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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
Selecting the target year
Sphere Decoding Algorithm Using Two-Level Search
Huynh, Tronganh ; Cho, Jong-Min ; Kim, Jin-Sang ; Cho, Won-Kyung ;
The Journal of Korean Institute of Communications and Information Sciences, volume 33, issue 12A, 2008, Pages 1133~1137
Sphere decoding is considered as one of the most promising methods for multiple-input multiple-output (MIMO) detection. This paper proposes a novel 2-level-search sphere decoding algorithm. In the proposed algorithm, symbol detection is concurrently performed on two levels of the tree search, which helps avoid discarding good candidates at early stages. Simulation results demonstrate the good performance of the proposed algorithm in terms of bit-error-rate (BER).
Long-term Fading Statistics-Based Power Allocation for Fixed Decode-and-Forward Relays
Kong, Hyung-Yun ; Bao, Vo Nguyen Quae ;
The Journal of Korean Institute of Communications and Information Sciences, volume 33, issue 12A, 2008, Pages 1138~1146
This paper considers 2-hop wireless cooperative communications networks with fixed decode-and-forward relays. Specifically, we first derive the closed-form BER expression for theoretically evaluating the end-to-end performance of these networks. Then, based on this expression and long-tenn fading statistics, we propose a power allocation method for source and relay. Such a method brings about multiple advantages in tenn of spectral efficiency and implementation complexity over other power allocation methods based on instantaneous fading statistics. A variety of numerical results reveal that the cooperative communications scheme with the proposed power allocation significantly outperforms that with the equal power allocation and the direct transmission scheme for any position of the relay subject to the same total transmit power constraint.
An Exact BER Analysis of Dual-Hop MIMO Decouple-and-Forward Relaying with Orthogonal Space-Time Block Codes
Lee, Jae-Hoon ; Kim, Dong-Woo ;
The Journal of Korean Institute of Communications and Information Sciences, volume 33, issue 12A, 2008, Pages 1147~1155
In this paper, we derive the probability density function (PDF) of end-to-end signal-to-noise ratio (SNR) for t he dual-hop MIMO (Multiple-Input Multiple-Output) DCF (Decouple-and-Forward) system. We also provide the end-to-end bit error ratio (BER) with M-ary PSK constellations for four antenna combinations. These are (1,8,1), (8,1,8), (2,4,2), and (4,2,4). Each number in the parentheses is the number of the transmit antenna at the source, the transmit and receive antenna at the relay and the receive antenna at the destination, respectively. We show t hat the end-to-end BER expression with M-ary PSK constellations makes an exact match with numerical results. We also show that MIMO DCF relay system achieves spatial diversity.
A Bi-directional Coding using Time Reversal Mirror in Relay Systems
Kwon, Yang-Soo ; Yoo, Jae-Ho ; Kim, Hyeon-Su ; Chung, Jae-Hak ;
The Journal of Korean Institute of Communications and Information Sciences, volume 33, issue 12A, 2008, Pages 1156~1164
In this paper, we propose a bi-directional coding method (BTC) using time reversal mirror for effective data exchange between mobile stations and basestations. In conventional relay systems, while one node transmits data, other nodes should keep silent to avoid interference. Thus, to interchange data between basestations and mobile stations, it needs four stages. However, using the proposed BTC method, a relay station transmits a probe source before data transmission, and using this information, mobile stations and basestations transmit data to the relay station simultaneously. Therefore, since it exchanges data in only two steps, the system achieves improved system capacity. In addition, owing to no need for complex calculation, the relay system can be implemented with low complexity. The simulation results demonstrate that the proposed method achieves enhanced system capacity.
Pilot Emitting AF Relays and Its Applications to Beamforming
Joung, Jin-Gon ; Lee, Chang-Soo ; Lee, Yong-Hoon ;
The Journal of Korean Institute of Communications and Information Sciences, volume 33, issue 12A, 2008, Pages 1165~1171
In this paper, a pilot emitting amplify-and-forward relay and its beamforming schemes, OBF (overall beamforming) and RBF (hop-by-hop beamforming), are proposed for two-hop relaying systems. The OBF performs beamforming with respect to a overall channel from a source node (SN) to a destination node (DN) through a relay node (RN), while the proposed RBF performs two independent beamformings: from the SN to the RN and from the RN to the DN. From our analytic and numerical results, it is shown that bit-error-rate (BER) performance of the proposed RBF is better than that of the OBF scheme since the RBF system can estimate channel more proper than the CBF system, which is verified by deriving and comparing the mean square errors of the channel estimation.
