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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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The Korean Institute of Communications and Information Sciences
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Volume & Issues
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
Volume 25, Issue 3B - Mar 2000
Volume 25, Issue 3A - Mar 2000
Volume 25, Issue 1B - Jan 2000
Volume 25, Issue 1A - Jan 2000
Volume 25, Issue 9 - 00 2000
Volume 25, Issue 8 - 00 2000
Volume 25, Issue 7 - 00 2000
Volume 25, Issue 5 - 00 2000
Volume 25, Issue 4 - 00 2000
Volume 25, Issue 2B - 00 2000
Volume 25, Issue 2A - 00 2000
Volume 25, Issue 1 - 00 2000
Volume 25, Issue 12 - 00 2000
Volume 25, Issue 10 - 00 2000
Selecting the target year
A Study on Miniature VCO for 1.6GHz PCS Phone
권원현 ; 김운용 ;
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 7, 2000, Pages 935~935
In this paper, miniature voltage-controlled oscillator(VCO) for 1.6GHz PCS band is designed and implemented. Colpitts type LC resonating oscillator is designed with multilayer PCB and circuit parameters are optimized using the circuit simulator. Using the optimized design parameters, miniature VCO with 6×6×1.8mm³ (0.065cc) dimensions is fabricated and experimented. Developed VCO has -1.67dBm ±0.5dBm output power level in 52.5MHz tunung range, and has -99.33dBc/Hz phase noise performance at 10 KHz frequency offset.
Performance of Multi-rate Optical Wireless PPM-CDMA System over an Indoor Non-directed Diffuse Channel
Hwang, Seong Su ; Lee, Jae Hong ;
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 7, 2000, Pages 943~943
Multihop Connection Establishment Algorithms in Wavelength-Routed Optical Networks
Kim, Sang Wan ;
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 7, 2000, Pages 951~951
RCPT Code Design for Video Transmission
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 7, 2000, Pages 960~960
It is essential to develop the robust video transmission system over wireless channel, since the effect of the noise and the interference to compressed video may be fatal. In this paper, we have designed turbo code, which is adequate for the transmission of video and analyzed the performance of that. Especially, we have focused the rate compatible punctured turbo(RCPT) coed, which has rate compatible(RC) property for unequal error protection(UEP). It has been shown through computer simulation that the turbo code with helical interleaver yields better performance than those with other interleavers when the size of the interleaver is not large.
The LMI cixed H₂/
control of inverted pendulum system using LFR
Park, Jong U ; Lee, Sang Cheol ; Lee, Sang Hyo ;
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 7, 2000, Pages 967~967
Performance Improvement of the QAM System using the Dual-Mode NCMA and DPLL
강윤석 ; 안상식 ;
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 7, 2000, Pages 978~978
Blind equalizers recover the transmitted data using statistical characteristics of the signal alone. Among many alternatives, steepest gradient descent type algorithms such as the CMA and Sato algorithm are most widely utilized in practice. In this paper we propose a dual-mode NCMA algorithm, which combines the advantages of the dual-mede CMA and Normalized CMA (NCMA) with the dual-mode phase recovery algorithm. In addition, we perform computer simulations to demonstrate the performance improvement of the proposed algorithm with a QAM system. Simulation results show that the presented algorithm has a faster convergence speed and smaller steady-state residual error than the CMA and dual-mode CMA.
A Novel Spectral Analysis of Ultrashort Pulse Transmission Using the Pulse-Ordering Concept
민재홍 ; 정희창 ; 오용선 ; 전진성 ;
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 7, 2000, Pages 986~986
In this paper, we analyze transmission characteristics of ultrashort laser pulses using the properties of high-order pulses which are systematically obtained following their orders. The high-order pulses are easily derived from a modified PRS system model. But we make clear they are very useful to cover wider area and to show more accurate transmission characteristics of ultrashort pulses than Gaussian or Sech pulse approximations used conventionally. These are based on the fact that the spectra and bandwidths of the high-order pulses are geautifully related to their orders. First modifying the generalized PRS system model, we propose a new model for deriving any type of high-order pulse. And we offer a novel analysis method of ultrashort pulse transmission varying the order of the pulse from n=1 to n=100, we obtain spectra of ultrashort pulses with 1(ps)∼150(fs) FWHM's, which are widely used in optical pulse communications. One-step further, we derive PSD's of their pulse-tr ins when they are applied to Unipolar signaling scheme. These PSD's are decided in the range of possible pulse intervals. All of these results are not only coincided with some conventional experimental works but will be applied to any pioneering ultrashort pulse in the future.
