Turbo detection and variable rate coding in systems using linear block codes and block interleavers

Linear block coding with an iterative detecting-decoding process, namely turbo detection, is examined for data transmission within the framework of the HIPERLAN Type 1 system. By means of simulations, performance is evaluated in Gaussian and Rayleigh fading channels. The turbo detection method is shown to offer superior performance when compared to soft-decision algorithms, although its high potentialities are limited by the predefined standard. Furthermore, in order to improve the performance we consider the possibility of applying turbo detection to a system having the same physical layer as HIPERLAN, except the single error-correcting BCH(31,26) code is replaced with a 3 error-correcting BCH(31,16) code, or with a 7 error-correcting BCH(31,6) code. Beside having good performance, this approach is very modular since its structure adapts to different information rates, furthermore it allows the system to work at lower signal-to-noise ratios