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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 33, Issue 12C - Dec 2008
Volume 33, Issue 12B - Dec 2008
Volume 33, Issue 12A - Dec 2008
Volume 33, Issue 11C - Nov 2008
Volume 33, Issue 11B - Nov 2008
Volume 33, Issue 11A - Nov 2008
Volume 33, Issue 10C - Oct 2008
Volume 33, Issue 10B - Oct 2008
Volume 33, Issue 10A - Oct 2008
Volume 33, Issue 9C - Sep 2008
Volume 33, Issue 9B - Sep 2008
Volume 33, Issue 9A - Sep 2008
Volume 33, Issue 8C - Aug 2008
Volume 33, Issue 8B - Aug 2008
Volume 33, Issue 8A - Aug 2008
Volume 33, Issue 7C - Jul 2008
Volume 33, Issue 7B - Jul 2008
Volume 33, Issue 7A - Jul 2008
Volume 33, Issue 6C - Jun 2008
Volume 33, Issue 6B - Jun 2008
Volume 33, Issue 6A - Jun 2008
Volume 33, Issue 5C - May 2008
Volume 33, Issue 5B - May 2008
Volume 33, Issue 5A - May 2008
Volume 33, Issue 4C - Apr 2008
Volume 33, Issue 4B - Apr 2008
Volume 33, Issue 4A - Apr 2008
Volume 33, Issue 3C - Mar 2008
Volume 33, Issue 3B - Mar 2008
Volume 33, Issue 3A - Mar 2008
Volume 33, Issue 2A - Feb 2008
Volume 33, Issue 2C - Feb 2008
Volume 33, Issue 2B - Feb 2008
Volume 33, Issue 1C - Jan 2008
Volume 33, Issue 1B - Jan 2008
Volume 33, Issue 1A - Jan 2008
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Packet Interference and Aggregated Throughput of Bluetooth Piconets Using an Adaptive Frequency Hopping in Rician Fading Channels
Kim, Seung-Yeon ; Yang, Sung-Hyun ; Lee, Hyong-Woo ; Cho, Choong-Ho ;
The Journal of Korean Institute of Communications and Information Sciences, volume 33, issue 7B, 2008, Pages 469~476
In this paper we analyze the packet interference probability and the aggregated throughput of a WPAN in which a number of Bluetooth piconets share the ISM band with WLANS. Using an Adaptive Frequency Hopping algorithm, when the AFH is employed, the number of hops available to the Bluetooth piconets varies depending on the number of independent WLANs within the piconet's radio range. Using a packet collision model in a piconet cluster, we give an analysis of the packet interference probability and the aggregated throughput as a function of the available hops for the AFH algorithm. We also present an analytical model of packet interference with multi-path fading channel in a cluster of piconets. Through analysis, we obtain the packet collision probability and aggregated throughput assuming capture effect. Numerical examples are given to demonstrate the effect of various Parameters such as capture ratio, Rice factor and cluster size on the system performance.
TCP Performance Improvement Scheme Using 802.11 MAC MIB in the Wireless Environment
Shin, Kwang-Sik ; Kim, Ki-Won ; Yoon, Jun-Chul ; Kim, Kyung-Sub ; Jang, Mun-Suck ; Choi, Sang-Bang ;
The Journal of Korean Institute of Communications and Information Sciences, volume 33, issue 7B, 2008, Pages 477~487
Congestion control of the TCP reduces transmission rate when it detects packet loss because packet loss origines from congestion in the wired network. In the wireless network, packet loss comes from channel errors. Wired TCP degrades performance when there are wireless losses because it does not classify type of loss. These day, there are many researches which classify type of loss between congestion loss and wireless loss for wired-wireless hybrid network. For wireless TCP, many of existing algorithms are based on the estimated bandwidth or variations of packet arrival time. In this paper, we propose a new TCP scheme to distinguish the wireless packet losses from the congestion packet losses using MIB of the IEEE 802.11 MAC. We perform excessive simulations using the NS-2 network simulator and analyze the simulation results to compare the performance of the proposed algorithm to other well-known algorithms. From simulation results, we know that proposed algorithm improves performance about 12% and 32% compared with Spike algorithm and mBiaz algorithm, respectively.
