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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 32, Issue 6 - Dec 2010
Volume 32, Issue 5 - Oct 2010
Volume 32, Issue 4 - Aug 2010
Volume 32, Issue 3 - Jun 2010
Volume 32, Issue 2 - Apr 2010
Volume 32, Issue 1 - Feb 2010
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A Low-Complexity 128-Point Mixed-Radix FFT Processor for MB-OFDM UWB Systems
Cho, Sang-In ; Kang, Kyu-Min ;
ETRI Journal, volume 32, issue 1, 2010, Pages 1~10
DOI : 10.4218/etrij.10.0109.0232
In this paper, we present a fast Fourier transform (FFT) processor with four parallel data paths for multiband orthogonal frequency-division multiplexing ultra-wideband systems. The proposed 128-point FFT processor employs both a modified radix-
algorithm and a radix-
algorithm to significantly reduce the numbers of complex constant multipliers and complex booth multipliers. It also employs substructure-sharing multiplication units instead of constant multipliers to efficiently conduct multiplication operations with only addition and shift operations. The proposed FFT processor is implemented and tested using 0.18
CMOS technology with a supply voltage of 1.8 V. The hardware- efficient 128-point FFT processor with four data streams can support a data processing rate of up to 1 Gsample/s while consuming 112 mW. The implementation results show that the proposed 128-point mixed-radix FFT architecture significantly reduces the hardware cost and power consumption in comparison to existing 128-point FFT architectures.
Novel UWB Transceiver for WBAN Networks: A Study on AWGN Channels
Zhao, Chengshi ; Zhou, Zheng ; Kwak, Kyung-Sup ;
ETRI Journal, volume 32, issue 1, 2010, Pages 11~21
DOI : 10.4218/etrij.10.0108.0738
A novel ultra-wideband (UWB) transceiver structure is presented to be used in wireless body area networks (WBANs). In the proposed structure, a data channel and a control channel are combined into a single transmission signal. In the signal, a modulation method mixing pulse position modulation and pulse amplitude modulation is proposed. A mathematical framework calculating the power spectrum density of the proposed pulse-based signal evaluates its coexistence with conventional radio systems. The transceiver structure is discussed, and the receiving performance is investigated in the additive white Gaussian noise channel. It is demonstrated that the proposed scheme is easier to match to the UWB emission mask than conventional UWB systems. The proposed scheme achieves the data rate requirement of WBAN; the logical control channel achieves better receiving performance than the logical data channel, which is useful for controlling and maintaining networks. The proposed scheme is also easy to implement.
Game Traffic Classification Using Statistical Characteristics at the Transport Layer
Han, Young-Tae ; Park, Hong-Shik ;
ETRI Journal, volume 32, issue 1, 2010, Pages 22~32
DOI : 10.4218/etrij.10.0109.0236
The pervasive game environments have activated explosive growth of the Internet over recent decades. Thus, understanding Internet traffic characteristics and precise classification have become important issues in network management, resource provisioning, and game application development. Naturally, much attention has been given to analyzing and modeling game traffic. Little research, however, has been undertaken on the classification of game traffic. In this paper, we perform an interpretive traffic analysis of popular game applications at the transport layer and propose a new classification method based on a simple decision tree, called an alternative decision tree (ADT), which utilizes the statistical traffic characteristics of game applications. Experimental results show that ADT precisely classifies game traffic from other application traffic types with limited traffic features and a small number of packets, while maintaining low complexity by utilizing a simple decision tree.
