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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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Complexity Limited Sphere Decoder and Its SER Performance Analysis
Jeon, Eun-Sung ; Yang, Jang-Hoon ; Kim, Bong-Ku ;
The Journal of Korean Institute of Communications and Information Sciences, volume 33, issue 6A, 2008, Pages 577~582
In this paper, we present a scheme to overcome the worst case complexity of the sphere decoder. If the number of visited nodes reaches the threshold, the detected symbol vector is determined between two candidate symbol vectors. One candidate symbol vector is obtained from the demodulated output of ZF receiver which is initial stage of the sphere decoder. The other candidate symbol vector consists of two sub-symbol vectors. The first sub-symbol vector consists of lately visited nodes running from the most upper layer. The second one contains corresponding demodulated outputs of ZF receiver. Between these two candidate symbol vectors, the one with smaller euclidean distance to the received symbol vector is chosen as detected symbol vector. In addition, we show the upper bound of symbol error rate performance for the sphere decoder using the proposed scheme. In the simulation, the proposed scheme shows the significant reduction of the worst case complexity while having negligible SER performance degradation.
Design and Performance Evaluation of an Advanced CI/OFDM System for the Reduction of PAPR and ICI
Ryu, Heung-Gyoon ;
The Journal of Korean Institute of Communications and Information Sciences, volume 33, issue 6A, 2008, Pages 583~591
OFDM (orthogonal frequency division multiplexing) has serious problem of high PAPR (peak-to-average power ratio). Recently, CI/OFDM (carrier interferometry OFDM) system has been proposed for the low PAPR. However, CI/OFDM system shows another problem of ICI because of phase offset mismatch due to the phase noise. In this paper, to simultaneously reduce the PAPR and ICI effects, we propose an A-CI/OFDM (advanced-CT/OFDM). This method improves the BER performance by use of the margin of phase offset at CI codes. Propose system to reduce the effect the phase noise, even though it shows a little bit higher PAPR than conventional CI/OFDM, so we apply the PTS among the PAPR reduction techniques to proposed system to mitigate this problem. Therefore, it improves the total BER performance because the proposed method can decrease the effect of phase noise and get the gain in PAPR reduction performance. From the simulation results, we can show the performance comparison between the conventional OFDM, CI/OFDM and A-CI/OFDM.
A Novel Pilot-Aided Integer Frequency Offset Estimation Scheme for OFDM-Based Systems
Lee, Young-Yoon ; Kim, Sang-Hun ; Han, Tae-Hee ; Yoo, Seung-Hwan ; Kim, Sun-Yong ; Yoon, Seok-Ho ;
The Journal of Korean Institute of Communications and Information Sciences, volume 33, issue 6A, 2008, Pages 592~598
In this paper, a novel pilot-aided integer frequency offset estimation scheme is proposed for orthogonal Sequency division multiplexing (OFDM)-based digital video broadcasting (DVB) systems. The conventional pilot-aided integer frequency offset estimation scheme proposed for OFDM-based DVB systems exploits the partial information of combinations provided by pilots. Thus, in this paper, we propose a novel integer frequency offset estimation scheme exploiting all information of pilot combinations. To compare the performance of the proposed scheme with that of the conventional scheme, we conduct a simulation in additive white Gaussian noise (AWGN) and multipath Rayleigh channels, which shows that the proposed scheme outperforms the conventional scheme in terms of the probability of integer frequency offset estimation failure.
3GPP GERAN Evolution System Employing High Order Modulation and Turbo Coding: TSC for Channel Estimation
Lee, Jong-Hwan ; Hwang, Eun-Sun ; Choi, Byoung-Jo ; Hwang, Seung-Hoon ; Choi, Jong-Soo ;
The Journal of Korean Institute of Communications and Information Sciences, volume 33, issue 6A, 2008, Pages 599~606
In this paper, the channel estimation performance of proposed TSC (TSC-S) is investigated in terms of the BER and BLER performances when HSR is considered for GERAN evolution system. The performance is evaluated by the link level simulation and is compared with the other TSC proposal (TSC-E). Numerical results show that the performance employing the TSC-S is almost same to that using the TSC-E. In the case of cochannel interferences, the similar tendency is shown, when joint least square is adopted for channel estimation.
