scholarly journals Efficient Allocation for Downlink Multi-Channel NOMA Systems Considering Complex Constraints

Sensors ◽  
2021 ◽  
Vol 21 (5) ◽  
pp. 1833
Author(s):  
Zhengjia Xu ◽  
Ivan Petrunin ◽  
Teng Li ◽  
Antonios Tsourdos
Keyword(s):  
Channel Allocation ◽  
Combinatorial Problem ◽  
Data Rate ◽  
Channel Number ◽  
Similar Data ◽  
Stochastic Algorithm ◽  
Power Budget ◽  
Two Stage ◽  
Channel Power ◽  
Running Time

To enable an efficient dynamic power and channel allocation (DPCA) for users in the downlink multi-channel non-orthogonal multiple access (MC-NOMA) systems, this paper regards the optimization as the combinatorial problem, and proposes three heuristic solutions, i.e., stochastic algorithm, two-stage greedy randomized adaptive search (GRASP), and two-stage stochastic sample greedy (SSD). Additionally, multiple complicated constraints are taken into consideration according to practical scenarios, for instance, the capacity for per sub-channel, power budget for per sub-channel, power budget for users, minimum data rate, and the priority control during the allocation. The effectiveness of the algorithms is compared by demonstration, and the algorithm performance is compared by simulations. Stochastic solution is useful for the overwhelmed sub-channel resources, i.e., spectrum dense environment with less data rate requirement. With small sub-channel number, i.e., spectrum scarce environment, both GRASP and SSD outperform the stochastic algorithm in terms of bigger data rate (achieve more than six times higher data rate) while having a shorter running time. SSD shows benefits with more channels compared with GRASP due to the low computational complexity (saves 66% running time compared with GRASP while maintaining similar data rate outcomes). With a small sub-channel number, GRASP shows a better performance in terms of the average data rate, variance, and time consumption than SSG.

scholarly journals A Two-Stage Energy-Efficient Approach for Joint Power Control and Channel Allocation in D2D Communication

IEEE Access ◽  
2019 ◽  
Vol 7 ◽  
pp. 16940-16951 ◽  
Author(s):  
Sihan Liu ◽  
Yucheng Wu ◽  
Liang Li ◽  
Xiaocui Liu ◽  
Weiyang Xu
Keyword(s):  
Power Control ◽  
Energy Efficient ◽  
Channel Allocation ◽  
D2d Communication ◽  
Two Stage ◽  
Joint Power ◽  
Efficient Approach ◽  
Joint Power Control

scholarly journals Enhanced Dynamic Spectrum Access in UAV Wireless Networks for Post-Disaster Area Surveillance System: A Multi-Player Multi-Armed Bandit Approach

Sensors ◽  
2021 ◽  
Vol 21 (23) ◽  
pp. 7855
Author(s):  
Amr Amrallah ◽  
Ehab Mahmoud Mohamed ◽  
Gia Khanh Tran ◽  
Kei Sakaguchi
Keyword(s):  
Wireless Networks ◽  
Surveillance System ◽  
Dynamic Spectrum Access ◽  
Data Rate ◽  
Dynamic Spectrum ◽  
Transmission Power ◽  
Spectrum Access ◽  
Power Budget ◽  
Disaster Area ◽  
Post Disaster

Modern wireless networks are notorious for being very dense, uncoordinated, and selfish, especially with greedy user needs. This leads to a critical scarcity problem in spectrum resources. The Dynamic Spectrum Access system (DSA) is considered a promising solution for this scarcity problem. With the aid of Unmanned Aerial Vehicles (UAVs), a post-disaster surveillance system is implemented using Cognitive Radio Network (CRN). UAVs are distributed in the disaster area to capture live images of the damaged area and send them to the disaster management center. CRN enables UAVs to utilize a portion of the spectrum of the Electronic Toll Collection (ETC) gates operating in the same area. In this paper, a joint transmission power selection, data-rate maximization, and interference mitigation problem is addressed. Considering all these conflicting parameters, this problem is investigated as a budget-constrained multi-player multi-armed bandit (MAB) problem. The whole process is done in a decentralized manner, where no information is exchanged between UAVs. To achieve this, two power-budget-aware PBA-MAB) algorithms, namely upper confidence bound (PBA-UCB (MAB) algorithm and Thompson sampling (PBA-TS) algorithm, were proposed to realize the selection of the transmission power value efficiently. The proposed PBA-MAB algorithms show outstanding performance over random power value selection in terms of achievable data rate.

scholarly journals Joint User Pairing, Channel Assignment and Power Allocation in NOMA based CR Systems

2019 ◽  
Vol 9 (20) ◽  
pp. 4282 ◽  
Author(s):  
Zain Ali ◽  
Yanyi Rao ◽  
Wali Ullah Khan ◽  
Guftaar Ahmad Sardar Sidhu
Keyword(s):  
Power Allocation ◽  
Channel Assignment ◽  
Communication Systems ◽  
Channel Allocation ◽  
Optimization Technique ◽  
Achievable Rate ◽  
Power Budget ◽  
Secondary Users ◽  
User Pairing ◽  
Cr System

The fifth generation (5G) wireless communication systems promise to provide massive connectivity over the limited available spectrum. Various new transmission paradigms such as non-orthogonal multiple access (NOMA) and cognitive radio (CR) have emerged as potential 5G enabling technologies. These techniques offer high spectral efficiency by allowing multiple users to communicate on the same frequency channel, simultaneously. A combination of both techniques may further enhance the performance of the system. This work aims to maximize the achievable rate of a multi-user multi-channel NOMA based CR system. We propose an efficient user pairing, channel assignment and power optimization technique for the secondary users while the performance of primary users is guaranteed through interference temperature limits. The results show that, at small values of the power budget or high interference threshold, optimizing channel allocation and user pairing proves to be more beneficial than optimal power allocation to the user pairs. The proposed joint optimization technique provides promising results for all values of the power budget, interference threshold and rate requirement of the communicating users.