Clustering Formation and Topology Control in Multi-Radio Multi-Channel Wireless Mesh Networks
Que, Ma. Victoria ; Hwang, Won-Joo ;
The Journal of Korean Institute of Communications and Information Sciences, volume 33, issue 7B, 2008, Pages 488~501
Convergence of various wireless systems can be cost effectively achieved through enhancement of existing technology. The emergence of Wireless Mesh Network (WMN) entails the interoperability and interconnection of various wireless technologies in one single system. Furthermore, WMN can be implemented with multi-radio and multi-channel enhancement. A multi-radio, multi-channel wireless mesh network could greatly improve certain networking performance metrics. In this research, two approaches namely, clustering and topology control mechanisms are integrated with multi-radio multi-channel wireless mesh network. A Clustering and Topology Control Algorithm (CTCA)is presented that would prolong network lifetime of the client nodes and maintain connectivity of the routers.
Energy Efficient Dynamic S-MAC Protocol for Sensor Networks
Yoo, Dae-Suk ; Choi, Seung-Sik ;
The Journal of Korean Institute of Communications and Information Sciences, volume 33, issue 7B, 2008, Pages 502~509
Wireless sensor networks consist of sensor nodes which are expected to be battery-powered and hard to replace or recharge. Thus, reducing the energy consumption of sensor nodes is an important design consideration in wireless sensor networks. For the implementation of energy-efficient MAC protocol, Sensor-MAC based on IEEE 802.11 protocol. In this paper, which has energy efficient scheduling, was proposed. In this paper, we propose Dynamic S-MAC that is dynamically operated by network-traffic states. Dynamic S-MAC protocol improves energy consumption of S-MAC due to change the frame length according to network-traffic states. Using NS-2 Simulation, we compare the performance of Dynamic S-MAC with S-MAC protocol.
TRaffic-Aware Topology Control Algorithm in Wireless Sensor Networks
Jung, Yeon-Su ; Choi, Hoon ; Baek, Yun-Ju ;
The Journal of Korean Institute of Communications and Information Sciences, volume 33, issue 7B, 2008, Pages 510~517
In wireless sensor networks, a number of nodes deployed in dense manner should be self-configured to establish a topology that provides communication and sensing coverage under stringent energy constraints. To establish an efficient topology, we propose the TRaffic-Aware Topology control (TRAT) algorithm that reduces energy dissipation by considering total amount of data flows in the network. Our algorithm controls the number of active nodes with traffic information and adjusts nodal transmission power by estimating amount of data flows. According to the result, the proposed algorithm shows about 30% better performance than the other methods in terms of energy efficiency.
Improvement of Tag Collection Performance for Active RFID Systems
Yoon, Won-Ju ; Chung, Sang-Hwa ; Moon, Young-Sik ;
The Journal of Korean Institute of Communications and Information Sciences, volume 33, issue 7B, 2008, Pages 518~527
Tag collection is one of the major functions in Radio Frequency Identification (RFID) systems. IS0/IEC 18000-7 defines the tag collection algorithm using the anti-collision algorithm, based on the framed slotted ALOHA for active RFID systems. However, it has inefficiency problems that reduce tag collection performance by deciding non-optimum slot size or using point-to-point commands to put collected tags to sleep. In this paper, we propose two mechanisms to overcome the inefficiency problems and improve tag collection performance: 1) a new slot size decision mechanism to allow the reader to choose the optimum slot size flexibly and 2) a broadcast-based sleep mechanism to put collected tags to sleep effectively. We also implemented an active RFID system, composed of an active RFID reader and multiple tags, and the reader is designed to maximize tag collection performance when the proposed mechanisms are applied. In experiments, we evaluated the tag collection performance using one reader and 50 tags in the real-world environment. The experimental results show that when two mechanisms are applied and the initial number of slots is chosen appropriately, the performance of the proposed tag collection algorithm is greatly enhanced, compared with that of the standard.
