The Design of VoIP Systems with High Perceptual Conversational Quality

标题：高感知通话质量VoIP系统的设计PI：Benjamin W.Wah摘要本研究旨在设计实时的双方和多方VoIP(Voice-Over-IP)系统，当交互对话被人感知时，能够获得高质量的语音。它侧重于对会话质量的基本理解及其在以下策略中的权衡：调度接收的语音帧的回放、隐藏网络中丢失的帧、使用覆盖网络来路由携带语音帧的分组以及在多方对话中接纳新连接。网络连接上的对话的感知质量取决于单向只听的语音质量和从说话者的嘴到听者的耳朵所产生的嘴到耳的延迟。当存在网络延迟时，收听者感知到的对话由语音片段组成，这些语音片段由交替的短和长静默时段隔开。这种不对称性导致多方VoIP的感知质量较低，因为一些发言者似乎比其他人更远，而一些人的反应比其他人慢。在这项研究中，我们开发了一种统计方法来收集主观测试结果，并开发了一种分类方法来自动学习并将结果推广到看不见的网络和会话条件。我们研究了网络控制和调度算法来改善静默期的不对称性和接收到的语音段的质量。

Title: The Design of VoIP Systems with High Perceptual Conversational Quality PI: Benjamin W. WahAbstractThis research is on the design of real-time two-party and multi-party VoIP (voice-over-IP) systems that can achieve high quality when the interactive conversation is perceived by human listeners. It focuses on the fundamental understanding of conversational quality and its trade-offs in strategies for scheduling the playback of speech frames received, concealing frames lost in the network, routing packets that carry speech frames using an overlay network, and admitting new connections in multi-party conversations. The perceptual quality of a conversation over a network connection depends on the one-way listening-only speech quality and the mouth-to-ear delay incurred from the mouth of a speaker to the ear of a listener. When there are network delays, a conversation perceived by a listener consists of speech segments that are separated by alternating short and long silence periods. This asymmetry leads to low perceptual quality in multi-party VoIP because some speakers appear to be more distant than others, whereas some respond slower than others. In this research, we develop a statistical method to collect subjective test results and a classification method to automatically learn and generalize the results to unseen network and conversational conditions. We study network-control and scheduling algorithms for improving the asymmetry in silence periods and the quality of speech segments received.