Blind channel identification and equalization using periodic modulation precoders: Performance analysis

The present paper deals with blind identification and equalization of commu nication channels within the so called modulation induced cyclostationarity (MIC) framework, where the input symbol stream is modulated by a P periodi c precoder with the purpose of inducing cyclostationarity in the transmit s equence. By exploiting the cyclostationarity induced by the periodic precod er, a subspace-based channel identification algorithm that is resilient to the location of channel zeros, channel order overestimation errors, and col or of additive stationary noise, is developed, The asymptotic performance o f the subspace-based identification approach is analyzed and compared with the asymptotic lower bound provided hy the nonlinear cyclic correlation mat ching approach. Criteria for optimally designing the periodic precoder are also presented. The performance of MMSE-FIR and MMSE-DFE equalizers is quan tified For the proposed cyclostationarity-induced framework in terms of the MMSE. Although cyclostationarity-inducing transmitters present several adv antages relative to their stationary counterparts from a channel estimation viewpoint, it is shown that from an equalization viewpoint, MIG-based syst ems exhibit a slightly increased MMSE/BER when compared with the stationary case.