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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 36, Issue 12C - Dec 2011
Volume 36, Issue 12B - Dec 2011
Volume 36, Issue 12A - Dec 2011
Volume 36, Issue 11C - Nov 2011
Volume 36, Issue 11B - Nov 2011
Volume 36, Issue 11A - Nov 2011
Volume 36, Issue 10C - Oct 2011
Volume 36, Issue 10B - Oct 2011
Volume 36, Issue 10A - Oct 2011
Volume 36, Issue 9C - Sep 2011
Volume 36, Issue 9B - Sep 2011
Volume 36, Issue 9A - Sep 2011
Volume 36, Issue 8C - Aug 2011
Volume 36, Issue 8B - Aug 2011
Volume 36, Issue 8A - Aug 2011
Volume 36, Issue 7C - Jul 2011
Volume 36, Issue 7B - Jul 2011
Volume 36, Issue 7A - Jul 2011
Volume 36, Issue 6C - Jun 2011
Volume 36, Issue 6B - Jun 2011
Volume 36, Issue 6A - Jun 2011
Volume 36, Issue 5C - May 2011
Volume 36, Issue 5B - May 2011
Volume 36, Issue 5A - May 2011
Volume 36, Issue 4C - Apr 2011
Volume 36, Issue 4B - Apr 2011
Volume 36, Issue 4A - Apr 2011
Volume 36, Issue 3C - Mar 2011
Volume 36, Issue 3B - Mar 2011
Volume 36, Issue 3A - Mar 2011
Volume 36, Issue 2C - Feb 2011
Volume 36, Issue 2B - Feb 2011
Volume 36, Issue 2A - Feb 2011
Volume 36, Issue 1C - Jan 2011
Volume 36, Issue 1B - Jan 2011
Volume 36, Issue 1A - Jan 2011
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Carrier Frequency Offset and 2-D AoA Estimation Method for an OFDM-based Mobile Relay Station with Uniform Circular Array
Ko, Yo-Han ; Cho, Yong-Soo ;
The Journal of Korean Institute of Communications and Information Sciences, volume 36, issue 5A, 2011, Pages 423~431
DOI : 10.7840/KICS.2011.36A.5.423
In this paper, carrier frequency offset and 2-D AoA (Angle-of-Arrival) estimation methods are proposed for an OFDM-based MRS (Mobile Relay Station) with UCA (Uniform Circular Array). The proposed methods are performed by using the preamble symbol in downlink and can improve the performance of CFO estimation significantly, compared with the conventional method. The proposed methods can be divided into two methods (method 1 and method 2) depending on the order of the AoA estimation and CFO estimation. It is shown by computer simulation under Mobile WiMAX environments that the proposed methods can estimate the CFOs and AoAs of adjacent BSs effectively.
Analysis and Compensation of STO Effects in the Multi-band OFDM Communication System of TDM Reception Method
Lee, Hui-Kyu ; Ryu, Heung-Gyoon ;
The Journal of Korean Institute of Communications and Information Sciences, volume 36, issue 5A, 2011, Pages 432~440
DOI : 10.7840/KICS.2011.36A.5.432
For the 4th generation mobile communication, LTE-advanced system needs the broad frequency band up to 100MHz for providing the data rate of maximum 1Gpbs. However, it is very difficult to secure the broad frequency band in the current frequency allocation situation. So, carrier aggregation was proposed as the solution, in which several fragmented frequency bands are used at the same time. Basically, multiple parallel receivers are required to get the information data from the different frequency bands but this conventional multi-chain receiver system is very inefficient. Therefore, in this paper, we like to study the single chain system that is able to receive the multi-band signals in a single receiver based on the time division multiplexing (TDM) reception method. This proposed TDM receiver efficiently manage to receive the multi-band signals in time domain and handle the baseband signals with one DSP board. However, the serious distortion could be generated by the sampling timing offset (STO) in the TDM-based system. Therefore, we like to analyze STO effects in the TDM-based system and propose a compensation method using estimated STO. Finally, it is shown by simulation that the proposed method is appropriate for the single chain receiver and show good compensation performance.