Harmonic Identification Algorithms Based on DCT for Power Quality Applications
Yepes, Alejandro G. ; Freijedo, Francisco D. ; Doval-Gandoy, Jesus ; Sanchez, Oscar Lopez ; Fernandez-Comesana, Pablo ; Alvarez, Jano Malvar ;
ETRI Journal, volume 32, issue 1, 2010, Pages 33~43
DOI : 10.4218/etrij.10.0109.0342
The increasing demand for non-sinusoidal currents affects the quality of distribution networks. Harmonic detection is a crucial step in the cancellation of those components by active power filters. In this paper, the discrete cosine transform (DCT) is compared with different implementations based on Fourier transforms, demonstrating their equivalences and the advantages provided by the former. We demonstrate that the phase error in the presence of grid frequency deviations and the transient length are reduced by half in comparison to the discrete Fourier transform. A novel algorithm is developed to provide frequency adaptation to the DCT, taking advantage of its good features. The window width is adjusted in real time according to the actual value of the grid fundamental frequency by means of a phase-locked loop. A technique based on dithering is employed to overcome the limitation caused by the truncation of the window number of samples, so the frequency resolution is enhanced. The theoretical approach is verified by simulated and experimental results.
Improvement of Ultra-wideband Link Performance over Bands Requiring Interference Mitigation in Korea
Rateb, Ahmad M. ; Syed-Yusof, Syarifah Kamilah ; Fisal, Norsheila ;
ETRI Journal, volume 32, issue 1, 2010, Pages 44~52
DOI : 10.4218/etrij.10.0109.0218
Ultra-wideband (UWB) systems have witnessed a debate over whether they may cause interference to other existing and future narrowband systems sharing their band of operation. The detect and avoid (DAA) mechanism was developed as a solution to reduce interference to narrowband systems in order to ease regulatory concerns. It works by adaptively reducing the transmitted power at the overlapping bands upon detecting an active narrowband link. However, employing DAA degrades the performance of UWB transmissions. In this paper, we present the Korean UWB regulations as an example of regulations that require DAA in certain bands. We investigate DAA's impact on performance and propose a method to mitigate it, which provides UWB with the more efficient support of the DAA mechanism and enables it to avoid a larger number of narrowband users while sustaining the data rate. Results show significant improvement in performance with the application of our technique compared to conventional performance.
Electronic Feedback System for Stabilization of Fiber Ring Resonator
Sang-Ngern, Sommart ; Roeksabutr, Athikom ;
ETRI Journal, volume 32, issue 1, 2010, Pages 53~61
DOI : 10.4218/etrij.10.0109.0320
We propose a simple technique to stabilize the optical output intensity of a fiber ring resonator. The electronic feedback circuit system, which consists of two voltage control oscillators, a phase comparator, and a low pass filter, is applied to the fiber ring resonator in order to compensate the optical phase shift in the ring loop. The reference electrical signal determines the operating condition of the fiber ring resonator for the desired optical output signal. The experimental results within the operating range agree well with the analytical results. The simulated performance of the proposed model is also compared with that of other existing models and shows significant improvement over them.
Design of an Internal Antenna with Near-Omnidirectional H-Plane Radiation Pattern over Ultra-wide Bandwidth
Lee, Young-Ki ; Hong, Seok-Jin ; Kim, Jeong-Pyo ; Choi, Jae-Hoon ;
ETRI Journal, volume 32, issue 1, 2010, Pages 62~67
DOI : 10.4218/etrij.10.0109.0271
In this paper, an ultra-wideband internal antenna for use in mobile applications is proposed. The proposed antenna has symmetrical bi-arm structures printed on the top and bottom of the substrate, and it occupies a compact area of 10 mm
1 mm. The designed antenna has an impedance bandwidth from 3 GHz to 12 GHz and near omnidirectional radiation patterns over the frequency band of interest. The group delay between two antennas fabricated using the proposed design is less than 0.8 ns, and the maximum gain variation is about 3.16 dB.
Effects of Channel Electron In-Plane Velocity on the Capacitance-Voltage Curve of MOS Devices
Mao, Ling-Feng ;
ETRI Journal, volume 32, issue 1, 2010, Pages 68~72
DOI : 10.4218/etrij.10.0109.0386
The coupling between the transverse and longitudinal components of the channel electron motion in NMOS devices leads to a reduction in the barrier height. Therefore, this study theoretically investigates the effects of the in-plane velocity of channel electrons on the capacitance-voltage characteristics of nano NMOS devices under inversion bias. Numerical calculation via a self-consistent solution to the coupled Schrodinger equation and Poisson equation is used in the investigation. The results demonstrate that such a coupling largely affects capacitance-voltage characteristic when the in-plane velocity of channel electrons is high. The ballistic transport ensures a high in-plane momentum. It suggests that such a coupling should be considered in the quantum capacitance-voltage modeling in ballistic transport devices.
