Voice over Internet Protocol (VoIP) Packet Loss Concealment (PLC) by redundant transmission of speech information

As telephone service is digitized, a need arises to merge the existing telephone network into the recently created Internet data network. This has been achieved through the field of Voice over Internet Protocol (VoIP), which offers many solutions, but also poses some very interesting challenges.; This thesis studies the challenge of protecting transmitted voice packets from the inevitable erasures and delays imposed by the Internet. As a solution to this uniquely defined problem the thesis contributes the original concept of Cross Packet Redundancy (CPR), a general scheme for the redundant coding of speech information in order to protect packets (and thus provide superior user quality) at high packet loss rates.; As opposed to other Packet Loss Concealment (PLC) schemes, which aim to optimize bandwidth usage and computational complexity, the advantage of the CPR is that it aims to maximize the perceived speech signal quality. This is achieved by redundantly transmitting the most important information from the speech signal in PLC streams of adjacent packets. The added bandwidth cost provides good PLC results.; Chapter 3 introduces the proposed CPR scheme, while Chapters 4 and 5 provide and evaluate two implementations of the proposed scheme. Chapter 6 illustrates an application of the principles of CPR in the ITU G.729 Annex I AS-CELP coder.