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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 31, Issue 12C - Dec 2006
Volume 31, Issue 12B - Dec 2006
Volume 31, Issue 12A - Dec 2006
Volume 31, Issue 11C - Nov 2006
Volume 31, Issue 11B - Nov 2006
Volume 31, Issue 11A - Nov 2006
Volume 31, Issue 10C - Oct 2006
Volume 31, Issue 10B - Oct 2006
Volume 31, Issue 10A - Oct 2006
Volume 31, Issue 9C - Sep 2006
Volume 31, Issue 9B - Sep 2006
Volume 31, Issue 9A - Sep 2006
Volume 31, Issue 8C - Aug 2006
Volume 31, Issue 8B - Aug 2006
Volume 31, Issue 8A - Aug 2006
Volume 31, Issue 7C - Jul 2006
Volume 31, Issue 7B - Jul 2006
Volume 31, Issue 7A - Jul 2006
Volume 31, Issue 6C - Jun 2006
Volume 31, Issue 6B - Jun 2006
Volume 31, Issue 6A - Jun 2006
Volume 31, Issue 5C - May 2006
Volume 31, Issue 5B - May 2006
Volume 31, Issue 5A - May 2006
Volume 31, Issue 4C - Apr 2006
Volume 31, Issue 4B - Apr 2006
Volume 31, Issue 4A - Apr 2006
Volume 31, Issue 3C - Mar 2006
Volume 31, Issue 3B - Mar 2006
Volume 31, Issue 3A - Mar 2006
Volume 31, Issue 2C - Feb 2006
Volume 31, Issue 2B - Feb 2006
Volume 31, Issue 2A - Feb 2006
Volume 31, Issue 1C - Jan 2006
Volume 31, Issue 1B - Jan 2006
Volume 31, Issue 1A - Jan 2006
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Pump Light Porer of Wideband Optical Phase Conjugator Dependence on Amplifier Spacing in 320 Gbps WDM Systems with MSSI
Lee Seong-Real ;
The Journal of Korean Institute of Communications and Information Sciences, volume 31, issue 8A, 2006, Pages 735~744
In this paper, the optimum pump light powers of optical phase conjugator(OPC) are numerically investigated as a function of amplifier spacing in 1,200 km
Gbps WDM systems with 0.1, 0.4, 0.8, or 1.6 ps/nm/km dispersion coefficient. It is confirmed that the variation of optimal pump light power dependence on amplifier spacing for NRZ transmission system is smaller than that for RZ transmission system through the evaluations and analysis of eye opening penalty(EOP) characteristics. And, in both cases of NRZ and RZ transmission, the variation of optimal pump light power is more increased as amplifier spacing becomes longer. Additionally, it is confirmed that the best amplifier spacing in NRZ and RZ transmission system is 50 km.
A Novel Two-step Channel Prediction Technique for Adaptive Transmission in OFDM/FDD System
Heo Joo ; Chang Kyung-Hi ;
The Journal of Korean Institute of Communications and Information Sciences, volume 31, issue 8A, 2006, Pages 745~751
The transmitter requires knowledge of the channel status information in order to adopt the adaptive modulation and coding scheme(AMC) for OFDM system. But in the outdoor environment which the users have high mobility, the channel status information from the users is outdated, so that it induces the degradation of system throughput and packet error rate(PER) performance. To solve this problem, researches about applying channel prediction technique to the AMC scheme have been proceeded. Most channel prediction techniques assume that there is no channel variation in the predefined time duration, e.g., a slot. As a result, those techniques cannot compensate the degradation of PER performance resulting from the rapid variation of channel during the slot duration. This paper introduces a novel channel prediction technique for OFDM/FDD system to support adaptive modulation and coding scheme over rapidly time-varying multipath fading channel. The proposed channel prediction technique considers the time-varying nature of channel during the slot duration. Simulation results show that the AMC scheme of OFDM/FDD system utilizing the proposed channel prediction technique can guarantee the target PER of 1% without any loss of system throughput compared with the case supported by the conventional channel prediction under ITU-R Veh A 30km/h.
A Comparative Performance Analysis of High Resolution Direction Finding Algorithms in Wideband Mobile Environments
Yun Young-Ho ; Park Yoon-Ok ; Park Hyung-Rae ;
The Journal of Korean Institute of Communications and Information Sciences, volume 31, issue 8A, 2006, Pages 752~759
In this paper, the performances of representative high resolution direction finding algorithms are evaluated and compared in wideband mobile environments. The angular spread phenomenon in mobile environments is first investigated and then a vector channel model for wideband OFDMA signals is derived. A direction finding system architecture for OFDMA smart antenna systems is proposed and finally the performances of high resolution direction finding algorithms are evaluated in wideband mobile environments by taking the WiBro system as a target system.
