Hi,
I understand that you have already implemented OFDM channel estimation using LS estimator and now want to implement the same in using MMSE estimator. Besides analytical calculations, MMSE estimator can also be computed numerically by first generating a set of training data, i.e., channel vectors and observations, from conditional channel model or through a long-term collection of measurements. Later an optimization algorithm can be used to compute a function the empirical squared estimation error.
Following are some of the links which may help you to implement OFDM channel estimation using MMSE estimator.
