ANALYTICAL DERIVATION OF EXIT CHARTS FOR SIMPLE BLOCK CODES AND FOR LDPC CODES USING INFORMATION COMBINING

The extrinsic information transfer (EXIT) chart describes the input-output behavior of a decoder by means of the map-ping from a-priori information and channel information to extrinsic information. In this paper, we consider single par-ity check and repetition codes over binary-input symmet-ric memoryless channels. Using the concept of information combining, we derive bounds on the extrinsic information for these codes, which depend only on the a-priori informa-tion and on the channel information, but not on the channel models. The bounds are applied to the EXIT charts of these codes and to the EXIT charts of low-density parity-check codes. 1