A MIMO Mobile-To-Mobile Channel Model: Part I - The Reference Model

In this paper, we propose a multiple-input multiple-output (MIMO) channel model for mobile-to-mobile communications. This so-called MIMO mobile-to-mobile channel model is derived from the geometrical two-ring scattering model under the assumption that both the transmitter and the receiver are moving. In Part I of our paper, we focus on the reference model, which is based on the assumption that the transmitter and the receiver are surrounded by an infinite number of local scatterers. From a wave model, the complex channel gains are derived and their statistical properties are studied. General analytical solutions are provided for the three-dimensional (3-D) space-time cross-correlation function (CCF). We show that this 3-D function can be expressed as the product of two 2-D space-time CCFs, which are introduced as the transmit and receive CCF. Especially for the latter CCFs, closed-form expressions and numerical results are presented in case of isotropic scattering. The procedure presented in our paper provides an important framework for designers of future mobile-to-mobile communication systems to verify new transmission concepts under certain propagation conditions