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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 32, Issue 12C - Dec 2007
Volume 32, Issue 12B - Dec 2007
Volume 32, Issue 12A - Dec 2007
Volume 32, Issue 11C - Nov 2007
Volume 32, Issue 11B - Nov 2007
Volume 32, Issue 11A - Nov 2007
Volume 32, Issue 10C - Oct 2007
Volume 32, Issue 10B - Oct 2007
Volume 32, Issue 10A - Oct 2007
Volume 32, Issue 9C - Sep 2007
Volume 32, Issue 9B - Sep 2007
Volume 32, Issue 9A - Sep 2007
Volume 32, Issue 8C - Aug 2007
Volume 32, Issue 8B - Aug 2007
Volume 32, Issue 8A - Aug 2007
Volume 32, Issue 7C - Jul 2007
Volume 32, Issue 7B - Jul 2007
Volume 32, Issue 7A - Jul 2007
Volume 32, Issue 6C - Jun 2007
Volume 32, Issue 6B - Jun 2007
Volume 32, Issue 6A - Jun 2007
Volume 32, Issue 5C - May 2007
Volume 32, Issue 5B - May 2007
Volume 32, Issue 5A - May 2007
Volume 32, Issue 4C - Apr 2007
Volume 32, Issue 4B - Apr 2007
Volume 32, Issue 4A - Apr 2007
Volume 32, Issue 3C - Mar 2007
Volume 32, Issue 3B - Mar 2007
Volume 32, Issue 3A - Mar 2007
Volume 32, Issue 2C - Feb 2007
Volume 32, Issue 2B - Feb 2007
Volume 32, Issue 2A - Feb 2007
Volume 32, Issue 1C - Jan 2007
Volume 32, Issue 1B - Jan 2007
Volume 32, Issue 1A - Jan 2007
Selecting the target year
Goal-Pareto based NSGA-II Algorithm for Multiobjective Optimization
Park, Soon-Kyu ; Lee, Su-Bok ; Lee, Won-Cheol ;
The Journal of Korean Institute of Communications and Information Sciences, volume 32, issue 11A, 2007, Pages 1079~1085
This Paper Proposes a new optimization algorithm named by GBNSGA-II(Goal-pareto Based Non-dominated Sorting Genetic Algorithm-II) which uses Goal Programming to find non-dominated solutions in NSGA-II. Although the conventional NSGA is very popular to solve multiobjective optimization problem, its high computational complexity, lack of elitism and difficulty of selecting sharing parameter have been considered as problems to be overcome. To overcome these problems, NSGA-II has been introduced as the alternative for multiobjective optimization algorithm preventing aforementioned defects arising in the conventional NSGA. Together with advantageous features of NSGA-II, this paper proposes rather effective optimization algorithm formulated by purposely combining NSGA-II algorithm with GP (Goal Programming) subject to satisfying multiple objectives as possible as it can. By conducting computer simulations, the superiority of the proposed GBNSGA-II algorithm will be verified in the aspects of the effectiveness on optimization process in presence of a priori constrained goals and its fast converging capability.
Non-coherent TOA Estimation Method based on IR-UWB in Multiple SOP Environments
Park, Woon-Yong ; Park, Cheol-Ung ; Choi, Sung-Soo ; Lee, Won-Cheol ;
The Journal of Korean Institute of Communications and Information Sciences, volume 32, issue 11A, 2007, Pages 1086~1095
This paper proposes a novel non-coherent TOA estimation scheme using multiple correlation process on the existence of multiple simultaneously operating piconets (SOPs). Impulse radio-ultra wideband (IR-UWB) based on direct sequence spread spectrum (DSSS) using Gold sequence is employed in order to discriminate each piconet. In order to enhance the characteristic of correlation, this paper presents the method of multiple mask operation (MMO). The time of arrival (TOA) of direct line of sight (DLOS) path is estimated via two step coarse/fine timing detection. To verify the performance of proposed scheme, two distinct channel models approved by IEEE 802.15.4a Task Group (TG) are considered. According to the simulation results, it could conclude that the proposed scheme have performed better performance than the conventional method well even in densed indoor multi-path environment as well as in the existence of multiple SOPs.
