Blind adaptive equalizer based on locally generated sub-carrier

In this paper we propose a blind adaptive algorithm based on locally generated sub-carrier. We consider a quadrature phase shift keyed (QPSK) signal as the transmitted signal, and assume that the orthogonal sub-carriers or the intermediate frequency used to generate the transmitted signal are well known. The proposed algorithm combines two algorithms: Namely, the least mean square (LMS) algorithm which has a cost function with unique minimum, and the constant modulus algorithm (CMA), which was first proposed by Godard. By doing this and operating the equalizer at a rate greater than the symbol rate, we take advantage of the variable amplitude of the sub-carriers so as to achieve a faster convergence speed. When the computer simulation results of the proposed algorithm are compared with the constant modulus algorithm (CMA) and the modified CMA (MCMA), we observed that the proposed algorithm exhibited a faster convergence speed.