A method of Hybrid Automatic Repeat Request implementation which efficiently combines received signals from multiple H-ARQ block transmission attempts encoded by the Multi-Level Coding approach with an uncoded subset of information bits, is presented. The method provides full error correction gains of the H-ARQ scheme and decoder computational complexity reduction due to transmission of uncoded bits that does not cause significant demodulator and signal processing complexity growths.
The advantages are achieved via calculation of likelihood ratio metrics and the combination of at least two different data block transmission attempts for both encoded and uncoded bits of a data block. Additionally, the calculation of likelihood ratio metrics for uncoded bits is performed in consideration of the results of the decoding of the encoded bits. Receiver decisions are then determined on values of uncoded bits based on values of the combined likelihood ratio metrics for uncoded bits.