1. A method of estimating an Orthogonal Frequency Division Multiplex (OFDM) channel, implemented in a wireless communications device, the method comprising: estimating, by the wireless communications device, a channel matrix using a basis expansion model (BEM); reducing, by the wireless communications device, a dimension of the estimated channel matrix by computing a coefficients matrix of the estimated channel matrix using a sub-space tracking algorithm; estimating, by the wireless communications device, each coefficient in the coefficients matrix using an iterative conjugate gradient algorithm, wherein a number of iterations performed is less than a number of variables to be solved; and estimating, by the wireless communications device, a transmitted symbol based on the estimated coefficient and a received symbol.