scholarly journals Joint Placement and Device Association of UAV Base Stations in IoT Networks

Sensors ◽  
2019 ◽  
Vol 19 (9) ◽  
pp. 2157 ◽  
Author(s):  
Ashfaq Ahmed ◽  
Muhammad Awais ◽  
Tallha Akram ◽  
Selman Kulac ◽  
Musaed Alhussein ◽  
...  
Keyword(s):  
Optimization Problem ◽  
Optimal Solution ◽  
Cost Effective ◽  
Low Complexity ◽  
Base Stations ◽  
Large Area ◽  
Significant Research ◽  
Minimum Number ◽  
Efficient Scheme

Drone base stations (DBSs) have received significant research interest in recent years. They provide a flexible and cost-effective solution to improve the coverage, connectivity, quality of service (QoS), and energy efficiency of large-area Internet of Things (IoT) networks. However, as DBSs are costly and power-limited devices, they require an efficient scheme for their deployment in practical networks. This work proposes a realistic mathematical model for the joint optimization problem of DBS placement and IoT users’ assignment in a massive IoT network scenario. The optimization goal is to maximize the connectivity of IoT users by utilizing the minimum number of DBS, while satisfying practical network constraints. Such an optimization problem is NP-hard, and the optimal solution has a complexity exponential to the number of DBSs and IoT users in the network. Furthermore, this work also proposes a linearization scheme and a low-complexity heuristic to solve the problem in polynomial time. The simulations are performed for a number of network scenarios, and demonstrate that the proposed heuristic is numerically accurate and performs close to the optimal solution.

scholarly journals Joint optimization of computing ratio and access points’ density for mixed mobile edge/cloud computing

2021 ◽  
Vol 2021 (1) ◽  
Author(s):  
Tianqi Jing ◽  
Shiwen He ◽  
Fei Yu ◽  
Yongming Huang ◽  
Luxi Yang ◽  
...  
Keyword(s):  
Cloud Computing ◽  
Coverage Probability ◽  
Optimization Problem ◽  
Mobile Cloud Computing ◽  
Low Complexity ◽  
Mixed Integer ◽  
Joint Optimization ◽  
Mobile Cloud ◽  
Convex Problem

AbstractCooperation between the mobile edge computing (MEC) and the mobile cloud computing (MCC) in offloading computing could improve quality of service (QoS) of user equipments (UEs) with computation-intensive tasks. In this paper, in order to minimize the expect charge, we focus on the problem of how to offload the computation-intensive task from the resource-scarce UE to access point’s (AP) and the cloud, and the density allocation of APs’ at mobile edge. We consider three offloading computing modes and focus on the coverage probability of each mode and corresponding ergodic rates. The resulting optimization problem is a mixed-integer and non-convex problem in the objective function and constraints. We propose a low-complexity suboptimal algorithm called Iteration of Convex Optimization and Nonlinear Programming (ICONP) to solve it. Numerical results verify the better performance of our proposed algorithm. Optimal computing ratios and APs’ density allocation contribute to the charge saving.

scholarly journals Caching and Placement for In-Network Caching in Device-to-Device Communications

2018 ◽  
Vol 2018 ◽  
pp. 1-9 ◽  
Author(s):  
Somayeh Soleimani ◽  
Xiaofeng Tao
Keyword(s):  
Optimization Problem ◽  
Optimal Solution ◽  
Content Delivery ◽  
Base Stations ◽  
D2d Communications ◽  
Dual Decomposition ◽  
Placement Problem ◽  
Content Discovery ◽  
Device To Device ◽  
Promising Solution

Caching content by users constitutes a promising solution to decrease the costly transmissions with going through the base stations (BSs). To improve the performance of in-network caching in device-to-device (D2D) communications, caching placement and content delivery should be jointly optimized. To this end, we jointly optimize caching decision and content discovery strategies by considering the successful content delivery in D2D links for maximizing the in-network caching gain through D2D communications. Moreover, an in-network caching placement problem is formulated as an integer nonlinear optimization problem. To obtain the optimal solution for the proposed problem, Lagrange dual decomposition is applied in order to reduce the complexity. Simulation results show that the proposed algorithm has a near-optimal performance, approaching that of the exhaustive search method. Furthermore, the proposed scheme has a notable in-network caching gain and an improvement in traffic offloading compared to that of other caching placement schemes.

