Browsing by Author "Huang, Ching Yao"

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Analysis of an Adaptive P-Persistent MAC Scheme for WLAN Providing Delay Fairness
(2010-02-01)
Yen, Chih-Ming
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Chang, Chung-Ju
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Chen, Yih-Shen
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Huang, Ching Yao
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電機工程學系
The paper proposes and analyzes an adaptive p-persistent-based (APP) medium access control (MAC) scheme for IEEE 802.11 WLAN. The APP MAC scheme intends to support delay fairness for every station in each access, denoting small delay variance. It differentiates permission probabilities of transmission for stations which are incurred with various packet delays. This permission probability is designed as a function of the numbers of retransmissions and re-backoffs so that stations with larger packet delay are endowed with higher permission probability. Also, the scheme is analyzed by a Markov-chain analysis, where the collision probability, the system throughput, and the average delay are successfully obtained. Numerical results show that the proposed APP MAC scheme can attain lower mean delay and higher mean throughput. In the mean time. simulation results are given to justify the validity of the analysis, and also show that the APP MAC scheme can achieve more delay fairness than conventional algorithms.
Capacity-based compressed mode control method for inter-system handover in universal mobile telecommunication system
(2007-11-08)
Huang, Ching Yao
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Chang, Cheng Ta
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Ho, Chieh Yuan
The Inter-System handover is one of the key features in the third generation cellular systems. The compressed mode, with variable transmission gaps and power levels, is standardized to support the inter-frequency system handover. To minimize the use of system resources while maintaining the border-cell handover quality, a capacity-based compressed mode control method of the present invention is proposed. Considering the tradeoff between the capacity and the communication quality, the control method can adaptively manage the compressed mode operation based on the potential impacts on the capacity and the effectiveness of the compressed mode measurement. The present invention will improve the effectiveness and performance of the compressed mode operation.
Coloring-Based Inter-WBAN Scheduling for Mobile Wireless Body Area Networks
(2013-02-01)
Cheng, Shih Heng
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Huang, Ching Yao
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電子工程學系及電子研究所
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Department of Electronics Engineering and Institute of Electronics
In this study, random incomplete coloring (RIC) with low time-complexity and high spatial reuse is proposed to overcome in-between wireless-body-area-networks (WBAN) interference, which can cause serious throughput degradation and energy waste. Interference-avoidance scheduling of wireless networks can be modeled as a problem of graph coloring. For instance, high spatial-reuse scheduling for a dense sensor network is mapped to high spatial-reuse coloring; fast convergence scheduling for a mobile ad hoc network (MANET) is mapped to low time-complexity coloring. However, for a dense and mobile WBAN, inter-WBAN scheduling (IWS) should simultaneously satisfy both of the following requirements: 1) high spatial-reuse and 2) fast convergence, which are tradeoffs in conventional coloring. By relaxing the coloring rule, the proposed distributed coloring algorithm RIC avoids this tradeoff and satisfies both requirements. Simulation results verify that the proposed coloring algorithm effectively overcomes inter-WBAN interference and invariably supports higher system throughput in various mobile WBAN scenarios compared to conventional colorings.
Efficient Paging Control for Carrier Aggregation in LTE-A System
(2012-01-01)
Chou, Chie Ming
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Huang, Ching Yao
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電子工程學系及電子研究所
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Department of Electronics Engineering and Institute of Electronics
This paper studies paging operation when carrier aggregation (CA) is adopted in LTE-A system. A numerical analysis is provided and shows signaling overhead would increase significantly if paging is not properly controlled under CA. To overcome the problem, efficient paging controls are proposed while adaptive paging configurations on different component carrier are able to resist excessive overhead. In additional, a hierarchical paging message delivery scheme is jointly controlled to take paging latency into account. The results demonstrate that our proposal can work well in different environments with minimum changes in 3GPP specification.
