Browsing by Author "Lin, YD"

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A hierarchical network storage architecture for video-on-demand services
(1997-06-01)
Lai, YC
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Lin, YD
;
Lai, HZ
;
交大名義發表
;
資訊工程學系
Recent advances in Cable TV networks and multimedia technologies open the possibilities for network/service/content providers to offer residential customers with video-on-demand services. However, the mass storage system in supporting such services demands proper organization and management. In this paper we present a three-level hierarchical network storage architecture for the video-on-demand storage system. At the first-level (Local Service Center, LSC) a limited number of programs with high viewing probabilities are stored; while at the second-level (Local Central Service Center, LCSC) a few programs with second high viewing probabilities are stored. The third-level (Central Service Center, CSC) contains all programs provided in the system. Based on this architecture and the program viewing probability distribution function, we use a minimum-cost function to find out the numbers of programs stored in the two service centers (LSC and LCSC) and numbers of links among these three service centers. We also describe two program reallocation algorithms which swap programs between service centers according To the change in user request patterns.
A hierarchical network storage architecture for video-on-demand services
(1996)
Lin, YD
;
Lai, HZ
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Lai, YC
;
資訊工程學系
;
Department of Computer Science
A K-band aperture-coupled microstrip leaky-wave antenna
(1999-07-01)
Chen, TL
;
Lin, YD
;
傳播研究所
;
Institute of Communication Studies
Microstrip leaky-wave antenna fed bf an aperture-coupled microstrip operating at K-band is presented. Using the aperture-coupled microstrip as a feeding structure can fully exploit the wideband characteristic of the microstrip leaky-wave antenna. The dimensions of the antenna are obtained from the calculation of the propagation characteristics. Measurement shows a bandwidth of 22% for VSWR < 2 : 1 and a peak power gain of 12 dBi at 22 GHz for one element. Four-element array is developed with a gain of 18.7 dBi and the frequency-scanning feature is exhibited. The waveguide model is verified by measuring the 3-D, radiation pattern of the microstrip leaky-wave array.
A novel pairing algorithm for high-speed large-scale switches
(2000-01-01)
Wu, JSC
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Lin, YD
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資訊工程學系
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Department of Computer Science
Motivated by the observation that switch throughput is mainly limited by the number of the maximum matching or pairing, instead of the head-of-line (HOL) effect, a pairing algorithm trying to maximize the number of pairing, for switches with K buffers in each input port is proposed. As shown in the related formula and simulation data, this algorithm performs well and can boost the switch throughput to 0.981 from traditional 0.632 when K = 4 even as the switch size --> infinity.
A parallel automaton string matching with pre-hashing and root-indexing techniques for content filtering coprocessor
(2005)
Tseng, KK
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Lin, YD
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Lee, TH
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Lai, YC
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交大名義發表
We propose a new Parallel Automaton string matching approach and its hardware architecture for content filtering coprocessor. This new approach can improve the average matching time of the Parallel Automaton with Pre-Hashing and Root-Indexing techniques. The Pre-Hashing technique uses a hashing function to verify quickly the text against the partial patterns in the Automaton, and the Root-Indexing technique matches multiple bytes for the root state in one single matching. A popular Automaton algorithm, Aho-Corasick (AC) is chosen to be implemented by adding the two techniques; we employ these two techniques in a memory efficient version of AC namely Bilmap AC For the average-case time, our approach improves Bitmap AC by 494% and 224% speedup for URL and Virus patterns, respectively. Since Pre-Hashing and Root-Indexing techniques can be concurrently executed with Bitmap AC in the hardware, our proposed approach has the same worst-case time as Bitmap AC.
A timestamp-sensitive scheduling algorithm for MPEG-II multiplexers in CATV networks
(1998-09-01)
Lin, YD
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Liu, CM
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資訊工程學系
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Department of Computer Science
To achieve smooth display of MPEG-II programs in the residential cable TV networks, we present a timestamp-sensitive scheduling algorithm for MPEG-II multiplexers. The deadline-driven scheduler maintains, for each program stream, a counter and a timestamp to record and determine how many Transport Stream (TS) packets should be transmitted before the current scheduling cycle ends. The decoding timestamp (DTS) of TS packets is used to update the counter in order to prevent deadline violation. This algorithm is compared numerically with the timestamp-insensitive algorithm which runs constant-bit-rate (CBR) scheduling. The trace-driven simulation shows that the deadline violation of our timestamp-sensitive scheduling is much lower than CBR's and well controlled for programs with various degrees of burstiness. We also show that the algorithm can be further improved by adding a scheme to prevent buffer underflow and overflow at multiplexers and set-top-boxes, respectively.
