Young-Min Ko

Publications

4 Hybrid MIMO-OFDM Detection Scheme for High Performance

Authors: Hyoung-Kyu Song, Dong-Hyun Ha, Chang-Bin Ha, Young-Min Ko

Abstract:

In recent years, a multi-antenna system is actively used to improve the performance of the communication. A MIMO-OFDM system can provide multiplexing gain or diversity gain. These gains are obtained in proportion to the increase of the number of antennas. In order to provide the optimal gain of the MIMO-OFDM system, various transmission and reception schemes are presented. This paper aims to propose a hybrid scheme that base station provides both diversity gain and multiplexing gain at the same time.

Keywords: Hybrid, mimo, DFE, diversity gain, multiplexing gain

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3 An Improved Transmission Scheme in Cooperative Communication System

Authors: Seung-Jun Yu, Hyoung-Kyu Song, Young-Min Ko

Abstract:

Recently developed cooperative diversity scheme enables a terminal to get transmit diversity through the support of other terminals. However, most of the introduced cooperative schemes have a common fault of decreased transmission rate because the destination should receive the decodable compositions of symbols from the source and the relay. In order to achieve high data rate, we propose a cooperative scheme that employs hierarchical modulation. This scheme is free from the rate loss and allows seamless cooperative communication.

Keywords: Cooperative Communication, high data rate, transmission scheme, hierarchical modulation

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2 Cooperative Scheme Using Adjacent Base Stations in Wireless Communication

Authors: Seung-Jun Yu, Hyoung-Kyu Song, Chang-Bin Ha, Young-Min Ko

Abstract:

In a wireless communication system, the failure of base station can result in a communication disruption in the cell. This paper proposes a way to deal with the failure of base station in a wireless communication system based on OFDM. Cooperative communication of the adjacent base stations can be a solution of the problem. High performance is obtained by the configuration of transmission signals which is applied CDD scheme in the cooperative communication. The Cooperative scheme can be a e ective solution in case of the particular situation.

Keywords: OFDM, mimo, base station, CDD, diversity gain

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1 Cooperative CDD Scheme Based on Hierarchical Modulation in OFDM System

Authors: Seung-Jun Yu, Hyoung-Kyu Song, Yeong-Seop Ahn, Young-Min Ko

Abstract:

In order to achieve high data rate and increase the spectral efficiency, multiple input multiple output (MIMO) system has been proposed. However, multiple antennas are limited by size and cost. Therefore, recently developed cooperative diversity scheme, which profits the transmit diversity only with the existing hardware by constituting a virtual antenna array, can be a solution. However, most of the introduced cooperative techniques have a common fault of decreased transmission rate because the destination should receive the decodable compositions of symbols from the source and the relay. In this paper, we propose a cooperative cyclic delay diversity (CDD) scheme that use hierarchical modulation. This scheme is free from the rate loss and allows seamless cooperative communication.

Keywords: mimo, Cooperative Communication, CDD, hierarchical modulation

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Abstracts

8 Signaling Using Phase Shifting in Wi-Fi Backscatter System

Authors: Hyoung-Kyu Song, Chang-Bin Ha, Young-Min Ko, Seongjoo Lee

Abstract:

In this paper, the signaling scheme using phase shifting is proposed for the improved performance of the Wi-Fi backscatter system. Because the communication in the Wi-Fi backscatter system is based on on-off modulation and impedance modulation by unit of packet, the data rate is very low compared to the conventional wireless systems. Also, because the Wi-Fi backscatter system is based on the RF-powered device, the achievement of high reliability is difficult. In order to increase the low data rate, the proposed scheme transmits information of multiple bits during one packet period. Also, in order to increase the reliability, the proposed scheme shifts the phase of signal in according to the transmitting information. The simulation result shows that the proposed scheme has the improved throughput performance.

Keywords: IoT, phase shifting, RF-powered device, Wi-Fi backscatter system

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7 The Batteryless Wi-Fi Backscatter System and Method for Improving the Transmission Range

Authors: Seung-Jun Yu, Hyoung-Kyu Song, Young-Min Ko, Seongjoo Lee

Abstract:

The Internet of things (IoT) system has attracted attention. IoT is a technology to connect all the objects to the internet as well as computer. IoT makes it possible for providing more data interoperability methods for an application purpose. Among the IoT technology, the research of devices so that they can communicate without power supply has been actively conducted. Batteryless system permits us to communicate without power supply devices. In this paper, batteryless backscatter system is used as a tag. And mobile devices which are embedded wireless fidelity (Wi-Fi) chipset are used as a reader. The backscatter tag can be obtained Internet connectivity from the reader. Conventional Wi-Fi backscatter system has limitation in the transmission range. In this paper, the proposed algorithm can be obtained improved reliability as well as overcoming the limitation about transmission range.