Fuzzy Q-Learning Admission Control for WCDMA/WLAN Heterogeneous Networks with Multimedia Traffic
(2009-11-01)
Chen, Yung-Han
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Chang, Chung-Ju
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Huang, Ching Yao
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電子工程學系及電子研究所
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電信工程研究所
In this paper, admission control by a fuzzy Q-learning technique is proposed for WCDMA/WLAN heterogeneous networks with multimedia traffic. The fuzzy Q-learning admission control (FQAC) system is composed of a neural-fuzzy inference system (NFIS) admissibility estimator, an NFIS dwelling estimator, and a decision maker. The NFIS admissibility estimator takes essential system measures into account to judge how each reachable subnetwork can support the admission request's required QoS and then output admissibility costs. The NFIS dwelling estimator considers the Doppler shift and the power strength of the requested user to assess his/her dwell time duration in each reachable subnetwork and then output dwelling costs. Also, in order to minimize the expected maximal cost of the user's admission request, a minimax theorem is applied in the decision maker to determine the most suitable subnetwork for the user request or to reject. Simulation results show that FQAC can always maintain the system QoS requirement up to a traffic intensity of 1.1 because it can appropriately admit or reject the users' admission requests. Also, the FQAC can achieve lower blocking probabilities than conventional JSAC proposed in [20] and can significantly reduce the handoff rate by 15-20 percent.
Loading Prediction and Barring Controls for Machine Type Communication
(2013-01-01)
Chou, Chie Ming
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Huang, Ching Yao
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Chiu, Chun-Yuan
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電子工程學系及電子研究所
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Department of Electronics Engineering and Institute of Electronics
Machine Type Communication (MTC) is a very distinct technology that enables the "Internet of things". Overload that caused by a large number of MTC device is one of the primary issues for supporting MTC. Extended Access Barring (EAB) is a barring mechanism for long-term evolution (LTE) network to selectively control access attempts in order to prevent overload. In the paper, a method to predict access loading and adapt a barring ratio for EAB is designed. The simulation results show the proposal could relieve overload significantly without aggressively barring.
Multi-slope handoff algorithm for controlling dynamic communication quality in wireless communications
(2005-12-29)
Huang, Ching Yao
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Tsai, Ming Yuan
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Huang, Joe
A multi-slope handoff algorithm for controlling dynamic communication quality in wireless communications is proposed to let a mobile node adjust the handoff slope according to different communication connection situations for setting the optimum add/drop connection trigger thresholds. The algorithm comprises the following steps. First, a mobile node receives pilot strengths of its service pilot and nearby pilots to produce an aggregate strength. Next, the mobile node determines whether to perform handoff according to the magnitude of the aggregate strength. The handoff action is then controlled by multi-slope handoff operations to set an appropriate slope and to calculate the add/drop connection trigger thresholds when performing handoff. Finally, the pilot to be connected is selected based on the communication quality at that time. In this way, the quality of the communication service can be enhanced, the connection power consumption can be lowered, and the communication channel usage can be reduced.
Novel vertical handover control algorithm for WLAN and UMTS
(2007-04-26)
Huang, Ching Yao
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Chou, Chie Ming
In this invention, a novel vertical handover control algorithm, consisting of a throughput-based mapping function, QoS-based dynamic handover thresholds, and performance-based trigger timers, are proposed to resolve uncommon pilot problem, QoS requirements, and ping-pong effects, respectively. An analytic model based on a finite state machine is developed to evaluate the proposed algorithm in terms of the handover frequency and achievable throughput. A numerical analysis is also provided to further quantify the performance impacts.
Scheduling method for supporting quality of service (QoS) in wireless local area network (WLAN)
(2006-10-19)
Huang, Ching Yao
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Fan, Yu Long
A method for polling of stations in a Wireless Local Area Network (WLAN), comprising the steps of: obtaining Quality of Service (QoS) information related to the stations; assigning two timers to each WLAN service requiring QoS guarantee, one for uplink transmission and the other for downlink transmission; starting a Controlled Access Period (CAP) when a minimum timer Tm is below the threshold Tthr; polling the station with the minimum timer; updating the minimum timer after a polling message is sent; quitting CAP and permitting the resource contention if the minimum timer Tm is larger than the threshold Tthr.
Two-tier call admission control algorithm in IEEE 802.11 WLAN
(2008-03-27)
Huang, Ching Yao
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Shih, Yuan Hwai
The present invention discloses a two-tier call admission control algorithm in IEEE 802.11 WLAN. The two-tier call admission control algorithm is given to improve the overall system throughput and guarantee the quality of service of every single user in the WLAN.