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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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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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Overlay Multicast Tree Construction Algorithm for Synchronized Real-time Media Multicast Service over the Internet
Joo, Hyun-Chul ; Song, Hwang-Jun ;
The Journal of Korean Institute of Communications and Information Sciences, volume 31, issue 11A, 2006, Pages 1037~1043
This work presents an effective overlay multicast tree construction algorithm for synchronized real-time media multicast service over the Internet. The proposed algorithm is designed to minimize delay variance among group members to provide the synchronized service as well as average delay of group members in order to support the service in real-time. Basically, of orthogonal genetic algorithm is employed to obtain the near optimal tree with a low computational complexity since the given problem is NP-complete. Finally, experimental results are provided to show the superior performance of the proposed algorithm.
Compensation for the Distorted
Gbps NRZ Channels in 1,000 km NZ-DSF WDM System Using MSSI with Optimal Parameters
Lee, Seong-Real ;
The Journal of Korean Institute of Communications and Information Sciences, volume 31, issue 11A, 2006, Pages 1044~1052
In this paper the optimum position of optical phase conjugator (OPC) and the optimal dispersion coefficients of filler sections in WDM system with the conventional mid-span spectral inversion (MSSI) are numerically induced and then applied into
Gbps WDM systems with 1,000km non zero - dispersion shifted fiber(NZ-DSF) in order to efficiently compensate for the distorted overall channels. It is confirmed that the compensation extents of overall WDM channels are more improved by applying the induced optimal parameters into WDM system than those in WDM system with the conventional MSSI. So it is expected to alternate with the forming method of the symmetrical distributions of power and local dispersion by applying these optimal parameters into the real WDM system, which generate a serious problem of applying the OPC into multi-channels WDM system if it is not formed. It is also confirmed that two optimal parameters depend on each other, but less related with the finding procedure. And, it will be possible to realize the flexible system design by applying the methods proposed in this paper into the real WDM system with OPC.
Nonhermetic Plastic Packaged Optical Modules of Passive Optical Fiber Alignment Method
Lim, Dong-Cheol ; Lee, Won-Jong ; Kang, Suk-Youb ; Park, Hyo-Dal ;
The Journal of Korean Institute of Communications and Information Sciences, volume 31, issue 11A, 2006, Pages 1053~1058
In this paper, We proposed a efficient OSA(Optical Sub-Assembly) packaging method in use 1.31/1.49um bi-directional hybrid-integrated PLC chip for low-cost OSA in optical access network system applications as GE-PON in FTTH. Fabricated OSA with passive optical fiber alignment and nonhermetic plastic package method and measured optical coupling efficiency and electric-optical characteristics. Its performance is feasible to satisfy the GE-PON ONU specifications with the results as less than 0.5dB coupling losses within 40um alignment of z-axis and less than -24dBm sensitivity. It also has good temperature characteristics to sustain optical output power more than 1.5mW and 10dB extinction ratio, less than 0.3dB tracking error.
A Study on the Implement of Test Bed for Ad-hoc Networks
Lee, Heung-Jae ; Ga, Soon-Mo ; Choe, Jin-Kyun ;
The Journal of Korean Institute of Communications and Information Sciences, volume 31, issue 11A, 2006, Pages 1059~1067
AODV(Ad-hoc On-demand Distance Vector) routing protocol was devised for use of mobile nodes in Ad-hoc network. When we use the AODV routing protocol in Ad-hoc networks with high mobility, disturbance of optimized route path and link break occur. In order to solve the shortcomings, this paper proposes a new routing protocol in which new routing control messages are added to the existing AODV. The proposed protocol minimizes link break and transmission delay while is able to secure the optimized route path constantly in changes of network topology The performance of the proposed routing protocol was evaluated by using us2 network simulator. The actual Ad-hoc network test bed provides us the most reliable experimental data for Ad-hoc networks. In order to support this experimental environment, the dissertation also developed an efficient embedded system on which AODV routing protocol, NAT, Netfilter can run and other event message can be verified without declining efficiency. The correct operation of AODV routing protocol has been verified in both the Ad-hoc network test bed in which the embedded system was used, and Ad-hoc networks linked with Ethernet backbone network.
