What is spatial correlation?
Spatial correlation is relevant in sensor arrays and MIMO wireless communications. In the case of MIMO communications where multiple spatially separate antennas receive different observations of a multipath signal, spatial correlation can be used to evaluate the 'antennae diversity'. Higher the diversity, better the mitigation of signal fading effects introduced by the wireless medium. As a result the link quality is improved.
http://en.wikipedia.org/wiki/Antenna_diversity