3GPP GERAN Evolution System Employing High Order Modulation and Turbo Coding: Symbol Mapping Based on Priority
Oh, Hyeong-Joo ; Choi, Byoung-Jo ; Hwang, Seung-Hoon ; Choi, Jong-Soo ;
The Journal of Korean Institute of Communications and Information Sciences, volume 33, issue 6A, 2008, Pages 607~613
In this paper, we investigate the performance of SMP-assisted 3GPP GERAN evolution system employing high order modulation and turbo coding. When applying the SMP which maps systematic bits into highly reliable bit positions, it is confirmed that there is the performance gain for the modulation and coding schemes of 16QAM(DAS-8) as well as 32QAM(DAS-11) by link level simulation.
Low Complexity QRD-M MIMO Detection Algorithm Based on Adaptive Search Area
Kim, Bong-Seok ; Choi, Kwon-Hue ;
The Journal of Korean Institute of Communications and Information Sciences, volume 33, issue 6A, 2008, Pages 614~623
A very low complexity QRD-M algorithm based on adaptive search area is proposed for MIMO systems. The conventional QRD-M scheme extends each survivor paths to all constellation symbols at each layer and selects M paths of minimum path metrics. We found that performance will not be degraded even if we adaptively restrict the survivor path extension only to the neighboring points of temporary detection symbol according to the channel condition at each layer. By employing this feature, we propose a new QRD-M algorithm achieving the near MLD performance with a reduced complexity. We employ the channel gain ratio among the layers as a channel condition indicator, which does not require SNR estimation. The simulation results show that the proposed scheme effectively achieves near MLD performance while maintaining the overall average computation complexity much smaller than the conventional QRD-M algorithm.
Fast Group Scanning Scheme in IEEE 802.16e Networks
Choi, Jae-Kark ; Yoo, Sang-Jo ;
The Journal of Korean Institute of Communications and Information Sciences, volume 33, issue 6A, 2008, Pages 624~634
The mobile station which is about to do handover in IEEE 802.16e networks scans its neighboring base station channels to decide its next target base station. However, due to the lack of location information of its subscribers, the serving base station cannot provide any reliable candidate channel which is actually attachable by the scanning mobile stations, which makes the mobile station suffer from the long scanning time. Sometimes, long scanning time may cause the degradation of quality of service due to repeatable scan-duration or failure to start the handover procedure in time. To overcome these problems, in this paper, we propose a new protocol so called fast group scanning scheme, in which multiple mobile stations form a group to scan their neighboring base station channels simultaneously. Main contribution of this proposal is to find and decide a reliable target base station within a short scanning time. The fast group scanning scheme can be deployed to the cell network of the serving base station with a dynamic neighboring base station list management.
Optimum Power Allocation for Distributed Antenna Systems with Large Scale Fading-only Feedback
Lim, Dong-Ho ; Choi, Kwon-Hue ;
The Journal of Korean Institute of Communications and Information Sciences, volume 33, issue 6A, 2008, Pages 635~642
We propose the Optimum Power Allocation (OPA) scheme for Distributed Antenna Systems(DAS) in the time-varying Rayleigh fading channel. Recently, the OPA schemes which uses the Channel State Information (CSI) including a small scale (fast) fading have been proposed. However, the channel is changing vary fast over time due to small scale fading, therefore Bit Error Rate (BER) increases. Because of this reason, we derive the OPA for minimizing BER in DAS, which only uses a large scale fading to CSI and excepts a small scale fading. The simulation results show that the proposed OPA achieves better BER performance than conventional OPA considering a small scale fading in time-varying Rayleigh fading channel, and also has similar performance in Rayleigh flat-fading environment. The BER performance of proposed OPA which derived in Rayleigh fading channel is similar to minimum BER of Ricean fading channel which has small Line-of-Sight (LOS).
Performance Analysis of Proportional Fair Scheduling with Partial Feedback Information for Multiuser MIMO-OFDMA Systems
Kang, Min-Gyu ; Byun, Il-Mu ; Park, Jin-Bae ; Kim, Kwang-Soon ;
The Journal of Korean Institute of Communications and Information Sciences, volume 33, issue 6A, 2008, Pages 643~651
In this paper, we analyze the performance of normalized SNR based proportional fair scheduling with partial feedback information for multiuser MIMO-OFDMA systems. The closed form expression on the downlink capacity of the selective partial CQI feedback scheme is derived and its asymptotic behavior is investigated. From the performance analysis and numerical results, it is found that the optimal growth rate of downlink capacity can be achieved with bounded average feedback overhead irrespective of the number of users.
