Spatially “Mt. Fuji” coupled LDPC codes

A new type of spatially coupled low density parity check (SCLDPC) codes is introduced. These codes have exponentially increasing nodes as position goes to the middle of the chain. We call the codes spatially "Mt. Fuji" coupled LDPC (SFCLDPC) codes because the shape constructed by the number of nodes looks like "Mt. Fuji". By this structure, the SFCLDPC codes have the rate loss O(α
^-L
), while the usual SCLDPC codes have O(L
^-1
). In addition, the decoding processes for the SFCLDPC codes are accelerated exponentially fast as the iteration progresses. An infinite length analysis for the SFCLDPC codes with the density evolution and a finite length performance comparison between the SFCLDPC codes and the SCLDPC codes with computer simulations are made.