• The Transactions of the Korea Information Processing Society
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• v.7 no.2S
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• pp.577-593
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• 2000

A distributed video-on-demand (VoD) system is one where collection of video data is located at dispersed sites across a computer network. In a single site environment, a local video server retrieves video data from its local storage device. However, in the setting of a distributed VoD system, when a customer requests a movie from the local server, the server may need to interact with other servers located across the network. In this paper, we present three types of presentation plans that a local server must construct in order to satisfy the customer request. Informally speaking, a presentation plan is a temporally synchronized detailed sequence of steps that the local server must perform for presenting the requested movie to the customer. This involves obtaining commitments from other video servers, obtaining commitments from the network service provider, as well as making commitments of local resources, within the limitations of available bandwidth, available buffer, and customer data consumption rates. Furthermore, for evaluating the goodness of a presentation plan, we introduce two measures of optimality for presentation plans: minimizing wait time for a customer, and minimizing access bandwidth is used. We develop algorithms to compute optimal presentation plans for all three types, and carry out extensive experiments to compare their performance. We have also mathematically proved certain results for the presentation plans that had previously been verified experimentally in the literature.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.23 no.4
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• pp.821-835
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• 1998

The Digital Audio-Visual Council(DAVIC) that was established to develop useful multimedia communication services has completed the specifications for providing on-demand services such as Movie on Demand(MoD), Teleshopping and accepting Internet service. And then they are proceeding the works to suport converstional communcation services like Plain Old Telecphone Service(POTS), Video telephone, Video teleconferencing. In this paper, we prpose an efficient terminal architecture which can provide conversational multimedia communication services on DAVIC Set-Top Box (STB) environments. To apply the implemented conversational terminal to the multipoint communication environment, we considered the factors of Qurlity of Services(QoS) that determine grade of conversational communication service. We also present the inter-working scheme and that system structure to satisfy QoS by using new MPEG video bridge which gurantees end to end delay requirements as major element of QoS for achieving the real time communication and does not accompany visual quality degradation.

• The Transactions of the Korea Information Processing Society
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• v.4 no.10
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• pp.2581-2595
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• 1997

In this paper, the real-time facility of the operating system for a VOD(Video On Demand) server have been analyzed and implemented. The requirements of the real-time scheduling have been gathered by analyzing the model of the video-data-transfer-path. Particularly, the influence of the bottleneck subsystem have been analyzed. Thus, we have implemented the real-time scheduler and primitives which is proper for processing the digital video. In performance measurements, the degree of the guarantee of the real-time scheduler have been experimented. The measured data show that the most time constraints of the process is satisfied. But, the network protocol processing by the interrupt is a major obstacle of the real-time scheduling. We also have compared the difference between the real-time scheduler and the non-real-time scheduler by measuring the inter-execution time. According to the measured results, the real-time scheduler should be used for efficient video service because the processor time allocated to the process can't be estimated when the non-real-time scheduler is used.

• Proceedings of the IEEK Conference
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• 2000.11a
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• pp.453-456
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• 2000

This paper describes IMT-2000 Testbed System which consists of ATM based IMT-2000 exchange(A-lMX), RNC simulator, HLR simulator, SCP simulator, B-ISDN subscriber simulator and MS simulator. Simulators were developed to verify the mobile functions and basic services of IMT-2000 like Videophone, VoD(Video on Demand), and Internet access. UPT(Universal Personal Telecommunication) service could be adapted well to this testbed system. Until the entire network elements are developed fully, this testbed system can be used to prove new services in IMT-2000 network.

• 한국IT서비스학회:학술대회논문집
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• 2006.11a
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• pp.352-359
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• 2006

VoD 전송 방식을 설계할 때 가장 중요한 요소들에는 정해진 대역폭에서 사용자 대기시간 (Viewer's Waiting Time)과 클라이언트에서 요구하는 최대 버퍼 요구량(Max Client Buffer Requirement)을 줄이는 문제를 꼽을 수 있다. 점점 더 복잡해지는 VoD 전송 기술의 개발로 인해 사용자 대기시간과 최대 버퍼 요구량의 관점에서 성능 향상과 반비례하는 시스템 복잡도를 줄이는 문제 또한 VoD 전송 방식을 설계 시 고려 해야 할 중요 사항 중의 하나이다. 이 논문에서는 시스템 복잡도를 낮추면서 사용자 대기시간과 최대 버퍼 요구량의 성능을 동시에 향상시키기 위한 방법으로 기존의 VoD 전송 방식들 가운데 가장 간단한 모델과 최대 버퍼 요구량의 성능을 가장 향상시킨 모델의 결합으로 구현 가능한 Hybrid 방식을 제안하고 있다. 이 논문은 결과적으로 사용자 대기시간은 기존 Staircase Broadcasting방식과 Fast Broadcasting 방식과 비교했을 때 동일한 성능을 나타내고 있고 최대 버퍼 요구량은 유사성능을 나타냄을 알 수 있다. 이 논문에서 제안한 방식은 사용자 대기시간이 짧아야 하고 저장공간이 많이 요구되지 않으며 사용자의 요청이 갑자기 증가될 수 있는 hot 비디오에 적용이 가능하다. 또한 다양한 환경에 따라 Staggered Broadcasting 방식과 Staircase Broadcasting 방식의 채널 수를 적절히 조정함으로써 데이터 송수신 효율을 극대화 시킬 수 있다. 이 논문의 구성은 제시한 방법에 적용된 방식들과 비교대상이 되는 방식들에 대해 살펴보고 제시한 방식의 성능 모델을 이용한 실험을 통해 각종 VoD 전송 방식들과 비교 분석하는 과정으로 기술하였다.

