Reduced order RLS rational function predistortion

In this paper, a modified recursive least square (RLS) based rational function predistortion is proposed by reducing the order of the rational function used in the RLS algorithm. First, The rational function structure is transformed into polynomial structure. Thus, the basic idea of the reduced order RLS based polynomial predistortion algorithm is used, system structure is same to original, only the algorithm of adaptation process is modified to approximate the target function with two simpler functions. A complex function is decomposed into two simpler functions so that we can compute the RLS algorithm with much less complexity. The proposed reduced order RLS algorithm rational function predistortion show superior performance compared to the conventional RLS rational function predistortion with the same computational complexity or with the same number of coefficient.