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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Electronics and Telecommunications Research Institute
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Volume & Issues
Volume 37, Issue 6 - Dec 2015
Volume 37, Issue 5 - Oct 2015
Volume 37, Issue 4 - Aug 2015
Volume 37, Issue 3 - May 2015
Volume 37, Issue 2 - Apr 2015
Volume 37, Issue 1 - Feb 2015
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Analysis of Single-RF MIMO Receiver with Beam-Switching Antenna
Gwak, Donghyuk ; Sohn, Illsoo ; Lee, Seung Hwan ;
ETRI Journal, volume 37, issue 4, 2015, Pages 647~656
DOI : 10.4218/etrij.15.0114.0618
This paper proposes a single-RF MIMO receiver that adopts a beam-switching antenna (BSA) instead of a conventional array antenna. The beauty of the proposed single-RF MIMO receiver with BSA is that it can be deployed in a very small physical space while achieving a full spatial multiplexing gain. Our analysis has revealed that the use of a BSA inevitably results in the spectrum spreading effect at the RF output, which in turn causes an SNR decrease and adjacent channel interference (ACI). Two novel receiver techniques are proposed to mitigate the issues of redundant sub-band suppression and ACI avoidance. Numerical analysis results verify the performance improvement from the proposed receiver techniques.
Two-Stage Resource Allocation to Improve Utilization of Synchronous OFDM-PON Supporting Service Differentiation
Doo, Kyeong-Hwan ; Bang, Junseong ; Han, Man Soo ; Lee, Jonghyun ; Lee, Sangsoo ;
ETRI Journal, volume 37, issue 4, 2015, Pages 657~666
DOI : 10.4218/etrij.15.0114.0922
We propose a two-stage resource allocation algorithm for the high link utilization of an orthogonal frequency-division multiplexing passive optical network (OFDM-PON). An OFDM-PON is assumed to use a synchronous frame structure in supporting service differentiation. In distributing resources, the proposed algorithm first allocates a time window for each optical network unit (ONU), and then it arranges a subchannel, which is a group of subcarriers. This algorithm needs to satisfy two constraints. First, computations for the resource allocation should be done using a frame unit. Second, an ONU has to use a single subchannel to send upstream data for multiple services within a frame duration. We show through a computer simulation that the proposed algorithm improves the link utilization.
Design and Implementation of 256-Point Radix-4 100 Gbit/s FFT Algorithm into FPGA for High-Speed Applications
Polat, Gokhan ; Ozturk, Sitki ; Yakut, Mehmet ;
ETRI Journal, volume 37, issue 4, 2015, Pages 667~676
DOI : 10.4218/etrij.15.0114.0678
The third-party FFT IP cores available in today's markets do not provide the desired speed demands for optical communication. This study deals with the design and implementation of a 256-point Radix-4 100 Gbit/s FFT, where computational steps are reconsidered and optimized for high-speed applications, such as radar and fiber optics. Alternative methods for FFT implementation are investigated and Radix-4 is decided to be the optimal solution for our fully parallel FPGA application. The algorithms that we will implement during the development phase are to be tested on a Xilinx Virtex-6 FPGA platform. The proposed FFT core has a fully parallel architecture with a latency of nine clocks, and the target clock rate is 312.5 MHz.
Bandwidth-Efficient Precoding Scheme with Flicker Mitigation for OFDM-Based Visible Light Communications
Kim, Byung Wook ; Jung, Sung-Yoon ;
ETRI Journal, volume 37, issue 4, 2015, Pages 677~684
DOI : 10.4218/etrij.15.0114.0105
Recently, orthogonal frequency-division multiplexing (OFDM) was applied to VLC systems owing to its high rate capability. On the other hand, a real-valued unipolar OFDM signal for VLC significantly reduces bandwidth efficiency. For practical implementation, channel estimation is required for data demodulation, which causes a further decrease in spectral efficiency. In addition, the large fluctuation of an OFDM signal results in poor illumination quality, such as chromaticity changes. This paper proposes a spectrally efficient method based on a hidden-pilot-aided precoding technology for VLC with less flickering than a conventional OFDM-based method. This approach can obtain channel information without any loss of bandwidth efficiency while ensuring illumination quality by reducing the flickering effect of an OFDM-based VLC. The simulation results show that the proposed method provides a 6.4% gain in bandwidth efficiency with a 4% reduction in flicker compared to a conventional OFDM-based method.
