The effect of noise estimation error in the LDPC decoding performance

The number of quantization bits of the input signals r_n needs to be optimally determined through the trade-off between the H/W complexity and the BER performance in LDPC codes applications. Also, an effective means to incorporate a channel reliability L_c in the log-MAP based LDPC decoding is highly required, because it has a major effect on both the complexity and performance. In this paper so as to effectively incorporate L_c in LDPC decoding. The optimal number of quantization bits of r_n is investigated through Monte-Carlo simulations assuming that bit-shifting approach is adopted. In addition, the effects of an incorrect estimation of noise variance on the performance of LDPC codes are investigated. There is a confined range in which the effects of an in correct estimation can be ignored