Application and standardization of turbo codes in third-generation high-speed wireless data services

This paper addresses the application of turbo codes for third-generation wi reless services. It describes the specific characteristics of high-rate dat a applications in third-generation wide-band code-division multiple-access (CDMA) systems that make turbo codes superior to convolutional codes. In pa rticular it shows the positive effect of fast power control employed in the se systems on the relative performance of turbo codes,with respect to convo lutional codes, It also shows how turbo and convolutional codes behave diff erently when the figure of merit is changed to frame error rate from bit er ror rate for high-speed data services. Furthermore, it describes in detail how and why the standardized turbo code has been selected in the presence o f other candidates, which were also based on iterative decoding. Details of turbo interleaving and trellis termination as specified in the standards a re explained, performance of turbo codes under wide-band CDMA operating con ditions are presented. The suitability of turbo codes for low-rate data app lications is discussed. Finally, it is shown that the performance loss as a result of internal decoder parameter quantization is negligible.