Wireless Powered Cooperative Relaying using NOMA with Imperfect CSI

The impact of imperfect channel state (CSI) information in an energy harvesting (EH) cooperative non-orthogonal multiple access (NOMA) network, consisting of a source, two users, and an EH relay is investigated in this paper. The relay is not equipped with a fixed power source and acts as a wireless powered node to help signal transmission to the users. Closed-form expressions for the outage probability of both users are derived under imperfect CSI for two different power allocation strategies namely fixed and dynamic power allocation. Monte Carlo simulations are used to numerically evaluate the effect of imperfect CSI. These results confirm the theoretical outage analysis and show that NOMA can outperform orthogonal multiple access even with imperfect CSI.Comment: 6 pages, 6 figures, accepted in IEEE GLOBECOM 2018 NOMA Worksho

Enabling non-linear energy harvesting in power domain based multiple access in relaying networks: Outage and ergodic capacity performance analysis

The Power Domain-based Multiple Access (PDMA) scheme is considered as one kind of Non-Orthogonal Multiple Access (NOMA) in green communications and can support energy-limited devices by employing wireless power transfer. Such a technique is known as a lifetime-expanding solution for operations in future access policy, especially in the deployment of power-constrained relays for a three-node dual-hop system. In particular, PDMA and energy harvesting are considered as two communication concepts, which are jointly investigated in this paper. However, the dual-hop relaying network system is a popular model assuming an ideal linear energy harvesting circuit, as in recent works, while the practical system situation motivates us to concentrate on another protocol, namely non-linear energy harvesting. As important results, a closed-form formula of outage probability and ergodic capacity is studied under a practical non-linear energy harvesting model. To explore the optimal system performance in terms of outage probability and ergodic capacity, several main parameters including the energy harvesting coefficients, position allocation of each node, power allocation factors, and transmit signal-to-noise ratio (SNR) are jointly considered. To provide insights into the performance, the approximate expressions for the ergodic capacity are given. By matching analytical and Monte Carlo simulations, the correctness of this framework can be examined. With the observation of the simulation results, the figures also show that the performance of energy harvesting-aware PDMA systems under the proposed model can satisfy the requirements in real PDMA applications.Web of Science87art. no. 81

Government Support and Firm Profitability in Vietnam

Existing studies on the linkage between government subsidies and firm financial performance often use a mean regression approach and focus mainly on developed countries. To fill the gap, this study, for the first time, considers the impact of government support activities on the profitability of manufacturing SMEs in a developing country, Vietnam. Using an unbalanced panel dataset covering the period 2009–2015, government financial supports show an insignificant linkage with firm profitability when using OLS. However, a fixed-effect quantile approach reveals that government financial support is negatively related for firms with low profit but is positively related for firms in the high profitability percentile. Our findings also suggest that policymakers should focus on helping start-ups instead of ineffective, informal firms

Investigation on energy harvesting enabled device-to-device networks in presence of co-channel interference

Energy harvesting from ambient radio-frequency (RF) sources has been a novel approach for extending the lifetime of wireless networks. In this paper, a cooperative device-to-device (D2D) system with the aid of energy-constrained relay is considered. The relays are assumed to be able to harvest energy from information signal and co-channel interference (CCI) signals broadcasted by nearby traditional cellular users and forward the source’s signal to its desired destination (D2D user) utilizing amplify-andforward (AF) relaying protocol. Time switching protocol (TSR) and power splitting protocol (PSR) are proposed to assist energy harvesting and information processing at the relay. The proposed approaches are applied in a model with three nodes including the source (D2D user), the relay and the destination (D2D user), the system throughput is investigated in terms of the ergodic capacity and the outage capacity, where the analytical results are obtained approximately. Our numerical results verify the our derivations, and also points out the impact of CCI on system performance. Finally, this investigation provide fundamental design guidelines for selecting hardware of energy harvesting circuits that satisfies the requirements of a practical cooperative D2D system

Carbon assessment for Robusta coffee production systems in Vietnam: a case study in Dak Lak

