The signal dimensions in multiple-antenna channels

This paper develops a physical channel model for multiple-antenna systems. The model appropriately abstracts the scattering intensity of physical environments, geometry of antenna arrays and degrees of polarization. Then, we use the model to demonstrate that the "space" in wireless systems is composed of three signal dimensions: wavevector, array and polarization. The impact of physical environment, array geometry and polarization are captured separately in the wavevector, array and polarization dimensions respectively. Thus, we solidify the "space" dimensions in complement to the time and frequency dimensions, and unify the available signal space in wireless channels.