The Small Cells R&D group conducted a comprehensive study on the impact of femto-to-macro, macro-to-femto and inter-femto uplink interference scenarios. The proposed UL interference management techniques are based on a distributed implementation that does not require modifications to the existing 3G macro network. These innovations are targeted to maximize the small cell tolerance to both macro-to-femto and inter-femto interference while limiting femto-to-macro interference by setting the small cell noise rise threshold (also called rise-over-thermal threshold) based on the femto location within the associated macrocell.
These techniques also implement a tight control of the femto-to-macro interference by limiting the femto user transmit power/rate dynamically based on path loss to the macrocell. The effectiveness of the algorithms has been demonstrated via through system-level simulations for both residential and enterprise small cell deployments.