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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 28, Issue 6 - Dec 2006
Volume 28, Issue 5 - Oct 2006
Volume 28, Issue 4 - Aug 2006
Volume 28, Issue 3 - Jun 2006
Volume 28, Issue 2 - Apr 2006
Volume 28, Issue 1 - Feb 2006
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Design and Implementation of 4S-Van: A Mobile Mapping System
Lee, Seung-Yong ; Choi, Kyoung-Ho ; Joo, In-Hak ; Cho, Seong-Ik ; Park, Jong-Hyun ;
ETRI Journal, volume 28, issue 3, 2006, Pages 265~274
Recent advances in positioning and photogrammetry technologies have made it possible to build a mobile mapping system (MMS) that can obtain 3D coordinates of geographic objects from stereo images recorded from a moving vehicle. In this paper, we present a design and detailed implementation of an MMS called a 4S-Van. Furthermore, we present four issues that have made major contributions to the performance of an MMS: 1) CCD camera calibration, 2) GPS signal condition, 3) integrating a GPS, inertial navigation system (INS), distance measurement indicator (DMI), and CCD cameras, and 4) the orientation angle of CCD cameras. In the experimental results, the performance of an MMS was analyzed for each component, giving an idea of how to effectively design and integrate each component in developing an MMS to get a maximal accuracy of 3D coordinates.
A Simple Scheme for Jitter Reduction in Phase-Differential Carrier Frequency Recovery Loop
Lim, Hyoung-Soo ; Kwon, Dong-Seung ;
ETRI Journal, volume 28, issue 3, 2006, Pages 275~281
A very simple and efficient scheme for jitter reduction is proposed for a carrier frequency recovery loop using phase differential frequency estimation, which estimates the current frequency offset based on the difference of the average phases of two successive intervals. Analytical and numerical results presented in this paper show that by simply overlapping the observation intervals by half for frequency offset estimations, both the steady-state and transient performances can be improved. The proposed scheme does not require any additional hardware circuitry, but results in improved performance even with reduced complexity.
An Adaptive Hot-Spot Operating Scheme for OFDMA Downlink Systems in Vertically Overlaid Cellular Architecture
Kim, Nak-Myeong ; Choi, Hye-Sun ; Chung, Hee-Jeong ;
ETRI Journal, volume 28, issue 3, 2006, Pages 282~290
In vertically overlaid cellular systems, a temporary traffic concentration can occur in a hot-spot area, and this adversely affects overall system capacity. In this paper, we develop an adaptive hot-spot operating scheme (AHOS) to mitigate the negative effects from the nonuniform distribution of user location and the variation in the mixture of QoS requirements in orthogonal frequency division multiple access downlink systems. Here, the base station in a macrocell can control the operation of picocells within the cell, and turns them on or off according to the system overload estimation function. In order to determine whether the set of picocells is turned on or off, we define an AHOS gain index that describes the number of subcarriers saved to the macrocell by turning a specific picocell on. For initiating the picocell OFF procedure, we utilize the changes in traffic concentration and co-channel interference to the neighboring cells. According to computer simulation, the AHOS has been proved to have maximize system throughput while maintaining a very low QoS outage probability under various system scenarios in both a single-cell and multi-cell environments.
General Log-Likelihood Ratio Expression and Its Implementation Algorithm for Gray-Coded QAM Signals
Kim, Ki-Seol ; Hyun, Kwang-Min ; Yu, Chang-Wahn ; Park, Youn-Ok ; Yoon, Dong-Weon ; Park, Sang-Kyu ;
ETRI Journal, volume 28, issue 3, 2006, Pages 291~300
A simple and general bit log-likelihood ratio (LLR) expression is provided for Gray-coded rectangular quadrature amplitude modulation (R-QAM) signals. The characteristics of Gray code mapping such as symmetries and repeated formats of the bit assignment in a symbol among bit groups are applied effectively for the simplification of the LLR expression. In order to reduce the complexity of the max-log-MAP algorithm for LLR calculation, we replace the mathematical max or min function of the conventional LLR expression with simple arithmetic functions. In addition, we propose an implementation algorithm of this expression. Because the proposed expression is very simple and constructive with some parameters reflecting the characteristic of the Gray code mapping result, it can easily be implemented, providing an efficient symbol de-mapping structure for various wireless applications.
