CTH11-4: On Lowering the Error Floor of High Order Turbo BICM Schemes Over Fading Channels

A new approach for the association of the well known turbo codes to modulation schemes is presented. This method is designed for flat fading channels. It presents the advantage of lowering the error floor as the modulation order increases when compared to the traditional pragmatic turbo BICM approach. The improvement in performance comes at the price of a relatively small added complexity without sacrificing the iterative process convergence. The proposed modifications address mainly the modulator and the corresponding demodulator. An improvement exceeding 0.8 dB is observed at BER rates lower than 10^-7.