MC-MIPOG: A Parallel t-Way Test Generation Strategy for Multicore Systems
Younis, Mohammed I. ; Zamli, Kamal Z. ;
ETRI Journal, volume 32, issue 1, 2010, Pages 73~83
DOI : 10.4218/etrij.10.0109.0266
Combinatorial testing has been an active research area in recent years. One challenge in this area is dealing with the combinatorial explosion problem, which typically requires a very expensive computational process to find a good test set that covers all the combinations for a given interaction strength (t). Parallelization can be an effective approach to manage this computational cost, that is, by taking advantage of the recent advancement of multicore architectures. In line with such alluring prospects, this paper presents a new deterministic strategy, called multicore modified input parameter order (MC-MIPOG) based on an earlier strategy, input parameter order generalized (IPOG). Unlike its predecessor strategy, MC-MIPOG adopts a novel approach by removing control and data dependency to permit the harnessing of multicore systems. Experiments are undertaken to demonstrate speedup gain and to compare the proposed strategy with other strategies, including IPOG. The overall results demonstrate that MC-MIPOG outperforms most existing strategies (IPOG, IPOF, IPOF2, IPOG-D, ITCH, TConfig, Jenny, and TVG) in terms of test size within acceptable execution time. Unlike most strategies, MC-MIPOG is also capable of supporting high interaction strengths of t > 6.
Dual-Port SDRAM Optimization with Semaphore Authority Management Controller
Kim, Jae-Hwan ; Chong, Jong-Wha ;
ETRI Journal, volume 32, issue 1, 2010, Pages 84~92
DOI : 10.4218/etrij.10.0109.0262
This paper proposes the semaphore authority management (SAM) controller to optimize the dual-port SDRAM (DPSDRAM) in the mobile multimedia systems. Recently, the DPSDRAM with a shared bank enabling the exchange of data between two processors at high speed has been developed for mobile multimedia systems based on dual-processors. However, the latency of DPSDRAM caused by the semaphore for preventing the access contention at the shared bank slows down the data transfer rate and reduces the memory bandwidth. The methodology of SAM increases the data transfer rate by minimizing the semaphore latency. The SAM prevents the latency of reading the semaphore register of DPSDRAM, and reduces the latency of waiting for the authority of the shared bank to be changed. It also reduces the number of authority requests and the number of times authority changes. The experimental results using a 1 Gb DPSDRAM (OneDRAM) with the SAM controllers at 66 MHz show 1.6 times improvement of the data transfer rate between two processors compared with the traditional controller. In addition, the SAM shows bandwidth enhancement of up to 38% for port A and 31% for port B compared with the traditional controller.
Linear Corrector Overcoming Minimum Distance Limitation for Secure TRNG from (17, 9, 5) Quadratic Residue Code
Kim, Young-Sik ; Jang, Ji-Woong ; Lim, Dae-Woon ;
ETRI Journal, volume 32, issue 1, 2010, Pages 93~101
DOI : 10.4218/etrij.10.0109.0141
A true random number generator (TRNG) is widely used to generate secure random numbers for encryption, digital signatures, authentication, and so on in crypto-systems. Since TRNG is vulnerable to environmental changes, a deterministic function is normally used to reduce bias and improve the statistical properties of the TRNG output. In this paper, we propose a linear corrector for secure TRNG. The performance of a linear corrector is bounded by the minimum distance of the corresponding linear error correcting code. However, we show that it is possible to construct a linear corrector overcoming the minimum distance limitation. The proposed linear corrector shows better performance in terms of removing bias in that it can enlarge the acceptable bias range of the raw TRNG output. Moreover, it is possible to efficiently implement this linear corrector using only XOR gates, which must have a suitable hardware size for embedded security systems.
