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-Among various decoding algorithms of low-density parity-check (LDPC) codes, the minsum (MS) algorithm and its modified algorithms are widely adopted because of their computational simplicity compared to the sum-product (SP) algorithm with slight loss of decoding performance. In the MS algorithm, the magnitude of the output message from a check node (CN) processing unit is decided by either the smallest or the next smallest input message which are denoted as min1 and min2, respectively. It has been shown that multiplying a scaling factor to the output of CN message will improve the decoding performance. Further, Zhong et al. have shown that multiplying different scaling factors (called a 2-dimensional scaling) to min1 and min2 much increases the performance of the LDPC decoder. In this paper, the simplified 2-dimensional scaled (S2DS) MS algorithm is proposed. In the proposed algorithm, we figure out a pair of the most efficient scaling factors which multiplications can be replaced with combinations of addition and shift operations. Furthermore, one scaling operation is approximated by the difference between min1 and min2. The simulation results show that S2DS achieves the error correcting performance which is close to or outperforms the SP algorithm regardless of coding rates, and its computational complexity is the lowest comparing to modified versions of MS algorithms.

Conditional termination check min-sum algorithm (MSA) using the difference of the first two minima is proposed for faster decoding speed and lower power consumption of low-density parity-check (LDPC) code decoders. Judging from the size of the difference in LDPC decoding scheduling, the proposed method dynamically decides whether the termination checking steps will be skipped or not. The simulation results show that the decoding speed is improved up to 7%, and the power consumption is reduced by up to 16.43% without any loss of error correcting performance. Also, the additional hardware cost of the proposed method is negligible compared to conventional LDPC decoders.

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