In this paper, a reduced complexity Log-MAP algorithm based on a non-recursive approximation of the max*\r\noperator is presented and studied for turbo trellis-coded modulation (TTCM) systems. In the algorithm, denoted as\r\nAvN Log-MAP, the max* operation is generalized and performed on n = 2 arguments. The approximation is derived\r\nfrom the Jensen inequality. The non-recursive form of the max* calculations allows to achieve significant reduction in\r\nthe decoding effort in comparison to the conventional Log-MAP algorithm. Bit-error rate performance simulation\r\nresults for serial and parallel TTCM schemes in the additive white Gaussian noise and uncorrelated Rayleigh fading\r\nchannels show that the AvN Log-MAP algorithm performs close to the Log-MAP. Performance and complexity\r\ncomparisons of the AvN Log-MAP algorithm against the Log-MAP and several relevant reduced complexity turbo\r\ndecoding algorithms proposed in the literature reveal, that it offers favorable low computational effort for the price of\r\nsmall performance degradation.
Loading....