An Efficient frame size Decision and Resource Allocation Method for Multiuser OFDM/TDD System in Multicell Environment
Keum Seung-Won ; Kim Jung-Gon ; Shin Kil-Ho ; Kim Hyung-Myung ;
The Journal of Korean Institute of Communications and Information Sciences, volume 31, issue 8A, 2006, Pages 760~768
In this paper, an novel resource allocation scheme is proposed for adaptive multiuser OFDM-TDD systems in multiuser, multicell and frequency-selective time-varying channels. The optimal frame size and mode switching level of each user is determined by maximizing the spectrum efficiency. In multi-cell environment, the allocation scheme must consider the cochannel interference of other cells. The measured SINR is changed in one frame size because the interference is changed. The frame size is determined to consider both the optimal frame size and cochannel user's frame size of other cells. we propose the efficient resource allocation scheme which is satisfied the target BER.
Power-limited Cooperative Diversity with Selection Combining in Rayleigh Fading for Wireless Ad-hoc Networks
Kim Nam-Soo ; Lee Ye-Hoon ;
The Journal of Korean Institute of Communications and Information Sciences, volume 31, issue 8A, 2006, Pages 769~774
Based on the performance of a cooperative diversity with selection combining in Rayleigh fading, the power control range of a relay node is investigated. Also the effect of the power-limited relay node to the system performance is investigated. If the average signal-to-noise ratio(SNR) of each signal path is equal, the single relay cooperative diversity is obtained 13.5dB gain at the outage probability of
in Rayleigh fading. We noticed that the limited power of a relay node severely degrades the system performance. Therefore the node with limited power in ad-hoc network is not recommended as a relay node in cooperative diversity system.
English Performance of MIMO-OFDM Combing Bemaformer with Space-time Decoder in Multiuser Environments
Kim Chan-Kyu ;
The Journal of Korean Institute of Communications and Information Sciences, volume 31, issue 8A, 2006, Pages 775~783
In this paper, the new technique combining beamforming with space-time coding is proposed for an orthogonal frequency division multiplexing(OFDM) system with multi-input multi-output(MIMO). When MIMO-OFDM system is employing Nt(the number of transmitterantenna) beamfomers and one S-T decoder at Nr receiver antennas, Nt signals removed CCI are outputted at the beamformer and then diversity gain can be got through space-time decoding. As the proposed technique can reduce cochannel interference and get diversity gain in the multi-user environment, the performance of MIMO-OFDM system is very improved. BER performance improvement and convergence behavior of the proposed approach are investigated through computer simulation by applying it to MIMO-OFDM system in the multi-user environment.
Bitwise Decomposition Algorithm for Gray Coded M-PSK Signals
Kim Ki-Seol ; Hyun Kwang-Min ; Park Sang-Kyu ;
The Journal of Korean Institute of Communications and Information Sciences, volume 31, issue 8A, 2006, Pages 784~789
In this paper, we propose a bitwise information decomposition algorithm for an M-PSK signal based on the Max-Log-MAP algorithm. In order to obtain the algorithm, we use a coordinate transformation from M-PSK to M-PAM signal space. Using the proposed algorithm, we analyze the performance of a Turbo iterative decoding method. The proposed algorithm can be applicable not only for a communication with PSK and iterative decoding method but for adaptive modulation and coding system.
A Performance Analysis of Power Saving Modes on IEEE 802.16e Mobile Terminal
Park Jae-Sung ; Kim Beom-Joon ;
The Journal of Korean Institute of Communications and Information Sciences, volume 31, issue 8A, 2006, Pages 790~797
IEEE 802.16e specifies two different power saving modes(PSM). One is sleep mode and the other is idle mode. These modes are different in that whether a mobile node maintains its state information with the serving base station or not. This difference results in different efficiency in consuming battery power of a mobile terminal. Therefore, it becomes important to analyze the performance of each power saving mode considering the parameters affecting the power consumption. In this paper, we propose a performance modeling framework of sleep mode and idle mode in terms of power saving efficiency. The analytical results are verified by computer simulations that idle mode is superior to sleep mode in power consumption of mobile node.
Feedback Reduction of Channel Quality Information for Multiuser MIMO Systems
Cho Myeon-Gyun ; Kim Young-Ju ; Hong Dae-Sik ;
The Journal of Korean Institute of Communications and Information Sciences, volume 31, issue 8A, 2006, Pages 798~803
An opportunistic scheduling is adopted to improve the capacity of the system by exploiting the multiuser diversity of multiuser MIMO(MU-MIMO) systems. However it requires the large amount of feedback carrying the channel quality information(CQI) of each user to the transmitter, The considered per user unitary and rate control(PU2RC) needs to feedback the preferred preceding index and its CQIs, and it has a defect in scheduling the streams for the grouped user. In order to overcome these drawbacks, a novel feedback reduction scheme is proposed in this paper. It employs transmitter controlled preceding and opportunistic feedback(TCP-OFB). The simulation results demonstrate that TCP-OFB shows comparable performance to PU2RC while it only requires far reduced feedback load.