Implementation of UEP using Turbo Codes and EREC Algorithm for Video Transmission
Sim, U Seong ; Heo, Do Geun ;
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 7, 2000, Pages 994~994
Region Segmentation and Volumetry of Brain MR Image represented as Blurred Gray Value by the Partial Volume Artifact
성윤창 ; 송창준 ; 노승무 ; 박종원 ;
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 7, 2000, Pages 1006~1006
This study is to segment white matter, gray matter, and cerebrospinal fluid(CSF) on a brain MR image and to calculate the volume of each. First, after removing the background on a brain MR image, we segmented the whole region of a brain from a skull and a fat layer. Then, we calculated the partial volume of each component, which was present in scanning finite thickness, with the arithmertical analysis of gray value from the internal region of a brain showing the blurring effects on the basis of the MR image forming principle Calculated partial volumes of white matter, gray matter and CSF were used to determine the threshold for the segmentation of each component on a brain MR image showing the blurring effects. Finally, the volumes of segmented white matter, gary matter, and CSF were calculated. The result of this study can be used as the objective diagnostic method to determine the degree of brain atrophy of patients who have neurodegenerative diseases such as Alzheimer's disease and cerebral palsy.
Vertex-based shape coding based on the inter-segment distance
이진학 ; 정재원 ; 문주희 ; 김재균 ;
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 7, 2000, Pages 1017~1017
In this paper, we propose a new coding method based on the distance between vertex segments for vertex positions in the vertex-based shape coding. The pixel lines are divided into the segments of a fixed length, and the segments that have vertex pixels are called vertex segments. We analyze the probability distribution of the relative distance between vertex segments and prove that it depends only on the ratio between the number of vertices and the number of segments. Considering the coding efficiency and implementation complexity, we choose a particular ratio to make a code table. For each input image, the segment size is chosen according to the ratio, and relative segment distances are entropy coded. It is shown that the proposed method is efficient for the images with many vertices.
An Error-Resilient Image Compression Base on the Zerotree Wavelet Algorithm
장우영 ; 송환종 ; 손광훈 ;
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 7, 2000, Pages 1028~1028
In this paper, an error-resilient image compression technique using wavelet transform is proposed. The zerotree technique that use properties of statistics, energy and directions of wavelet coefficients in the space-frequency domain shows effective compression results. Since it is highly sensitive to the propagation of channel errors, even a single bit error degrades the whole image quality severely. In the proposed algorithm, the image is encoded by the SPIHT(Set Partitioning in Hierarchical Trees) algorithm using the zerotree coding technique. Encoded bitstreams are partitioned into some blocks using the subband correlations and then fixed-length blocks are made by using the effective bit reorganization algorithm. Finally, an effective bit allocation technique is used to limit error propagation in each block. Therefore, in low BER the proposed algorithm shows similar compression performance to the zerotree compression technique and in high BER it shows better performance in terms of PSNR than conventional methods.
Object-based Digital Watermarking Using Wavelet Property
김유신 ; 원치선 ; 이재진 ;
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 7, 2000, Pages 1037~1037
In this paper we present an object-based watermarking scheme, which cuts out several featured portions from an image and casts chaotic sequences as a watermark into the extracted object image in the discrete wavelet domain with respect to the models of the human visual system. In such a way we can insert watermark to several objects of an image separately. Advantages of the proposed scheme include that it can protect featured object out of an image selectively as well as entire image and casts watermark sequences according to human visual masking utilizing the time-frequency localization property of the wavelet transform.
Image Retrieval using Statistical Property of Projection Vector
권동현 ; 김용훈 ; 배성포 ; 이태흥 ;
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 7, 2000, Pages 1044~1044
Projection that can be used as a feature for image representation, includes much available informations such as approximated shape and location. But when we retrieve image using it, there are some disadvantage such as requiring much index data and making different length of projected vector for differenr image size. In order to overcome these problems, we propose a method of using block variance for the projected vector. We use block variance of the projection vector to localize the characteristics of image and to reduce the number of index data in database. Proposed algorithm can make use of statistical advantage through database including various size of images and be executed with fast response time in implementation.
