• 한국콘텐츠학회논문지
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• 제10권3호
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• pp.32-43
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• 2010

IPTV(Internet Protocol Television)는 다양한 멀티미디어 콘텐츠를 인터넷을 통하여 TV로 제공하는 방송과 통신이 융합된 기술이다. 방송을 송신하는 측은 멀티캐스트 방식으로 스크램블된 방송콘텐츠를 전송하고, 수신료를 지불한 가입자만이 인증 과정을 거쳐 스크램블된 방송콘텐츠를 디스크램블하여 수신 할 수 있어야 한다. 일반적으로, 가입자 인증은 TV에 연결된 셋톱박스 (STB, Set-Top Box)와 스마트카드 기반으로 이루어지는데, 2004년 Jiang et al.이 관련 프로토콜을 제안하였고, 이 후에 여러 논문에서 보다 효율적인 프로토콜들이 제안되었다. 하지만, 이 프로토콜들은 모두 메모리와 계산 능력에 제한이 있는 스마트카드에 부담을 주는 모듈라 멱승 계산을 하도록 되어 있다. 본 논문에서는 해쉬함수와 exclusive-or 연산만을 이용한 효율적인 셋톱박스와 스마트 카드 간의 인증 및 키 교환 프로토콜을 제안하고, 제안하는 프로토콜이 다양한 공격에 안전함을 보인다.

• International Journal of Internet, Broadcasting and Communication
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• 제10권1호
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• pp.11-15
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• 2018

The application of Wireless Sensor Networks requires a wise utilization of limited energy resources. Therefore, a wide range of routing protocols with a motivation to prolong the lifetime of a network has been proposed in recent years. Hierarchical clustering based protocols have become an object of a large number of studies that aim to efficiently utilize the limited energy of network components. In this paper, the effect of mismatch in parameter estimation is discussed to evaluate the robustness of a distanced based algorithm called distributed clustering protocol in homogeneous and heterogeneous environment. For quantitative analysis, performance simulations for this protocol are carried out in terms of the network lifetime which is the main criteria of efficiency for the energy limited system.

• International Journal of Internet, Broadcasting and Communication
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• 제8권1호
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• pp.53-63
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• 2016

This paper applies WiMedia UWB network into a wireless ship area network (WSAN) so as to support high-quality multimedia services on board and reliable instrument control information as well, since the need for mixed high-quality video traffic and shipboard control data traffic is essential for a high-cost valued digital ship. Thus, in this paper, prioritized contention access (PCA) and distributed reservation protocol (DRP) based on WiMedia UWB (ECMA-368) MAC protocols are combined and proposed to such mixed traffic environment, by varying the portions of superframe according to traffic type. It is shown that the proposed WiMedia UWB MAC protocol can provide reliable mixed video and shipboard control data traffic as well.

• International Journal of Internet, Broadcasting and Communication
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• 제7권1호
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• pp.62-65
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• 2015

Wireless Sensor Network consists of several sensor nodes, these nodes loss some of their energy after the process of communication. So an energy efficient approach is required to improve the life of the network. In case of broadcast network, LEACH protocol uses an aggregative approach by creating cluster of nodes. Now the major concern is to built such clusters over WSN in an optimized way. This work presents the improvement over LEACH protocol. Hence we have different work environments where the network is having different capacities. The proposed work shows how the life time of the network will improve when the number of nodes varies within the network.

• International Journal of Internet, Broadcasting and Communication
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• 제11권1호
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• pp.17-26
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• 2019

The Constrained Application Protocol (CoAP) is a specialized web transfer protocol proposed by the IETF for use in IoT environments. CoAP was designed as a lightweight machine-to-machine protocol for resource constrained environments. Due to the strength of low overhead, the number of CoAP devices is expected to rise rapidly. When CoAP runs over UDP for wireless sensor networks, CoAP needs to support congestion control mechanisms. Since the default CoAP defines a minimal mechanism for congestion control, several schemes to improve the mechanism have been proposed. To keep CoAP lightweight, the majority of the schemes have been focused mainly on how to measure RTT accurately and how to set RTO adaptively according to network conditions, but other approaches such as rate-based congestion control were proposed more recently. In this paper, we survey the literature on congestion control for CoAP and discuss the future research directions.

• 한국통신학회논문지
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• 제22권11호
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• pp.2409-2424
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• 1997

Multicasting to mobile hosts(MHs) based on broadeasting results in overloaded unnecessary messages in case of th number of recipient MHs is relatively small compared with that of nodes in a network. In this paper we propose an improved multicast protocol in which messages are selectively flooded only to the (radio) cells within some distance from the cells where destination MHs reside most recently, so that the number of unnecessary messages carried in broadcasting is reduced. Detailed procedures for the protocol are provided and protocol properties are proven.

