Research On Speech Coding In The Third Generation Of Mobile Communications

The Third Generation of Mobile Communications (3G) is a great revolution in the history of mobile communications, which can provide multimedia service to the mobile users with very high frequency efficiency. Speech coding is a key technique in 3G and will play a very important role in data compression because of its strong ability of reducing the bit-rates of speech signals. AMR(Adaptive Multi-Rate) speech codec is adopted as the speech coding standard in the 3G system. It provides a multitude of different rates according to the local radio channel and traffic conditions, and it can select the optimal channel and codec mode to deliver the best combination of speech quality and system capacity. AMR brings a lot of flexibility to the 3G system.This thesis focuses on the research of the development of AMR speech codec for the 3G system, including:1. Studying in depth on AMR speech coding technique and DSPs(Digital Signal Processors) developing technique, the author has designed the circuit of a single chip DSP system for a 16-channel AMR speech coding/decoding, and cooperatively finished developing the hardware and the software of the AMR codec.2. Researching on echo cancellation algorithm, the author has succeeded in developing a C language program for such an algorithm, which works well and will be a good foundation for its DSPs implementation in the next step.