A study on tagging filter based on allpass filter for blind MIMO equalization

A blind equalization system using on a pre-filter is proposed for blindly separating constant modulus sources in multiple-input multiple-output (MIMO) wireless communication systems in this paper. With the proposed technique, each modulated signal is pre-filtering based on an allpass filter (transmit tagging filter: TT-filter). At the receiver, a desired signal is generated by filtering with an inverse filter of the TT-filter, and blindly separating a constant modulus signal from non-constant modulus signals and to retrieve desired signals without any permutation of the originally transmitted signals. In addition, the proposed tagging system transforms a blind MIMO problem into a blind single-input multiple-output (SIMO) problem.