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| Study of the Performance Sensitivity to SNR Mismatch in BICM-ID System |
| Zou Xue-lan; Feng Guang-zeng |
| College of Communication and Information Engineering, Nanjing University of Posts and Telecommunications, Nanjing 210003, China |
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Abstract The iterative decoding schemes such as BICM-ID and other concatenated coding systems require the knowledge of channel Signal-to-Noise Ratio (SNR). The effect of SNR estimation errors is studied for BICM-ID in the paper and the performance sensitivity of SNR mismatch for the log-APP decoding algorithm and its simplified implementations is analyzed. Analysis and simulation results show that the max-log-APP algorithm is robust against any SNR mismatch problem, while the log-APP algorithm and other simplified implementations are more tolerant of overestimation of SNR than underestimation, which is because they use different correction functions. The required SNR accuracy to prevent large performance degradation is increased with the increase of channel SNR, generally from -2dB to +6dB. Therefore, when there is no perfect channel state information, the max-log-APP algorithm is the optimum decoding algorithm for BICM-ID.
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Received: 25 July 2007
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2008, Vol. 30 
