Method for distributed interference coordination in a femtocell environment

1. A method of improving distributed inter-cell interference in a communication system including at least a first femtocell system and one or more other femtocell systems, the method comprising:

obtaining by the first femtocell system a reference signal received power (RSRP) from one or more other femtocell systems;

obtaining a fading matrix F at the first femtocell system of fading values between the first femtocell system and the one or more other femtocell systems based on the RSRP;

determining an interference correlative matrix D at the first femtocell system corresponding to the fading matrix F relative to a predetermined threshold value Γ T ; and

estimating an influence of a use of a resource on the communications system at the first femtocell system based at least partially on the interference correlative matrix D.

2. The method of claim 1 , further comprising recording information related to the fading matrix F and interference correlative matrix D at one or more of the first femtocell system and the one or more other femtocell systems.

3. The method of claim 1 , wherein estimating an influence of a use of a resource on the communications system comprises estimating a throughput T 0 k of the first femtocell system which can be obtained on a carrier wave k.

4. The method of claim 3 , wherein estimating an influence of a use of a resource on the communications system further comprises:

using the interference correlative matrix D to identify a second femtocell system with strongest interference with the first femtocell system and a carrier wave k1 with the strongest interference between the first femtocell system and the second femtocell system,

wherein if not T 0 k <Γ T , where Γ T corresponds to the predetermined threshold value, the first femtocell system negotiates with the second femtocell system about using a carrier wave k2, which is at least substantially orthogonal to the carrier wave k1,

wherein if T 0 k <Γ T , the first femtocell system negotiates with the second femtocell system about using the carrier wave k1.

5. The method of claim 4 , wherein estimating an influence of a use of a resource on the communications system further comprises:

determining which carrier waves of the first femtocell system are being used by the first femtocell system;

for each of the carrier waves being used by the first femtocell system, the first femtocell system calculates the throughput T 0 k of the carrier wave k corresponding to what the decrement of the throughput will be on the first femtocell system if the first femtocell system discards the carrier wave k; and

estimating an increment of throughput ΔT i of Femtocell i , after the first femtocell system discards the carrier wave k, where i corresponds to one or more other femtocell i systems in a set I of the one or more other femtocell systems where fading value is less than the predetermined threshold value Γ T .

6. The method of claim 5 ,

wherein estimating an increment of throughput ΔT i of femtocell i , after the first femtocell system discards the carrier wave k comprises approximating an interference I i of each of the other femtocell i systems in the set I as being equal to an interference I 0 of the first femtocell system.

7. The method of claim 6 , wherein estimating an influence of a use of a resource on the communications system further comprises:

for each of the carrier waves not being used by the first femtocell system, calculating the throughput T 0 k of the carrier wave k corresponding to the increment of the throughput ΔT i on the communication system when the first femtocell system uses the carrier wave k; and

estimating an increment of throughput ΔT i of femtocell i , after the first femtocell system discards the carrier wave k, where i corresponds to each of the at least one other femtocell systems in a set I of the other femtocell systems where fading value is less than the predetermined threshold value Γ T .

8. The method of claim 5 , further comprising determining at the first femtocell whether to use the resource wherein determining at the first femtocell whether to use the resource comprises:

discarding the carrier wave k at the first femtocell system if T 0 k and ΔT i satisfy Equation (1):

T 0 k >Σ iεI ΔT i ; or  (1)

continuing to use the carrier wave k if T 0 k and ΔT i do not satisfy the Equation (1).

9. The method of claim 8 , wherein determining at the first femtocell whether to use the resource further comprises:

using the carrier wave at the first femtocell system if T 0 k and ΔT i satisfy Equation (5):

Δ

⁢

⁢

T

i

T

i

<

T

0

k

T

0

×



I

0



(

5

)

where |I 0 | is the number of elements in the set I of the other femtocell systems where fading value is less than the predetermined threshold value; or

not using the carrier wave k if T 0 k and ΔT i do not satisfy the Equation (5).

10. The method of claim 9 ,

wherein estimating an increment of throughput ΔT i of femtocell i , after the first femtocell system discards the carrier wave k comprises approximating an interference I i of each of the other femtocell i systems in the set I as being equal to an interference I 0 of the first femtocell system.

