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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 37C, Issue 12 - Dec 2012
Volume 37B, Issue 12 - Dec 2012
Volume 37A, Issue 12 - Dec 2012
Volume 37C, Issue 11 - Nov 2012
Volume 37B, Issue 11 - Nov 2012
Volume 37A, Issue 11 - Nov 2012
Volume 37C, Issue 10 - Oct 2012
Volume 37B, Issue 10 - Oct 2012
Volume 37A, Issue 10 - Oct 2012
Volume 37C, Issue 9 - Sep 2012
Volume 37B, Issue 9 - Sep 2012
Volume 37A, Issue 9 - Sep 2012
Volume 37, Issue 8C - Aug 2012
Volume 37, Issue 8B - Aug 2012
Volume 37, Issue 8A - Aug 2012
Volume 37, Issue 7C - Jul 2012
Volume 37, Issue 7B - Jul 2012
Volume 37, Issue 7A - Jul 2012
Volume 37, Issue 6C - Jun 2012
Volume 37, Issue 6B - Jun 2012
Volume 37, Issue 6A - Jun 2012
Volume 37, Issue 5C - May 2012
Volume 37, Issue 5B - May 2012
Volume 37, Issue 5A - May 2012
Volume 37, Issue 4C - Apr 2012
Volume 37, Issue 4B - Apr 2012
Volume 37, Issue 4A - Apr 2012
Volume 37, Issue 3C - Mar 2012
Volume 37, Issue 3B - Mar 2012
Volume 37, Issue 3A - Mar 2012
Volume 37, Issue 2C - Feb 2012
Volume 37, Issue 2B - Feb 2012
Volume 37, Issue 2A - Feb 2012
Volume 37, Issue 1C - Jan 2012
Volume 37, Issue 1B - Jan 2012
Volume 37, Issue 1A - Jan 2012
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Implementation of an Efficient Slotted CSMA/CA Anti-collision Protocol for Active RFID System
Joo, Jin-Hoon ; Chung, Sang-Hwa ;
The Journal of Korean Institute of Communications and Information Sciences, volume 37A, issue 12, 2012, Pages 1013~1022
DOI : 10.7840/kics.2012.37A.12.1013
Tag collection is one of the major concerns in radio frequency identification(RFID) system. All tags in RFID reader's transmission range send response message back to the reader in response to collection request message on the given rf channel. When multiple tags respond simultaneously, tag-collision may occur. Tag-collision problem is one of the most important issues in active RFID performance. To mitigate this problem, frame slotted ALOHA(FSA) anti-collision protocol is widely used in active RFID system. Several studies show that the maximum system efficiency of FSA anti-collision protocol is 36.8%. In this paper, we propose an efficient slotted CSMA/CA protocol to improve tag collection performance. We compare our protocol to the FSA anti-collision protocol. For the experiment, an 433MHz active RFID system is implemented, which is composed of an RFID reader and multiple tags. We evaluated the tag collection performance using one RFID reader and 40 tags in the real test bed. The experimental result shows that proposed protocol improves the tag collection time, round and collision probability by 18%, 37.4% and 77.8%, respectively.
Analysis on the Correlation Coefficient for the Diversity Technique Combined with Beamforming Using Measurement Data in Underwater Channel Environments
Kim, Min-Sang ; Cho, Dae-Young ; Park, Jong-Won ; Lim, Yong-Kon ; Ko, Hak-Lim ;
The Journal of Korean Institute of Communications and Information Sciences, volume 37A, issue 12, 2012, Pages 1023~1030
DOI : 10.7840/kics.2012.37A.12.1023
The diversity techniques can benefit underwater acoustic communications when the distance between sensors is sufficiently apart, and this leads to the increases in the physical size of the communication system: thus it is very hard to practically use such systems in real-environments. Therefore, in this paper, we have collected data from real underwater cannel environments in order to analyze the usability of diversity combined with beamforming techniques. And we have estimated the fading characteristics from the measurement data, and analyzed the correlation coefficients using the estimated fading characteristics. After analyzing the estimated fading characteristics from the measurements data, we found out that by applying diversity techniques on the output signals from beamformers that perform beamforming from different multipath directions, we can reduce the distance between sensors and at the same time benefit from the diversity gain.
