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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 36, Issue 6 - Dec 2014
Volume 36, Issue 5 - Oct 2014
Volume 36, Issue 4 - Aug 2014
Volume 36, Issue 3 - Jun 2014
Volume 36, Issue 2 - Apr 2014
Volume 36, Issue 1 - Feb 2014
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Interference-Limited Dynamic Resource Management for an Integrated Satellite/Terrestrial System
Park, Unhee ; Kim, Hee Wook ; Oh, Dae Sub ; Ku, Bon-Jun ;
ETRI Journal, volume 36, issue 4, 2014, Pages 519~527
DOI : 10.4218/etrij.14.0113.0079
An integrated multi-beam satellite and multi-cell terrestrial system is an attractive means for highly efficient communication due to the fact that the two components (satellite and terrestrial) make the most of each other's resources. In this paper, a terrestrial component reuses a satellite's resources under the control of the satellite's network management system. This allows the resource allocation for the satellite and terrestrial components to be coordinated to optimize spectral efficiency and increase overall system capacity. In such a system, the satellite resources reused in the terrestrial component may bring about severe interference, which is one of the main factors affecting system capacity. Under this consideration, the objective of this paper is to achieve an optimized resource allocation in both components in such a way as to minimize any resulting inter-component interference. The objective of the proposed scheme is to mitigate this inter-component interference by optimizing the total transmission power - the result of which can lead to an increase in capacity. The simulation results in this paper illustrate that the proposed scheme affords a more energy-efficient system to be implemented, compared to a conventional power management scheme, by allocating the bandwidth uniformly regardless of the amount of interference or traffic demand.
Efficient Inter Prediction Mode Decision Method for Fast Motion Estimation in High Efficiency Video Coding
Lee, Alex ; Jun, Dongsan ; Kim, Jongho ; Choi, Jin Soo ; Kim, Jinwoong ;
ETRI Journal, volume 36, issue 4, 2014, Pages 528~536
DOI : 10.4218/etrij.14.0113.0087
High Efficiency Video Coding (HEVC) is the most recent video coding standard to achieve a higher coding performance than the previous H.264/AVC. In order to accomplish this improved coding performance, HEVC adopted several advanced coding tools; however, these cause heavy computational complexity. Similar to previous video coding standards, motion estimation (ME) of HEVC requires the most computational complexity; this is because ME is conducted for three inter prediction modes - namely, uniprediction in list 0, uniprediction in list 1, and biprediction. In this paper, we propose an efficient inter prediction mode (EIPM) decision method to reduce the complexity of ME. The proposed EIPM method computes the priority of all inter prediction modes and performs ME only on a selected inter prediction mode. Experimental results show that the proposed method reduces computational complexity arising from ME by up to 51.76% and achieves near similar coding performance compared to HEVC test model version 10.1.
Efficient ICI Self-Cancellation Scheme for OFDM Systems
Kim, Kyung-Hwa ; Seo, Bangwon ;
ETRI Journal, volume 36, issue 4, 2014, Pages 537~544
DOI : 10.4218/etrij.14.0113.0747
In this paper, we present a new inter-carrier interference (ICI) self-cancellation scheme - namely, ISC scheme - for orthogonal frequency-division multiplexing systems to reduce the ICI generated from phase noise (PHN) and residual frequency offset (RFO). The proposed scheme comprises a new ICI cancellation mapping (ICM) scheme at the transmitter and an appropriate method of combining the received signals at the receiver. In the proposed scheme, the transmitted signal is transformed into a real signal through the new ICM using the real property of the transmitted signal; the fast-varying PHN and RFO are estimated and compensated. Therefore, the ICI caused by fast-varying PHN and RFO is significantly suppressed. We also derive the carrier-to-interference power ratio (CIR) of the proposed scheme by using the symmetric conjugate property of the ICI weighting function and then compare it with those of conventional schemes. Through simulation results, we show that the proposed ISC scheme has a higher CIR and better bit error rate performance than the conventional schemes.
Sensing of OFDM Signals in Cognitive Radio Systems with Time Domain Cross-Correlation
Xu, Weiyang ;
ETRI Journal, volume 36, issue 4, 2014, Pages 545~553
DOI : 10.4218/etrij.14.0113.0758
This paper proposes an algorithm to sense orthogonal frequency-division multiplexing (OFDM) signals in cognitive radio (CR) systems. The basic idea behind this study is when a primary user is occupying a wireless channel, the covariance matrix is non-diagonal because of the time domain cross-correlation of the cyclic prefix (CP). In light of this property, a new decision metric that measures the power of the data found on two minor diagonals in the covariance matrix related to the CP is introduced. The impact of synchronization errors on the signal detection is analyzed. Besides this, a likelihood-ratio test is proposed according to the Neyman-Pearson criterion after deriving probability distribution functions of the decision metric under hypotheses of signal presence and absence. A threshold, subject to the requirement of probability of false alarm, is derived; also the probabilities of detection and false alarm are computed accordingly. Finally, numerical simulations are conducted to demonstrate the effectiveness of the proposed algorithm.