Efficient Estimation and Compensation of CFO and STO in Multi-carrier Communication System
Lee, Hui-Kyu ; Ryu, Heung-Gyoon ;
The Journal of Korean Institute of Communications and Information Sciences, volume 36, issue 5A, 2011, Pages 441~449
DOI : 10.7840/KICS.2011.36A.5.441
Sample timing offset (STO) and carrier frequency offset (CFO) are caused by inter-symbol interference (ISI), inter-carrier interference (ICI) and phase error in orthogonal frequency division multiplexing (OFDM) system. OFDM characteristic is sensitive about STO and CFO. So when ICI occurs, compensation is hard and complex equalizer is needed. In this paper, we propose an effective correction method using feedback process with pilot and synchronization symbol. After feedback with estimated value in frequency domain, STO and CFO are corrected by control sample & and holder and oscillator. As a result of simulation, we confirm that STO and CFO can be corrected without equalizer through feedback.
Idle Channel Search Scheme for Cognitive Radio Systems Based on Probability Estimation of Channel Idleness
Son, Min-Sung ; Shin, Oh-Soon ;
The Journal of Korean Institute of Communications and Information Sciences, volume 36, issue 5A, 2011, Pages 450~456
DOI : 10.7840/KICS.2011.36A.5.450
In this paper, idle channel search schemes based on spectrum sensing are proposed for cognitive radio systems with multiple channels. Specifically, we propose a scheme for determining the order of sensing for multiple channels, for which the probability of each channel being idle is estimated every search interval. By performing sensing in the descending order of the probabilities, the time required for searching idle channels is expected to decrease. In addition, we combine the proposed scheme with a user grouping scheme to further improve the sensing performance. Simulation results show that the user grouping reduces the search time, although it degrades the reliability of detection. The proposed search scheme based on probability estimation of channel idleness is found to reduce the search time significantly as compared to the conventional random search scheme. We apply both the proposed search scheme and user grouping scheme to a cognitive radio system to validate the overall performance.
Orthogonal Reference Vectors Selection Method of Subspace Interference Alignment
Seo, Jong-Pil ; Kim, Hyun-Soo ; Ahn, Jae-Jin ; Chung, Jae-Hak ;
The Journal of Korean Institute of Communications and Information Sciences, volume 36, issue 5A, 2011, Pages 457~463
DOI : 10.7840/KICS.2011.36A.5.457
This paper proposes theorthogonal reference vectors selection method of the subspace interference alignment. The proposed method selects multiple orthogonal reference vectors instead of using one reference vector for all users at the same time. The proposed scheme selects a reference vector which maximizes a sum-rate for a certain cell, generates orthogonal vectors to the previous selected vector and selects the one of orthogonal vectors whose sum rate is maximized for each cell. Larger channel gain and sum-rate than the previous method can be obtained by selection degree of freedom. The computer simulation demonstrates the proposed method gives higher sum-rate compared with that of the previous reference vector selection method.
Performance Analysis of a Media Access Control Protocol for Magnetic Field Communication
Jeong, Eui-Hoon ; Won, Yun-Jae ; Kim, Sun-Hee ; Lim, Seung-Ok ; Bang, Young-Cheol ;
The Journal of Korean Institute of Communications and Information Sciences, volume 36, issue 5A, 2011, Pages 464~472
DOI : 10.7840/KICS.2011.36A.5.464
As wireless sensor networks are applied to various applications such as environment monitoring and disaster sensing system, there are increased needs for wireless communication in underground environment. Since the previous wireless communication technology using electromagnetic wave is not appropriate for the underground environment, a new alternative is required. Recently a magnetic field communication technology has been proposed and standardized as a domestic KS standard. In this paper, we analyze the media access control protocol of the KS standard by an analysis and a simulation study.
Performance Analysis of Joint Call Admission Control(JCAC) According to Resource Reservation Rate Changes in LTE-WLAN Heterogeneous Network Environment
Kim, Yi-Kang ; Kim, Seung-Yeon ; Ryu, Seung-Wan ; Cho, Choong-Ho ;
The Journal of Korean Institute of Communications and Information Sciences, volume 36, issue 5A, 2011, Pages 473~484
DOI : 10.7840/KICS.2011.36A.5.473
In this paper, we analyze and propose the Joint Call Admission Control(JCAC) scheme to combine network selection scheme and radio resource reservation based Call Admission Control(CAC) in LTE-WLAN heterogeneous networks. First, We propose the JCAC system that uses network decision rate to select a network for terminal and radio resource reservation scheme in overlaying LTE-WLAN network environment. And we analyze the performance of a proposed system using markov chain model. The performance is presented in terms of the new call blocking probability, handoff call dropping probability, and channel utilization of each network. As a performance result of the our research, the system using JCAC is better than the system using non-JCAC. We found a suitable resource reservation rate that is 10% in the system using JCAC. Our work may be useful as a guideline of resource reservation rate to introduce JCAC system using resource reservation scheme in overlaying LTE-WLAN network environment.