Practical Second-Order Correlation Power Analysis on the Message Blinding Method and Its Novel Countermeasure for RSA
Kim, Hee-Seok ; Kim, Tae-Hyun ; Yoon, Joong-Chul ; Hong, Seok-Hie ;
ETRI Journal, volume 32, issue 1, 2010, Pages 102~111
DOI : 10.4218/etrij.10.0109.0249
Recently power attacks on RSA cryptosystems have been widely investigated, and various countermeasures have been proposed. One of the most efficient and secure countermeasures is the message blinding method, which includes the RSA derivative of the binary-with-random-initial-point algorithm on elliptical curve cryptosystems. It is known to be secure against first-order differential power analysis (DPA); however, it is susceptible to second-order DPA. Although second-order DPA gives some solutions for defeating message blinding methods, this kind of attack still has the practical difficulty of how to find the points of interest, that is, the exact moments when intermediate values are being manipulated. In this paper, we propose a practical second-order correlation power analysis (SOCPA). Our attack can easily find points of interest in a power trace and find the private key with a small number of power traces. We also propose an efficient countermeasure which is secure against the proposed SOCPA as well as existing power attacks.
Sheetlike Waveguide for 2.4 GHz and 5 GHz Bands
Eom, Kun-Sun ; Hiroyuki, Arai ;
ETRI Journal, volume 32, issue 1, 2010, Pages 112~119
DOI : 10.4218/etrij.10.0109.0142
We present a useful design for a free access mat which supports two frequency bands of 2.4 GHz and 5 GHz. The free access mat is a sheet-shaped waveguide which consists of a tightly coupled double-layered microstrip resonator array. It provides easy access for devices in short-range wireless communications. Interference is a common problem with conventional applications which use free space transmission. Our proposed wireless access system uses a subsidiary waveguide, the free access mat. Wireless devices are proximately coupled to the free access mat through which the coupled electromagnetic (EM) wave transmits. The arrival domain of the EM wave of an application is therefore limited to an area close to the free access mat. Wireless devices can be coupled to the free access mat at an arbitrary position without contact. We previously presented a free access mat for a single frequency band. This paper presents a free access mat for the two frequency bands of 2.4 GHz and 5 GHz. The free access mat uses a ring patch resonator array which is easily excited by typical antennas and is resistant to interference. These characteristics are demonstrated by numerical simulation and confirmed by experiment.
Modified Fixed-Threshold SMO for 1-Slack Structural SVMs
Lee, Chang-Ki ; Jang, Myung-Gil ;
ETRI Journal, volume 32, issue 1, 2010, Pages 120~128
DOI : 10.4218/etrij.10.0109.0425
In this paper, we describe a modified fixed-threshold sequential minimal optimization (FSMO) for 1-slack structural support vector machine (SVM) problems. Because the modified FSMO uses the fact that the formulation of 1-slack structural SVMs has no bias, it breaks down the quadratic programming (QP) problems of 1-slack structural SVMs into a series of smallest QP problems, each involving only one variable. For various test sets, the modified FSMO is as accurate as existing structural SVM implementations (n-slack and 1-slack SVM-struct) but is faster on large data sets.
Mobile Telecommunications Market Regulations and Carrier Performance: The Korean Case
Park, Chu-Hwan ; Han, Sung-Soo ; Seok, Wang-Hun ;
ETRI Journal, volume 32, issue 1, 2010, Pages 129~138
DOI : 10.4218/etrij.10.0109.0179
This paper qualitatively and quantitatively examines the effectiveness of regulations currently in place in the Korean mobile telecommunications market by comparing their intended objectives with the actual outcome, particularly with respect to the performance of market participants. The results show that the regulations have generally been effective in lowering the average revenue per user of carriers. However, the managed competition efforts of the government have also resulted in increased revenues for the top two carriers in the market without significantly affecting their general business operations.
Performance of Selective Decode-and-Forward Relay Networks with Partial Channel Information
Rui, Xianyi ;
ETRI Journal, volume 32, issue 1, 2010, Pages 139~141
DOI : 10.4218/etrij.10.0209.0329
In this letter, closed-form approximations for outage probability and symbol error rate are presented for a selective decode-and-forward relay network with partial channel information. An independent but not identically distributed Rayleigh fading environment is considered. Numerical and simulated results demonstrate the validity of the analytical results.