Hybrid Multicast and Segment-Based Caching for VoD Services in LTE Networks
Choi, Kwangjin ; Choi, Seong Gon ; Choi, Jun Kyun ;
ETRI Journal, volume 37, issue 4, 2015, Pages 685~695
DOI : 10.4218/etrij.15.0114.1278
This paper proposes a novel video delivery scheme that reduces the bandwidth consumption cost from a video server to terminals in Long-Term Evolution networks. This proposed scheme combines optimized hybrid multicast with a segment-based caching strategy for use in environments where the maximum number of multicast channels is limited. The optimized hybrid multicast, allocation of multicast channels, and cache allocation are determined on the basis of a video's request rate, the related video's length, and the variable cost per unit size of a segment belonging to the related video. Performance evaluation results show that the proposed scheme reduces a video's delivery costs. This work is applicable to on-demand TV services that feature asynchronous video content requests.
Efficient Key Management Protocol for Secure RTMP Video Streaming toward Trusted Quantum Network
Pattaranantakul, Montida ; Sanguannam, Kittichai ; Sangwongngam, Paramin ; Vorakulpipat, Chalee ;
ETRI Journal, volume 37, issue 4, 2015, Pages 696~706
DOI : 10.4218/etrij.15.0114.0883
This paper presents an achievable secure videoconferencing system based on quantum key encryption in which key management can be directly applied and embedded in a server/client videoconferencing model using, for example, OpenMeeting. A secure key management methodology is proposed to ensure both a trusted quantum network and a secure videoconferencing system. The proposed methodology presents architecture on how to share secret keys between key management servers and distant parties in a secure domain without transmitting any secrets over insecure channels. The advantages of the proposed secure key management methodology overcome the limitations of quantum point-to-point key sharing by simultaneously distributing keys to multiple users; thus, it makes quantum cryptography a more practical and secure solution. The time required for the encryption and decryption may cause a few seconds delay in video transmission, but this proposed method protects against adversary attacks.
Improved TOA-Based Localization Method with BS Selection Scheme for Wireless Sensor Networks
Go, Seungryeol ; Chong, Jong-Wha ;
ETRI Journal, volume 37, issue 4, 2015, Pages 707~716
DOI : 10.4218/etrij.15.0114.1251
The purpose of a localization system is to estimate the coordinates of the geographic location of a mobile device. The accuracy of wireless localization is influenced by nonline-of-sight (NLOS) errors in wireless sensor networks. In this paper, we present an improved time of arrival (TOA)-based localization method for wireless sensor networks. TOA-based localization estimates the geographic location of a mobile device using the distances between a mobile station (MS) and three or more base stations (BSs). However, each of the NLOS errors along a distance measured from an MS (device) to a BS (device) is different because of dissimilar obstacles in the direct signal path between the two devices. To accurately estimate the geographic location of a mobile device in TOA-based localization, we propose an optimized localization method with a BS selection scheme that selects three measured distances that contain a relatively small number of NLOS errors, in this paper. Performance evaluations are presented, and the experimental results are validated through comparisons of various localization methods with the proposed method.
Energy-Aware Hybrid Cooperative Relaying with Asymmetric Traffic
Chen, Jian ; Lv, Lu ; Geng, Wenjin ; Kuo, Yonghong ;
ETRI Journal, volume 37, issue 4, 2015, Pages 717~726
DOI : 10.4218/etrij.15.0114.0522
In this paper, we study an asymmetric two-way relaying network where two source nodes intend to exchange information with the help of multiple relay nodes. A hybrid time-division broadcast relaying scheme with joint relay selection (RS) and power allocation (PA) is proposed to realize energy-efficient transmission. Our scheme is based on the asymmetric level of the two source nodes' target signal-to-noise ratio indexes to minimize the total power consumed by the relay nodes. An optimization model with joint RS and PA is studied here to guarantee hybrid relaying transmissions. Next, with the aid of our proposed intelligent optimization algorithm, which combines a genetic algorithm and a simulated annealing algorithm, the formulated optimization model can be effectively solved. Theoretical analyses and numerical results verify that our proposed hybrid relaying scheme can substantially reduce the total power consumption of relays under a traffic asymmetric scenario; meanwhile, the proposed intelligent optimization algorithm can eventually converge to a better solution.
