• 한국정보통신학회논문지
• /
• 제24권6호
• /
• pp.751-758
• /
• 2020

사물인터넷을 비롯한 다양한 형태의 통신을 활용한 응용분야가 생겨남에 따라 통신의 형태가 다양해지고 있다. 어떠한 응용은 빠른 피드백을 요구하기도 하고, 다른 응용은 수신여부와는 상관없이 데이터를 계속 보내기도 한다. 한 방향으로 데이터를 전송하는 것은 반대 방향 응답에 의해 확인될 수 있다. 이러한 정보 교환은 양방향 통신을 형성한다. 송신자는 수신자의 응답에 따라 다음 동작을 결정하므로 빠른 응답을 제공하는 것이 중요하다. 본 논문에서는 셀룰러 네트워크에서 양방향 통신의 전송지연 성능을 향상시키기 위한 기지국 협력 전송 기법을 제안한다. 양방향 트래픽뿐만 아니라 동일한 방향의 트래픽을 가진 협력 기지국을 활용하는 양방향 통신 기법을 고안하였다. 제안한 방식을 통하여 지연 시간 성능이 향상됨을 확인하였다.

• 전기학회논문지
• /
• 제56권11호
• /
• pp.1903-1909
• /
• 2007

As the electric power industry has been revolutionarily transformed such that the distributed energy resources have been interconnected with power systems and a variety of energy service providers have been appeared, the need of Consumer Energy Portal as a core of two-way communication and service infrastructure between power suppliers and consumers has been gradually increased. Consumer Energy Portal can be thought of as a combination of hardware and software enabling two-way communication between energy service providers and equipment within the consumers' premises or a physical and logical link between consumers' in-building networks and wide-area access networks. In other words, Consumer Energy Portal can make the way the power industry has been traditionally operated the web-based way, enabling two-way interactions between energy service providers and consumers and mutual networking between end users' equipment. Thus, Consumer Energy Portal can be a kind of Service portal that provides new value-added services and efficient power operations that in the past. In this paper, for ESPs' integrated resources management, demand side management and value-added service provision, we have established the two-way access network that can gather real-time metering data using ZigBee technology and control physically networked equipment.

• 한국정보통신학회:학술대회논문집
• /
• 한국정보통신학회 2013년도 춘계학술대회
• /
• pp.941-943
• /
• 2013

스마트미터가 전력공급자와의 양방향 통신을 통하여 요금정보와 전기사용 상황을 서로 주고받기 위해서는 표준화된 통신 프로토콜이 필요하게 된다. 이 통신 프로토콜은 사용자의 인증과 보안을 해결하고 사용자측에서 소비되는 전기 사용량을 전기 공급자에게 전달하게 된다. 본 논문에서는 스마트미터의 국제통신 프로토콜이 적용된 양방향 통신 및 제어 기술, 전기 기기의 등록 및 해제를 위한 통신방식을 설계하였다.

• 한국IT서비스학회지
• /
• 제11권2호
• /
• pp.93-106
• /
• 2012

Recently, a Game Shut-down policy, partially limiting the time for the use of online game service, has been implemented in order to protect the youth from the excessive use of games by limiting their access to games in the late hours, based on the serious side effects of online games on the youth. However, the effectiveness of a Game Shut-down policy becomes a social issue. Thus, this study aims to investigate the alternative policies through the levels of the communications suggested by the theory of excellence, for the successful implementation of the policy. As a result of the study, the government and students, the recipient of those policies, need to strengthen their two-way communication in respect of the Game Shut-down policy, breaking from the existing views on the perception. The problem is that the current government's way of the communication for the Game Shut-down policy is one-way and it is aiming at achieving the objectives only. Thus, the communication in this manner will cause the side effect. 'the opportunistic violation of the system in the future', even if the students seemingly accept the system. Two-way communication will enhance the motivation for the voluntary acceptance of the system and lower the motivation for the opportunistic violation of the system. Thus, the government needs to strengthen two-way communication in the future.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• 제8권10호
• /
• pp.3409-3422
• /
• 2014

The frequency spectrum available for the wireless communication is extremely crowded. In order to improve the spectral efficiency, the two-way relay networks have aroused great attention. A simple $N^{th}$ best-relay selection criterion for the opportunistic two-way relay networks is proposed, which can be implemented easily by extending the distributed timer technique in practice, since the proposed criterion is mainly based on the channel gains. The outage performance of the proposed relay selection scheme is analyzed under the outdated channel state information (CSI), and a tight closed-form lower bound and asymptotic value of the outage probability over Rayleigh fading channels are obtained. Simulation results demonstrate that the tight closed-form lower bound of the outage probability very closely matches with simulated ones in the whole SNR region, and the asymptotic results provide good tight approximations to the simulation ones, especially in the high SNR region.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• 제8권11호
• /
• pp.4087-4102
• /
• 2014