• 방송공학회논문지
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• 제17권4호
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• pp.596-610
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• 2012

본 논문은 모바일 방송망에서 고화질의 3D 방송 서비스를 제공하는 방법을 제안한다. 제안방법에서는 제한된 방송망의 대역폭을 극복하는 방법으로 오디오와 비디오를 방송망과 이동통신망으로 구성된 이종망을 통해 전달한다. 특히 서로 다른 망을 통해 각각 전송되는 스테레오스코픽 좌/우 영상을 동기화하는 방법을 제안한다. 본 논문에서의 동기화 방법은 RTP(Real Time Protocol)의 초기 타임스탬프(Timestamp)로부터의 옵셋을 이용하여 영상의 프레임(Frame) 순서를 구별하고 동일한 시점에 재생되어야 하는 좌/우 영상의 쌍을 찾는다. 마지막으로 3D 방송 서비스를 구별하고 타임스탬프를 얻기 위한 시그널링(Signaling)방법을 제시한다.

• 한국인터넷방송통신학회논문지
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• 제8권5호
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• pp.113-119
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• 2008

기존의 1-1-1 협력 프로토콜은 멀티 홉이 가지고 있는 경로손실감소 이득과 함께 MIMO와 동일한 공간 다이버시티를 제공한다. 이를 통해 싱글 홈, 멀티 홉보다 뛰어난 정보의 신뢰도 및 에너지 소비 감소를 얻을 수 있다. 하지만 기존의 1-1-1 협력 프로토콜은 단일의 협력 중계기를 사용하므로 경로손실감소 이득과 다이버시티 이득 계수가 2로 제한되어 있다. 따라서 본 논문에서는 두개의 협력 중계기 R1, R2를 사용한 1-2-1 협력 프로토콜을 제안한다. 1-2-1 협력 프로토콜은 경로손실감소 이득을 높이고 계수가 3인 다이버시티 이득을 얻는다. 또한, 협력 중계가 R2에서도 계수가 2인 다이버시티 이득을 얻을 수 있다. 협력 중계기는 DF (Decode and Forward)와 DR (Decode and Reencode) 방식을 사용하여 1-2-1 DF 또는 DR 협력 프로토콜을 형성하고, 클러스터링 기반의 무선 센서 네트워크 (WSNs)에 적용한다. 제안한 프로토콜의 성능평가를 위해 레일리 페이딩과 AWGN (Additive White Gaussian Noise) 채널이 합해진 채널에서 모의실험을 한다.

• 한국통신학회논문지
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• 제36권6B호
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• pp.631-641
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• 2011

Digital Multimedia Broadcasting (DMB) and Internet Protocol Television (IPTV) are now in commercial service, tearing down the traditional boundaries between the telecommunications and broadcasting sectors. These latest developments also hold important implications for research projects in related areas. Both telecommunications and broadcasting being fields with a strong service orientation, market demand should be the primary consideration when selecting research and development (R&D) projects in these areas. This study presents a process for selecting converged telecommunications-broadcasting technology development projects from a demand-oriented perspective, using criteria that are based on projected future demand characteristics. Aimed at increasing the efficiency of the R&D project selection process in telecommunications and broadcasting convergence, this study can point out new directions in R&D management in this field.

• International Journal of Internet, Broadcasting and Communication
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• 제9권4호
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• pp.38-43
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• 2017

Sensor Networks (WSNs) can be defined as a self-configured and infrastructure-less wireless networks to monitor physical or environmental conditions, such as temperature, sound, vibration, pressure, motion or pollutants and to cooperatively pass their data through the network to a main location or base-station where the data can be observed and analyzed. Typically a wireless sensor network contains hundreds of thousands of sensor nodes. The sensor nodes can communicate among themselves using radio signals. A wireless sensor node is equipped with sensing and computing devices, radio transceivers and power components. The individual nodes in a wireless sensor network (WSN) are inherently resource constrained: they have limited processing speed, storage capacity, communication bandwidth and limited-battery power. At present time, most of the research on WSNs has concentrated on the design of energy- and computationally efficient algorithms and protocols In order to extend the network life-time, in this paper we are looking into a routing protocol, especially LEACH and LEACH-related protocol. LEACH protocol is a representative routing protocol and improves overall network energy efficiency by allowing all nodes to be selected to the cluster head evenly once in a periodic manner. In LEACH, in case of movement of sensor nodes, there is a problem that the data transmission success rate decreases. In order to overcome LEACH's nodes movements, LEACH-Mobile protocol had proposed. But energy consumption increased because it consumes more energy to recognize which nodes moves and re-transfer data. In this paper we propose the new routing protocol considering nodes' mobility. In order to simulate the proposed protocol, we make a scenario, nodes' movements randomly and compared with the LEACH-Mobile protocol.