  Femtocells represent a promising alternative solution for high quality
wireless access in indoor scenarios where conventional cellular system coverage
can be poor. Femtocell access points (FAP) are normally randomly deployed by
the end user, so only post deployment network planning is possible.
Furthermore, this uncoordinated deployment creates the potential for severe
interference to co-located femtocells, especially in dense deployments. This
paper presents a new femtocell network architecture using a generalized virtual
cluster femtocell (GVCF) paradigm, which groups together FAP, which are
allocated to the same femtocell gateway (FGW), into logical clusters. This
guarantees severely interfering and overlapping femtocells are assigned to
different clusters, and since each cluster operates on a different band of
frequencies, the corresponding virtual cluster controller only has to manage
its own FAP members, so the overall system complexity is low. The performance
of the GVCF algorithm is analysed from both a resource availability and cluster
number perspective, and a novel strategy is proposed for dynamically adapting
these to network environment changes, while upholding quality-of-service
requirements. Simulation results conclusively corroborate the superior
performance of the GVCF model in interference mitigation, particularly in high
density FAP scenarios.
