Spatially coupled protograph-based LDPC codes for incremental redundancy

We investigate a family of protograph based rate-compatible LDPC convolutional codes. The code family shows improved thresholds close to the Shannon limit compared to their uncoupled versions for the binary erasure channel as well as the AWGN channel. In fact, the gap to Shannon limit is almost uniform for all members of the code family ensuring good performance for all subsequent incremental redundancy transmissions. Compared to similar code families based on regular LDPC codes [1] the complexity of our approach grows slower for the considered rates.