scholarly journals Efficient Bit Loading Algorithm for OFDM-NOMA Systems with BER Constraints

2021 ◽  
Author(s):  
Tasneem Assaf ◽  
Arafat Al-Dweik ◽  
Mohamed El Moursi ◽  
Hatem Zein El din
Keyword(s):  
Bit Error Rate ◽  
Multiple Access ◽  
Optimization Problem ◽  
Mutual Interference ◽  
Modes Of Operation ◽  
Bit Loading ◽  
User Scenario ◽  
Np Hard Problem ◽  
High Computational Complexity

This paper considers applying bit loading to multicarrier non-othogonal multiple access (NOMA) systems. The objective is to maximize the system total throughput while satisfying the users' individual quality of service (QoS) constraints. Although bit loading is generally an NP-hard problem, even for orthogonal multiple access (OMA), the mutual interference between the users and the dependence of power coefficients and modulation orders are additional challenges that add substantial complexity to the optimization problem. Therefore, we propose in this paper an efficient bit loading algorithm for multicarrier NOMA systems and compares the complexity and throughput with OMA. The obtained results show that NOMA has virtual cognition and hybrid modes of operation, NOMA/OMA, that enables NOMA to outperform OMA by 100% for the two-user scenario. The complexity of the loading process for NOMA is noticeably higher than OMA, which is due to the high computational complexity of bit error rate (BER) computation for NOMA. The obtained results show that the NOMA throughput depends on which user is loaded first, and on the initially loaded bits.

scholarly journals Efficient Bit Loading Algorithm for OFDM-NOMA Systems with BER Constraints

2021 ◽  
Author(s):  
Tasneem Assaf ◽  
Arafat Al-Dweik ◽  
Mohamed El Moursi ◽  
Hatem Zein El din
Keyword(s):  
Bit Error Rate ◽  
Multiple Access ◽  
Optimization Problem ◽  
Mutual Interference ◽  
Modes Of Operation ◽  
Bit Loading ◽  
User Scenario ◽  
Np Hard Problem ◽  
High Computational Complexity

This paper considers applying bit loading to multicarrier non-othogonal multiple access (NOMA) systems. The objective is to maximize the system total throughput while satisfying the users' individual quality of service (QoS) constraints. Although bit loading is generally an NP-hard problem, even for orthogonal multiple access (OMA), the mutual interference between the users and the dependence of power coefficients and modulation orders are additional challenges that add substantial complexity to the optimization problem. Therefore, we propose in this paper an efficient bit loading algorithm for multicarrier NOMA systems and compares the complexity and throughput with OMA. The obtained results show that NOMA has virtual cognition and hybrid modes of operation, NOMA/OMA, that enables NOMA to outperform OMA by 100% for the two-user scenario. The complexity of the loading process for NOMA is noticeably higher than OMA, which is due to the high computational complexity of bit error rate (BER) computation for NOMA. The obtained results show that the NOMA throughput depends on which user is loaded first, and on the initially loaded bits.

scholarly journals Max–Min Fairness Optimization for D2D Communications Coexisting with Cellular Networks

Electronics ◽  
2020 ◽  
Vol 9 (9) ◽  
pp. 1422
Author(s):  
Hoai Giang Nguyen ◽  
Xuan Tung Nguyen ◽  
Van Son Nguyen ◽  
Trinh Van Chien ◽  
Tien Hoa Nguyen ◽  
...  
Keyword(s):  
Spectral Efficiency ◽  
Multiple Access ◽  
Optimization Problem ◽  
Mutual Interference ◽  
D2d Communications ◽  
Power Budget ◽  
Good Service ◽  
Coverage Area ◽  
Channel Condition ◽  
Simulation Results

This paper considers a system consisting of a nonorthogonal multiple access (NOMA)-based device-to-device (D2D) communication system within a cellular network, in which the time and frequency resources are shared by everyone. In particular, D2D groups that constitute different pairs are assigned to the subchannels that the cellular users occupy. A max–min fairness optimization problem with power budget constraints is formulated and solved in this paper to reduce the mutual interference between the cellular users and D2D devices that substantially impacts that with the worst channel condition. For a low computational complexity solution, we propose the use of the bisection method together with the solution of a system of linear equalities. The proposed algorithm can provide uniformly good service to all of the cellular users and D2D devices in the coverage area by utilizing the minimal total transmit power. The simulation results indicate the effectiveness of the proposed algorithm in the improvement of the spectral efficiency of the worst user under the different widely used subchannel assignments and pairing techniques.

