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- Nguyen, Minh-Hien T., et al.
(författare)
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Real-Time Optimized Clustering and Caching for 6G Satellite-UAV-Terrestrial Networks
- 2024
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Ingår i: IEEE transactions on intelligent transportation systems (Print). - : Institute of Electrical and Electronics Engineers (IEEE). - 1524-9050 .- 1558-0016. ; 25:3, s. 3009-3019
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, we consider an Internet-of-Things network supported by several satellites and multiple cache-assisted unmanned aerial vehicles (UAVs). Due to the long-distance transmission and detrimental effects from the transmission environment, the latency can be extremely high, especially in the presence of backhaul congestion. Therefore, we formulate an optimisation problem with the aim of minimising the total network latency. To reduce the complexity of the original problem, it is divided into three sub-problems, namely, clustering ground users associated with UAVs, cache placement in UAVs (to support the network in avoiding backhaul congestion), and power allocation for satellites and UAVs. We propose a distributed optimisation method consisting of: a non-cooperative game is designed to obtain the solution to the clustering problem; a genetic algorithm, which is powerful in the scenario of many variables, is employed to obtain the optimal solution to the high-complexity caching problem; and a quick estimation technique is used for power allocation. Additionally, a centralised optimisation method is presented as a benchmark. Simulation results show that although the distributed method leads to network latency of approximately 30% higher than the centralised method, it takes significantly less time to execute and is suitable for systems requiring strict real-time computing constraints. Furthermore, the numerical results prove the efficiency of our methods compared with other conventional ones. IEEE
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| 2. |
- Nguyen, Thi Ngoc Phuong, 1993, et al.
(författare)
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Patterns and determinants of tobacco purchase behaviors among male cigarette smokers in Vietnam: A latent class analysis
- 2024
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Ingår i: TOBACCO INDUCED DISEASES. - 1617-9625. ; 22
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Tidskriftsartikel (refereegranskat)abstract
- INTRODUCTION Understanding smokers' purchasing patterns can aid in customizing tobacco control initiatives aimed at reducing the tobacco smoking prevalence. Therefore, this study identified cigarette purchase behavior among Vietnamese male smokers and associated demographic and consumption factors. METHODS We analyzed a secondary dataset of male current tobacco smokers (n=3983) who participated in the Vietnam Global Adult Tobacco Survey in 2015. We applied the latent class analysis (LCA) to identify the classes of purchase behavior among cigarette smokers (n=1241). Multinomial logistic regression was performed to identify demographics (education level, ethnicity, partnership status, and household socioeconomic status) and cigarette consumption variables (smoking years and heavy smoking status) related to purchase behavior classes. The results are reported as an adjusted relative risk ratio (ARRR). RESULTS The LCA identified four cigarette purchase behaviors classes: Class 1 (priceinsensitive and purchased international brand: 44.4%), Class 2 (price -sensitive and purchased domestic brand: 27.6%), Class 3 (price -sensitive and purchased cigarettes in a street vendor: 18.6%), and Class 4: price -sensitive and purchased loose/carton cigarette: 9.4%). The poorer economic groups were more likely to belong to the three price -sensitive classes. Heavy smokers and those who had smoked for a longer period were more likely to belong to Class 3 (ARRR=2.33; 95% CI: 1.51-3.58 and ARRR=1.02; 95% CI: 1.001-1.05, respectively) and Class 4 (ARRR=2.94; 95% CI: 1.71-5.06 and ARRR=1.05; 95% CI: 1.02-1.08, respectively). CONCLUSIONS Varied purchasing behaviors among male cigarette smokers, influenced by divergent price sensitivities and economic backgrounds, underscore the need for comprehensive tobacco control. Future efforts should include targeted policy interventions, behavior modification, and reshaping social norms.
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