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On the Statistics of the IEEE 802.11n/ac Fading Channel Models

In this letter, we present closed-form expressions for the complex autocorrelation function (ACF) and for the envelope level crossing rate (LCR) and average fade duration (AFD) parameters pertaining to the fading channel models proposed in the IEEE 802.11n/ac standards, which specify a bell-shaped Doppler power spectral density (PSD), truncated to a maximum cutoff frequency fmax. It is shown that the ACF is not very sensitive to fmax and that the dependence of the LCR and AFD on this parameter may be exploited to ease the implementation of practical channel simulators for this standard. A new series expansion for the LCR of general Rice-distributed envelopes, which avoids numerical integration, together with a useful upper bound on the precision of the truncated series is also presented.