An estimation-based approach to Multiple-Input Multiple-Output (MIMO) channel equalization

The purpose of this paper is to propose and investigate a new approach to implementing a spatio-temporal Decision Feedback Equalizer (DFE) for MIMO (Multiple-Input Multiple-Output) channels. A system with an array of n transmit and m receiver antennas where (m greater than or equal to n) is assumed Both finite-length (Finite Horizon) and infinite-length (Infinite Horizon) MIMO Decision Feedback Equalizers are considered. We also assume an ISI (Inter-Symbol-Interference) MIMO channel, which means the channel matrix elements are frequency selective. For the infinite-length case the DFE problem leads to solving a matrix spectral factorization. For the finite-length case the DFE problem leads to solving a corresponding Cholesky factorization. Using the estimation-based spectral factorization we have shown that the solution to the infinite-length MIMO DFE is not unique, lit the finite-length case the estimation-based approach leads to a recursive algorithm to perform the Cholesky factorization. The proposed recursive algorithm has low complexity and is also simple to implement. Moreover it leads to a closed form solution for the MIMO DFE matrices.