Browsing by Author "Chen, Hao"

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    Enabling a “Use-or-Share” Framework for PAL–GAA Sharing in CBRS Networks via Reinforcement Learning
    (IEEE, 2019) Tarver, Chance; Tonnemacher, Matthew; Chandrasekhar, Vikram; Chen, Hao; Ng, Boon Loong; Zhang, Jianzhong; Cavallaro, Joseph R.; Camp, Joseph
    By implementing reinforcement learning-aided listen-before-talk (LBT) schemes over a citizens broadband radio service (CBRS) network, we increase the spatial reuse at secondary nodes while minimizing the interference footprint on higher-tier nodes. The federal communications commission encourages “use-or-share” policies in the CBRS band across the priority access license (PAL)-general authorized access (GAA) priority tiers by opportunistically allowing the lower-priority GAA nodes to access unused higher-priority PAL spectrum. However, there is currently no mechanism to enable this cross-tier spectrum sharing. In this paper, we propose and evaluate LBT schemes that allow opportunistic access to PAL spectrum. We find that by allowing LBT in a two carrier, two eNB scenario, we see upward of 50% user perceived throughput (UPT) gains for both eNBs. Furthermore, we examine the use of ${Q}$ -learning to adapt the energy-detection threshold (EDT), combating problematic topologies, such as hidden and exposed nodes. With merely a 4% reduction in primary node UPT, we see up to 350% gains in average secondary node UPT when adapting the EDT of opportunistically transmitting nodes.
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    ¿Representacion realista o vision personal? Análisis de la objectividad de Los de abajo de Mariano Azuela [Spanish Text]
    (2006) Chen, Hao; Delden, Maarten Van
    Contrary to what many critics have claimed, Mariano Azuela's descriptions of the Mexican Revolution of 1910 in Los de abajo are objective. Although the writer did reflect his pessimistic ideologies in his writings, he didn't distort reality or denigrate the revolution and its participants. The weakness and impractical nature of the intellectuals in the novel are common problems among intellectual revolutionaries of that time. The behavior of the peasants in Los de abajo reflects the characteristics of all the peasant class and can find many similarities in the Chinese peasants during the Chinese Revolution. The failure of Demetrio Macías is not determined by the pessimistic vision of Mariano Azuela but by the limitations of all the entire peasant class and by the failure of the intellectuals to provide the revolutionaries with effective guidance.
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    Representacion realista o vision personal? Analisis de la objetividad de 'Los de abajo' de Mariano Azuela
    (2006) Chen, Hao; Delden, Maarten Van
    Contrary to what many critics have claimed, Mariano Azuela's descriptions of the Mexican Revolution of 1910 in Los de abajo are objective. Although the writer did reflect his pessimistic ideologies in his writings, he didn't distort reality or denigrate the revolution and its participants. The weakness and impractical nature of the intellectuals in the novel are common problems among intellectual revolutionaries of that time. The behavior of the peasants in Los de abajo reflects the characteristics of all the peasant class and can find many similarities in the Chinese peasants during the Chinese Revolution. The failure of Demetrio Macías is not determined by the pessimistic vision of Mariano Azuela but by the limitations of all the entire peasant class and by the failure of the intellectuals to provide the revolutionaries with effective guidance.
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    Subaerial crust emergence hindered by phase-driven lower crust densification on early Earth
    (AAAS, 2024) Tang, Ming; Chen, Hao; Lee, Cin-Ty A.; Cao, Wenrong
    Earth owes much of its dynamic surface to its bimodal hypsometry, manifested by high-riding continents and low-riding ocean basins. The thickness of the crust in the lithosphere exerts the dominant control on the long-wavelength elevations of continents. However, there is a limit to how high elevations can rise by crustal thickening. With continuous crustal thickening, the mafic lower crust eventually undergoes a densifying phase transition, arresting further elevation gain—an effect clearly observed in modern orogenic belts. On early Earth, lower crust densification should also limit how high a thickening crust can rise, regardless of the thickening mechanisms. We suggest that lower crust densification combined with a thicker oceanic crust in the Archean may have limited the whole-Earth topographic relief to 3 to 5 kilometers at most—half that of the present day. Unless the oceans were far less voluminous, limited relief would inevitably lead to a water world on early Earth.