Wireless PKI Based Certificate Verification Using Virtual Identifier
Choi Seung-Kwon ; Shin Jung-Won ; Shin Dong-Hwa ; Kim Sun-Chul ; Lee Byong-Rok ; Cho Young-Hwan ;
The Journal of Korean Institute of Communications and Information Sciences, volume 31, issue 8A, 2006, Pages 804~813
In wireless Internet environment that demand of wireless Internet service increase steadily, wireless PKI(Public Key Infrastructure) service is appearing on stage as necessary essential base technology for information protection service offer, In this paper, we propose the method for verification to reduce the communication overload using VID to CSMP made with a goal of the performance guarantee for security and use in a real time and examine the existent certificate verification methods. The performance of security and the use in a real time is guaranteed by managing the note of authentification by the person who verifies and reducing the amount of the data transmission using VID.
Analysis of Interference Impact of UWB System on WiBro System
Yoon Young-Keun ; Hong Heon-Jin ; Lee Il-Kyoo ; Choi Ik-Guen ; Kwak Kyung-Sub ;
The Journal of Korean Institute of Communications and Information Sciences, volume 31, issue 8A, 2006, Pages 814~819
This paper presents the impacts of Ultra Wide-Band(UWB) system applied in Indoor and Handhold communications using frequency band from 3.1 GHz to 10.6 GHz on Wireless Broad-band(WiBro) system based on Orthogonal Frequency Division Multiplexing(OFDM) using frequency of 2.3 GHz. The Minimum Coupling Loss(MCL) method for the case of single interference and Monte Carlo(MC) simulation for multiple interference considering practical scenario were used to evaluate the interference effects of UWB system on WiBro system. As a result, the minimum separation distance between single interferer and the victim receiver required 34.4 m and above to guarantee the co-existence. Also, the UWB transmitting PSD of around - 81 dBm / MHz below should be required to meet the minimum throughput loss of WiBro mobile station in case of multiple UWB interference.
A Study on Automatic Interface Generation by Protocol Mapping
Lee Ser-Hoon ; Kang Kyung-Goo ; Hwang Sun-Young ;
The Journal of Korean Institute of Communications and Information Sciences, volume 31, issue 8A, 2006, Pages 820~829
IP-based design methodology has been popularly employed for SoC design to reduce design complexity and to cope with time-to-market pressure. Due to the request for high performance of current mobile systems, embedded SoC design needs a multi-processor to manage problems of high complexity and the data processing such as multimedia, DMB and image processing in real time. Interface module for communication between system buses and processors are required, since many IPs employ different protocols. High performance processors require interface module to minimize the latency of data transmission during read-write operation and to enhance the performance of a top level system. This paper proposes an automatic interface generation system based on FSM generated from the common protocol description sequence of a bus and an IP. The proposed interface does not use a buffer which stores data temporally causing the data transmission latency. Experimental results show that the area of the interface circuits generated by the proposed system is reduced by 48.5% on the average, when comparing to buffer-based interface circuits. Data transmission latency is reduced by 59.1% for single data transfer and by 13.3% for burst mode data transfer. By using the proposed system, it becomes possible to generate a high performance interface circuit automatically.
Performance Improvement of AODV Routing Algorithm Using Timestamp
Lee Jae-Suk ; Park Hae-Ryeon ; Lee Kee-Hyun ; Suk Jung-Bong ;
The Journal of Korean Institute of Communications and Information Sciences, volume 31, issue 8A, 2006, Pages 830~836
One of the seminal operation parameters of AODV is the node-to-node travel time of data, which is currently set to fixed value of 40 ms in the RFC3561 and widely used to compute other parameters such as the expected round-trip time of the connection setup message, etc. We have naturally thought the network performance could be improved by dynamically varying the node-to-node travel time with respect to the traffic condition in the networt rather than using the fixed value, which motivates this work. To this end, we apply the idea of using timestamp; every node places the current time in the message before sending it out, and the receiver node computes the node travel time based on the moving average algorithm by considering not only the current value but also the previous ones in an accumulated and exponentially decreasing fashion with time. We evaluate the performance of the proposed scheme in respect of the number of RREQ messages generated, throughput, and delay as a function of traffic load and node mobility, and compare the result with the original AODV scheme. The results show that the proposed scheme presents noticeable performance improvements, expecially under the condition of high node mobility and high traffic load.