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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal DOI :
Electronics and Telecommunications Research Institute
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Volume & Issues
Volume 29, Issue 6 - Dec 2007
Volume 29, Issue 5 - Oct 2007
Volume 29, Issue 4 - Aug 2007
Volume 29, Issue 3 - Jun 2007
Volume 29, Issue 2 - Apr 2007
Volume 29, Issue 1 - Feb 2007
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RETRACTED: Double-Dwell Hybrid Acquisition in a DS-UWB System
Wang, Yupeng ; Chang, Kyung-Hi ;
ETRI Journal, volume 29, issue 1, 2007, Pages 1~7
In this paper, we analyze the performance of double-dwell hybrid initial acquisition in a direct sequence ultra-wideband (DS-UWB) system via detection, miss, false alarm probabilities, and mean acquisition time. In the analysis, we consider the effect of the acquisition sequence as well as the deployment scenario of the abundant multipath components over small coverage of the piconet in the DS-UWB system. Based on the simulation, we obtain various performance measures for the mean acquisition time by varying parameters such as the total number of hypotheses to be searched, subgroup size, and dwell time. We thereupon suggest the optimum parameter set for the initial acquisition in the DS-UWB system.
TD-CFIE Formulation for Transient Electromagnetic Scattering from 3-D Dielectric Objects
Lee, Young-Hwan ; Jung, Baek-Ho ; Sarkar, Tapan K. ; Yuan, Mengtao ; Ji, Zhong ; Park, Seong-Ook ;
ETRI Journal, volume 29, issue 1, 2007, Pages 8~17
In this paper, we present a time domain combined field integral equation formulation (TD-CFIE) to analyze the transient electromagnetic response from dielectric objects. The solution method is based on the method of moments which involves separate spatial and temporal testing procedures. A set of the RWG functions is used for spatial expansion of the equivalent electric and magnetic current densities, and a combination of RWG and its orthogonal component is used for spatial testing. The time domain unknowns are approximated by a set of orthonormal basis functions derived from the Laguerre polynomials. These basis functions are also used for temporal testing. Use of this temporal expansion function characterizing the time variable makes it possible to handle the time derivative terms in the integral equation and decouples the space-time continuum in an analytic fashion. Numerical results computed by the proposed formulation are compared with the solutions of the frequency domain combined field integral equation.
Improved Redundant Picture Coding Using Polyphase Downsampling for H.264
Jia, Jie ; Choi, Hae-Chul ; Kim, Jae-Gon ; Kim, Hae-Kwang ; Chang, Yilin ;
ETRI Journal, volume 29, issue 1, 2007, Pages 18~26
This paper presents an improved redundant picture coding method that efficiently enhances the error resiliency of H.264. The proposed method applies polyphase downsampling to residual blocks obtained from inter prediction and selectively encodes the rearranged residual blocks in the redundant picture coding process. Moreover, a spatial-temporal sample construction method is developed for the redundant coded picture, which further improves the reconstructed picture quality in error prone environments. Simulations based on JM11.0 were run to verify the proposed method on different test sequences in various error prone environments with average packet loss rates of 3%, 5%, 10%, and 20%. Results of the simulations show that the presented method significantly improves the robustness of H.264 to packet loss by 1.6 dB PSNR on average over the conventional redundant picture coding method.
Energy Savings in OFDM Systems through Cooperative Relaying
Khuong, Ho Van ; Kong, Hyung-Yun ;
ETRI Journal, volume 29, issue 1, 2007, Pages 27~35
Energy savings in orthogonal frequency division multiplexing (OFDM) systems is an active research area. In order to achieve a solution, we propose a new cooperative relaying scheme operated on a per subcarrier basis. This scheme improves the bit error rate (BER) performance of the conventional signal-to-noise ratio (SNR)-based selection relaying scheme by substituting SNR with symbol error probability (SEP) to evaluate the received signal quality at the relay more reliably. Since the cooperative relaying provides spatial diversity gain for each subcarrier, thus statistically enhancing the reliability of subcarriers at the destination, the total number of lost subcarriers due to deep fading is reduced. In other words, cooperative relaying can alleviate error symbols in a codeword so that the error correction capability of forward error correction codes can be fully exploited to improve the BER performance (or save transmission energy at a target BER). Monte-Carlo simulations validate the proposed approach.
