• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.11 no.6
• /
• pp.2831-2847
• /
• 2017

In this paper, a joint destination-relay selection and antenna mode selection scheme for full-duplex (FD) relay network is investigated, which consists of one source node, N FD amplify-and-forward (AF) relays and M destination nodes. Multiple antennas are configured at the source node, and beamforming technique is adopted. Two antennas are employed at each relay, one for receiving and the other for transmitting. Only one antenna is equipped at each destination node. In the proposed scheme, the best destination node is firstly selected according to the direct links between the source node and destination nodes. Then the transmit and receive mode of two antennas at each relay is adaptively selected based on the relaying link condition. Meanwhile, the best relay with the optimal Tx/Rx antenna configuration is selected to forward the signals. To characterize the performance of the proposed scheme, the closed-form expression of the outage probability is derived; meanwhile, the simple asymptotic expressions are also obtained. Our analysis shows that the proposed scheme obtains the benefits of multi-relay diversity and multi-destination diversity. Moreover, extra space diversity in the medium SNR region can be achieved due to the antenna selection at the relay. Finally, Monte-Carlo simulations are provided to consolidate the analytical results, and show the effectiveness of the proposed scheme.

• The Korean Journal of Ecology
• /
• v.23 no.2
• /
• pp.107-112
• /
• 2000

Comparison of oribatid mite community structures among Namsan, Kwangreung, and Mt, Jumbong, which receive different levels of environmental stress from severe to almost none, was made in coniferous and deciduous forests, respectively. The number of species of oribatid mites was significantly lower in Namsan and Mt. Jumbong than in Kwangreung in the coniferous forest (p<0.05). In the deciduous forests, the number of species of oribatid mites was significantly lower in Namsan than in Kwangreung and Mt. Jumbong. Dominant species in 3 regions were remarkably different. Similarity of the oribatid community between Namsan and Kwangreung was much higher (ca. 2 times) than similarities between Namsan and Mt. Jumbong. and Kwangreung and Mt Jumbong. Diversity index (H$^{\prime}$) value of oribatid communities in deciduous forests in Namsan, Kwangreung and Mt. Jumbong was 2.74, 2.78, and 2.87, respectively. Diversity (H$^{\prime}$) value of oribatid communities in coniferous forests in Namsan, Kwangreung and Mt. Jumbong was 2.83, 2.62, and 2.38, respectively. Namsan and Kwangreung were characterized as O-type in both coniferous and deciduous forests On the contrary, Mt. Jumbong was characterized as MG-type in MGP-I analysis.

• Korean journal of communication and information
• /
• v.30
• /
• pp.175-201
• /
• 2005

This study investigates the diversity of news topic and source of the New York Times, Chicago Tribune, and the Los Angeles Times in the second half of the twentieth century. In probing the conventional traits of the contemporary press, the researcher traced the changing patterns and trends of news values in terms of news-gathering routine in order to evaluate the journalistic role conception in terms of social responsibility theory. Findings indicated that the American press as a neutral transmitter has been consistently violated by source and topic bias without any significant changes during the last five decades. The data, however, revealed the evident shift of the contemporary press from the heavy reliance of official source to the business/economic source. In addition, news topics such as business, health, and education have replaced the conventional popular topics such as crime and accidents. By contrast, it was revealed that the unconventional topics such as poverty, labor and minority still fail to receive the large attention from the target papers.

• Journal of Advanced Navigation Technology
• /
• v.14 no.2
• /
• pp.220-226
• /
• 2010

In this paper, an low power symbol detector is proposed for MIMO communication system with two transmit and two receive antennas. The proposed symbol detector can support both the spatial multiplexing (SM) mode and spatial diversity (SD) mode for MIMO transmission technique, and shows the optimal maximum likelihood (ML) performance. Also, by sharing the hardware block and using the dedicated clock MIMO modes, the power of the proposed architecture is dramatically decreased. The proposed symbol detector was designed in hardware description language (HDL) and synthesized to logic gates using a $0.13-{\mu}m$ CMOS standard cell library. The power consumption was estimated by using Synopsys Power CompilerTM, which is reduced by maximum 85%, compared with the conventional architecture.