Fano Decoding with Timeout: Queuing Analysis
Pan, W. David ; Yoo, Seong-Moo ;
ETRI Journal, volume 28, issue 3, 2006, Pages 301~310
In mobile communications, a class of variable-complexity algorithms for convolutional decoding known as sequential decoding algorithms is of interest since they have a computational time that could vary with changing channel conditions. The Fano algorithm is one well-known version of a sequential decoding algorithm. Since the decoding time of a Fano decoder follows the Pareto distribution, which is a heavy-tailed distribution parameterized by the channel signal-to-noise ratio (SNR), buffers are required to absorb the variable decoding delays of Fano decoders. Furthermore, since the decoding time drawn by a certain Pareto distribution can become unbounded, a maximum limit is often employed by a practical decoder to limit the worst-case decoding time. In this paper, we investigate the relations between buffer occupancy, decoding time, and channel conditions in a system where the Fano decoder is not allowed to run with unbounded decoding time. A timeout limit is thus imposed so that the decoding will be terminated if the decoding time reaches the limit. We use discrete-time semi-Markov models to describe such a Fano decoding system with timeout limits. Our queuing analysis provides expressions characterizing the average buffer occupancy as a function of channel conditions and timeout limits. Both numerical and simulation results are provided to validate the analytical results.
Terminal-Assisted Hybrid MAC Protocol for Differentiated QoS Guarantee in TDMA-Based Broadband Access Networks
Hong, Seung-Eun ; Kang, Chung-Gu ; Kwon, O-Hyung ;
ETRI Journal, volume 28, issue 3, 2006, Pages 311~319
This paper presents a terminal-assisted frame-based packet reservation multiple access (TAF-PRMA) protocol, which optimizes random access control between heterogeneous traffic aiming at more efficient voice/data integrated services in dynamic reservation TDMA-based broadband access networks. In order to achieve a differentiated quality-of-service (QoS) guarantee for individual service plus maximal system resource utilization, TAF-PRMA independently controls the random access parameters such as the lengths of the access regions dedicated to respective service traffic and the corresponding permission probabilities, on a frame-by-frame basis. In addition, we have adopted a terminal-assisted random access mechanism where the voice terminal readjusts a global permission probability from the central controller in order to handle the 'fair access' issue resulting from distributed queuing problems inherent in the access network. Our extensive simulation results indicate that TAF-PRMA achieves significant improvements in terms of voice capacity, delay, and fairness over most of the existing medium access control (MAC) schemes for integrated services.
SVM-Based Speaker Verification System for Match-on-Card and Its Hardware Implementation
Choi, Woo-Yong ; Ahn, Do-Sung ; Pan, Sung-Bum ; Chung, Kyo-Il ; Chung, Yong-Wha ; Chung, Sang-Hwa ;
ETRI Journal, volume 28, issue 3, 2006, Pages 320~328
Using biometrics to verify a person's identity has several advantages over the present practice of personal identification numbers (PINs) and passwords. To gain maximum security in a verification system using biometrics, the computation of the verification as well as the storing of the biometric pattern has to take place in a smart card. However, there is an open issue of integrating biometrics into a smart card because of its limited resources (processing power and memory space). In this paper, we propose a speaker verification algorithm using a support vector machine (SVM) with a very few features, and implemented it on a 32-bit smart card. The proposed algorithm can reduce the required memory space by a factor of more than 100 and can be executed in real-time. Also, we propose a hardware design for the algorithm on a field-programmable gate array (FPGA)-based platform. Based on the experimental results, our SVM solution can provide superior performance over typical speaker verification solutions. Furthermore, our FPGA-based solution can achieve a speed-up of 50 times over a software-based solution.
