Soft-combining for linear unequal error protection codes

Soft-combining techniques can be used to provide reliable communication over very noisy channels. This is achieved by repeating and then combining codewords until a desired reliability level has been obtained. The heart of the presented soft-combining approach for linear unequal error protection codes is a maximum a posteriori decoder. The decoding problem is mapped into a spectral domain with a greatly simplified computational structure. The decoder releases soft-output, which is used later on as a priori information for decoding of a retransmitted codeword. Numerical examples show that significant performance improvement can be obtained with soft-combining compared to simple soft decision decoding.