Outage performance analysis of non-orthogonal multiple access with time-switching energy harvesting

In recent years, although non-orthogonal multiple access (NOMA) has shown its potentials thanks to its ability to enhance the performance of future wireless communication networks, a number of issues emerge related to the improvement of NOMA systems. In this work, we consider a half-duplex (HD) relaying cooperative NOMA network using decode-and-forward (DF) transmission mode with energy harvesting (Ell) capacity, where we assume the NOMA destination (D) is able to receive two data symbols in two continuous time slots which leads to the higher transmission rate than traditional relaying networks. To analyse EH, we deploy time-switching (TS) architecture to comprehensively study the optimal transmission time and outage performance at D. In particular, we are going to obtain closed-form expressions for outage probability (OP) with optimal TS ratio for both data symbols with both exact and approximate forms. The given simulation results show that the placement of the relay (R) plays an important role in the system performance.Web of Science253918

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

Improving performance of far users in cognitive radio: Exploiting NOMA and wireless power transfer

In this paper, we examine non-orthogonal multiple access (NOMA) and relay selection strategy to benefit extra advantage from traditional cognitive radio (CR) relaying systems. The most important requirement to prolong lifetime of such network is employing energy harvesting in the relay to address network with limited power constraint. In particular, we study such energy harvesting CR-NOMA using amplify-and-forward (AF) scheme to improve performance far NOMA users. To further address such problem, two schemes are investigated in term of number of selected relays. To further examine system performance, the outage performance needs to be studied for such wireless powered CR-NOMA network over Rayleigh channels. The accurate expressions for the outage probability are derived to perform outage comparison of primary network and secondary network. The analytical results show clearly that position of these nodes, transmit signal to noise ratio (SNR) and power allocation coefficients result in varying outage performance. As main observation, performance gap between primary and secondary destination is decided by both power allocation factors and selection mode of single relay or multiple relays. Numerical studies were conducted to verify our derivations.Web of Science1211art. no. 220

REQUIREMENTS IN THE PROCESS OF BUILDING A CONTINGENT OF ETHNIC MINORITY CADRES IN THE MOUNTAINOUS AREAS OF NGHE AN PROVINCE, VIETNAM

Nghe An is a province in Vietnam, with 10 mountainous districts and 1 mountainous town, accounting for 83.31% of the province's natural area. The mountainous area of Nghe An is a place with complicated and dangerous terrain and poor infrastructure; the lowest human development index (HDI) in the province; economic situation is extremely difficult, but it is a place with an important strategic position in terms of socio-economic development and protection of national border security. Therefore, building a contingent of ethnic minority cadres has a very important position and role in the development of the mountainous area of Nghe An. However, the work of building a contingent of ethnic minority cadres in mountainous districts of Nghe An currently has many shortcomings and limitations that need to be overcome, and possible solutions are needed so that the construction building a contingent of ethnic minority cadres in mountainous areas to achieve good results in the coming time.  Article visualizations

TASK-BASED LANGUAGE TEACHING IN VIETNAM: RESEARCH TRENDS, FINDINGS, AND IMPLICATIONS

It is widely assumed that task-based language teaching (TBLT) has been effectively applied in EFL contexts. In Vietnam, abundant research has been implemented to examine its effects on English proficiency as well as to identify perceptions and attitudes of both teachers and learners towards using this approach in classroom contexts. This paper aims to synthesize trends in research on task-based language teaching in the context by reviewing results extracted from a corpus of 60 studies. Key aspects like effects, challenges, teacher/learner perceptions and attitudes were selected for analysis and synthesis. The results revealed that the research tended to focus more on production skills than receptive skills, and that the implementation of TBLT was reported to cause challenges for teachers, while learners tended to hold positive attitudes toward the approach. Based on the research findings, some lessons were drawn for pedagogy and future research. For successful TBLT implementation, it is suggested that teachers are informed of the effects, engaged in reflections and that exams should be shifted towards communicative competence assessment. Future research could increase sample size and treatment duration, and especially address the challenges teachers, as the main agent, encounter in implementation.  Article visualizations

Obscurant and Radiation Characteristics of Infrared Screening Smoke Composition Based on Red Phosphorus

Red phosphorus-based camouflage compositions are often used on naval ships to counter anti-ship missiles. This work focused on investigating the obscurant and infrared radiation characteristics of infrared-screening smoke of pyrotechnic compositions based on red phosphorus, Mg-Al alloy, barium nitrate and Viton A rubber. The results demonstrated that the smoke clouds of the formulation based on red phosphorus and Mg-Al alloy have a high attenuation capability to 1.064 µm laser radiation. Besides, these smokescreens also have a better emission power in the wavelength range of 2.5-5 and 8-14 µm. Therefore, the smoke compositions based on red phosphorus and Mg-Al alloy can be used in camouflage devices on naval ships against infrared and laser-guided missiles

HO CHI MINH’S VIEW ON THE TRAINING OF CADRES OF ETHNIC MINORITIES IN VIETNAM

During his revolutionary activities, Ho Chi Minh paid particular attention to ethnic minorities - political subjects mainly in highland, remote and border areas. Appreciating the critical position of the mountainous region - which has a vital role in terms of economy, politics, foreign affairs and national defence; is the location of a “revolutionary base”, “where many ethnic minorities live”, “a place contiguous with neighbouring countries”. Ho Chi Minh always cares about this strategic area and gives special affection to the people of Vietnam's ethnic minorities. In particular, Ho Chi Minh took great care in training ethnic minority cadres to “make the ethnic groups gradually manage their affairs”.  Article visualizations