GPS L5 Acquisition Schemes for Fast Code Detection and Improved Doppler Accuracy
Joo, In-One ; Sin, Cheon-Sig ; Lee, Sang-Uk ; Kim, Jae-Hoon ;
ETRI Journal, volume 32, issue 1, 2010, Pages 142~144
DOI : 10.4218/etrij.10.0209.0414
In this letter, we propose GPS L5 acquisition schemes to detect a fast code phase and improve the accuracy of the Doppler frequency. The proposed approach is based on the code-phase changes which occur during the acquisition processing time originating in the Doppler frequency. The proposed schemes detect a fast code phase within about 1 chip near the estimated code phase and improve the accuracy of the Doppler frequency by up to about 4 times in comparison with the popular Septentrio receiver. The feasibility of the proposed schemes is demonstrated through simulation.
Approximation for the Two-Dimensional Gaussian Q-Function and Its Applications
Park, Jin-Ah ; Park, Seung-Keun ;
ETRI Journal, volume 32, issue 1, 2010, Pages 145~147
DOI : 10.4218/etrij.10.0209.0352
In this letter, we present a new approximation for the twodimensional (2-D) Gaussian Q-function. The result is represented by only the one-dimensional (1-D) Gaussian Q-function. Unlike the previous 1-D Gaussian-type approximation, the presented approximation can be applied to compute the 2-D Gaussian Q-function with large correlations.
Compact Planar Dual-Wideband Bandstop Filters with Cross Coupling and Open-Ended Stepped Impedance Resonators
Velidi, Vamsi Krishna ; Sanyal, Subrata ;
ETRI Journal, volume 32, issue 1, 2010, Pages 148~150
DOI : 10.4218/etrij.10.0209.0341
This letter presents the design of a compact bandstop filter (BSF) operating at two frequencies. The proposed BSF consists of open-ended stepped impedance resonators (OSIR) and an end-shorted parallel-coupled microstrip line (E-PCML). The OSIRs are used to achieve the impedance-controlled stopband positions. The wide BSF bandwidths are achieved through enhanced coupling of the E-PCML. Explicit design guidelines are derived using a lossless transmission line model. To validate theoretical predictions, a prototype dual-band BSF operating at 900 MHz and 2,100 MHz with fractional bandwidths of 72% and 36%, respectively, is implemented in microstrip.
Fully Integrated HBT MMIC Series-Type Extended Doherty Amplifier for W-CDMA Handset Applications
Koo, Chan-Hoe ; Kim, Jung-Hyun ; Kwon, Young-Woo ;
ETRI Journal, volume 32, issue 1, 2010, Pages 151~153
DOI : 10.4218/etrij.10.0209.0360
A highly efficient linear and compactly integrated series-type Doherty power amplifier (PA) has been developed for wideband code-division multiple access handset applications. To overcome the size limit of a typical Doherty amplifier, all circuit elements, such as matching circuits and impedance transformers, are fully integrated into a single monolithic microwave integrated circuit (MMIC). The implemented PA shows a very low idle current of 25 mA and an excellent power-added efficiency of 25.1% at an output power of 19 dBm by using an extended Doherty concept. Accordingly, its average current consumption was reduced by 51% and 41% in urban and suburban environments, respectively, when compared with a class-AB PA. By adding a simple predistorter to the PA, the PA showed an adjacent channel leakage ratio better than -42 dBc over the whole output power range.
Measurement Accuracy of Oscillation-Based Test of Analog-to-Digital Converters
Mrak, Peter ; Biasizzo, Anton ; Novak, Franc ;
ETRI Journal, volume 32, issue 1, 2010, Pages 154~156
DOI : 10.4218/etrij.10.0209.0285
Oscillation-based testing of analog-to-digital converters represents a viable option for low-cost built-in self-testing in mixed-signal design. While numerous papers have addressed implementation issues, little attention has been paid to the measurement accuracy. In this letter, we highlight an inherent measurement uncertainty which has to be considered when deriving the parameters from the oscillation frequency.
