  We introduce a comprehensive analytical framework to compare between open
access and closed access in two-tier femtocell networks, with regard to uplink
interference and outage. Interference at both the macrocell and femtocell
levels is considered. A stochastic geometric approach is employed as the basis
for our analysis. We further derive sufficient conditions for open access and
closed access to outperform each other in terms of the outage probability,
leading to closed-form expressions to upper and lower bound the difference in
the targeted received power between the two access modes. Simulations are
conducted to validate the accuracy of the analytical model and the correctness
of the bounds.
