1 The Signal Dimensions in Multiple-Antenna Channels

Abstract — 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 avaliable signal space in wireless channels. I