Carbon assessments have proliferated to identify climate friendly practices in Arabica producing systems, though little attention is given to Robusta. In this study, we evaluated the climate impact of Robusta production via quantification of carbon stock and greenhouse gas (GHG) emissions in the intensive shaded and unshaded coffee farms of the world’s largest Robusta producing region, Vietnam’s Central Highlands. We find due to the linear relationship between fertilizer use and yields, emissions from input use on a per unit product basis are not significantly different between the intensive and less intensive systems. However, when accounting for carbon sequestered in shade and coffee trees, the less intensive systems are carbon positive (sequestering more than they emit) per unit of green coffee bean produced

Real-Time 6DOF Pose Relocalization for Event Cameras with Stacked Spatial LSTM Networks

We present a new method to relocalize the 6DOF pose of an event camera solely based on the event stream. Our method first creates the event image from a list of events that occurs in a very short time interval, then a Stacked Spatial LSTM Network (SP-LSTM) is used to learn the camera pose. Our SP-LSTM is composed of a CNN to learn deep features from the event images and a stack of LSTM to learn spatial dependencies in the image feature space. We show that the spatial dependency plays an important role in the relocalization task and the SP-LSTM can effectively learn this information. The experimental results on a publicly available dataset show that our approach generalizes well and outperforms recent methods by a substantial margin. Overall, our proposed method reduces by approx. 6 times the position error and 3 times the orientation error compared to the current state of the art. The source code and trained models will be released.Comment: 7 pages, 5 figure

Uma pesquisa-ação de 3 anos em uma universidade vietnamita: Alunos como cogeradores de conteúdo das aulas

In the context of the 4th Industrial Revolution with unlimited technological advancement and innovation, how can educators innovate their teaching and facilitate their students in their learning process, so that students can accumulate required skills and achieve the set learning outcomes of each course they take? In order to find out the answer, the authors have revised some literature concerning BYOD trend, active learning strategies, flipped classroom and learner-generated content as the theoretical base for their study. Action research has been conducted at a Vietnamese university with the participation of English-majored students in Theory of English Translation and Interpreting classes from 3 different intakes. The findings include students’ positive perception towards the content-generation practices. Some achievements and challenges in the teaching and learning process have also been reported. This paper also recommends further studies so that the practice could be utilized to the best outcomes.En el contexto de la Cuarta Revolución Industrial con un avance tecnológico e innovación ilimitados, ¿cómo pueden los educadores innovar su enseñanza y facilitar a sus estudiantes su proceso de aprendizaje, para que los estudiantes puedan acumular las habilidades requeridas y lograr los resultados de aprendizaje establecidos en cada curso que toman? Para encontrar la respuesta, los autores han revisado cierta literatura sobre la tendencia BYOD, las estrategias de aprendizaje activo, el aula invertida y el contenido generado por el alumno como base teórica para su estudio. Se llevó a cabo una investigación de acción en una universidad vietnamita con la participación de estudiantes con especialización en inglés en clases de Teoría de la traducción e interpretación en inglés de 3 tomas diferentes. Los hallazgos incluyen la percepción positiva de los estudiantes hacia las prácticas de generación de contenidos. También se reportan algunos logros y desafíos en el proceso de enseñanza y aprendizaje. Este documento también recomienda más estudios para que la práctica pueda utilizarse con los mejores resultados.No contexto da 4ª Revolução Industrial, com avanço tecnológico e inovação ilimitados, como os educadores podem inovar seu ensino e facilitar seus alunos em seu processo de aprendizagem, para que os alunos possam acumular as habilidades necessárias e alcançar os resultados de aprendizagem definidos de cada curso que fazem? Para encontrar a resposta, os autores revisaram alguma literatura sobre a tendência BYOD, estratégias de aprendizagem ativa, sala de aula invertida e conteúdo gerado pelo aluno como base teórica para seu estudo. Uma pesquisa-ação foi realizada em uma universidade vietnamita com a participação de alunos formados em inglês nas aulas de Teoria da Tradução e Interpretação do Inglês de 3 diferentes entradas. Os resultados incluem a percepção positiva dos alunos em relação às práticas de geração de conteúdo. Algumas conquistas e desafios no processo de ensino e aprendizagem também foram relatados. Este artigo também recomenda mais estudos para que a prática possa ser utilizada para os melhores resultados