Transmission of variable-rate encoded speech samples on packet radio networks

This paper presents the performance evaluation of different speech coding techniques in wireless packet switching networks: the goal of our study is to increase network capacity while maintaining a smooth degradation of quality at high loads and heavy interference, in order to make it possible for different kinds of information to coexist in a single network infrastructure. In the paper we propose a variable-rate multimode and embedded encoding technique as effective for handling network congestion and channel impairments that both cause discarding or erasure of frames of information. Therefore this approach is important not only in TDMA packet switched communications with statistical multiplexing (leading to greater efficiency and flexibility than basic TDMA, that assigns a fixed portion of channel resources to each user), but also in a CDMA-based mobile system that is strictly limited by interference.