WCDMA Source Coding
AMR (Adaptive Multi-Rate) Speech
- A integrated speech codec with 8 source rates
- The AMR bit rates can be controlled by the RAN depending on the system
load and quality of the speech connections
Video Phone Service
- H.324 is used for VP Service in CS domain
- Includes: video codec, speech codec, data protocols, multiplexing and etc.
- AMR is compatible with current mobile communication system (GSM, IS-95, PDC and so on), thus, it will make multi-mode terminal design easier.
- The AMR codec offers the possibility to adapt the coding scheme to the radio channel conditions. The most robust codec mode is selected in bad propagation conditions.
- The codec mode providing the highest source rate is selected in good propagation conditions.
- During an AMR communication, the receiver measures the radio link quality and must return to the transmitter either the quality measurements or the actual codec mode the transmitter should use during the next frame. That exchange has to be done as fast as possible in order to better follow the evolution of the channel’s quality.