Private Femtocells for Indoors

The Uplink interference management suite is focused on countering the impact of interference for femtocell deployment where both femtocells and macrocells operate on the same carrier. Due to closed subscriber groups, unplanned deployment without RF planning and low isolation between residences, femtocells can suffer from UL interference from macro users and can also cause unintended jamming effects on the uplink for the macrocells.

UltraSON™ Uplink Interference Management suite provides following features to effectively control uplink interference.

• Controlled Limit on UE Power (CLIP): This feature provides dynamic capping of femto mobile transmit power/data rate to limit uplink interference.
• Macro Aware Rise Setting (MARS): This feature enables the femto to set the noise-rise setting to protect the UL data rate performance of femto and macro mobiles.

The Femtocells R&D group conducted a comprehensive study on the impact 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 femtocell tolerance to both macro-to-femto and inter-femto interference while limiting femto-to-macro interference by setting the femtocell noise rise threshold (also called rise-over-thermal threshold) based on femto location within the associated macrocell.

These techniques also implement 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 established via thorough system-level simulations for both residential and enterprise femtocell deployments.