Browsing by Author "Chen, A"

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Microarray analysis of ovarian cancer
(2005)
Huang, GS
;
Hung, YC
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Chen, A
;
Hong, MY
;
材料科學與工程學系奈米科技碩博班
Microarray experiments were performed to normal ovaries, benign ovarian tumor and stage I and III of ovarian cancer. By treating benign ovarian tumor as pre-cancerous stage and comparing to later stages of ovarian cancer we identified 46 genes overly expressed in early-staged cancer. We also identified over-expressed genes at all stages of ovarian tumor/cancer. The over-expressed genes might be alternative candidates for developing early diagnostic markers. JUN and nuclear receptor subfamily genes were repeatedly identified in the group of down-regulated genes indicating their important regulatory roles in the oncogenesis of ovary.
NICE - A decentralized medium access control using neighborhood information classification and estimation for multimedia applications in ad hoc 802.11 wireless LANs
(2003)
Chen, A
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Wang, LC
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Su, Y
;
Zheng, YX
;
Yang, B
The desired properties of a medium access control (MAC) protocol in mobile ad hoc network (MANET) include (1) meet quality of service (QoS) requirements for real-time nodes, (2) be decentralized, (3) achieve fairness from viewpoint of throughput or energy consumption, and (4) be immune to the hidden node problem. Though there have been numerous proposed MAC protocols for the IEEE 802.11 WLAN, few of them possesses all of the above four properties. In this paper, we propose a new MAC scheme satisfying all of above four properties. Our protocol can support real-time traffic and satisfy QoS requirements, and can achieve fairness among non-real-time nodes. Also, without using any centralized control, it can be easily deployed in MANET. An analytic model of the protocol's throughput has also been developed. We compare the protocol's throughput obtained from its analytic model and simulation to validate each other.
On the throughput performance of CSMA-based wireless local area network with directional antennas and capture effect: A cross-layer analytical approach
(2004)
Wang, LC
;
Huang, SY
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Chen, A
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電信工程研究所
;
Institute of Communications Engineering
In this paper we develop a cross-layer analytical approach front both the physical layer and the medium access control (MAC) layer to evaluate the performance of the IEEE 802.11 wireless local area network (WLAN). Front the physical layer, this analytical approach incorporates the effects of both capture and directional antenna, while front the MAC layer, our model takes account of the carrier sense multiple access with collision avoidance (CSMA/CA) protocol. Through a cross-layer modeling technique, this analytical framework can provide valuable insights of the physical layer impact on the throughput performance of the CSMA/CA MAC protocol. These insights can he helpful in developing a NLAC protocol to fully take advantage of directional antennas for enhancing the performance of the WLAN.
QoS contention control for optical coarse packet switched IP-over-WDM network
(2005)
Yuang, MC
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Tien, PL
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Shih, J
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Lee, SSW
;
Lin, YM
In this paper, we first introduce an Optical Coarse Packet Switching (OCPS) paradigm. In principle, OCPS advocates the enforcement of traffic engineering and control to realize bandwidth-on-demand on sub-wavelength basis while circumventing optical packet switching limitations. Based on OCPS, we have constructed an experimental optical IP-over-WDM network testbed, referred to as OPSINET. In the paper, we present the architectural design of OPSINET and its Hybrid Contention Control (HCC) mechanism aiming to satisfy various classes of loss QoS guarantees. The mechanism preventively adopts appropriate burst sizes for different traffic classes during packet burstification at ingress routers. It also reactively performs prioritized contention resolution at OLSRs in the presence of contention. Experimental results show that HCC invariantly achieves low loss probability as a result of burstification-based traffic shaping. Moreover, it provides satisfied loss guarantees for high-priority classes while incurring minimal loss degradation for lower-priority classes.
QoS Scheduler/Shaper for optical coarse packet switching IP-over-WDM networks
(2004-11-01)
Yuang, MC
;
Tien, PL
;
Shih, J
;
Chen, A
;
資訊工程學系
For IP-over-WDM networks, optical coarse packet switching (OCPS) has been proposed to circumvent optical packet switching limitations by using in-band-controlled per-burst switching and advocating traffic control enforcement to achieve high bandwidth utilization and quality-of-service (QoS). In this paper, we first introduce the OCPS paradigm. Significantly, we present a QoS-enhanced traffic control scheme exerted during packet aggregation at ingress nodes, aiming at providing delay and loss class differentiations for OCPS networks. Serving a dual purpose, the scheme is called (psi, tau)-Scheduler/Shaper, where psi and tau are the maximum burst size and burst assembly time, respectively. To provide delay class differentiation, for IP packet flows designated with delay-associated weights, (psi, tau)-Scheduler performs packet scheduling and assembly into bursts based on their weights and a virtual window of size psi. The guaranteed delay bound for each delay class is quantified via the formal specification of a stepwise service curve. To provide loss class differentiation, (psi, tau)-Shaper facilitates traffic shaping with larger burst sizes assigned to higher loss priority classes. To examine the shaping effect on loss performance, we analytically derive the departure process of (psi, tau)-Shaper. The aggregate packet arrivals are modeled as a two-state Markov modulated Bernoulli process (MMBP) with batch arrivals. Analytical results delineate that (psi, tau)-Shaper yields substantial reduction, proportional to the burst size, in the coefficient of variation of the burst interdeparture time. Furthermore, we conduct extensive simulations on a 24-node ARPANET network to draw packet loss comparisons between OCPS and just-enough-time (JET)-based OBS. Simulation results demonstrate that, through burst size adjustment, (psi, tau)-Shaper effectively achieves differentiation of loss classes. Essentially, compared to JET-based OBS using out-of-band control and offset-time-based QoS strategy, OCPS is shown to achieve invariably superior packet loss probability for a high-priority class, facilitating better differentiation of loss traffic classes.
Stochastic modeling and real-time prediction of incident effects on surface street traffic congestion
(2004-05-01)
Sheu, JB
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Chou, YH
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Chen, A
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運輸與物流管理系註：原交通所+運管所
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Department of Transportation and Logistics Management
Modeling and real-time prediction of incident-induced time-varying lane traffic states, e.g., mandatory lane-changing fractions, queue lengths, and delays are vital to investigate the time-varying incident effects on traffic congestion in both the spatial and temporal domains. This paper presents a discrete-time nonlinear stochastic model to characterize the time-varying relationships of specified lane traffic states under the condition of lane-blocking incidents on surface streets. The proposed stochasti: model is composed of four types of equations: (1) recursive equations, (2) measurement equations, (3) delay-aggregation equations, and (4) boundary constraints. In addition, a recursive estimation algorithm is developed for real-time prediction of the specified time-varying lane traffic states. The proposed method Is tested with simulated data generated using the Paramics traffic simulator. The preliminary tests indicate the capability of the proposed method to estimate incident effects on surface street traffic congestion in real time. We also expect that this study can provide real-time incident-related traffic information with benefits both for understanding the impact of incidents on non-recurrent traffic congestion of surface streets, and for developing advanced incident-responsive traffic control and management technologies. (C) 2003 Elsevier Inc. All rights reserved.