Blind MIMO equalization with tagging filter based on all-pass filter

A blind equalization system using on a pre-filter is proposed for separating the sources in multiple-input multiple-output (MIMO) wireless communication systems. A conventional blind MIMO equalization causes the permutation of the originally transmitted signals, therefore, it is an obstacle to the practical application of a blind MIMO system. In order to solve the problem, each input signal of a proposed MIMO system is pre-filtering by a unique all-pass filter, which is referred to as Transmit tagging filter (TT-Filter) in this paper. At a receiver, an inverse filter of TT-filter is used to blindly equalize a MIMO channel and to retrieve desired signals without any permutation.