Macrocell offloading benefits in joint macro-and femtocell deployments

Femtocells are low-cost, low-power cellular base stations that are designed to provide high quality cellular service in residential or enterprise environments and operate in licensed spectrum to connect conventional, unmodified mobile terminals to a mobile operator's network. The deployment of femtocells will reduce the number of indoor users that need to be served by the macrocellular network. Moreover, since indoor users usually have poorer radio channel conditions to the macrocell compared to outdoor users, for each indoor user that is served by a femtocell, the equivalent system resources of the macrocellular network might be able to serve more than one outdoor user, resulting in a potential macrocell offloading gain. The macrocell offloading benefits achievable in joint macro-femtocell deployments are investigated using system level simulations. It is shown that the potential increase in the number of supported users per macrocell in joint macro- and femtocell deployments depends on the macrocellular network configuration and can range from no gain for a system which is only interference limited to more than 30% in cases where noise is the limiting factor for indoor users at the macrocell edge.