• KSII Transactions on Internet and Information Systems (TIIS)
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• v.8 no.9
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• pp.2967-2981
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• 2014

Device-to-Device (D2D) communication is a technology component for long-term evolution-advanced (LTE-A). In D2D communication, users in close proximity to each other can communicate directly without going through a base station; such direct communication can improve spectral efficiency. Although D2D communication brings improvement in spectral efficiency, it also causes interference to the cellular network as a result of spectrum sharing. In particularly, D2D communication can generate interference for each D2D pair when the common wireless medium in a co-located limited area is accessed. Even though the interference management for between the D2D pair and cellular networks has been proposed, the interference reducing methods have still not been fully studied for the D2D pairs. In this paper, we investigate the problem of D2D pair coexistence in which interference is considered between D2D pairs. Using a signal to interference model for a target D2D pair, we provide an analysis of the aggregated throughput of a dense D2D network. For a target D2D pair, we assume that the desired signal and interference signals obey multipath fading and shadow fading. Through analysis, we demonstrate the effect of cluster size such as the number of D2D pairs and the size of the considered area on the network performance. The analytical results are compared with computer simulations. Our work can be used for a rough guideline for controlling the system throughput in a dense D2D network environment.

• Proceedings of the KSR Conference
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• 2005.05a
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• pp.776-781
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• 2005

In this paper, using received channel information, we analyze performance in MIMO multiuser system in low-to-medium mobile speed by selecting each user's constellations, powers, and transmit antennas. Given a target of symbol error, we determine each user's constellations, powers, selected tranprobability smit antennas such that the required signal-to-noise(SNR) is minimized for MMSE, V-BLAST receiver according to each user's information and channel estimation information. When we do power control with antenna selection technique through uplink channels of MIMO system in low-to-medium mobile speed, we analyze system performance with wireless channel information from Base-Station(BS) to Users. By simulation, it has been shown that the proposed antenna selection scheme for transmitting data offer better performance improvement than all transmit antennas for transmitting data.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.26 no.7
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• pp.1040-1046
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• 2022

In this paper, we consider a system with massive user equipments (UEs) in a cell and assume path loss and Rayleigh fading channels between the base station (BS) and UEs. In addition, it is assumed that the system bandwidth consists of multiple identical frequency subchannels. Under such assumptions, we propose a channel state information (CSI) feedback scheme and a resource allocation scheme for non-orthogonal multiple access (NOMA) transmission in order to reduce the feedback overhead of CSI generated by massive UEs and to reduce the complexity of resource allocation. In particular, for the proposed schemes, we analyze the sum data rate achievable by massive UEs in a cell and the outage probability with which the UEs in a cell do not meet the target data rate. Through the simulation results, we show that the proposed schemes can provide the superior outage probability, although it degrades the average sum data rate.

• Journal of Korean Society for Geospatial Information Science
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• v.23 no.1
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• pp.3-14
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• 2015

As buildings in the downtown area, such as the complex building connected to the skyscraper and the underground facility, have become large and complex, the range of target domain of the space information service is rapidly expanding to the interior space; it is considered that this change will create various demands of service such as the indoor geospatial information base safety, the management of facility, and the interior navigation in the future, along with spread of mobile devices and development of IT technology. As for the indoor geospatial information, however, there is no certification standard of the established indoor geospatial information data quality, so preparing the certification standard is urgent. Thus, this study reviewed foreign and domestic research cases and prepared measures for quality verification of the indoor geospatial information to conduct a verification test of the Yeongdeungpo Station indoor geospatial information, established in 2014. As a result, through the verification test of the method and standard of the indoor geospatial information quality certification suggested by this research, it was identified that the uniform and higher quality data could be classified, and the types of error high frequently occurring could be investigated. These results are expected to be utilized as the basic data for establishing quality certification system for the indoor geospatial information in the future.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.8A
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• pp.918-927
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• 2004

