  The correlation of interference has been well quantified in Poisson networks
where the interferers are independent of each other. However, there exists
dependence among the base stations (BSs) in wireless networks. In view of this,
we quantify the interference correlation in non-Poisson networks where the
interferers are distributed as a Matern cluster process (MCP) and a
second-order cluster process (SOCP). Interestingly, it is found that the
correlation coefficient of interference for the Matern cluster networks,
$\zeta_{MCP}$, is equal to that for second-order cluster networks,
$\zeta_{SOCP}$. Furthermore, they are greater than their counterpart for the
Poisson networks. This shows that clustering in interferers enhances the
interference correlation. In addition, we show that the correlation
coefficients $\zeta_{MCP}$ and $\zeta_{SOCP}$ increase as the average number of
points in each cluster, $c$, grows, but decrease with the increase in the
cluster radius, $R$. More importantly, we point that the effects of clustering
on interference correlation can be neglected as
$\frac{c}{\pi^{2}R^{2}}\rightarrow0$. Finally, the analytical results are
validated by simulations.
