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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 38C, Issue 12 - Dec 2013
Volume 38B, Issue 12 - Dec 2013
Volume 38A, Issue 12 - Dec 2013
Volume 38C, Issue 11 - Nov 2013
Volume 38B, Issue 11 - Nov 2013
Volume 38A, Issue 11 - Nov 2013
Volume 38C, Issue 10 - Oct 2013
Volume 38B, Issue 10 - Oct 2013
Volume 38A, Issue 10 - Oct 2013
Volume 38C, Issue 9 - Sep 2013
Volume 38B, Issue 9 - Sep 2013
Volume 38A, Issue 9 - Sep 2013
Volume 38C, Issue 8 - Aug 2013
Volume 38B, Issue 8 - Aug 2013
Volume 38A, Issue 8 - Aug 2013
Volume 38C, Issue 7 - Jul 2013
Volume 38B, Issue 7 - Jul 2013
Volume 38A, Issue 7 - Jul 2013
Volume 38C, Issue 6 - Jun 2013
Volume 38B, Issue 6 - Jun 2013
Volume 38A, Issue 6 - Jun 2013
Volume 38C, Issue 5 - May 2013
Volume 38B, Issue 5 - May 2013
Volume 38A, Issue 5 - May 2013
Volume 38C, Issue 4 - Apr 2013
Volume 38B, Issue 4 - Apr 2013
Volume 38A, Issue 4 - Apr 2013
Volume 38C, Issue 3 - Mar 2013
Volume 38B, Issue 3 - Mar 2013
Volume 38A, Issue 3 - Mar 2013
Volume 38C, Issue 2 - Feb 2013
Volume 38B, Issue 2 - Feb 2013
Volume 38A, Issue 2 - Feb 2013
Volume 38C, Issue 1 - Jan 2013
Volume 38B, Issue 1 - Jan 2013
Volume 38A, Issue 1 - Jan 2013
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Signal analysis of Hangul shaped Chipless RFID Tag
Ryu, Beongju ; Lee, Jehun ; Koh, Jinhwan ;
The Journal of Korean Institute of Communications and Information Sciences, volume 38A, issue 12, 2013, Pages 983~990
DOI : 10.7840/kics.2013.38A.12.983
In this paper, we proposed a Hangul type chipless RFID tag, which has better legibility than the conventional chipless RFID tag not only to a computer but also to a human. We made consonant model, vowel model and whole character model by WIPL tool and checked the applicability of Hangul type chipless RFID tag. We obtain the RCS pattern of each character by simulation. Finally, We classify the character from input data in noisy environment using a variance of the data.
Integrated Filter Circuits Design for Mobile Communications
Lee, Kwang ;
The Journal of Korean Institute of Communications and Information Sciences, volume 38A, issue 12, 2013, Pages 991~997
DOI : 10.7840/kics.2013.38A.12.991
A new frequency tuning scheme and a transconductor with a wide tuning range and low harmonic distortion is presented. This frequency tuning technique is based on the relationship between the time-constant and the elapsed times in charging a capacitor up to a certain level. Its structure is as simple as that of a conventional tuning scheme using a VCF(Voltage-Controlled Filter) and it does not need a pure sine wave but uses a CLK(Clock) pulse as a reference signal, which is easily obtained from on-chip system clocks or external X-tal oscillators. When a certain reference CLK is given, without complex capacitor arrays the pole frequency of the filter can be controlled continuously in the frequency domain. Simulation results are presented to confirm the operation of the proposed approach.
Equalized Net Diffusion (END) for the Preservation of Fine Structures in PDE-based Image Restoration
Cha, Youngjoon ; Kim, Seongjai ;
The Journal of Korean Institute of Communications and Information Sciences, volume 38A, issue 12, 2013, Pages 998~1012
DOI : 10.7840/kics.2013.38A.12.998
The article is concerned with a mathematical modeling which can improve performances of PDE-based restoration models. Most PDE-based restoration models tend to lose fine structures due to certain degrees of nonphysical dissipation. Sources of such an undesirable dissipation are analyzed for total variation-based restoration models. Based on the analysis, the so-called equalized net diffusion (END) modeling is suggested in order for PDE-based restoration models to significantly reduce nonphysical dissipation. It has been numerically verified that the END-incorporated models can preserve and recover fine structures satisfactorily, outperforming the basic models for both quality and efficiency. Various numerical examples are shown to demonstrate effectiveness of the END modeling.
