Real-time turbo decoding of block turbo codes using the Hartmann-Nazarov algorithm on the DSP Texas TMS320C6201

Product codes were introduced in 1954 by Elias and consist of a serial concatenation of two linear block codes with an uniform interleaver. The coding process only uses two linear block codes and creates a matrix in which both columns and rows are codewords. The decoding process can use different algorithms. After first implementing the Chase algorithm, we present another decoding process including the Hartmann-Nazarov (1976, 1998) algorithm and the fast Hadamard transform (FHT). This algorithm uses a symbol-by-symbol decoding rather than a whole word decoding. The decoding process is implemented on the fixed point DSP TMS320C6201. It communicates, via the RTDX link, with the coder, written in C++ language and running on the PC. The Hartmann-Nazarov algorithm exhibits better performance on the Rayleigh channel. A first evaluation of the bit rates gives us a value close to 500 kbits/s on the DSP clocked at 250 MHz.