On Modeling Multi-Antenna Multipath Channels

Accurate and tractable channel modeling is critical to realizing the full potential of antenna arrays in wireless communications. In this paper we propose a framework for modeling multi-antenna multipath channels based on the notion of virtual spatial angles. The virtual angles are xed a priori and are determined by the number of antennas at the transmitter and receiver and the spacing between the antennas. The model essentially corresponds to a coordinate transformation via xed spatial basis functions (array response and steering vectors) at the transmitter and receiver. The resulting linear channel matrix representation in the virtual space encompasses all existing models and provides a natural link between the actual physical propagation environment and the channel statistics induced by it. For any given scattering environment, the model clearly reveals the two key parameters aaecting channel capacity: the number of parallel channels and the level of diversity associated with each parallel channel. In addition to facilitating realistic estimates of channel capacity, the virtual space framework also suggests low-complexity channel approximations that may be leveraged in eecient transceiver design.