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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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The Journal of Korean Institute of Communications and Information Sciences
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Volume 25, Issue 12B - Dec 2000
Volume 25, Issue 12A - Dec 2000
Volume 25, Issue 11B - Nov 2000
Volume 25, Issue 11A - Nov 2000
Volume 25, Issue 10B - Oct 2000
Volume 25, Issue 10A - Oct 2000
Volume 25, Issue 9B - Sep 2000
Volume 25, Issue 9A - Sep 2000
Volume 25, Issue 8B - Aug 2000
Volume 25, Issue 8A - Aug 2000
Volume 25, Issue 7B - Jul 2000
Volume 25, Issue 7A - Jul 2000
Volume 25, Issue 6B - Jun 2000
Volume 25, Issue 6A - Jun 2000
Volume 25, Issue 5B - May 2000
Volume 25, Issue 5A - May 2000
Volume 25, Issue 4B - Apr 2000
Volume 25, Issue 4A - Apr 2000
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Volume 25, Issue 1B - Jan 2000
Volume 25, Issue 1A - Jan 2000
Volume 25, Issue 9 - 00 2000
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Volume 25, Issue 7 - 00 2000
Volume 25, Issue 5 - 00 2000
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Design and Performance Analysis of CDMA Radio Link Protocols for QoS Control of Multimedia Traffic
조정호 ; 이형옥 ; 한승완 ;
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 4, 2000, Pages 451~451
In this paper, we design the radio data link protocols with Qos provisioning for mobile multimedia such as voice, data, and video in CDMA-based ATM networks, and analyze the performance of the data link protocols. To support mobile multimedia traffic, the required QoS parameters and the characteristics are analyzed, and wireless protocol stacks are proposed for integrating the wireless access network and ATM transport networks, and radio data link protocols are designed for provisioning QoS Control. The data link protocols are analyzed assuming that the system is supporting voice and data traffic simultaneously. In case of data traffic, the delay and throughput of SREJ ARQ and Type-1 Hybrid ARQ scheme are compared, and in case of voice traffic, the packet loss rate of BCH coding is analyzed according to the varying data traffic loads. The results indicate that the adaptive radio link protocols are efficient to support Qos requirements while the complexities are increased.
Analysis of Parallel Interference Cancellation with the Improved Initial Stage
염순진 ; 박용완 ;
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 4, 2000, Pages 464~464
In this paper, we introduce a modified interference cancellation scheme to overcome MAI(Multiple Access Interference) in DS-CDMA. Among ICs(Interference Canceller), PIC(Parallel Interference Canceller) requires the more stages to have the better BER(Bit Error Rate), and SIC(Successive Interference Canceller) faces the problems of power reordering and large delays. To resolve the problems of them, we propose a modified interference cancellation scheme combining SIC and PIC. The proposed interference canceller has improved the performance through the total received signal applied sorting method is fed into the initial stage. Its structure extracts the good characteristics because of the input signal removed MAI in the initial stage. The characteristics of the proposed system are as follows; (1) smaller delay, and the strongest user signal is also reduced to MAI (unlike SIC), (2) it has the good BER performance only using fewer stages (unlike PIC).
English Channel Allocation Scheme based on Multiple Guard Channels
박희철 ; 이도형 ; 박영근 ;
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 4, 2000, Pages 471~471
With the limited wireless resources, various traffic in the cellular system is served based on micro-cell or pico-cell structure. The rapid increase in the number of mobile users results in the frequent handoff which is becoming a critical issue. In this paper, we propose a channel allocation scheme to reduce the probability of handoff failure. In this scheme, we provide a guard channel for each service to handle the handoff processes. It maintains the low probability of failure in handoff calls. To prevent the performance degradation due to the traffic variation, we use a channel arbitration method that adaptively manages the number of channels based on the call density. We evaluated the performance in terms of the initial call blocking probability and the handoff call blocking probability for various traffic and mobility. We found that the proposed scheme keeps the lower probability of call blocking through the efficient channel arbitration than other suggested methods even for the irregular traffic conditions.
