Reducing the error floor in turbo codes by using non-binary constituent encoders

We propose the utilization of non-binary trellis codes as constituent codes for turbo codes. This allows to increase the free distance of the resulting turbo code with respect to traditional schemes, and leads to a reduction in the error floor. The price to pay is a slight performance degradation at low values of E_b/N₀. The proposed approach can be applied with other techniques based on interleaver design, therefore producing further reduction in the error floor