Analysis of Frequency Selective Surface on Isotropic/Anisotropic Layers Using WCIP Method
Titaouine, Mohammed ; Gomes, Alfredo Neto ; Baudrand, Henry ; Djahli, Farid ;
ETRI Journal, volume 29, issue 1, 2007, Pages 36~44
The wave concept iterative procedure (WCIP) is used to analyze arbitrarily shaped frequency selective surfaces (FSS). The WCIP method is developed from the fast modal transform based on a two-dimensional fast Fourier transform algorithm. Using the proposed procedure, less computing time and memory are needed to calculate the scattering parameters of the FSS structure. The method is applied to the modeling of an FSS structure of a rectangular patch and a comparison with experimental results confirms good agreement.
An Offset-Compensated LVDS Receiver with Low-Temperature Poly-Si Thin Film Transistor
Min, Kyung-Youl ; Yoo, Chang-Sik ;
ETRI Journal, volume 29, issue 1, 2007, Pages 45~49
The poly-Si thin film transistor (TFT) shows large variations in its characteristics due to the grain boundary of poly-crystalline silicon. This results in unacceptably large input offset of low-voltage differential signaling (LVDS) receivers. To cancel the large input offset of poly-Si TFT LVDS receivers, a full-digital offset compensation scheme has been developed and verified to be able to keep the input offset under 15 mV which is sufficiently small for LVDS signal receiving.
On Diagonal Loading for Robust Adaptive Beamforming Based on Worst-Case Performance Optimization
Lin, Jing-Ran ; Peng, Qi-Cong ; Shao, Huai-Zong ;
ETRI Journal, volume 29, issue 1, 2007, Pages 50~58
Robust adaptive beamforming based on worst-case performance optimization is investigated in this paper. It improves robustness against steering vector mismatches by the approach of diagonal loading. A closed-form solution to optimal loading is derived after some approximations. Besides reducing the computational complexity, it shows how different factors affect the optimal loading. Based on this solution, a performance analysis of the beamformer is carried out. As a consequence, approximated closed-form expressions of the source-of-interest power estimation and the output signalto-interference-plus-noise ratio are presented in order to predict its performance. Numerical examples show that the proposed closed-form expressions are very close to their actual values.
Light-Adaptive CMOS Vision Chip for Edge Detection Based on a Retinal Structure Using a Saturating Resistive Network
Kong, Jae-Sung ; Kim, Sang-Heon ; Sung, Dong-Kyu ; Shin, Jang-Kyoo ;
ETRI Journal, volume 29, issue 1, 2007, Pages 59~69
We designed and fabricated a vision chip for edge detection with a
pixel array by using 0.35
standard complementary metal-oxide-semiconductor (CMOS) technology. The designed vision chip is based on a retinal structure with a resistive network to improve the speed of operation. To improve the quality of final edge images, we applied a saturating resistive circuit to the resistive network. The light-adaptation mechanism of the edge detection circuit was quantitatively analyzed using a simple model of the saturating resistive element. To verify improvement, we compared the simulation results of the proposed circuit to the results of previous circuits.
Low-Voltage Current-Sensing CMOS Interface Circuit for Piezo-Resistive Pressure Sensor
Thanachayanont, Apinunt ; Sangtong, Suttisak ;
ETRI Journal, volume 29, issue 1, 2007, Pages 70~78
A new low-voltage CMOS interface circuit with digital output for piezo-resistive transducer is proposed. An input current sensing configuration is used to detect change in piezo-resistance due to applied pressure and to allow low-voltage circuit operation. A simple 1-bit first-order delta-sigma modulator is used to produce an output digital bitstream. The proposed interface circuit is realized in a 0.35
CMOS technology and draws less than 200
from a single 1.5 V power supply voltage. Simulation results show that the circuit can achieve an equivalent output resolution of 9.67 bits with less than 0.23% non-linearity error.