Eigen-Analysis Based Super-Resolution Time Delay Estimation Algorithms for Spread Spectrum Signals
Park, Hyung-Rae ; Shin, Joon-Ho ;
The Journal of Korean Institute of Communications and Information Sciences, volume 38A, issue 12, 2013, Pages 1013~1020
DOI : 10.7840/kics.2013.38A.12.1013
In this paper the super-resolution time delay estimation algorithms based on eigen-analysis are developed for spread spectrum signals along with their comparative performance analysis. First, we shall develop super-resolution time delay estimation algorithms using the representative eigen-analysis based AOA (angle-of-arrival) estimation algorithms such as MUSIC, Minimum-Norm, and ESPRIT, and apply them to the ISO/IEC 24730-2.1 real-time locating system (RTLS) employing a direct sequence spread spectrum (DS-SS) technique to compare their performances in RTLS environments. Simulation results illustrate that all the three algorithms can resolve multipath signals whose delay differences are even smaller than the Rayleigh resolution limit. Simulation results also show that MUSIC and Minimum-Norm provide a similar performance while ESPRIT is inferior to both algorithms in RTLS environments.
Wireless LAN Based Indoor Positioning Using Received Signal Fingerprint and Propagation Prediction Model
Kim, Hyunsu ; Bae, Jimin ; Choi, Jihoon ;
The Journal of Korean Institute of Communications and Information Sciences, volume 38A, issue 12, 2013, Pages 1021~1029
DOI : 10.7840/kics.2013.38A.12.1021
In this paper, we propose a new indoor location estimation method which combines the fingerprint technique with the propagation prediction model. The wireless LAN (WLAN) access points (APs) deployed indoors are divided into public APs and private APs. While the fingerprint method can be easily used to public APs usually installed in fixed location, it is difficult to apply the fingerprint scheme to private APs whose location can be freely changed. In the proposed approach, the accuracy of user location estimation is improved by simultaneously utilizing public and private APs. Specifically, the fingerprint method is used to the received signals from public APs and the propagation prediction model is employed to the signals from private APs. The performance of the proposed method is compared with that of conventional indoor location estimation schemes through measurements and numerical simulations in WLAN environments.
2N-Point FFT-Based Inter-Carrier Interference Cancellation Alamouti Coded OFDM Method for Distributed Antennas systems
Kim, Bong-Seok ; Choi, Kwonhue ;
The Journal of Korean Institute of Communications and Information Sciences, volume 38A, issue 12, 2013, Pages 1030~1038
DOI : 10.7840/kics.2013.38A.12.1030
The proposed Alamouti coded OFDM effectively cancels Inter Carrier Interference (ICI) due to frequency offset between distributed antennas. The conventional Alamouti coded OFDM schemes to mitigate ICI utilize N-point Inverse Fast Fourier Transform/Fast Fourier Transform (IFFT/FFT) operations for OFDM modulation and demodulation processes with total N subcarriers. However, the performance degrades because ICI is also repeated in N periods due to the property of N-point IFFT/FFT operation. In order to avoid this problem, null data are used at the subcarriers with large ICI and thus, data rate decreases. The proposed scheme employs 2N-point IFFT/FFT instead of N-point IFFT/FFT in order to increase sampling rate. By increasing sampling rate, the amount of interference significantly decreases because the period of ICI also increases. The proposed scheme increases the data rate and improves the performance by reducing amount of ICI and the number of null-data. Furthermore, the gain of the performance and data rate of the proposed scheme is significant with higher modulation such as 16-Quadarature Amplitude Modulation (QAM) or 64-QAM.
Multiple Frequency Offsets Cancellation Scheme Based on Alamouti Coded OFDM for Distributed Antenna Systems in Selective Fading Channel
Kim, Bong-Seok ; Choi, Kwonhue ;
The Journal of Korean Institute of Communications and Information Sciences, volume 38A, issue 12, 2013, Pages 1039~1044
DOI : 10.7840/kics.2013.38A.12.1039
We propose a cancellation algorithm based on Alamouti coded OFDM to mitigate ICI due to Frequency Offset (FO) between distributed antennas in the frequency selective fading channel. In the cancellation algorithm, the interference signal is estimated by using the initial detection symbol and then the estimated interference signal is subtracted from the received signal. As the accuracy of initial symbol increases, ICI cancellation becomes more significant. Therefore, the accuracy of the initial detection symbols is very important in the cancellation algorithm. The proposed scheme improves the accuracy of the initial detection symbol by employing an ICI self-cancellation scheme. The proposed cancellation scheme with only one iteration achieves better performance compared to the conventional cancellation schemes with many times iterations based on the conventional Alamouti coded OFDM.