TRE+: Extended Tree-Based Routing Ethernet
Carral, Juan A. ; Ibanez, Guillermo ; Garcia-Martinez, Alberto ; Lopez-Carmona, Miguel A. ; Marsa-Maestre, Ivan ;
ETRI Journal, volume 32, issue 1, 2010, Pages 157~159
DOI : 10.4218/etrij.10.0209.0388
Tree-based routing Ethernet (TRE) is a recent Ethernet architecture that enables shortcut links to improve performance compared to spanning tree protocols. However, TRE can only use shortcuts that arrive directly at bridges located in the branch of the destination. TRE+ extends the topology knowledge of a bridge to 2 hops away, thus unveiling new shortcuts to the destination branch. Simulations show a major performance improvement of TRE+ compared to TRE, with results close to shortest paths in some topologies.
Maximum Likelihood Training and Adaptation of Embedded Speech Recognizers for Mobile Environments
Cho, Young-Kyu ; Yook, Dong-Suk ;
ETRI Journal, volume 32, issue 1, 2010, Pages 160~162
DOI : 10.4218/etrij.10.0209.0242
For the acoustic models of embedded speech recognition systems, hidden Markov models (HMMs) are usually quantized and the original full space distributions are represented by combinations of a few quantized distribution prototypes. We propose a maximum likelihood objective function to train the quantized distribution prototypes. The experimental results show that the new training algorithm and the link structure adaptation scheme for the quantized HMMs reduce the word recognition error rate by 20.0%.
Fast 3D Mesh Compression Using Shared Vertex Analysis
Jang, Euee-Seon ; Lee, Seung-Wook ; Koo, Bon-Ki ; Kim, Dai-Yong ; Son, Kyoung-Soo ;
ETRI Journal, volume 32, issue 1, 2010, Pages 163~165
DOI : 10.4218/etrij.10.0209.0357
A trend in 3D mesh compression is codec design with low computational complexity which preserves the input vertex and face order. However, this added information increases the complexity. We present a fast 3D mesh compression method that compresses the redundant shared vertex information between neighboring faces using simple first-order differential coding followed by fast entropy coding with a fixed length prefix. Our algorithm is feasible for low complexity designs and maintains the order, which is now part of the MPEG-4 scalable complexity 3D mesh compression standard. The proposed algorithm is 30 times faster than MPEG-4 3D mesh coding extension.
Symmetric Adiabatic Logic Circuits against Differential Power Analysis
Choi, Byong-Deok ; Kim, Kyung-Eun ; Chung, Ki-Seok ; Kim, Dong-Kyue ;
ETRI Journal, volume 32, issue 1, 2010, Pages 166~168
DOI : 10.4218/etrij.10.0209.0247
We investigate the possibility of using adiabatic logic as a countermeasure against differential power analysis (DPA) style attacks to make use of its energy efficiency. Like other dual-rail logics, adiabatic logic exhibits a current dependence on input data, which makes the system vulnerable to DPA. To resolve this issue, we propose a symmetric adiabatic logic in which the discharge paths are symmetric for data-independent parasitic capacitance, and the charges are shared between the output nodes and between the internal nodes, respectively, to prevent the circuit from depending on the previous input data.
Value of Number Portability on Internet Phones
Ku, Jung-Eun ; Lee, Sang-Woo ; Hyun, Tchang-Hee ;
ETRI Journal, volume 32, issue 1, 2010, Pages 169~171
DOI : 10.4218/etrij.10.0209.0356
Even though Internet phone service (IPS) continues to evolve in terms of quality and competitive pricing compared with the public switched telephone network (PSTN), the number of Internet phone subscribers is still low in South Korea. The Korean government decided to apply number portability to the IPS market in 2008. This study expresses its value in monetary terms with a contingent valuation approach. With this methodology, this study investigates the willingness of 316 current PSTN subscribers to pay for IPS, using a specific survey method called double-bounded dichotomous choices, to obtain more accurate data. The results show that the calculated value of Internet phone number portability positively impacts consumer welfare.