Cognitive Radio Using ITMA for MB-OFDM UWB System of Korea
Kim, Tae-Hun ; Kim, Dong-Hee ; Jang, Hong-Mo ; Nam, Sang-Kyun ; Kwak, Kyung-Sup ;
The Journal of Korean Institute of Communications and Information Sciences, volume 32, issue 11A, 2007, Pages 1096~1105
In this paper, we propose a solution on interference problem of MB-OFDM UWB system using cognitive radio. We use interference temperature model of cognitive radio that has proposed by FCC for estimating interference signal. Calculating channel capacity of MB-OFDM UWB system with interference temperature, we suggest how to solve interference problem. We have used genetic algorithm in cognitive engine's calculation process. The proposed MB-OFDM UWB System with cognitive radio shows very efficient in solving interference problem.
Hybrid Scheduling Algorithm for Guaranteeing QoS of Real-time Traffic in WCDMA Enhanced Uplink
Kang, You-Jin ; Kim, Jun-Su ; Sung, Dan-Keun ;
The Journal of Korean Institute of Communications and Information Sciences, volume 32, issue 11A, 2007, Pages 1106~1112
As a demand for high speed uplink packet services increases, the WCDMA enhanced uplink, also known as high speed uplink packet access (HSUPA), has been specified in release 6 by 3GPP. This HSUPA will provide various types of multimedia services, such as real-time video streaming, gaming, VoIP, and FTP. Generally, the performance of HSUPA is dominated by scheduling policy. Therefore, it is required to design a scheduling algorithm considering the traffic characteristics to provide QoS guaranteed services in various traffic environments. In this paper, we propose a scheduling algorithm considering the traffic characteristics to guarantee QoS in a mixed traffic environment. Finally, the performance of the proposed scheduling algorithm is evaluated in terms of average packet delay, packet delay jitter, and system throughput using a system level simulator.
Performance Comparisons on the Strategies of Sleep Window Size Adjustment for Power Saving in IEEE 802.16e
Son, Dae-Hong ; Roh, Byeong-Hee ;
The Journal of Korean Institute of Communications and Information Sciences, volume 32, issue 11A, 2007, Pages 1113~1119
In this paper, first, we proposed various possible candidate schemes for determining initial sleep window size and varying sleep window size in sleep mode for power saving class I of IEEE 802.16e. Then, we analyzed and compared the power saving performances of those schemes. The schemes used for the comparisons are EICV of IEEE 802.16e, and other comparable schemes such as EIED, EILD, LIED and LILD. Experimental results show that LILD and EIED outperform other comparable schemes. Especially, EIED shows the better performances for the case of high traffic intensity environments, while LILD does for the low traffic intensity case.
A Dynamic Resource Allocation scheme with a GPS algorithm in Cellular-based Hybrid and Distributed Wireless Multi-hop Systems
Bae, Byung-Joo ; Kim, Dong-Kun ; Shin, Bong-Jhin ; Kang, Byoung-Ik ; Hong, Dae-Hyoung ; Choe, Jin-Woo ;
The Journal of Korean Institute of Communications and Information Sciences, volume 32, issue 11A, 2007, Pages 1120~1127
In this paper, we propose a generalized processor sharing - dynamic resource allocation (GPS-DRA) scheme which allocates the required amount of resources to each hop dynamically in cellular-based multi-hop systems. In the hybrid-distributed system considered in this paper, a central controller such as a base station (BS) should allocate resources properly to each hop. However, due to changing channel condition with time, it is difficult to allocate as much amount of resources as each hop needs for transmission. GPS-DRA scheme allocates the required amount of resources dynamically to each hop based on the amount of resources used in previous frames by each hop. The amount of control overhead generated by GPS-DRA scheme can be very small because a central controller doesn't need to collect all link information for resource allocation. Our simulation results show that channel utilization increased about 16% and cell capacity increased about 65% compared to those of fixed resource allocation (FRA) scheme.
