• Electronics and Telecommunications Trends
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• v.26 no.5
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• pp.74-82
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• 2011

최근 Wi-Fi Alliance는 Wi-Fi 기반의 Peer-to-Peer(P2P) 규격인 Wi-Fi Direct 기술의 발표와 함께 인증을 진행하고 있다. Wi-Fi Direct 기술은 TV, 노트북, 프린터, 카메라와 같은 휴대기기 및 모바일 단말 등에 탑재되어 Access Point(AP) 또는 라우터와 같은 별도의 장비 없이도 단말 간 직접 통신을 통하여 기기 간 콘텐츠 및 서비스를 사용할 수 있는 기반을 제공하는 기술이다. Wi-Fi Direct 기술은 빠른 전송속도와 전송거리를 제공함으로써 향후 일부 영역에서 블루투스 기술을 대체할 수 있을 것으로 기대된다. 또한 향후 Wi-Fi Direct 규격의 전체 기능을 구현한 스마트폰이 출시된다면 사용자 경험(UX)을 극대화 시킬 수 있는 혁신적인 모바일 서비스를 제공할 수 있을 것으로 기대된다. 본 고에서는 Wi-Fi Direct의 업계 동향과 Wi-Fi Direct의 동작 원리를 표준 기술 규격서를 통해 분석하여 요약 정리한다.

• Information and Communications Magazine
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• v.30 no.6
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• pp.26-32
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• 2013

Wi-Fi Direct는 Wi-Fi Alliance에서 인증한 Wi-Fi 기반기술로 AP (Access Point)나 라우터 같은 인프라장비 없이 단말 간에 직접 통신을 하는 프로토콜 방식을 의미한다. Wi-Fi Direct는 현재 스마트폰 뿐만 아니라 TV, 노트북, 프린터, 카메라와 같은 다양한 기기 등에 탑재되어 단말 간 직접 통신을 통하여 콘텐츠 및 서비스를 사용할 수 있는 기술이다. 본고에서 Wi-Fi Direct 기술을 동작 단계별로 구체적으로 살펴보고 새롭게 정의된 전력 절감 기술에 대해서도 살펴본다. 또한 Wi-Fi Direct 기반 응용 서비스를 알아본다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.5
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• pp.565-573
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• 2016

Wi-Fi Direct standard technology(Wi-Fi Peer to Peer Technical Specifications v1.2, 2010) was designed for allowing peer to peer communication between two or more devices and various products which have been currently manufactured such as smart phone and smart TV have already provided this technical function. In this technology the role of Coordinator in Wi-Fi infrastructure would be matched to GO(Group Owner) which needs relatively high energy resource and computation power due to the high probability for allowing 3rd-party connection, however, the current standard specification would be limited in terms of energy distribution because it has not included a process to determine the role of GO. To address above problem, this paper classified considerable parameters into the general parameters for the physicality of devices and the specific parameters for considering the role position depending on use-case scenario, and proposed a new method called DIVA to help efficiently determining GO role from the member devices of Wi-Fi Direct network. Furthermore the effect of this mechanism was proved via simulation-based experiments.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.11
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• pp.2218-2229
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• 2015

Recently Wi-Fi Alliance defined Wi-Fi direct, which can communicate through a direct connection between the mobile device anytime, anywhere. In Wi-Fi direct, all devices are categorized by group of owner (GO) and client. Since portability is emphasized in Wi-Fi direct devices, it is essential to control the energy consumption of a device very efficiently. In order to avoid unnecessary power consumed by GO, Wi-Fi direct standard defines two power management schemes: Opportunistic power saving scheme and Notice Of Absence (NOA) scheme. But, these two schemes do not consider the traffic pattern, so we cannot expect high energy efficiency. In this paper, we suggest an algorithm to enhance the energy efficiency of Wi-Fi direct power saving, considering the characteristics of multimedia video traffic. Proposed algorithm utilizes the statistical distribution for the size of video frames and adjusts the length of awake interval dynamically. Also, considering the inter-dependency among video frames, the proposed algorithm assigns priorities to video frames and ensures that a video frame with high priority is transmitted with higher probability than other frames with low priority. Simulation results shows that the proposed method outperforms the traditional NOA in terms with average delay and energy efficiency.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.42 no.3
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• pp.585-594
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• 2017

