Characterizing outage capacity for space-time communication over wideband wireless channels

We provide a compact characterization of the outage rates for wideband wireless communication, quantifying the effects of frequency and spatial diversity. Our information-theoretic computations yield the following findings. (a) Complex models typically employed in simulations can be replaced by simple, bandwidth-dependent, tap delay line models without loss of generality. (b) The spectral efficiency (i.e., the achievable rate, divided by the bandwidth) is well approximated as a Gaussian random variable, so that it is only necessary to specify its mean and variance to obtain outage rates. (c) The mean spectral efficiency depends only on the spatial diversity, while the variance depends on the spatial and frequency diversity via a product. Our definitions of frequency and spatial diversity have physically motivated interpretations, and are not based on high signal-to-noise ratio (SNR) asymptotics as in prior work.