Browsing by Author "Kuo, Yaw-Wen"

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A Data Mapping Algorithm for Two-Level Requests in WiMAX Systems
(2012)
Lee, Tsern-Huei
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Liu, Chi-Hsien
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Campbell, Arleth Soleiy Garth
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Kuo, Yaw-Wen
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傳播研究所
The IEEE 802.16e standard known as Mobile WiMAX has recently been introduced. It is considered as one of the most promising wireless access technologies supporting high data throughput with low cost of deployment. Mobile WiMAX makes use of Orthogonal Frequency-Division Multiple Access (OFDMA) digital modulation scheme as the transmission method. With the constraint requires that all requests have to be mapped as a rectangle, it is shown that finding an optimum mapping solution is an NP-complete problem. Many burst mapping algorithms have been proposed, but none considered the case with prioritized requests. This paper presents an efficient packing algorithm for two-level requests with two targets: (1) map high (MUST part) priority data as much as possible; and (2) achieve high efficiency, reduces the number of unused slots, and minimizes the mapping information overhead. Simulation results show that the proposed algorithm achieves high efficiency.
A Downlink Mapping Algorithm for Two-Level Requests in IEEE 802.16e Systems under AMC Mode
(2013)
Yang, Zi-Yang
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Kuo, Yaw-Wen
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Lee, Tsern-Huei
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傳播研究所
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Institute of Communication Studies
This paper proposes a downlink mapping algorithm for two-level requests in Orthogonal Frequency Division Multiple Access based IEEE 802.16e systems under the Adaptive Modulation and Coding (AMC) mode by which the modulation and coding scheme (MCS) of a user may be different for available subchannels. Given a set of requests each with two priorities, the proposed algorithm efficiently allocates a two-dimensional (time and frequency) burst with a suitable MCS to each user to maximize the system throughput with service differentiation. Simulation results show that the proposed algorithm outperforms the Efficient Downlink Mapping Allocation (EDMA) algorithm [5] in terms of the throughput of high priority data, but slightly sacrifice in overall throughput. The proposed algorithm can improve up to 98.8% more the average allocated ratio of urgent data than the EDMA.
An analysis of channel utilization for the IEEE 802.11 with aggregation
(2006)
Sung, Cheng-Chia
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Kuo, Yaw-Wen
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Lee, Tsern-Huei
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電信工程研究所
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Institute of Communications Engineering
The IEEE 802.11 MAC provides a method for multiple users to share the wireless media. The channel utilization is limited because of protocol overhead no matter how fast the payload is transmitted. To increase utilization, frame aggregation is a straightforward way to improve the channel efficiency. This paper presents an analytic method to estimate the utilization for RTS/CTS-based contention access mechanism with unidirectional or bidirectional aggregation. Simulation results are also provided to show the accuracy of the analytic model.
An Efficient Downlink Mapping Algorithm for AMC Mode in WiMAX Systems
(2012)
Lee, Tsern-Huei
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Yang, Zi-Yang
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Huang, Qi-Quan
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Kuo, Yaw-Wen
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傳播研究所
This paper proposes an efficient downlink resource allocation scheme for Orthogonal Frequency Division Multiple Access based WiMAX systems using the Adaptive Modulation and Coding mode operation. Given a set of user requests, the proposed algorithm determines the modulation scheme and allocates a two-dimensional (time and frequency) burst to each user. It is known that finding the optimal solution for such a resource allocation problem is NP-complete. To reduce the computation complexity, this paper proposes a heuristic solution. Compared with the Efficient Downlink Bandwidth Allocation (EDBA) algorithm [6], the proposed scheme achieves higher channel utilization and system throughput with similar execution time. Simulation results show that the average channel utilization of the proposed scheme is about 75 similar to 85% and that of EDBA is about 60 similar to 70%.
An Enhanced Data Mapping Algorithm for Two-Level Requests in WiMAX Systems
(2013)
Lee, Tsern-Huei
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Le, Dinh-Dung
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Kuo, Yaw-Wen
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傳播研究所
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Institute of Communication Studies
The IEEE 802.16e standard, which adopts OFDMA PHY and is generally known as Mobile WiMAX, has grabbed the attention of wireless communication industry for the past few years. It is a technology optimized for IP-based high speed long-distance wireless broadband access. In the downlink of Mobile WiMAX systems, data requests have to be mapped into rectangular regions. Such a constraint results in an NP-complete problem in order to maximize throughput. Several heuristic data mapping algorithms were proposed trying to achieve high system throughput. Most of the algorithms handle only one type of data. In a previous paper, we presented a data mapping algorithm which maps two levels of requests, i.e., urgent and non-urgent data. However, only the numbers of required slots were considered in determining the order of data mapping. In this paper, we propose an enhanced version which considers both the number of required slots and the Modulation and Coding Scheme (MCS) for each mobile station. Simulation results show that, compared with previous design, the enhanced algorithm serves more urgent data with higher throughput.
