基于自适应节的多媒体流QoS保证的研究

分布式多媒体计算机系统的一个关键问题是保证连续多媒体流的服务质量（QoS)，大多数多媒体流要求的QoS是在一定范围内，即QoSmin,QoSmax]。为了保证QoS，计算机系统和网络系统必须分配足够的CPU、I/O、内存和网络带宽资源。在多媒体流传输过程中，这些资源的可利用率是动态变化的，尤其是带宽资源，如Internet，文中提出了自适应节的概念，采用PID调节技术，在QoSmin,QoSmax]内，动态调节QoS，自适应动态的可利用资源变化，既保证了多媒体流的QoS，又提高了资源的利用率。

The Guarantees of QoS for Multimedia Streams Based on Adaptive Session

The guarantees of quality of service (QoS) is a key issue for continue multimedia streams in distributed multimedia computer systems. The QoS required by most multimedia streams is in a set or range, QoS min , QoS max ]. For example, when video streams are transmitted on network in a video conference system, theimage frame rate of QoS can be set 15 frame/second, 25 frame/second]. Computer systems and network systems must allocate enough resources such as CPU, I/O, memory and bandwidth to guarantee the QoS. These resources are dynamic variations in availability e.g. bandwidth in Internet during multimedia streams transmission. In detail, the CPU, I/O and memory resources in computer systems are dynamic variations in availability with the number of processes and threads and the bandwidths in network systems are dynamic variations in availability with the amount of communications among nodes. The adaptive session is defined in this paper. It can dynamic adjust its QoS in QoS min , QoS max ] by PID to adapt the variations in resource availability. It can adapt QoS higher or better when there are more available resources in systems, and it can adapt QoS lower or worse when there are little available resources. Thus, it not only meets the QoS required bout also improves the useful of resources.