Wireless Docking system can provide enhanced convenience to user experience of handheld device such as smart phone by using previously deployed peripheral devises such as monitor and keyboard. In this environment, user can easily use the handheld device with variable peripheral devices at any docking system place. This system would be composed of peripherals except host computing device contrarily to previous desktop and laptop environment. For this system, Wi-Fi Alliance has been developing standard technology based on Wi-Fi Direct(Wi-Fi Peer-to-Peer Technical Specifications v1.2, 2010) technology. However, this system can make a problem which may lead to complex connectivity on handheld device due to non-compatible communication interface. To address given problem, we designed a new method of Bluetooth tunneling technology via previous Wi-Fi Direct communication, and evaluated it with experiment results.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.6
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• pp.631-639
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• 2016

Wi-Fi Direct standard technology has been widely deployed on the recently manufactured products such as smart phone, smart monitor, TV, set-top box, and gaming console, and it was published from Wi-Fi Alliance with the name of Wi-Fi Peer-to-Peer Technical Specifications (v1.4, 2014) for direct connection on the wireless communication environment. However, the connection process of this standard needs 5 to 10 seconds so it can lead to user's inconvenience as well as long delay for connection. From the focus of that this problem was derived from long discovery process composed of Scan and Find, as a result, the proposed scheme on this paper modified and adapted Scan and Find processes with reassembling steps of them for reducing the connection delay. In addition, the analysis and experiments were progressed for the evaluations of the proposed scheme.

• IEMEK Journal of Embedded Systems and Applications
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• v.10 no.4
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• pp.207-212
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• 2015

Wi-Fi Direct allows battery powered mobile devices to form a wireless ad hoc network. Since one member of the network called Group Owner (GO) takes the role of managing the network, the network lifetime is mainly affected by the energy efficiency of GO. Hence, Wi-Fi Direct defines power saving schemes that allow GO to save the energy by turning off its radio interface during the periods called absence periods. However, the Wi-Fi Direct specification does not specify how to set parameters (denoted by PS parameters) determining the schedule of the absence periods. In this paper, we therefore propose a novel traffic-aware power saving scheme for Wi-Fi Direct networks. In particular, the proposed scheme estimates the application-level traffic load and adaptively tunes the PS parameters according to the estimated value.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38B no.8
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• pp.663-671
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• 2013

Recently, the Wi-Fi Direct standard based on WLAN is getting more attention as a new technology for enabling D2D(Devide-to-Device) communications on mobile devices. However, due to limited power resource of mobile devices and, an energy inefficiency problem can be an issue. In order to solve this problem, the Wi-Fi Direct defines two power management schemes: Opportunistic scheme and Notice of Absence(NoA) scheme. However, there is no concrete description of which power management scheme would be better for when. In this paper, via comprehensive simulation studies using ns-3, we show that each scheme presents obviously different performance and energy efficiency according to data traffic patterns. We then propose more energy efficient way of dynamically switching the two power management schemes.

• Proceedings of the Korea Information Processing Society Conference
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• 2014.11a
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• pp.241-243
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• 2014

Wi-Fi Direct는 그룹 내 임시적인 AP 역할을 하는 그룹 오너를 중심으로 그룹 클라이언트들이 1:1이나 1:N으로 연결되어 통신하는 D2D(Device to Device) 기술이다. 이러한 구조로 인해 그룹 오너는 Wi-Fi Direct 네트워크 성능에 지대한 영향을 미치지만 현재 Wi-Fi Direct 표준에는 그룹 구성을 변경하는 방안이 명시되어 있지 않다. 따라서 그룹 구성을 변경하고자 할 시 처음부터 그룹을 새로 형성해야 하며, 이로 인해 QoS(Quality of Service)가 감소하는 문제점이 있다. 따라서 본 논문에서는 그룹 구성 변경 시 QoS를 보장할 수 있는 그룹 관리 방안을 제안한다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2012.10a
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• pp.7-10
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• 2012

In this thesis, Wi-Fi Direct which can communicate with other device without AP, we study how to be selected GO considering multi-user connection and we apply it to application. We give the weight how many time a device was GO and how many time the device connected with other devices in 24 hours. With this value, the device is selected to GO when other devices request the connection. We show that the application which we implemented select right GO.