Blind Source Separation of Instantaneous Mixture of Delayed Sources Using High-Order Taylor Approximation
Zhao, Wei ; Yuan, Zhigang ; Shen, Yuehong ; Cao, Yufan ; Wei, Yimin ; Xu, Pengcheng ; Jian, Wei ;
ETRI Journal, volume 37, issue 4, 2015, Pages 727~735
DOI : 10.4218/etrij.15.0114.0527
This paper deals with the problem of blind source separation (BSS), where observed signals are a mixture of delayed sources. In reference to a previous work, when the delay time is small such that the first-order Taylor approximation holds, delayed observations are transformed into an instantaneous mixture of original sources and their derivatives, for which an extended second-order blind identification (SOBI) approach is used to recover sources. Inspired by the results of this previous work, we propose to generalize its first-order Taylor approximation to suit higher-order approximations in the case of a large delay time based on a similar version of its extended SOBI. Compared to SOBI and its extended version for a first-order Taylor approximation, our method is more efficient in terms of separation quality when the delay time is large. Simulation results verify the performance of our approach under different time delays and signal-to-noise ratio conditions, respectively.
Improved Reliability-Based Iterative Decoding of LDPC Codes Based on Dynamic Threshold
Ma, Zhuo ; Du, Shuanyi ;
ETRI Journal, volume 37, issue 4, 2015, Pages 736~742
DOI : 10.4218/etrij.15.0113.1265
A serial concatenated decoding algorithm with dynamic threshold is proposed for low-density parity-check codes with short and medium code lengths. The proposed approach uses a dynamic threshold to select a decoding result from belief propagation decoding and order statistic decoding, which improves the performance of the decoder at a negligible cost. Simulation results show that, under a high SNR region, the proposed concatenated decoder performs better than a serial concatenated decoder without threshold with an Eb/N0 gain of above 0.1 dB.
Extracting Graphics Information for Better Video Compression
Hong, Kang Woon ; Ryu, Won ; Choi, Jun Kyun ; Lim, Choong-Gyoo ;
ETRI Journal, volume 37, issue 4, 2015, Pages 743~751
DOI : 10.4218/etrij.15.0114.0065
Cloud gaming services are heavily dependent on the efficiency of real-time video streaming technology owing to the limited bandwidths of wire or wireless networks through which consecutive frame images are delivered to gamers. Video compression algorithms typically take advantage of similarities among video frame images or in a single video frame image. This paper presents a method for computing and extracting both graphics information and an object's boundary from consecutive frame images of a game application. The method will allow video compression algorithms to determine the positions and sizes of similar image blocks, which in turn, will help achieve better video compression ratios. The proposed method can be easily implemented using function call interception, a programmable graphics pipeline, and off-screen rendering. It is implemented using the most widely used Direct3D API and applied to a well-known sample application to verify its feasibility and analyze its performance. The proposed method computes various kinds of graphics information with minimal overhead.
Implementation of Real-Time Post-Processing for High-Quality Stereo Vision
Choi, Seungmin ; Jeong, Jae-Chan ; Chang, Jiho ; Shin, Hochul ; Lim, Eul-Gyoon ; Cho, Jae Il ; Hwang, Daehwan ;
ETRI Journal, volume 37, issue 4, 2015, Pages 752~765
DOI : 10.4218/etrij.15.0114.1421
We propose a novel post-processing algorithm and its very-large-scale integration architecture that simultaneously uses the passive and active stereo vision information to improve the reliability of the three-dimensional disparity in a hybrid stereo vision system. The proposed architecture consists of four steps - left-right consistency checking, semi-2D hole filling, a tiny adaptive variance checking, and a 2D weighted median filter. The experimental results show that the error rate of the proposed algorithm (5.77%) is less than that of a raw disparity (10.12%) for a real-world camera image having a
resolution and maximum disparity of 256. Moreover, for the famous Middlebury stereo image sets, the proposed algorithm's error rate (8.30%) is also less than that of the raw disparity (13.7%). The proposed architecture is implemented on a single commercial field-programmable gate array using only 13.01% of slice resources, which achieves a rate of 60 fps for
stereo images with a disparity range of 256.
