Pre-processing apparatus using nonuniform quantization of channel reliability value and LDPC decoding system using the same

A Low Density Parity Check (LDPC) decoding system using nonuniform quantization of a channel reliability value, comprising:

• a pre-processing means for estimating a discrete channel reliability value within a predetermined range based on a performance simulation result with respect to a bit error rate (BER) according to standard deviation of channel noise, quantizing nonuniformly the channel reliability value of a signal transmitted from the outside into the above estimated discrete channel reliability value, and bit-shifting the receiving signal as much as the quantized discrete channel reliability value;
• an initializing means for initializing the LDPE decoding system based on data transmitted from the pre-processing means;
• a probability calculation iterating means for receiving data from the initializing means, calculating the relationship between parity nodes and bit nodes in a form of a probability, and updating a result obtained from the probability calculation;
• and
• a Log Likelihood Ratio (LLR) calculating means for restoring encoded data by using the data outputted from the probability calculation iterating means.