Implementation of Dual-Mode Channel Card for SDR-based Smart Antenna System
Kim, Jong-Eun ; Choi, Seung-Won ;
The Journal of Korean Institute of Communications and Information Sciences, volume 33, issue 12A, 2008, Pages 1172~1176
In this paper, we describe the implementation and performance of a dual-mode Software Define Radio (SDR) smart antenna base station system. SDR technology enables a communication system to be reconfigured through software downloads to the flexible hardware platform that is implemented using programmable devices such as Digital Signal Processors (DSPs), Field Programmable Gate Arrays (FPGAs), and microprocessors. The presented base station channel card comprises the physical layer (pHY) including the baseband modem as well as the beamforming module. This channel card is designed to support TDD High-Speed Downlink Packet Access (HSDPA) as well as Wireless Broadband Portable Internet (WiBro) utilizing the SDR technology. We first describe the operations and functions required in WiBro and TDD HSDPA. Then, we explain the channel card design procedure and hardware implementation. Finally, we evaluate WiBro and TDD HSDPA performance by simulation and actual channel-card-based processing. Our smart antenna base-station dual-mode channel card shows flexibility and tremendous performance gains in terms of communication capacity and cell coverage.
Adaptive Modulation Method using Non-Line-of-Sight Identification Algorithm in LDR-UWB Systems
Ma, Lin Chuan ; Hwang, Jae-Ho ; Choi, Nack-Hyun ; Kim, Jae-Moung ;
The Journal of Korean Institute of Communications and Information Sciences, volume 33, issue 12A, 2008, Pages 1177~1184
Non-line-of-sight (NLOS) propagation can severely weaken the accuracy of ranging and localization in wireless location systems. NLOS bias mitigation techniques have recently been proposed to relieve the NLOS effects, but positively rely on the capability to accurately distinguish between LOS and NLOS propagation scenarios. This paper proposes an energy-capture-based NLOS identification method for LDR-UWB systems, based on the analysis of the characteristics of the channel impulse response (CIR). With this proposed energy capture method, the probability of successfully identifying NLOS is much improved than the existing methods, such as the kurtosis method, the strongest path compare method, etc. This NLOS identification method can be employed in adaptive modulation scheme to decrease bit error ratio (BER) level for certain signal-to-noise ratio (SNR). The BER performance with the adaptive modulation can be significantly enhanced by selecting proper modulation method with the knowledge of channel information from the proposed NLOS identification method.
Precoding for Multiuser MIMO Broadcast Channels
Lee, Min ; Oh, Seong-Keun ;
The Journal of Korean Institute of Communications and Information Sciences, volume 33, issue 12A, 2008, Pages 1185~1190
In this paper, we propose an simplified successive minimum mean square error (
) algorithm that can simplify the computational complexity for precoding matrix generation in the successive minimum mean square error (SMMSE) precoding method, which is adopted as a multiuser multiple-input multiple-output (MU-MIMO) precoding technique in the IST (information society technologies)-WINNER (wireless world initiative new radio) project. The original algorithm generates the precoding matrix by calculating all individual precoding vectors with each requiring its own MMSE nulling matrix, over all receive antennas for all users. In contrast, this proposed algorithm first calculates the MMSE nulling matrix for each user, and then calculates all precoding vectors for respective receive antennas of the corresponding user by using the identical MMSE nulling matrix, in which only a simple matrix-vector multiplication is required for each vector. Consequently, it can simplify significantly the computational complexity to generate a precoding matrix for SMMSE precoding.
Staggered Resource Allocation Scheme for Co-Channel Interference Mitigation in a Cellular OFDMA System
Son, Jun-Ho ; Min, Tae-Young ; Kang, Chung-G. ;
The Journal of Korean Institute of Communications and Information Sciences, volume 33, issue 12A, 2008, Pages 1191~1199
We propose the Staggered-zone Resource Allocation (SRA) in order to relax throughput decrease problems by the co-channel interference of the cell boundary users at the cellular OFDMA system using frequency reuse factor K=1 and analyze the throughput improvement. The proposed algorithm allocates the resources to the users in compliance with resource allocation rule which is planned in order to minimize co-channel interference between cells without any additional information. The resource allocation method in the SRA lines up the users in pathloss order as descending series, and then allocates from pre-determined resource allocation region where decides differently in each cell. This algorithm prevents the co-channel interferences of the cell boundary user to be caused by using same resource simultaneously and equalizes interference to the users in the cell.
