Variable rate speech coding techniques for the DECT system

In this contribution, variable rate coding techniques are proposed to improve the speech quality of the DECT system in poor channel conditions. The basic idea is to estimate in advance the quality of the channel, and subsequently select the best source-channel rate combination. The channel quality is predicted from the characteristics of the signal received in previous frames. The introduction of G.727 variable rate embedded speech coder, combined with FEC codes provides the rate adaptation. Objective quality measurements demonstrate the possibilities of this approach.