MIMO signal description for spatial-variant filter generation

Channel modelling today has to address time-variant systems with multiple antennas at the transmitter and at the receiver, the so-called MIMO (multiple input multiple output) systems. In order to describe this time-variant channel with spatially distributed antennas by a simple space-time filter, spatial system functions are defined, which are based on a space-time analogy of Bello\´s (1963) "physical-intuitive" systems functions. In addition, the paper in hand considers space-time correlation functions and introduces the corresponding space-time filter approach.