Interpolation-based efficient matrix inversion for MIMO-OFDM receivers

The use of orthogonal frequency-division multiplexing (OFDM) drastically simplifies receiver design in multiple-input multiple-output (MIMO) wireless systems. Nevertheless, MIMO-OFDM receivers are computationally very demanding since processing is performed on a tone by tone basis with the number of data-carrying tones ranging from 48 (as in the IEEE 802.11a/g standards) to 6817 (as in the DVB-T standard). In this paper, we present a new class of algorithms for computationally efficient channel inversion in MIMO-OFDM zero-forcing receivers. The basic idea of the proposed approach is based on the fact that even though the inverse of a polynomial matrix is generally not polynomial, the adjoint and the determinant will be polynomial, which allows efficient inversion of the individual matrices through interpolation. We perform an in-depth complexity analysis of the new class of interpolation-based inversion algorithms. For the system parameters employed in the IEEE 802.16a standard, we demonstrate computational cost savings of up to 80 % over brute-force per-tone matrix inversion.