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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 31, Issue 12C - Dec 2006
Volume 31, Issue 12B - Dec 2006
Volume 31, Issue 12A - Dec 2006
Volume 31, Issue 11C - Nov 2006
Volume 31, Issue 11B - Nov 2006
Volume 31, Issue 11A - Nov 2006
Volume 31, Issue 10C - Oct 2006
Volume 31, Issue 10B - Oct 2006
Volume 31, Issue 10A - Oct 2006
Volume 31, Issue 9C - Sep 2006
Volume 31, Issue 9B - Sep 2006
Volume 31, Issue 9A - Sep 2006
Volume 31, Issue 8C - Aug 2006
Volume 31, Issue 8B - Aug 2006
Volume 31, Issue 8A - Aug 2006
Volume 31, Issue 7C - Jul 2006
Volume 31, Issue 7B - Jul 2006
Volume 31, Issue 7A - Jul 2006
Volume 31, Issue 6C - Jun 2006
Volume 31, Issue 6B - Jun 2006
Volume 31, Issue 6A - Jun 2006
Volume 31, Issue 5C - May 2006
Volume 31, Issue 5B - May 2006
Volume 31, Issue 5A - May 2006
Volume 31, Issue 4C - Apr 2006
Volume 31, Issue 4B - Apr 2006
Volume 31, Issue 4A - Apr 2006
Volume 31, Issue 3C - Mar 2006
Volume 31, Issue 3B - Mar 2006
Volume 31, Issue 3A - Mar 2006
Volume 31, Issue 2C - Feb 2006
Volume 31, Issue 2B - Feb 2006
Volume 31, Issue 2A - Feb 2006
Volume 31, Issue 1C - Jan 2006
Volume 31, Issue 1B - Jan 2006
Volume 31, Issue 1A - Jan 2006
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Low Complexity Decoder for Space-Time Turbo Codes
Lee Chang-Woo ;
The Journal of Korean Institute of Communications and Information Sciences, volume 31, issue 4C, 2006, Pages 303~309
By combining the space-time diversity technique and iterative turbo codes, space-time turbo codes(STTCS) are able to provide powerful error correction capability. However, the multi-path transmission and iterative decoding structure of STTCS make the decoder very complex. In this paper, we propose a low complexity decoder, which can be used to decode STTCS as well as general iterative codes such as turbo codes. The efficient implementation of the backward recursion and the log-likelihood ratio(LLR) update in the proposed algorithm improves the computational efficiency. In addition, if we approximate the calculation of the joint LLR by using the approximate ratio(AR) algorithm, the computational complexity can be reduced even further. A complexity analysis and computer simulations over the Rayleigh fading channel show that the proposed algorithm necessitates less than 40% of the additions required by the conventional Max-Log-MAP algorithm, while providing the same overall performance.
New Message-Passing Decoding Algorithm of LDPC Codes by Partitioning Check Nodes
Kim Sung-Hwan ; Jang Min-Ho ; No Jong-Seon ; Hong Song-Nam ; Shin Dong-Joon ;
The Journal of Korean Institute of Communications and Information Sciences, volume 31, issue 4C, 2006, Pages 310~317
In this paper, we propose a new sequential message-passing decoding algorithm of low-density parity-check (LDPC) codes by partitioning check nodes. This new decoding algorithm shows better bit error rate(BER) performance than that of the conventional message-passing decoding algorithm, especially for small number of iterations. Analytical results tell us that as the number of partitioned subsets of check nodes increases, the BER performance becomes better. We also derive the recursive equations for mean values of messages at variable nodes by using density evolution with Gaussian approximation. Simulation results also confirm the analytical results.
Short and Efficient Frequency Hopping Codes
Kim Young-Joon ; Kim Dae-Son ; Song Hong-Yeop ;
The Journal of Korean Institute of Communications and Information Sciences, volume 31, issue 4C, 2006, Pages 318~323
In this paper we propose three methods to generate short hopping sequences for the frequency hopping system. First, we explain the one coincidence set of sequences and the polyphase power residue seqences which have been known previously, and we suggest a method by modifying the one coincidence sequence and two methods by using the power residue sequences. We verify that the optimal position deleted-power residue sequences have the best Hamming autocorrelation property and the first position deleted-power residue sequences and the modified one coincidence sequences follows with respect to Hamming autocorrelation. We also explain that these sequences have the good balance property and can be implemented with low complexity.
