Spatially Coupled LDPC Codes via Partial Superposition

In this paper, we present a new class of spatially coupled low-density parity-check (SC-LDPC) codes, which are constructed by sending codewords of LDPC block code (LDPC-BC) in a block Markov superposition transmission (BMST) manner. Different from the conventional SC-LDPC codes, the proposed SC-LDPC codes can have encoder/decoder implemented with the basis of the hardware components of the corresponding LDPC-BCs. The proposed SC-LDPC codes are also a special class of BMST-LDPC codes. Distinguished from other types of BMST codes, BMST-LDPC codes have lower error floors even with an encoding memory of one and hence have lower decoding latency. Also different from the original BMST codes, partial superposition is implemented to alleviate error propagation. To analyze the bit error rate (BER) performance, we present the genie-aided (GA) bounds, which can be obtained by simulation or estimated from the performance of the basic code. Numerical results are presented to validate our analysis and demonstrate the performance advantage of the BMST-LDPC codes over the LDPC-BCs.