Performance evaluation of an 8 kbps speech coder for a land mobile radio at 1.5 GHz

The authors present results from tests on an LSR-FEC (lower-shift RELP with forward error correction) coder for 8-kb/s channels and consider issues related to the operation of the coder in mobile telephone systems. The simple error protection scheme combined with smoothing techniques on the residual signal reconstruction contribute to robustness of the coder at error rates up to 1%. An implementation of the LSR-FEC coder in real time on commercially available hardware is described. The coder showed performance equivalent to 16 kb/s CVSD (continuous variable slope delta modulation) on the mean opinion scores scale under noisy conditions. The results of these experiments indicate that the coder, with digitized speech transmission at 1.5 GHz, is an attractive candidate for use in a mobile radio system