Load balancing in open access femtocell based two-tier cellular networks

Femtocell base station (BS) is a low-power, low-price BS based on cellular communication technology. It is expected to become a cost-effective solution for improving the communication performance of indoor users, whose traffic demands are large in general. There are mainly two access strategies for femtocell, i.e., closed and open access strategies. While it has been known that open access femtocells contribute more to enhancing the system-wide performance than closed access femtocells, the performance of open access femtocell owners can be potentially degraded when sharing their BSs with other macrocell users. To prevent this potential problem, we develop a load balancing scheme which maximizes the average throughput of macrocell users while guaranteeing some degree of benefits to femtocell owners. To achieve this goal, we jointly optimize the ratio of dedicated resources for femtocells as well as the femtocell service area via an analytic model, which proves that the optimization is a convex optimization problem in the typical environments. Our analysis and simulation results show that the proposed load balancing scheme significantly enhances the system-wide performance.