Minimizing inter-femtocell downlink interference
View Patent ↗A system and method for minimizing interference for mobile devices operating in a communication network that includes a centralized controller and a number of femtocells, each femtocell including a base station. The method calculates a power assignment priority for each femtocell, and determines a priority order of the femtocells, the priority order based on the power assignment priority calculated for each femtocell. The method calculates a power to assign to the base station for each femtocell based on the priority order. The method allocates a first portion of the power assigned to the base station for each femtocell as required for real-time traffic, and a second portion of the power assigned to the base station for each femtocell as required for non-real-time traffic.
1. A method for minimizing interference for mobile devices operating in a communication network that includes a centralized controller and at least one femtocell, each femtocell including a base station, the method comprising:
calculating a power assignment priority for each femtocell;
determining a priority order for said at least one femtocell, the priority order based on the power assignment priority calculated for each femtocell;
calculating a power to assign to the base station for each femtocell based on the priority order;
allocating a first portion of the power assigned to the base station for each femtocell as required for real-time traffic; and
allocating a second portion of the power assigned to the base station for each femtocell as required for non-real-time traffic.
2. The method of claim 1 , wherein the power assignment priority calculated for each femtocell includes a real-time traffic weighting factor, a non-real-time traffic weighting factor, a required power level, and an average power usage.
3. The method of claim 2 , wherein R i (n) is the power assignment priority for femtocell i in period n, and R i (n) is calculated as
R
i
(
n
)
=
λ
RT
,
i
(
n
)
λ
NRT
,
i
(
n
)
P
req
,
i
(
n
)
P
avg
,
i
(
n
)
,
wherein:
λ RT,i (n) is a real-time traffic weighting factor for femtocell i in period n,
λ NRT,i (n) is a non-real-time traffic weighting factor for femtocell i in period n,
P req,i (n) is a required power level for femtocell i in period n, and
P avg,i (n) is an average power usage for femtocell i in period n.
4. The method of claim 2 , wherein the required power level for each femtocell is approximated from a path loss of a mobile device in the communication network, a required Signal to Interference plus Noise Ratio (SINR), or an estimated interference.
5. The method of claim 1 , wherein the priority order is from a high priority femtocell to a low priority femtocell.
6. The method of claim 1 , wherein P i (n) is the power to assign to the base station for femtocell i in period n, and P i (n) is calculated as
P
i
(
n
)
=
min
(
(
∑
j
=
1
N
RT
,
i
(
n
)
S
I
N
R
RT
,
j
(
NF
+
I
)
PL
j
,
i
+
∑
j
=
1
N
NRT
,
i
(
n
)
S
I
N
R
NRT
,
j
(
NF
+
I
)
PL
j
,
i
)
,
P
max
,
P
i
,
allowed
)
,
wherein:
N RT,i (n) is a number of active real-time users in femtocell i in period n,
SINR RT is a required SINR of real-time users,
N NRT,i (n) is a number of active non-real-time users in femtocell i in period n,
SINR NRT is a required SINR of non-real-time users,
NF is a noise floor at each mobile device, the noise floor including thermal noise and noise figure,
PL j,i is a path loss from mobile device j to the base station for femtocell i,
P max is a maximum transmit power of the base station for one of said at least one femtocell,
P i,allowed is a transmit power allowed by those the base station for femtocells that have a higher power assignment priority higher than the base station for femtocell i, and
I is a received interference at the mobile devices associated with the base station for femtocell i from other neighboring femtocells.
7. The method of claim 6 , wherein P i,allowed is calculated as
P
i
,
allowed
=
min
∀
j
where
R
j
(
n
)
>
R
i
(
n
)
(
I
available
,
j
×
PL
BS_i
,
UE_j
)
,
wherein
:
I
available
,
j
=
I
-
∑
∀
k
where
R
k
(
n
)
>
R
j
(
n
)
P
k
(
n
)
×
PL
BS_k
,
UE_j
,
and
PL BS — i,UE — j is an average path loss between the base station for femtocell i and mobile device j.