Design and Evaluation of a High Throughput MAC with QoS Guarantee for Wireless LANs
(2009)
Kuo, Yaw-Wen
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Lee, Tsern-Huei
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Huang, Yu-Wen
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Hsieh, Jing-Rong
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電信工程研究所
The IEEE 802.11e and the IEEE 802.11n focus on quality of service (QoS) and enhancements for high throughput respectively. Modern wireless LAN (WLAN) products should integrate both features. This paper presents a design of a high throughput MAC with QoS guarantee which combines the Hybrid Coordination Function (HCF) of the 802.11e with the frame aggregation technique in the 802.11n. The basic idea of the design is to improve the throughput of best-effort traffic under the constraint that QoS is just met for real-time traffic. Simulation results show that the proposed MAC has high channel utilization and the delay of best-effort traffic is also reduced.
Efficient resource allocation algorithm for overlay D2D communication
(2017-09-04)
Yang, Zi-Yang
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Kuo, Yaw-Wen
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電信工程研究所
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Institute of Communications Engineering
Device-to-device (D2D) communication in cellular systems offers an economically viable means of improving the system capacity by allocating multiple D2D links within the same resource block (RB), under appropriate interference-control techniques. In this paper, we propose an efficient resource allocation algorithm that enables maximum spatial reuse in orthogonal frequency division multiple access (OFDMA) systems. Given a set of D2D requests, the proposed algorithm greedily determines the number of RBs required, following the reliability criteria. Simulation results show that, compared to the greedy algorithm (Lee, Choi, and Jeon, 2013), the proposed algorithm could save up to 18.6% RBs, improve the throughput per RB by up to 23.4%, and reduce the computation time by up to 67.9%. (C) 2017 Elsevier B.V. All rights reserved.
Energy-Efficient Multi-Polling Scheme for Wireless LANs
(2009-03-01)
Hsieh, Jing-Rong
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Lee, Tsern-Huei
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Kuo, Yaw-Wen
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電信工程研究所
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Institute of Communications Engineering
In the past few years, IEEE 802.11 wireless LANs (WLANs) has rapidly gained large popularity for broadband wireless access. With the growing of various applications, users are demanding features such as higher throughput white keeping respectable operation time for their devices. To provide higher system bandwidth utilization, multi-polling mechanisms are often employed to reduce protocol overhead. However, they require wireless stations (STAs) to spend much time in overhearing which tends to waste energy and reduce battery lifetime. In this paper, we propose an energy-efficient multi-polling mechanism which combines power management strategy with a low overhead Medium Access Control (MAC) protocol. The main idea is to put STAs into the Doze state and determine a suitable wake-up time schedule to statistically achieve desirable guarantee of bandwidth utilization. From both analysis and simulation results, we found that, compared with the original ordered-contention multi-polling scheme, our proposed mechanism saves up to 80% of energy for a network consisting of 20 polled STAs with 5% loss of system bandwidth utilization as tradeoff. The significant saving of energy is a consequence of alleviating the overhearing problem with well scheduled wake-up times for STAs.
Maximum Rectangle-Based Down-Link Burst Allocation Algorithm for WiMAX Systems
(2011)
Lee, Tsern-Huei
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Liu, Chi-Hsien
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Yau, Jimmy
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Kuo, Yaw-Wen
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傳播研究所
The IEEE 802.16e standard known as Mobile WiMAX has recently been introduced. Because of the high data throughput and low cost of deployment, it becomes one of the leading solutions for wireless broadband services. Mobile WiMAX makes use of Orthogonal Frequency-Division Multiple Access (OFDMA) digital modulation scheme as the transmission method. The standard specifies that a data burst in the downlink subframe needs to be mapped into a time and frequency domain with a rectangular shape, but how the data bursts are organized to minimize the wasted space is not detailed. Many burst mapping algorithms have been proposed by researchers in these late years. This paper presents an efficient packing algorithm which achieves high throughput, reduces the number of unused slots, and minimizes the mapping information overhead. We compare the performance of our proposed algorithm with that of eOCSA, a high-performance packing algorithm recently presented by other researchers. Simulation results show that our proposed algorithm outperforms eOCSA.
Power efficient multipolling mechanism for next generation wireless LANs
(2007)
Hsieh, Jing-Rong
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Lee, Tsern-Huei
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Kuo, Yaw-Wen
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電信工程研究所
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Institute of Communications Engineering
As the Wireless LAN (WLAN) becomes prevalent, users are demanding more and more features such as high throughput and low power consumption. To provide higher channel efficiency, contention-based multipolling mechanism was proposed to improve the single polling and contention-free multipolling mechanisms. However, when this medium access control (MAC) protocol is used, wireless stations would need to spend much time in overhearing which tends to waste energy and reduce battery lifetime. We propose a power efficient multipolling mechanism to arrange wireless stations into groups and put them into sleep mode when other stations are transmitting. From the simulation results, we find the proposed mechanism can address the issue of overhearing while also keeping the flexibility and high channel efficiency properties.
To Piggyback Or Not to Piggyback Acknowledgments?
(2010)
Lee, Tsern-Huei
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Kuo, Yaw-Wen
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Huang, Yu-Wen
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Liu, Yung-Hsiang
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電信工程研究所
Piggyback is an effective way to reduce the MAC protocol overhead of wireless networks. This paper considers the physical data rate and transmission bit error to derive the criterion of piggyback. Numerical results show that the improvement of piggyback can reach 40% for some cases. For given the bit error rate and the data rate, we also provide the criterion for every combination in a table.