Reverse link analysis of CDMA cellular systems with mixed cell sizes
전형구 ; 신성문 ; 권수근 ;
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 4, 2000, Pages 481~481
The demands for mobile communication service are growing rapidly. In heavily populated areas, cell split is unavoidable to increase the capacity of the cellular system. Cell splitting makes a cellular system to have mixed cell sizes. For cell planning, it is necessary to analyze the reverse link capacity of a CDMA cellular system with mixed cell sizes. In this paper, we propose a method to calculate the reverse link capacity of a CDMA cellular system with mixed cell sizes. When a macro cell is split into three micro cells, as an example, we calculate the reverse link capacities for the three micro cells and the neighboring macro cells. The results show that as the radius of a micro cell decreases, the reverse link capacity of the micro cell increases, while those of the neighboring macro cells decrease.
Approximate Cell Loss Performance in ATM Networks: In Comparison with Exact Results
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 4, 2000, Pages 489~489
In this paper we propose an approximate method to estimate the cell loss probability(CLP) due to buffer overflow in ATM networks. The main idea is to relate the buffer capacity with the CLP target in explicit formula by using the approximate upper bound for the tail distribution of a queue. The significance of the proposition lies in the fact that we can obtain the expected CLP by using only the source traffic data represented by mean rate and its variance. To that purpose we consider the problem of estimating the cell loss measures form the statistical viewpoint such that the probability of cell loss due to buffer overflow does not exceed a target value. In obtaining the exact solution we use a typical matrix analytic method for GI/D/1/B queue where B is the queue size. Finally, in order to investigate the accuracy of the result, we present both the approximate and exact results of the numerical computation and give some discussion.
Backup Path to be satisfied QoS in ATM Network
이동욱 ; 이대영 ;
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 4, 2000, Pages 496~496
In this thesis, we propose more confidence required backup-VP allocation. First, we assigned backup VP considering Reserved resource on realtime Qos with each Qos parameter priority and then allocated backup VP of non-realtime Qos. The proposed algorithm provide more confidential backup VP by priority method for relative high cost realtime Qos error.
All Digital GMSK Modulator for the GSM Mobile System
한재충 ; 홍승억 ;
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 4, 2000, Pages 502~502
The gaussian Minimum Shift Keying (GMSK) modulation technique belongs to the class of nonlinear modulation technique, and it is known to be bandwidth efficient. The GMSK modulation is chosen for the digital cellular phone standard by the European Telecommunications Standards Institute (ETSI). In this paper, an efficient method for implementing all digital GMSK modulator is introduced. The proposed modulator is shown to be simple to implement as well as satisfying the required spectral shape recommended by the ETSI.
Verifiable Self-Certified Public Keys Scheme
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 4, 2000, Pages 512~512
Self-certified public keys, introduced by Girault allow the authenticity of public keys to be verified implicitly during the use of the keys. This paper first presents new concept of verifiable self-certified public keys and provides concrete examples satisfying our conditions. Verifiable self-certified public keys combine the benefit of certification-based schemes and Girault's self-certified public keys. Furthermore, we cryptanalyze Petersen's pseudonymous self-certified keys and present the more secure protocol.
Serially Concatenated Space-Time Code using Iterative Decoding of High Data Rate Wireless Communication
김웅곤 ; 구본진 ; 양하영 ; 강창언 ; 홍대식 ;
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 4, 2000, Pages 519~519
This paper suggests and analyzes the Serially concatenated Space-Time Code(SCSTC) with the possibility of a efficient high-speed transmission in a band limited channel. The suggested code has a structure that uses the interleaver to connect the space-time code as a inner code and the convolutional code as a outer code serially. This code keeps the advantage of high-speed transmission and also has the high BER performance. The performance of the suggested system is compared with the conventional bandwidth efficient trellis coded modulation, such as a Serially Concatenated Trellis Coded Modulation (SCTCM) and a Turbo-Trellis Coded Modulation(Turbo-TCM). The results show that the suggested system has a 2.8dB and 3dB better BER performance than SCTCM and Turbo-TCM respectively in case of the transmission rate 2b/s/Hz in fading channel.