Alarm correlation for congestion diagnosis in ATM networks
(1996)
Lin, YD
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Yang, RK
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Lo, CC
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資訊工程學系
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Department of Computer Science
Allocation and scheduling algorithms for IEEE 802.14 and MCNS in hybrid fiber coaxial networks
(1998-12-01)
Lin, YD
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Huang, CY
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Yin, WM
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資訊工程學系
;
Department of Computer Science
IEEE 802.14 and MCNS are two standards developed for the Hybrid Fiber Coaxial (HFC) CATV networks. Both standards model an upstream channel as a stream of minislots. But their philosophies on resolving collisions in the shared upstream channel are rather different, where IEEE 802.14 adopts the priority+FIFO first-transmission rule and the n-ary tree retransmission rule, and MCNS adopts the binary exponential backoff algorithm with adjustable window sizes. Both provide reservation access, while IEEE 802.14 and MCNS also support isochronous aceess and immediate access, respectively. In this paper, we try to prepare a suggestion list for vendors on how to allocate minislots for reservation aceess and immediate access and how to schedule the reserved bandwidth, which greatly affect the performance of a cable network and are left open by the standards.
Allocation and scheduling algorithms for IEEE 802.14 and MCNS in hybrid fiber coaxial networks
(1998-12-01)
Lin, YD
;
Huang, CY
;
Yin, WM
;
資訊工程學系
;
Department of Computer Science
IEEE 802.14 and MCNS are two standards developed for the Hybrid Fiber Coaxial (HFC) CATV networks. Both standards model an upstream channel as a stream of minislots. But their philosophies on resolving collisions in the shared upstream channel are rather different, where IEEE 802.14 adopts the priority+FIFO first-transmission rule and the n-ary tree retransmission rule, and MCNS adopts the binary exponential backoff algorithm with adjustable window sizes. Both provide reservation access, while IEEE 802.14 and MCNS also support isochronous aceess and immediate access, respectively. In this paper, we try to prepare a suggestion list for vendors on how to allocate minislots for reservation aceess and immediate access and how to schedule the reserved bandwidth, which greatly affect the performance of a cable network and are left open by the standards.
An efficient and orderly implementation of bypass queue under bursty traffic
(1998-12-01)
Wu, JSC
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Lin, YD
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資訊工程學系
;
Department of Computer Science
Sharma and Pinnu proposed an implementation of bypass queue by many FIFOs; unfortunately, the detailed procedure paid little attention to maintaining cell sequence, which is an important feature in ATM network. In this paper, we propose an improved architecture which guarantees cell sequence integrity and describe its related operating procedures. (C) 1998 Elsevier Science B.V. All rights reserved.
An improved dynamic model in integral equation methods for the characterization of discontinuities in planar circuits
(1996-07-01)
Sheen, JW
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Lin, YD
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電信工程研究所
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Institute of Communications Engineering
An efficient method to improve the integral equations method is presented in this article. A delta gap source generator and the fundamental mode sampling technique are employed. By employing this modified method, observation of the SWR and the creation of a large matrix in the conventional method employing a delta gap source generator are not necessary. Also, the modeling complexity and the time-consuming computation of the conventional method, which employs the semiinfinite traveling-wave mode, are avoided. In this article we use the coplanar waveguide short-end discontinuity as an example to describe this method in the spectral domain. Moreover, numerical results are compared with our experimental data and they show good agreement. (C) 1996 John Wiley & Sons, Inc.
An improved dynamic model in integral equation methods for the characterization of discontinuities in planar circuits
(1996-07-01)
Sheen, JW
;
Lin, YD
;
交大名義發表
;
傳播研究所
;
National Chiao Tung University
An efficient method to improve the integral equations method is presented in this article. A delta gap source generator and the fundamental mode sampling technique are employed. By employing this modified method, observation of the SWR and the creation of a large matrix in the conventional method employing a delta gap source generator are not necessary. Also, the modeling complexity and the time-consuming computation of the conventional method, which employs the semiinfinite traveling-wave mode, are avoided. In this article we use the coplanar waveguide short-end discontinuity as an example to describe this method in the spectral domain. Moreover, numerical results are compared with our experimental data and they show good agreement. (C) 1996 John Wiley & Sons, Inc.
