Link Adaptation of LDPC Codes Based on Exponential Effective-SNR Mapping Link Quality Model

Abstract

To improve the flexibility and accuracy of link adaptation (LA) of LDPC coded OFDM system, the classical exponential effective-SNR mapping (EESM) link quality model is extended to LDPC codes. Theoretical analysis and simulation results indicate that by selecting proper modulation and coding adjusting factors, the EESM model is precise for LDPC codes, both in terms of complexity and accuracy for various modulation and coding schemes (MCS), sub- channel states and coding block lengths. Therefore it can be treated as an accurate link to system (L2S) interface for LDPC coded multi-carrier system. To verify it, a new LA scheme based on LDPC codes specified in IEEE802.16e standard is presented. Based on the EESM model, the link-level performance of BPSK over additional white Gaussian noise (AWGN) channel is used to predict the throughput performances of the LA scheme, which match the simulation results very well.