Square and Cube Root Algorithms in Finite Field and Their Applications
Cho, Gook Hwa ; Ha, Eunhye ; Koo, Namhun ; Kwon, Soonhak ;
The Journal of Korean Institute of Communications and Information Sciences, volume 37A, issue 12, 2012, Pages 1031~1037
DOI : 10.7840/kics.2012.37A.12.1031
We study an algorithm that can efficiently find square roots and cube roots by modifying Tonelli-Shanks algorithm, which has an application in Number Field Sieve (NFS). The Number Field Sieve, the fastest known factoring algorithm, is a powerful tool for factoring very large integer. NFS first chooses two polynomials having common root modulo N, and it consists of the following four major steps; 1. Polynomial Selection 2. Sieving 3. Matrix 4. Square Root. The last step of NFS needs the process of square root computation in Number Field, which can be computed via square root algorithm over finite field.
Distance Measure for Biased Probability Density Functions and Related Equalizer Algorithms for Non-Gaussian Noise
Kim, Namyong ;
The Journal of Korean Institute of Communications and Information Sciences, volume 37A, issue 12, 2012, Pages 1038~1042
DOI : 10.7840/kics.2012.37A.12.1038
In this paper, a new distance measure for biased PDFs is proposed and a related equalizer algorithm is also derived for supervised adaptive equalization for multipath channels with impulsive and time-varying DC bias noise. From the simulation results in the non-Gaussian noise environments, the proposed algorithm has proven not only robust to impulsive noise but also to have the capability of cancelling time-varying DC bias noise effectively.
Efficient Distributed Video Coding System without Feedback Channel
Moon, Hak-Soo ; Lee, Chang-Woo ; Lee, Seong-Won ;
The Journal of Korean Institute of Communications and Information Sciences, volume 37A, issue 12, 2012, Pages 1043~1053
DOI : 10.7840/kics.2012.37A.12.1043
In distributed video coding (DVC) systems, the complexity of encoders is greatly reduced by removing the motion estimation operations in encoders, since the correlation between frames is utilized in decoders. The transmission of parity bits is requested through the feedback channel, until the related errors are corrected to decode the Wyner-Ziv frames. The requirement to use the feedback channel limits the application of DVC systems. In this paper, we propose an efficient method to remove the feedback channel in DVC systems. First, a simple side information generation method is proposed to calculate the amount of parity bits in the encoder, and it is shown that the proposed method yields good performance with low complexity. Then, by calibrating the theoretical entropy with three parameters, we can calculate the amount of parity bits in the encoder and remove the feedback channel. Moreover, an adaptive method to determine quantization parameters for key frames is proposed. Extensive computer simulations show that the proposed method yields better performance than conventional methods.
Multi Scale Tone Mapping Model Using Visual Brightness Functions for HDR Image Compression
Kwon, Hyuk-Ju ; Lee, Sung-Hak ; Chae, Seok-Min ; Sohng, Kyu-Ik ;
The Journal of Korean Institute of Communications and Information Sciences, volume 37A, issue 12, 2012, Pages 1054~1064
DOI : 10.7840/kics.2012.37A.12.1054
HDR (high dynamic range) tone mapping algorithms are used in image processing that reduces the dynamic range of an image to be displayed on LDR (low dynamic range) devices properly. The retinex is one of the tone mapping algorithms to provide dynamic range compression, color constancy, and color rendition. It has been developed through multi-scale methods and luminance-based methods. Retinex algorithms still have drawbacks such as the emphasized noise and desaturation. In this paper, we propose a multi scale tone mapping algorithm for enhancement of contrast, saturation, and noise of HDR rendered images based on visual brightness functions. In the proposed algorithm, HSV color space has been used for preserving the hue and saturation of images. And the algorithm includes the estimation of minimum and maximum luminance level and a visual gamma function for the variation of viewing conditions. And subjective and objective evaluations show that proposed algorithm is better than existing algorithms. The proposed algorithm is expected to image quality enhancement in some fields that require a improvement of the dynamic range due to the changes in the viewing condition.
Improvement of the Link Reliability for Ship Ad-Hoc Network by Employing Multiple Antennas
Su, Xin ; Hui, Bing ; Chang, KyungHi ; Kim, SeungGeun ;
The Journal of Korean Institute of Communications and Information Sciences, volume 37A, issue 12, 2012, Pages 1065~1075
DOI : 10.7840/kics.2012.37A.12.1065
For the purpose of providing high data rate real-time services, radio transmission technologies (RTT) for ship ad-hoc network (SANET) based on the Recommendation ITU-R 1842-1 are designed. Physical layer parameters of SANET are contrived to meet the requirements of the specification. In order to improve the link reliability for SANET, in this paper, we investigate the performance of the SANET with the multiple antennas, where receive combining (RC), transmit diversity (TD), and beamforming (BF) are employed, respectively. Based on the analysis of the packet error rate (PER) under the highly correlated maritime wireless channel model, we select the efficient multiple antenna schemes for SANET to improve the link reliability. In addition, the optimal MCS levels for the single-carrier (SC) SANET with the bandwidth of 25 kHz, and the multi-carrier (MC) SANET with the bandwidth of 50 kHz and 100 kHz are finalized.
