• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.13 no.3
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• pp.47-53
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• 2013

In this paper, we propose an incremental cooperative transmission protocol in two-way underlay cognitive radio networks. In the proposed protocol, two secondary sources attempt to transmit their packet to each other with help of a secondary relay under interference constraint. For performance evaluation, we derive exact closed-form expressions of average outage probability over Rayleigh fading channel. Then, we perform Monte Carlo simulations to verify the derivations. Results present that the simulation and theoretical results are in good agreement and the outage performance of the proposed protocol is better than that of two-way direct transmission protocol.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.4
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• pp.692-700
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• 2012

The WiMedia Alliance has specified a Distributed Medium Access Control (D-MAC) protocol based on UWB for high speed wireless home networks and Wireless USB. In this paper, firstly, the fair SoQ-based Distributed Reservation Protocol (DRP) for D-MAC is analyzed. And a novel SoQ-based relay transmission protocol is proposed to overcome DRP conflicts fast. In the proposed protocol, each device executes the Satisfaction of QoS (SoQ) time slot allocation algorithm independently. And, in order to give the loser device due to DRP conflicts another chance to maintain QoS resources, the proposed relay transmission protocol helps the device reserve another indirect link maintaining the required QoS resources via a relay node.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39C no.9
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• pp.789-800
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• 2014

In this paper, we propose a cooperative protocol of relay-based WUSB/DRD and WLP device in WSS of ship area WiMedia environment. For this purpose, we investigate a RNT table configuration and algorithm of RNS relay node used in relay-based cooperative communication. Then, we describe a device that makes up WLP network and propose a cooperative protocol for WUSB/DRD/WLP device communication. The proposed cooperative protocol can communicate with WUSB/DRD/WLP devices by using standard DRP reservation and WUSB DRP reservation.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.14 no.3
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• pp.7-12
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• 2014

The data forwarding transmission is an important function of the relay in cooperative communication in wireless communication systems. However, additional relay cause the waste of power consumption and cost. Therefore, in this paper, we consider how to use the user mobile devices in stead of relays to deal with this problem. In this paper, we proposed the protocol that divide each relay into two states of idle and non-idle. The receiver has two functions of base station and user mobile device. In this case, it is possible that no additional cost, and improve the spectral efficiency and network capacity. We verified BER performance for the proposed protocol over Rayleigh fading through Monte-Carlo simulation.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2010.11a
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• pp.278-281
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• 2010

협력 통신을 위한 프로토콜로 제안된 Hybrid relaying은 Source로부터 relay로 전송된 정보의 복호 성공 여부에 따라 증폭 후 전송 (AF) 기법과 복호 후 전송 (DF) 기법을 선택적으로 이용하여 전송한다. 최근 초고속 근거리 무선통신을 위한 테라 헤르츠 대역의 반송파를 이용한 연구가 활발해 지면서 Rician fading 채널 기반의 통신 기법 연구들이 중요 해 지고 있다. 본 논문에서는 각 노드간의 채널환경이 Rician fading 으로 모델링 되는 경우에 Hybrid relaying을 이용한 협력통신 기법의 outage probability를 분석한다.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.8 no.2
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• pp.23-28
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• 2008

In this paper, we propose location-aided cooperative routing protocol (LACARP) for supporting power saving and stable route lifetime in mobile ad-hoc wireless sensor networks. The main ideas and features of the proposed routing protocol are as follows. First, the definition of the area of route search using location-based information to support power saving transmission. Second, the expect zone-based establishment of routing route within the area of route search. Third, the cooperative-aided transmission method. In the operation of data transmission over the established rout the datas are transmitted via both the established route and cooperative route aided by neighbor nodes. The performance evaluation using OPNET(Optimized Network Engineering Tool) shows the LACARP can improve the packet delivery ratio and power saving transmission efficiently.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.3
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• pp.354-361
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• 2011

In this paper, we propose a spectrum sharing system that enable secondary user's spectrum access in cooperative communication scheme. At phase 1, a transmitter in primary system broadcasts signals to the rest nodes. And then, at phase 2, a transmitter in secondary system combines the decoded signals after received from a transmitter in primary system and its own signal. And then transmitter of secondary system broadcasts the combined signals to receivers of primary and secondary systems. At this time, due to the process of combining signals, receivers of primary and secondary systems experiences a performance degradation. Therefore, we propose a novel adaptive incremental decode-andforward(AIDF) protocol to overcome this problem. By using AIDF protocol, we show performance improvement of total system through various simulations.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.45 no.4
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• pp.31-37
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• 2008

Conventional cooperative communications can attain gain of spatial diversity and path loss reduction because destination node independently received same signal from source node and relay node located between source node and destination node. However, these techniques bring about decreased spectral efficiency with relay node and increased complexity of receiver by using maximal ratio combining (MRC). This paper has proposed cooperative ARQ protocol that can improve the above problems and can get the better performance. This method can increase the spectral efficiency than conventional cooperative communication because if the received signal from source node is satisfied by the destination preferentially, the destination transmits ACK message to both relay node and source node and then recovers the received signal. In addition, if ARQ message indicates NACK relay node operates selective retransmission and we can increase reliability of system compared with that of general ARQ protocol in which source node retransmits data. In the proposed protocol, the selective retransmission and ARQ message are to be determined by comparing log-likelihood ratio (LLR) computation of received signal from source node with predetermined threshold values. Therefore, this protocol don't waste redundant bandwidth with CRC code and can reduce complexity of receiver without MRC. We verified spectral efficiency and BER performance for the proposed protocol through Monte-Carlo simulation over Rayleigh fading plus AWGN.

• Journal of Broadcast Engineering
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• v.17 no.1
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• pp.95-107
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• 2012

Network coding was proposed to increase the achievable throughput of multicast in a network. Recently, combining network coding into user cooperation has attracted research attention. For cooperative transmission schemes with network coding, users combine their own and their partners messages by network coding. In previous works, it was shown that adaptive DF with network coding can achieve diversity gain and additional throughput gain. In this paper, to improve performance of conventional protocols and maximize advantage of using network coding, we propose a new network coding based user cooperation scheme which uses adaptively amplify-and-forward and decode-and-forward according to interuser channel status. We derive outage probability bound of proposed scheme and prove that it has full diversity order in the high SNR regime. Moreover, based on the outage bound, we compute optimal power allocation for the proposed scheme.

• Journal of the Korea Convergence Society
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• v.8 no.2
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• pp.21-26
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• 2017

As the Internet-related products are launched in a variety of ways, if the products are not produced according to the world standardization model of the Internet, communication with the standardized products will not be smoothly performed. This study was carried out in order to improve the competitiveness of export by launching the global standardization promotion strategy of the Internet of things, to grasp the internet standardization trends of each country and to release the following products. This research work presents a strategic driving model that can enhance interoperability among heterogenous IoT devices. Therefore, this research proposed case by case strategic standard approach based on level of technologies.