Abstract: Effects of noise variance estimation on the LDPC decoding performance are investigated. Based on the algorithm of expectation-maximization (EM), a noise variance estimation method is obtained.The method is applied to the BP decoding algorithm . Simulations show that, with the proposed method, the observed performance degradation is less than 0.1dB when the noise variance is unknown.

Key words: LDPC, expectation-maximization algorithm, noise variance estimation