11. A first femtocell system configured to be included in a communications system with one or more other femtocell systems, the first femtocell system configured to perform operations for improving distributed inter-cell interference in the communication system, the operations comprising:

obtaining a reference signal received power (RSRP) from one or more other femtocell systems;

obtaining a fading matrix F at the first femtocell system of fading values between the first femtocell system and the one or more other femtocell systems based on the RSRP;

determining an interference correlative matrix D at the first femtocell system corresponding to the fading matrix F relative to a predetermined threshold value Γ T ; and

estimating an influence of a use of a resource on the communications system at the first femtocell system based at least partially on the interference correlative matrix D.

12. The first femtocell system of claim 11 , wherein the first femtocell system is further configured to record information related to the fading matrix F and interference correlative matrix D.

13. The first femtocell system of claim 11 , wherein estimating an influence of a use of a resource on the communications system comprises estimating a throughput T 0 k of the first femtocell system which can be obtained on a carrier wave k.

14. The first femtocell system of claim 13 , wherein estimating an influence of a use of a resource on the communications system further comprises:

using the interference correlative matrix D to identify a second femtocell system with strongest interference with the first femtocell system and a carrier wave k1 with the strongest interference between the first femtocell system and the second femtocell system,

wherein if not T 0 k <Γ T , where Γ T corresponds to the predetermined threshold value, the first femtocell system negotiates with the second femtocell system about using a carrier wave k2, which is at least substantially orthogonal to the carrier wave k1,

wherein if T 0 k <Γ T , the first femtocell system negotiates with the second femtocell system about using the carrier wave k1.

15. The first femtocell system of claim 14 , wherein estimating an influence of a use of a resource on the communications system further comprises:

determining which carrier waves of the first femtocell system are being used by the first femtocell system;

for each of the carrier waves being used by the first femtocell system, the first femtocell system calculates the throughput T 0 k of the carrier wave k corresponding to what the decrement of the throughput will be on the first femtocell system if the first femtocell system discards the carrier wave k; and

estimating an increment of throughput ΔT i of Femtocell i , after the first femtocell system discards the carrier wave k, where i corresponds to one or more other femtocell i systems in a set I of the one or more other femtocell systems where fading value is less than the predetermined threshold value Γ T .

16. The first femtocell system of claim 15 , wherein:

estimating an increment of throughput ΔT i of femtocell i , after the first femtocell system discards the carrier wave k comprises approximating an interference I i of each of the other femtocell i systems in the set I as being equal to an interference I 0 of the first femtocell system.

17. The first femtocell system of claim 16 , wherein estimating an influence of a use of a resource on the communications system further comprises:

for each of the carrier waves not being used by the first femtocell system, calculating the throughput T 0 k of the carrier wave k corresponding to the increment of the throughput ΔT i on the communication system when the first femtocell system uses the carrier wave k; and

estimating an increment of throughput ΔT i of femtocell i , after the first femtocell system discards the carrier wave k, where i corresponds to each of the at least one other femtocell systems in a set I of the other femtocell systems where fading value is less than the predetermined threshold value Γ T .

18. The first femtocell system of claim 15 , wherein:

the operations further comprise determining at the first femtocell whether to use the resource, and

determining at the first femtocell whether to use the resource comprises:

discarding the carrier wave k at the first femtocell system if T 0 k and ΔT i satisfy Equation (1):

T 0 k >Σ iεI ΔT i ; or  (1)

continuing to use the carrier wave k if T 0 k and ΔT i do not satisfy the Equation (1).

19. The first femtocell system of claim 18 , wherein the determining at the first femtocell whether to use the resource further comprises:

using the carrier wave at the first femtocell system if and ΔT i satisfy Equation (5):

Δ

⁢

⁢

T

i

T

i

<

T

0

k

T

0

×



I

0



(

5

)

where |I 0 | is the number of elements in the set I of the other femtocell systems where fading value is less than the predetermined threshold value; or

not using the carrier wave k if T 0 k and ΔT i do not satisfy the Equation (5).

20. The first femtocell system of claim 19 , wherein:

estimating an increment of throughput ΔT i of femtocell i , after the first femtocell system discards the carrier wave k comprises approximating an interference I i of each of the other femtocell i systems in the set I as being equal to an interference I 0 of the first femtocell system.