Fine-Motion Estimation Using Ego/Exo-Cameras
Uhm, Taeyoung ; Ryu, Minsoo ; Park, Jong-Il ;
ETRI Journal, volume 37, issue 4, 2015, Pages 766~771
DOI : 10.4218/etrij.15.0114.0525
Robust motion estimation for human-computer interactions played an important role in a novel method of interaction with electronic devices. Existing pose estimation using a monocular camera employs either ego-motion or exo-motion, both of which are not sufficiently accurate for estimating fine motion due to the motion ambiguity of rotation and translation. This paper presents a hybrid vision-based pose estimation method for fine-motion estimation that is specifically capable of extracting human body motion accurately. The method uses an ego-camera attached to a point of interest and exo-cameras located in the immediate surroundings of the point of interest. The exo-cameras can easily track the exact position of the point of interest by triangulation. Once the position is given, the ego-camera can accurately obtain the point of interest's orientation. In this way, any ambiguity between rotation and translation is eliminated and the exact motion of a target point (that is, ego-camera) can then be obtained. The proposed method is expected to provide a practical solution for robustly estimating fine motion in a non-contact manner, such as in interactive games that are designed for special purposes (for example, remote rehabilitation care systems).
Conservative Approximation-Based Full-Search Block Matching Algorithm Architecture for QCIF Digital Video Employing Systolic Array Architecture
Ganapathi, Hegde ; Amritha, Krishna R.S. ; Pukhraj, Vaya ;
ETRI Journal, volume 37, issue 4, 2015, Pages 772~779
DOI : 10.4218/etrij.15.0114.0504
This paper presents a power-efficient hardware realization for a motion estimation technique that is based on the full-search block matching algorithm (FSBMA). The considered input is the quarter common intermediate format of digital video. The mean of absolute difference (MAD) is the distortion criteria employed for the block matching process. The conventional architecture considered for the hardware realization of FSBMA is that of the shift register-based 2-D systolic array. For this architecture, a conservative approximation technique is adapted to eliminate unnecessary MAD computations involved in the block matching process. Upon introducing the technique to the conventional architecture, the power and complexity of its implantation is reduced, while the accuracy of the motion vector extracted from the block matching process is preserved. The proposed architecture is verified for its functional specifications. A performance evaluation of the proposed architecture is carried out using parameters such as power, area, operating frequency, and efficiency.
Audio Source Separation Based on Residual Reprojection
Cho, Choongsang ; Kim, Je Woo ; Lee, Sangkeun ;
ETRI Journal, volume 37, issue 4, 2015, Pages 780~786
DOI : 10.4218/etrij.15.0114.1311
This paper describes an audio source separation that is based on nonnegative matrix factorization (NMF) and expectation maximization (EM). For stable and highperformance separation, an effective auxiliary source separation that extracts source residuals and reprojects them onto proper sources is proposed by taking into account an ambiguous region among sources and a source's refinement. Specifically, an additional NMF (model) is designed for the ambiguous region - whose elements are not easily represented by any existing or predefined NMFs of the sources. The residual signal can be extracted by inserting the aforementioned model into the NMF-EM-based audio separation. Then, it is refined by the weighted parameters of the separation and reprojected onto the separated sources. Experimental results demonstrate that the proposed scheme (outlined above) is more stable and outperforms existing algorithms by, on average, 4.4 dB in terms of the source distortion ratio.
Fully Programmable Memory BIST for Commodity DRAMs
Kim, Ilwoong ; Jeong, Woosik ; Kang, Dongho ; Kang, Sungho ;
ETRI Journal, volume 37, issue 4, 2015, Pages 787~792
DOI : 10.4218/etrij.15.0115.0040
To accomplish a high-speed test on low-speed automatic test equipment (ATE), a new instruction-based fully programmable memory built-in self-test (BIST) is proposed. The proposed memory BIST generates a highspeed internal clock signal by multiplying an external low-speed clock signal from an ATE by a clock multiplier embedded in a DRAM. For maximum programmability and small area overhead, the proposed memory BIST stores the unique sets of instructions and corresponding test sequences that are implicit within the test algorithms that it receives from an external ATE. The proposed memory BIST is managed by an external ATE on-the-fly to perform complicated and hard-to-implement functions, such as loop operations and refresh-interrupts. Therefore, the proposed memory BIST has a simple hardware structure compared to conventional memory BIST schemes. The proposed memory BIST is a practical test solution for reducing the overall test cost for the mass production of commodity DDRx SDRAMs.
