23 research outputs found
Optimizing Communication Beamforming for New Multiple Access under Low-Resolution Quantization: A Spectral and Energy Efficiency Perspective
No full textDepartment of Electrical EngineeringCurrently, there is growing interest in 6G wireless communication beyond the era of 5G. In addition, the hardware devices require high-speed wireless communication and low-power communications. For example, there are applications such as the internet-of-things (IoT), where devices are limited by battery capacity and have low computing capabilities but require high spectral efficiency. In order to address the issue of power consumption in wireless communication, low-power hardware such as low-resolution analog-to-digital converter (ADC) and digital-to-analog converter (DAC) systems are having attention as a promising transceiver architecture. This is because the power consumption of quantizers decreases exponentially as the number of quantization bits decreases. In this dissertation, low-resolution quantizer system is considered to achieve the trade-off between high spectral efficiency and energy efficiency. Another challenge that needs to be addressed in the development of 6G wireless communications is the severe inter-user interference resulting from the exponential increase in the number of smart devices. For example, in IoT communications, the large number of IoT devices and high channel correlation among them can lead to a significant amount of inter-user interference, which in turn can cause considerable degradation in spectral performance. In this regard, new multiple access approaches are introduced such as rate-splitting multiple access (RSMA), non-orthogonal multiple access (NOMA), spatial-division multiple access (SDMA), and orthogonal multiple access (OMA) to control the interuser interference. Specifically, I consider rate-splitting multiple access to boost the spectral efficiency because rate-splitting multiple access provides extra achievable antenna degree-of freedom by dividing the messages into common and private messages. It is difficult to optimize rate-splitting multiple access precoders due to the minimum rate constraint involved in determining the common rate. Furthermore, the designing quantized precoders is more highly challenging to solve the optimization problem. In this dissertation, I develop a promising RSMA precoder algorithm coupled with quantization errors to maximize the spectral efficiency. To make the optimization problem in smooth function, I first approximate the spectral efficiency of common stream utilizing the Log-Sum Exp technique. Then, I derive the first-order optimality condition in terms of the nonlinear eigenvalue problem (NEP). I suggest computationally efficient method to find a sub-optimal solution for obtaining the principal eigen-vector of the nonlinear eigenvalue problem. In addition, I propose the weighted minimum mean square error-based RSMA precoding algorithm to the considered quantization system. Simulation results demonstrate the performance of the proposed algorithm in terms of the spectral efficiency, and more importantly, ratesplitting multiple access can achieve key benefit than spatial-division multiple access by balancing between the channel gain and quantization error utilizing the common stream in multiuser MIMO systems.clos
Low-power, bio-inspired time-stamp-based 2-d optic flow sensor for artificial compound eyes of micro air vehicles
No full text© 2001-2012 IEEE.We report a low-power, bio-inspired mixed-signal 2-D optic flow sensor to realize artificial compound eyes, which can provide a wide field of view (FoV) sensing capability for autonomous navigation of micro-Air-vehicles (MAVs). Inspired by insect vision, a 2-D time-stamp algorithm has been developed to scale the number of deployable sensors at low power. The fabricated sensor estimates 16-b 2-D optic flows of maximum 1.96 rad/s with FoV of 60° from the integrated mixed-signal algorithm core, which consumes only 243.3 pJ/pixel ∼ 30 μ at 120 fps. In addition, the peripheral circuits for modular design have been integrated on chip to provide optic flow data compression, wide-field integration (WFI), and serial peripheral interface (SPI). More than 25 sensors can be connected in a single SPI bus and transmit the full resolution optic flows. The fabricated prototype sensor supports full resolution 2-D optic flows from an array of 64×64 pixels at 120 fps through a 3 MB/s SPI bus (4 wires total)11sciescopu
A 1.36μW adaptive CMOS image sensor with reconfigurable modes of operation from available energy/illumination for distributed wireless sensor network
No full text7.2 243.3pJ/pixel bio-inspired time-stamp-based 2D optic flow sensor for artificial compound eyes
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#x00B5;W CMOS image sensor with embedded feature-extraction algorithm for motion-triggered object-of-interest imaging
No full textArea-efficient and low-power implementation of vision chips using multi-level mixed-mode processing
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Brief guide to gene cloning
No full textAnalysis and manipulation of DNA is fundamental to understand gene function and expression. Gene cloning is a routine and versatile technique for molecular biology, allowing isolation, amplification, and production of recombinant DNA molecules. Here, we provide an overall process, various types, and applications of gene cloning. This concise guide will be useful for researchers who are unfamiliar with gene cloning, focusing on key principles and experimental considerations (c) 2025 The Author(s). Published by Elsevier Inc. on behalf of Korean Society for Molecular and Cellular Biology. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