A Study on the Fingerprint-based User Authentication Protocol Considering both the Mobility and Security in the Telematics Environment
Kim, Tae-Sub ; Oh, Ryong ; Lee, Sang-Joon ; Lee, Sung-Ju ; Kim, Hak-Jae ; Chung, Yong-Wha ; Cho, Choong-Ho ;
The Journal of Korean Institute of Communications and Information Sciences, volume 32, issue 11A, 2007, Pages 1128~1137
Recently, according to being advanced internet, mobile communication technique, Telematics environment which users in vehicle can use internet service in LAN(Local Area Network) via mobile device has being realized. In this paper, we propose the remote user authentication protocol to solve these issues. Additionally, we use biometrics(fingerprint) for our user authentication protocol cause it can provide to avoid critical weakness that can be lost, stolen, or forgotten and to make authentication easily. In our user authentication protocol, to protect the biometric we use session key which is generated from master key distributed in our key distribution protocol. In particular, we propose secure protocol between APs considering weakness of security in mobile environment. Based on implementation of our proposed protocol, we conform that our proposed protocols are secure from various attack methods and provide real-time authentication.
Performance of DCSK under the Coexistence of non-Chaotic Transmit Reference System
Thapaliya, Karuna ; Kwak, Kyung-Sup ;
The Journal of Korean Institute of Communications and Information Sciences, volume 32, issue 11A, 2007, Pages 1138~1145
In wireless communications, chaotic communications have been a field of interest due to its low complexity in hardware implementation and low power consumption in chaotic signal generation. Among the modulation schemes using the chaotic signal, Differential Chaos Shift Keying (DCSK) is a robust non coherent technique. As in the conventional communication systems, chaos-based systems are required to provide reasonable bit error performance in the presence of a narrow-band signal coming from any other systems. The frequency band of this foreign narrow band signal may lie within the bandwidth of the chaos-based systems. This situation may occur when chaotic signal transmission is done in the presence of other conventional communication system. This paper has evaluated the performance of the non coherent differential chaos shift keying (DCSK) system under the presence of conventional non-chaotic transmit reference system. Both systems are assumed to have same data rates. The mathematical expressions for the bit error rate (BER) are derived with computer simulations to verify the analytical results.
Novel allocation method of tiles in Subchannel for I/Q imbalances Estimation in WiBro uplink
Kim, Hye-Jin ; Jin, Young-Hwan ; Ahn, Jae-Min ;
The Journal of Korean Institute of Communications and Information Sciences, volume 32, issue 11A, 2007, Pages 1146~1153
In this paper, we analyze the I/Q imbalances effects at the WiBro uplimk when using direct-conversion RF transceiver. If I/Q imbalance exists, the transmit signal is spread over two sbcarriers. As a result, phenomenon of performance reducing is produced. Contrary to OFDM system in which one user uses all subcarrier, symmetrical two subcarriers are assigned other users in OFDMA system. I/Q imbalances elements can't be estimated such a conventional allocation method of tiles in subchannel and compensated. In order to solve the problem, We propose a new method in order that symmetrical two subcarriers are assigned one user. If novel method is applied, we can estimate I/Q imbalances and compensate distortion received signal. As a result, we can obtain a performance similar performance when I/Q imbalances is not existed. Also, if proper detection methods are used, we get the effect of performance improvement, because of diversity gain what is happened due to combining I/Q imbalances with multi path fading channel.
