• The KIPS Transactions:PartC
• /
• v.15C no.6
• /
• pp.557-566
• /
• 2008

NGN(Next Generation Network) is a communication network which can make use of broadband and QoS-enabled transport technologies. One of the main service issues over NGN is a multimedia service, such as IPTV, using a multicast method. And overlay multicast technology is one of the promising solutions instead of traditional multicast technology which has a few problems, and supports flexibility and scalability for multicast services. Also, the main controversial topic in NGN and overlay multicast is QoS. In the present paper, we designed an agent in each receiver's network, and a manager which is in a source network and which manages the whole multicast network. Both of them are communicating with each other and applying resource policies to their multicast network. This mechanism enables overlay multicast to support QoS, focusing on RACF(Resource and Admission Control Functions) in NGN QoS architecture.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2009.10a
• /
• pp.780-783
• /
• 2009

The application of MOST150 technology has been required to satisfy the demand for the automotive infotainment system and the higher bandwidth requirements caused by the increase of the multimedia processing capacity. The Ethernet technology applied gateway was implemented for an efficient transmission of multimedia, a vehicle diagnosis, an external communication, a data processing between the MOST150 and the CAN communication method applied to many existing vehicles. The new algorithm and application were suggested in order to efficiently perform the data processing between other types of communication systems. The existing MOST150 frame is mainly composed of the Control Channel, the Legacy Packet Channel(async) and the Synchronous /Isochronous Channels and performs the data processing through these sequential channels. With the sense of this process, this study suggested the new algorithm that the Mapping method of the IETF's QoS Management was applied to the MOST150 technology for the efficient QoS.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.11 no.8
• /
• pp.1582-1588
• /
• 2007

According to recently presented QoS architecture by 3GPP, a traffic conditioner may be deployed to provide conformance of the negotiated QoS. In this paper, a real-time frame-layer rate control method which can be applied to the traffic conditioner of 3GPP is proposed. The proposed rate control method uses an efficient frame skipping algorithm method for low computational complexity, and performs bit allocation at the frame level to minimize the average distortion over an entire sequence as well as variations in distortion between frames. The proposed algorithm does not produce time delay from encoding, and is suitable for real-time low-complexity video encoder.

• Proceedings of the IEEK Conference
• /
• 2002.06c
• /
• pp.177-180
• /
• 2002

This paper introduces a new distributed QoS (Quality of Service) control system for clusters of web servers. The proposed system can employ not only network bandwidth but also other metrics such as processor load, memory usage, and storage access load that affect the overall system performance. Moreover, it controls over clustered\ulcorner workstations in of-der to utilize idle resources among workstations. This architecture maximizes overall usage of cluster of web servers while it provides predictable and differentiated performance for each contents volume. We implemented a prototype of introduced system, and the test results showed the proposed method can control QoS in a cluster server system.

• The KIPS Transactions:PartC
• /
• v.8C no.1
• /
• pp.60-67
• /
• 2001

Multicast Protocol for multimedia service on the Internet can be classified into two types, e.g., source based tree and shared tree according to difference of tree construction method. Shared tree based multicast is known to show outstanding results in the aspect of scalability than source based tree. Generally, There have been lots of researches on the method to satisfy QoS constraints through proper Rendezvous Point (RP) in the shared tree. In addition, as the multicast group members join and leave dynamically in the service time, RP of the shared tree should b be reselected for guranteeing Qos to new member, But, RP reselection method has not been considered generally as the solution to satisfy QoS C constraints. In this paper, new initial RP selection and RP reselection method are proposed, which utilize RTCP (Real Time Control Protocol) report packet fields. Proposed initial RP selection and RP reselection method use RTCP protocol which underlying multimedia application service So, the proposed method does not need any special process for collecting network information to calculate RP. New initial RP selection method s shows better performance than random and topology based one by 40-50% in simulation. Also, RP reselection method improves delay p performance by 50% after initial RP selection according to the member’s dynamicity.

