LDPC code-based bandwidth efficient coding schemes for wireless communications

This dissertation deals with the design of bandwidth-efficient coding schemes with Low-Density Parity-Check (LDPC) for reliable wireless communications. Code design for wireless channels roughly falls into three categories: (1) when channel state information (CSI) is known only to the receiver (2) more practical case of partial CSI at the receiver when the channel has to be estimated (3) when CSI is known to the receiver as well as the transmitter. We consider coding schemes for all the above categories. For the first scenario, we describe a bandwidth efficient scheme which uses highorder constellations such as QAM over both AWGN as well as fading channels. We propose a simple design with LDPC codes which combines the good properties of Multi-level Coding (MLC) and bit-interleaved coded-modulation (BICM) schemes. Through simulations, we show that the proposed scheme performs better than MLC for short-medium lengths on AWGN and block-fading channels. For the first case, we also characterize the rate-diversity tradeoff of MIMO-OFDM and SISO-OFDM systems. We design optimal coding schemes which achieve this tradeoff when transmission is from a constrained constellation. Through simulations, we show that with a sub-optimal iterative decoder, the performance of this coding scheme is very close to the optimal limit for MIMO (flat quasi-static fading), MIMO-OFDM and SISO OFDM systems. For the second case, we design non-systematic Irregular Repeat Accumulate (IRA) codes, which are a special class of LDPC codes, for Inter-Symbol Interference (ISI) fading channels when CSI is estimated at the receiver. We use Orthogonal Frequency Division Multiplexing (OFDM) to convert the ISI fading channel into parallel flat fading subchannels. We use a simple receiver structure that performs iterative channel estimation and decoding and use non-systematic IRA codes that are optimized for this receiver. This combination is shown to perform very close to a receiver with perfect CSI and is also shown to be robust to change in the number of channel taps and Doppler. For the third case, we look at bandwidth efficient schemes for fading channels that perform close to capacity when the channel state information is known at the transmitter as well as the receiver. Schemes that achieve capacity with a Gaussian codebook for the above system are already known but not for constrained constellations. We derive the near-optimum scheme to achieve capacity with constrained constellations and then propose coding schemes which perform close to capacity. Through linear transformations, a MIMO system can be converted into non-interfering parallel subchannels and we further extend the proposed coding schemes to the MIMO case too

Effect of CuO on Dielectric Properties of Perovskite Titanate and Hexagonal Manganite

Giant dielectric material CuO is chosen suitably to make composite with insulating SrTiO3 and semiconducting SrMnO3 by solid state reaction route. Ceramic samples of 30 & 40 wt% CuO with above parent matrix ceramics were prepared. From the XRD results it confirms the formation of perfect composites with semiconducting CuO as a secondary phase. Surface morphology study from SEM confirms the presence of both types of grains. Dielectric studies were carried out at four selected frequencies (1 kHz, 10 kHz, 100 kHz, 1 MHz). The result has shown the extraordinarily improved dielectric constant. Maxwell-Wagner polarization (interfacial polarization) was made responsible for the improved result. Dielectric loss also increased by a considerable manner

LDPC code-based bandwidth efficient coding schemes for wireless communications

This dissertation deals with the design of bandwidth-efficient coding schemes with Low-Density Parity-Check (LDPC) for reliable wireless communications. Code design for wireless channels roughly falls into three categories: (1) when channel state information (CSI) is known only to the receiver (2) more practical case of partial CSI at the receiver when the channel has to be estimated (3) when CSI is known to the receiver as well as the transmitter. We consider coding schemes for all the above categories. For the first scenario, we describe a bandwidth efficient scheme which uses highorder constellations such as QAM over both AWGN as well as fading channels. We propose a simple design with LDPC codes which combines the good properties of Multi-level Coding (MLC) and bit-interleaved coded-modulation (BICM) schemes. Through simulations, we show that the proposed scheme performs better than MLC for short-medium lengths on AWGN and block-fading channels. For the first case, we also characterize the rate-diversity tradeoff of MIMO-OFDM and SISO-OFDM systems. We design optimal coding schemes which achieve this tradeoff when transmission is from a constrained constellation. Through simulations, we show that with a sub-optimal iterative decoder, the performance of this coding scheme is very close to the optimal limit for MIMO (flat quasi-static fading), MIMO-OFDM and SISO OFDM systems. For the second case, we design non-systematic Irregular Repeat Accumulate (IRA) codes, which are a special class of LDPC codes, for Inter-Symbol Interference (ISI) fading channels when CSI is estimated at the receiver. We use Orthogonal Frequency Division Multiplexing (OFDM) to convert the ISI fading channel into parallel flat fading subchannels. We use a simple receiver structure that performs iterative channel estimation and decoding and use non-systematic IRA codes that are optimized for this receiver. This combination is shown to perform very close to a receiver with perfect CSI and is also shown to be robust to change in the number of channel taps and Doppler. For the third case, we look at bandwidth efficient schemes for fading channels that perform close to capacity when the channel state information is known at the transmitter as well as the receiver. Schemes that achieve capacity with a Gaussian codebook for the above system are already known but not for constrained constellations. We derive the near-optimum scheme to achieve capacity with constrained constellations and then propose coding schemes which perform close to capacity. Through linear transformations, a MIMO system can be converted into non-interfering parallel subchannels and we further extend the proposed coding schemes to the MIMO case too