Adaptive Timing Synchronization Algorithm for WiBro Uplink
Kim, Jeong-Been ; Jin, Young-Hwan ; Kim, Kyung-Soo ; Ahn, Jae-Min ;
The Journal of Korean Institute of Communications and Information Sciences, volume 31, issue 11A, 2006, Pages 1068~1075
An adaptive ranging technique for Orthogonal Frequency Division Multiple Access(OFDMA) uplink transmission is proposed for timing synchronization of multiple mobile stations located different distances from a base station. By combining the Timing Phase Compensated Frequency Domain Cross-correlation(TPCFDC) and Frequency Domain Differential Cross-correlation(FDDC), the proposed scheme reduces the number of correlators used in ordinary TPCFDC. Repeated initial ranging attempt with the FDDC in the proposed scheme greatly reduces the hardware implementation complexity. Simulation results for ranging success probability and average ranging attempts count show that the proposed algorithm performs similarly with the ordinary TPCFDC even with the 10 times reduced complexity.
Unified Radio Resource Management for Hybrid Division Duplex System
Kim, Pil-Geun ; Kang, Chang-Gu ;
The Journal of Korean Institute of Communications and Information Sciences, volume 31, issue 11A, 2006, Pages 1076~1084
In this paper, we first review a concept of hybrid division duplexing (HDD) scheme, which has been proposed as a new type of duplexing scheme useful for a next generation mobile communication system and its implementation issues, including the unified radio resource management for HDD scheme. The HDD scheme maintains the advantages of both TDD and FDD at the same time while providing a useful structure to control the inter-cell interference, caused by an asymmetric traffic load of multimedia services over uplink and downlink in the TDD scheme. Employing two frequency bands, one for TDD scheme and the other for FDD scheme, uplink is operating under the TDD scheme only, while downlink is operating under the TDD or FDD scheme, depending on the location of mobile station. In the HDD scheme, therefore, it must determine a type of duplexing scheme to employ in the downlink and futhermore, a ratio of uplink and downlink duration to meet a given traffic load of asymmetric service, which requires some unified radio resource management for handling the subsequent inter-cell interference. In this paper, we propose a distributed adaptive control approach as a means of unified radio resource management for a HDD system that maximizes the overall system efficiency by fully utilizing the resource in TDD band, while minimizing the inter-cell interference.
Analysis of Performance and IKEv2 Authentication Exchange model in Mobile IPv6 Network
Ryu, Dong-Ju ; Kim, Gwang-Hyun ; Kim, Dong-Kook ;
The Journal of Korean Institute of Communications and Information Sciences, volume 31, issue 11A, 2006, Pages 1085~1091
For an experiment in this paper, designed test bed to secure confidentiality of data and safe transmission that Mobile node exchanges in Mobile network. And, For IPsec use that support basically in MIPv6, modeling and experimented IKEv2 protocol that is used for reliable authentication key management and distribution between End Point. When Mobile node handoff in Mobile network, analyzed effect that authentication key re-exchange and limited bandwidth that happen often get in key exchange. And studied about Performance and latency about authentication setting and exchange process that use multi interface. To conclusion, when Mobile node transmits using IPSec, re-authentication of key confirmed that re-setting by limit of bandwidth that existent Mobile network has can be impossible. According to other result, proposed MN's multi interface is expected to minimise key exchange latency by hand-off when transmit IPSec.
Performance Evaluation of Fill Rate Quasi-orthogonal STF-OFDM with DAC-ZF Decoder for Four Transmit Antennas MIMO System
Jin, Ji-Yu ; Ryu, Kwan-Woong ; Park, Yong-Wan ;
The Journal of Korean Institute of Communications and Information Sciences, volume 31, issue 11A, 2006, Pages 1092~1100
In this paper, we propose a full rate quasi-orthogonal space-time-frequency block coded orthogonal frequency division multiplexing(QOSTF-OFDM) that can achieve full symbol rate with four transmit antennas. Sincr: the proposed QOSTF-OFDM can not achieve full diversity, we use diversity advantage collection with zero forcing (DAC-ZF) decoder to compensate the diversity loss at receive side. At the same frequency efficiency, compared with linear orthogonal space-time codes which can not achieve full rate with four transmit antennas over complex constellations, low level modulation can be employed by proposed scheme due to its full rate, i.e., modulation advantage can be achieved. Due to modulation advantage and collected diversify advantage, the proposed scheme exhibits better BER performance than other orthogonal schemes.