A Study For Automobile License Plate Extraction Using DCT and Correlation
경보현 ; 손태주 ; 남궁연 ; 남궁재찬 ;
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 7, 2000, Pages 1050~1050
In this paper, We propose the automobile license plate extraction method using Discrete Cosin Transform and Correlation from automobile image obtained through digital camera. The automobile license plate is consisted of the character and rectangle background of it. We extracted the automobile edge image by the DCT processing of automobile image and Obtained the automobile license plate from the automobile edge image by Correlation processing. We separated characters from automobile license plate using the projection histogram. Compare to the previous methods, we obtained the good result from extracting the automobile license plate at night, very strong light and bad weather.
Development of 60GHz Millimeter-wave Transmitter using NRD Guide
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 7, 2000, Pages 1057~1057
Allow me to introduce the development of an FM transmitter. The transmitter uses millmeter waves at the frequency of 60 GHz, and it can produce as much as 20 mW power with the band width of 1 GHz. The great feature of the FM transmitter is that it has been created by the special technique of utilizing the NRD (non radiative dielectric) waveguide. The advantage of adopting the NRD waveguide is that it can significantly reduce transmission loss. We can construct a small-size NRD guide transmitter in a simple way that has superb transmission performance. The NRD guide transmitter is very useful for CATV transmission or transmission over a wide range. In addition, the transmitter has almost the same band width as optical communication, and the data transmission speed of the transmitter is faster than that of optical communication. A transmitter with these merits would be highly appreciated as a way of ultra-highspeed communication network over short distances.
The Error concealment using Scalability in H.236v2
한승균 ; 장승기 ; 서덕영 ;
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 7, 2000, Pages 1063~1063
This paper proposes an adaptive error concealment technique for compressed video. Since redundancy is extracted out during compression process, compressed video is vulnerable to errors which occur during transmission of video over error prone networks such s wireless channels and Internet. Error concealment is a process of reconstructing video out of damaged video bit stream. We proved that scalable encoding is very useful for error concealment. Analysis of experiments shows that some part of image is better concealed by using base layer information and other part of image is better concealed by using previous frame information. We developed a technique which enables to decide which methodology is more effective, adaptively, based on motion vectors and regional spatial activity. We used H.263v2 for scalable encoding, but, our approach could be applied to all DCT based video codec.
Vertical Edge Based Algorithm for Korean License Plate Extraction and Recognition
Mei Yu ; 김용택 ;
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 7, 2000, Pages 1076~1076
Vehicle license plate recognition identifies vehicle as a unique, and have many applications in traffic monitoring field. In this paper, a vertical edge based algorithm to extract license plate within input gray-scale image is proposed. A size-and-shape filter based on seed-filling algorithm is applied to remove the edges that are impossible to be the vertical edges of license plate. Then the remaining edges are matched with each other according to some restricted conditions so as to locate license plate in input image. After license plate is extracted. normalized and segmented, the characters on it are recognized by template matching method. Experimental results show that the proposed algorithm can deal with license plates in normal shape effectively, as well as the license plates that are out of shape due to the angle of view.
CLR Performance of Random Traffic in Wireless ATM Access Network
이하철 ; 이병섭 ;
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 7, 2000, Pages 1153~1153
In this paper we describe our investigation on ATM(Asynchronous Transfer Mode) CLR(Cell Loss Rate) in the wireless ATM access network which consists of access node wireless link, where focus on the impact of the bit error characteristics of a wireless link on ATM. We first analyze the CLR performance of access node for ATM random traffic, using M/D/1 queueing system and secondly analyze ATM header error correction (HEC) mechanism and calculate ATM CLR for a wireless link. In the second part of the paper we suggest possible error control architecture to improve performance degradation caused by wireless link errors. Finally this paper provides performance results through analysis and simulation for FEC schemes which are appropriate for random ATM traffic and provides performance comparison among FEC schemes through the use of BER and CLR parameter.
A Study on the Relation of CLR and Blocking Probaility for ATM Traffic in the Wireless ATM Access Network
이하철 ; 이병섭 ;
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 7, 2000, Pages 1167~1167
In this paper it is focused on the relation between CLR(Cell Loss Ratio) and blocking probability in the wireless ATM(Asynchronous Transfer Mode) access network which consists of access node and wireless channel. Traffic model of wireless ATM access network is based on the cell scale, burst scale and call connection level. The CLR equation due to buffer overflow for wireless access node is derived for VBR(Variable Bit Rate), CBR(Constant Bit Rate) and random traffic. The CLR equation due to random bit errors and burst errors for wireless channel is derived. Using the CLR equation for both access node and wireless channel, the CLR equation of wireless ATM access network is derived. The relation between CLR and blocking probability is analyzed for VBR, CBR and random traffic to evaluate CLR performance of wireless ATM access network.
