• Journal of the Institute of Electronics Engineers of Korea TC
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• v.41 no.3
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• pp.167-167
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• 2004

The system combined layered space-time processing and space-time trellis codes (STTC) provide high transmission rate as well as diversity and coding gain without bandwidth expansion. In this paper, two layered receiver structures are proposed. One is the LSTT-MMSE in which received bit streams are decoupled by interference nulling and then decoded by separate STTC decoders. The decoded outputs are cancelled from the received signal before advancing to the next layer detection. The other is LSTT-Whitening employing whitening rather than nulling. The receiver employing whitening process shows several advantages on diversity gain and the required number of receive antennas compare to the convolutional coded space-time processing. The proposed receivers use different decoding order scheme according to each interference suwression. The (4, 3) LSTT-Whitening receiver still achieves 1㏈ gain over the (4, 4) LSTT-MMSE and the (4, 4) coded layered space-time processing.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.41 no.3
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• pp.9-14
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• 2004

The system combined layered space-time processing and space-time trellis codes (STTC) provide high transmission rate as well as diversity and coding gain without bandwidth expansion. In this paper, two layered receiver structures are proposed. One is the LSTT-MMSE in which received bit streams are decoupled by interference nulling and then decoded by separate STTC decoders. The decoded outputs are cancelled from the received signal before advancing to the next layer detection. The other is LSTT-Whitening employing whitening rather than nulling. The receiver employing whitening process shows several advantages on diversity gain and the required number of receive antennas compare to the convolutional coded space-time processing. The proposed receivers use different decoding order scheme according to each interference suwression. The (4, 3) LSTT-Whitening receiver still achieves 1㏈ gain over the (4, 4) LSTT-MMSE and the (4, 4) coded layered space-time processing.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.47 no.3
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• pp.41-50
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• 2010

In this paper, an area-efficient symbol detector is proposed for MIMO communication systems with two transmit and two receive antennas. The proposed symbol detector can support both the spatial multiplexing mode and spatial diversity mode for MIMO transmission technique, and shows the optimal maximum likelihood (ML) performance. Also, by sharing the hardware block with multi-stage pipeline structure and using the complex multiplier based on polar-coordinate，the complexity of the proposed architecture is dramatically decreased. The proposed symbol detector was designed in hardware description language (HDL) and implemented with Xilinx Virtex-5 FPGA. With the proposed architecture, the number of logic slices for the proposed symbol detection is 52490 and the number of DSP48s (dedicated multiplier) is 52, which are reduced by 35.3% and 85.3%, respectively, compared with the conventional architecture.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38A no.8
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• pp.733-738
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• 2013

In this paper, we consider a physical layer security of an amplify-and-forward (AF) transmission in a presence of an eavesdropper in a wiretap channel. The proposed wiretap channel consists of a source, a destination, a relay, and an eavesdropper. Specifically, we consider that the relay has multiple antennas to exploit a diversity gain and a receive/transmit antenna selection schemes are applied to maximize a signal-to-noise ratio. In a practical point of view, we focus on the practical scenario where the relay does not have any channel state information of the eavesdropper while performing an AF protocol at the relay. For a secrecy performance analysis, we analyze a secrecy outage probability of the proposed system in one-integral form and verify our analysis with the computer-based simulation.

• Journal of KIISE:Information Networking
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• v.33 no.3
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• pp.269-276
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• 2006

This paper proposes a seamless handover scheme for high-speed trains using dual mobile routers to minimize service disruption time and packet loss during handovers. In the proposed scheme, each of the dual mobile routers is located at each end of the moving network for space diversity. One of the two mobile routers can continuously receive packets from its home agent, while the other is undergoing a handover, but they act as one logical mobile router. Analytical and simulation results showed that the proposed scheme could provide no service disruption or packet losses during handovers.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.5
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• pp.974-979
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• 2009

The BER performance of a MIMO detection scheme on frequency selective Rayleigh fading channels is analytically discussed. The presented MIMO detection scheme consists of temporal and spatial combiners followed by a ZF detector. It is shown that for a MIMO system with $N_T$ transmit antennas, $N_R$ receive antennas, and L resolvable multipath components, it achieves the diversity order of $LN_R-N_T+1$. In frequency selective Rayleigh fading channels, an analytical error rate expression of the systems is also provided and the analytical error performance is compared with the simulated results.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.4A
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• pp.418-425
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• 2008