A Cell Selection Technique Considering MIMO Precoding
Kim, Han Seong ; Hong, Tae Howan ; Cho, Yong Soo ;
The Journal of Korean Institute of Communications and Information Sciences, volume 37A, issue 12, 2012, Pages 1076~1084
DOI : 10.7840/kics.2012.37A.12.1076
In the CS/CB(Coordinated Scheduling/Beamforming) scheme, the cell edge user throughput is increased by selecting MIMO (Multiple Input Multiple Output) precoders which can minimize the interferences from adjacent base stations (BSs). However, in current LTE(Long Term Evolution) systems, the serving cell is selected in the initialization stage by using the synchronization signals and cell specific reference signals transmitted by adjacent BSs with a single antenna. The selected BS in the initialization stage may not be the best one since the MIMO precoding gain has not been considered in the cell selection stage. In this paper, a new cell selection technique is proposed for LTE systems with MIMO precoder by taking into account the effect of the precoder in the initialization stage. The proposed technique enables a user equipment (UE) in the cell boundary to select the serving BS by using the information (channel rank, effective channel capacity, and effective SINR(Signal to Interference plus Noise Ratio)) acquired from cell specific reference signals of candidate BSs. It is verified by computer simulation that the proposed technique can increase the channel capacity significantly in the multi-cell environments, compared with the conventional CS/CB scheme.
Performance Analysis of Tradeoff between Energy Consumption and Activation Delay in UMTS State Transition Mechanism
Choi, Hyun-Ho ;
The Journal of Korean Institute of Communications and Information Sciences, volume 37A, issue 12, 2012, Pages 1085~1092
DOI : 10.7840/kics.2012.37A.12.1085
Mobile communication systems define user state transition mechanisms in order to manage radio resources and battery power efficiently. In the state transition mechanism, a state with a higher energy consumption inherently offers a shorter access delay, so there is a tradeoff between the energy and delay performances. In this paper, we analyze the user state transition mechanism of UMTS by considering the bursty traffic attributes of mobile applications. We perform a numerical evaluation for both the energy consumption and the activation delay by Markov modeling of the state transition mechanism, and investigate their tradeoff relationship as functions of operational parameters. The resulting energy-delay tradeoff curves clearly show an achievable performance bound of the user state transition mechanism and also offer an optimal operation strategy to minimize the energy consumption while guaranteeing the delay requirement.
Interference Space Reuse and the Adoption Strategy through QoS Constraints in Three-Cell Downlink MIMO Interference Channels
Yoon, Jangho ; Lee, Hwang Soo ;
The Journal of Korean Institute of Communications and Information Sciences, volume 37A, issue 12, 2012, Pages 1093~1105
DOI : 10.7840/kics.2012.37A.12.1093
We propose an interference space reuse (ISR) algorithm for the MU-MIMO design in 3-cell downlink interference channels. Also, we provide a strategy for the adoption of the ISR scheme in the cellular network. In the multicell interference channels, the cell edge users may undergo severe interferences and their signals should be protected from the interferers for reliable transmissions. However, the intra cell users do not only experience small interferences but also they require small transmission power for stable communication. We provide a vector design algorithm based on ISR, where intra cell users are served through reusing the cell edge users' interference space. The performance enhancement reaches 20% compared to the fractional frequency reuse (FFR) scheme combined with IA through the scheduling between the cell edge users and the intra cell users. Also, it can be used to enhance the cell edge throughput when the quality of service (QoS) requirements of the intra cell users are fixed.
Application of 3GPP LTE and IEEE 802.11p Systems to Ship Ad-Hoc Network with the Existence of ISI
Su, Xin ; Hui, Bing ; Chang, KyungHi ; Jin, Gwangja ;
The Journal of Korean Institute of Communications and Information Sciences, volume 37A, issue 12, 2012, Pages 1106~1114
DOI : 10.7840/kics.2012.37A.12.1106
In order to provide high data rate and real time services under maritime environment, link-level performance of ship ad-hoc network (SANET) based on 3GPP LTE and IEEE 802.11p (WAVE) specifications are investigated and discussed in this paper. The measured maritime channel, whose delay spread is longer than the length of guard interval (GI) of both 3GPP LTE and IEEE 802.11p specifications, is adopted for the link-level simulations. For the purpose of eliminating inter-symbol interference (ISI) due to insufficient GI length, double antenna pattern (DAP) scheme and advanced time-domain decision-feedback equalizer (DFE) are proposed for LTE and WAVE systems, respectively. The proposed DFE removes the ISI in a same manner as the residual inter-symbol interference cancellation (RISIC) algorithm, but the inter-carrier interference (ICI) is reduced via cyclicity removal instead of cyclicity restoration used in the RISIC algorithm. Compared with existing schemes, our proposed DFE is a robust technique to overcome the severe ISI channel which has a comparatively large delay spread. Based on simulation results, not only comparisons between systems are discussed, but also some reformative suggestions are given.