An Efficient Mobility Management using layered Sub-LA Strategy for Cellular Mobile Radio Systems
박상준 ; 김병기 ;
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 7, 2000, Pages 1178~1178
This paper presents layered Sub-LA strategy for efficient mobility management in cellular mobile radio systems. An efficient mobile location tracking strategy should minimize the combined cost of paging and location update. This combined cost depends on a mobile's mobility as well as its incoming call arrival rate. Also, we must derive the optimal location area (LA) size, so that minimize the combined cost. We introduce the exist location tracking strategies, and we derive the optimal location area size for the fixed location area (FLA) strategy and the distance-based location area (DBLA) strategy using the fluid mobility model. We then compared these two strategies to Sub-LA strategy. And, Numerical examples show that the Sub-LA strategy gives better performance than the FLA and the DBLA strategies in many cases.
Performance Analysis of On Board Processing in Communication Satellite Against Jamming Environment
권오주 ; 이광억 ; 하영호 ;
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 7, 2000, Pages 1185~1185
In this paper, the bit error probability performance of the Band Pipe Transponder(BPT), Dehop Only Transponder(DOT), Dehop Rehop Transponder(DRT), and Symbol Regenerative Transponder(SRT) to determine the military satellite on-board processing(OBP) method in the full band noise(FBN) nd partial band noise(PBN) is obtained and analyzed. In the PBN environment, it is impossible for all of the OBP methods to communicate for that diversity is equal to 1 but the bit error probability performance of the DRT and SRT can be improved by increasing diversity value. The performance of the SRT is a little more excellent than the DRT's. And then DRT can be considered for the satellite communication method from this point of flexibility.
An Efficient SIR Estimation and Channel Estimation Algorithm considering Power Control in CDMA Systems
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 7, 2000, Pages 1194~1194
In this paper, we propose an efficient SIR estimation method which doesn't use channel value. The proposed SIR estimation method has identical SIR value as the conventional method and is more efficient than the conventional one in terms of the complexity of computation. Meanwhile, in the case of power controlled system, statistical characteristics of fading channels are destroyed. Therefore, we propose a modified channel estimation scheme in power controlled systems and also analyze performance of the proposed channel estimation scheme through computer simulation. From simultion results, we verify that the proposed channel estimation scheme has superior performance as Doppler frequency increases.
A research on the reasonable mobile phone sale subsidy: in comparison with foreign cases
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 7, 2000, Pages 1204~1204
In this paper, I researched the actual state of the domestic and foreign mobile phone sale subsidy. By comparing with the foreign cases, I proposed the realizable and healthy polishes to he mobile phone service companies. And I researched to understand the agent and circulation structure of mobile phone. To propose the desirable sale subsidy polish, I analyze the number of subscriber, sales amount, and total sale subsidy of individual service company. The competition between the service company is the reason of the large sale subsidy, the accumulated sale subsidy comes out the cause of the service company's loss. Thus the objective and importance of this research is the computation of the pertinent subsidy. By using the average revenue per user(ARPU) and the total sale subsidy of the domestic and foreign major service companies, I tried to compute the period that the sale subsidy is withdrawn and propose the reasonable mobile phone sale subsidy.
Interlligent Traffic Control with the Buffer Occupancy in ATM Networks
허선동 ; 박동선 ;
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 7, 2000, Pages 1215~1215
In this paper, we propose an intelligent policing algorithm based on the window mechanism. While previous mechanisms are limited to use the only source parameters, the proposed algorithm utilized an additional parameter obtained from the network side to consider the current state of the link. The additional parameter is the buffer occupancy which represents the current occupation rate of an ATM switching node. For the efficient control of the source traffics, the algorithm determines the number of cells allowed in the next window using the fuzzy logic. The simulation results for the proposed algorithm show that the algorithm performs well for the basic requirements as the previous fuzzy mechanism. And the variance of the number of cells in the multiplexer is much stabilized, comparing to other algorithms by including the proposed buffer occupancy. From that point, we can recognize that the proposed algorithm has the additional advantage that the network has the better condition in avoiding the congestion with the feedback information, the buffer occupancy.