Analysis of Rate-Compatible Punctured Serial Concatenated Convolutional Codes Based on SNR Evolution
Shin Seung-Kyu ; Shin Dong-Joon ;
The Journal of Korean Institute of Communications and Information Sciences, volume 31, issue 4C, 2006, Pages 324~330
The next generation mobile communication systems require error correcting schemes that can be adaptable to various code rates and lengths with negligible performance degradation. Serial concatenated convolutional codes can be a good candidate satisfying these requirements. In this paper, we propose new rate-compatible punctured serial concatenated convolutional code (RCPSCCC) which performs better than the RCPSCCC proposed by Chandran and Valenti in the sense of the rate compatibility. These codes are evaluated and analyzed by using computer simulation and SNR evolution technique. As their application, Type-II hybrid automatic repeat request (HARQ) schemes using both RCPSCCCs are constructed and new RCPSCCC is shown to have better throughput.
A Rapid Signal Acquisition Scheme for Noncoherent UWB Systems
Kim Jae-Woon ; Yang Suck-Chel ; Choi Sung-Soo ; Shin Yo-An ;
The Journal of Korean Institute of Communications and Information Sciences, volume 31, issue 4C, 2006, Pages 331~340
In this Paper, we propose to extend the TSS-LS(Two-Step Search scheme with Linear search based Second step) scheme which was already proposed by the authors for coherent UWB(Ultra Wide Band) systems, to rapid and reliable acquisition of noncoherent UWB systems in multipath channels. The proposed noncoherent TSS-LS employing simple energy window banks utilizes two different thresholds and search windows to achieve fast acquisition. Furthermore, the linear search is adopted for the second step in the proposed scheme to correctly find the starting point in the range of effective delay spread of the multipath channels, and to obtain reliable BER(Bit Error Rate) performance of the noncoherent UWB systems. Simulation results with multipath channel models by IEEE 802.15.3a show that the proposed two-step search scheme can achieve significant reduction of the required mean acquisition time as compared to general search schemes. ]n addition, the proposed scheme achieves quite good BER performance for large signal-to-noise ratios, which is favorably comparable to the case of ideal perfect timing.
Virtual Tactical Map : Military Briefing Tools for Virtual Training based on Augmented Reality
Jung Kyung-Boo ; Lee Sang-Won ; Choi Byung-Uk ; Jeong Seung-Do ;
The Journal of Korean Institute of Communications and Information Sciences, volume 31, issue 4C, 2006, Pages 341~350
The sand table training is one of the most effective training method in military operations which can accomplish missions such as simulation and rehearsal without limitations related to time, space, money and so on. Previous sand table training has many problems like that the sand table cannot represent real field condition because of its physical properties. So, it is hard to be preserved and impossible to include much of information into them. In this paper, we make an approach based on Augmented Reality(AR) to solve these problems and propose an efficient military training briefing tool with virtual sand table environment described as actual battle field Virtual Tactical Map(VTM) can realize a virtual military training with simple action like moving marker or tangible interface by hand. Real-time state information of VTM gives us more organic intelligence for entire situation. Tangible AR interface provides users with a contents authoring tool that is natural, intuitive and easy to deal with as interaction between user in real world and system that augmented real world with virtual object. VTM is a newly designed military training briefing tools. A military training content can be reproduced and it is possible that user uses this content later. Thus, it shows us potential possibilities of AR applications on military leaning field.
