Design of repeat-accumulate codes for iterative detection and decoding

Extrinsic information transfer (EXIT) charts are used to design systematic and nonsystematic repeat-accumulate (RA) codes for iterative detection and decoding. The convergence problems of nonsystematic RA codes are solved by introducing a biregular, or doped, layer of check nodes. As examples, such nonsystematic codes are designed for multi-input/multi-output (MIMO) fading channels and are shown to operate close to capacity.