Low-Power-Adaptive MC-CDMA Receiver Architecture
Hasan, Mohd. ; Arslan, Tughrul ; Thompson, John S. ;
ETRI Journal, volume 29, issue 1, 2007, Pages 79~88
This paper proposes a novel concept of adjusting the hardware size in a multi-carrier code division multiple access (MC-CDMA) receiver in real time as per the channel parameters such as delay spread, signal-to-noise ratio, transmission rate, and Doppler frequency. The fast Fourier transform (FFT) or inverse FFT (IFFT) size in orthogonal frequency division multiplexing (OFDM)/MC-CDMA transceivers varies from 1024 points to 16 points. Two low-power reconfigurable radix-4 256-point FFT processor architectures are proposed that can also be dynamically configured as 64-point and 16-point as per the channel parameters to prove the concept. By tailoring the clock of the higher FFT stages for longer FFTs and switching to shorter FFTs from longer FFTs, significant power saving is achieved. In addition, two 256 sub-carrier MC-CDMA receiver architectures are proposed which can also be configured for 64 sub-carriers in real time to prove the feasibility of the concept over the whole receiver.
Prediction of Gain Expansion and Intermodulation Performance of Nonlinear Amplifiers
Abuelma'atti, Muhammad Taher ;
ETRI Journal, volume 29, issue 1, 2007, Pages 89~94
A mathematical model for the input-output characteristic of an amplifier exhibiting gain expansion and weak and strong nonlinearities is presented. The model, basically a Fourier-series function, can yield closed-form series expressions for the amplitudes of the output components resulting from multisinusoidal input signals to the amplifier. The special case of an equal-amplitude two-tone input signal is considered in detail. The results show that unless the input signal can drive the amplifier into its nonlinear region, no gain expansion or minimum intermodulation performance can be achieved. For sufficiently large input amplitudes that can drive the amplifier into its nonlinear region, gain expansion and minimum intermodulation performance can be achieved. The input amplitudes at which these phenomena are observed are strongly dependent on the amplifier characteristics.
Sidelobe Reduction of Low-Profile Array Antenna Using a Genetic Algorithm
Son, Seong-Ho ; Park, Ung-Hee ;
ETRI Journal, volume 29, issue 1, 2007, Pages 95~98
A low-profile phased array antenna with a low sidelobe was designed and fabricated using a genetic algorithm (GA). The subarray distances were optimized by GA with chromosomes of 78 bits, a population of 100, a crossover probability of 0.9, and a mutation probability of 0.005. The array antenna has 24 subarrays in 14 rows, and is designed as a mobile terminal for Ku-band satellite communication. The sidelobe level was suppressed by 6.5 dB after optimization, compared to the equal spacing between subarrays. The sidelobe level was verified from the far-field pattern measurement by using the fabricated array antenna with optimized distance.
Improved Channel Level Difference Quantization for Spatial Audio Coding
Kim, Kwang-Ki ; Beack, Seung-Kwon ; Seo, Jeong-Il ; Jang, Dae-Young ; Hahn, Min-Soo ;
ETRI Journal, volume 29, issue 1, 2007, Pages 99~102
The channel level difference (CLD) is a main parameter in the reference model 0 (RM0) for MPEG Surround. Nevertheless, the CLD quantization method in the RM0 has problems such as the lack of theoretical background and inappropriate quantization levels. In this letter, a new CLD quantization method is proposed based on the virtual source location information which has strength in the quantization process. From experimental results, it is confirmed that the proposed scheme greatly reduces the quantization distortions measured in dB and degrees without any additional complexity.
Extended Pilot-Based Coding for Lossless Bit Rate Reduction of MPEG Surround
Pang, Hee-Suk ; Lim, Jae-Hyun ; Oh, Hyen-O ;
ETRI Journal, volume 29, issue 1, 2007, Pages 103~106
Pilot-based coding (PBC), which is used for lossless bit rate reduction of audio coding, has been recently proposed for MPEG Surround. We propose extended PBC for further lossless bit rate reduction of MPEG Surround. Extended PBC selects the number of pilots depending on the parameter band number and the type of spatial parameter. It then encodes the pilots and the relevant difference data. Experiments show that extended PBC is more effective than the original PBC, especially for high bit rate modes, with a negligible complexity increase on the decoder side.
