A CSI and Rate-Distortion Based Packet Loss Recovery Algorithm for VoIP

Packet loss affects the received speech quality greatly in VoIP (Voice over Internet Protocol) applications. PCM (Pulse Code Modulation) coders are often used for VoIP and also face such problems. In this paper, a packet loss recovery algorithm is proposed based on CSI (Coding with Side Information) and Rate-Distortion optimization. Two virtual reconstruction methods are implemented for every voiced packet with side information at the sender endpoint. Rate-Distortion optimization is used to select the proper recovery method which has the lowest cost considering both the distortion and rate. At the receiver endpoint, the lost packets will be recovered with the selected recovery method. Simulation results show that the speech quality over IP network is improved dramatically at the price of only a low bandwidth consumption with the proposed method.