Affine Projection Algorithms with Novel Schemes of Variable Projection Order

The projection order of the affine projection algorithm (APA) affects not only the convergence performance but also the steady-state behavior. Therefore, for solving the fixed projection order of the conventional APA, we develop a new scheme of variable projection order (VPO) that enables the evolution from the maximum projection order to the minimum one by resorting to the adaptation of the mixing factor, thereby yielding a novel APA with VPO. Moreover, for dealing with sparse systems with fast convergence, we extend the proposed VPO scheme to proportionate APA and develop a VPO-based memory proportionate APA. Simulation results in the scenarios of system identification and acoustic echo cancellation have shown that the proposed algorithms have a faster convergence rate and lower steady-state error as compared to their original counterparts and the existing VPO algorithms.