• Journal of Communications and Networks
• /
• v.11 no.2
• /
• pp.196-206
• /
• 2009

Over the last five years, relaying or multihop techniques have been intensively researched as means for potentially improving link performance of wireless networks. However, the data rates of relays are often limited because they cannot transmit and receive on the same frequency simultaneously. This limitation has come to the attention of researchers, and recently a number of relay techniques have been proposed specifically to improve the data efficiency of relaying protocols. This paper surveys transmission protocols that employ first single relays, then multiple relays and finally multiple antenna relays. A common feature of these techniques is that novel signal processing techniques are required in the relay network to support increased data rates. This paper presents results and discussion that highlight the advantages of these approaches.

• Proceedings of the KIEE Conference
• /
• 2008.10b
• /
• pp.111-112
• /
• 2008

본 논문에서는 다중경로가 무수히 많은 환경에서 다중안테나를 이용하여 고속의 데이터 전송률을 달성하기 위한 초광대역(UWB: Ultra-Wideband) 시스템의 성능 향상에 대해 연구한다. 다중 수신안테나가 제공하는 공간다이버시티와 RAKE 수신기가 제공하는 시간 다이버시티가 2PAM(Binary Pulse Amplitude Modulation) TH(Time Hopping) UWB 통신 시스템의 성능에 미치는 영향을 분석한다. 시뮬레이션 결과를 통해 다중수신안테나의 수가 증가함에 따라 TH-UWB 시스템의 BER(Bit Error Rate) 성능이 크게 향상됨을 보인다. 또한 SRAKE(Selective RAKE)에 의해 선택되는 다중경로 성분의 수가 증가할수록 시스템의 성능이 더욱 향상 됨을 확인한다.

• KDI Journal of Economic Policy
• /
• v.27 no.2
• /
• pp.155-203
• /
• 2005

This paper intends to provide information about whichgroups should receive particular attention from policies aimed at raising participation and employment. A detailed portrait of the diversity of non-employment is presented with description of the extent the under-represented groups stayed in situations of labor inactivity. Also, once in employment, how these groups move from one sector to another is a main interest in the analysis. Using longitudinal data (1998-2002) constructed from 'the economically active population survey', I followed individuals over a five-year period and analyzed how frequently inactive persons enter the labor market and how they change industries and statuses.

• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.41 no.10
• /
• pp.17-26
• /
• 2004

This paper proposes JBSTBC (Joint Beamforming Space-Time Block Coding) scheme for MIMO (Multi-Input Multi-Output) communication systems. To enhance the order of spatial diversity in presence of deteriorative fading correlations as well as inter-substream interferences, the proposed JBSTBC method employs joint eigen-beamforming technique together with the BOLD (block-ordered layered detector) for MIMO-STBC. In order to confirm superiority of the proposed JBSTBC method, the computer simulations are conducted in highly correlated fading situations with providing detailed mathematical derivations for clarifying functionality of the proposed scheme.

• The Transactions of the Korean Institute of Electrical Engineers P
• /
• v.65 no.2
• /
• pp.136-141
• /
• 2016

This paper proposes an alternate time-switched multiplexed space-time block coding technique for orthogonal frequency division modulation systems. The traditional multiplexed space-time block coding technique can provide more data rate owing to multiple transmit and receive technique, which causes a lot of hardware burden. Alternate time-switched scheme of transmitting time-domain zeros can reduce this hardware burden by half with time-domain switches only. Simulation results show that alternate time-switched scheme has almost same performance with half of baseband and RF modules in comparison with a multiplexed space-time block coding for orthogonal frequency division modulation systems with twice repetitive transmission.

• Proceedings of the Korean Society of Broadcast Engineers Conference
• /
• 2005.11a
• /
• pp.95-98
• /
• 2005

이 논문에서는 동일채널 간섭이 존재하는 채널 환경에서 OFDM(Orthogonal Frequency Division Multiplexing) 시스템의 수신 다이버시티 결합 방법을 제시한다. 제시된 방법에서는 각 수신 안테나로부터의 수신 신호를 주파수 영역에서 부반송파 단위로 결합하며, 잡음과 간섭 전력을 고려한 MRC(Maximum Ratio Combining)를 적용한다. 잡음과 간섭 전력은 채널의 제한된 지연확산에 기인하는 주파수 대역에서의 상관특성(coherency)을 이용하여 인접한 몇 개의 부채널에 대해 잡음과 간섭 전력의 평균을 취함으로써 더 정확한 추정치를 얻는다. IEEE 802.11a 무선 LAN 규격에서 모의실험 결과 제안방법은 기존 방시에 비해 SNR을 2-4 dB 개선하였으며, 정확하게 SINR을 추정한 경우에 대해 1 dB 이내로 접근하는 결과를 나타내었다.