Estimation of Noise Parameters in Multi-Antenna Receivers using Digitized Signal Samples

Multi-antenna systems can provide multi-streaming and diversity operation even in the case where the antennas are spaced electrically close to each other. This requires that a decoupling and matching network (dmn) is connected between the antenna ports and the inputs of the low-noise amplifiers (lna) of the receiver. The job of the dmn is to electrically decouple the ports which are connected to the lnas, and to provide the latter with the optimum driving impedance such that their noise figure is minimum (noise matching). The value of the driving impedance to achieve noise matching only depends on certain noise parameters of the receiver. To our best knowledge, there is no measurement equipment available to this date, which would allow to measure these parameters. In this paper, we report on a simple scheme by which these noise parameters can be estimated using the multiantenna receiver itself as the measurement equipment. The idea is to connect the inputs of two lnas by a coax cable and estimate the correlation coefficient of the digitized outputs of the respective receiver chains. From two such estimated correlation coefficients obtained for two different lengths of the coax cable, all noise parameters which are relevant for noise matching can be obtained.