无线环境下具有实时约束的主动队列管理机制

实时流业务的超期丢包率是衡量无线网络传输过程服务质量的常用参数，但是该参数并不能反映出具有不同重要度的数据包对视频质量的影响。该文将实时传输流的数据包重要度与超期丢包率结合，提出加权超期丢包率的概念，更加准确地描述丢包与视频质量的关系，在无线环境下提出基于数据包不同重要度的适用于实时约束流的主动队列管理算法，通过主动丢弃数据包以最小化服务过程中实时流的加权超期丢包率。仿真结果表明，相比于传统的队列管理算法和实时视频流滤波器算法，该超期数据包主动丢弃算法能够有效降低加权超期丢包率，提供更好的服务质量，提高大约0.5~1.5 dB的峰值信噪比(PSNR)增益。

Deadline-constrained Active Queue Management Mechanism in Wireless Networks

The expired-time packet loss rate is a common parameter to measure the quality of service of transmission of deadline-constrained traffic in wireless networks. However, this parameter can not reflect the influence on the quality of service of video caused by the packets with different levels of importance. In this paper, the definition of the weighted expired-time packet loss rate is first introduced with the consideration of the importance of different kinds of packets, which describes the connection between the packet loss and quality of video more specifically. Based on the definition, an active queue management mechanism is proposed, which can be applied to deadline-constrained transmissions in wireless networks, and this mechanism, considering different levels of importance of video packets, drop packets actively to minimize the weighted expired-time packet loss rate during the service. Simulation results show that compared with the traditional queue management mechanism and real-time video filtering mechanism, the active packet discard mechanism can effectively reduce the weighted expired-time packet loss rate and improve the quality of service of video to about 0.5~1.5 dB Peak Signal to Noise Ratio (PSNR) gain.