8. A non-transitory computer-readable medium, comprising computer-executable instructions that, when executed on a computing device, perform the method of claim 1 .
9. A system for minimizing interference for mobile devices operating in a communication network that includes a centralized controller and at least one femtocell, each femtocell including a base station, comprising:
a memory device resident in the centralized controller; and
a processor disposed in communication with the memory device, the processor configured to:
calculate a power assignment priority for each femtocell;
determine a priority order for said at least one femtocell, the priority order based on the power assignment priority calculated for each femtocell;
calculate a power to assign to the base station for each femtocell based on the priority order;
allocate a first portion of the power assigned to the base station for each femtocell as required for real-time traffic; and
allocate a second portion of the power assigned to the base station for each femtocell as required for non-real-time traffic.
10. The system of claim 9 , wherein the power assignment priority calculated for each femtocell includes a real-time traffic weighting factor, a non-real-time traffic weighting factor, a required power level, and an average power usage.
11. The system of claim 10 , wherein R i (n) is the power assignment priority for femtocell i in period n, and R i (n) is calculated as
R
i
(
n
)
=
λ
RT
,
i
(
n
)
λ
NRT
,
i
(
n
)
P
req
,
i
(
n
)
P
avg
,
i
(
n
)
,
wherein:
λ RT,i (n) is a real-time traffic weighting factor for femtocell i in period n,
λ NRT,i (n) is a non-real-time traffic weighting factor for femtocell i in period n,
P req,i (n) is a required power level for femtocell i in period n, and
P avg,i (n) is an average power usage for femtocell i in period n.
12. The system of claim 10 , wherein the required power level for each femtocell is approximated from a path loss of a mobile device in the communication network, a required Signal to Interference plus Noise Ratio (SINR), or an estimated interference.
13. The system of claim 9 , wherein the priority order is from a high priority femtocell to a low priority femtocell.
14. The system of claim 9 , wherein P i (n) is the power to assign to the base station for femtocell i in period n, and P i (n) is calculated as
P
i
(
n
)
=
min
(
(
∑
j
=
1
N
RT
,
i
(
n
)
S
I
N
R
RT
,
j
(
NF
+
I
)
PL
j
,
i
+
∑
j
=
1
N
NRT
,
i
(
n
)
S
I
N
R
NRT
,
j
(
NF
+
I
)
PL
j
,
i
)
,
P
max
,
P
i
,
allowed
)
,
wherein:
N RT,i (n) is a number of active real-time users in femtocell i in period n,
SINR RT is a required SINR of real-time users,
N NRT,i (n) is a number of active non-real-time users in femtocell i in period n,
SINR NRT is a required SINR of non-real-time users,
NF is a noise floor at each mobile device, the noise floor including thermal noise and noise figure,
PL j,i is a path loss from mobile device j to the base station for femtocell i,
P max is a maximum transmit power of the base station for one of said at least one femtocell,
P i,allowed is a transmit power allowed by those the base station for femtocells that have a higher power assignment priority higher than the base station for femtocell i, and
I is a received interference at the mobile devices associated with the base station for femtocell i from other neighboring femtocells.
15. The system of claim 14 , wherein P i,allowed is calculated as
P
i
,
allowed
=
min
∀
j
where
R
j
(
n
)
>
R
i
(
n
)
(
I
available
,
j
×
PL
BS_i
,
UE_j
)
,
wherein
:
I
available
,
j
=
I
-
∑
∀
k
where
R
k
(
n
)
>
R
j
(
n
)
P
k
(
n
)
×
PL
BS_k
,
UE_j
,
and
PL BS — i,UE — j is an average path loss between the base station for femtocell i and mobile device j.
16. The method of claim 1 , wherein calculating a power assignment priority for each femtocell comprises calculating a power assignment priority corresponding to each femtocell based on real-time and non-real time traffic of the corresponding femto-cell.