An improved adaptive channel estimation method for multiuser multiantenna OFDM systems

An improved normalized least-mean squares (NLMS) channel estimation method using a time-varying convergence factor is proposed for multiuser and multiantenna systems. The new method does not need to estimate the scalar ambiguity matrix, and is guaranteed to be convergent to the Wiener solution in the mean square sense. Comparing with the basic NLMS algorithm, the improved method has a faster convergence speed with a slightly higher computational complexity only. Computer simulations show that the improved method also has a good performance in tracking the channel responses.