Performance Improvement of Terrestrial DTV Receivers Using Frequency-domain Equalization
Son Sang-Won ; Kim Ji-Hyun ; Kim Hyoung-Nam ;
The Journal of Korean Institute of Communications and Information Sciences, volume 31, issue 4C, 2006, Pages 351~363
The 8-VSB modulation, the transmission standard for the terrestrial digital television(DTV) of the Advanced Television Systems Committee(ATSC), suffers from multipath fading because it conveys information on the amplitude. To solve this problem, decision feedback equalizers(DFE's) have been commonly used in terrestrial DTV receivers. However, under severe channels, such as a 0 dB ghost channel or a single frequency network (SFN) channel, the DFE shows unstable convergence due to the error propagation caused by decision errors. Instead of unstable time-domain DFE schemes, by proposing a frequency-domain direct-inversion equalization method, we try to guarantee stable equalization and achieve low symbol error rates. To secure the existence of a channel inverse, channel-matched filtering and noncausal filtering are carried out prior to equalization. Simulation results show that the proposed method performs much better than existing DFE schemes in terms of both the stability and the symbol error rate.
Estimation of Frequency Offset in TDMA-Based Satellite Systems
Kim Jong-Moon ; Lee Yong-Hwan ;
The Journal of Korean Institute of Communications and Information Sciences, volume 31, issue 4C, 2006, Pages 364~370
It is required for correct signal detection to accurately maintain the synchronization of frequency and timing in a TDMA system. In this paper, we consider nondecision-aided estimation of frequency offset for the transmission of QPSK signal in a TDMA-based satellite system. The proposed scheme estimates the phases of two parts in the burst and then estimates the frequency offset based on the difference between the two estimated phases. Thus, it can provides performance comparable to that of conventional schemes, while significantly reducing the implementation complexity, The performance of the proposed scheme is analyzed and verified by computer simulation, when applied to a GSM based geostationary earth orbit mobile radio(GMR) system.
Code Acquisition with Receive Diversity and Constant False Alarm Rate Schemes: 1. Homogeneous Fading Circumstance
Kwon Hyoung-Moon ; Oh Jong-Ho ; Song Iick-Ho ; Lee Ju-Mi ;
The Journal of Korean Institute of Communications and Information Sciences, volume 31, issue 4C, 2006, Pages 371~380
The performance characteristics of the cell averaging(CA), greatest of(GO), and smallest of(SO) constant false alarm rate(CFAR) processors in homogeneous environment are obtained and compared when receiving antenna diversity is employed in the pseudonoise code acquisition of direct-sequence code division multiple access (DS/CDMA) systems. From the simulation results, it is observed that the CA CFAR scheme has the best performance and the GO CFAR scheme has almost the same performance as the CA CFAR scheme in homogeneous environment. In Part 2 of this paper, the CA, GO, and SO CFAR processors for code acquisition in nonhomogeneous environment are addressed.
3D Reconstruction Using the Planar Homograpy
Yoon Yong-In ; Ohk Hyung-Soo ; Choi Jong-Soo ; Oh Jeong-Su ;
The Journal of Korean Institute of Communications and Information Sciences, volume 31, issue 4C, 2006, Pages 381~390
This paper proposes a new technque of the camera calibration to be computed a homography between the planar patterns taken by a single image to be located at the three planar patterns from uncalibrated images. It is essential to calibrate a camera for 3-dimensional reconstruction from uncalibrated image. Since the proposed method should be computed from the homography among the three planar patterns from a single image, it is implemented to more easily and simply to recover 3D reconstruction of an object than the conventional. Experimental results show the performances of the proposed method are the better than the conventional. We demonstrate examples of recovering 3D reconstruction using the proposed algorithm from uncalibrated images.
Adaptive Irregular Binning and Its Application to Video Coding Scheme Using Iterative Decoding
Choi Kang-Sun ;
The Journal of Korean Institute of Communications and Information Sciences, volume 31, issue 4C, 2006, Pages 391~399
We propose a novel low complexity video encoder, at the expense of a complex decoder, where video frames are intra-coded periodically and frames in between successive intra-coded frames are coded efficiently using a proposed irregular binning technique. We investigate a method of forming an irregular binning which is capable of quantizing any value effectively with only small number of bins, by exploiting the correlation between successive frames. This correlation is additionally exploited at the decoder, where the quality of reconstructed frames is enhanced gradually by applying POCS(projection on the convex sets). After an image frame is reconstructed with the irregular binning information at the proposed decoder, we can further improve the resulting quality by modifying the reconstructed image with motion-compensated image components from the neighboring frames which are considered to contain image details. In the proposed decoder, several iterations of these modification and re-projection steps can be invoked. Experimental results show that the performance of the proposed coding scheme is comparable to that of H.264/AVC coding in m mode. Since the proposed video coding does not require motion estimation at the encoder, it can be considered as an alternative for some versions of H.264/AVC in applications requiring a simple encoder.
