MMSE multi-user channel estimation for broadband wireless communications

This paper describes an MMSE multi-user frequency-domain channel identification algorithm for operation in a broadband wireless system such as OFDM. This algorithm tracks rapid channel variations both in frequency and in time, which is critical for antenna array processing algorithms attempting spatial division multiple access (SDMA) or multiple-input/multiple-output (MIMO) with high data rates over mobile radio channels. Various techniques for implementing the proposed algorithm are investigated as well as reduced complexity versions of the estimator. The performance of the channel estimation algorithm is evaluated by simulating its performance when it is used by optimal adaptive array combining algorithms operating in highly-selective mobile channels