• The Transactions of the Korea Information Processing Society
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• v.6 no.2
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• pp.385-395
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• 1999

Video-On-demand system provides electronic video rental services from remote video servers on a broadband communication networks. When we assume some situation that serve the same video stream by batching, each time single video stream became available at server-end side, we face the problem that what video stream to be scheduled at what time instant. Hence, in order to manage the resource bandwidth which is different at each stream, the policy of channel allocation became important factor. In this work, we proposed three type of scheduling policies with queueing, as are cumulative Waiting Time(CWT), Mean Waiting Time(MWT) and Predictable Popular Factor(PPF). While CWT policy is good for popular video, MWT policy was good for non-popular video. Also, we know that PPT policy has some fairness for average wait time and reneging rate of user requests.

• Journal of KIISE:Information Networking
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• v.32 no.1
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• pp.80-88
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• 2005

In ubiquitous spaces, a user wants to be provided with a VOD service while moving one space to another freely. Since the traditional VOD system is dependent on user location, the VOD server transmits video data to a single client during a session. If the user moves to another space, he/she should close the old session and make a new request for the same video. However, the location-aware VOD system supports user mobility by closing and opening the session automatically. That is, the VOD system automatically perceives the movement of a user and allows the server to change the data flow so that a client near the user can receive the video data. This paper proposes a location-aware VOD service architecture and a session handoff scheme to provide a mobile user with continuous video delivery and implements a location-aware VOD prototype system based on Jini and Java. In experiment, we show that the proposed handoff scheme has a smaller handoff delay than the other handoff scheme.

• Journal of Broadcast Engineering
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• v.24 no.7
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• pp.1209-1220
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• 2019

The demand for virtual reality (VR) is rapidly increasing. Providing the immersive experience requires much operation and many data to transmit. For example, a 360-degree video (360 video) with at least 4K resolution is needed to offer an immersive experience to users. Moreover, the MPEG-I group defined three degrees of freedom plus (3DoF+), and it requires the transmission of multiview 360 videos simultaneoulsy. This could be a burden for the VR streaming system. Accordingly, in this work, a bitrate-saving method using projection conversion is introduced, along with experimental results for streaming 3DoF+ 360 video. The results show that projection conversion of 360 video with 360lib shows a Bjontegaard delta bitrate gain of as much as 11.4%.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.1B
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• pp.101-110
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• 2011

With the deployment of broadband networking technology, many clients are enabled to receive various Video on Demand (VoD) services. To support many clients, the network should be designed by considering the following factors: viewer's waiting time, buffer requirement at each client, number of channel required for video delivery, and video segmentation complexity. Among the currently available VoD service approaches, the Polyharmonic and Staircase broadcasting approaches show best performance with respect to each viewer's waiting time and buffer requirement, respectively. However, these approaches have the problem of dividing a video into too many segments, which causes very many channels to be managed and used at a time. To overcome this problem, we propose Polyharmonic-Staircase-Staggered (PSS) broadcasting approach that uses the Polyharmonic and Staircase approaches for the head part transmission and the Staggered approach for the tail part transmission. It is simple and bandwidth efficient. The numerical results demonstrate that our approach shows viewer's waiting time is comparable to that in the Harmonic approach with a slight increase in the bandwidth requirement, and saves the buffer requirement by about 60\% compared to the Harmonic broadcasting approach by simply adjusting the video partitioning coefficient factor. More importantly, our approach shows the best performance in terms of the number of segments and the number of channels managed and used simultaneously, which is a critical factor in real operation of VoD services. Lastly, we present how to configure the system adaptively according to the video partitioning coefficient.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.1
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• pp.45-52
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• 2009

Currently broadcasting and telecommunication has integrated, And IPTV Service has appeared who called TPS(Triple Play Service) which integrated with broadcasting, telecommunication and Phone Service. IPTV provide broadcasting service and VOD(Video on Demand) service, and it must be satisfied digital content security. For this condition, IPTV Forum working on standardization of interface for digital content security. The Security solution for broadcasting and VOD are CAS (Conditional Access System) and DRM(Digital Rights Management). But these solutions manufactured by many vendors, so there is no inter-operability. And after finished standardization of interface for CAS and DRM system, the problem of inter-operability with them will be issued. For this reason, Rights management system which possible to operate independently with platform is necessary. In this paper, To protect multimedia digital content, we designed and implemented Conditional Access Management System.