Optimal Selection of Reference Vector in Sub-space Interference Alignment for Cell Capacity Maximization
Han, Dong-Keol ; Hui, Bing ; Chang, Kyung-Hi ; Koo, Bon-Tae ;
The Journal of Korean Institute of Communications and Information Sciences, volume 36, issue 5A, 2011, Pages 485~494
DOI : 10.7840/KICS.2011.36A.5.485
In this paper, novel sub-space interference alignment algorithms are proposed to boost the capacity in multi-cell environment. In the case of conventional sub-space alignment, arbitrary reference vectors have been adopted as transmitting vectors at the transmitter side, and the inter-cell interference among users are eliminated by using orthogonal vectors of the chosen reference vectors at the receiver side. However, in this case, sum-rate varies using different reference vectors even though the channel values keep constant, and vice versa. Therefore, the relationship between reference vectors and channel values are analyzed in this paper, and novel interference alignment algorithms are proposed to increase multi-cell capacity. Reference vectors with similar magnitude are adopted in the proposed algorithm. Simulation results show that the proposed algorithms provide about 50 % higher sum-rate than conventional algorithm.
Packet Bicasting in Fast Handover for PMIPv6
Lee, Jin-Soo ; Lee, Su-Kyoung ;
The Journal of Korean Institute of Communications and Information Sciences, volume 36, issue 5A, 2011, Pages 495~501
DOI : 10.7840/KICS.2011.36A.5.495
IEFT proposed MIPv6 for supporting IP movement. Mobile Node is involved signaling that cause handover latency in MIPv6. Recently, Proxy Mobile IPv6 is proposed by IETF for network-based mobility management to reduce overhead in mobile node still suffers from packet loss. PMIPv6 can decrease handover latency which related overhead in MN by using network agent. Therefore, MIPSHOP Working Group proposed fast handover for PMIPv6, fu this paper, we proposed packet bicasting scheme on dual interface mobile node that can support fast handover using PMIPv6 schemes. Further, a numerical analysis is provided to show the benefits of our scheme. In the analysis, various parameters are used to compare our scheme with another procedure.
A Slot Scheduling Algorithm for Balancing Power Consumption in Tree-based Sensor Networks
Kim, Je-Wook ; Oh, Roon ;
The Journal of Korean Institute of Communications and Information Sciences, volume 36, issue 5A, 2011, Pages 502~510
DOI : 10.7840/KICS.2011.36A.5.502
In this paper, we propose a slot scheduling algorithm for balancing power consumption in tree-based sensor networks. In this type of networks, nodes with lower depths tend to consume more energy than those with higher depths, thereby reducing the life time of the network. The proposed algorithm allocates a series of receiving slots first and then a series of sending slots. This way of slot allocation eases packet aggregation and filtering, and thus reduces traffic load on nodes near a sink. We compare the proposed algorithm and the frame-slot allocation algorithm employed in the TreeMAC by resorting to simulation. The simulation results showed that the proposed approach well achieves the balancing of power consumption.
Two-step Scheduling With Reduced Feedback Overhead in Multiuser Relay Systems
Jang, Yong-Up ; Shin, Won-Yong ; Kim, A-Jung ;
The Journal of Korean Institute of Communications and Information Sciences, volume 36, issue 5A, 2011, Pages 511~520
DOI : 10.7840/KICS.2011.36A.5.511
In this paper, we introduce a multiuser (MU) scheduling method for multiuser amplify-and-forward relay systems, which selects both the transmission mode, i.e., either one- or two-hop transmission, and the desired user via two steps. A closed-form expression for the average achievable rate of the proposed scheduling is derived under two transmission modes with MU scheduling, and its asymptotic solution is also analyzed in the limit of large number of mobile stations. Based on the analysis, we perform our two-step scheduling algorithm: the transmission mode selection followed by the user selection that needs partial feedback for instantaneous signal-to-noise ratios (SNRs) to the base station. We also analyze the average SNR condition such that the MU diversity gain is fully exploited. In addition, it is examined how to further reduce a quantity of feedback under certain conditions. The proposed algorithm shows the comparable achievable rate to that of the optimal one using full feedback information, while its required feedback overhead is reduced below half of the optimal one.
