• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.4A
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• pp.423-428
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• 2004

High-data rate and high speed communication techniques are required for wireless mobile communication systems to provide multimedia services. A multiple antenna technology may be used to meet this demand. In this paper, a method for performance improvement of a WCDMA downlink system using space time block coding is proposed in quasi-static Rayleigh fading channels. The proposed receiver uses the cross correlation matrix obtained by each finger corresponding to multi paths. To obtain maximum diversity gain, the inverse of cross correlation matrix and the Hermitian matrix of the channel matrix for each path arc computed, and then applied to received signals. Various simulation results show that the proposed receiver outperforms a conventional receiver in Rayleigh fading channels.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.10A
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• pp.997-1005
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• 2008

In this paper, we propose an efficient space-time block coding (STBC) scheme in a cooperative satellite-terrestrial system. The proposed STBC scheme has code rate 1 for a 3 transmit antenna scheme. Because the channel matrix of the proposed scheme is orthogonal, we can use a simple linear decoding algorithm and also can expect improved performance over the conventional scheme. The simulation results demonstrate that the proposed scheme has improved performance for bit error rates (BER) than several conventional STBC schemes. In addition, we investigate performance simulation results by power imbalance between the terrestrial repeaters and satellite.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.15 no.5
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• pp.1031-1037
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• 2011

Pilot symbol assisted modulation (PSAM) can be used for the channel estimation in orthogonal frequency division multiplexing (OFDM) transmission systems. However, imperfect channel estimates in PSAM systems degrade the bit error rate (BER) performance. I derive the BER of PSAM OFDM systems over time dispersive fading channels. The BER performance of OFDM systems with SFBC antenna diversity are analyzed, where data is transmitted over time and frequency selective Rayleigh fading channel. The performance of this PSAM SFBC OFDM systems, gauged by the average bit error rate, is analyzed considering the channel estimation error.

• Journal of Broadcast Engineering
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• v.23 no.2
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• pp.293-301
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• 2018

In ISDB-T, which is Japanese digital terrestrial TV specification based on OFDM technology, 6MHz bandwidth is divided into 13 segments. Twelve segments (full-seg) are used for high definition broadcasting for fixed receivers and one segment (one-seg) for mobile receivers. Though one-seg supports high speed mobility by using QPSK modulation, it is not suitable for large display mobile devices because of its low data rate. Full-seg using 64QAM modulation also suffers from its low mobile performance. In this paper, mobile performance of ISDB-T full-seg receiver is evaluated by applying sub-carrier interference removing scheme, high speed mobile channel estimation scheme and antenna diversity scheme.

• Animal Systematics, Evolution and Diversity
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• v.36 no.4
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• pp.285-295
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• 2020

Adults of Prosimulium kiotoense and Twinnia japonensis were collected and reported from Korea for the first time. Since adult black flies are notorious for morphological homogeneity particularly in female, larval and pupal characters have been mainly used to identify them. Adults of P. kiotoense can be identified by the following combination of characteristics: Adult, wing with radial sector (Rs) branched into R²⁺³ and R⁴⁺⁵; hind leg basitarsus without calcipala; first tarsomere without pedisulcus. Female, claw without basal thumblike lobe; hypogenial valve elongate, convex, heavily sclerotized medially, posterior end touching each other, space between valves rhomboid. Male, claw with basal thumblike lobe; ventral plate keel shaped; gonostylus with 2-3 spinules. Adults and pupa of T. japonensis can be identified by the following combination of characteristics: Adult, antenna with 7 flagellomeres. Female, hypogenial valve broad, posterior end of valve not touching each other; cercus elongate, subquadrate; spermatheca slightly wider and long, round. Male, claw with basal thumblike lobe; gonostylus with 1 spinule; ventral plate flat. Pupa, gill of 16 filaments, arising from 3 swollen stalks; abdominal tergites without spine combs except tergites III and IV with small recurved hooks; terminal spine well developed, wavy shaped.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.17 no.3
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• pp.999-1021
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• 2023

Differential spatial modulation uses the antenna index to transmit information, which improves the spectral efficiency, and completely bypasses any channel side information in the recommended setting. A generalized distributed multiple turbo coded-cooperative differential spatial modulation based on distributed multiple turbo code is put forward and its performances in Rayleigh fading channels is analyzed. The generalized distributed multiple turbo coded-cooperative differential spatial modulation scheme is a coded-cooperation communication scheme, in which we proposed a new joint parallel iterative decoding method. Moreover, the code matched interleaver is considered to be the best choice for the generalized multiple turbo coded-cooperative differential spatial modulation schemes, which is the key factor of turbo code. Monte Carlo simulated results show that the proposed cooperative differential spatial modulation scheme is better than the corresponding non-cooperative scheme over Rayleigh fading channels in multiple input and output communication system under the same conditions. In addition, the simulation results show that the code matched interleaver scheme gets a better diversity gain as compared to the random interleaver.