Efficient Mobile Node Authentication Scheme Based on the Trusted Local Third Party in Mobile Computing Environments
노환주 ; 이기현 ;
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 4, 2000, Pages 528~528
Mobile computing system requires both precise identification and secure authentication scheme on remote mobile entities, which is based on the distributed mobile node. In this paper, existing discrete logarithm based Schnorr
like entity authentication schemes are improved by the analysis of performance and security on the bi-directional interactive proofs. And ElGama
like efficient authentication schemes are also proposed. Then, these are enhanced with oblivious transfer based mono-directional authentication schemes based on trusted third party for applying to the mobile agent based computing systems. Therefore, proposed schemes provide compatible performance and safety on mobile entity authentication processes.
A Design and Implementation of 64-state Viterbi Decoder with Radix-4 Method
정지원 ; 김진호 ; 김명섭 ; 오덕길 ;
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 4, 2000, Pages 539~539
A 40-Mb/s, 64-state, R=1/2, 3 bit soft decision Viterbi decoder based on Radix-4 method been designed and fabricated using a FLEX10K CPLD chip in this paper. In order to implement the high-speed Viterbi decoder, the architectures of adder-compare-select(ACS), branch metric calculation(BMC), trace back(TB) are present. In practical designed by ASIC, the speed is faster than that of CPLD by 6~7 times. Therefore, 40 Mb/s Viterbi decoder architecture can be used for high-speed wireless multimedia communications with 200 Mb/s.
Turbo MAP Decoding Algorithm based on Radix-4 Method
정지원 ; 성진숙 ; 김명섭 ; 오덕길 ; 고성찬 ;
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 4, 2000, Pages 546~546
The decoding of Turbo-Code relies on the application of a soft input/soft output decoders which can be realized using maximum-a-posteriori(MAP) symbol estimator
. Radix-2 MAP decoder can not be used for high speed communications because of a large number of interleaver block size N. This paper proposed a new simple method for radix-4 MAP decoder based on radix-2 MAP decoder to reduce the interleave block size. A branch metrics, forward and backward recursive functions are proposed for applying to radix-4 MAP structure with symbol interleaver. Radix-4 MAP decoder shall be illustratively described and its error performance capability shall be compared to conventional radix-2 MAP decoder in AWGN channel
Performance Analysis of Asymmetric Turbo Codes Using SOVA Decoding Algorithm
신한균 ; 강수훈 ; 최희동 ;
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 4, 2000, Pages 553~553
It is known that turbo codes have an error-floor bound according to the effective free distance at high SNR. But the performance for turbo codes in the water-fall area at low SNR has not been studied yet. In this paper, asymmetric turbo codes that consist of RSC(recursive systematic convolutional) codes with different constraint length are proposed and their performance is analysed for SOVA decoding algorithm.
New Test Generation for Sequential Circuits Based on State Information Learning
이재훈 ; 송오영 ;
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 4, 2000, Pages 558~558
While research of ATPG(automatic test pattern generation) for combinational circuits almost reaches a satisfiable level, one for sequential circuits still requires more research. In this paper, we propose new algorithm for sequential ATPG based on state information learning. By efficiently storing the information of the state searched during the process of test pattern generation and using the state information that has been already stored, test pattern generation becomes more efficient in time, fault coverage, and the number of test patterns. Through some experiments with ISCAS '89 benchmark circuits, the efficiency of the proposed method is shown.
10Gbps Demultiplexer using SiGe HBT
이상흥 ; 강진영 ; 송민규 ;
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 4, 2000, Pages 566~566
In the receiver of optical communication systems, a demultiplexer converts to a single data stream with a high bit rate into several parallel data streams with a low bit rate. In this paper, we design a 1:4 demultiplexer using SiGe HBT with emitter size of 2x8um². The operation speed is 10Gbps, the rise and fall times of 20-80% are 37ps and 36ps, respectively and the dissipation of power is 1.4W.
