Iterative Block Decision Feedback Equalization for the Hybrid Carrier System

The hybrid carrier (HC) system based on the weighted-type fractional Fourier transformation (WFRFT) can be seen as a generalized form of the single-carrier (SC) system and the multi-carrier (MC) system. Focused on the non-linear equalization of the HC system, we propose a novel iterative block decision feedback equalization (IBDFE) algorithm to improve the bit error rate (BER) performance under doubly selective channels. Two design methods are considered according to the minimum mean square error (MMSE) criterion. In the first method, the hard detection (HD) is performed and the equalizer is designed based on the correlation between the hard detected data and the transmitted data. Besides, in the second method, the soft detection (SD) is employed and the equalizer is designed by the soft detected data. The interference in the HC system can be suppressed effectively by employing the proposed IBDFE. The complexity in terms of the number of complex multiplications is also analyzed. Numerical results indicate that the IBDFE outperforms existing linear MMSE equalization regarding the BER performance.