A soft-switching method for channel equalization algorithms based on decision-annulus rule

In this paper, we introduce and investigate the switching methods between blind equalization and conventional adaptive equalization. As we known, the signal constellation will rotate and appear annulus after transmitting through wireless channel due to the fading and multi-path. So it is necessary to adopt the channel equalization to compensation the channel distortion. In order to obtain the better performance of the channel equalization, we present a new soft-switching method based on decision-annulus rule, it realizes transition automatically and smoothly between constant-modulus algorithm (CMA) and decision-directed least mean square (DD-LMS) algorithm. Combined with this soft-switching method, a new structure to adjust joint blind equalization and carrier recovery is also given for example. Simulation results demonstrate that our soft-switching method outperforms previously proposed hard switching methods. It improves performances of adaptive channel equalization by increasing the convergence rate and enhancing the algorithm stability.