Performance considerations of a 9.6kb/s RELP coder for mobile telephony

The authors present results from tests on a simulated RELP coder for 9.6 kb/s channel rates. Based on the SRELP (second residual-excited LP) coding algorithm, the structure of the coder is described and its features are discussed. Simple forms of error protection combined with smoothing techniques are used in order to improve the robustness of the coder to channel bit errors. The performance of the system is evaluated both objectively and subjectively for error free and simulated channel bit error conditions. A spectral distance measure is used as the objective quality criterion whilst the subjective evaluation is based on mean opinion scores (MOS) listening tests. The results indicate that this coder is an attractive candidate for use in satellite mobile systems