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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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The Journal of Korean Institute of Communications and Information Sciences
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The Korean Institute of Communications and Information Sciences
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Volume & Issues
Volume 35, Issue 12C - Dec 2010
Volume 35, Issue 12B - Dec 2010
Volume 35, Issue 12A - Dec 2010
Volume 35, Issue 11C - Nov 2010
Volume 35, Issue 11B - Nov 2010
Volume 35, Issue 11A - Nov 2010
Volume 35, Issue 10C - Oct 2010
Volume 35, Issue 10B - Oct 2010
Volume 35, Issue 10A - Oct 2010
Volume 35, Issue 9C - Sep 2010
Volume 35, Issue 9B - Sep 2010
Volume 35, Issue 9A - Sep 2010
Volume 35, Issue 8C - Aug 2010
Volume 35, Issue 8B - Aug 2010
Volume 35, Issue 8A - Aug 2010
Volume 35, Issue 7C - Jul 2010
Volume 35, Issue 7B - Jul 2010
Volume 35, Issue 7A - Jul 2010
Volume 35, Issue 6C - Jun 2010
Volume 35, Issue 6B - Jun 2010
Volume 35, Issue 6A - Jun 2010
Volume 35, Issue 5C - May 2010
Volume 35, Issue 5B - May 2010
Volume 35, Issue 5A - May 2010
Volume 35, Issue 4C - Apr 2010
Volume 35, Issue 4B - Apr 2010
Volume 35, Issue 4A - Apr 2010
Volume 35, Issue 3C - Mar 2010
Volume 35, Issue 3B - Mar 2010
Volume 35, Issue 3A - Mar 2010
Volume 35, Issue 2C - Feb 2010
Volume 35, Issue 2B - Feb 2010
Volume 35, Issue 2A - Feb 2010
Volume 35, Issue 1C - Jan 2010
Volume 35, Issue 1B - Jan 2010
Volume 35, Issue 1A - Jan 2010
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Energy Efficient Routing Scheme for Wireless Sensor Networks
Kim, Dong-Sik ; Kim, Sung-Wook ;
The Journal of Korean Institute of Communications and Information Sciences, volume 35, issue 5A, 2010, Pages 417~422
In this paper, we propose a new routing scheme based on the multiple layer routing strategy. This algorithm can guarantee the required QoS while maximizing energy efficiency in wireless sensor networks. The principle contributions of this work are its simplicity, scalability and responsiveness to current network situations. Simulation results indicate the superior performance of our proposed algorithm, while other existing scheme cannot offer such an attractive performance balance.
Efficient Detection Scheme for Turbo Coded QO-STBC Schemes
Park, Un-Hee ; Oh, Dae-Sub ; Kim, Young-Min ; Kim, Soo-Young ;
The Journal of Korean Institute of Communications and Information Sciences, volume 35, issue 5A, 2010, Pages 423~430
The performances of turbo-coded space-time block coding (STBC) schemes are subject to how soft decision detection (SDD) information are generated from the STBC decoder. For this reason, we have to pay particular attention to estimation of SDD. In this paper, we evaluate the performance of a turbo coded STBC scheme depending on the accuracy of the SDD. Recently, a new quasi orthogonal STBC (QO-STBC) scheme using a noise whitened filter was proposed in order to reduce noise enhancing effect of zero forcing detection process. This QO-STBC scheme was proven to be efficient in computational complexity compared to the other conventional QO-STBC schemes. In this paper, we first present detailed mathematical analysis on the noise whitened QO-STBC scheme, and by using the result we propose the optimum SDD method.
