Evaluation of trellis termination strategy for turbo codes in UMTS

In English This input document proposes a trellis termination startegy for turbo codes in UMTS. The proposal is based upon the fact that the extrinsic information used in the decoding of turbo codes mitigates the effect of a truncated trellis, and that this mitigating effect can be enhanced by imposing certain restrictions on the interleaver design. The simulation parameters used in the comparison bewteen different methods complies with the parameters described in Tdoc SMG2 UMTS-L1 385/98, except in one point: they are not restricted to the reference pseudo-random interleaver provided by HNS. The reason for this is the close interaction between interleaver design and trellis termination. We recommend that the choice of trellis termination method and interleaver design should be done together, and not as separate optimizations.