Co-channel operation of macro- and femtocells in a hierarchical cell structure

In this paper, the feasibility of user-deployed femtocells in the same frequency band as an existing macrocell network is investigated. Key requirements for co-channel operation of femtocells such as auto-configuration and public access are discussed. Methods for femtocell power auto-configuration that ensure a constant cell radius in the downlink, and a low pre-definable interference impact on co-channel macrocells in the uplink are proposed. The theoretical performance of randomly deployed femtocells in such a hierarchical cell structure and the resulting impact on existing co-channel macrocells is analysed for a cellular UMTS network using system level simulations.