Macro-Diversity in Cellular Networks With Correlated Blockage Model

Blockage effects can dramatically deteriorate high frequency cellular network performance. One practical solution is to apply macro-diversity technique, where the user associates with more than one Base Station (BS), to improve the chance of Light-Of-Sight (LOS) link availability. However, how the correlations are brought by both blockages and cooperative BSs is still unclear due to the analytical complexity. In addition, these two kinds of correlations are highly coupled and further impact macro-diversity gain. On basis of the cascade blockage model, this paper proposes a new functional framework to evaluate macro-diversity gains from the perspective of a typical user subjected to three metrics: joint LOS probability, conditional LOS probability and coverage probability. We first derive a set of tractable functional equations to describe three performance metrics. Then corresponding iterative algorithms that can be solved efficiently are designed respectively for three metrics. This analytical framework gains insight into contradictory requirements for macro-diversity, which not only guide the usage of Coordinated MultiPoint (CoMP) in realistic environments, but also determine the beamforming usage in mmWave band. We demonstrate the feasibility and flexibility of this functional framework by a simplified joint transmission example.