• Journal of Korea Multimedia Society
• /
• v.7 no.1
• /
• pp.54-63
• /
• 2004

This paper describes a hybrid QoS guarantee scheme for high quality audio streaming services on the Internet. The continuous playback of the audio data requires the isochronous transmission of the audio data packet through the Internet. In order to retain the QoS at the ultimate destination (client) as the same as servers provide, the transmission protocols should consider the error conditions such as packet loss, and out of order delivery. Generally, the protocols supporting the transmission of continuous media data do not try to recover the errors. The protocols are working somehow for the toll quality multimedia streaming services, but rot for the high quality streaming services, such as the DVD sound/music payback. The hybrid QoS guarantee scheme includes the three mechanisms to overcome the problem. The selective retransmission for the lost packet, the adaptive buffering at client-side, and the adaptive transmission rate at server-side are totally adopted to recover the packet loss with the minimal overhead, to prevent from the buffer starvation during the retransmission, and to maintain the isochronous transmission even after the retransmission. The experiments have shown good results for the high Quality audio streaming services on the Internet.

• Proceedings of the Korea Multimedia Society Conference
• /
• 2001.11a
• /
• pp.12-17
• /
• 2001

본 논문에서는 낮은 대역폭의 무선 네트워크상에서 MPEG 스트리밍을 위한 방법으로, DCT 계수의 제거에 기반한 QoS 필터링 방법과 매크로 블록상의 움직임 벡터와 인트라 블록의 비율을 고려한 영상분식을 통하여 분석된 내용에 가장 알맞는 필터의 선택과 필터의 적용 수준을 네트워크의 상태에 따라 결정하여 대역폭을 만족시킬 수 있는 비트레이트의 조절로서 원활한 스트리밍을 가능하게 하며 영상분석을 통하여 영상의 품질을 높여 고품질의 영상 멀티미디어 서비스와 최소한의 부하를 줄 수 있는 설계로서 서버운용시 과효율을 놀일 수 있도록 한다.

• Proceedings of the Korea Multimedia Society Conference
• /
• 1998.04a
• /
• pp.328-332
• /
• 1998

인간의 정보전달 방식이 텍스트와 같은 단일 미디어 중심에서 텍스트, 이미지, 음성, 영상 등의 멀티미디어 중심으로 바뀌어 감에 따라 멀티미디어 응용에 대한 관심이 고조되고 있다. 그러나, 멀티미디어 응용의 대표적 갈래인 VOD(Video On Demand) 시스템은 그 특성 및 구조에 대해 축적된 연구가 많은 반면, NOD(News On Demand) 시스템은 그 연구가 거의 없는 실정이다. 이 점에 착안하여 본 논문에서는 NOD 데이터 및 시스템의 특성을 우선적으로 살펴보고, 아울러 NOD 시스템 전체에 대한 구조를 제시함으로써 NOD 시스템에 대한 이해를 돕고자 한다. 뿐만 아니라, 차등적인 QoS를 제공함으로써 여러 가지 비정상적인 상황에 대처하는 서버의 능력을 높이고자 한다.

• Proceedings of the Korea Multimedia Society Conference
• /
• 2003.11b
• /
• pp.770-773
• /
• 2003

본 논문에서는 차세대 인터넷으로 진화함에 있어 새로운 핵심 기술로 평가 받고 있는 MPLS 네트워크에서 VoIP 서비스 제공을 위하여, DiffServ 모델을 지원하는 MPLS 네트워크를 NS-2로 구성하였다. 여기에 VoIP 트래픽이 혼잡할 때에도 전송 품질을 보장 받을 수 있는 DiffServ 모델을 지원하는 QoS 모듈을 제안하였다. 이를 이용하여 VoIP 트래픽이 혼잡할 때에도 요구되는 전송 품질을 보장 받을 수 있음을 시뮬레이션을 통해 확인했다.

• Journal of the Korea Society for Simulation
• /
• v.19 no.4
• /
• pp.89-98
• /
• 2010

In the heterogeneous system of various wired or wireless network with IP-based backbone, the continuities of agreedon QoS for multimedia services should be guaranteed regardless of network types and terminal mobility through seamless vertical handover. This paper proposes a QoS provisioning mechanism called D-ISHO which guarantees the continuities of agreed-on QoS and seamless for multimedia services by considering both such characteristics as delay, loss rate and jitter per each service and such status as available band-width, call arrival rate and data transmission rate during the vertical handover. Simulation is done for performance analysis with the measure of handover failure rate and packet loss rate.