Imaging through Scattering Media with a Learning Based Prior

2020 ◽  
Vol 2020 (14) ◽  
pp. 306-1-306-6
Author(s):  
Florian Schiffers ◽  
Lionel Fiske ◽  
Pablo Ruiz ◽  
Aggelos K. Katsaggelos ◽  
Oliver Cossairt
Keyword(s):  
Optimization Problem ◽  
Autonomous Driving ◽  
Scattering Media ◽  
Photon Scattering ◽  
Point Spread ◽  
Spread Function ◽  
Radiative Transport Equation ◽  
Spatio Temporal ◽  
Transient Imaging

Imaging through scattering media finds applications in diverse fields from biomedicine to autonomous driving. However, interpreting the resulting images is difficult due to blur caused by the scattering of photons within the medium. Transient information, captured with fast temporal sensors, can be used to significantly improve the quality of images acquired in scattering conditions. Photon scattering, within a highly scattering media, is well modeled by the diffusion approximation of the Radiative Transport Equation (RTE). Its solution is easily derived which can be interpreted as a Spatio-Temporal Point Spread Function (STPSF). In this paper, we first discuss the properties of the ST-PSF and subsequently use this knowledge to simulate transient imaging through highly scattering media. We then propose a framework to invert the forward model, which assumes Poisson noise, to recover a noise-free, unblurred image by solving an optimization problem.

UNDER-GRADUATE STUDENTS AND THE ROLE OF E- LIBRARIES TO UPLIFT THE QUALITY OF HIGHER EDUCATION

2018 ◽  
Vol 6 (26) ◽  
Author(s):  
Dharambeer Singh
Keyword(s):  
Graduate Students ◽  
Digital Libraries ◽  
Rural Areas ◽  
Multiple Access ◽  
Information Needs ◽  
Quality Of Higher Education ◽  
Brick And Mortar ◽  
Education Status

Digital libraries, designed to serve people and their information needs in the same way as traditional libraries, present distinct advantages over brick and mortar facilities: elimination of physical boundaries, round-the-clock access to information, multiple access points, networking abilities, and extended search functions. As a result, they should be especially well-suited for the disables. However, minorities, those affected by lower income and education status, persons living in rural areas, the physically challanged, and developing countries as a whole consistently suffer from a lack of accessibility to digital libraries. This paper evaluates the effectiveness and relevance of digital libraries currently in place and discusses what could and should be done to improve accessibility to digital libraries for under-graduate students.

Analyzing of UVLC system considering the effect of water depth

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Mustafa B. Al-Deen ◽  
Mazin Ali A. Ali ◽  
Zeyad A. Saleh
Keyword(s):  
Coastal Water ◽  
Water Depth ◽  
Bit Error Rate ◽  
Multiple Input Multiple Output ◽  
Visible Light Communications ◽  
New Approach ◽  
Multiple Input ◽  
Input Multiple Output ◽  
Depth Water

Abstract This paper presents a new approach to discover the effect of depth water for underwater visible light communications (UVLC). The quality of the optical link was investigated with varying water depth under coastal water types. The performance of the UVLC with multiple input–multiple output (MIMO) techniques was examined in terms of bit error rate (BER) and data rate. The theoretical result explains that there is a good performance for UVLC system under coastal water.

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.

Engine Mount Optimization for Vibration Isolation in Motorcycles

2006 ◽  
Author(s):  
Sudhir Kaul ◽  
Anoop K. Dhingra ◽  
Timothy G. Hunter
Keyword(s):  
Optimization Problem ◽  
Vibration Isolation ◽  
Total Force ◽  
Engine Mounts ◽  
The Road ◽  
Design Variables ◽  
Swing Arm ◽  
Engine Mount ◽  
Six Degree Of Freedom

This paper presents a comprehensive model to capture the dynamics of a motorcycle system in order to evaluate the quality of vibration isolation. The two main structural components in the motorcycle assembly - the frame and the swing-arm - are modeled using reduced order finite element models; the power-train assembly is modeled as a six degree-of-freedom (DOF) rigid body connected to the frame through the engine mounts and to the swing-arm through a shaft assembly. The engine mounts are modeled as tri-axial spring-damper systems. Models of the front-end assembly as well as front and rear tires are also included in the overall model. The complete vehicle model is used to solve the engine mount optimization problem so as to minimize the total force transmitted to the frame while meeting packaging and other side constraints. The mount system parameters - stiffness, position and orientation vectors - are used as design variables for the optimization problem. The imposed loads include forces and moments due to engine imbalance as well as loads transmitted due to irregularities in the road surface through the tire patch.

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