  We propose a low-complexity variable forgetting factor (VFF) mechanism for
recursive least square (RLS) algorithms in interference suppression
applications. The proposed VFF mechanism employs an updated component related
to the time average of the error correlation to automatically adjust the
forgetting factor in order to ensure fast convergence and good tracking of the
interference and the channel. Convergence and tracking analyses are carried out
and analytical expressions for predicting the mean squared error of the
proposed adaptation technique are obtained. Simulation results for a
direct-sequence code-division multiple access (DS-CDMA) system are presented in
nonstationary environments and show that the proposed VFF mechanism achieves
superior performance to previously reported methods at a reduced complexity.