Reduction of Outage Probability due to Handover by Mitigating Inter-cell Interference in Long-Term Evolution Networks
Hussein, Yaseein Soubhi ; Ali, Borhanuddin Mohd ; Rasid, Mohd Fadlee A. ; Sali, Aduwati ;
ETRI Journal, volume 36, issue 4, 2014, Pages 554~563
DOI : 10.4218.etrij.14.0113.0947
The burgeoning growth of real-time applications, such as interactive video and VoIP, places a heavy demand for a high data rate and guarantee of QoS from a network. This is being addressed by fourth generation networks such as Long-Term Evolution (LTE). But, the mobility of user equipment that needs to be handed over to a new evolved node base-station (eNB) while maintaining connectivity with high data rates poses a significant challenge that needs to be addressed. Handover (HO) normally takes place at cell borders, which normally suffers high interference. This inter-cell interference (ICI) can affect HO procedures, as well as reduce throughput. In this paper, soft frequency reuse (SFR) and multiple preparations (MP), so-called SFRAMP, are proposed to provide a seamless and fast handover with high throughput by keeping the ICI low. Simulation results using LTE-Sim show that the outage probability and delay are reduced by 24.4% and 11.9%, respectively, over the hard handover method - quite a significant result.
Performance Analysis of Layer Pruning on Sphere Decoding in MIMO Systems
Karthikeyan, Madurakavi ; Saraswady, D. ;
ETRI Journal, volume 36, issue 4, 2014, Pages 564~571
DOI : 10.4218/etrij.14.0113.1182
Sphere decoding (SD) for multiple-input and multiple-output systems is a well-recognized approach for achieving near-maximum likelihood performance with reduced complexity. SD is a tree search process, whereby a large number of nodes can be searched in an effort to find an estimation of a transmitted symbol vector. In this paper, a simple and generalized approach called layer pruning is proposed to achieve complexity reduction in SD. Pruning a layer from a search process reduces the total number of nodes in a sphere search. The symbols corresponding to the pruned layer are obtained by adopting a QRM-MLD receiver. Simulation results show that the proposed method reduces the number of nodes to be searched for decoding the transmitted symbols by maintaining negligible performance loss. The proposed technique reduces the complexity by 35% to 42% in the low and medium signal-to-noise ratio regime. To demonstrate the potential of our method, we compare the results with another well-known method - namely, probabilistic tree pruning SD.
Multi-criteria Evaluation of Mobile Network Sharing Policies in Korea
Song, Young-Keun ; Zo, Hangjung ; Ciganek, Andrew P. ;
ETRI Journal, volume 36, issue 4, 2014, Pages 572~580
DOI : 10.4218/etrij.14.0113.1249
Mobile operators in saturated markets increasingly favor mobile network sharing (MNS) over facility-based competition. Previous research examining MNS primarily focused on its positive effects, while the negative effects were largely overlooked. This study proposes a decision-making model using an analytic hierarchy process technique to evaluate decision-making criteria among various types of MNS policies. The decision-making model was applied to Wireless Broadband services in Korea to determine the relative importance of both positive and negative evaluation criteria and preference among multiple types of MNS policies. Positive evaluation criteria (that is, efficiency) were far greater in importance than negative evaluation criteria (that is, competition harm). The preference for adopting MNS among five alternative approaches was also revealed. The study findings offer immediate policy insights in Korea and provide a decision-making framework for policy makers in other countries to utilize.
Impact of Tweets on Box Office Revenue: Focusing on When Tweets are Written
Baek, Hyunmi ; Ahn, Joongho ; Oh, Sehwan ;
ETRI Journal, volume 36, issue 4, 2014, Pages 581~590
DOI : 10.4218/etrij.14.0113.0732
This study investigates the impact of tweets on box office revenue. Specifically, the study focuses on the times when tweets were written by examining the impact of pre- and post-consumption tweets on box office revenue; an examination that is based on Expectation Confirmation Theory. The study also investigates the impact of intention tweets versus subjective tweets and the impact of negative tweets on box office revenue. Targeting 120 movies released in the US between February and August 2012, this study collected tweet information on a daily basis from two weeks before the opening until the closing and box office revenue information. The results indicate that the disconfirmation that occurs in relation to the total number of pre-consumption tweets for a movie has a negative impact on box office revenue. This premise suggests that the formation of higher expectations of a movie does not always result in positive results in situations where tweets on perceived movie quality after watching spread rapidly. This study also reveals that intention tweets have stronger effects on box office revenue than subjective tweets.
