Measurement-based stochastic models for the cross-correlation of multi-link small-scale fading in cooperative relay environments

In this contribution, stochastic models are established for the cross-correlation of the small-scale fading (SSF) in the impulse responses of two co-existing channels in cooperative relay scenarios based on measurement data collected using the wideband multiple-input multiple-output (MIMO) relay-Band-Exploration-and-Channel-Sounder (rBECS). The models extracted describe the variation of SSF cross-correlation coefficients with respect to geometrical variables in a three-node relay system, i.e. the angle between the direct link from the mobile station to the base station and that from the mobile station to the relay station, the average length of these two links, and the ratio between the length of the two links. It is observed that the parameters describing the distribution of the SSF cross-correlation coefficients can be modeled as analytical functions with respect to the aforementioned variables. These results are of importance for understanding the joint characteristics of co-existing wideband propagation channels in reality.