A Novel Shared Segment Protection Algorithm for Multicast Sessions in Mesh WDM Networks
Lu, Cai ; Luo, Hongbin ; Wang, Sheng ; Li, Lemin ;
ETRI Journal, volume 28, issue 3, 2006, Pages 329~336
This paper investigates the problem of protecting multicast sessions in mesh wavelength-division multiplexing (WDM) networks against single link failures, for example, a fiber cut in optical networks. First, we study the two characteristics of multicast sessions in mesh WDM networks with sparse light splitter configuration. Traditionally, a multicast tree does not contain any circles, and the first characteristic is that a multicast tree has better performance if it contains some circles. Note that a multicast tree has several branches. If a path is added between the leave nodes on different branches, the segment between them on the multicast tree is protected. Based the two characteristics, the survivable multicast sessions routing problem is formulated into an Integer Linear Programming (ILP). Then, a heuristic algorithm, named the adaptive shared segment protection (ASSP) algorithm, is proposed for multicast sessions. The ASSP algorithm need not previously identify the segments for a multicast tree. The segments are determined during the algorithm process. Comparisons are made between the ASSP and two other reported schemes, link disjoint trees (LDT) and shared disjoint paths (SDP), in terms of blocking probability and resource cost on CERNET and USNET topologies. Simulations show that the ASSP algorithm has better performance than other existing schemes.
Dependency Structure Applied to Language Modeling for Information Retrieval
Lee, Chang-Ki ; Lee, Gary Geun-Bae ; Jang, Myung-Gil ;
ETRI Journal, volume 28, issue 3, 2006, Pages 337~346
In this paper, we propose a new language model, namely, a dependency structure language model, for information retrieval to compensate for the weaknesses of unigram and bigram language models. The dependency structure language model is based on the first-order dependency model and the dependency parse tree generated by a linguistic parser. So, long-distance dependencies can be naturally captured by the dependency structure language model. We carried out extensive experiments to verify the proposed model, where the dependency structure model gives a better performance than recently proposed language models and the Okapi BM25 method, and the dependency structure is more effective than unigram and bigram in language modeling for information retrieval.
Characteristic Variation of 3-D Solenoid Embedded Inductors for Wireless Communication Systems
Shin, Dong-Wook ; Oh, Chang-Hoon ; Kim, Kil-Han ; Yun, Il-Gu ;
ETRI Journal, volume 28, issue 3, 2006, Pages 347~354
The characteristic variation of 3-dimensional (3-D) solenoid-type embedded inductors is investigated. Four different structures of a 3-D inductor are fabricated by using a low-temperature co-fired ceramic (LTCC) process, and their s-parameters are measured between 50 MHz and 5 GHz. The circuit model parameters of each building block are optimized and extracted using the partial element equivalent circuit method and an HSPICE circuit simulator. Based on the model parameters, the characteristics of the test structures such as self-resonant frequency, inductance, and quality (Q) factor are analyzed, and predictive modeling is applied to the structures composed of a combination of the modeled building blocks. In addition, characteristic variations of the 3-D inductors with different structures using extracted building blocks are also investigated. This approach can provide a characteristic estimation of 3-D solenoid embedded inductors for structural variations.
A New Approach for Built-in Self-Test of 4.5 to 5.5 GHz Low-Noise Amplifiers
Ryu, Jee-Youl ; Noh, Seok-Ho ;
ETRI Journal, volume 28, issue 3, 2006, Pages 355~363
This paper presents a low-cost RF parameter estimation technique using a new RF built-in self-test (BIST) circuit and efficient DC measurement for 4.5 to 5.5 GHz low noise amplifiers (LNAs). The BIST circuit measures gain, noise figure, input impedance, and input return loss for an LNA. The BIST circuit is designed using
SiGe technology. The test technique utilizes input impedance matching and output DC voltage measurements. The technique is simple and inexpensive.
Transmission of Traffic Information Using a Terrestrial Digital Multimedia Broadcasting System
Cho, Sam-Mo ; Kim, Geon ; Jeong, Young-Ho ; Ahn, Chung-Hyun ; Lee, Soo-In ; Lee, Hyuck-Jae ;
ETRI Journal, volume 28, issue 3, 2006, Pages 364~366
This letter introduces an efficient transmission of traffic information through a terrestrial digital multimedia broadcasting system, which is a multimedia and mobility empowered option of the European digital audio broadcasting system. By adapting Korean characteristic traffic information into the transport protocol expert group messages in the traffic information delivery, a highly efficient traffic information system was implemented and tested in Korea.
