Browsing by Author "Wu, Che-Wen"

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A latency and modulation aware bandwidth allocation algorithm for WiMAX base stations
(2008)
Lin, Yi-Neng
;
Wu, Che-Wen
;
Lin, Ying-Dar
;
Lai, Yuan-Cheng
;
交大名義發表
The mobile WiMAX systems based on IEEE 802.16e-2005 provide high data rate for the mobile wireless network. However, the link quality is frequently unstable owing to the long-distance and air interference and therefore impacts real-time applications. Thus, a bandwidth allocation algorithm. IS required to be modulation-aware, while further satisfying the latency guarantee, service differentiation and fairness. This work proposes the Highest Urgency First (HUF) algorithm to conquer the above challenges by taking into consideration the adaptive modulation and coding scheme (MCS) and the urgency of requests. Downlink and uplink sub-frames are determined by reserving the bandwidth for the most urgent requests am: proportionating the remaining bandwidth for others. Then independently in the downlink and uplink, the HUF allocates bandwidth to every mobile station according to a pre-calculated U-factor which considers urgency, priority and fairness. Simulation results prove the HUF is modulation-aware and achieves the above three objectives, notably the zero violation rate within system capacity as well as the throughput paralleling to the best of the existing approaches.
Highest Urgency First (HUF): A latency and modulation aware bandwidth allocation algorithm for WiMAX base stations
(2009-02-12)
Lin, Yi-Neng
;
Lin, Ying-Dar
;
Lai, Yuan-Cheng
;
Wu, Che-Wen
;
交大名義發表
The mobile WiMAX systems based on IEEE 802.16e-2005 provide high data rate for mobile wireless networks. However, the link quality is frequently unstable owing to mobility and air interference and therefore impacts the latency requirement of real-time applications. In the WiMAX standard, the modulation/coding scheme and the boundary of uplink/downlink sub-frames could be adjusted subject to channel quality and the traffic volume, respectively. This provides us a chance to design a MAC-layer uplink/downlink bandwidth allocation algorithm that is QoS/PHY-aware. This work takes into account the adaptive modulation and coding scheme (MCS), uplink and downlink traffic volume, and QoS parameters of all five defined service classes to design a bandwidth allocation algorithm that calculates the slot allocation in two phases. The first phase decides the boundary of uplink and downlink sub-frames by satisfying requests with pending latency violation and proportionating according to traffic volume, while the second phase allocates slots to mobile stations considering urgency, priority and fairness. Simulation results show our algorithm achieves zero latency violation and higher system throughput compared to existing non-QoS/PHY-aware or less-QOS/PHY-aware approaches. (C) 2008 Elsevier B.V. All rights reserved.