  A novel approach for solving linear estimation problem in multi-user massive
MIMO systems is proposed. In this approach, the difficulty of matrix inversion
is attributed to the incomplete definition of the dot product. The general
definition of dot product implies that the columns of channel matrix are always
orthogonal whereas, in practice, they may be not. If the latter information can
be incorporated into dot product, then the unknowns can be directly computed
from projections without inverting the channel matrix. By doing so, the
proposed method is able to achieve an exact solution with a 25% reduction in
computational complexity as compared to the QR method. Proposed method is
stable, offers an extra flexibility of computing any single unknown, and can be
implemented in just twelve lines of code.