Impact of Feature Positions on Focal Length Estimation of Self-Calibration
Hong Yoo-Jung ; Lee Byung-Uk ;
The Journal of Korean Institute of Communications and Information Sciences, volume 31, issue 4C, 2006, Pages 400~406
Knowledge of camera parameters, such as position, orientation and focal length, is essential to 3D information recovery or virtual object insertion. This paper analyzes the error sensitivity of focal length due to position error of feature points which are employed for self-calibration. We verify the dependency of the focal length on the distance from the principal point to feature points with simulations, and propose a criterion for feature selection to reduce the error sensitivity.
A Study on Motion Detection of Object Using Active Block Matching Algorithm
Lee Chang-Soo ; Park Mi-Og ; Lee Kyung-Seok ;
The Journal of Korean Institute of Communications and Information Sciences, volume 31, issue 4C, 2006, Pages 407~416
It is difficult for the movement detection of an object through a camera to detect exact movement because of unnecessary noises and changes of the light. It can be recognized as a background, when there is no movement after the inflow of an object. Therefore, It is necessary to fast search algorithm for tracking and extract of object that is realtime image. In this thesis, we evaluate the difference of the input vision based on initial image and replace some pixels in process of time. When there is a big difference between background image and input image, we decide it is the point of the time of the object input and then extract boundary point of it. The extracted boundary point detects precise movement of the object by creating minimum block of it and searching block that maintaining distance. The designed and embodied system shows more than 95% accuracy in the performance test.
Fast Panoramic Video Generation Method Using Morphological Corner Detection
Lee Jung-Ho ; Lee Kwan-Su ; Yang Won-Keun ; Jin Joo-Kyung ; Jeong Dong-Seok ;
The Journal of Korean Institute of Communications and Information Sciences, volume 31, issue 4C, 2006, Pages 417~425
This Paper Proposes a method of building a panoramic video from several videos captured from adjacent cameras. The panoramic image which constructed from adjacent and overlapped images is used for photogrammetry, satellite photo or many computer graphic applications. The perspective transformation, which is estimated from the appropriate corresponding pairs of images, can be used to construct the panoramic image without unwarranted distortion and its quality is decided by how to find the features needed for transform estimation. We used the corner points for the corresponding features, and morphological structures were utilized for fast and robust corner detection. We used the criterion of the corner strength, which guarantees the robust detection of the corner in most situations. For the transformation, 8 parameters were estimated from perspective equations which use matched points of adjacent images, and bilinear color blending was used to construct a soapless panoramic video. The experiments showed that the proposed method yields fast results with good quality under various conditions.
Double Binary Turbo hybrid ARQ Scheme
Kwon Woo-Suk ; Lee Jeong-Woo ;
The Journal of Korean Institute of Communications and Information Sciences, volume 31, issue 4C, 2006, Pages 426~433
In this paper, we propose an incremental redundancy(IR)-hybrid ARQ(HARQ) scheme which uses double binary turbo codes for error correction. We also propose a methodology for basic analysis of the throughput which is a performance index of HARQ. The proposed double binary turbo IR-HARQ scheme provides higher throughput than binary IR-HARQ, which uses binary turbo codes for error correction, at all
. An extra coding gain is also attained by using the proposed HARQ scheme over the coding gain achieved by turbo codes only.
Eigenvalues of Non-Sylvester Hadamard Matrices Constructed by Monomial Permutation Matrices
Lee Seung-Rae ; No Jong-Seon ; Sung Koeng-Mo ;
The Journal of Korean Institute of Communications and Information Sciences, volume 31, issue 4C, 2006, Pages 434~440
In this paper, the eigenvalues of various non-Sylvester Hadamard matrices constructed by monomial permutation matrices are derived, which shows the relation between the eigenvalues of the newly constructed matrix and Sylvester Hadamard matrix.