WCDMA system is 3rd generation wireless mobile system specified by 3GPP. In WCDMA downlink, two power control schemes are operated. One is inner loop power control operated in every slot. Another is outer loop power control based on one frame time. Base station (BS) can estimate proper transmission power by these two power control schemes. However, because each MS's transmission power makes a severe effect on BS's performance, BS cannot give excessive transmission power to the specific user. 3GPP defined Power Control Dynamic Range (PCDR) to guarantee proper BS's performance. In this paper, we propose Adaptive PCDR algorithm. By APCDR algorithm, Radio Network Controller (RNC) can estimate each MS's current state using received signal to interference ratio (SIR). APCDR algorithm changes MS's maximum code channel power based on frame. By proposed scheme, each MS can reduce wireless channel effect and endure outages in cell edge. Therefore, each MS can obtain better QoS. Simulation result indicate that APCDR algorithm show more attractive output than fixed PCDR algorithm.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.43 no.11 s.353
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• pp.85-94
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• 2006

Simple-relay aided resource allocation (SRARA) schemes are incorporated with throughput guarantee scheduling (TGS) in IEEE 802.16 type TDD-OFDMA downlink to enhance service coverage, where the amount of resources at each relay is limited due to either its available power which is much smaller than base station (BS) power or the required overhead The performance of SRARA schemes is evaluated with both proportional fair (PF) and TGS schedulers at 64 kbps and 128 kbps user throughput requirements. For SRARA with RSs of relatively lower power, a scheme putting total power into only one subchannel shows larger coverage than when both subchnnels are used in a manner of equal power allocation, while the RS with evenly power-allocated two subchannels could provide larger coverage gain for a relatively higher power. In a lower target (64kbps), more improvement comes from relay scheme rather than scheduler design. For a relatively higher level (128 kbps), it comes from scheduler design rather than relay.

• Asian-Australasian Journal of Animal Sciences
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• v.19 no.6
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• pp.775-778
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• 2006

Sarabi cows (n = 136) from the Sarabi Breeding Station were genotyped at bovine lymphocyte antigen (BoLA)-DRB3.2 locus by a genotyping system that used the polymerase chain reaction and restriction fragment length polymorphism. Genomic DNA was extracted from whole blood samples. A two-step polymerase chain reaction was carried out in order to amplify a 284 base-pair fragment of target gene. Nested-PCR products were digested with three restriction endonuclease enzymes RsaI, BstYI and HaeIII. Digested fragments were analyzed by polyacrylamide gel electrophoresis. Twenty-six BoLA-DRB3.2 alleles were identified with frequencies ranging from 0.4 to 15.1%. Six new allele types observed in this study have not been reported previously. Identified alleles include: BoLA-DRB3.$2^*1$, $^*2$, $^*4$, $^*6$, $^*8$, $^*12$, $^*13$, $^*14$, $^*15$, $^*16$, $^*17$, $^*23$, $^*24$, $^*25$, $^*28$, $^*32$, $^*34$, $^*35$, $^*36$, $^*37$, $^*42$, $^*46$, $^*51$, $^*kba$, $^*laa$ and $^*vaa$. Their frequencies were found to be 0.4, 0.4, 0.7, 11.4, 1.1, 1.8, 2.9, 2.2, 4.4, 9.6, 1.1, 13.6, 0.4, 0.4, 1.1, 0.7, 0.4, 6.2, 2.2, 3.7, 1.1, 7.7, 1.5, 15.1, 2.6 and 7.3% respectively. The six most frequent alleles (DRB3.2 $^*6$, $^*16$, $^*23$, $^*46$, $^*kba$ and $^*vaa$) accounted for 64.7% of the alleles in the population of this herd. Numerous studies on this locus, covering different breeds, has revealed the existence of various alleles in this locus, and new investigations have introduced novel alleles. With respect to the high number of the observed alleles in this survey and the novelty of some alleles with no previous record of reporting, it is plausible to conclude that the BoLA-DRB3.2 locus is highly polymorphic in Iranian native Sarabi cows.