Keyhole effects in MIMO wireless channels - measurements and theory

In English It has been predicted theoretically that for some environments, the capacity of wireless MIMO systems can become very low, even for uncorrelated signals; this effect has been termed "keyhole" or "pinhole". We present the first unique measurements of this effect. The measurements were performed in a controlled indoor environment that was designed to obtain a keyhole. We analyze the limitations for measurement-based capacity calculations and keyhole investigations. We further present error bounds for the capacity and eigenvalue distributions due to measurement imperfections, such as finite signal-to-noise ratio and multipath leakage. The bounds are compared to the measurement results and show excellent agreement. Finally, we analyze the envelope distribution and find that, as expected from theory, it follows a double Rayleigh