A Study on the WDM-PON System Using Shared Laser and LED Light Sources
이용기 ; 이영호 ; 박봉근 ;
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 4, 2000, Pages 573~573
This paper presents a noble optical access system using shared laser and LED light sources, which is based on WDM-PON technologies. This system adopts an external modulation of the shared laser sources for high-speed downstream and a direct modulation of the LED sources for low-speed upstream. To split or combine the transmission channels, AWG(Arrayed Wave-guide Grating) devices are used in optical cable section. The proposed system is attractive for low cost implementation. The laser light sources can share the optical carriers in the downstream scheme. Also, in upstream, the LED sources can afford to make simple of the circuits for controlling light source and of standardization for ONU(Optical Network Unit). The feasibility of the proposed system is demonstrated by several by several experiments. Our results show that the system operates well at 2.5Gbps for downstream and up to 622.08Mbps for upstream.
Study on The Blocking Performance of All-Optical Network
강안구 ; 최한규 ; 조규섭 ;
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 4, 2000, Pages 579~579
This paper analyzes and compares the blocking performancd of all-optical wavelength-routed networks providing circuit switching among users. A connection between two nodes along a particular path must use a single wavelength on all hops, or links, within the path. We then calculate the blocking probability along a lightpath with wavelength conversion in a network with an arbitrary topology and show the network performance improvement offered by node with limited translation technology. We also propose a new schematic method for the performance analysis of different types of network architecture which is composed of nodes with or without wavelength conversion(NC, FC or LC).
A Study on the PLL oscillator for K-band
이용덕 ; 장준혁 ; 류근관 ; 이기학 ; 홍의석 ;
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 4, 2000, Pages 586~586
In this paper, a PLHRO(Phase Locked Hair-pin Resonator Oscillator) for K-band is designed with the feedback property of PLL(Phase Locked Loop) Using a new tuning Mechanism. The proposed PLHRO generates the output power of -0.6 dBm at 24.42 GHz, and has the phase noise of -86.6 dBc/Hz at 100 KHz and -76.5 dBc/Hz at 10 KHz offset from carrier frequency, and has suppression characteristics of -23 dBc and spurious noise of -65 dBc. Buffered 24.42 GHz PLHRO generates the output power of 5.6 dBm at 24.2 GHz and has the of a phase noise of -77.34 dBc/Hz at 100 KHz and -72 dBc/Hz at 100 KHz offset from carrier frequency.
Design of Dynamic Route Control Gateway for High-Speed Data Communication over Public Networks
허재두 ; 강석근 ; 주언경 ;
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 4, 2000, Pages 593~593
In this paper, a dynamic route control scheme to increase speed of data communication over public network is presented. And a new structure of gateway which is suitable for the public network environments is proposed and analyzed. For dynamic allocation of transmission routing resources of the gateway and improvement of call processing ratio of the system, virtual queue is used. As results, route utilization ratio of the proposed scheme can be improved up to 60% as compared to the conventional fixed route control scheme. For the case of limited number of routes, it provides high speed data communication while maintaining delay time as low as possible. In addition, as the allocation period at call access node can be varied with the traffic in the proposed scheme, various traffics can be applied easily. Thus, it can be expected that the presented dynamic route control gateway may be suitable for application in high speed data communication over public network.
Design of a CAM-Type Traffic Policing Controller with minimum additional delay
정윤찬 ; 홍영진 ;
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 4, 2000, Pages 604~604
In order to satisfy the desired Qos level associated with each existing connection, ATM networks require traffic policing during a connection. Users who respect the contract should receive the function of transparent traffic policing without any interruption. However, contract violations should be detected and mediated immediately. So we propose a CAM type policing controller to allow user cell streams to minimize additional delay. The proposed policing scheme controls policing actions including traffic shaping by suitably spacing cells on each virtual circuits. This policing action is based on parallel processing of multiple cell stream which arrive in ATM multiplexed virtual circuits. We have developed an analytical model of the proposed policing scheme to examine the amount of cell loss and delay, which depends on traffic load, the size of policing buffers and minimum spacing cell time.