scholarly journals Throughput Fairness in Cognitive Backscatter Networks With Residual Hardware Impairments and a Nonlinear EH Model

2021 ◽  
Author(s):  
Xiaona Gao ◽  
Liqin Shi ◽  
Guangyue Lu
Keyword(s):  
Iterative Algorithm ◽  
Optimization Problem ◽  
Optimal Solution ◽  
Primary User ◽  
Energy Harvesters ◽  
Hardware Impairments ◽  
Convex Problem ◽  
Resource Allocation Scheme ◽  
Nonlinear Energy

Abstract This paper is to design a throughput fairness-aware resource allocation scheme for a cognitive backscatter network (CBN), where multiple backscatter devices (BDs) take turns to modulate information on the primary signals and backscatter the modulated signals to a cooperative receiver (C-Rx), while harvesting energy to sustain their operations. The nonlinear energy harvesting (EH) circuits at the BDs and the residual hardware impairments (HWIs) at the transceivers are considered to better reflect the properties of the practical energy harvesters and transceivers, respectively. To ensure the throughput fairness among BDs, we formulate an optimization problem to maximize the minimum throughput of BDs by jointly optimizing the transmit power of the primary transmitter, the backscattering time and reflection coefficient for each BD, subject to the primary user’s quality of service (QoS) and BDs’ energy-causality constraints. We introduce the variable slack and decoupling methods to transform the formulated non-convex problem, and propose an iterative algorithm based on block coordinate descent (BCD) technique to solve the transformation problem. We also investigate a special CBN with a single BD and derive the optimal solution in the closed form to maximize the BD's throughput. Numerical results validate the quick convergence of the proposed iterative algorithm and that the proposed scheme ensures much fairness than the existing schemes.

Reliable and Cost-Effective Dispensing Technology for Large-Area Patterning

2007 ◽  
Vol 1030 ◽  
Author(s):  
Bo Li ◽  
Patrick A. Clark ◽  
Kenneth H. Church
Keyword(s):  
Flexible Electronics ◽  
Cost Effective ◽  
Great Accuracy ◽  
Global Market ◽  
Large Area ◽  
Human Scale ◽  
Significant Research ◽  
Accuracy And Repeatability ◽  
Smart Pump

AbstractIt is reported that the global market for flexible electronics will reach 250 billion dollars by 2025, driven by the products on a human scale (the so called “electronics for life”). These devices such as LCDs cannot be made smaller. However, this field is immature and significant research and development is being conducted for the synthesis, manufacture and characterization of these kinds of devices. The manufacturing process has been identified as the bottleneck of the advancement of these products. High throughput, reliable and yet cost effective technologies are greatly needed for the developing of affordable and functional devices. Researchers and engineers at nScrypt have developed enabling tools and processing solutions for patterning components on large areas with great accuracy and repeatability. In this paper, we will present innovative printing/dispensing solutions as well as novel pumping technologies (smart pump) for the manufacturing and packaging on large areas. In addition to the smart pump, we have a mixer head and spray attachment for the developing of new materials and covering large area.

scholarly journals Critical Review : Significant Impact of ICT in Higher Education Examination System

2019 ◽  
pp. 202-210
Author(s):  
Pravin Pandit Shinkar ◽  
Bechoo Lal
Keyword(s):  
Higher Education ◽  
Critical Review ◽  
Cost Effective ◽  
Examination System ◽  
Research Issues ◽  
Significant Research ◽  
On Line ◽  
Exam System