Keywords: RFID, IoT, Wi-Fi, backscatter, Ambient RF, Batteryless communication, Energy-harvesting, Tag

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6 An Efficient Strategy for Relay Selection in Multi-Hop Communication

Authors: Seung-Jun Yu, Hyoung-Kyu Song, Jung-In Baik, Young-Min Ko

Abstract:

This paper proposes an efficient relaying algorithm to obtain diversity for improving the reliability of a signal. The algorithm achieves time or space diversity gain by multiple versions of the same signal through two routes. Relays are separated between a source and destination. The routes between the source and destination are set adaptive in order to deal with different channels and noises. The routes consist of one or more relays and the source transmits its signal to the destination through the routes. The signals from the relays are combined and detected at the destination. The proposed algorithm provides a better performance than the conventional algorithms in bit error rate (BER).

Keywords: OFDM, relay, multi-hop, relaying selection

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5 An Improved Transmission Scheme in Cooperative Communication System

Authors: Seung-Jun Yu, Hyoung-Kyu Song, Young-Min Ko

Abstract:

Recently developed cooperative diversity scheme enables a terminal to get transmit diversity through the support of other terminals. However, most of the introduced cooperative schemes have a common fault of decreased transmission rate because the destination should receive the decodable compositions of symbols from the source and the relay. In order to achieve high data rate, we propose a cooperative scheme that employs hierarchical modulation. This scheme is free from the rate loss and allows seamless cooperative communication.

Keywords: Cooperative Communication, hierarchical modulation, high data rate, transmission scheme

Procedia PDF Downloads 251
4 Cooperative Scheme Using Adjacent Base Stations in Wireless Communication

Authors: Seung-Jun Yu, Hyoung-Kyu Song, Chang-Bin Ha, Young-Min Ko

Abstract:

In a wireless communication system, the failure of base station can result in a communication disruption in the cell. This paper proposes a way to deal with the failure of base station in a wireless communication system based on OFDM. Cooperative communication of the adjacent base stations can be a solution of the problem. High performance is obtained by the configuration of transmission signals which is applied CDD scheme in the cooperative communication. The Cooperative scheme can be a effective solution in case of the particular situation.

Keywords: OFDM, mimo, base station, CDD, diversity gain

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3 Cooperative Diversity Scheme Based on MIMO-OFDM in Small Cell Network

Authors: Hyoung-Kyu Song, Dong-Hyun Ha, Chang-Bin Ha, Young-Min Ko

Abstract:

In Heterogeneous network (HetNet) can provide high quality of a service in a wireless communication system by composition of small cell networks. The composition of small cell networks improves cell coverage and capacity to the mobile users.Recently, various techniques using small cell networks have been researched in the wireless communication system. In this paper, the cooperative scheme obtaining high reliability is proposed in the small cell networks. The proposed scheme suggests a cooperative small cell system and the new signal transmission technique in the proposed system model. The new signal transmission technique applies a cyclic delay diversity (CDD) scheme based on the multiple input multiple output-orthogonal frequency division multiplexing (MIMO-OFDM) system to obtain improved performance. The improved performance of the proposed scheme is confirmed by the simulation results.

Keywords: OFDM, Cooperative Communication, diversity gain, adaptive transmission

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2 Hybrid MIMO-OFDM Detection Scheme for High Performance

Authors: Hyoung-Kyu Song, Dong-Hyun Ha, Chang-Bin Ha, Young-Min Ko

Abstract:

In recent years, a multi-antenna system is actively used to improve the performance of the communication. A MIMO-OFDM system can provide multiplexing gain or diversity gain. These gains are obtained in proportion to the increase of the number of antennas. In order to provide the optimal gain of the MIMO-OFDM system, various transmission and reception schemes are presented. This paper aims to propose a hybrid scheme that base station provides both diversity gain and multiplexing gain at the same time.

Keywords: Hybrid, mimo, DFE, diversity gain, multiplexing gain

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1 Efficient Relay Selection Scheme Utilizing OVSF Code in Cooperative Communication System

Authors: Hyoung-Kyu Song, Myoung-Jin Kim, Yeong-Seop Ahn, Young-Min Ko

Abstract:

This paper proposes a relay selection scheme utilizing an orthogonal variable spreading factor (OVSF) code in a cooperative communication. The relay selection scheme influences on the communication performance in the cooperative communication. Conventional relay selection schemes such as the best harmonic mean relay selection scheme or the threshold-based relay selection scheme should know information such as channel state information (CSI) in advance. The proposed relay selection scheme does not require information in advance by using a reference signal utilizing the OVSF code. The simulation result shows that bit error rate (BER) performance of proposed relay selection scheme is similar to the best harmonic mean relay selection scheme that is known as one of the optimal relay selection schemes.

Keywords: OFDM, Cooperative Communication, relay selection, OVSF code

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