Object Tracking for a Video Sequence from a Moving Vehicle: A Multi-modal Approach
Hwang, Tae-Hyun ; Cho, Seong-Ick ; Park, Jong-Hyun ; Choi, Kyoung-Ho ;
ETRI Journal, volume 28, issue 3, 2006, Pages 367~370
This letter presents a multi-modal approach to tracking geographic objects such as buildings and road signs in a video sequence recorded from a moving vehicle. In the proposed approach, photogrammetric techniques are successfully combined with conventional tracking methods. More specifically, photogrammetry combined with positioning technologies is used to obtain 3-D coordinates of chosen geographic objects, providing a search area for conventional feature trackers. In addition, we present an adaptive window decision scheme based on the distance between chosen objects and a moving vehicle. Experimental results are provided to show the robustness of the proposed approach.
Total Resource Requirements-Based Priority Queuing Scheme for DS/CDMA Cellular Networks
Piao, Shiquan ; Park, Jae-Won ; Park, Yong-Wan ;
ETRI Journal, volume 28, issue 3, 2006, Pages 371~374
We propose and analyze a priority queuing scheme that gives priority in the same class of calls according to their total resource requirements (TRRs). The proposed scheme gives a higher priority to the calls that have a lower TRR over the calls that have a higher TRR. The numerical results show that the proposed priority queuing scheme provides better performance than the traditional queuing schemes in call blocking probability.
Compromise-Resistant Pairwise Key Establishments for Mobile Ad hoc Networks
Wang, Gi-Cheol ; Cho, Gi-Hwan ;
ETRI Journal, volume 28, issue 3, 2006, Pages 375~378
This letter presents a pairwise key establishment scheme that is robust against the compromise of nodes in mobile ad hoc networks. Each node establishes local keys with its neighbor nodes that are at most three hops away at network boot-up time. When any two nodes establish a pairwise key, they receive the secret information from the nodes on the route between them, and construct the pairwise key using the secret information. Here, the local keys are utilized by the nodes on the route to send the secret information securely. The simulation results have proven that the proposed scheme provides better security than the key pre-distribution-based scheme.
Reconfigurable Microstrip Patch Antenna with Switchable Polarization
Chung, Kyung-Ho ; Nam, Yong-Sik ; Yun, Tae-Yeoul ; Choi, Jae-Hoon ;
ETRI Journal, volume 28, issue 3, 2006, Pages 379~382
A novel reconfigurable microstrip patch antenna with frequency and polarization diversities is proposed. A U-slot is incorporated into a square patch, and a PIN diode is utilized to switch the slot on and off, which realizes the frequency diversity characteristic. The polarization diversities among linear polarization (LP), right-hand circular polarization (RHCP), and left-hand circular polarization (LHCP) are also obtained by switching three PIN diodes on the slot and the truncating corners of a square patch on and off. The antenna design and experimental results are presented.
Open-Ended Two-Strip Meander-Line Antenna for RFID Tags
Son, Hae-Won ; Choi, Gil-Young ; Pyo, Cheol-Sig ;
ETRI Journal, volume 28, issue 3, 2006, Pages 383~385
A new meander-line antenna consisting of two open-ended strips is proposed for a compact and broadband UHF radio frequency identification tag. An equivalent circuit model for the proposed antenna is derived and used to perform a simple and wideband impedance match to an arbitrary complex impedance of a tag chip without any additional matching network. The performance of the proposed antenna is validated by comparing calculated and measured results, which show good agreement.
Monolithic SiGe HBT Feedforward Variable Gain Amplifiers for 5 GHz Applications
Kim, Chang-Woo ;
ETRI Journal, volume 28, issue 3, 2006, Pages 386~388
Monolithic SiGe heterojunction bipolar transistor (HBT) variable gain amplifiers (VGAs) with a feedforward configuration have been newly developed for 5 GHz applications. Two types of the feedforward VGAs have been made: one using a coupled-emitter resistor and the other using an HBT-based current source. At 5.2 GHz, both of the VGAs achieve a dynamic gain-control range of 23 dB with a control-voltage range from 0.4 to 2.6 V. The gain-tuning sensitivity is 90 mV/dB. At
= 2.4 V, the 1 dB compression output power,
, and dc bias current are 0 dBm and 59 mA in a VGA with an emitter resistor and -1.8 dBm and 71mA in a VGA with a constant current source, respectively.