In this paper, we propose two different types of cooperative transmission protocols, referred to as spatial multiplexing with receive diversity (SMRD), that are bandwidth-efficient. We show that the BER performance can be significantly improved with a proper design of SMRD protocol under the AF (Amplify-and-Forward) and the DF (Decode-and-Forward) modes of relaying, when there is no interference among all symbols transmitted in the same time slot. BER analysis and our simulation result show that the proposed transmission protocol achieves a significant gain over no-cooperation (direct transmission) without any bandwidth expansion.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2013.05a
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• pp.586-589
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• 2013

In this paper, the proposed scheme is STBC system combined with convolutional code to ensure the reliability of data transmission for a high rate wireless communication. In addition, this scheme uses a modified viterbi algorithm in order to get a high system gain when data is transmitted. Because we combine STBC and comvolutional code, the proposed scheme can get a diversity gain of STBC and coding gain of convolutional code at the same time. Unlike existing viterbi docoding algorithm using Hamming distance in order to calculate branch matrix, the modified viterbi algorithm uses Euclidean distance value between received symbol and reference symbol. To analyze the system proposed, it was simulated by changing the constraint length of the convolutional code and the number of transmit and receive antennas of STBC.

• Journal of electromagnetic engineering and science
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• v.10 no.4
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• pp.270-275
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• 2010

In a conventional opportunistic transmit (COT) cooperative relaying system, only the relays that receive signal-to-noise ratio (SNR) from the source and that exceed the threshold transmit to the destination. The COT system, however, only considers the SNR of the source-relay (S-R) path regardless that the SNR of the relay-destination (R-D) path is the opportunistic transmission condition. For that reason, it is not guaranteed that all the transmitted signals from relays exceed the threshold at the destination. Therefore we propose a double opportunistic transmit (DOT) cooperative relaying system - when both of the received SNR from a source and from a destination exceed the threshold, the relay transmits to the destination. It is shown that the proposed DOT system reduces power consumption by 6.9, 20.9, 32.4, and 41.4 % for K =3, 5, 7, and 9, respectively under the given condition of $P_{out}=1{\times}10^{-3}$ and $\overline{\gamma}_{SR}/\Gamma_{SR}$=30 dB, compared to the COT system. We noticed that the performance of the DOT system is superior to that of the COT system for the identical number of active transmit relays under the same condition of the normalized average SNR of $\overline{\gamma}_{RD}/\Gamma_{RD}$.

• Journal of Contemporary Eastern Asia
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• v.19 no.2
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• pp.125-147
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• 2020

On the World Refugee Day in 2017, Yao Chen, a Chinese actress, philanthropist, and social media influencer, posted messages in her Weibo in support of the United Nations Refugee Agency (UNHCR). Yet, social media users quickly interpreted this supportive message of the refugee program as encouraging people to "accept and receive refugees" (jieshou nanmin) into China. Particularly, the category of Middle Eastern refugees elicited most criticism in China's cyberspace. As the inclusion of refugees is an integral part of immigrant multiculturalism, this article examines the limits of multicultural imagination of refugees―particularly those from the Middle Eastern and North Africa―in contemporary China. I argue that the limits of multicultural imagination in contemporary China is profoundly shaped by an intricate interweaving of domestic policies and global imaginaries toward refugees. By deploying a mixed methodology, such limits are examined from legal-institutional, ideological, and sociocultural perspectives. More specifically, three interrelated aspects will be highlighted in the article: (1) the global circulation of right-wing populism imaginaries, and their entanglements with the anti-Muslim sentiments in contemporary China; (2) the current insufficiency of the legal-institutional framework regarding refugees and asylum-seekers, which needs to be contextualized in China's modern history of dealing with refugee issues; (3) population politics, the rise of Han-centric nationalism, and their constraining impact on the interpretation of historical events related to cultural diversity. In conclusion, this article also offers potential implications for further examining the different yet potentially intersected genealogies of multicultural imaginaries beyond the Middle Eastern and North African refugees in Asia.