  Multi-cell cooperation is a promising approach for mitigating inter-cell
interference in dense cellular networks. Quantifying the performance of
multi-cell cooperation is challenging as it integrates physical-layer
techniques and network topologies. For tractability, existing work typically
relies on the over-simplified Wyner-type models. In this paper, we propose a
new stochastic-geometry model for a cellular network with multi-cell
cooperation, which accounts for practical factors including the irregular
locations of base stations (BSs) and the resultant path-losses. In particular,
the proposed network-topology model has three key features: i) the cells are
modeled using a Poisson random tessellation generated by Poisson distributed
BSs, ii) multi-antenna BSs are clustered using a hexagonal lattice and BSs in
the same cluster mitigate mutual interference by spatial interference
avoidance, iii) BSs near cluster edges access a different sub-channel from that
by other BSs, shielding cluster-edge mobiles from strong interference. Using
this model and assuming sparse scattering, we analyze the shapes of the outage
probabilities of mobiles served by cluster-interior BSs as the average number
$K$ of BSs per cluster increases. The outage probability of a mobile near a
cluster center is shown to be proportional to $e^{-c(2-\sqrt{\nu})^2K}$ where
$\nu$ is the fraction of BSs lying in the interior of clusters and $c$ is a
constant. Moreover, the outage probability of a typical mobile is proved to
scale proportionally with $e^{-c' (1-\sqrt{\nu})^2K}$ where $c'$ is a constant.
