Design methods for irregular repeat accumulate codes

We optimize the low-complexity random-like ensemble of irregular repeat accumulate (IRA) codes for binary-input symmetric channels in the large blocklength limit. IRA codes Jin, H et al. (2000) are special subclasses of both irregular LDPCs and irregular turbo codes. We present numerical results for the BIAWGNC and formulate the density evolution (DE) Richardson, TJ et al. (2001) for IRA codes. We study the stability condition of the fixed-point corresponding to zero BER.