New Min-sum LDPC Decoding Algorithm Using SNR-Considered Adaptive Scaling Factors
Jung, Yongmin ; Jung, Yunho ; Lee, Seongjoo ; Kim, Jaeseok ;
ETRI Journal, volume 36, issue 4, 2014, Pages 591~598
DOI : 10.4218/etrij.14.0113.0730
This paper proposes a new min-sum algorithm for low-density parity-check decoding. In this paper, we first define the negative and positive effects of the received signal-to-noise ratio (SNR) in the min-sum decoding algorithm. To improve the performance of error correction by considering the negative and positive effects of the received SNR, the proposed algorithm applies adaptive scaling factors not only to extrinsic information but also to a received log-likelihood ratio. We also propose a combined variable and check node architecture to realize the proposed algorithm with low complexity. The simulation results show that the proposed algorithm achieves up to 0.4 dB coding gain with low complexity compared to existing min-sum-based algorithms.
Optimal Amplify-and-Forward Scheme for Parallel Relay Networks with Correlated Relay Noise
Liu, Binyue ; Yang, Ye ;
ETRI Journal, volume 36, issue 4, 2014, Pages 599~608
DOI : 10.4218/etrij.14.0113.0708
This paper studies a parallel relay network where the relays employ an amplify-and-forward (AF) relaying scheme and are subjected to individual power constraints. We consider correlated effective relay noise arising from practical scenarios when the relays are exposed to common interferers. Assuming that the noise covariance and the full channel state information are available, we investigate the problem of finding the optimal AF scheme in terms of maximum end-to-end transmission rate. It is shown that the maximization problem can be equivalently transformed to a convex semi-definite program, which can be efficiently solved. Then an upper bound on the maximum achievable AF rate of this network is provided to further evaluate the performance of the optimal AF scheme. It is proved that the upper bound can be asymptotically achieved in two special regimes when the transmit power of the source node or the relays is sufficiently large. Finally, both theoretical and numerical results are given to show that, on average, noise correlation is beneficial to the transmission rate - whether the relays know the noise covariance matrix or not.
Explicit Formulae for Characteristics of Finite-Capacity M/D/1 Queues
Seo, Dong-Won ;
ETRI Journal, volume 36, issue 4, 2014, Pages 609~616
DOI : 10.4218/etrij.14.0113.0812
Even though many computational methods (recursive formulae) for blocking probabilities in finite-capacity M/D/1 queues have already been produced, these are forms of transforms or are limited to single-node queues. Using a distinctly different approach from the usual queueing theory, this study introduces explicit (transform-free) formulae for a blocking probability, a stationary probability, and mean sojourn time under either production or communication blocking policy. Additionally, the smallest buffer capacity subject to a given blocking probability can be determined numerically from these formulae. With proper selection of the overall offered load
, the approach described herein can be applicable to more general queues from a computational point of view if the explicit expressions of random vector
Quantitative Evaluation Method for Etch Sidewall Profile of Through-Silicon Vias (TSVs)
Son, Seung-Nam ; Hong, Sang Jeen ;
ETRI Journal, volume 36, issue 4, 2014, Pages 617~624
DOI : 10.4218/etrij.14.0113.0828
Through-silicon via (TSV) technology provides much of the benefits seen in advanced packaging, such as three-dimensional integrated circuits and 3D packaging, with shorter interconnection paths for homo- and heterogeneous device integration. In TSV, a destructive cross-sectional analysis of an image from a scanning electron microscope is the most frequently used method for quality control purposes. We propose a quantitative evaluation method for TSV etch profiles whereby we consider sidewall angle, curvature profile, undercut, and scallop. A weighted sum of the four evaluated parameters, nominally total score (TS), is suggested for the numerical evaluation of an individual TSV profile. Uniformity, defined by the ratio of the standard deviation and average of the parameters that comprise TS, is suggested for the evaluation of wafer-to-wafer variation in volume manufacturing.