The Broadband Auto Frequency Channel Selection of the Digital TV Tuner using Frequency Mapping Function
정영준 ; 김재영 ; 최재익 ; 박재홍 ;
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 4, 2000, Pages 613~613
Digital TV tuner for 8-VSB modulation was developed with satisfying the requirements of ATSC. The double frequency conversion and the active tracking filter in the front-end were used to reduce interference of the adjacent channels and multi-channels, which suppress IF beat and image band. However, it was impossible to get frequency mapping between tracking filter and first VCO(Voltage Controlled Oscillator) in the double conversion digital TV tuner differing from conventional NTSC tuner. This paper, therefore, suggests the available structure and a new method for automatic frequency selection by obtaining the mapping of frequency characteristic over tracking voltage and the combined hardware which compose of Micro-controller, EEPROM, D/A(Digital-to-Analog Converter), OP amp. and switch driver to solve above problems.
The Study on Improvement of Traffic Rho Performance in RF Transmitter of CDMA Handset
박희봉 ; 황승훈 ; 황금찬 ;
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 4, 2000, Pages 624~624
In this paper, the phenomenon to show in CDMA handset in case of which CDMA handset do not meet Traffic Rho value of IS-98B specifications, which have minimum requirements of CDMA handset about electrical performance is analyzed. This paper proposed method to improve Traffic Rho through improving the matching circuit of TX SAW FILTER and deleting noise of LDO(Low Dropout Regulator) to generate 30.V_TX in TX block. HP8924C(CDMA Mobile Station Tester Set) and HP8595E(Spectrum Analyzer) measures the improved CDMA waveform.
Frequency-Domain Equalizer Using 2-Dimensional LMS Algorithm for DWMT Based VDSL Transceiver
박태윤 ; 최재호 ;
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 4, 2000, Pages 629~629
In this paper, we describe the structure of te DWMT (discrete wavelet multitone) transceiver for VDSL system. The DWMT transceiver consists of the transmultiplexer using cosine modulation filter bank (CMFB), time domain equalizer (TEQ) and frequency domain equalizer (FEQ) Minimizing the effects of the transmission channel. For FEQ, we have expanded the conventional 1-D linear transversal equalizer into 2-dimensions, i.e. time and subchannel axes; and we have implemented it using the 2-dimensional LMS methods. In order to qualify the performance of FEQ, we have applied it to the DWMT based VDSL transceiver and the equalizer's performance is verified by simulation using the VDSL line test model specified by the ANSI T1E1.4 requirements.
Performance Analysis of 2D-RAKE Receiver over Correlated Nakagami Fading Channel
문철 ; 강창훈 ; 박한규 ;
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 4, 2000, Pages 635~635
The average bit error rate (BER) performance of 2D-RAKE receiver, operating in a correlated Nakagami fading channel, is analyzed. The analysis assumes correlated fading between the array elements with identical fading parameters but with unbalanced average signal-to-noise ratio (SNR). And independent but non-identically distributed frequency-selective fading channel with different fading parameters is assumed. The analyses show that fading correlation, delay profile, average SNR distribution, and fading parameters of combined branches affect the overall performance of 2D-RAKE receiver.
Mobility Extension using Location Concept in Mobile Agent Languages
유재우 ; 김성근 ; 김영철 ;
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 4, 2000, Pages 640~640
Mobility in the mobile agent language is an important issue. The scope range of the agent which can move is closely related with the work which the agent can do for users. The location concept proposed in this paper can make an activity scope of agent various by defining and classifying the destination of mobile agent as a logical and physical location. We designed and implemented a java class that describes creation, deletion, and execution of agent and a service system of agent that executes the described program on the computer which is linked to network to assist the location concept. The location concept will advance the mobility of agent and this agent is expected to provide much better service for users.