Multimodal Interface Based on Novel HMI UI/UX for In-Vehicle Infotainment System
Kim, Jinwoo ; Ryu, Jae Hong ; Han, Tae Man ;
ETRI Journal, volume 37, issue 4, 2015, Pages 793~803
DOI : 10.4218/etrij.15.0114.0076
We propose a novel HMI UI/UX for an in-vehicle infotainment system. Our proposed HMI UI comprises multimodal interfaces that allow a driver to safely and intuitively manipulate an infotainment system while driving. Our analysis of a touchscreen interface-based HMI UI/UX reveals that a driver's use of such an interface while driving can cause the driver to be seriously distracted. Our proposed HMI UI/UX is a novel manipulation mechanism for a vehicle infotainment service. It consists of several interfaces that incorporate a variety of modalities, such as speech recognition, a manipulating device, and hand gesture recognition. In addition, we provide an HMI UI framework designed to be manipulated using a simple method based on four directions and one selection motion. Extensive quantitative and qualitative in-vehicle experiments demonstrate that the proposed HMI UI/UX is an efficient mechanism through which to manipulate an infotainment system while driving.
MAC Protocols for Energy Harvesting Wireless Sensor Networks: Survey
Kosunalp, Selahattin ;
ETRI Journal, volume 37, issue 4, 2015, Pages 804~812
DOI : 10.4218/etrij.15.0115.0017
Energy harvesting (EH) technology in the field of wireless sensor networks (WSNs) is gaining increasing popularity through removing the burden of having to replace/recharge depleted energy sources by energy harvester devices. EH provides an alternative source of energy from the surrounding environment; therefore, by exploiting the EH process, WSNs can achieve a perpetual lifetime. In view of this, emphasis is being placed on the design of new medium access control (MAC) protocols that aim to maximize the lifetime of WSNs by using the maximum possible amount of harvested energy instead of saving any residual energy, given that the rate of energy harvested is greater than that which is consumed. Various MAC protocols with the objective of exploiting ambient energy have been proposed for energy-harvesting WSNs (EH-WSNs). In this paper, first, the fundamental properties of EH-WSN architecture are outlined. Then, several MAC protocols proposed for EH-WSNs are presented, describing their operating principles and underlying features. To give an insight into future research directions, open research issues (key ideas) with respect to design trade-offs are discussed at the end of this paper.
Classifying Biomedical Literature Providing Protein Function Evidence
Lim, Joon-Ho ; Lee, Kyu-Chul ;
ETRI Journal, volume 37, issue 4, 2015, Pages 813~823
DOI : 10.4218/etrij.15.0114.0041
Because protein is a primary element responsible for biological or biochemical roles in living bodies, protein function is the core and basis information for biomedical studies. However, recent advances in bio technologies have created an explosive increase in the amount of published literature; therefore, biomedical researchers have a hard time finding needed protein function information. In this paper, a classification system for biomedical literature providing protein function evidence is proposed. Note that, despite our best efforts, we have been unable to find previous studies on the proposed issue. To classify papers based on protein function evidence, we should consider whether the main claim of a paper is to assert a protein function. We, therefore, propose two novel features - protein and assertion. Our experimental results show a classification performance with 71.89% precision, 90.0% recall, and a 79.94% F-measure. In addition, to verify the usefulness of the proposed classification system, two case study applications are investigated - information retrieval for protein function and automatic summarization for protein function text. It is shown that the proposed classification system can be successfully applied to these applications.
Heart Sound Localization in Respiratory Sounds Based on Singular Spectrum Analysis and Frequency Features
Molaie, Malihe ; Moradi, Mohammad Hassan ;
ETRI Journal, volume 37, issue 4, 2015, Pages 824~832
DOI : 10.4218/etrij.15.0114.1447
Heart sounds are the main obstacle in lung sound analysis. To tackle this obstacle, we propose a diagnosis algorithm that uses singular spectrum analysis (SSA) and frequency features of heart and lung sounds. In particular, we introduce a frequency coefficient that shows the frequency difference between heart and lung sounds. The proposed algorithm is applied to a synthetic mixture of heart and lung sounds. The results show that heart sounds can be extracted successfully and localizations for the first and second heart sounds are remarkably performed. An error analysis of the localization results shows that the proposed algorithm has fewer errors compared to the SSA method, which is one of the most powerful methods in the localization of heart sounds. The presented algorithm is also applied in the cases of recorded respiratory sounds from the chest walls of five healthy subjects. The efficiency of the algorithm in extracting heart sounds from the recorded breathing sounds is verified with power spectral density evaluations and listening. Most studies have used only normal respiratory sounds, whereas we additionally use abnormal breathing sounds to validate the strength of our achievements.