Delay, jitter and packet loss significantly degrade the speech quality in VoIP applications, especially in VoWLAN. In order to solve this problem, different jitter buffer and error concealment techniques are introduced. In this paper, we propose a new simple but effective error concealment method for VoIP, which uses the contour tendency of the last two packets to predict and recover the current packet. We combine fixed jitter buffer with different receiver-based error concealment methods and use PESQ scores to compare their performances. A real WLAN system (802.1 Ib) is set up and real trace files are used. Experiment results show that the new method outperforms other one-sided error concealment methods. It even outperforms some of the two-sided error concealment methods with much less delay
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