Dynamic Jop Distribution Algorithm for Reducing Deadlock & Packet Drop Rate in NoC
Kim, Woo-Joo ; Lee, Sung-Hee ; Hwang, Sun-Young ;
The Journal of Korean Institute of Communications and Information Sciences, volume 33, issue 7B, 2008, Pages 528~537
This paper proposes a dynamic job distribution algorithm in a hybrid NoC structure which can improve system network performance by reducing deadlock and packet drop rate for various multimedia applications. The proposed job distribution algorithm schedules every job to the sub-cluster where packet drop rate can be minimized for each multimedia application program. The proposed Job distribution algorithm and network topology targets multimedia applications frequently used in modern embedded systems, such as MPEG4 and MP3 decoder, GPS positioning system, and OFDM demodulator. Experimental results show that packet drop rate was reduced by about 13.0%, and chip area was increased by about 2.7% compared to the APSRA algorithm. When compared to the XY algorithm popularly used for benchmarking, the packet drop rate was reduced by about 23.9%, while chip area was increased by about 3.0%.
Policy-based Channel Sensing Architecture and Algorithms for Cognitive Radio Networks
Na, Do-Hyun ; Hao, Nan ; Yoo, Sang-Jo ;
The Journal of Korean Institute of Communications and Information Sciences, volume 33, issue 7B, 2008, Pages 538~549
Recently IEEE 802.22 WG has considered Cognitive Radio (CR) technology to overcome shortage of communication channels. For using CR technology, accurate and rapid sensing method selection is extremely important. According to the channel sensing method, it is of the utmost importance because it can affect the incumbent system protection. So, optimum selection of channel sensing method is very important. IEEE 802.22 gives the solution, name of fine sensing, but the solution can not adapt to various networks. So in this paper we propose Policy-based Channel Sensing Architecture and Algorithms for Cognitive Radio Networks. The proposed channel sensing architecture and algorithms can reduce both primary system detection time and quiet time in our simulation. Among the proposed sensing algorithm, channel division round robin sensing reduce average detection time up to 70% compare to fine sensing method in IEEE 802.22.
A Routing Method Using Swarm Intelligence in MANETs
Woo, Mi-Ae ; Dong, Ngo Huu ; Roh, Woo-Jong ;
The Journal of Korean Institute of Communications and Information Sciences, volume 33, issue 7B, 2008, Pages 550~556
Swam intelligence refers that a large group of simple and unsophisticated entities work together to achieve complex and significant tasks. Researches using such swarm intelligence has been performed in the network routing area. Expecially, it has been well known that routing in mobile ad-hoc networks whose features are dynamic topology and routing based on the local information is one of the applications of swarm intelligence. In this paper, we propose an ant-based routing method for MANET. The proposed method sets its goals to reduce overheads by managing ants efficiently, and to reduce route set up time. The results obtained from simulations proved that the proposed method provides shorter path set-up time and end-to-end delay and less overhead while providing comparable packet delivery ratio.
SNMP-based Management for Mobile Network Devices
Kwak, Deuk-Whee ; Lee, Hyun-Yong ; Kim, Jong-Won ;
The Journal of Korean Institute of Communications and Information Sciences, volume 33, issue 7B, 2008, Pages 557~566
Some types of network nodes such as mobile network node, mobile access point, and ad-hoc network node can be relocated frequently and, by the nature of its usage, are deployed over broad area. In this environment, the network topology is changed constantly since even the manager node as well as the managed nodes can leave or join the management network frequently. The many of existing network management technologies are mostly for small sized and homogeneous networks with static topologies and not proper for the mobile network devices. In this paper, employing peer-to-peer (P2P), the secure group communication techniques, and simple network management protocol (SNMP), we propose a highly secure and available management technique that can be used to manage the mobile network nodes through insecure management network such as the Internet. The proposed technique is implemented to show that it is practically usable.
Optimization of Coverage Extension in OFDMA Based MMR System
Kim, Seung-Yeon ; Kim, Se-Jin ; Ryu, Seung-Wan ; Lee, Hyong-Woo ; Cho, Choong-Ho ;
The Journal of Korean Institute of Communications and Information Sciences, volume 33, issue 7B, 2008, Pages 567~574
In this paper, we propose an optimal coverage extension scheme in the OFDMA based mobile multi-hop relay system. First, we propose an optimal frequency and time assignment scheme for maximizing system throughput and analyze the frame efficiency of schemes. Then, under the given BS capacity, we find the maximum number of relay hops that can be used to estimate the maximum coverage area of a BS in a multi-hop relay system. Analytical results show that the proposed scheme is efficient in coverage extension and throughput maximization in OFDMA based multi-hop relay system. Our work may be a rough guideline to control the parameters for multi-hop relay system optimization.