Design of Distributed Beamforming for Dual-Hop Multiple-Access Relay Networks
Liu, Binyue ;
ETRI Journal, volume 36, issue 4, 2014, Pages 625~634
DOI : 10.4218/etrij.14.0113.1135
This paper studies a dual-hop multiple-access relay network where two independent source nodes transmit information to a common destination node with the aid of multiple single-antenna amplify-and-forward relays. Each relay node is subject to an individual power constraint. We focus on the design of distributed beamforming schemes for the relays to support the transmission rate requirements of the two sources. To this end, we first characterize the achievable rate region for this network via solving a sequence of corner point optimization problems proposed in this paper. We also develop several low-complexity suboptimal schemes in closed form. Two inner bounds of the achievable rate region are theoretically shown to be approximately optimal in two special scenarios. Finally, numerical results demonstrate the effectiveness of our proposed approaches.
Thermal-Aware Floorplanning with Min-cut Die Partition for 3D ICs
Jang, Cheoljon ; Chong, Jong-Wha ;
ETRI Journal, volume 36, issue 4, 2014, Pages 635~642
DOI : 10.4218/etrij.14.0113.1204
Three-dimensional integrated circuits (3D ICs) implement heterogeneous systems in the same platform by stacking several planar chips vertically with through-silicon via (TSV) technology. 3D ICs have some advantages, including shorter interconnect lengths, higher integration density, and improved performance. Thermal-aware design would enhance the reliability and performance of the interconnects and devices. In this paper, we propose thermal-aware floorplanning with min-cut die partitioning for 3D ICs. The proposed min-cut die partition methodology minimizes the number of connections between partitions based on the min-cut theorem and minimizes the number of TSVs by considering a complementary set from the set of connections between two partitions when assigning the partitions to dies. Also, thermal-aware floorplanning methodology ensures a more even power distribution in the dies and reduces the peak temperature of the chip. The simulation results show that the proposed methodologies reduced the number of TSVs and the peak temperature effectively while also reducing the run-time.
Voltage Optimization of Power Delivery Networks through Power Bump and TSV Placement in 3D ICs
Jang, Cheoljon ; Chong, Jong-Wha ;
ETRI Journal, volume 36, issue 4, 2014, Pages 643~653
DOI : 10.4218/etrij.14.0113.1233
To reduce interconnect delay and power consumption while improving chip performance, a three-dimensional integrated circuit (3D IC) has been developed with die-stacking and through-silicon via (TSV) techniques. The power supply problem is one of the essential challenges in 3D IC design because IR-drop caused by insufficient supply voltage in a 3D chip reduces the chip performance. In particular, power bumps and TSVs are placed to minimize IR-drop in a 3D power delivery network. In this paper, we propose a design methodology for 3D power delivery networks to minimize the number of power bumps and TSVs with optimum mesh structure and distribute voltage variation more uniformly by shifting the locations of power bumps and TSVs while satisfying IR-drop constraint. Simulation results show that our method can reduce the voltage variation by 29.7% on average while reducing the number of power bumps and TSVs by 76.2% and 15.4%, respectively.
Broadband Finite-Difference Time-Domain Modeling of Plasmonic Organic Photovoltaics
Jung, Kyung-Young ; Yoon, Woo-Jun ; Park, Yong Bae ; Berger, Paul R. ; Teixeira, Fernando L. ;
ETRI Journal, volume 36, issue 4, 2014, Pages 654~661
DOI : 10.4218/etrij.14.0113.0767
We develop accurate finite-difference time-domain (FDTD) modeling of polymer bulk heterojunction solar cells containing Ag nanoparticles between the hole-transporting layer and the transparent conducting oxide-coated glass substrate in the wavelength range of 300 nm to 800 nm. The Drude dispersion modeling technique is used to model the frequency dispersion behavior of Ag nanoparticles, the hole-transporting layer, and indium tin oxide. The perfectly matched layer boundary condition is used for the top and bottom regions of the computational domain, and the periodic boundary condition is used for the lateral regions of the same domain. The developed FDTD modeling is employed to investigate the effect of geometrical parameters of Ag nanospheres on electromagnetic fields in devices. Although negative plasmonic effects are observed in the considered device, absorption enhancement can be achieved when favorable geometrical parameters are obtained.
