Implicit Globally-Coupled LDPC Codes Using Free-Ride Coding

In this paper, we present a new construction of the globally-coupled LDPC (GC-LDPC) codes, referred to as implicit GC-LDPC codes, where the additional global parity-check bits are transmitted using the free-ride coding. The presented GC-LDPC codes have the same rates as the component LDPC codes, avoiding the rate reduction caused by the global parity checks for the conventional GC-LDPC codes. Moreover, the encoders of the component LDPC codes are reusable in the presented GC-LDPC codes, a distinguished feature as compared with the conventional GC-LDPC codes. The simulation results show that the proposed implicit GC-LDPC codes can improve the performance of the component LDPC codes, yielding extra coding gain of up to 0.7 dB (with (3,6)-regular LDPC codes as the component codes) and 0.5 dB (with IEEE 802.16e LDPC codes as the component codes).