Power-Saving Mechanism Considering Round-Trip Delay in LTE Systems
Choi, Hyun-Ho ;
The Journal of Korean Institute of Communications and Information Sciences, volume 38A, issue 12, 2013, Pages 1045~1053
DOI : 10.7840/kics.2013.38A.12.1045
In this paper, we propose a new power-saving mechanism (PSM) for Long-Term Evolution (LTE) systems by considering a round-trip delay between a user equipment (UE) and its correspondence node. The proposed PSM changes the order of the operational procedures of the legacy LTE PSM by taking the traffic arrival pattern suffering the round-trip delay into account. After modeling the round-trip delay, we numerically analyze the proposed PSM with respect to energy consumption and buffering delay. Then, we characterize these performances by employing a simple energy-delay tradeoff (EDT) curve according to the operational parameters. The resulting EDT curve clearly shows that the proposed PSM outperforms the legacy LTE PSM in terms of both the energy consumption and buffering delay.
Routing Algorithm of VANET for an Efficient Path Management in Urban Intersections
Cho, Sunghyun ; Kim, Seokwoo ;
The Journal of Korean Institute of Communications and Information Sciences, volume 38A, issue 12, 2013, Pages 1054~1060
DOI : 10.7840/kics.2013.38A.12.1054
This paper proposes a vehicle ad-hoc network (VANET) routing algorithm to reduce the probability of routing path discontinuity in urban intersections. In urban intersections, the vehicles may frequently change their moving directions. It can cause the disconnection of routing path and the increase of a packet transmission delay. In order to resolve this problem, the proposed routing algorithm exploits the information of moving directions in urban intersections. In this way, the proposed algorithm can reduce the probability of the local maximum which causes the increase of the number of routing hops and packet transmission delay. Simulation results show that the proposed algorithm can reduce the local maximum probability by 10% and increase the successful packet transmission ratio by 5% compared to the conventional VANET routing algorithms.
Design and Performance Evaluation of M×M MIMO Transmission in ESPAR Antenna
Bok, Junyeong ; Lee, Seung Hwan ; Ryu, Heung-Gyoon ;
The Journal of Korean Institute of Communications and Information Sciences, volume 38A, issue 12, 2013, Pages 1061~1068
DOI : 10.7840/kics.2013.38A.12.1061
In this paper, we propose a
beam-space multiple input multiple output (BS-MIMO) system using electronically steerable parasitic array radiator (ESPAR) antenna. Conventional MIMO method required multiple RF chains because it map the transmission signals onto multiple antennas. So, conventional MIMO system has high cost for design and high energy consumption at RF circuit. Also, It is difficult to use MIMO system in battery based mobile terminals with limited physical area. In order to solve these problems, BS-MIMO technique which map the data signal onto bases in beam space domain was proposed using ESPAR antenna with single RF chain. This paper, we design and analyze the performance of extended
BS-MIMO technique. Simulation results show that the proposed BS-MIMO system has similar BER performance compare to conventional MIMO scheme. Therefore, BS-MIMO system with single RF chain will has a low RF power consumption and low cost for RF hardware design as compared with conventional MIMO technique with multiple RF chains.
A Distributed Time Synchronization Technique for OFDMA-based Wireless Mesh Communication Systems Using Bio-inspired Algorithm
Kim, Mi-Jeong ; Lee, Yun-Jae ; Cho, Yong-Soo ;
The Journal of Korean Institute of Communications and Information Sciences, volume 38A, issue 12, 2013, Pages 1069~1078
DOI : 10.7840/kics.2013.38A.12.1069
In this paper, we propose a distributed time synchronization technique for OFDMA- based wireless mesh communication systems. The proposed technique employs the bio-inspired algorithm for self-time synchronization in the physical layer. To achieve the network synchronicity, the proposed technique updates the transmission time and the FFT window using the TDoA information of received signals from the neighbor nodes. The proposed technique can achieve fast self-synchronization among nodes with a simple algorithm, without the need of a centralized controller. The performance of the proposed time synchronization technique is evaluated by simulation in terms of convergence speed and convergence probability.
