Design of Multi-Edge-Type Bilayer-Expurgated LDPC Codes for Decode-and-Forward in Relay Channels
The authors consider the design of Bilayer-Expurgated Low-Density Parity-Check (BE-LDPC) codes as part of a decode-and-forward protocol for use over the full-duplex relay channel. A new ensemble of codes, termed Multi-Edge-Type Bilayer-Expurgated LDPC (MET-BE-LDPC) codes, is introduced where the BELDPC code design problem is transformed into the problem of optimizing the multinomials of a multi-edge-type LDPC code. They propose two design strategies for optimizing MET-BE-LDPC codes; the bilayer approach is preferred when the difference in SNR between the source-to-relay and the source-to-destination channels is small, while the bilayer approach with intermediate rates is preferred when this difference is large. In both proposed design strategies multi-edge-type density evolution is used for code optimization.