Residual ISI cancellation and EM-based channel estimation for STBC/SFBC OFDM with insufficient cyclic prefix
Won, Hui-Chul ;
The Journal of Korean Institute of Communications and Information Sciences, volume 32, issue 11A, 2007, Pages 1154~1163
For orthogonal frequency division multiplexing (OFDM), cyclic prefix (CP) should be longer than the length of channel impulse response. In order to prevent a loss of bandwidth efficiency due to the use of a CP, residual intersymbol interference cancellation (RISIC) method has recently been developed. In this paper, we first apply the RISIC algorithm to the space-time block coded (STBC) OFDM and the space-frequency block coded (SFBC) OFDM with insufficient CP. It is shown that in the STBC OFDM, tail cancellation as well as cyclic restoration of the RISIC should be repeated. Second, we propose iterative channel estimation method for the RISIC in the STBC OFDM system with insufficient CP. Based on the expectation-maximization (EM) algorithm, the proposed estimation method exploits the extrinsic probabilities of the channel decoder iteratively. The performance of the proposed method is evaluated by computer simulation in a multipath fading environment.
Cluster Label-based ZigBee Mesh Routing Protocol
Lee, Kwang-Koog ; Kim, Seong-Hoon ; Park, Hong-Seong ;
The Journal of Korean Institute of Communications and Information Sciences, volume 32, issue 11A, 2007, Pages 1164~1172
To solve scalability problem in the ZigBee Network, this paper presents a new mesh routing protocol for ZigBee, called ZigBee Cluster Label (ZiCL). ZiCL divides the ZigBee network into one or more logical clusters and then assigns a unique Cluster Label to each cluster so that it discovers a route of a destination node based on Cluster Label. When a node collects new Cluster Label information of a destination node according to discovery based on Cluster Label, ZiCL encourages nodes with the same Cluster Label to share the information. Consequen tly, it contributes on reducing numerical potential route discoveries and improving network performances such as routing overhead, end-to-end delay, and packet delivery ratio. Simulation results using NS-2 show ZiCL performs well.
Local Repair Routing Algorithm using Link Breakage Prediction in Mobile Ad Hoc Networks
Yoo, Dae-Hun ; Choi, Woong-Chul ;
The Journal of Korean Institute of Communications and Information Sciences, volume 32, issue 11A, 2007, Pages 1173~1181
A number of routing algorithms have been studied for wireless mobile ad-hoc network. Among them, the AODV routing algorithm with on-demand method periodically transmits hello message and monitors link state during data transmission in order to maintain routing paths. When a path is disconnected, a node that senses it transmits a RERR packet to the transmitting node or transmits a RREQ locally so that the path could be repaired. With that, the control packet such as a RREQ is broadcast, which causes the consumption of bandwidth and incurs data latency. This paper proposes a LRRLBP algorithm that locally repairs a path by predicting link state before disconnecting the path based on the AODV routing protocol for solving such problems. Intensive simulations with the results using NS-2 simulator are shown for verifying the proposed protocol.
An On/Off Power Control for OFDM Transmission Scheme in a Cochannel Interference Environment
Park, Jin-Kyu ; Lim, Chang-Heon ; Kim, Jin-Yul ;
The Journal of Korean Institute of Communications and Information Sciences, volume 32, issue 11A, 2007, Pages 1182~1189
Frequency reuse in a cellular wireless communication environment gives rise to a phenomenon of cochannel interference. This paper introduces a power control strategy for OFDM based communication systems operating in such an environment. Among the existing power control schemes, IWF(iterative waterfilling) is known to exhibit relatively good performance. However, it requires feedback of power level and bit allocation information for each subcarrier from a receiver to its associated transmitter, which can lead to a considerable overhead, especially for the case of employing large number of subcarriers. Motivated by this, we present a simplified power control scheme with reduced overhead feedback, which allocates some nonzero identical power to the subcarriers of which channel conditions are above a certain threshold and zero power to the other ones. Computer simulations show that the proposed strategy produces a good approximation to the performance of the IWF in terms of the transmission power level while it requires less overhead feedback.
