Link adaptation to channel interference using multi-rate source and channel coding for CDMA mobile communications

This paper investigates the benefits of link adaptation according to the propagation conditions using multi-rate vocoders and channel coders. A multi-rate source and channel coding (MRC) system trades-off the source codec bit rate against channel codec bit rate according to the prevailing channel conditions. MRC systems continuously reconfigure transmission resources to optimally combat channel degradations and hence, maintain a reasonable quality of service even in marginal channel conditions. The aim is to maintain a satisfactory level of speech quality over a wide range of channel conditions with minimum resources. This paper shows the benefit of MRC system particularly in crowded cells of high channel interference.