Design and Implementation of a Concuuuency Control Manager for Main Memory Databases
Kim, Sang Uk ; Jang, Yeon Jeong ; Kim, Yun Ho ; Kim, Jin Ho ; Lee, Seung Seon ; Choe, Wan ;
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 4, 2000, Pages 646~646
Design and Implementation of an Index Manager for a Main Memory DBMS
김상욱 ; 염상민 ; 김윤호 ; 이승선 ; 최완 ;
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 4, 2000, Pages 661~661
The main memory DBMS(MMDBMS) efficiently supports various database applications that require high performance since it employs main memory rather than disk a primary storage. In this paper, we discuss the experiences obtained in developing the index manager of the Tachyon, a next-generation MMDMBS. The index manager is an essential sub-component of the DBMS used to speed up the retrieval of objects from a large volume of a database in response to a certain search condition. Previous research efforts on indexing proposed barious index structures. However, they hardly dealt with the practical issues occurred in implementing an index manager on a target DBMS. In this paper, we touch these issues and present our experiences in developing the index manager on the Tachyon as solutions. The main issues touched are (1) compact representation of an index entry, (2) support of vaiable-length keys, (3) support of multiple-attribute keys, (4) support of duplicated keys, (5) definition of external AOIs, (6) concurrency control, and (7) backup and recovery, We believe that our contribution would help MMDBMS developers highly reduce their trial-and-errors.
A New Implementable Scheduling Algorithm Supporting Various Traffics in ATM Networks
심재정 ; 이원호 ; 변재영 ; 고성제 ;
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 4, 2000, Pages 675~675
In this paper, we propose a new scheduling algorithm called the Adaptive Weighted Round Robin with Delay Tolerance (AWRR/DT). The proposed scheme is based on the per-class queueing mechanism in which a number of connections of similar characteristics are multiplexed into one class-queue. Traffic classes of the proposed method are classified into a single non-real-time traffic class. the proposed scheme determines the weights of classes according to the input traffic and delay characteristics of each class at the beginning of every cycle. Furthermore, this scheme incorporates a cell discarding method to reduce the QoS degradation that may be incurred by congestion of networks. We have evaluated the proposed scheme through discrete-event simulation. Simulation results indicate that the proposed scheme can reduce the average delay of non-real-time class while maintaining the QoS of real-time classes. The proposed algorithm can be effectively applied to high-speed networks such as ATM networks.
Intelligent Modelling Techniques Using the Neuro-Fuzzy Logic Control in ATM Traffic Controller
이배호 ; 김광희 ;
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 4, 2000, Pages 683~683
In this paper, we proposed the cell multiplexer using Hopfield neural network and the bandwidth predictor using the backpropagation neural network in order to make an accurate call setup decision. The cell multiplexer controls heterogeneous traffic and the bandwidth predictor estimates minimum bandwidth which satisfies traffic's QoS and maximizes throughput in network. Also, a novel connection admission controller decides on connection setup using the predicted bandwidth from bandwidth predictor and available bandwidth in networks. And then, we proposed a fuzzy traffic policer, when traffic sources violate the contract, takes an appropriate action and a improved traffic shaper, which controls burstness which is one of key characteristics in multimedia traffic. We simulated the proposed controller. Simulation results show that the proposed controller outperforms existing controller.
Performance Analysis of LAN Interworking Unit for Capacity Dimensioning of Internet Access Links
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 4, 2000, Pages 692~692
We build and analyze some types of queueing model to discuss capacity dimensioning of access links of a LAN interworking unit connected to the Internet backbone network. We assume that the IWU has a FIFO buffer to transmit IP packets to the Internet through the backbone. In order to analyze the system, we use a Poisson process and an MMPP process as input traffic models of IP packets and we use a general service time distribution as a service time model. But we use both an exponential service time and a deterministic service time in numerical examples for simple and efficient performance comparisons. As performance measures, we obtain the packet loss probability and the mean packet delay. We present some numerical results to show the effect of arrival rate, buffer size and link capacity on packet loss and mean delay.
