According to one embodiment there is provided a method of determining receiver beam forming vectors for a plurality of receivers in a MIMO system. Each receiver comprises a plurality of receiver antennae. The MIMO system also comprises a plurality of transmitter antennae. The method comprises quantifying the properties of the channels of the MIMO system in a channel property matrix including interference between individual channels and performing Cholesky decomposition of the receiver property matrix row-by-row into a lower triangular matrix with unit elements along its diagonal, a diagonal matrix and the Hermitian transpose of said triangular matrix. Performing the Cholesky decomposition comprises determining, when performing a step of the Cholesky decomposition for a row, a receiver-beam forming vector associated with the row that maximises the component of the diagonal matrix in the row.