PSI-CELP speech coder for mobile communications

The mobile telecommunications system is expected to run out of radio channels if the demand continues to grow at the current rate. One of the most feasible ways to relieve this problem is to reduce the bit rate used for speech signal transmission without degrading the quality. As a result of extensive research. NTT group has developed Pitch Synchronous Innovation CELP (PSI-CELP) speech coding method and has achieved quality comparable to the current standard, while using half the bit rate. PSI-CELP has been adopted to the half-rate CODEC standard for digital cellular telecommunication system in Japan.