In this research article the researcher discussed the critical review and significant impact of ICT in higher education examination system. The researcher emphasized that some of the significant research issues on ICT which is having lot of possibilities in improving the whole examination system. Trend of seeking online applications for regular, examinations and conducting on-line examinations have made the system very simple and cost effective for the examining bodies. This paper presents the growing role of examinations in improving the quality of education by embracing the integrated automated exam system for providing the robust, transparent, accurate and authenticated outputs. This automated exam system through ICT will bring substantial quality improvement in education. A part from implementing ICT quality, problem in exam has also been discussed. ICT will make exam system more efficient and transparent account.

scholarly journals Performance Evaluation of Hybrid Crowdsensing and Fixed Sensor Systems for Event Detection in Urban Environments

Sensors ◽  
2021 ◽  
Vol 21 (17) ◽  
pp. 5880
Author(s):  
Matthias Hirth ◽  
Michael Seufert ◽  
Stanislav Lange ◽  
Markus Meixner ◽  
Phuoc Tran-Gia
Keyword(s):  
Hybrid Systems ◽  
Event Detection ◽  
Detection Probability ◽  
Cost Effective ◽  
Urban Environments ◽  
Sensor Data ◽  
Minimum Number ◽  
Environmental Sensor ◽  
The Given

Crowdsensing offers a cost-effective way to collect large amounts of environmental sensor data; however, the spatial distribution of crowdsensing sensors can hardly be influenced, as the participants carry the sensors, and, additionally, the quality of the crowdsensed data can vary significantly. Hybrid systems that use mobile users in conjunction with fixed sensors might help to overcome these limitations, as such systems allow assessing the quality of the submitted crowdsensed data and provide sensor values where no crowdsensing data are typically available. In this work, we first used a simulation study to analyze a simple crowdsensing system concerning the detection performance of spatial events to highlight the potential and limitations of a pure crowdsourcing system. The results indicate that even if only a small share of inhabitants participate in crowdsensing, events that have locations correlated with the population density can be easily and quickly detected using such a system. On the contrary, events with uniformly randomly distributed locations are much harder to detect using a simple crowdsensing-based approach. A second evaluation shows that hybrid systems improve the detection probability and time. Finally, we illustrate how to compute the minimum number of fixed sensors for the given detection time thresholds in our exemplary scenario.

scholarly journals The Design of Deploying RIS for Millimetre-Wave Signal in Outdoor Environment

2021 ◽  
Vol 2021 ◽  
pp. 1-6
Author(s):  
Wenming Shi ◽  
Yang Liu ◽  
Zhangyou Peng ◽  
Mengnan Xu ◽  
Zhonghao Zhang
Keyword(s):  
Wireless Communication ◽  
Optimal Solution ◽  
Low Complexity ◽  
Outdoor Environment ◽  
Coverage Problem ◽  
Coverage Area ◽  
Millimetre Wave ◽  
Cell Network ◽  
Very High

The power coverage of wireless communication is crucial for the quality of communication and cell network evaluation. In this letter, by taking the layout of Reconfigurable Intelligent Surface (RIS) into count, the power coverage area is proposed for a typical outdoor scenario, which has many rectangular buildings. In this approach, via designing the deploying angle, we introduce finding the optimal horizontal and elevation angles of RIS; we adjust RIS so as to get more power coverage. Since the computational complexity of the optimal solution is very high, a low-complexity method is proposed for solving the optimization problem. More specifically, the coverage is showed in the urban environment with RIS assisting. Presenting the numerical results, we can find the power coverage notably improved. It clearly indicates that our experiment is useful to solve the coverage problem for wireless communication.

scholarly journals Fuzzy Logic Based Coverage and Cost Effective Placement of Serving Nodes for 4G and Beyond Cellular Networks

2017 ◽  
Vol 2017 ◽  
pp. 1-25 ◽  
Author(s):  
Arthi Murugadass ◽  
Arulmozhivarman Pachiyappan
Keyword(s):  
Site Selection ◽  
Unit Area ◽  
Cost Effective ◽  
Base Stations ◽  
Term Evolution ◽  
Transmission Quality ◽  
Simulation Results ◽  
Coverage Holes