A Laterally-Driven Bistable Electromagnetic Microrelay
Ko, Jong-Soo ; Lee, Min-Gon ; Han, Jeong-Sam ; Go, Jeung-Sang ; Shin, Bo-Sung ; Lee, Dae-Sik ;
ETRI Journal, volume 28, issue 3, 2006, Pages 389~392
In this letter, a laterally-driven bistable electromagnetic microrelay is designed, fabricated, and tested. The proposed microrelay consists of a pair of arch-shaped leaf springs, a shuttle, and a contact bar made from silicon, low temperature oxide (LTO), and gold composite materials. Silicon-on-insulator wafers are used for electrical isolation and releasing of the moving microstructures. The high-aspect-ratio microstructures are fabricated using a deep reactive ion etching (DRIE) process. The tandem-typed leaf springs with a silicon/gold composite layer enhance the mechanical performances while reducing the electrical resistance. A permanent magnet is attached at the bottom of the silicon substrate, resulting in the generation of an external magnetic field in the direction vertical to the surface of the silicon substrate. The leaf springs show bistable characteristics. The resistance of the pair of leaf springs was
, and the contact resistance was
. The relay was operated at
New Impedance Matching Scheme for 60 GHz Band Electro-Absorption Modulator Modules
Choi, Kwang-Seong ; Chung, Yong-Duck ; Kang, Young-Shik ; Jun, Dong-Suk ; Ahn, Byoung-Tae ; Moon, Jong-Tae ; Kim, Je-Ha ;
ETRI Journal, volume 28, issue 3, 2006, Pages 393~396
This letter proposes a new impedance matching scheme of a traveling wave electro-absorption modulator (TWEAM) module for a 60 GHz band radio-over-fiber (ROF) link. A microstrip band pass filter (BPF) was used to achieve impedance matching at the 60 GHz band, and termination resistance was carefully designed to obtain an input impedance close to
. Also, a bias circuit for the device was designed in the module. The measured return loss and frequency response show that the modulator module observes the characteristics of a filter without the need of a further tuning process.
An Ameliorated Design Method of ML-AHB BusMatrix
Hwang, Soo-Yun ; Jhang, Kyoung-Sun ; Park, Hyeong-Jun ; Bae, Young-Hwan ; Cho, Han-Jin ;
ETRI Journal, volume 28, issue 3, 2006, Pages 397~400
The multi-layer advanced high-performance bus (ML-AHB) BusMatrix proposed by ARM is an excellent architecture for applying embedded systems with low power. However, there is one clock cycle delay for each master in the ML-AHB BusMatrix of the advanced microcontroller bus architecture (AMBA) design kit (ADK) whenever a master starts new transactions or changes the slave layers. In this letter, we propose an improved design method to remove the one clock cycle delay in the ML-AHB BusMatrix of an ADK. We also remarkably reduce the total area and power consumption of the ML-AHB BusMatrix of an ADK with the elimination of the heavy input stages.
A Novel Log-Domain First-Order Multifunction Filter
Kircay, Ali ; Cam, Ugur ;
ETRI Journal, volume 28, issue 3, 2006, Pages 401~404
A new log-domain first-order multifunction filter is proposed in this letter. The proposed filter is systematically derived using the state-space synthesis procedure from a corresponding block diagram. It provides low-pass (LP), high-pass (HP), and all-pass (AP) responses simultaneously for a single input signal. The filter circuit has a very simple structure since it uses only bipolar junction transistors (BJTs) and a grounded capacitor. It can be electronically tuned by changing an external current. The filter has a greater bandwidth due to its inherent current-mode and log-domain operations. PSPICE simulations are given to confirm the theoretical analysis.
Postal RFID Application Model and Performance
Park, Jeong-Hyun ; Park, Jong-Heung ;
ETRI Journal, volume 28, issue 3, 2006, Pages 405~408
In this letter, we suggest a postal RFID application model and system architecture that can be used for real-time trace and tracking system implementation of parcel processing and pallet management. This letter also shows the tag recognition performance of parcels and pallets by speed and mounting tag materials such as cans, water, and paper using an implemented postal RFID system for postal logistics.