Multilevel Location Trigger in Distributed Mobile Environments for Location-Based Services
Min, Kyoung-Wook ; Nam, Kwang-Woo ; Kim, Ju-Wan ;
ETRI Journal, volume 29, issue 1, 2007, Pages 107~109
In location-based services, most trigger technologies have been implemented on the server side by periodically requesting the locations of mobile phones from mobile network servers. However, bottlenecks and communication interruptions occur when the servers are overloaded by trigger requests. In this letter, we propose a new multilevel location trigger specification which distributes the event detecting role to mobile phones and redesigns the location triggering into a multilevel step. Our suggested location trigger specification can reduce bottlenecks caused by triggers in a mobile core network and reduce power consumption caused by embedded GPS devices in mobile phones.
Design of Robust Detector with Noise Variance Estimation Censoring Input Signals over AWGN
Lee, Hyeon-Cheol ; Halverson, Don R. ;
ETRI Journal, volume 29, issue 1, 2007, Pages 110~112
As an alternative to the classic linear detector which only assumes noise variance, a new robust detector with noise variance estimation censoring input signals over AWGN is proposed. The results demonstrate that analytic detection probability matches the simulation results for the linear detector and that the new robust detector shows better performance than the linear detector when the number of samples increases.
On the Handover Performance of a Tri-threshold Bandwidth Reservation CAC Scheme
Tung, Hoi Yan ; Tsang, Kim Fung ; Lee, Lap To ; Lam, Ka Lun ; Sun, Yu Ting ; Kwan, Shiu Keung Ronald ; Chan, Sammy ;
ETRI Journal, volume 29, issue 1, 2007, Pages 113~115
A dynamic tri-threshold call admission control scheme has been developed. This scheme supports voice, data, and multimedia services and it complies with the universal mobile telecommunications system. The performance of the proposed scheme is evaluated under varying handover rates. The QoS performance-including channel utilization, call dropping probability, and blocking probability-is investigated. The performance of the developed scheme is found to be encouraging.
Simultaneous Burst and Burst Control Packet Transmission Protocol for Optical Burst Switching Ring Networks
Park, Joon-Pyo ; Lee, Man-Seop ;
ETRI Journal, volume 29, issue 1, 2007, Pages 116~119
In this letter, we design a collision resolution protocol for optical burst switching ring networks to avoid burst collision. We define the offset time condition for no burst transmission collision and manage the free time list of nodes for no burst reception collision. In order to improve the throughput, we use a fiber delay line, void-filling, and void-compression. This protocol does not require any additional procedures for bandwidth reservation such as centralized assignment of bandwidth, lightpath setup of WDM ring networks, or token capturing for the burst transmission. The simulation results show that the proposed protocol can achieve high throughput while saving 70% of wavelengths when compared to round robin with random selection, round robin with persistent, and round robin with non-persistent with only destination delay.
Traffic Aided Uplink Opportunistic Scheduling with QoS Support in Multiservice CDMA Networks
Liao, Dan ; Li, Lemin ;
ETRI Journal, volume 29, issue 1, 2007, Pages 120~123
In this letter, we address the problem of resource allocation with efficiency and quality of service (QoS) support in uplink for a wireless CDMA network supporting real-time (RT) and non-realtime (NRT) communication services. For RT and NRT users, there are different QoS requirements. We introduce and describe a new scheme, namely, traffic aided uplink opportunistic scheduling (TAUOS). While guaranteeing the different QoS requirements, TAUOS exploits the channel condition to improve system throughput. In TAUOS, the cross-layer information, file size information, is used to improve fairness for NRT users. Extensive simulation results show that our scheme can achieve high system throughput in uplink wireless CDMA systems, while guaranteeing QoS requirements.
Radiation Effects of Proton Particles in Memory Devices
Lho, Young-Hwan ; Kim, Ki-Yup ;
ETRI Journal, volume 29, issue 1, 2007, Pages 124~126
In this letter, we study the impact of single event upsets (SEUs) in space or defense electronic systems which use memory devices such as EEPROM, and SRAM. We built a microcontroller test board to measure the effects of protons on electronic devices at various radiation levels. We tested radiation hardening at beam current, and energy levels, measured the phenomenon of SEUs, and addressed possible reasons for SEUs.