Design of LDPC codes for BP algorithm with channel estimation error

Conference: TURBO - CODING - 2006 - 4th International Symposium on Turbo Codes & Related Topics; 6th International ITG-Conference on Source and Channel Coding
04/03/2006 - 04/07/2006 at Munich, Germany

Proceedings: TURBO - CODING - 2006

Pages: 6Language: englishTyp: PDF

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Saeedi, Hamid; Banihashemi, Amir H. (Department of Systems and Computer Engineering, Carleton University, Ottawa, ON, Canada)

When belief propagation (BP) algorithm is used to decode low-density parity-check (LDPC) codes over the binary input additive white Gaussian noise (BIAWGN) channel, the knowledge of the channel noise power is necessary for the algorithm to achieve its predicted performance. If the noise power is estimated erroneously, we refer to this as “signal to noise ratio (SNR) mismatch”. In this paper, irregular LDPC codes are designed that perform better (have a lower SNR threshold) in the presence of mismatch compared to conventionally designed irregular LDPC codes that are optimized for zero mismatch. It is shown that with a negligible performance loss at zero mismatch, highly irregular codes that are more robust against mismatch can be designed. A method to generate EXIT curves in the presence of mismatch is proposed that will be used to design such irregular codes. Finite block length simulation results are provided to confirm the asymptotic analysis results.