Sensor Node Localization Scheme using Four Mobile Robots
Lee, Woo-Sik ; Kim, Nam-Gi ;
The Journal of Korean Institute of Communications and Information Sciences, volume 36, issue 5A, 2011, Pages 521~528
DOI : 10.7840/KICS.2011.36A.5.521
In sensor network environment, it is very important to localize sensor nodes. In order to know the position of nodes without GPS signals, the anchor robot approach is representatively used. Therefore, in this paper, we propose 4-Robot Localization Scheme (4RLS) that uses four mobile robots to efficiently localize sensor nodes for the fast time. Then, we show the improved performance of 4RLS in comparison with previously used three robot scheme through the real implementation and analysis.
Verification of the Possibility for Overcoming HF Skip Zone through NVIS communications
Lee, Myung-Noh ; Yoo, Jae-Young ; Rhee, Jong-Myung ;
The Journal of Korean Institute of Communications and Information Sciences, volume 36, issue 5A, 2011, Pages 529~535
DOI : 10.7840/KICS.2011.36A.5.529
The HF communication method is capable of communicating short and long distances without a separate relaying method and is used as the primary/secondary communication method in other nations. However, the Korean military strongly discouraged the use of the method due to issues regarding the skip zone and the fact that the usable frequency changes according to irregularities in the ionosphere. The NVIS communication is less susceptible to noise than typical communications using ionosphere reflection, and is also able to communicate short distances containing skip zones. In this paper, we inspect the NVIS communication methods of foreign nations in order to facilitate the use of HF communications, as well as provide solutions to the issues mentioned above. This paper explains the concept of NVIS communication, and investigates how the Korean military is implementing HF communications based on actual communications data of military corps. Based on this result, we have verified the possibility of overcoming skip zones through NVIS communications, and have considered the applicability of a prediction program in order to enhance the efficiency of HF communications.
The Efficient Detection Algorithm of Various CR signals using Channel Bonding in TV White Space
Lim, Sun-Min ; Jung, Hoi-Yoon ; Jeong, Byung-Jang ;
The Journal of Korean Institute of Communications and Information Sciences, volume 36, issue 5A, 2011, Pages 536~542
DOI : 10.7840/KICS.2011.36A.5.536
For efficient utilization of spectrum resources in TV white space after DTV transition, FCC allowed usage of the spectrum for CR system. The CR system is required to cognize channel usage state for utilizing the unused spectrum in TV white space which coexists various primary and secondary systems. In the meantime, as a demand for high throughput communication had been increased recently, CR systems also consider to adopt channel bonding technology, thus spectrum sensing for channel bonded system is essentially required. In this paper, we propose a novel spectrum sensing algorithm for channel bonding system using a single channel receiver. For IEEE 802.l1af signal, the proposed algorithm provide detection probability of 90% with false alarm probability 10% at SNR -18dB for single channel system and at SNR -7dB for 8 channel bonded system, respectively. Utilizing the proposed scheme, we can detect channel bonded signal using only a single receiver, therefore system overhead for spectrum sensing can be reduced significantly.
A Cancellation Technique of TX Leakage Signal for Emhanced Readability in UHF-band RFID Readers
Noh, Eui-Ho ; Lee, Jong-Hyuk ; Kim, Nam-Yoon ; Kim, Chang-Woo ;
The Journal of Korean Institute of Communications and Information Sciences, volume 36, issue 5A, 2011, Pages 543~550
DOI : 10.7840/KICS.2011.36A.5.543
In order to improve readability, a leakage-signal canceller has been proposed in UHF-band RFID readers. The proposed canceller is composed of two blocks: an environment monitoring block for detection of Tx and RX power levels and a leakage cancellation block. The leakage canceller consists of directional-couplers, digital attenuators and phase shifters based on the feed-forward scheme. The leakage canceller is located between antenna and reader. An improved experimental characterization of the scheme is presented with results from the reader operating in the Korean RFID frequency band, conforming the validity of the approach with more than 29 dB of leakage cancellation.