Employing Soft Handover in TD-SCDMA systems and Its Performance Evaluation
Park, Jae-Hyun ; Xue, Peng ; Kim, Duk-Kyung ;
The Journal of Korean Institute of Communications and Information Sciences, volume 33, issue 12A, 2008, Pages 1200~1208
In TD-SCDMA systems based on TDD, when mobiles move to cell from cell, Baton Handover was used to maintain an ongoing call. But baton handover has a great demand for the equipment and system. Then both hard handover and baton handover are used alternativly in real systems. But ratio of handover success in real system is 95% which is too low to be used in systems. This paper proposes to employ Soft Handover in TD-SCDMA systems which has performed in WCDMA systems. Also we carry out the simulation, which get result of the BER performance between baton handover method and proposed handover method. The proposed method is forward to be better performance than those of the baton and hard handover.
Power based scheduling for Collaborative MIMO system
Kim, Young-Joon ; Lee, Jung-Seung ; Baik, Doo-Kwon ;
The Journal of Korean Institute of Communications and Information Sciences, volume 33, issue 12A, 2008, Pages 1209~1216
In order to maximize spectrum efficiency and data rate MIMO(Multiple Input Multiple Output) is adopted to wireless system. OFDM-based WiMAX and LTE accommodate MIMO as mandatory technology. STC(Space Time Coding) and SM(Spatial Multiplexing) are used in downlink while in uplink C-MIMO(Collaborative MIMO) is used to improve data throughput. In this paper conventional pairing schemes, RPS(Random Pairing Scheduling) and DPS(Determinant Pairing Scheduling) are analyzed. From the analysis the performance of DPS algorithm is better than that of RPS because DPS measures orthogonal factor between paired users. However, there are potential problems such as hardware complexity and performance. To overcome the issues Power-Based Scheduling(PBS) algorithm is proposed for C-MIMO. PBS can provide higher performance compared to RPS and dramatically reduce hardware complexity compared to DPS
Carrier Tracking Loop Design Using FLL-assisted PLL Scheme for Galileo L1F Channel
Choi, Seung-Duk ; Lee, Sang-Kook ; Hawng, In-Kwan ; Shin, Cheon-Sig ; Lee, Sang-Uk ;
The Journal of Korean Institute of Communications and Information Sciences, volume 33, issue 12A, 2008, Pages 1217~1224
The carrier tracking has to be basically completed for accurate positioning of Galileo satellite system. The FLL for tracking frequency errors is robust to dynamic stress causing changes of propagation time but hardly tracks accurate carrier tracking. The PLL for tracking phase errors provides accurate carrier tracking but is sensitive to dynamic stress and its tracking performance is decreased when high dynamics exist. In this paper, we design the carrier tracking loop with the FLL-assisted PLL loop filter and co-operations of FLL and PLL to achieve accurate carrier tracking in high dynamic stress. we prove the performance of designed carrier tracking loop via simulations.
Diurnal Effect Compensation Algorithm for a Backup and Substitute Navigation System of GPS
Lee, Young-Kyu ; Lee, Chang-Bok ; Yang, Sung-Hoon ; Lee, Jong-Koo ; Kong, Hyun-Dong ;
The Journal of Korean Institute of Communications and Information Sciences, volume 33, issue 12A, 2008, Pages 1225~1232
In this paper, we describe a compensation method of diurnal effect which is one of the factors giving large effect on the performance when using ground-wave signals like Loran-C for a backup and substitute navigation system of global satellite navigation system such as GPS, and currently many researches of the topics are doing in USA and in Europe. In order to compensate diurnal effect, we find periodic frequency components by using the Least Square Spectral Analysis (LSSA) method at first and then compensate the effect by subtracting the estimated compensation signal, obtained by using the estimated amplitude and phase of the individual frequency component, from the original signal. In this paper, we propose a simple compensation algorithm and analysis the performance through simulations. From the results, it is observed that the amplitude and phase can be estimated with under 5 % and 0.17 % in a somewhat poor receiving situation with 0 dB Signal to Noise Ratio (SNR). Also, we analyze the obtainable performance improvement after compensation by using the measured Loran-C data. From the results, it is observed that we can get about 22 % performance improvement when a moving average with 5 minutes interval is employed.