CLINICAL TRIALS: PERSPECTIVES OF MEDICAL COMMUNITY

Objective: The objective of the study was to determine the knowledge, attitude, and perception about clinical trials (CTs) among medical community of a tertiary care institution. Methodology: This was a questionnaire-based cross-sectional study conducted in the Department of Pharmacology, Government Medical College in Central Kerala for a period of 1 year. In a sample population of 690 comprising medical undergraduates (3rd phase), residents, and doctors in Medical Education Service (MES), 309 questionnaires were distributed randomly assuming 80% response to achieve the sample size of 247. Knowledge, attitude, and perceptions were quantified with a cumulative score with a scoring scheme of +1 for a correct response/positive attitude/positive perception and 0 for an incorrect response/no response/negative attitude/negative perception. The data were analyzed using SPSS 16, the knowledge, attitude, and perception were expressed as mean score as well as proportion. Results: The response rate was 95.79%. Of the 296 completed responses, 158 (53.4%) were from medical undergraduates, 62 (20.9%) from residents, and 76 (25.7%) from doctors in MES. The mean knowledge was 14.8±3.79 (maximum score 25). The mean attitudinal score was 7.07±1.82 (maximum score 10). The mean score of the participants on perception (maximum score=10) about CTs conducted in India was 4.11±2.02 which denoted a negative perception. Conclusion: The participants had good knowledge and positive attitude about CTs, however, all the three groups of participants had negative perception about CTs currently conducted in India

Audience-Centric Natural Language Generation via Style Infusion

Adopting contextually appropriate, audience-tailored linguistic styles is critical to the success of user-centric language generation systems (e.g., chatbots, computer-aided writing, dialog systems). While existing approaches demonstrate textual style transfer with large volumes of parallel or non-parallel data, we argue that grounding style on audience-independent external factors is innately limiting for two reasons. First, it is difficult to collect large volumes of audience-specific stylistic data. Second, some stylistic objectives (e.g., persuasiveness, memorability, empathy) are hard to define without audience feedback. In this paper, we propose the novel task of style infusion - infusing the stylistic preferences of audiences in pretrained language generation models. Since humans are better at pairwise comparisons than direct scoring - i.e., is Sample-A more persuasive/polite/empathic than Sample-B - we leverage limited pairwise human judgments to bootstrap a style analysis model and augment our seed set of judgments. We then infuse the learned textual style in a GPT-2 based text generator while balancing fluency and style adoption. With quantitative and qualitative assessments, we show that our infusion approach can generate compelling stylized examples with generic text prompts. The code and data are accessible at https://github.com/CrowdDynamicsLab/StyleInfusion.Comment: 14 pages, 3 figures, Accepted in Findings of EMNLP 202

Assessment of VR Technology and its Applications to Engineering Problems

Virtual reality applications are making valuable contributions to the field of product realization. This paper presents an assessment of the hardware and software capabilities of VR technology needed to support a meaningful integration of VR applications in the product life cycle analysis. Several examples of VR applications for the various stages of the product life cycle engineering are presented as case studies. These case studies describe research results, fielded systems, technical issues, and implementation issues in the areas of virtual design, virtual manufacturing, virtual assembly, engineering analysis, visualization of analysis results, and collaborative virtual environments. Current issues and problems related to the creation, use, and implementation of virtual environments for engineering design, analysis, and manufacturing are also discussed

DUAL-WAY ELECTRIC TRACTION DRIVE FOR AN ULTRACAPACITOR PACK

A hybrid energy storage system made up of battery power unit as well as an ultra capacitor pack is recognized as. A parallel electricity-linked multi input ripper tools having a half-bridge bidirectional Electricity/Electricity cell topology is selected to link battery Or ultra capacitor storage space uses the electricity-link. The paper concentrates on modeling the suggested ripper tools for dynamic and steady condition analysis. This paper presents modeling, design and analysis of the bidirectional half-bridge Electricity/Electricity ripper tools appropriate for power electronic interface between your primary energy storage system and also the electric traction drive in hybrid electric vehicles. Averaging and linearization techniques are applied to get the averaged condition space models and small signal types of the ripper tools both in boost and buck operation modes. A qualifying criterion for sizing the ripper tools passive components in line with the enforced design specifications and constraints is highlighted. Particularly, short-circuit problems and open-circuit problems of diodes and transistors are examined. Simulation outcomes of the buck-boost ripper tools during normal functioning and under faulty the weather is presented