The densification of serving nodes is one of the potential solutions to maximize the spectral efficiency per unit area. This is preposterous on account of conventional base stations (BS) for which site procurement is costly. Long term evolution-advanced (LTE-A) defines the idea of heterogeneous networks (HetNets), where BSs with different coverage and capacity are utilized to guarantee the quality of service (QoS) requirements of the clients. To maximize the transmission quality of the clients in the coverage holes, LTE-A also defines multihop relay (MHR) networks, where the relay stations (RSs) are also placed along with the BSs. Unfortunately, the placement approaches for HetNet and MHR serving nodes are not standardized. In this work, two different approaches like site selection with maximum service coverage (SSMSC) and site selection with minimum placement cost (SSMPC) are proposed, which identifies the required number of serving nodes, their types, and the placement locations to maximize the coverage and to maintain the placement cost (PC) within the limits of the total placement budget. The simulation results demonstrate that the proposed approaches are computationally less complex and offer enhanced performance in terms of aggregate PC, coverage, and power proportion compared to the other conventional approaches.

scholarly journals Hierarchical Clustering as a Dimension Reduction Technique for Markowitz Portfolio Optimization

2020 ◽  
Vol 27 (1) ◽  
pp. 62-71
Author(s):  
Anatoliy Y. Poletaev ◽  
Elena M. Spiridonova
Keyword(s):  
Dimension Reduction ◽  
Portfolio Selection ◽  
Hierarchical Clustering ◽  
Optimization Problem ◽  
Pair Correlation ◽  
Optimal Solution ◽  
Optimal Portfolio ◽  
Practical Applications ◽  
Optimal Portfolio Selection

Optimal portfolio selection is a common and important application of an optimization problem. Practical applications of an existing optimal portfolio selection methods is often difficult due to high data dimensionality (as a consequence of the large number of securities available for investment). In this paper, a method of dimension reduction based on hierarchical clustering is proposed. Clustering is widely used in computer science, a lot of algorithms and computational methods have been developed for it. As a measure of securities proximity for hierarchical clustering Pearson pair correlation coefficient is used. Further, the proposed method’s influence on the quality of the optimal solution is investigated on several examples of optimal portfolio selection according to the Markowitz Model. The influence of hierarchical clustering parameters (intercluster distance metrics and clustering threshold) on the quality of the obtained optimal solution is also investigated. The dependence between the target return of the portfolio and the possibility of reducing the dimension using the proposed method is investigated too. For each considered example in the paper graphs and tables with the main results of the proposed method - application which are the decrease of the dimension and the drop of the yield (the decrease of the quality of the optimal solution) - for a portfolio constructed using the proposed method compared to a portfolio constructed without the proposed method are given. For the experiments the Python programming language and its libraries: scipy for clustering and cvxpy for solving the optimization problem (building an optimal portfolio) are used.

scholarly journals Optimization Strategy of Task Offloading with Wireless and Computing Resource Management in Mobile Edge Computing

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Xintao Wu ◽  
Jie Gan ◽  
Shiyong Chen ◽  
Xu Zhao ◽  
Yucheng Wu
Keyword(s):  
Resource Management ◽  
Optimal Solution ◽  
Edge Computing ◽  
Base Stations ◽  
Mobile Edge Computing ◽  
Optimization Strategy ◽  
Resource Allocation Algorithm ◽  
Computing Resource ◽  
Task Offloading

Mobile edge computing (MEC) provides user equipment (UE) with computing capability through wireless networks to improve the quality of experience (QoE). The scenario with multiple base stations and multiple mobile users is modeled and analyzed. The optimization strategy of task offloading with wireless and computing resource management (TOWCRM) in mobile edge computing is considered. A resource allocation algorithm based on an improved graph coloring method is used to allocate wireless resource blocks (RBs). The optimal solution of computing resource is obtained by using KKT conditions. To improve the system utility, a semi-distributed TOWCRM strategy is proposed to obtain the task offloading decision. Theoretical simulations under different system parameters are executed, and the proposed semi-distributed TOWCRM strategy can be completed with finite iterations. Simulation results have verified the effectiveness of the proposed algorithm.

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