A Variable Sample Rate Recursive Arithmetic Half Band Filter for SDR-based Digital Satellite Transponders
Baek, Dae-Sung ; Lim, Won-Gyu ; Kim, Chong-Hoon ;
The Journal of Korean Institute of Communications and Information Sciences, volume 38A, issue 12, 2013, Pages 1079~1085
DOI : 10.7840/kics.2013.38A.12.1079
Due to the limited power supply resources, it is essential that the minimization of algorithmic operation and the reduction of the hardware logical-resources in the design of the satellite transponder. It is also required that the transponder process the signals of various bandwidth efficiently, that is suitble for the SDR-based implementation. This paper proposes a variable rate down sampler which can provide variable bandwidth and data rate for carrier, ranging and sub-band command signals respectively. The proposed down sampler can provide multiple
decimated outputs from a single half band filter with recursive arithmetic architecture, which can minimize the hardware resources as well as the arithmetic operations. The algorithm for hardware implementation as well as the analysis for the passband flatness and aliasing is presented and varified by the FPGA implementation.
Subcarrier Intensity Modulation-Spatial Modulation for Optical Wireless Communications
Cheng, Yan ; Hwang, Seung-Hoon ;
The Journal of Korean Institute of Communications and Information Sciences, volume 38A, issue 12, 2013, Pages 1086~1093
DOI : 10.7840/kics.2013.38A.12.1086
In this paper, we propose a novel modulation that combines the spatial modulation (SM) with the subcarrier intensity-modulation (SIM) for optical wireless communications. The performance of SIM-SM scheme is compared to a conventional SIM by computer simulation. For the spectral efficiency (SE) of 2bits/s/Hz, the performance gain about 2dB is achieved. As the SE increases to 3bit or 4bits/s/Hz, the Eb/N0 gain becomes about 5dB. It is shown the attenuation for the SIM is more serious than the SIM-SM according to increasing the number of the subcarriers.
An Improved Dynamic Branch Predictor by Selective Access of a Specific Element in 4-Way Cache
Hwang, In-Sung ; Hwang, Sun-Young ;
The Journal of Korean Institute of Communications and Information Sciences, volume 38A, issue 12, 2013, Pages 1094~1101
DOI : 10.7840/kics.2013.38A.12.1094
This paper proposes an improved branch predictor that reduces the number execution cycles of applications by selectively accessing a specific element in 4-way associative cache. When a branch instruction is fetched, the proposed branch predictor acquires a branch target address from the selected element in the cache by referring to MRU buffer. Branch prediction rate and application execution speed are considerably improved by increasing the number of BTAC entries in restricted power condition, when compared with that of previous branch predictor which accesses all elements. The effectiveness of the proposed dynamic branch predictor is verified by executing benchmark applications on the core simulator. Experimental results show that number of execution cycles decreases by an average of 10.1%, while power consumption increases an average of 7.4%, when compared to that of a core without a dynamic branch predictor. Execution cycles are reduced by 4.1% in comparison with a core which employs previous dynamic branch predictor.
Dual-mode Transmission Strategy for Blind Interference Alignment Scheme in MISO Broadcast Channels
Yang, Minho ; Jang, Jinyoung ; Kim, Dong Ku ;
The Journal of Korean Institute of Communications and Information Sciences, volume 38A, issue 12, 2013, Pages 1102~1109
DOI : 10.7840/kics.2013.38A.12.1102
Blind interference alignment (BIA) scheme has demonstrated a way of interference alignment (IA) without channel state information at transmitter (CSIT). While it shows superior performance in high signal-to-noise ratio (SNR) regime stemming from the maximal degrees of freedom (DoF) gain, BIA scheme achieves inferior sum-rate performance in low SNR regime. This paper proposes a dual-mode transmission strategy which switches between single user (SU) SISO with receive mode selection and the BIA scheme depending upon the range of SNR. First, we derive a closed-form achievable rate for each transmission-mode. Secondly, we propose a low-complex transmission-mode selection algorithm.
A Novel Performance Evaluation Methodology for Small Cell Networks
Lim, Yeon-Geun ; Chae, Chan-Byoung ;
The Journal of Korean Institute of Communications and Information Sciences, volume 38A, issue 12, 2013, Pages 1110~1116
DOI : 10.7840/kics.2013.38A.12.1110
A 3D-ray tracing tool is a software considering reflection, penetration, and diffraction of the signals to provide accuracy. To provide communication resources effectively, communication standards adopt Heterogeneous Networks (HetNets) that includes small cells. A 3D performance evaluation methodology becomes more and more important since the coverage of the small cell networks is narrower than that of the macro cell networks. It is difficult to directly apply conventional 2D mathematical models due to the complexity of small cell network; since they have many considerations such as topography, placement of buildings and 3D beamforming techniques. In this paper, we introduce an effective performance evaluation methodology for small cell networks using 3D-ray tracing tool. From simulation results, we conclude that new performance evaluation methodologies by using 3D-ray tracing tool is more suitable than conventional methodology for small cell networks.
