Ubiquitous Users Research Articles

A Deep-Learning Approach to a Volumetric Radio Environment Map Construction for UAV-Assisted Networks

Providing global coverage for ubiquitous users is a key requirement of the fifth generation (5G) and beyond wireless technologies. This can be achieved by integrating airborne networks, such as unmanned aerial vehicles (UAVs) and satellite networks, with terrestrial networks. However, the deployment of airborne networks in a three-dimensional (3D) or volumetric space requires a new understanding of the propagation channel and its losses in both the areal and altitude dimensions. Despite significant research on radio environment map (REM) construction, much of it has been limited to two-dimensional (2D) contexts. This neglects the altitude-related characteristics of electromagnetic wave propagation and confines REMs to 2D formats, which limits the comprehensive and continuous visualization of propagation environment variation in spatial dimensions. This paper proposes a volumetric REM (VREM) construction approach to compute 3D propagation losses. The proposed approach addresses the limitations of existing approaches by learning the spatial correlation of wireless propagation channel characteristics and visualizing REM in areal and height/altitude dimensions using deep learning models. Specifically, the approach uses two deep learning-based models: volume-to-volume (Vol2Vol) VREM with 3D-generative adversarial networks and sliced VREM with altitude-aware spider-UNets. In both cases, knowledge of the propagation environment and transmitter locations in 3D space is used to capture the spatial and altitude dependency of the propagation channel’s characteristics. We developed the Addis dataset, a large REM dataset comprising 54,000 samples collected from the urban part of Addis Ababa, Ethiopia, to train the proposed models. Each sample of data comprises a 512-meter by 512-meter areal resolution with different 3D obstacles (buildings and terrain), 15 simulated propagation loss maps at every 3-meter altitude resolution, and 80 different 3D transmitter locations. The results of the training and testing of the proposed models reveal that the constructed VREMs are statistically comparable. In particular, the Vol2Vol approach has a minimum L1 loss of 0.01, which further decreases to 0.0084 as the line-of-sight (LoS) probability increases to 0.95.

NUMERACY SKILL USE AMONG MIDDLE-AGED AND OLDER WORKERS IN THE US

Abstract In numeric information-rich societies, numeracy is essential both at work and in everyday life (e.g., calculating a budget). Numeracy skills generally decline with aging. Thus, among middle-aged and older workers, maintaining and improving numeracy skills is crucial to securing employment as well as managing everyday life. One of the counteracting strategies is to practice numeracy. However, little is known about how and what kinds of numeracy skills are used among older workers. We analyzed a nationally representative sample of U.S. workers aged 45 to 74 (n = 3,850) from the 2012/2014/2017 Program for International Assessment of Adult Competencies (PIAAC) restricted-use-file. Six dichotomous numeracy use indicators (e.g., calculating a budget, using advanced statistics) at work and in everyday life were considered. Survey weighted latent class analysis (LCA) identified three subgroups with distinctive numeracy skill use patterns, including ubiquitous (both at work and in everyday life) users, occupational users, and non-users. For example, calculating a budget was common both in non-users (40%) and ubiquitous users (84%), whereas uncommon among occupational users (25%). Also, only ubiquitous users practiced advanced math and statistics (14%), while others did not (nearly 0%). The subsequent regression analysis revealed that higher educational attainment, higher income, certain racial group (i.e., Whites), and better self-rated health were associated with greater numeracy skill use. The lack of numeracy skill use leads to lower skill levels and, in turn, social and economic disadvantages in later life. In addition to more detailed LCA results interpretations, possible policy and educational interventions are evaluated.

Adult Numeracy Skill Practice by STEM and Non-STEM Workers in the USA: An Exploration of Data using Latent Class Analysis

ABSTRACT Adult numeracy is one of the essential skill sets to navigate through numeric information-rich labour markets in general, and STEM industries in particular. Yet, relatively little is known about how numeracy skills are used in different settings in the USA. This study examined numeracy skill use patterns of STEM and non-STEM workers at work and home. Data were obtained from the 2012/2014/2017 Program for International Assessment of Adult Competencies, USA restricted-use file. Adults who were employed and aged between 25 and 65 years old (n = 5,220) were included in this study. Latent class analysis revealed four numeracy skill use patterns: non-users, non-occupational (i.e. at home) simple numeracy users, ubiquitous numeracy users, and occupational numeracy users. Additional multinomial logistic regression analysis showed that the STEM occupation was associated with a greater likelihood of being ubiquitous users than being non-occupational simple users. Results also showed that numeracy proficiency, socioeconomic statuses (i.e. educational attainment and income), as well as demographic characteristics (i.e. gender and race/ethnicity), were predictive of the numeracy skill use patterns in terms of the level of engagement and settings. Findings from this study inform policies and interventions which promote skill engagement and improvement among workers in the USA.

