• The Journal of the Korea Contents Association
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• v.18 no.3
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• pp.34-40
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• 2018

In this study, the optimal buffer size is calculated for seamless video playback on a mobile device. Buffer means the memory space for multimedia packet which arrives in mobile device for video play such as VOD service. If the buffer size is too large, latency time before video playback can be longer. However, if it is too short, playback service can be paused because of shortage of packets arrived. Hence, the optimal buffer size insures QoS of video playback on mobile devices. We model the process of buffering into a discret-time queueing model. Mean busy period length and mean waiting time of Geo/G/1 queue with N-policy is analyzed. After then, we uses the main performance measures to present numerical examples to decide the optimal buffer size on mobile devices. Our results enhance the user satisfaction by insuring the seamless playback and minimizing the initial delay time in VOD streaming process.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.9 no.6
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• pp.2144-2159
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• 2015

CISCO VNI predicted an average annual growth rate of 66% for mobile video traffic between 2014 and 2019 and accordingly much academic research related to video streaming has been initiated. In video streaming, Adaptive Bitrate (ABR) is a streaming technique in which a source video is stored on a server at variable encoding rates and each streaming user requests the most appropriate video encoding rate considering their channel capacity. However, these days, ABR related studies are only focusing on real-time rate adaptation omitting energy efficiency though it is one of the most important requirement for mobile devices, which may cause dissatisfaction for streaming users. In this paper, we propose an energy efficient prefetching based dynamic adaptive streaming technique by considering the limited characteristics of the batteries used in mobile devices, in order to reduce the energy waste and provide a similar level of service in terms of the average video rate compared to the latest ABR streaming technique which does not consider the energy consumption. The simulation results is showing that our proposed scheme saves 65~68% of energy at the average global mobile download speed compared to the latest high performance ABR algorithm while providing similar rate adaptation performance.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2009.01a
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• pp.13-16
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• 2009

Multi-view video broadcasting have been conducted with a variety of different system architectures. However, the previous systems have focused on wired broadcasting. On the contrary, our system is designed to be applied to mobile 3DTV broadcasting. We present a service framework adaptable to mobile clients where the load on the client is reduced as much as possible. MPEG-21 multiview DIA description schemes are presented for the efficient adaptation between the serer and client. Furthermore, we examine the feasibility of the proposed framework by analyzing the frame rate that a client device can process.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.9 no.9
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• pp.3635-3654
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• 2015

With the rapid development of smart devices and mobile Internet, the video application plays an increasingly important role on mobile devices. Understanding user behavior patterns is critical for optimized operation of mobile live streaming systems. On the other hand, volume based billing models on cloud services make it easier for video service providers to scale their services as well as to reduce the waste from oversized service capacities. In this paper, the watching behaviors of a commercial mobile live streaming system are studied in a content-centric manner. Our analysis captures the intrinsic correlation existing between popularity and watching intensity of programs due to the synchronized watching behaviors with program schedule. The watching pattern is further used to estimate traffic volume generated by the program, which is useful on data volume capacity reservation and billing strategy selection in cloud services. The traffic range of programs is estimated based on a naive popularity prediction. In cross validation, the traffic ranges of around 94% of programs are successfully estimated. In high popularity programs (>20000 viewers), the overestimated traffic is less than 15% of real happened traffic when using upper bound to estimate program traffic.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.11 no.1
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• pp.159-163
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• 2011

3-Screen service means that one video contents is operated on 3 different terminals(smart-phone, IP-TV, internet PC) with same service browser. In this paper, we developed 3-Screen video service system based on imbedded web browser. We evaluated and analysed of developed 3-Screen service system through Agribusiness video service offering test environment on the LG U+ network. As a result of tests, it showed that 3-Screen video service was well performed in each 3-Screen service terminals. The result of this paper will be utilized in various application developments for the 3-Screen video service in the future.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.4 no.6
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• pp.1152-1168
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• 2010

