Switching Mechanism on the Order of Affine Projection Algorithm

Conventional affine projection (AP) algorithm with a fixed order is subject to a tradeoff between convergence speed and steady-state misalignment. In order to address such problem, a switching mechanism on the order of AP algorithm is proposed by comparing the performance of two AP algorithms with different orders. Firstly, the mean square deviations (MSD) behavior of the AP algorithm is analyzed, and a calculation formula for computing MSD at each iteration is derived. Secondly, we design a switching mechanism to select the better order of the two AP algorithms by comparing the MSDs of them; the MSD of the chosen order is smaller than that of the other. We also give the theoretical analysis, including steady-state mean square error (MSE) and computational complexity. Finally, the experiments in system identification and echo-cancellation scenarios demonstrate that the proposed algorithm has good performance not only in a stationary environment but also in a non-stationary environment.