Methods and apparatus for sub-block based architecture of Cholesky decomposition and channel whitening. In an exemplary embodiment, an apparatus is provided that parallel processes sub-block matrices (R00, R10, and R11) of a covariance matrix (R) to determine a whitening coefficient matrix (W). The apparatus includes a first LDL coefficient calculator that calculates a first whitening matrix W00, lower triangle matrix L00, and diagonal matrix D00 from the sub-block matrix R00, a first matrix calculator that calculates a lower triangle matrix L10 from the sub-block matrix R10 and the matrices L00 and D00, and a second matrix calculator that calculates a matrix X from the matrices D00 and L10. The apparatus also includes a matrix subtractor that calculates a matrix Z from the matrix X and the sub-block matrix R11, a second LDL coefficient calculator that calculates a third whitening matrix W11, lower triangle matrix L11, and a diagonal matrix D11 from the matrix Z, and a third matrix calculator that calculates a second whitening matrix W10 from the matrices L00, L10, L11, and D11.