Analysis and design of broadside-coupled striplines-fed bow-tie antennas
(1998-03-01)
Lin, YD
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Tsai, SN
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傳播研究所
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Institute of Communication Studies
The design of a bow-tie antenna fed by broadside-coupled striplines (BCS) for the 2.4-GHz ISM band is described in this letter. The two fins of the bow tie are, respectively, on the two sides of the substrate. The feeding balanced lines adopted are the BCS. A quarter-wave transformer Is used to transform the microtrip line input to the BCS feed. Analysis method based on the mixed-potential integral equation method is used to characterize the input characteristics of the bow-tie antenna. Obtained numerical results are in good agreement with experimental data. Through experiments with bow-tie antennas of various extended angles, the bow-tie antenna with a 90 degrees extended angle exhibits the widest bandwidth in the desired frequency band, which has a bandwidth of 19% for VSWR < 1.5:1.
Analysis and design of feeding structures for microstrip leaky wave antenna
(1996-09-01)
Lin, YD
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Sheen, JW
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Tzuang, CKC
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交大名義發表
;
傳播研究所
Three arrangements of the feeding structure for the excitation of a microstrip leaky wave antenna are proposed and investigated in this paper, A full-wave spectral domain integral equation method combined with the fundamental mode sampling technique is applied to determine the reflection coefficient of the excitation source. Tabulation technique is used to reduce the computational effort. Dependence on structural parameters such as line width, line spacing and overlap length is fully analyzed to obtain the design criteria for a microstrip leaky wave antenna. Additionally, an experimental setup is used to check the validity of our numerical results and verify the radiation nature of the microstrip line first higher-order mode.
Analytical solutions of the azimuthal deviation of a polarizer and an analyzer by polarizer-sample-analyzer ellipsometry
(2006-06-10)
Chao, YF
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Lee, KY
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Lin, YD
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光電工程學系
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Department of Photonics
The analytical solutions of the azimuthal deviation of a polarizer and an analyzer were obtained by polarizer-sample-analyzer ellipsometry with a three-intensity measurement technique. By performing two sets of this three-intensity measurement with the polarizer's azimuth set at 45 degrees and at -45 degrees, we were able to obtain a set of ellipsometric parameters free from the azimuthal deviations of the polarizer and the analyzer. (c) 2006 Optical Society of America.
Aperture-coupled microstrip line leaky wave antenna with broadside mainbeam
(1998-07-09)
Chen, TL
;
Lin, YD
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傳播研究所
;
Institute of Communication Studies
A microstrip first higher order leaky wave antenna (LWA), centre-fed by an aperture-coupled microstrip with a broadside mainbeam, is presented. The measured bandwidth (23% for VSWR < 2:1) is in agreement with the leaky radiation band predicted. The experimental gain patterns, compared with those of a patch antenna fed by the same type of structure, reveal the difference between these two kinds of antenna. With increasing frequency, the radiation field of the LWA spreads into the H-plane, forming a flatter broadside pattern, which can be applied to long rectangular area communication.
Assessing and improving TCP rate shaping over edge gateways
(2004-03-01)
Wei, HY
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Tsao, SC
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Lin, YD
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資訊工程學系
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Department of Computer Science
Computers installed with commercial/open-source software have been widely employed as organizational edge gateways to provide policy-based network management. Such gateways include firewalls for access control, and bandwidth managers for managing the narrow Internet access links. When managing the TCP traffic, pass-through TCP flows can introduce large buffer requirements, large latency, frequent buffer overflows, and unfairness among flows competing for the same queue. So, how to allocate the bandwidth for a TCP flow without the above drawbacks becomes an important issue. This study assesses and improves TCP rate shaping algorithms to solve the above problems through self-developed implementations in Linux, testbed emulations, live Internet measurements, computer simulations, modeling, and analysis. The widely deployed TCP Rate control (TCR) approach is found to be more vulnerable to Internet packet losses and less compatible to some TCP sending operating systems. The proposed PostACK approach can preserve TCR's advantages while avoiding TCR's drawbacks. PostACK emulates per-flow queuing, but relocates the queuing of data to the queuing of ACKs in the reverse direction, hence minimizing the buffer requirement up to 96 percent. PostACK also has 10 percent goodput improvement against TCR under lossy WAN environments. A further scalable design of PostACK can scale up to 750Mbps while seamlessly cooperating with the link-sharing architecture. Experimental results can be reproduced through our open sources: 1) tcp-masq: a modified Linux kernel, 2) wan-emu: a testbed for conducting switched LAN-to-WAN or WAN-to-LAN experiments with RTT/loss/jitter emulations.
