Deployment Options for Femtocells and their Impact on Existing Macrocellular Networks

Femtocells can enable in-home cell phone coverage and provide access to high speed wireless broadband services where the usual macrocell system can only provide degraded service indoors or provides no coverage at all. In this paper different frequency deployment and access strategies for femtocells are explored, and their impact on the performance of both the femtocells and existing macrocellular networks is investigated. Options such as shared, partially shared, and separate carrier deployments with private and public access are discussed. For shared carrier operation, the impact on the coverage, blocking probabilities, and capacity is investigated based on scenario data from real deployments using the Alcatel-Lucent Ocelot coverage engine, which includes sophisticated models for various wireless technologies including UMTS and HSDPA. It is shown that co-channel operation of femto- and macrocells is feasible without causing coverage problems due to the increased interference when public access is allowed. For private access, co-channel operation results in dead zones and reduced coverage probability in proximity of femtocells for mobiles without access. This problem can be resolved by using partially shared carriers with a "clean" macrocell carrier for affected mobiles, or a separate carrier deployment.