Performance of Multiple-Relay Cooperative Communication Networks under Soft-Decision-and-Forward Protocol
Song, Kyoung-Young ; No, Jong-Seon ; Kim, Tae-Guen ; Sung, Joon-Hyun ; Rim, Min-Joong ; Lim, Dae-Woon ;
The Journal of Korean Institute of Communications and Information Sciences, volume 35, issue 5A, 2010, Pages 431~439
In this paper, multiple-relay cooperative communication network with multiple antennas is considered. Applying the soft-decision-and-forward protocol to this system, pairwise error probability(PEP) is derived and then symbol error rate(SER) is also calculated. However, in general, signals are transmitted through the orthogonal channel in the multiple-relay cooperative communication network for the prevention of interference, which is inefficient in terms of the throughput. For the improvement of throughput, the relay selection is considered, where the relay having the maximum instantaneous end-to-end signal-to-noise ratio is chosen. Performance of the system is analyzed in terms of PEP and SER. As the number of the relay increases, relay selection method outperforms the conventional multiple-relay transmission system where all relays participate in the second time slot.
Human Body Communication Using Chirp Spread Spectrum Modulation
Kim, Kyung-Chul ; Jeon, Myeong-Woon ; Kim, Ki-Hyun ; Lee, Jung-Woo ; Nam, Sang-Wook ;
The Journal of Korean Institute of Communications and Information Sciences, volume 35, issue 5A, 2010, Pages 440~446
Convergence of IT and BT is considered in many area, especially in medical care industry. The example of this trend is a capsule endoscope. But in a capsule endoscope, communication through human body has a few restrictions. At first, the transmit power should be limited not to have a bad effect on human organs and for the battery capacity. Second, the channel characteristic of human body has not been examined exactly. Third, general modulation / demodulation techniques which require a channel estimation cannot be used because of battery limit. There also may be a lot of interference signals because a capsule endoscope uses UWB bandwidth. In this paper, we introduce Chirp Spread Spectrum Differential Binary Phase Shift Keying(CSS-DBPSK) and propose Chirp Spread Spectrum On-Off Keying(CSS-OOK) which don't require a channel estimation and robust to interference signals. Using CSS-DBPSK or CSS-OOK, we can get 5 dB or 2~3 dB of Eb/N0 gain at 10-5 target BER. And if there are interference signals, those gains of CSS-DBPSK and CSS-OOK are increased.
Resource Allocation Scheme for Ensuring QoS of Heterogeneous Traffic in OFDMA System
Gwak, Yong-Su ; Koh, Chung Ha ; Kim, Young-Yong ;
The Journal of Korean Institute of Communications and Information Sciences, volume 35, issue 5A, 2010, Pages 447~451
We propose an advanced BMPA (balanced multimedia packet allocation) scheme. The proposed scheme considers the optimal resource allocation problem in OFDMA system. When NRT (non-real time), RT (real time), multicast packets arrive at the same time in OFDMA system, the advanced BMPA chooses the best sub-carrier as a multicast channel for multicast packets, gives more weight to RT packets and multicast packets than NRT packets and allocates sub-carriers according to the total weight sum of packets in each user. With simulation results, this paper shows that the advanced BMPA scheme ensures QoS (long-term system throughput and multimedia packet delay) in heterogeneous traffic compared with multicast MU-WF (multi-user water-filling) and BMPA schemes.
SIR based Beam Switching in Distributed Controlled Cellular Systems
Kim, Dong-Hee ;
The Journal of Korean Institute of Communications and Information Sciences, volume 35, issue 5A, 2010, Pages 452~456
SIR based beam switching in distributed controlled cellular systems is proposed to reduce intercell interference. Compared with Random beam switching that beam switching pattern is randomly selected and cannot avoid beam collision between neighboring cell, SIR based beam switching update its switching pattern based on SIR report from mobile. Neighboring cells independently update their switching patterns and the updated patterns converge to the patterns that minimize beam collision. We shows SIR base beam switching has 20% gain compared with random beam switching in two neighboring cell model.
A Latency-Secured Algorithm for Delay-Sensitive Large-Scale Sensor Networks
Hossen, Monir ; Kim, Ki-Doo ; Park, Young-Il ;
The Journal of Korean Institute of Communications and Information Sciences, volume 35, issue 5A, 2010, Pages 457~465
When a sensor network is used for monitoring environments in large area or transmitting information in a u-City the number of nodes becomes very large. One of the problems with this application is the increased time delay, especially in reverse direction. In this paper, we propose a new algorithm that can minimize the latency of reverse packet in large sensor network. Analysis shows that the proposed scheme can reduce the latency by more than 90% when compared to Zigbee, while the energy consumption is maintained.
