基于NS-2低丢包率自适应多速率VoIP系统的QoS研究

QoS保障对于语音电话VoIP系统是个关键性问题,但目前采用固定速率传输的传统VoIP系统存在着网络丢包问题,尤其是连续丢包会导致语音QoS严重下降.鉴于此提出一种比传统系统更具QoS保障的VoIP新的系统方案,该系统方案采用能更真实反映网络状况的丢包率计算公式,并以此作为系统有效调整速率的依据.同时进行了NS-2仿真实验,分析了该新系统在QoS保障方面的性能与优势.仿真实验的结果表明:所提出的VoIP新系统方案在语音QoS保障方面,明显优于已有的VoIP系统.

QoS Study of Low Packet-Loss-Ratio VoIP System Based AMR Using NS-2

The QoS assuring is the key component of the VoIP(Voice over IP) system.The traditional VoIP systems are based on the speech codec with a fixed rate,having the problem of packet-loss,especially for continuous packet-loss.The degradation for the speech quality would be seriously caused by this kind of problem.To settle the above problem,the paper presents a new VoIP system which is better in the QoS assuring.The system adopts a formula for the packet-loss-ratio which can more effectively reflect the actual network condition.It adjusts its speed according to the above ratio.Finally,the paper analyzes the performance of the proposed system in QoS assuring of the VoIP system using NS-2.The simulation results show that the proposed system outperforms the previous VoIP systems at the aspect of QoS assuring.