Design and Performance Evaluation of MIMO Antenna for Handheld Devices
Moon, Hyo-Sang ; Jun, Kye-Suk ; Lee, Bom-Son ;
The Journal of Korean Institute of Communications and Information Sciences, volume 33, issue 12A, 2008, Pages 1233~1241
We design, fabricate, and measure a MIMO antenna system mountable on a small PCB (such as UMPC). The proposed antenna system accommodates three radiation elements on the PCB area of
. Two of them employ a slot type and one uses a modified monopole with an inverted L shape expecting high isolation and polarization purity. The bandwidth of each proposed MIMO antenna ranges from 80MHz and 200MHz at the center frequency of 1.8 GHz. The isolations between ports have been found to be greater than 10dB over the interested frequency band. Besides, the proposed MIMO system has been evaluated in terms of ARC(Active Reflection Coefficient, TARC(Total ARC), correlation, MEG, and etc. The envelope correlation is calculated to be much less than 0.04 and the ratio of the mean effective gain(MEG) between the antennas is found to be close to unity.
Prediction of the Intermodulation Interference on the AMPS Receiver Exposed to Radiation from the Low Power Radio Devices
Kim, Che-Young ; Kim, Dang-Oh ;
The Journal of Korean Institute of Communications and Information Sciences, volume 33, issue 12A, 2008, Pages 1242~1250
In this paper, we predicted the radiation field strength from the low power radio devices to force the radio interference on the AMPS receiver. The predicted value of 79.13[
] is the upper value of radiation against the intermodulation interference emanated from the low power radio devices. To show the validity of the suggested values theoretical analysis on intermodulation and modeling of the AMPS receiver are performed, and also measurements on the AMPS receiver IC are carried out. The resultant numerals show the good match between them within the allowable tolerances.
Transmission Characteristics of Indoor Infrared Diffuse Links Employing Three-Beam Optical Transmitters and Non-Imaging Receivers
Wang, Zan ; Pan, Jae-Kyung ;
The Journal of Korean Institute of Communications and Information Sciences, volume 33, issue 12A, 2008, Pages 1251~1260
Diffuse wireless optical communication offers more robust optical links in terms of coverage and shadowing than line-of-sight links. However, traditional diffuse wireless infrared (IR) transceiver systems are more susceptible to multi-path distortion and great power decrease, which results in limiting high-speed performance. Multi-beam is an effective technique to compensate for multi-path distortion in a wireless infrared environment. The goal of this paper is to analyze the transmission characteristics by replacing traditional diffuse system (TDS) which contains single wide angle transmitter and single element receiver by system consisting of three-beam transmitter and non-imaging receiver (TNS) attached with compound parabolic concentrator (CPC). In the simulation, we use the recursive model developed by Barry and Kahn and build the scenario based on 10 different cases which have been listed in Table 1. Moreover, we also check the reliability of the TNS diffuse link channel by BER test on the basis of different receiver positions and room sizes. The simulation results not only show the basic transmission characteristics of TNS diffuse link, but also are references to design more efficient and reliable indoor infrared transmission systems.
Implementation of the Wireless Transducer Interface Module and NCAP architecture
Oh, Se-Moon ; Keum, Min-Ha ; Kim, Dong-Hyeok ; Kim, Jin-Sang ; Cho, Won-Kyung ;
The Journal of Korean Institute of Communications and Information Sciences, volume 33, issue 12A, 2008, Pages 1261~1269
This paper presents an implementation of the Network Capable Application Processor (NCAP) and the Wireless Transducer Interface Module (WTIM) architectures based on the new IEEE P1451.5 standard. Proposed architecture is implemented using a computer for NCAP, an FPGA board, a sensor board and two radio modules, which communicate through the ZigBee wireless communication technology between the NCAP and the WTIM based on the IEEE 1451.0 and the IEEE 1451.5 interfaces. In this paper, two experiments has been done to verify operations of proposed architecture. From the experimental results, we verify that the proposed architecture performs the wireless sensor communication functions efficiently.