Recently, due to the prevalence of various mobile devices and wireless broadband networks, there has been a significant increase in interest and demand for multimedia streaming services such as the mobile IPTV. In such a wireless broadband network, transmitting a continuous stream of multimedia data is difficult to achieve due to mobile stations (MSs) movement. Providing Quality of Service (QoS) for multimedia video streaming applications requires the server and/or client to be network-aware and adaptive. Therefore, in order to deploy a mobile IPTV service in wireless broadband networks, offering users efficient wireless resource utilization and seamlessly offering user perceived QoS are important issues. In this paper, we propose a new adaptive streaming scheme, called MARC (Mobile-aware Adaptive Rate Control), which adjusts the quality of bit-stream and transmission rate of video streaming based on the wireless channel status and network status. The proposed scheme can control the rate of multimedia streaming to be suitable for the wireless channel status by using awareness information of the wireless channel quality and the mobile station location. The proposed scheme can provide a seamless multimedia playback service in wireless broadband networks in addition to improving the QoS of multimedia streaming services. The proposed MARC scheme alleviates the discontinuity of multimedia playback and allocates a suitable client buffer to the wireless broadband network. The simulation results demonstrate the effectiveness of our proposed scheme.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.6 no.3
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• pp.919-940
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• 2012

Video on Demand (VOD) is a multimedia service which allows a remote user to select and then view video at his convenience at any time he wants, which makes the VOD become an important technology for many applications. Numerous periodic VOD broadcasting protocols have been proposed to support a large number of receivers. Broadcasting is an efficient transmission scheme to provide on-demand service for very popular movies. This paper proposes a new broadcasting scheme called Popularity Cushion Staggered Broadcasting (PCSB). The proposed scheme improves the Periodic Broadcasting (PB) protocols in the latest mobile VOD system, which is called MobiVoD system. It also, reduces the maximum waiting time of the mobile node, by partitioning the $1^{st}$ segment of the whole video and storing it in the Local Media Forwarder (LMF) exactly in the Pool of RAM (PoR), and then transmitting them when the mobile nodes miss the $1^{st}$ broadcasted segment. The results show that the PCSB is more efficient and better than the all types of broadcasting and caching techniques in the MobiVoD system. Furthermore, these results exhibits that system performance is stable under high dynamics of the system and the viewer's waiting time are less than the previous system.

• Journal of the Korea Society of Computer and Information
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• v.21 no.1
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• pp.49-57
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• 2016

In this paper we propose the resource allocation scheme for the overlaid macro-femtocell networks, which considers the type of handovers such as the inter-macrocell, macrocell-to-femtocell, femtocell-to-macrocell, or inter-femtocell in order to guarantee Quality of Service (QoS) and expand the accommodation capacity. Our proposed scheme takes into account the movement of mobile terminals, the QoS degradation, or the load control which trigger handovers in the overlaid networks, before it allocates resources dynamically. Moreover it considers QoS requirements of realtime or non-realtime mobile multimedia services such as video communication, Video on Demand (VoD) and dataa services. Simulation results show that our scheme provides better performances than the conventional one with respect to the outage probability, data transmission throughput and handover failure rate.

• Journal of Broadcast Engineering
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• v.17 no.4
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• pp.596-610
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• 2012

This paper proposes a method to provide the high quality 3D broadcasting service in a mobile broadcasting system. In this method, audio and video data are delivered through a heterogeneous network, consisting of a mobile network as well as a broadcasting network, due to the limited bandwidth of the broadcasting system. However, it is more difficult to synchronize the left and right video frames of a 3D stereoscopic service, which come through different types of networks. The proposed method suggests the use of the offset from the initial timestamp of RTP (Real Time Protocol) to determine the order of frames and to find the pair of a left and a right frame that must be played at the same time. Additionally, a new signaling method is introduced for a mobile device to request a 3D service and to get the initial RTP timestamp.

• Journal of Korea Multimedia Society
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• v.15 no.6
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• pp.814-826
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• 2012

In this paper, we propose scheduling algorithms for transporting variable-bit-rate video stream using playback buffer level of the clients over wireless communication networks. The proposed algorithms attempt to maximize the utilization of limited bandwidth between the central video server and the clients over a mobile network. Since a video server may serve several video request at the same time, it is important to allocate and utilize network bandwidth to serve them fairly and efficiently. In order to improve the quality of service and real-time performance of individual video playback, the video server attempts to allocate temporarily more network bandwidth to serve a video request with the lower buffer level preferentially. The simulation results prove the fair service and load balancing among the mobile concurrent clients with different buffer levels and hence maximizing the number of frames that are transported successfully to the client prior to their playback times.