Link Adaptation of Rate-Compatible LDPC Coded OFDM System Based on Minus Exponential Effective-SNR Mapping Link Quality Model

An precise but simple link quality model is crucial to improve the accuracy and flexibility of link adaptation design of LDPC coded OFDM system, because it acts as a link-to-system interface which provides system simulator immediately the BLER performance of a certain modulation and coding scheme corresponding to the current SINR states, which is an instantaneous vector. This contribution extends the classical exponential effective-SNR mapping model to rate-compatible LDPC codes. Theoretical analysis and simulation results indicate that the EESM model eliminates the influence of different modulation modes and channel states, by selecting proper modulation and coding adjusting factors. Therefore it can be treated as an accurate link to system interface for LDPC coded OFDM system. Furthermore adaptive modulation and coding scheme is designed to verify the accuracy of the model. The predicted results match the simulation ones very well, both over AWGN and TU50 channels, which confirms that the EESM model offers accurate and convenient look-up tables for LA design of LDPC coded OFDM system.