Simulation Probability Density Function Design for Turbo Codes

Fast simulation of turbo codes over AWGN channels

“…The optimum conditional distribution given in (15) is similar to equations (13) and (14) of [8]. However, the author uses the optimum condition distribution in a different manner in his application of IS.…”

“…However, the author uses the optimum condition distribution in a different manner in his application of IS. In [8], the set of all error patterns is replaced with groups of error patterns from the smallest Hamming distance. In each simulation run, the optimum conditional distribution is approximated.…”

“…The advantage of this method is that it can evaluate all possible error patterns instead of 'aiming' ones. However, this method works only at low SNRs and does not give accurate estimates at high SNRs as shown in the results of [8].…”

“…Therefore, it can be seen that error event simulation method is not a good IS approach for turbo coded systems. A more efficient method, which behaves similar to MC simulation, has been proposed in [8]. The advantage of this method is that it can evaluate all possible error patterns instead of 'aiming' ones.…”

“…Our approach is based on the most probable error path (MPEP) method which shifts the input pdf to the mode of the optimal distribution where most probable errors are located [9]. It should be noted that the MPEP method has been considered in [8]. However, the author uses the optimal distribution in a different manner in his application of IS.…”