Human Action Recognition Based on 3D Human Modeling and Cyclic HMMs
Ke, Shian-Ru ; Thuc, Hoang Le Uyen ; Hwang, Jenq-Neng ; Yoo, Jang-Hee ; Choi, Kyoung-Ho ;
ETRI Journal, volume 36, issue 4, 2014, Pages 662~672
DOI : 10.4218/etrij.14.0113.0647
Human action recognition is used in areas such as surveillance, entertainment, and healthcare. This paper proposes a system to recognize both single and continuous human actions from monocular video sequences, based on 3D human modeling and cyclic hidden Markov models (CHMMs). First, for each frame in a monocular video sequence, the 3D coordinates of joints belonging to a human object, through actions of multiple cycles, are extracted using 3D human modeling techniques. The 3D coordinates are then converted into a set of geometrical relational features (GRFs) for dimensionality reduction and discrimination increase. For further dimensionality reduction, k-means clustering is applied to the GRFs to generate clustered feature vectors. These vectors are used to train CHMMs separately for different types of actions, based on the Baum-Welch re-estimation algorithm. For recognition of continuous actions that are concatenated from several distinct types of actions, a designed graphical model is used to systematically concatenate different separately trained CHMMs. The experimental results show the effective performance of our proposed system in both single and continuous action recognition problems.
ID-Based Optimistic Fair Exchange Scheme Based on RSA
Youn, Taek-Young ; Chang, Ku-Young ;
ETRI Journal, volume 36, issue 4, 2014, Pages 673~681
DOI : 10.4218/etrij.14.0113.0351
Fairness of exchange is a significant property for secure online transactions, and a fair exchange scheme is a useful tool for ensuring the fairness of exchanges conducted over networks. In this paper, we propose an ID-based optimistic fair exchange scheme based on the RSA function, one which is designed by combining a well-known RSA-based signature scheme and the (naive) RSA function. Note that the main contribution of this paper is to give the first provably secure ID-based fair exchange scheme based on the RSA function, whose security can be proved under fully formalized security models. Our scheme has the following additional strongpoints. The scheme is setup-free; hence, there is no registration step between a user and an arbitrator. Moreover, the proposed scheme is designed in an ID-based setting; thus, it is possible to eliminate the need for certificates and avoid some related problems.
Efficient Near-Optimal Detection with Generalized Sphere Decoder for Blind MU-MIMO Systems
Kim, Minjoon ; Park, Jangyong ; Kim, Hyunsub ; Kim, Jaeseok ;
ETRI Journal, volume 36, issue 4, 2014, Pages 682~685
DOI : 10.4218/etrij.14.0213.0506
In this letter, we propose an efficient near-optimal detection scheme (that makes use of a generalized sphere decoder (GSD)) for blind multi-user multiple-input multiple-output (MU-MIMO) systems. In practical MU-MIMO systems, a receiver suffers from interference because the precoding matrix, the result of the precoding technique used, is quantized with limited feedback and is thus imperfect. The proposed scheme can achieve near-optimal performance with low complexity by using a GSD to detect several additional interference signals. In addition, the proposed scheme is suitable for use in blind systems.
Energy-Efficiency Power Allocation for Cognitive Radio MIMO-OFDM Systems
Zuo, Jiakuo ; Dao, Van Phuong ; Bao, Yongqiang ; Fang, Shiliang ; Zhao, Li ; Zou, Cairong ;
ETRI Journal, volume 36, issue 4, 2014, Pages 686~689
DOI : 10.4218/etrij.14.0213.0413
This paper studies energy-efficiency (EE) power allocation for cognitive radio MIMO-OFDM systems. Our aim is to minimize energy efficiency, measured by "Joule per bit" metric, while maintaining the minimal rate requirement of a secondary user under a total power constraint and mutual interference power constraints. However, since the formulated EE problem in this paper is non-convex, it is difficult to solve directly in general. To make it solvable, firstly we transform the original problem into an equivalent convex optimization problem via fractional programming. Then, the equivalent convex optimization problem is solved by a sequential quadratic programming algorithm. Finally, a new iterative energy-efficiency power allocation algorithm is presented. Numerical results show that the proposed method can obtain better EE performance than the maximizing capacity algorithm.
Quad-Band Bandpass Filter Using Quad-Mode Stub-loaded Resonators
Liu, Haiwen ; Wang, Xiaomei ; Wang, Yan ; Li, Shen ; Zhao, Yulong ; Guan, Xuehui ;
ETRI Journal, volume 36, issue 4, 2014, Pages 690~693
DOI : 10.4218/etrij.14.0213.0468
Compact multi-band bandpass filters using quad-mode stub-loaded resonators are proposed in this letter. Firstly, a novel approach about the mode-splitting characteristics of the quadruple-mode resonator is investigated, which can provide dual-band behavior. Secondly, a quad-band filter is proposed and designed by cascading two quadruple-mode resonators; the upper one operates at 1.8/2.4 GHz (GSM- and WiMax-band) and the lower one at 1.57/2.1 GHz (GPS- and WCDMA-band). Finally, the proposed filters have been fabricated. Respectable agreement between simulation and measurement verifies the validity of this design methodology.