• Animal Systematics, Evolution and Diversity
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• v.40 no.3
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• pp.221-253
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• 2024

Eight new species of the genus Acanthomolgus are described as external associates of octocorallian corals from Korea. As diagnostic features of these new species, A. taenichaetatus n. sp. has ribbon-like distal caudal setae; A. jei n. sp. and A. crassae n. sp. have no inner proximal expansion on the exopodal segment of female leg 5, and the former species has only three setae on the maxillule (vs. four setae in other seven species). Acanthomolgus notialis n. sp. is similar to A. oporinus n. sp. in having a rounded inner proximal expansion on the exopodal segment of female leg 5, but the latter species is distinguished from the former by having longer caudal rami which are about 1.5 times longer than wide, by having a longer inner seta of the maxilla which is three quarters as long as distal lash, and by having unequal setae on the basis of maxilliped. Acanthomolgus dokdoicus n. sp., A. rugosus n. sp. and A. triplus n. sp. appear to be similar to one another in having an ear-like inner proximal expansion on the exopodal segment of female leg 5, but the genital double-somite of the female is distinctly longer than wide in A. rugosus n. sp. (wider than long in other two species), and the third endopodal segment of the antenna is distinctly shorter than the first endopodal segment in A. triplus n. sp. (vice versa in other two species). This is the first record on the genus Acanthomolgus in the temperate West Pacific.

• Journal of Satellite, Information and Communications
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• v.2 no.2
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• pp.69-74
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• 2007

Recently, the demands for the satellite broadband mobile communication services are increased. To provide these services, mobile satellite communication systems for the passengers or crews on the high-speed moving vehicles, are being developed for the last several years especially in the Europe and North America. However, most of these systems can provide only several hundred kbps of transmission rate and this is not enough performance to provide satellite internet service for the group users such as passengers on the high-speed train. Moreover, service availability with these systems is limited to be rather low because they don't have any countermeasure scheme for the N-LOS environment which happens often along the railway. This paper describes mobile broadband satellite communication system, which is on the development, to provide high data-rate internet services to the high-speed trains. This system is applied with the inter-networking scenarios of both satellite/terrestrial network and satellite/gap-filler network so that it can provide seamless service even in the train operating environment, and these inter-networking schemes result in high service availability. And this system also has the countermeasure schemes, such as upper layer FEC and antenna diversity, for the short fading which is occurred periodically on the railway due to the power supplying structures so that it can provide high speed internet services. Mobile DVB-S2 technology which is now being standardized in the DVB is used for the forward-link transmission and DVB-RCS for the return-link.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.12A
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• pp.991-997
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• 2009

Transmit beamforming is simple method to achieve the full diversity gain that is available in multiple antenna(MIMO) wireless systems. Unfortunately, the prior condition to achieve this gain requires perfect channel knowledge at both transmitter and receiver, which is impractical on account of limited feedback link. Therefore, for the practical system, codebook based feedback scheme is often employed, where the beamforming vector is selected from the codebook to maximize the output signal-to-noise ratio (SNR) at receiver, and the receiver only sends back the index of the best beamforming vector to the transmitter. In this paper we derive analytical expression of average bit error rate (BER) for the codebook based transmit beamforming MISO system over the feedback error channel. Using this analytical result, we present optimum codebook indexing scheme to improve the performance of this system. From some selected numerical examples we show that our proposed codebook indexing scheme can provide nonnegligible performance improvements in terms of average BER over the severe feedback error channel.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.10
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• pp.31-40
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• 2013

In this paper, the spatial modulation (SM) multi-input multi-output (MIMO) system is proposed for indoor wireless local area networks (WLANs) with improved spectral efficiency. SM is suitable for high speed WLANs with avoiding the inter channel interference (ICI). Only one transmit antenna is activated in SM at each symbol interval. Therefore, it fails to attain the maximum coding gain of MIMO. The space time block code (STBC)-SM MIMO system can attain the maximum diversity gain at the expense of spectral efficiency. The proposed Golden-SM MIMO system uses the Golden code to improve the coding gain and spectral efficiency at the same time. The Golden code is adapted for STBC-SM and it makes the new code book for transmission symbols. The performance of the proposed system is compared with the conventional systems with computer simulations.