An IPv6 based Fast Handover Deployment Scheme for WiBro Networks
Shim, Min-Sik ; Kim, Hwa-Sung ;
The Journal of Korean Institute of Communications and Information Sciences, volume 31, issue 11A, 2006, Pages 1101~1112
With the recent growth in demand for high-data rate multimedia services in the wireless environments, the Mobile Broadband Wireless Access (MBWA) technologies, such as WiBro (Wireless Broadband internet) system, are gradually coming into the spotlight. Unlike the conventional mobile communication networks based on cellular system, the WiBro system basically consists of IP based backbone networks that will be ultimately deployed by Ipv6 (IP version six) based backbone networks according to the All-IP trend for the network evolution. In such wireless mobile environments, it is needed to support the mobility management protocol on network layer as well as physical layer and Medium Access Control (MAC) layer in WiBro system. Accordingly, in this paper, we propose a fast handover scheme for improving the handover performance in IPv6 based WiBro system and show that the proposed scheme achieves loss-free and low handover latency during inter-subnet movement of the mobile stations through the simulation.
Performance Analysis of Adaptive Bandwidth and Subcarrier Allocation Scheme for a Multi-user OFDM System
Lim, Yeon-Ju ; Park, Sang-Kyu ;
The Journal of Korean Institute of Communications and Information Sciences, volume 31, issue 11A, 2006, Pages 1113~1119
For a multi-user OFDM system in mobile channels which requires low-complexity in adaptive resource allocations, resource allocation algorithm using multi-threshold is proposed. The allocation scheme, which is performed by the multi-threshold values in descending order, considers only subcarriers over each threshold level. Moreover, some subcarriers with the lowest channel gain can be· removed in the present threshold level within the constraint of satisfaction of the required data rate, in order to allocate them to the other users when the allocation process of next threshold is executed. As a result, the proposed bandwidth and subcarrier algorithm has better system performances than the conventional allocation schemes in terms of required power and processing time, which is expected as a technique that improves the spectral efficiency of OFDM systems in a mobile environment.
An Efficient Routing Algorithm for Balanced Energy Consumption in Wireless Ad-hoc Network Environments
Kim, Hyun-Ho ; Kim, Jung-Hee ; Kang, Yong-Hyeog ; Eom, Young-Ik ;
The Journal of Korean Institute of Communications and Information Sciences, volume 31, issue 11A, 2006, Pages 1120~1129
It is very important to maximize the battery durability of mobile host in wireless ad-hoc network environments, because it extends the durability and Performance of the system. Since mobile hosts play a routing role, the network structure and the location of mobile hosts create a difference of energy consumption of mobile hosts. In this paper, each mobile host maintains energy tree and evaluates the amount of the energy of the neighboring mobile hosts by using message tree packet by periods. When mobile host sets up a routing path to send a packet, it selects the most proper path in order to consume energy effectively by using energy tree and breadth first search. In this paper, we suggest that, in wireless ad-hoc network environments, if each mobile host consumes balanced energy, mobile hosts of which energy capacity is limited can work as long as it can. Therefore, the durability and performance of the system can be extended.
