Tagging-filter based blind MIMO equalization without signal permutation

In this paper, we propose a signal processing technique for blindly separating constant modulus sources in wireless communication systems. With the proposed technique, each source is pre-filtered using a unique allpass filter that we refer to here as a transmit tagging filter (TT-filter). At the receiver, an inverse model of the TT-filter is used to blindly equalize a multiple input multiple output (MIMO) channel and to retrieve desired signals without any permutation of the originally transmitted signals. This represents an important improvement over the conventional blind method, in which permutation of transmitted signals is known to accompany blind MIMO equalization. Computer simulations with constant modulus sources verify the effectiveness of the proposed system