On the Suitable Environments of the Kronecker Product Form in MIMO Channel Modeling

Recent Multi-Input-Multi-Output research demonstrates that real wireless environments exhibit spatially correlated fadings: The independent fading assumption does not hold in all cases. Accordingly, spatially correlated MIMO channel models have attracted much attention. The Kronecker product form (KPF) is the currently most widely used MIMO channel model describing spatial correlations. However, its validity in various environments have not been well examined. In this work, first the correlation structure of the KPF is discussed. It is shown that the KPF exhibits a separable correlation structure. Second, it is claimed that the separable correlation structure corresponds to separable scatterers in physical environment. Using this utility, the KPF is examined with two popular scatterer distributions: two ring models and elliptic models. It is shown that the KPF is feasible for describing two ring models, but not capable of describing elliptic models. Numerical ray-tracing simulations verify the theoretical results.