Improving RFID Anti-Collision Algorithms with Multi-Packet Reception
Lee, Jeong-Keun ; Kwon, Taek-Young ; Choi, Yang-Hee ; Kim, Kyung-Ah ;
The Journal of Korean Institute of Communications and Information Sciences, volume 31, issue 11A, 2006, Pages 1130~1137
One of the important performance issues in large-scale RFID systems is to resolve collisions among responses from RFID tags. Considering two do facto anti-collision solutions, namely the binary-tree splitting algorithm and the Slotted-Aloha algorithm, we propose to use multi-packet reception (MPR) capability to enhance the RFID tag reading rate (i.e., throughput). MPR allows an RFID reader to receive multiple reponses transmitted by tags at the same time. We analyze the effect of MPR capability in the above anti-collision algorithms, which is also validated by simulation. The analysis and simulation results show that RFID reader antenna design and signal separation techniques play an important role in improving RFID system performance with MPR capability.
Improved Sensor MAC Protocol for Wireless Sensor Network
Lee, Ju-a ; Kim, Jae-Hyun ; Min, Seung-Wook ;
The Journal of Korean Institute of Communications and Information Sciences, volume 31, issue 11A, 2006, Pages 1138~1146
It is very important for the sensor network to save battery capacity. Switching active mode to sleep mode is used for S-MAC protocol and expiring timer before end of the active part is used for T-MAC in order to extend battery life span. We proposed IS-MAC (Improved Sensor MAC) which gives more energy efficiency than S-MAC and T-MAC To improve energy efficiency in sensor network, we used the threshold value in buffer to transmit data packet and proposed the method to reduce the number of control packets which cause extra battery consumption. Based on the analytical results, we found that the proposed IS-MAC protocol shows better performance than conventional MAC protocols.
Neighbor Node Discovery and Load Balancing Schemes for Energy-Efficient Clustering in Wireless Sensor Networks
Choi, Ji-Young ; Kang, Chung-Gu ;
The Journal of Korean Institute of Communications and Information Sciences, volume 31, issue 11A, 2006, Pages 1147~1158
Clustering algorithm is an essential element to implement a hierarchical routing protocol, especially for a large-scale wireless sensor network. In this paper, we propose a new type of energy-efficient clustering algorithm, which maximizes the physical distance between cluster head and gateway by a neighbor node discovery mechanism. Furthermore, a slave/master patching scheme is introduced as a useful means of further improving the energy-efficiency. It has been shown that the number of cluster heads can be reduced by as many as 21% as compared with the existing clustering algorithms.
Performance Improvement in Passive Tag Based RFID Reader
Rhee, Seung-Hak ; Chun, Jong-Hun ; Park, Jong-An ;
The Journal of Korean Institute of Communications and Information Sciences, volume 31, issue 11A, 2006, Pages 1159~1166
In this paper, we have designed a RFID reader receiver system for improving the performance of the passive Tag based 9
RFID reader, and analyzed the system performance according to the frequency, the reader, and tag properties. The commercial receive system causes a loss in sensitivity because of 24 capacitors and 6 inductors. So we have designed an improved system using a circulator, LNA and a SAW filter. The experimental results show that the use of a circulator to separate the Tx/Rx paths eliminates interference, the LNA improves the sensitivity of the Rx module and SAW filter eliminates the noise and spurious components in the received signal.
An FPGA Implementation of an MML-DFE for Spatially Multiplexed MIMO Systems
Im, Tae-Ho ; Lee, Kyu-In ; Park, Chang-Hwan ; Jeong, Ki-Cheol ; Yu, Sung-Wook ; Kim, Jae-Kwon ; Cho, Yong-Soo ;
The Journal of Korean Institute of Communications and Information Sciences, volume 31, issue 11A, 2006, Pages 1167~1175
The ML-DFE(Maximum Likelihood-Decision Feedback Equalization) can be viewed as either a suboptimal signal detection method for reducing hardware complexity of ML or an enhanced detection method for reducing the effect of error propagation of SIC(Successive Interference Cancellation) in spatially multiplexed MIMO systems such as V-BLAST. The ML-DFE can achieve a higher diversity in rich scattering environments as well as reducing the error propagation effect by combing ML decoding with the DFE. In this paper, an MML-DFE(Modified Maximum Likelihood-Decision Feedback Equalization) is proposed to reduce the hardware complexity of the ML-DFE, without compromising performance. It is shown by FPGA implementation that the proposed MML-DFE can achieve the same performance as the ML-DFE with significantly reduced hardware complexity.