Design of UTP LAN Cable With Enhanced Alien Crosstalk Characteristic
Kim, June-Hyong ; Lee, Seong-Jun ; Oh, Sung-Ki ;
The Journal of Korean Institute of Communications and Information Sciences, volume 37A, issue 12, 2012, Pages 1115~1121
DOI : 10.7840/kics.2012.37A.12.1115
In this paper, the design of UTP LAN cable with enhanced alien crosstalk characteristic is proposed. Proposed LAN cable is made with jacket of the irregularly corrugation type. If necessary, it is possible to use the special cross-filler. The alien crosstalk characteristic is enhanced by using proposed cable with inner jacket of the irregularly corrugation type in wide frequency band. The design of the cable was based on parameters of the standard EIA/TIA 568-B.2-10.
A Study on the Reconstruction of a Frame Based Speech Signal through Dictionary Learning and Adaptive Compressed Sensing
Jeong, Seongmoon ; Lim, Dongmin ;
The Journal of Korean Institute of Communications and Information Sciences, volume 37A, issue 12, 2012, Pages 1122~1132
DOI : 10.7840/kics.2012.37A.12.1122
Compressed sensing has been applied to many fields such as images, speech signals, radars, etc. It has been mainly applied to stationary signals, and reconstruction error could grow as compression ratios are increased by decreasing measurements. To resolve the problem, speech signals are divided into frames and processed in parallel. The frames are made sparse by dictionary learning, and adaptive compressed sensing is applied which designs the compressed sensing reconstruction matrix adaptively by using the difference between the sparse coefficient vector and its reconstruction. Through the proposed method, we could see that fast and accurate reconstruction of non-stationary signals is possible with compressed sensing.
On The Performance of a Hybrid Mode Beamforming in A Two-Cell System
Yang, Janghoon ; Chae, Hyukjin ; Kim, Dong Ku ;
The Journal of Korean Institute of Communications and Information Sciences, volume 37A, issue 12, 2012, Pages 1133~1139
DOI : 10.7840/kics.2012.37A.12.1133
In this paper, hybrid mode beamforming (HMB) which allows simultaneous transmission of joint beamforming and disjoint beamforming is proposed. HMB is proven to be asymptotically optimal beamforming for sum rate growth. Extensive simulations show that HMB achieves nearly the same performance as joint encoding (JE) in symmetric interference channel. It is also shown that it outperforms JE in a more realistic asymmetric interference channel environment, though it still experiences some performance degradation due to power inefficiency of joint beamforming in asymmetric channel.
A Timing Offset Estimation Scheme Based on Cross-Correlation Accumulation for Initial Ranging of IEEE 802.16e Systems
Lee, Jaewoo ; Yoon, Seokho ;
The Journal of Korean Institute of Communications and Information Sciences, volume 37A, issue 12, 2012, Pages 1140~1144
DOI : 10.7840/kics.2012.37A.12.1140
In this paper, we propose a timing offset estimation scheme for initial ranging of IEEE 802.16e systems. The conventional scheme estimates the timing offset by using the cross-correlation between the local and received signals only. On the other hand, this paper proposes a timing offset estimation scheme with additional cross-correlations accumulated on the conventional cross-correlation. The additional cross-correlations are obtained by using the ranging signal with a repetitive structure. Numerical results show that the proposed scheme provides the better timing offset estimation performance compared with that of the conventional scheme.
A Novel Narrow Width BOC Correlation Function for BOC Signal Tracking
Lee, Youngseok ; Yoon, Seokho ;
The Journal of Korean Institute of Communications and Information Sciences, volume 37A, issue 12, 2012, Pages 1145~1151
DOI : 10.7840/kics.2012.37A.12.1145
In this paper, we propose an unambiguous binary offset carrier (BOC) correlation function with narrow main-peak width for BOC code tracking. Specifically, we first separate a subcarrier pulse into two rectangular pulses, obtain the associated partial correlations, and re-combine the partial correlations to yield the unambiguous correlation function with narrow main-peak width. From numerical results, it is demonstrated that the proposed correlation function provides a significant performance improvement over the conventional correlation functions.