Patient Monitoring System Base on U-Healthcare
Jung, Won-Soo ; Oh, Young-Hwan ;
The Journal of Korean Institute of Communications and Information Sciences, volume 33, issue 7B, 2008, Pages 575~582
The existing patient monitoring system when the patient want own information. The patient confirm information through the medical institution. But the patient monitoring system based on the U-Healthcare, the patient always confirms own information through the mobile device including rfid reader. The patient need RFID middleware design to provide wanting service when the RFID reader read patient's tag information. The RFID middleware is consisted of RFID module, ARM processor and RS-232 interface. The RFID module is used to be inputted user information and RS-232 interface pass information by RFID middleware. Also, This system is embodied by specific patient monitoring system using embedded exclusive use ARM processor. In this paper introduces concept and action principle of RFID middleware and embodied patient monitoring system that use Qt.
Distortion Minimization Resource Allocation Scheme for Multiuser Video Transmission Over OFDM Network with Proportional Rates
Ha, Ho-Jin ; Yim, Chang-Hoon ; Kim, Young-Yong ;
The Journal of Korean Institute of Communications and Information Sciences, volume 33, issue 7B, 2008, Pages 583~591
This paper proposes a resource allocation algorithm for minimizing the overall distortion of multiple users in orthogonal frequency division multiplex (OFDM). The proposed algorithm exploits the diversity of multiuser and the rate-distortion function using packet distortion model in a system with limited resources. We first induce a rate-distortion function considering error concealment and error propagation properties of H.264 video structures. Then we perform adaptive resource allocation utilizing multiuser diversity for minimizing the overall video quality degradation. We also consider the proportional rate which is pre-determined for each user. Simulation results show that compared to the previous time division multiple access method and the resource allocation method maximizing data rate, the proposed rate allocation algorithm substantially improves the received video quality.
Hybrid Scaling Based Dynamic Time Warping for Detection of Low-rate TCP Attacks
So, Won-Ho ; Yoo, Kyoung-Min ; Kim, Young-Chon ;
The Journal of Korean Institute of Communications and Information Sciences, volume 33, issue 7B, 2008, Pages 592~600
In this paper, a Hybrid Scaling based DTW (HS-DTW) mechanism is proposed for detection of periodic shrew TCP attacks. A low-rate TCP attack which is a type of shrew DoS (Denial of Service) attacks, was reported recently, but it is difficult to detect the attack using previous flooding DoS detection mechanisms. A pattern matching method with DTW (Dynamic Time Warping) as a type of defense mechanisms was shown to be reasonable method of detecting and defending against a periodic low-rate TCP attack in an input traffic link. This method, however, has the problem that a legitimate link may be misidentified as an attack link, if the threshold of the DTW value is not reasonable. In order to effectively discriminate between attack traffic and legitimate traffic, the difference between their DTW values should be large as possible. To increase the difference, we analyze a critical problem with a previous algorithm and introduce a scaling method that increases the difference between DTW values. Four kinds of scaling methods are considered and the standard deviation of the sampling data is adopted. We can select an appropriate scaling scheme according to the standard deviation of an input signal. This is why the HS-DTW increases the difference between DTW values of legitimate and attack traffic. The result is that the determination of the threshold value for discrimination is easier and the probability of mistaking legitimate traffic for an attack is dramatically reduced.
Analysis on the Application of Railway Screening Effect in the Multi-conductor Line Solution of Induced Voltage to Telecommunication Lines by Electrified Traction System
Lee, Sang-Mu ; Choi, Mun-Hwan ; Cho, Pyoung-Dong ;
The Journal of Korean Institute of Communications and Information Sciences, volume 33, issue 7B, 2008, Pages 601~607
The induced voltages by AT power feeding system of electrified traction line to telecommunication line are calculated with the method of multi-conductor line solution in the CCITT Directives. There is a screening effect by railway line itself among various shielding factors against induction. It is the argue point whether the multi-conductor line solution contains the railway line effect since the calculation method does not show any expression about shielding factors. So this paper illuminates the mysterious question by reviewing the shielding factor principle on traction system, scrutinizing the Japanese bible about induction, analyzing the multi-conductor line solution itself, and comparing the result calculation considering the effect of railway screen. This paper concludes that multi-conductor line solution contains the screening effect of railway lines.