Delay Performance Analysis of Signalling Network Functions in Common Channel Signalling System
박철근 ; 정태욱 ; 이유태 ;
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 7, 2000, Pages 1226~1226
As all delays resulting from the signalling network directly affect the response time of network management activity, all control informations have to be transported most efficiently. It is very important to know the performance of the signalling system not only because of smooth network operation but also because of efficient engineering of signalling networks. In this paper, we analyzed delay performance of signalling network functions in common channel signalling system. Analysis was accomplished through the queueing model that was based on the ITU-T specification and was independent of other layer's protocol. Also we modeled it considering that signalling network functions is divide into signalling message handling part and signalling network management part.
Performance of Frame Distribution Schemes for MAC Controllers with the Link Aggregation Capability
전우정 ; 윤종호 ;
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 7, 2000, Pages 1236~1236
This paper deals with the IEEE802.3 link aggregation technology which enables to increase the bandwidth of LAN by emulating several physical links as a single link. Noting that the operation of the technology is depending on LAN configurations, we propose two tframe distribution schemes, and analyze their performance using SIMULA. For the link aggregation between switches. or between a switch and a serve, we first present a dynamic frame distribution scheme. When a specified port encounters a heavy traffic, this method allocates the least utilized link to handle the traffic in parallel. To keep the frame order while the new link being allocated, we employ a special flush buffer. From the simulation results, we can show that the proposed scheme can achieve lower frame loss rate than the generic technology. For the link aggregation between end systems, we also note that the out-of-order frame delivery might be the crucial problem. To keep frame orders, we present three methods such as padding, tagging, and segmentation. From the simulation results, one can see that the segmentation method outperfroms among others, and the padding method might also be advantageous on its feasibility.
Mail Auto-push Service System in an Internet Auction using MIME Protocol
이근왕 ; 이종희 ;
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 7, 2000, Pages 1244~1244
The existing internet auction systems have adopted the form which gives a win to the auction bidder who proposes the top bid price for the goods posted on th auction board. But it hasn't been satisfying the one-step processing to the user convenience requiring keeping the consistent care of user's for bidding and checking as well as neglecting the convenience of user interface while participating in the electronic bidding system. Currently, existing internet auction systems are known as the representative internet auction system, and it has the merit allowing the various bidding kinds. But it does not support the automatic process which can replaces what the user has to do using an agent. To improve this kind of user interface, we propose an automatic bidding price strategy algorithm which composes the auction system using agent so that it can replace the user's bidding activity. This algorithm gives an auction system the efficient bidding price policy. Also, participants of internet auction are serve auction all of service in the internet auction agent system by reply for mail form using MIME protocol.
Automatic Generation of Protocol Test Sequences from SDL
이현정 ; 최영일 ; 이병선 ;
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 7, 2000, Pages 1253~1253
Conformance test verifies that a protocol implementation conforms to the protocol specification. The quality of the conformance test depends on the test sequence. Existing test sequence generation methods have potential errors because they are manually done. In this paper, we propose an automatic generation of protocol test sequences from SDL using Design/CPN, which has extended test coverage. We transform SDL into CPN form with data flow, and apply it to Design/CPN. Our method has test sequences with partial data flow and reduces errors compared with existing manual method.
TCP Vegas RTT Ambiguity Problem and Its Solutions
김종덕 ; 김종권 ;
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 7, 2000, Pages 1260~1260
Vegas is an implementation of TCP using RTT measurement for he detection of network congestion and decides the congestion control parameters, such as window size, based on it. there are several research results showing that Vegas achieves better throughput and higher fairness than the existing TCP implementations, such as Tahoe, Reno. However we have noticed that Vegas poorly reflects the asymmetric characteristic of TCP data transfer because of the wrong interpretation of RTT which reflects backward link state as well as forward link state. We named this problem as "Vegas RTT Ambiguity Problem" and developed 2 solutions. one is "Small Get Priority Queue", a packet scheduling technique in router, and the other is "Modified Vegas" using TCP Timestamp Option. We used simulation to show the problem and to verify the solutions.