A Study on Implementation and Design of Secure VOD System
한성민 ; 유황빈 ;
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 4, 2000, Pages 700~700
In this paper, we address vulnerabilities of legacy VOD system and implement secure-VOD system to protect security holes of it. Our secure-VOD system provide user authentication using one-time password, message authentication and encryption/decryption for video server information. To improve security of existing fixed password system, our secure-VOD system use one-time password. Also, our secure-VOD system provides integrity for video server information by generating and verifying message authentication code using HMAC-HAS160 algorithm, our secure-VOD system RC5 encryption algorithm to guarantee confidentiality for video server information.
VLSI Array Architecture for High Speed Fractal Image Compression
성길영 ; 이수진 ; 우종호 ;
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 4, 2000, Pages 708~708
In this paper, an one-dimensional VLSI array for high speed processing of fractal image compression algorithm based the quad-tree partitioning method is proposed. First of all, the single assignment code algorithm is derived from the sequential Fisher's algorithm, and then the data dependence graph(DG) is obtained. The two-dimensional array is designed by projecting this DG along the optimal direction and the one-dimensional VLSI array is designed by transforming the obtained two-dimensional array. The number of Input/Output pins in the designed one-dimensional array can be reduced and the architecture of process elements(PEs) can be simplified by sharing the input pins of range and domain blocks and internal arithmetic units of PEs. Also, the utilization of PEs can be increased by reusing PEs for operations to the each block-size. For fractal image compression of 512×512 gray-scale image, the proposed array can be processed fastly about 67 times more than sequential algorithm. The operations of the proposed one-dimensional VLSI array are verified by the computer simulation.
3-D Subband Filter Banks for Lossless Compression of Volumetric Images
홍승표 ; 정호열 ; 최태영 ;
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 4, 2000, Pages 715~715
This paper presents 3-D subband filter banks which are effective for progressive and lossless compression of volumetric images. For such a purpose, ORT(Overlapping Rounding Transform), applied so far to 1-D lossless subband filter banks, is now used to implement two types of 3-D lossless subband filter banks: separable and non-separable types. Separable filter banks are implemented form applying 1-D lossless filter banks consecutively. Non-separable filter banks are developed by expanding the 1-D ORT into 3-D one. In particular, the proposed ORT based 3-D non-separable filter banks generalizes the 3-D HINT(Hierarchical INTerpolation) algorithm. Through the experiment comparisons on various volumetric medical images, we prove that the proposed separable/non-separable filter banks perform better, in terms of compression ratio (first order entropy), than the other lossless compression techniques such as block based transform and conventional 3-D HINT.
Texture Coding in MPEG-4 Using Modified Boundary Block Merging Technique
김두석 ; 고형화 ;
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 4, 2000, Pages 725~725
In this paper, we propose a modified boundary block merging technique for the texture coding of MPEG-4, We propose an ORP(Optimized Region Partitioning) method that partition the VOP-based reference position to minimize the number of coding blocks. The merging possibility is improved by adding +90˚ and -90˚ rotation merging. We propose a MRM(Multiple Rotation Merging) method which applies the rotation merging in the order of 180˚, +90˚ and -90˚. If a pair of boundary blocks has low correlation, existing BBM's padding technique is not efficient. Our padding after merging method give better result even if it has low correlation. The proposed method showed 5~8(%) coding bit reduction at the same PSNR values compared to BBM method.
A Study on Assembly Part Recognition Using Part-Based Superquadric Model
이선호 ; 홍현기 ; 최종수 ;
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 4, 2000, Pages 734~734
This paper a new volumetric approach to 3D object recognition by using PBSM (part-based superquadric model). The assembly part object can be constructed with the set of volumetric primitives and the relationships between them. We describe volumetric characteristics of the model object with superquadric parameters. In addition, our model base has the relationships between volumetric primitives as well as the surface information: the surface type, the junction type between neighboring surfaces. These surface properties and relationships between parts are effectively used in recognition process. Our integrated method is robust to recognition of the identity, position, and orientation of randomly oriented assembly parts. Furthermore, we can reduce the effects of self-occlusion and non-linear shape changes according to viewpoint. In this paper, we show that our integrated method is robust to recognition of the identity, position, and orientation of randomly oriented assembly parts through experimental results.