Research on Punctual and Energy-Efficient Train Driving Strategy Based on Two-Stage Allocation of Redundant Running Time

2021 ◽  
pp. 133-146
Author(s):  
Gaofeng Liu ◽  
Wei Li ◽  
Kang Li ◽  
Meiqi Yao ◽  
Sizhe Zhao ◽  
...  
Keyword(s):  
Energy Efficient ◽  
Two Stage ◽  
Running Time

Two-Stage Algorithm for Rapid Determination of the Bending Sequence in Sheet Metal Products

1996 ◽  
Author(s):  
B. Radin ◽  
M. Shpitalni ◽  
I. Hartman
Keyword(s):  
Sheet Metal ◽  
Rapid Determination ◽  
Low Cost ◽  
Combinatorial Problem ◽  
Two Stage ◽  
Practical Applications ◽  
Second Stage ◽  
Bending Sequence ◽  
Time Limitations

Abstract This paper presents an algorithm for solving the complex and critical problem of bending sequence in sheet metal manufacturing. Finding the bending sequence and required tool assignment presents a large combinatorial problem which is impossible to solve optimally for practical applications within a reasonable period of time. The paper presents a two-stage algorithm. The first stage finds a feasible solution based upon collision avoidance heuristics. The second stage rapidly seeks an alternative feasible sequence with a lower cost without exceeding time limitations. The algorithm is very practical because it reaches a low-cost solution quickly within computer memory limitations. In this paper, the problem is defined, the approach is presented formally, and finally, the power of the algorithm is demonstrated by solving bending sequences for real products.

Two-Stage Algorithm for Determination of the Bending Sequence in Sheet Metal Products

1997 ◽  
Vol 119 (2) ◽  
pp. 259-266 ◽  
Author(s):  
B. Radin ◽  
M. Shpitalni ◽  
I. Hartman
Keyword(s):  
Sheet Metal ◽  
Low Cost ◽  
Combinatorial Problem ◽  
Two Stage ◽  
Practical Applications ◽  
Second Stage ◽  
Metal Products ◽  
Bending Sequence ◽  
Time Limitations

This paper presents an algorithm for solving the complex and critical problem of bending sequence in sheet metal manufacturing. Finding the bending sequence and required tool assignment presents a large combinatorial problem which is impossible to solve optimally for practical applications within a reasonable period of time. The paper presents a two-stage algorithm. The first stage finds a feasible solution based upon collision avoidance heuristics. The second stage rapidly seeks an alternative feasible sequence with a lower cost without exceeding time limitations. The algorithm is very practical because it reaches a low-cost solution quickly within computer memory limitations. In this paper, the problem is defined, the approach is presented formally, and finally, the power of the algorithm is demonstrated by solving bending sequences for real products.

Long term capacity of biological activated carbon filtration for organics removal

2002 ◽  
Vol 2 (1) ◽  
pp. 139-146 ◽  
Author(s):  
P.A.C. Bonné ◽  
J.A.M.H. Hofman ◽  
J.P. van der Hoek
Keyword(s):  
Activated Carbon ◽  
Water Supply ◽  
Pilot Plant ◽  
Full Scale ◽  
Sand Filtration ◽  
Two Stage ◽  
Slow Sand Filtration ◽  
Biological Activated Carbon ◽  
Running Time ◽  
Carbon Filtration

Since March 1995 Amsterdam Water Supply has applied biological activated carbon filtration (BACF) in the treatment process of the Leiduin plant. In this plant (capacity 70 × 106 m3/y) pretreated River Rhine water is infiltrated in the dune area, west of Amsterdam, for artificial recharge. Post treatment comprises rapid sand filtration, ozonation, hardness removal, biological activated carbon filtration and slow sand filtration. At the start the carbon reactivation frequency was set at 18 months, based on removal efficiencies for AOX (adsorbable organic halogens), DOC, pesticides and micropollutants. After four years of operation of a pilot plant (10 m3/hour) in parallel with the full-scale plant, the remaining removal capacity and the break-through profile of the carbon filters was investigated. In contrast to the full-scale plant, no carbon reactivation was applied in the pilot plant during the operation of 4 years. Spiking experiments were carried out after ozonation, in the influent of the biological activated carbon filtration with a cocktail of different pesticides after 1.5, 3 and 4 years. Influent concentrations varied between 2 to 10 μg/l. Without carbon reactivation the filter effluent still complies with the Dutch drinking water standards and guide lines, as well as with the Amsterdam Water Supply standards: DOC is less than 2 mg/l (actually 1.2 mg/l) and AOX remains below 5 μg/l. After four years, with spiking concentrations of 2 μg/l still no pesticide break-through was observed in the two-stage biological activated carbon filtration process. It can be concluded that a running time of 3 years between two reactivations in the two stage biological active carbon filtration is achievable, without negatively affecting the finished water quality. Average DOC concentrations will increase up to 1.2 mg/l, from 1 mg/l with running times of 2 years. After four years or 100,000 bedvolumes the AOC content is equal to or lower than 10 μg/l after biological activated carbon filtration. With slow sand filtration at the end and as polishing step AOC will be less than 10-5 μg/l. With every extension of six months duration time a saving of Euro 305,000 on reactivation costs is possible. With every 6 month extension of the running time of the carbon filters a saving of €610,000 is realised on the reactivation costs of the Leiduin treatment plant.

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