Mobile Edge Computing in Space-Air-Ground Integrated Networks: Architectures, Key Technologies and Challenges

Space-air-ground integrated networks (SAGIN) provide seamless global coverage and cross-domain interconnection for the ubiquitous users in heterogeneous networks, which greatly promote the rapid development of intelligent mobile devices and applications. However, for mobile devices with limited computation capability and energy budgets, it is still a serious challenge to meet the stringent delay and energy requirements of computation-intensive ubiquitous mobile applications. Therefore, in view of the significant success in ground mobile networks, the introduction of mobile edge computing (MEC) in SAGIN has become a promising technology to solve the challenge. By deploying computing, cache, and communication resources in the edge of mobile networks, SAGIN MEC provides both low latency, high bandwidth, and wide coverage, substantially improving the quality of services for mobile applications. There are still many unprecedented challenges, due to its high dynamic, heterogeneous and complex time-varying topology. Therefore, efficient MEC deployment, resource management, and scheduling optimization in SAGIN are of great significance. However, most existing surveys only focus on either the network architecture and system model, or the analysis of specific technologies of computation offloading, without a complete description of the key MEC technologies for SAGIN. Motivated by this, this paper first presents a SAGIN network system architecture and service framework, followed by the descriptions of its characteristics and advantages. Then, the MEC deployment, network resources, edge intelligence, optimization objectives and key algorithms in SAGIN are discussed in detail. Finally, potential problems and challenges of MEC in SAGIN are discussed for future work.

A Dynamic Service Reconfiguration Method for Satellite–Terrestrial Integrated Networks

Satellite–terrestrial integrated networks (STINs) are regarded as a promising solution to meeting the demands of global high-speed seamless network access in the future. Software-defined networking and network function virtualization (SDN/NFV) are two complementary technologies that can be used to ensure that the heterogeneous resources in STINs can be easily managed and deployed. Considering the dual mobility of satellites and ubiquitous users, along with the dynamic requirements of user requests and network resource states, it is challenging to maintain service continuity and high QoE performance in STINs. Thus, we investigate the service migration and reconfiguration scheme, which are of great significance to the guarantee of continuous service provisioning. Specifically, this paper proposes a dynamic service reconfiguration method that can support flexible service configurations on integrated networks, including LEO satellites and ground nodes. We first model the migration cost as an extra delay incurred by service migration and reconfiguration and then formulate the selection processes of the location and migration paths of virtual network functions (VNFs) as an integer linear programming (ILP) optimization problem. Then, we propose a fuzzy logic and quantum genetic algorithm (FQGA) to obtain an approximate optimal solution that can accelerate the solving process efficiently with the benefits of the high-performance computing capacity of QGA. The simulation results validate the effectiveness and improved performance of the scheme proposed in this paper.

Guest editorial: Special issue on wireless computing and networking

This special issue is devoted to the new research addressing challenges in the areas of wireless computing and networking. Wireless computing and networking has enabled heterogeneous access technologies for providing services to ubiquitous users. The demanding networking environment of wireless communications imposes many challenges, such as channel estimation, network protocol design, resource management, and systematic design. Due to nonuniform spectrum allocation, various radio resource management policies, economic concerns, scarcity of radio resources, and user mobility, overcoming these issues becomes more demanding. This special issue includes ten research articles from five countries including the United States, China, South Korea, Norway, and India which covers various research issues in the areas of wireless computing and networking. These articles can be broadly classified into three categories: (1) data management and query processing in wireless networks; (2) backbone management in wireless networks; and (3) routing in wireless networks. A detailed description of the corresponding works in each category is given below.

Development of Middle Agents Mediating Ubiquitous Environment and Web Services

According to the widespread use of Web Services, composition of multiple services is becoming a main issue. BPEL was proposed as a Web Services workflow language in this context. Then, in many cases we need much interactions between a service requester and a BPEL process execution engine. However for the end user under the ubiquitous environment where the service is executed with a cellular phone or PDA, the interaction means simply a burden. The reason is: (1)it is hard to carry out the operation manually, (2)a network connection is unstable, (3)a connection charge is relatively high. In this paper, we propose middle agents between ubiquitous users and Web Services. The agents analyze BPEL, extract the interaction which the ubiquitous users would need, then produce action operators. It makes a plan in order to achieve a service request from the user. Here the planning agent can reduce operations of the user by collecting the necessary information at the beginning which will be inputted during the IP execution. We show the architecture of the agents and an example regarding ATM service, then evaluate the number of inputs, the performance, and the quantity of data transmitted on network. Finally, we consider adaptability of this approach to generic BPEL flow.

Requirements of multiregional mobile broadband satellite networks

Chiefly as a result of the phenomenal worldwide growth in the use of the Internet, a number of geostationary satellite systems have been proposed for provision of broadband multimedia-type services. The vast majority of these systems address the needs of fixed users; however, satellites can also play an important role in the deployment of mobile networks. This article describes the requirements of a multiregional network of interconnected geostationary satellites capable of providing multimedia-type services to ubiquitous and mobile users.