Managing interference from femtocells

1. A method for minimizing interference for mobile devices operating in a communication network that includes a macrocell base station and at least one femtocell, each femtocell including a base station, the method comprising:

receiving, by the at least one femtocell base station, initialization data on a backhaul connection that connects the at least one femtocell base station and the macrocell base station;

configuring, by the at least one femtocell base station, the femtocell base station transmitting power of the at least one femtocell base station based on the initialization data;

receiving a user equipment identifier from a macrocell user equipment in the communication network;

validating the user equipment identifier to determine whether the macrocell user equipment is authorized or unauthorized;

when the macrocell user equipment is authorized to access the femtocell base station,

granting the macrocell user equipment access to the at least one femtocell base station;

when the macrocell user equipment is unauthorized to access the femtocell base station,

receiving user equipment information on the backhaul connection, wherein the user equipment information describes the macrocell user equipment; and

adjusting, by the at least one femtocell base station, the femtocell base station transmitting power of the at least one femtocell base station based on the user equipment information to minimize the interference for mobile devices in the communications network.

2. The method of claim 1 , wherein the receiving of the initialization data further comprises:

sending an initialization call to the macrocell base station,

wherein a femtocell user equipment associated with the al least one femtocell base station sends the initialization call, and

wherein the initialization data is calculated from based on transmission characteristics of the initialization call.

3. The method of claim 2 , wherein the transmission characteristics include path loss and interference level at the femtocell user equipment.

4. The method of claim 1 , wherein the user equipment identifier is an International Mobile Subscriber Identify (IMSI) associated with the macrocell user equipment.

5. The method of claim 1 , wherein the validating of the user equipment identifier further comprises:

comparing the user equipment identifier to an access control list,

wherein when the access control list includes an entry that matches the user equipment identifier, the macrocell user equipment is authorized, otherwise the macrocell user equipment is unauthorized.

6. The method of claim 1 , wherein when the femtocell is based on Orthogonal Frequency-Division Multiple Access technology, the adjusting of the femtocell base station transmitting power further comprises:

receiving subcarrier assignments for the macrocell user equipment; and

decreasing the femtocell base station transmitting power for the subcarrier assignments for the macrocell user equipment.

7. The method of claim 1 , wherein when the femtocell is based on Universal Mobile Telecommunication System technology, the adjusting of the femtocell base station transmitting power further comprises:

receiving a target signal-to-noise ratio, measured signal-to-noise ratio, and received power for the macrocell user equipment;

adjusting the femtocell base station transmitting power for a number N of macrocell user equipments, including the macrocell user equipment, as

P

margin

,

i

=

(

P

r

,

i

S

⁢

⁢

N

⁢

⁢

R

target

,

i

-

P

r

,

i

S

⁢

⁢

N

⁢

⁢

R

measured

,

i

)

,

wherein:

P margin,i , is an interference power that macrocell user equipment i can tolerate, for iε {1 . . . N},

P r,i is the received power for the macrocell user equipment i,

SNR target,i is the target signal-to-noise ratio for macrocell user equipment i, and

SNR measured,i is the measured signal-to-noise ratio for macrocell user equipment i.

8. The method of claim 7 , wherein when the at least one femtocell base station is in a building and the macrocell user equipment is outside the building, the femtocell base station transmitting power is calculated as

P

Femto

=

min

i

=

1

⁢

⁢

…

⁢

⁢

N

⁢

(

P

margin

,

i

)

+

P

L

,

wherein:

P Femto is a total transmitting power for the at least one femtocell base station, and

P L is a minimum path loss from the at least one femtocell base station to the macrocell user equipment.

9. A non-transitory computer-readable medium, comprising computer-executable instructions that, when executed on a computer device, perform the method of claim 1 .

10. A system for minimizing interference for mobile devices operating in a communication network that includes a macrocell base station and at least one femtocell, each femtocell including a base station, comprising:

a memory device resident in the at least one femtocell base station; and

a processor disposed in communication with the memory device, the processor configured to:

receive, by the at least one femtocell base station, initialization data on a backhaul connection that connects the at least one femtocell base station and the macrocell base station;

configure, by the at least one femtocell base station, the femtocell base station transmitting power of the at least one femtocell base station based on the initialization data;

receive a user equipment identifier from a macrocell user equipment in the communication network;

validate the user equipment identifier to determine whether the macrocell user equipment is authorized or unauthorized;

when the macrocell user equipment is authorized to access the femtocell base station,

grant the macrocell user equipment access to the at least one femtocell base station;

when the macrocell user equipment is unauthorized to access the femtocell base station,

receive user equipment information on the backhaul connection, wherein the user equipment information describes the macrocell user equipment; and

adjust, by the at least one femtocell base station, the femtocell base station transmitting power of the at least one femtocell base station based on the user equipment information to minimize the interference for mobile devices in the communications network.

11. The system of claim 10 , wherein to receive the initialization data the processor is further configured to:

send an initialization call to the macrocell base station,

wherein a femtocell user equipment associated with the at least one femtocell base station sends the initialization call, and

wherein the initialization data is calculated from based on transmission characteristics of the initialization call.

12. The system of claim 11 , wherein the transmission characteristics include path loss and interference level at the femtocell user equipment.

13. The system of claim 10 , wherein the user equipment identifier is an International Mobile Subscriber Identify (IMSI) associated with the macrocell user equipment.

14. The system of claim 10 , wherein to validate the user equipment identifier the processor is further configured to:

compare the user equipment identifier to an access control list,

wherein when the access control list includes an entry that matches the user equipment identifier, the macrocell user equipment is authorized, otherwise the macrocell user equipment is unauthorized.

15. The system of claim 10 , wherein when the femtocell is based on Orthogonal Frequency-Division Multiple Access technology, to adjust the femtocell base station transmitting power the processor is further configured to:

receive subcarrier assignments for the macrocell user equipment; and

decrease the femtocell base station transmitting power for the subcarrier assignments for the macrocell user equipment.

16. The system of claim 10 , wherein when the femtocell is based on Universal Mobile Telecommunication System technology, to adjust the femtocell base station transmitting power the processor is further configured to:

receiving a target signal-to-noise ratio, measured signal-to-noise ratio, and received power for the macrocell user equipment;

adjusting the femtocell base station transmitting power for a number N of macrocell user equipments, including the macrocell user equipment, as

P

margin

,

i

=

(

P

r

,

i

S

⁢

⁢

N

⁢

⁢

R

target

,

i

-

P

r

,

i

S

⁢

⁢

N

⁢

⁢

R

measured

,

i

)

,

wherein:

P margin,i is an interference power that macrocell user equipment i can tolerate, for iε {1 . . . N},

P r,i is the received power for the macrocell user equipment i,

SNR target,i is the target signal-to-noise ratio for macrocell user equipment i, and

SNR measured, i is the measured signal-to-noise ratio for macrocell user equipment i.

17. The system of claim 16 , wherein when the at least one femtocell base station is in a building and the macrocell user equipment is outside the building, the femtocell base station transmitting power is calculated as

P

Femto

=

min

i

=

1

⁢

⁢

…

⁢

⁢

N

⁢

(

P

margin

,

i

)

+

P

L

,

wherein:

P Femto is a total transmitting power for the femtocell base station, and

P L is a minimum path loss from the at least one femtocell base station to the macrocell user equipment.