Browsing by Author "Yang, Chun-Chieh"

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A Low Overhead Queue Status Report Scheme for QoS Support in WLANs
(2009)
Lee, Tsern-Huei
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Huang, Yu-Wen
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Yang, Chun-Chieh
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電信工程研究所
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Institute of Communications Engineering
HCF Controlled Channel Access (HCCA), defined in the IEEE 802.11e document, provides a sample scheduler to allocate transmission opportunity (TXOP) to QoS-aware stations (QSTAs). Since the calculation of TXOP duration is based on mean data rate, it is efficient for constant bit rate (CBR) traffic. For variable bit rate (VBR) traffic, however, delay bound of some admitted traffic flows may be violated. Several previous works suggested that, through reporting queue status to schedulers, each QSTA can be allocated sufficient transmission opportunity (TXOP) for its buffered packets to meet delay bound requirement. However, timely queue status reports may cause considerable overheads and lead to inefficient bandwidth utilization. In this paper, we propose a low overhead queue status report scheme based on multi-polling technique and earliest deadline first policy (EDF) to provide QoS support. Simulation results show that our proposed scheme can not only meet the QoS requirements but also manage the bandwidth more efficiently than previous works.
Analyzing OpenCL 2.0 Workloads Using a Heterogeneous CPU-GPU Simulator
(2017-01-01)
Wang, Li
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Tsai, Ren-Wei
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Wang, Shao-Chung
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Chen, Kun-Chih
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Wang, Po-Han
Heterogeneous CPU-GPU systems have recently emerged as an energy-efficient computing platform. A robust integrated CPU-GPU simulator is essential to facilitate researches in this direction. While few integrated CPU-GPU simulators are available, similar tools that support OpenCL 2.0, a widely used new standard with promising heterogeneous computing features, are currently missing. In this paper, we extend the existing integrated CPU-GPU simulator, gem5-gpu, to support OpenCL 2.0. In addition, we conduct experiments on the extended simulator to see the impact of new features introduced by OpenCL 2.0. Our OpenCL 2.0 compatible simulator is successfully validated against a state-of-the-art commercial product, and is expected to help boost future studies in heterogeneous CPU-GPU systems.
Mode Switching of High Index Contrast Photonic Crystal Surface Emitting Lasers
(2016-05)
Hong, Kuo-Bin
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Yang, Chun-Chieh
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Lu, Tien-Chang
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光電工程學系
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Department of Photonics
This paper investigates the phenomenon of mode switching for GaAs-based high index contrast photonic crystal surface emitting lasers (PCSELs) with deeply etched air holes. The room-temperature lasing characteristics and angular resolved photoluminescence spectra of PCSELs show that the lasing mode would change from the fundamental guided mode to a high-order guided mode as the filling factor (FF) increased, resulting from the diffraction of deeply etched semiconductor/air arrays with high index contrast. Higher order guided modes could coherently couple out of photonic crystal and would significantly influence the laser output of PCSELs with a larger air FF, leading to rich far-field characteristics.
Optical characteristics of GaAs-based high index contrast photonic crystal lasers with deeply-etched air holes
(2016)
Hong, Kuo-Bin
;
Yang, Chun-Chieh
;
Lu, Tien-Chang
;
光電工程學系
;
Department of Photonics
We study the mode switching behavior of GaAs-based high index contrast photonic crystal lasers influenced by deeply-etched air holes. Higher order guiding waves could coherently couple out of photonic crystal and affect the laser output characteristics which are observed by angular resolved photoluminescence spectra when the air filling factor increased.