• The KIPS Transactions:PartC
• /
• v.9C no.5
• /
• pp.699-708
• /
• 2002

Since various terminals and different networks get involved in playing of a multimedia presentation, the case that the presentation QoS at a destination should be different from the QoS of multimedia data at a source occurs frequently. For playing the multimedia presentation, the multimedia data at a source should be transcoded into the multimedia data satisfying the QoS required at the terminal. The problem of generating the transcoding path is that, for a given multimedia presentation, different transcoding paths depending the terminal and networks should be generated. That is, a fixed transcoding path cannot be applied to a multimedia presentation. Instead, whenever the terminal and network to play the presentation get determined, a proper transcoding path should be regenerated automatically. In this paper, the algorithm for generating the transcoding path and the method for checking the playability of the generated path are proposed. The generating algorithm adopted the technique of Context Free Grammar in describing the set of transcoding resources and a user's transcoding rules in order to utilize the well-known compiler techniques. For the playability check, a method of computing the transcoding time and the delay time between data units are proposed. Finally all the proposed methods were implemented in the stream engine, called Transcore and the presentation-authoring tool, called VIP, we had developed. And the test results with a sample scenario were presented at the last.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.29 no.9A
• /
• pp.1031-1038
• /
• 2004

The call admission control algorithm of hybrid scheme is proposed to enhance the QoS(quality of service) of attempted multimedia calls. In the initial stage of 3rd generation multimedia services networks, the major limitations include the small sefyice coverage and the limited radio link capacity. Because the initial massive deployment of network elements such as base stations, base station controllers, and mobile switching centers is restricted to populated areas and the other areas should be covered with the fewer network elements, the radio channel resources are hmited and coverage network is supposed to be established. Therefore the QoS of multimedia services is expected to be severely degraded when tentative traffic hot spot occurs frequently. Thus, the blocking probability of attempted calls mcreases when relatively large number of users try to place multimedia calls in a hot spot area of the wireless networks. In this situation, the proposed hybrid scheme can mitigate the degradation of the QoS of multimedia services by using the available radio channels of the neighboring cells.

• Convergence Security Journal
• /
• v.8 no.2
• /
• pp.41-50
• /
• 2008

Recently amount of traffic into the network rapidly increase since multimedia streaming services is generally adopted for application. In addition, various network management systems have been suggested for providing a stable service and QoS guarantee. It is necessary for such systems to have QoS monitoring module in order to evaluate acceptance or violation of QoS requirements by analogizing a state information of each node within network. In this paper, we suggest a network management system to evaluate QoS level between end-to-end agents and analysis traffics transmitted between them. The proposed system is implemented for the purpose of collecting network traffic information and monitoring of the view. The proposed system makes user easily understand information of QoS parameters such as throughput, delay and jitter by adopting a method of visual and numerical representation. To achieve this, we purportedly generate test packet into network for confirming acceptance or violation of QoS requirements from point of view of multimedia application service.

• Proceedings of the IEEK Conference
• /
• 2002.06a
• /
• pp.45-48
• /
• 2002

This paper presents a QoS-guaranteed traffic control system which supports QoS of realtime packet transmission for the multimedia communication. The traffic control system presented in this paper applies the integrated service model and provides QoS o(packet transmission by means of determining the packet transmission rate with the policy of network manager and the optimal resource allocation according to the end-to-end traffic load. It also provides QoS for the realtime packet transmission through the AWF2Q+ Scheduling algorithm and per-class queuing method.

• The KIPS Transactions:PartA
• /
• v.16A no.3
• /
• pp.181-188
• /
• 2009

Transcoding is one of core techniques that implement VoD services according to QoS. But it consumes a lot of CPU resource. A transcoding proxy transcodes multimedia objects to meet requirements of various mobile devices and caches them to reuse later. In this paper, we propose a service policy that reduces the load of transcoding multimedia objects by degrading QoS in a transcoding proxy. Due to the tradeoff between QoS and the load of a proxy system, a transcoding proxy provides lower QoS than a client's requirement so that it can accomodate more clients.