A new dual-mode blind equalization approach based on modified super-exponential iteration algorithm

Blind adaptive equalization plays an extremely important role in digital wireless radio communications. Convergence rate and residue mean square error (MSE) are two main parameters in evaluating the performance of blind equalization algorithms. The iteration form of the super-exponential (SEI) algorithm, which was proposed by Shalvi and Weinstein, converges fast, but its residue MSE is large when used for higher-order quadrature amplitude modulation (QAM) signals. A modified algorithm of the SEI (MSEI) was introduced for digital wireless radio channels, and it is capable of correct the phase rotation of the carrier frequency as well as has a fast convergence rate. On this condition, a kind of dual-mode blind equalization method was proposed. At the beginning of the iteration process, the MSEI algorithm was used. When the MSE level was reduced to a certain level, the iteration mode switched to the decision directed (DD) algorithm. This switch method can achieve less residue mean square error for high order QAM signals. The performance of the proposed algorithms is validated by computer simulations.