Method and system for reducing co-channel interference due to the deployment of femtocells in a macro-cellular network

摘要

The present invention concerns a method and system for reducing co-channel interference due to the deployment of N femtocells in a macrocellular network. Said method comprises a step (1) of taking power measurements on signals sent over this network, a step (3) of optimizing the transmission powers of the femtocells according to these measurements, and a step (4) of allocating to each femtocell its transmission power. Said method is characterized in that:
during step (1) of taking measurements, the power measurements are only made by the N femtocells and these measurements are ordered temporally by a central facility UC in the system,during the optimization step (3), the transmission powers of the femtocells are maximized under the constraint of maintaining a minimum quality of service of terminals that would be attached to the base stations in the macrocellular network.

主权项

1. Method for reducing co-channel interference due to the deployment of N femtocells in a macrocellular network, N being an integer, said method comprising:
taking power measurements on signals sent over this network, during which the power measurements are only taken by the N femtocells and these measurements are ordered temporally by a central facility of the system, performing optimization of transmission powers of the femtocells according to the taken power measurements, and performing allocation, to the femtocells, of their respective optimized transmission power, wherein, during the optimisation of the transmission powers of the femtocells, the transmission powers of the femtocells are maximised under the constraint of maintaining a minimum quality of service of terminals that would be attached, in the macrocellular network, to base stations of the macrocellular network, wherein, during the optimisation of the transmission powers of the femtocells, the following cost function is maximised:maxPtn⁢c=∑n=1N⁢Ptnunder the following constraint:∀n∈{1,N},Ptn+∑m≠n⁢αn,mρ2⁢Ptm≤Prn,macroρ2⁢γMUEtarget-σn2≤Prn,macroρ2⁢γMUEtargetwhere Ptn is the emission power of a femtocell, referred to as FBSn, Ptm is the emission power of a femtocell, referred to as FBSm, cu is a weighting coefficient associated with the transmission power of the femtocell FBSn, αn,m is a coefficient of attenuation due to a channel separating the femtocell FBSm from the femtocell FBSn, Prn,macro is a power received by the femtocell FBSn from a signal that was sent by a base station in the macrocellular network considered to be dominant by the femtocell FBSn, σn2 is a power of surrounding thermal noise perceived by the femtocell FBSn, ρ is a coefficient that represents the coverage of the femtocell FBSn beyond which a terminal that would be attached to one of the base stations of the macrocellular network would see a signal to interference-plus-noise ratio greater than a threshold value γMUEtarget.