Random Access Scheme With Multiple Slots
Rim, Min-Joong ; Shin, Young-Joo ; Lim, Dae-Woon ;
The Journal of Korean Institute of Communications and Information Sciences, volume 33, issue 6A, 2008, Pages 652~658
In this paper, a new random access scheme is proposed to improve the probability of successful access. In the conventional scheme, a packet is transmitted by a user using one slot and considered successfully transmitted if a collision does not occur. In comparison, a packet of the proposed scheme is transmitted by a user using one or more slots and considered successfully transmitted if there is at least one slot without collision. We evaluate the optimal number of slots selected by users to maximize the probability of successful access when the probability distribution functions for the number of users are given such as Binomial and Poission distribution. From the numerical analysis, it is shown that the proposed scheme performs better than conventional scheme.
A Random Access Scheme Robust to Timing Offsets for Uplink OFDMA Systems
Song, Hyun-Joo ; Rim, Dae-Woon ; Jeong, Byung-Jang ; Noh, Tae-Gyun ; Rim, Min-Joong ;
The Journal of Korean Institute of Communications and Information Sciences, volume 33, issue 6A, 2008, Pages 659~665
If ranging processes are not frequent in an uplink OFDMA system, the timing synchronization between base and mobile stations may not be maintained. Especially in the case of infrequent random accesses in a large cell, timing offsets can be considerable and the destroyed orthogonality of OFDMA signals may result in the degraded performance. This paper proposes a novel random access scheme for uplink OFDMA systems, which support the orthogonality of OFDMA signals with timing offsets by allowing a random access OFDMA symbol shorter than a normal one. In order to make uplink OFDMA systems robust to timing offsets, the proposed scheme inserts a zero-padding region in an OFDMA symbol.
Optimal Power and Spectrum Allocation Scheme in Multicell WRAN
Hwang, In-Kwan ; Lim, Yeon-Jun ; Cho, Hae-Keun ; Song, Myoung-Sun ;
The Journal of Korean Institute of Communications and Information Sciences, volume 33, issue 6A, 2008, Pages 666~675
The IEEE 802.22 standard is being developed with the target of improving the efficiency of spectrum utilization and importing the new wireless communication service. The WRAN standard based on Cognitive Radio is being processed for sharing TV bands. In this paper, the efficient spectrum allocation scheme and the optimal power allocation scheme, Partial Constant Power Water Filling (PCPWF), are proposed to maximize the channel capacity and spectrum efficiency and minimize the interference between adjacent cells. And we maximize the system throughput and fairness by using proposed dynamic cell plan that efficiently allocates channel. The results of the simulations are presented to verify the utilization of our proposed scheme.
Adaptive Channel Estimation Algorithm for DVB-T
Kim, Seung-Hwan ; Lee, Jin-Beom ; Lee, Jin-Yong ; Kim, Young-Lok ;
The Journal of Korean Institute of Communications and Information Sciences, volume 33, issue 6A, 2008, Pages 676~684
In digital video broadcasting-terrestrial (DVB-T), which is the European digital terrestrial television standard, the orthogonal frequency division multiplexing (OFDM) has been adopted for signal transmission. The main reasons using OFDM are to increase the robustness against the frequency selective fading and impulse noise, and to use available bandwidth efficiently. However, channel variation within an OFDM symbol destroys orthogonality between subcarriers, resulting in inter-carrier interference (ICI), which increases an error floor in proportional to maximum Doppler spread. This paper provides an ICI analysis in both time and frequency domains while existing literatures analyze the ICI effects mainly in frequency domain and proposes the algorithms that estimate the channel impulse response and channel variation using least square (LS) algorithm which is the most simple channel estimation technique. And we propose adaptive channel estimation algorithm that estimates the velocity of terminals. The simulation results show that proposed algorithm has similar performance with about 1.5% computational complexity of noise and ICI reduction LS algorithm in low speed environments.
Design of a Timing Recovery Loop for Inmarsat Mini-m System Downlink Receiver
Cho, Byung-Chang ; Han, Jung-Su ; Choi, Hyung-Jin ;
The Journal of Korean Institute of Communications and Information Sciences, volume 33, issue 6A, 2008, Pages 685~692
In this paper, we propose a timing recovery loop for Inmarsat mini-m system downlink receiver. Inmarsat mini-m system requires a timing recovery loop which is robust in frequency offset and has fast acquisition because Inmarsat mini-m system specification requires frequency tolerance is required of
Hz (signal bandwidth: 2.4 kHz) and acquisition time of UW (Unique Word) signal duration (15ms).Therefore, we propose a timing recovery loop which is suitable for Inmarsat mini-m system. The proposed timing recovery loop adopted noncoherent UW detector and differential ELD which applied differential UW signal for stability and fast acquisition in frequency offset environment. Simulation results show that the proposed timing recovery loop has stable operation and fast acquisition in frequency offset environment for the system.