• Proceedings of the IEEK Conference
• /
• 2004.06a
• /
• pp.107-110
• /
• 2004

IEEE 802.15.3 is wireless Medium Access Control(MAC) and Physical Layer(PHY) specification for high rate WPAN (Wireless Personal Area Network). IEEE 802.15.3 MAC Layer provides Qos with three kinds of acknowledgements; No acknowledgement, Immediate acknowledgement, and Delayed acknowledgement. This paper presents how to improve QoS with new acknowledgement method called Delayed Negative acknowledgement. This paper describes the method of using Delayed Negative acknowledgement and presents the calculation of QoS improvement by using Delayed Negative acknowledgement.

• Journal of KIISE:Computer Systems and Theory
• /
• v.26 no.1
• /
• pp.98-106
• /
• 1999

본 논문에서는 대용량 입출력을 수행하는 태스크의 QoS를 제어하기 위한 방법으로사용자가 시스템에 입출력 요구시 요구 대역폭을 제시하고, 파일시스템에서 디스크개소와 입출력 이벤트를 고려하여 입출력의 병렬성을 제어함으로써 QoS를 제어하는 방법을 제안하였다. 그리고, 시스템에서 각 태스크가 주어진 병렬성을 가지고 입출력을 진행하고 있을 때, 요구 대역폭을 가지고 입출력을 요구하는 태스크의 대역폭을 만족시키기 위한 병렬성을 계산하는 분석 모델을 유도하였다. 그리고, 디스크 입출력의 병렬성을 이용하여 대용량 입출력의 QoS를 효율적으로 제어할 수 있음을 분석 모델의 결과를 통해 검증하였다.

• KIPS Transactions on Computer and Communication Systems
• /
• v.2 no.7
• /
• pp.283-292
• /
• 2013

In order to ensure high performance, all the servers in an existing server cluster are always On regardless of number of real-time requests. They ensure QoS, but waste server power if some of them are idle. To save energy consumed by servers, the server power mode control was developed by shutdowning a server when a server is not needed. There are two types of server power mode control depending on when a server is actually turned off if the server is selected to be off: static or dynamic. In a static mode, the server power is actually turned off after a fixed time delay from the time of the server selection. In a dynamic mode, server power is actually turned off if all the services served in the server are done. This corresponds to a turn off after a variable time delay. The static mdoe has disadvantages. It takes much time to find an optimal shutdown time manually through repeated experiments. In this paper, we propose a dynamic shutdown method to overcome the disadvantages of static shutdown. The proposed method allows to guarantee user QoS with good power-saving because it automatically approaches an optimal shutdown time. We performed experiments using 30 PCs cluster. Experimental results show that the proposed dynamic shutdown method is almost same as the best static shutdown in terms of power saving, but better than the best static shutdown in terms of QoS.

• Journal of Institute of Control, Robotics and Systems
• /
• v.8 no.4
• /
• pp.303-307
• /
• 2002

Virtual hosting is a typical service to connect each directory of site and domain name. If traffic amounts may increase at one site present in the server, then it affects traffic amounts of other sites as well (including the sites which have flew requests). To overcome this problem, we suggest a simple feedback-control concept for the system by periodically monitoring the traffic and properly actuating traffic dispersions by investigating the log file. Specifically, large files are to be served in a backup server (to reduce the workload of the main server) by changing their own URL's in html format. In other words, it automatically redistributes the workload by using the URL. Furthermore, we also use the redirecting method by just adding html tags to html header. This method efficiently handles the workload and maintains the capability of the server effectively to the varying workload.

• Journal of KIISE:Computing Practices and Letters
• /
• v.10 no.6
• /
• pp.435-447
• /
• 2004

For VOD systems, it is important to provide QoS to more users under the limited resources. To analyze QoS issues in real environment, we implement clustered VOD server and embedded client system based on the Linux open source platform. The parallel processing of MPEG data, load balancing for nodes and VCR like functions are implemented in the server side. To provide more user friendly interface, the general TV is used for a VOD client's terminal and the embedded board is used supporting for VCR functions. In this paper, we measure the performance of the implemented VOD system under the various user requirement features and evaluate the sources of performance limitations. From these analyses, we propose the dynamic admission control method based on the availability memory and network bandwidth. The proposed method enhances the utilization of the system resource for the more QoS media streams.