The QoS-guaranteed real-time communication for multimedia applications becomes significantly more important and popular, and these applications require high bandwidth requirements and soft real-time constraint. But, they impose other requirements which are peculiar to multimedia traffic, for example, bounded delay, bounded jitter, bounded packet loss, and bounded synchronization gap. And these requirements are defined as QoS(Quality of Service) of the application. To support QoS from system and network components, it will require accurate traffic modeling, which is infeasible because we can not make good model to reflect the characteristics of every application's traffic in the world. It is common approach to delegate the duty of QoS specification to the application which actually wants to communicate.
The QoS needed for applications are down translated to the QoS parameters of operating system and network subsystems. And the arising problem is how to support application QoS from system/network components. We thought that operating system and transport/network system should take the reservation(to achieve minimum QoS requirements of and application) and scheduling techniques(to achieve best effort enhancement of QoS requirements of the application) at the same time for system and network resources to guarantee application user level QoS requirements. The multimedia data's characteristics and QoS parameters diverse widely according to applications and coding schemes. In addition, they are also diverse with sub-media or substream(which we define it as parts of media, for example, subblock or subband of video/audio signal). And if we can support application QoS with further specified substream level QoS, we can achieve more efficient QoS management.
So, We propose the new QoS parameter which is based on human visual system's temporal and spatial characteristics (i.e. spatial texture and temporal motion tradeoff, and adaptation to motion acceleration) to fit perceptually for application user's QoS requirement (i.e. bound of end-to-end jitter of each stream needed for transmission of subband video coded data). And, we also propose QoS scheduling scheme which maximizes our QoS measure, and show that our QoS management scheme is superior to other real-time multimedia scheduling algorithms by simulation.
멀티미디어 응용프로그램들이 점점 보편화 되고 있음에 따라 멀티미디어 응용 프로그램들이 요구하는 QoS수준을 제공하기위한 통합된 QoS 관리기법이 사용될 필요가 있다. 멀티미디어 응용은 실행시간을 어길 경우 실행의 값어치가 시간의 함수값에 따라 떨어지는 연실시간 시스템이다. 기존의 멀티미디어 응용프로그램은 지연시간, 지연시간 변이, 패킷 상실률 등에서 일정한 기준치이상의 QoS를 시스템레벨에서 제공하기를 요구하고,시스템은 이러한 QoS기준을 만족시키기위해 자원예약이나,자원 스케쥴링을 통해 자원을 관리하였다. 본 논문에서는 비디오에 대한 사람의 인지시각 특성을 이용하여 자원관리를 함으로써 사용자가 보기에 좀 더 좋은 비디오 질을 유지할 수 있는 자원관리기법에 대한 연구를 하였다. 본 연구를 통해 제안된 새로운 QoS 척도와 스케쥴링기법은 시뮬레이션을 통해 기존의 연구와 비교해 본 결과 사람의 인지 성능에서 보다 나은 결과를 보여주고 있다.