Interference Neutralization for Small-Cell Wireless Networks
Jeon, Sang-Woon ; Jung, Bang Chul ;
The Journal of Korean Institute of Communications and Information Sciences, volume 38A, issue 12, 2013, Pages 1117~1124
DOI : 10.7840/kics.2013.38A.12.1117
As the recently soaring wireless traffic, small-cell techniques have been actively studied in order to support such a wireless demand for cellular wireless networks. This paper focuses on the inter-cell interference neutralization to resolve the main barrier for implementing small-cell cellular networks. Assuming that each message is delivered to the final destination by the help of base stations or relays, ergodic interference neutralization is proposed, which exploits the time-varying nature of wireless channels. The previous approach based on amplify-and-forward (AF) suffers from severe performance degradation in the low signal-to-noise (SNR) regime due to noise amplification. On the other hand, the proposed interference neutralization based on recently developed compute-and-forward (CF) fixes such a problem and improves the performance in the low SNR regime.
Distributed BS Transmit Power Control for Utility Maximization in Small-Cell Networks
Lee, Changsik ; Kim, Jihwan ; Kwak, Jeongho ; Kim, Eunkyung ; Chong, Song ;
The Journal of Korean Institute of Communications and Information Sciences, volume 38A, issue 12, 2013, Pages 1125~1134
DOI : 10.7840/kics.2013.38A.12.1125
Small cells such as pico or femto cells are promising as a solution to cope with higher traffic explosion and the large number of users. However, the users within small cells are likely to suffer severe inter-cell interference (ICI) from neighboring base stations (BSs). To tackle this, several papers suggest BS transmit power on/off control algorithms which increase edge user throughput. However, these algorithms require centralized coordinator and have high computational complexity. This paper makes a contribution towards presenting fully distributed and low complex joint BS on/off control and user scheduling algorithm (FDA) by selecting on/off pattern of BSs. Throughput the extensive simulations, we verify the performance of our algorithm as follows: (i) Our FDA provides better throughput performance of cell edge users by 170% than the algorithm without the ICI management. (ii) Our FDA catches up with the performance of optimal algorithm by 88-96% in geometric average throughput and sufficiently small gap in edge user throughput.
DANCE : Small AP On/Off Algorithms in Ultra Dense Wireless Network
Lee, Gilsoo ; Kim, Hongseok ; Kim, Young-Tae ; Kim, Byoung-Hoon ;
The Journal of Korean Institute of Communications and Information Sciences, volume 38A, issue 12, 2013, Pages 1135~1144
DOI : 10.7840/kics.2013.38A.12.1135
Deploying small cells is a reliable and influential solution to handle the skyrocketing traffic increase in the cellular network, and the small cell technology is evolving to ultra-dense network (UDN). In this paper we propose a small cell on/off algorithm with a simple but essential framework composed of access point (AP), user equipment (UE), and small cell controller (SCC). We propose Device-Assisted Networking for Cellular grEening (DANCE) algorithms that save the energy consumption by tying to minimize the number of turned-on APs while maintaining the network throughput. In doing so, SCC firstly gathers the feedback messages from UEs and then makes a decision including a set of turned-on APs and user association. DANCE algorithm has several variations depending on the number of bits of the UE's feedback message (1 bit vs. N bit), and is divided into AP-first, UE-first, or Proximity ON according to the criteria of selecting the turned-on APs. We perform extensive simulations under the realistic UDN environment, and the results confirm that the proposed algorithms, compared to the baseline, can significantly enhance the energy efficiency, e.g., more than a factor of 10.
Low-power Butterfly Structure for DIT Radix-4 FFT Implementation
Jang, Young-Beom ; Lee, Sang-Woo ;
The Journal of Korean Institute of Communications and Information Sciences, volume 38A, issue 12, 2013, Pages 1145~1147
DOI : 10.7840/kics.2013.38A.12.1145
There are two FFT(Fast Fourier Transform) algorithms, which are DIT(Decimation-In-Time) and DIF(Decimation-In- Frequency). Even the DIF algorithm is more widely used because of its various implementation architectures, the DIT structures have not been investigated. In this paper, the DIT Radix-4 algorithm is derived and its efficient butterfly structure is proposed for SoC(System on a Chip) implementation.