A Study of Vein Identification System using 2D-Gabor Filter for the Vessel USN Entrance/Exit Management
Choi, Myeong-Soo ; Lee, Seong-Ro ; Sin, Sang-Woo ; Jang, Kyung-Sik ; Jung, Min-A ;
The Journal of Korean Institute of Communications and Information Sciences, volume 32, issue 11A, 2007, Pages 1190~1196
In this paper, we propose the biometrics system using hand vein pattern. This system is for management about person's entrance/exit in vessel USN. we select the biometrics method using hand vein pattern as adoptable method to vessel USN environment. Our experimental results show that preprocessing using two dimensional gabor filter achieves performance improvements over high pass filtering. Also, we compared our method with measured FAR(False Acceptance Rate) and FRR(False Rejection Rate) using pattern matching, the results show low error rate over high pass filtering. As a result, we verify the adoptability of biometrics system using hand vein pattern in management of person's entrance/exit in vessel.
An Adaptive K-best Algorithm Based on Path Metric Comparison for MIMO Systems
Kim, Bong-Seok ; Choi, Kwon-Hue ;
The Journal of Korean Institute of Communications and Information Sciences, volume 32, issue 11A, 2007, Pages 1197~1205
An adaptive K-best detection scheme is proposed for MIMO systems. The proposed scheme changes the number of survivor paths, K based on the degree of the reliability of Zero-Forcing (ZF) estimates at each K-best step. The critical drawback of the fixed K-best detection is that the correct path's metric may be temporarily larger than K minimum paths metrics due to imperfect interference cancellation by the incorrect ZF estimates. Based on the observation that there are insignificant differences among path metrics (ML distances) when the ZF estimates are incorrect, we use the ratio of the minimum ML distance to the second minimum as a reliability indicator for the ZF estimates. So, we adaptively select the value of K according to the ML distance ratio. It is shown that the proposed scheme achieves the significant improvement over the conventional fixed K-best scheme. The proposed scheme effectively achieves the performance of large K-best system while maintaining the overall average computation complexity much smaller than that of large K system.
Flight Measurement and Analysis for Signal Influence of CVOR and DVOR by It's Surrounding Obstacle Condition
Park, Hyeong-Taek ; Hwang, Byong-Won ;
The Journal of Korean Institute of Communications and Information Sciences, volume 32, issue 11A, 2007, Pages 1206~1212
International Civil Aviation Organization(ICAO) adopted VOR(Very high frequency Omni-Range) as an international standard air navigation system in 1949 and recommended every country to make use of it in formulating air route and guiding take-off and landing of an aircraft. VOR is quite a useful navigation system so that more than 2,000 VORs are currently installed all over the world including 39 in the Republic of Korea; however, VOR signal could be easily affected by its circumstance like a mountainous area because it provides navigation information to an aircraft through AM and FM of VHF carrier. There are two types of VOR which are defined according to a design methode. Therefore this study intends to investigate which type of VOR is suitable for mountainous area. For that purpose, the performance of each CVOR and DVOR is measured and analyzed by using an aircraft equipped with measuring instruments. The analyzed result will be applied and utilized in selecting the VOR type, so it could be a feasible solution of problem related to the VOR relocation due to its insufficient performance in the future.
Actual Conditions of Spill Over by the Japan TV Broadcasting Signals
Hue, Young-Tae ; Kim, Hyun ; Woo, Jong-Woo ;
The Journal of Korean Institute of Communications and Information Sciences, volume 32, issue 11A, 2007, Pages 1213~1218
In this study, we have been constructed measuring system for spill over by the Japan TV broadcasting signals and analyzed those signals using APD curve. In Busan, we have been measured channel of Japan TV broadcasting signals during 9 months. The quality of image is that maximum grade is 2.5 level, and the quality of sound is that maximum grade is 3 level. In the result of analysis for measured Japan TV broadcasting signals, we have been observed Japan TV broadcasting signals those we have been chosen the ch 36 and ch 38, plotted the APD curve of each channel for a season, in Specially.