Measurement of angular and distance correlation properties of log-normal shadowing at 1900 MHz and its application to design of PCS systems

This paper investigates the correlation properties of shadow fading as a function of the angle between two PCS base stations over urban, light urban, and suburban terrain. Results from this study are relevant to the analysis of interference, handoff gain, and to various frequency planning applications in modern cellular and PCS systems. Using a significantly larger data set than previous experiments, we observed that on the average, the shadow fading components of the signals are not correlated, even at small angles. Our results contradict the conventional wisdom, as expressed in several papers, which says that there is relatively high correlation at small angles. Our results indicate that a mathematically simpler uncorrelated model for the relationship between signals from multiple base stations at small angles can be used in analysis tools. Distance correlation measurements computed by forming the autocorrelation function on a large number of data sets showed that the correlation distance of the shadowing process ranges from about 25 to 100 m.