Blind adaptive MIMO decision feedback equalization using Givens rotations

An adaptive method is proposed for multiple-input-multiple-output (MIMO) decision feedback equalization (DFE) in the absence of channel knowledge at the receiver and without requiring a training sequence. The zero-forcing (ZF) DFE is shown to consist of an orthogonal matrix (feedforward section) and an upper triangular matrix (feedback section). The feedforward matrix is expressed as the multiplication of Givens rotations terms, where each term is characterized by a rotation angle. An adaptive algorithm is presented for the blind determination of the unknown angles and of the elements of the feedback matrix. The adaptation criteria are decorrelation conditions. Simulation results are included demonstrating the performance of the method.