Performance Analysis of the Adaptive Coding System Based on Received SNR over a Rayleigh Fading Channel
허성호 ; 이재홍 ;
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 7, 2000, Pages 1270~1270
In this paper, an adaptive coding system is analyzed over a Rayleigh fading channel for digital communication without retransmission, which operates based on a received signal to noise ration (SNR). For the analysis, a finite-state Markov channel model is used for a Rayleigh fading channel, which is constructed by dividing the value of a received SNR into K intervals. Taking the types of errors at the prediction process into account, the average bit error probability and the average throughput are computed for the adaptive coding system. Numerical results are shown, which uses the punctured convolutional codes as a coding scheme whose code rates are simple to be changed. It is shown that the adaptive coding system based on a received improves the performance of the system.
LQ-servo Design Method Using Convex Optimization (Ⅰ) Frequency Domain Approach
Lee, Eung Seok ; Seo, Byeong Seol ;
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 7, 2000, Pages 1282~1282
Frame-Weighted Scheduling for Connectionless Services in ATM Networks
호경중 ; 김성철 ;
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 7, 2000, Pages 1292~1292
In this paper, we consider the problem caused when a connection-oriented ATM network supports connection-less IP traffic in a buffer usage aspect. In processing cells in conventional ATM network, GPS-related scheduling schemes are used to satisfy the fairness principle. We argue that GPS-related scheduling disciplines are good in pure ATM networks, but in supporting IP traffic these disciplines lead to inefficiency, high cell loss rate and much delay. We propose an alternative scheduling discipline in which we schedule cells with respect to IP packets and weight the priority of cells in the same IP packet until the end cell of a packet is processed. We show that shortens the time in which IP packets stay in network, thus can lower the usage of buffers. We demonstrate the effect of our schefuling principle through simulation.
Block Turbo Codes Using Efficient Reduced Search Trellis Decoding Method
김수영 ; 이수인 ;
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 7, 2000, Pages 1301~1301
In this paper, block turbo codes using trellis decoding method is introduced. Performance simulations of block turbo codes with various modifications of constituent codes and concatenation methods are demonstrated with theoretical performance bounds. An efficient complexity reduction method for trellis decoding is also introduced. Simulation results on an AWGN channel shows that the performance of the proposed complexity reduction method could approximate to that of the exhaustive search method with only 1/10 of the full load.
A Study on VC merge Scheme for Multi-class Traffic using Dynamic Bandwidth Allocation in MPLS Networks
이수경 ; 오경희 ; 손홍세 ; 송주석 ;
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 7, 2000, Pages 1313~1313
The realization of scalable layer 3 switching over ATM networks requires merging of virtual connections to be possible. This capability, known as VC merging, cannot be provided by ATM networks which use a standard ATM protocol stack on both switches and stations. Though a few VC merging schemes are proposed, they support best-effort alone there has been no concrete mechanism for multiple classes. This paper propose a dynamic bandwidth allocation, when non best-effort traffic flows are merged. It would be possible to guarantee the Qos of the VC merged traffic through the dynamic allocation. In addition, the proposed dynamic VC bandwidth allocation method is demonstrated by simulations.
New Peak-to-Average Power Ratio Reduction Scheme for an OFKM-CDMA System
주양익 ; 이연우 ; 차균현 ;
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 7, 2000, Pages 1320~1320
A very simple and effective peak power reduction scheme for a downlink OFDM-CDMA system is proposed using the relationship between peak-to-average power ratio (PAPR) and out-of-phase autocorrelation. Since power spectrum and autocorrelation function are Fourier transform pair, the PAPR property of the sequences can be estimated by the out-of-phase autocorrelation function of the spreading sequences. Thus, by scrambling the spread data in the frequency domain, we can reduce the sidelobe energy of autocorrelation, and at last, suppress PAPR in the proposed OFDM-CDMA system.
Design and Fabrication of Ka Band MMIC LNA for LMDS LNA
The Journal of Korean Institute of Communications and Information Sciences, volume 25, issue 7, 2000, Pages 1326~1326
A Ka band MMIC LNA for LMDS was designed and fabricated. P-HEMT was used as the active devices and microstripline was used as the passive elements to design LNA instead of spiral inductors and MIM capacitors which are used for passive devices in low frequency MMIC's because of high frequencies. RC feedback circuit and source inductor were used to increase stability and to reduce noise figure. Four stage amplifier gives 27.4dB gain and 3.46dB noise figure at 26.5GHz.