A Branch and Bound Algorithm to Find a Routing Tree Having Minimum Wiener Index in Sensor Networks with High Mobile Base Node
Kang, Seung-Ho ; Kim, Ki-Young ; Lee, Woo-Young ; Song, Iick-Ho ; Jung, Min-A ; Lee, Seong-Ro ;
The Journal of Korean Institute of Communications and Information Sciences, volume 35, issue 5A, 2010, Pages 466~473
Several protocols which are based on tree topology to guarantee the important metrics such as energy efficiency in sensor networks have been proposed. However, studies on the effect of topologies in sensor networks, where base node has a high mobility, are very few. In this paper, we propose a minimum Wiener index tree as a suitable topology to the wireless sensor networks with high mobile base node. The minimum Wiener index spanning tree problem which aims to find a tree with minimum Wiener index from a given weighted graph was proved to be NP-hard. We designed a branch and bound algorithm for this problem. To evaluate the performance of proposed tree, the comparisons with minimum spanning tree in terms of transmission distance, energy consumption during one round, and network lifetime was performed by simulations. Our proposed tree outperformed in transmission distance and energy efficiency but underperformed in lifetime.
An Effective Cross Layer-based Multimedia Transmission Algorithm over Multi-hop Mobile Ad Hoc Network
Lee, Gyeong-Cheol ; Kim, Wan ; Song, Hwang-Jun ;
The Journal of Korean Institute of Communications and Information Sciences, volume 35, issue 5A, 2010, Pages 474~481
In this paper, we present an effective cross layer-based video transmission algorithm over multi-hop mobile ad hoc networks. The proposed algorithm selects the most efficient PHY mode of wireless LAN multi-rate service at each node in a distributed way based on the available information at application, MAC, and physical layers in order to minimize end-to-end delay and maintain packet loss rate in tolerable range at the receiver. Finally, experimental results are provided to show superior performance of the proposed algorithm.
A Fully Integrated Low-IF Receiver using Poly Phase Filter for VHF Applications
Kim, Seong-Do ; Park, Dong-Woon ; Oh, Seung-Hyeub ;
The Journal of Korean Institute of Communications and Information Sciences, volume 35, issue 5A, 2010, Pages 482~489
In this paper we have proposed a new architecture of DQ-IRM(Double-Quadrature Image Rejection Mixer) for image rejection in the low-IF receiver. It consist of a frequency-tunable RF PPF(Poly Phase Filter) and the quadrature mixers. The conventional DQ-IRM generates the quadrature RF signals for the RF wide band at once. But the proposed DQ-IRM with the frequency-tuable RF PPF generates the quadrature RF signals for the narrow band of 2~3 channels bandwidth, which is partitioned from the RF wide band. We designed the CMOS RF tuner for T-DMB(Terrestrial Digital Multimedia Broadcasting) with the proposed 3rd DQ-IRM using a 0.18um CMOS technology and verified the performances of the designed receiver such as the image rejection ratio, the noise figure and the power consumption. The overall NF of the RF tuner is about 1.26 dB and the image reject ratio is about 51 dB. The power consumption is 55.8 mW at 1.8 V supply voltage. The chip area is
Sequential Spectrum Sensing Algorithm Utilizing DFT
Jung, Hoi-Yoon ; Lim, Sun-Min ; Song, Myung-Sun ;
The Journal of Korean Institute of Communications and Information Sciences, volume 35, issue 5A, 2010, Pages 490~495
In this paper, we propose an sequential spectrum sensing algorithm utilizing DFT. The conventional sensing algorithm using FFT contains redundant computation due to the characteristic of FFT which computes all frequency components at one time. The proposed sensing algorithm utilizing DFT computes a frequency component once at a time according to the priority and decides presence of signal. The proposed sensing algorithm can provide similar detection performance to the conventional scheme while computations of the sensing process could be reduced significantly depends on an early detection of signal.
