is accomplished between 3.19 and 8.8 GHz with gain and phase errors below 0.2 dB and 0.40 respectively. The layout occupying 0.77 mm2 area. The overall pre and post layout simulations of proposed LNA shows admissible agreement with theoretical predictions. © 2017 Elsevier LtdItem Total internal reflection quasiphase matching-based broadband second harmonic generation in a plane-parallel uniaxial crystal of lithium niobate(SPIE spie@spie.org, 2018) Barma, M.D.; Deb, S.; Saha, A.The present work analytically investigates the generation of broadband second harmonic (SH) using total internal reflection (TIR) quasiphase matching technique in a plane-parallel uniaxial crystal having optic axis nonparallel with respect to the horizontal base. A computer-aided simulation has been performed using lithium niobate as the nonlinear material to determine the possibility of generating broadband SH intensity when broadband fundamental laser radiation is allowed to undergo TIR inside the crystal. The simulated results indicate a peak conversion efficiency of 5.22% with a spectral bandwidth (BW) of 116 nm, centered at 2.258 ?m in a 10-mm-long slab. The effect of variation in operating temperature, crystal length, crystal thickness, angle of deviation of optic axis, and angle of incidence of fundamental beam at the air-prism interface on efficiency and BW of resulting SH output has been studied. © 2018 Society of Photo-Optical Instrumentation Engineers (SPIE).Item A Zero Index Based Meta-Lens Loaded Wideband Directive Antenna Combined with Reactive Impedance Surface(Institute of Electrical and Electronics Engineers Inc., 2018) Majumder, B.; Kandasamy, K.; Ray, K.P.In this paper, an aperture efficient wideband high-gain patch antenna is designed using a novel multilayer-based metamaterial structure combined with a reactive impedance surface (RIS)-backed patch antenna. The metamaterial unit cell is a two-layer structure which is stacked one after other to form the overall unit cell. The microscopic behavior of the proposed unit cell has been investigated. This unit cell gives low refractive index over a wide bandwidth with a negligible loss. An RIS-backed patch antenna has been designed in the required frequency band to feed the multilayer zero-index metamaterial medium. The introduction of this surface is to provide unidirectional radiation over a wideband in the zero refractive index region. The proposed antenna gives a 14% fractional bandwidth over the $C$ - and $X$ -bands. The proposed antenna enhances the peak gain of the conventional patch antenna by an amount of 8.5 dB at 8 GHz. Finally, the antenna has been fabricated and its performance is verified experimentally. © 2013 IEEE.Item A triband circularly polarized strip and SRR-loaded slot antenna(Institute of Electrical and Electronics Engineers Inc., 2018) Paul, P.M.; Kandasamy, K.; Sharawi, M.S.In this communication, a simple and compact multiband circularly polarized (CP) slot antenna loaded with metallic strips and a split-ring resonator (SRR) is proposed. The multiband operation is obtained via exciting the SRR and copper strips by the microstrip-fed square slot antenna. The SRR resonates at 1.83 GHz, while the strips and the slot antenna provide resonances at 2.5 and 3.1 GHz. Resonant modes of loaded SRR and strips combined with the fundamental mode of the slot produce CP waves at the resonance frequencies of the proposed antenna. The proposed antenna allows for independent tuning of different bands via the use of the tilted strips and the SRR. Also, the sense of polarization at the resonance frequencies can be controlled by changing the orientation of the strips and the SRR with respect to the slot. The proposed antenna is fabricated on an FR-4 substrate of dimension 50 × 50 × 1.56 mm3. Antenna performances in terms of 10 dB return loss bandwidth, 3 dB axial ratio bandwidth, gain, and efficiency are validated experimentally and are in a good agreement with the simulated results. © 2018 IEEE.