Adaptive Subcarrier Grouping for MMSE-SMI Adaptive Array Interference Suppression

Inter-user interference (IUI) suppression is a prime matter for mobile communication systems. Channel state information (CSI), meanwhile, is severely affected by the receiver additive noise effect. Sample matrix inversion (SMI) based minimum mean square error (MMSE) adaptive array is a powerful means to suppress noise enhancement with the aid of data symbols. However, its effectiveness is limited under an insufficient number of symbols available. Based on the multi-carrier transmission system, this paper proposes an adaptive subcarrier grouping to expand the number of received symbols for a covariance matrix calculation. The grouping size is adaptively adjusted by observing the dispersion of adjacent subcarriers. Simulative results reveal the effectiveness of the proposed adaptive algorithm; superior bit error rate (BER) performance can be attained under various Rician $K$ factors.