  In this paper, a novel $3$D cellular model consisting of aerial base stations
(aBSs) and aerial user equipments (aUEs) is proposed, by integrating the
coordinated multi-point (CoMP) transmission technique with the theory of
stochastic geometry. For this new $3$D architecture, a tractable model for
aBSs' deployment based on the binomial-Delaunay tetrahedralization is
developed, which ensures seamless coverage for a given space. In addition, a
versatile and practical frequency allocation scheme is designed to eliminate
the inter-cell interference effectively. Based on this model, performance
metrics including the achievable data rate and coverage probability are derived
for two types of aUEs: {\it i)} the general aUE (i.e., an aUE having distinct
distances from its serving aBSs) and {\it ii)} the worst-case aUE (i.e., an aUE
having equal distances from its serving aBSs). Simulation and numerical results
demonstrate that the proposed approach emphatically outperforms the
conventional binomial-Voronoi tessellation without CoMP. Insightfully, it
provides a similar performance to the binomial-Voronoi tessellation which
utilizes the conventional CoMP scheme; yet, introducing a considerably reduced
computational complexity and backhaul/signaling overhead.