Implementation of a RF transceiver for WRAN System Using Cognitive Radio Technology in TV Whitespace Band
Min, Jun-Ki ; Hwang, Sung-Ho ; Kim, Ki-Hong ; Park, Yong-Woon ;
The Journal of Korean Institute of Communications and Information Sciences, volume 35, issue 5A, 2010, Pages 496~503
The implementation of a RF transceiver for WRAN(Wireless Regional Area Network) system based on IEEE 802.22 standard using Cognitive Radio technology is presented in this paper. A CMOS RF transceiver IC for WRAN system operates in VHF/UHF(54~862MHz) broadband, and employs dual-path direct-conversion configuration and the in-band harmonic distortions are effectively suppressed by exploiting the dual-path direct conversion architecture. For 64QAM(3/4 coding rate) OFDM signal, an EVM of <-31.4dB(2.7%) has been achieved at 10dBm off-chip PA output power and the total chip area with pads is 12.95 mm2. The experimental results show that the proposed CMOS RF transceiver IC has perfect performance for WRAN system based on TDD(Time Division Duplex) mode.
Design of a 6bit 800MS/s CMOS A/D Converter Using Synchronizable Error Correction Circuit
Kim, Won ; Seon, Jong-Kug ; Yoon, Kwang-Sub ;
The Journal of Korean Institute of Communications and Information Sciences, volume 35, issue 5A, 2010, Pages 504~512
The paper proposes the 6bit 800MS/s flash A/D converter that can be applied to wireless USB chip-set. The paper simplified the error correction circuit and synchronization block as one circuit which are used respectively, and furthermore reduced the burden on the hardware. Comparing to the conventional error correction circuit, the proposed error correction circuit in this paper reduced 5 MOS transistors, the area of each error correction circuit is reduced by 9%. The A/D converter is fabricated with 0.18um CMOS 1-poly 6-metal process, and power dissipation is 182mW at 0.8Vpp input range and 1.8V supply voltage. The measured result shows 4.0bit of ENOB at 800MS/s conversion rate and 128.1MHz input frequency.
Improvement of Phase Noise Characteristics for Tuning Voltage in Voltage Controlled Oscillator using Coupled Microstrip Lines
Ryu, Keun-Kwan ; Shin, Dong-Hwan ; Yom, In-Bok ; Kim, Sung-Chan ;
The Journal of Korean Institute of Communications and Information Sciences, volume 35, issue 5A, 2010, Pages 513~518
Improvement of phase noise characteristics in a different approach of HEMT VCO (Voltage Controlled Oscillator) with coupled microstrip lines to tune the oscillating frequency is investigated. Two HEMT VCOs of 9.8GHz are manufactured in the same configuration except for the frequency tuning circuit in order to empirically demonstrate the phase noise reduction. Experimental result shows that phase noise reduction can be enhanced 8dBc/Hz at 100KHz offset frequency from carrier by frequency tuning circuit with coupled microstrip lines over the conventional VCO.
Design and Implementation of RF Module Part for Radar Detector
Roh, Hee-Chang ; Park, Wook-Ki ; Jo, Yun-Hyun ; Oh, Taeck-Keun ; Park, Hyo-Dal ;
The Journal of Korean Institute of Communications and Information Sciences, volume 35, issue 5A, 2010, Pages 519~527
In this paper, we design and implement a broadband LNA(Low Noise Amplifier), a mixer, and oscillators in RF module part for radar detector. For resolving the limitation of the conventional product that the sensitivity is low due to the poor gain flatness, we propose the architecture of RF module part. The proposed RF module part is composed with a broadband 2-stage LNA, a mixer, and three oscillators, and improves the maximum gain and gain flatness for detecting various frequencies. The overall performances of RF module part are above 38 dB conversion gain in whole band and 1 dB gain flatness. These results show that the maximum gain which is the problem of the conventional product is improved 6 dB from 35 dB to 41 dB, and gain flatness is also improved 17 dB from 22 dB to 5 dB.