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.

This paper proposes a cascade blockage model for analyzing the vision that a user has of a wireless network. This model, inspired by the classical multiplicative cascade models, has a radial structure meant to analyze blockages seen by the receiver at the origin in different angular sectors. The main novelty is that it is based on the geometry of obstacles and takes the joint blockage phenomenon into account. We show on a couple of simple instances that the Laplace transforms of total interference satisfies a functional equation that can be solved efficiently by an iterative scheme. This is used to analyze the coverage probability of the receiver and the effect of blockage correlation and penetration loss in both dense and sparse blockage environments. Furthermore, this model is used to investigate the effect of blockage correlation on user beamforming techniques. Another functional equation and its associated iterative algorithm are proposed to derive the coverage performance of the best beam selection in this context. In addition, the conditional coverage probability is also derived to evaluate the effect of beam switching. The results not only show that beam selection is quite efficient for multi-beam terminals, but also show how the correlation brought by blockages can be leveraged to accelerate beam sweeping and pairing.