Bandwidth brokers of instantaneous and Book-ahead requests for Differentiated Services networks
(2001)
Lin, YD
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Chang, CH
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Hsu, YC
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資訊工程學系
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Department of Computer Science
The Quality of Service (QoS) reservations in Differentiated Service (DiffServ) networks can be classified into two sets; Book-ahead (BA) requests and Instantaneous Requests (IRs). When an admitted BA request becomes active, some ongoing IRs are dropped when the bandwidth is insufficient for supporting both IRs and BA requests. The admission control should predict the lifetime, i.e. look-ahead time, of the IRs to prevent the admitted IRs from being dropped. The control should then check whether the available bandwidth during the look-ahead time is sufficient for the incoming IRs. We propose an application-aware look-ahead admission control for IRs, which determines the look-ahead time for specific types of IR applications. An admitted BA request might block subsequent ones that could bring more effective revenue. Thus, we propose the deferrable model of the admission control for BA requests. Simulation results indicate that the application-aware look-ahead admission control successfully reduces the dropping probability and wasted revenue of IRs by up to 10 times and 30%, respectively. Besides, the deferrable model indeed results in more BA effective revenue.
Bandwidth brokers of instantaneous and book-ahead requests for differentiated services networks
(2002-01-01)
Lin, YD
;
Chang, CH
;
Hsu, YC
;
資訊工程學系
;
Department of Computer Science
The Quality of Service (QoS) reservations in Differentiated Service (DiffServ) networks can be classified into two sets: Book-ahead (BA) requests and Instantaneous Requests (IRs). When an admitted BA request becomes active, some ongoing IRs is dropped when the bandwidth is insufficient for supporting both IRs and BA requests. The admission control should predict the lifetime, i.e. look-ahead time, of the IRs to prevent the admitted IRs from being dropped, The control should then check whether the available bandwidth during the look-ahead time is sufficient for the incoming IRs. We propose an application-aware look-ahead admission control for IRs, which determines the lookahead time for specific types of IR applications. An admitted BA request might block subsequent ones that could bring more effective revenue. Thus, we propose the deferrable model of the admission control for BA requests, Simulation results indicate that the application-aware look-ahead admission control successfully reduces the dropping probability and wasted revenue of IRs by up to 10 times and 30%, respectively. Besides, the deferrable model indeed results in more BA effective revenue.
Base-centric routing protocol for multihop cellular networks
(2002)
Hsu, YC
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Lin, YD
;
資訊工程學系
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Department of Computer Science
This paper presents base-centric routing (BCR) protocol, which is designed for Multihop Cellular Networks (MCNs) for wireless data communications. MCN, in which packets are multi-hopped to their destination, is hybrid of traditional Singlehop Cellular Networks (SCNs) and ad-hoe networks architecture. Because the existing routing protocols designed for ad-hoc networks are not suitable for MCN, herein, a hybrid of table-driven and demand-driven protocols with base-centric computing is designed. The base tracks network topology by the table-driven method and can thus compute paths for MSs, constituting base-centric computing. When paths are needed by MSs, when is demand-driven, the path query messages are unicast to the base. If MSs do not obtain paths from the base, then path query messages will be flooded as in AODV. Simulation yields the following conclusions. The throughput of MCN increases as radio distance decreases and is higher than that of SCN. When the radio distance in MCN is the same as that in SCN, the throughput in MCN is about twice that in SCN. Moreover, the improvement can be by up to a factor of three when the radio distance in MCN is 1/4 of that in SCN. The hybrid protocol outperforms AODV because with base-centric computing, path query messages can be unicast to the base and the overhead is greatly reduced. Without mobility, UDP outperforms TCR However, with mobility, TCP outperforms UDP.