Practical Correlation-Matrix Approaches for Standardized Testing of Wireless Devices in Reverberation Chambers

Abstract

We extend the autocorrelation-based approaches currently used in standards to full correlationmatrix-based approaches in order to identify correlation between both spatially adjacent and non-adjacent samples in reverberation-chamber measurements. We employ a scalar metric that allows users to identify the number of effectively uncorrelated samples in new types of stirring sequences. To make these approaches practical and enhance their accuracy, we implement a thresholding technique that retains correlation related to important aspects of chamber configuration such as loading and undermoded conditions. We develop a method to propagate uncertainty in the complex correlation coefficients through to the number of effective samples for a given reverberation-chamber set-up by use of a bootstrap technique that is accurate even for highly skewed distributions of correlation coefficients. We further apply this method in a sensitivity study regarding the choice of threshold value. Agreement with existing approaches in determining the number of effectively uncorrelated samples is presented for a measurement example where spatially adjacent samples are utilized. Examples are then illustrated for non-spatially-adjacent correlated samples at microwave and millimeter-wave frequencies.

A Practical Approach to Generating First-Order Rician Channel Statistics in a RC plus CATR Chamber at mmWave

“…The independence of the samples is relevant for several aspects of this work, including the GoF tests and the K−factor estimation. Following the discussion in [29], [30], the number of independent or effective samples N eff in the presence of more than one mode stirrer should be computed through the use of a circular-shift correlation matrix. The threshold used in [29], [30] for considering the correlation between samples is consistent with the one present in the standards [26], [31].…”

“…Following the discussion in [29], [30], the number of independent or effective samples N eff in the presence of more than one mode stirrer should be computed through the use of a circular-shift correlation matrix. The threshold used in [29], [30] for considering the correlation between samples is consistent with the one present in the standards [26], [31]. If fully satisfied, it ensures, with a 95% likelihood and for sample sizes larger than 100, that all samples are independent.…”

“…In the case of this work, there are two mode stirrers, although they move at the same time at equispaced steps. N eff is evaluated according to (3) from [29], where N = 600 are samples corresponding to unique positions of the mode stirrers and measured for each of the 526 FS.…”