A Study on EAP-AKA Authentication Architecture for WiBro Wireless Network
Lim Sun-Hee ; Yi Ok-Yeon ; Jun Sung-Ik ; Han Jin-Hee ;
The Journal of Korean Institute of Communications and Information Sciences, volume 31, issue 4C, 2006, Pages 441~450
WiBro(Portable Internet Service) is service being capable to provide a high data rate wireless internet access with Personal Subscriber Station under the stationary or mobile environment, anytime and any where. It will fill the gap between very high data rate wireless local area networks and very high mobility cellular systems. The security is an important point of WiBro providing high data and mobile wireless services. This paper proposes user authentication mechanism of WiBro wireless networks applied EAP-AKA authentication protocol. As a result of Wireless authentication based on EAP-AKA, this mechanism is capable to be used in WiBro-WLAN-3GPP interworking scenario as well as the WiBro authentication mechanism.
Defending Against Some Active Attacks in P2P Overlay Networks
Park Jun-Cheol ;
The Journal of Korean Institute of Communications and Information Sciences, volume 31, issue 4C, 2006, Pages 451~457
A peer-to-peer(P2P) network is inherently vulnerable to malicious attacks from participating peers because of its open, flat, and autonomous nature. This paper addresses the problem of effectively defending from active attacks of malicious peers at bootstrapping phase and at online phase, respectively. We propose a secure membership handling protocol to protect the assignment of ID related things to a newly joining peer with the aid of a trusted entity in the network. The trusted entities are only consulted when new peers are joining and are otherwise uninvolved in the actions of the P2P networks. For the attacks in online phase, we present a novel message structure applied to each message transmitted on the P2P overlay. It facilitates the detection of message alteration, replay attack and a message with wrong information. Taken together, the proposed techniques deter malicious peers from cheating and encourage good peers to obey the protocol of the network. The techniques assume a basic P2P overlay network model, which is generic enough to encompass a large class of well-known P2P networks, either unstructured or not.
Watermarking of Compressed Video in the Bitstream Domain: An Efficient Algorithm and its Implementation
Drobouchevitvh Inna G. ; Lim Sung-Jun ; Han Byung-Wan ; Chang Hang-Bae ; Kim Kyung-Kyu ;
The Journal of Korean Institute of Communications and Information Sciences, volume 31, issue 4C, 2006, Pages 458~471
Digital watermarking of multimedia data is a very active research area that has enjoyed a considerable amount of attention in recent years. In this paper, we propose an algorithm for embedding/detecting a fragile watermark in MPEG-4 compressed video domain (Simple and Advance Simple Profiles). The watermark bits are put directly into Huffman VLC-codespace of quantized DCT domain. The advantage of watermark embedding into the compressed domain is the significant savings for a real-time implementation as it does not require a full decoding operation. The watermark embedding does not change the video file size. The algorithm demonstrates high watermarking capacity, thereby providing reliable foolproof authentication. The results of experimental testing demonstrate that watermark embedding preserves the video quality. Watermark detection is performed without using the original video.
Practical Improvement of An Efficient Public-Key framework and Its Application
Yang Jong-Phil ; Shin Weon ; Rhee Kyung-Hyune ;
The Journal of Korean Institute of Communications and Information Sciences, volume 31, issue 4C, 2006, Pages 472~481
J. Zhou et al. proposed a new public-key framewort in which the maximum lifetime of a certificate is divided into short periods and the certificate could be expired at the end of any period under the control of the certificate owner(or his manager in a corporate environment). However, J. Zhou et al.'s public-key framework is not suitable on implementation in real world. Therefore, we review some security Parameters to change them into more suitable ones for implementation and remove an unnecessary trust party of J. Zhou et al.'s public-key framework. Then, we propose an improved scheme for realistic solution. Moreover, we present a practical application based on the improved framework.