Investigation of MIMO channel correlation and capacity based on partial embedded RF measurements

In this paper, a technique for estimating the capacity and correlation of a MIMO channel is investigated by measuring complex signal ratios between receiver branches. The original channel matrix [H] is decomposed into a product of a diagonal matrix [D] and a matrix [G] of RF-measurable ratios of the H matrix elements. The RF measurements help provide partial channel estimation without computational overhead to the receiver. We present two RF measurement devices and discuss their implementation and interface to a MIMO receiver. Using Monte Carlo simulations, we show that the correlation properties of the original H matrix may be inferred from those of the G matrix thus leading to an indirect measurement of matrix channel correlation. Such information is very important for adaptive MIMO systems.