VHDL Implementation of different Turbo Encoder using Log-MAP Decoder

Turbo code is a great achievement in the field of communication system. It can be created by connecting a turbo encoder and a decoder serially. A Turbo encoder is build with parallel concatenation of two simple convolutional codes. By varying the number of memory element (encoder configuration), code rate (1/2 or 1/3), block size of data and iteration, we can achieve better BER performance. Turbo code also consists of interleaver unit and its BER performance also depends on interleaver size. Turbo Decoder can be implemented using different algorithm, but Log –MAP decoding algorithm is less computationaly complex with respect to MAP (maximux a posteriori) algorithm, without compromising its BER performance, nearer to Shannon limit. A register transfer level (RTL) turbo encoder is designed and simulated using VHDL (Very high speed integrated circuit Hardware Description Language). In this paper VHDL model of different turbo encoder are implemented using Log MAP decoder and its performance are compared and verified with corresponding MATLAB simulated results.