MET-DE Aided Design of Low-Rate DTMB-A LDPC Codes

DTMB-A adopts LDPC codes with three code rates 1/2, 2/3 and 5/6, and low-rate LDPC codes are needed by DTMB-A to support scenarios which require low spectral efficiency and carrier-to-inference ratio. In this paper, a potential design of low-rate DTMB-A LDPC codes is presented. The newly-designed LDPC codes employ a lower-triangular Raptor-like base matrix, which is carefully optimized by multi-edge-type density evolution (MET-DE). A more detailed cycle classification method is proposed to mitigate the error floor of the newly designed codes, while progressive lifting is employed to keep the feature of length-scalability. BER and BLER simulation results are presented, which demonstrates that the newly-designed low-rate DTMB-A LDPC codes have better performance than ATSC 3.0 Type-A LDPC codes with similar code lengths, within both waterfall region and error floor region, and over both BI-AWGN and Rayleigh fading channels.