Joint spatial and temporal characterization of the wideband wireless communication channel for MIMO applications

We present a joint study of the spatial and temporal behavior of the wideband wireless channel focussed on the possibility of applying multiple-input multiple-output (MIMO) techniques for achieving extremely high data rates. In particular, we address the time dependence of small-scale spatial variations in the transmitted field resulting from pulse propagation, which could be crucial for such applications. We have performed measurements of the field associated with the propagation of a pulse in a strongly scattering environment over a local area of several wavelengths at slightly different positions of the radiation source, which allowed us to simulate the performance of a multiple-antenna system over a wideband wireless channel. From the data obtained we are able to estimate the "instantaneous" achievable capacity of multiple-antenna systems, which is found to rise to within 5% of the upper theoretical bound. The results obtained for the capacity of wideband MIMO systems are in accord with the observed behavior of the field temporal and spatial autocorrelation functions.