Image Compression Based on Wavelet Transform Using Shffling and Bit Plane Correlation
김승종 ; 정제창 ; 최병욱 ;
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 4, 2000, Pages 743~743
In this paper, we propose wavelet transform inage compression method using shuffling and bit plane correlation. Proposed method is that original image decompose into multiresolutions using biorthogonal wavelet transform with linear phase response property and decomposed subbands are classified by maximum classification gain. And classified data sets in each subband are quantized using arbitrary set optimum bit allocation method. Quantized data sets in each subband are shuffled and context based bit plane arithmetic encoded. In context based bit plane arithmetic encoding, the context for each subband is not assigned unifomly, but assigned according to maximum correlation direction. Our results are comparable, or superior for some images at low rates, to published state-of-the-art coders.
Entropy Coders Based on Binary Forword Classification for Image Compression
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 4, 2000, Pages 755~755
Entropy coders as a noiseless compression method are widely used as end-point compression for images so there have been many contributions to increase of entropy coder performance and to reduction of entropy coder complexity. In this paper, we propose some entropy coders based on binary forward classification (BFC), BFC requires overhead of classification but there is no change between the amount of input information and that of classified output information, which we prove this property in this paper. And using the proved property, we propose entropy coders which are Golomb-Rice coder after BFC (BFC+GR) and arithmetic coder with BFC (BFC+A). The proposed entropy decoders do not have further complexity from BFC. Simulation results also show better performance than other entropy coders which have similar complexity to proposed coders.
Residual Image Compression based on Wavelet Transform
정한조 ; 유지상 ; 김은수 ;
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 4, 2000, Pages 763~763
An Efficient Hardware-Software Co-Implementation of an H.263 Video Codec
장성규 ; 김성득 ; 이재헌 ; 김진수 ; 정의철 ; 최건영 ; 김종대 ; 나종범 ;
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 4, 2000, Pages 771~771
In this paper, an H.263 video codec is implemented by adopting the concept of hardware and software co-design. Each module of the codec is investigated to find which approach between hardware and software is better to achieve real-time processing speed as well as flexibility. The hardware portion includes motion-related engines. such as motion estimation and compensation, and a memory control part. The remaining portion of the H.263 video codec is implemented in software using a RISC processor. This paper also introduces efficient design methods for hardware and software modules. In hardware, an area-efficient architecture for the motion estimator of a multi-resolution block matching algorithm using multiple candidates and spatial correlation in motion vector fields (MRMCS), is suggested to reduce the chip size. Software optimization techniques are also explored by using the statistics of transformed coefficients and the minimum sum of absolute difference (SAD) obtained from the motion estimator.
A Proposal for Hit Ratio Improvement of a Microprocessor's Cache Memory
조용훈 ; 김정선 ;
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 4, 2000, Pages 783~783
A microprocessor, which is used as a CPU for state-of -the-art personal computers, adopts 256KB or 512KB L2(Level 2) cache memory. This cache hires Direct Mapping Procedure, 32B Line Size, and no Write Allocation. In this cache architecture, we can expect about 2.5% hit ratio improvement by using 8-way Set Associative Mapping instead of Direct Mapping, 128B Line Size instead of 32B, and Write Allocation.
Low-noise VLSI Implementation of Pipelined IIR Filters
태기철 ; 최정필 ; 신승철 ; 정진균 ;
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 4, 2000, Pages 788~788
Scattered look-ahead pipelining method can be efficiently used for high sample rate or low-power applications of digital recursive filters. Although the pipelined filters are guaranteed to be stable by this method, these filters suffer from large roundoff noise when the poles are crowed within some critical regions. To avoid this problem, a low-noise implementation technique was proposed using constrained Remez exchange algorithm. By the constrained filter design approach, the desired filter spectrum is satisfied while some of the pole angles are constrained to avoid pole crowding within critical regions. In the proposed approach, to obtain improved spectrum characteristics or better roundoff noise properties, the radius of the angle-constrained pole is optimized depending on the direction of the pole movement.