Two-way relaying is an effective way of improving system spectral efficiency by making use of physical layer network coding. However, energy efficiency in OFDM-based bidirectional relaying with asymmetric traffic requirement has not been investigated. In this study, we focused on subcarrier transmission mode selection, bit loading, and power allocation in a multicarrier single amplified-and-forward relay system. In this scheme, each subcarrier can operate in two transmission modes: one-way relaying and two-way relaying. The problem is formulated as a mixed integer programming problem. We adopt a structural approximation optimization method that first decouples the original problem into two suboptimal problems with fixed subcarrier subsets and then finds the optimal subcarrier assignment subsets. Although the suboptimal problems are nonconvex, the results obtained for a single-tone system are used to transform them to convex problems. To find the optimal subcarrier assignment subsets, an iterative algorithm based on subcarrier ranking and matching is developed. Simulation results show that the proposed method can improve system performance compared with conventional methods. Some interesting insights are also obtained via simulation.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• 제13권2호
• /
• pp.565-581
• /
• 2019

This paper investigates the wireless powered two way relay network (WPTWRN), where two single-antenna users and one single-antenna relay firstly harvest energy from signals emitted by a multi-antenna power beacon (PB) and then two users exchange information with the help of the relay by using their harvested energies. In order to improve the energy transfer efficiency, energy beamforming at the PB is deployed. For such a network, to explore the performance limit of the presented WPTWRN, an optimization problem is formulated to obtain the achievable rate region bounds by jointly optimizing the time allocation and energy beamforming design. As the optimization problem is non-convex, it is first transformed to be a convex problem by using variable substitutions and semidefinite relaxation (SDR) and then solve it efficiently. It is proved that the proposed method achieves the global optimum. Simulation results show that the achievable rate region of the presented WPTWRN architecture outperforms that of wireless powered one way relay network architecture. Results also show that the relay location has significant impact on achievable rate region of the WPTWRN.

• 정보보호학회논문지
• /
• 제27권5호
• /
• pp.1129-1140
• /
• 2017

물리적 단방향 송신만을 허용하는 단방향 전송 시스템은 백워드 링크를 물리적으로 제거하여 외부에서 네트워크를 통한 침입을 원천 차단한다. 이러한 단방향 전송 시스템은 역방향 송신 또는 양방향 통신이 필요한 환경에서는 적용하기 어렵다. 본 논문에서는 outbound TCP 양방향 통신을 허용하는 제한적 양방향 통신 시스템(LimTway, Limited Two-way communications system)을 제안한다. LimTway는 포워드 및 백워드 단방향 링크를 사용하며, 포워드 단방향 링크는 outbound UDP 트래픽의 단방향 송신을 위해 항상 활성화 상태로 유지되는 반면, 백워드 단방향 링크는 허용된 outbound TCP 세션이 설립된 동안만 활성화된다. 백워드 단방향 링크가 활성화 상태인 기간 동안 발생할 수 있는 외부로부터의 침입을 차단하기 위해, outbound TCP 트래픽 및 outbound UDP 단방향 트래픽만을 허용하도록 소프트웨어를 설계하였다.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• 제11권3호
• /
• pp.1279-1300
• /
• 2017

In the interweave cognitive networks, the interference from the primary user degrades the performance of the cognitive user transmissions. In this paper, we propose an adaptive cooperation scheme in the interweave cognitive networks to improve the performance of the cognitive user transmissions. In the proposed scheme for the bidirectional communication of two end-source cognitive users, the bidirectional communication is completed through the non-relay direct transmission, the one-way relaying cooperation transmission, and the two-way relaying cooperation transmission depending on the limited feedback from the end-sources. For the performance analysis of the proposed scheme, we derive the outage probability and the finite-SNR diversity multiplexing tradeoff (f-DMT) in a closed form, considering the imperfect spectrum sensing, the interference from the primary user, and the power allocation between the relay and the end-sources. The results show that compared with the direct transmissions (DT), the pure one-way relaying transmissions (POWRT), and the pure two-way relaying transmissions (PTWRT), the proposed scheme has better outage performance. In terms of the f-DMT, the proposed scheme outperforms the full cooperation transmissions of the POWRT and PTWRT.

• 한국인터넷방송통신학회논문지
• /
• 제9권2호
• /
• pp.65-71
• /
• 2009

1990년대 말부터 인터넷의 급속한 발전으로 인해서 쌍방향 커뮤니케이션 광고, 홍보, 온라인 음악, 동영상 영화, e-Book 등 디지털 콘텐츠의 유통이 활발하게 이루어지고 있다. 뿐만 아니라 인터넷과 TV 의 결합으로 탄생한 IP TV 가 등장하면서 쌍방향 디지털 콘텐츠 산업이 미래의 핵심 산업으로 각광을 받고 있다. 그러나, 이러한 쌍방향이 가져다준 불법 성인광고사이트, 불법 게시판, 불법 광고의 쇼핑몰, 불법 음악 복제, 동영상 복제 등 IPTV 등장으로 인한 부정적이 측면도 항시 우리 주변에 있다는 인식도 해야한다. 예를 들면 인터넷에서 운영되던 소리바다에 대한 음악저작권 문제가 검찰로부터 기소 결정으로 인해서 디지털 문화 콘텐츠 저작권 문제가 중요한 문제로 부각되고 있다. 본 논문에서는 디지털 콘텐츠의 현황 및 문제점을 알아보고, 이러한 문제점을 해결하기위해서 지능을 이용한 쌍방향 커뮤니케이션, 광고, 홍보 등 디지털 콘텐츠의 실무사례와 학생들의 취약과목 분석을 위한 모의실험을 제안한다.