Method and controller for allocating whitespace spectrum
View Patent ↗Disclosed is a method and apparatus for allocating a set of frequency bands to a plurality of access points. The method includes generating an interference map associated with the set of frequency bands and associated with the plurality of access points. The method includes aggregating a plurality of demands to produce an aggregate demand. Each of the plurality of demands associated with one of the plurality of access points. The method includes dynamically allocating the set of frequency bands to each of the plurality of access points based on the interference map and the aggregate demand.
1. A controller comprising:
a first module configured to generate an interference map associated with a set of frequency bands and associated with a plurality of access points;
a second module configured to aggregate a plurality of demands to produce an aggregate demand, each of the plurality of demands associated with one of the plurality of access points;
a third module configured to dynamically allocate the set of frequency bands to each of the plurality of access points based on the interference map and the aggregate demand.
2. The controller of claim 1 , wherein
the first module is configured to receive an ambient interference value associated with a first frequency from each of the access points,
the first module is configured to calculate a plurality of interference values for each of the access points, each of the interference values being calculated at a plurality of second frequencies based on the received ambient interference value, and
the first module is configured to generate the interference map based on an available spectrum band, the received ambient interference values, and the calculated interference values.
3. The controller of claim 2 , wherein the first module is configured to receive the ambient interference values from the access points via a control channel.
4. The controller of claim 2 , wherein, in the absence of ambient interference, the first module calculates each of the calculated interference values such that,
Pr ( f 1)− Pr ( f 2)=10 coeff log 10 ( f 2 /f 1), where
f1 is the first frequency;
f2 is one of the plurality of second frequencies;
Pr(f1) is the calculated interference value at the first frequency received from one of the access points;
Pr(f2) is a calculated interference value at one of the plurality of second frequencies f2; and
coeff is an environment dependent parameter obtained through measurements.
5. The controller of claim 1 , wherein
the second module is configured to receive an average interference value from each of the access points;
the second module is configured to receive a first aggregate spectral efficiency value associated with a first frequency from each of the access points;
the second module is configured to calculate a plurality of second aggregate spectral efficiency values associated with a plurality of second frequencies for each of the access points; and
the second module aggregates the plurality of demands to produce an aggregate demand based on the first aggregate spectral efficiency value and the second aggregate spectral efficiency values.
6. The controller of claim 5 , wherein
the first frequency is the lowest frequency in a band of the set of frequency bands; and
the first aggregate spectral efficiency value for each access point is based on,
A
S
E
(
f
1
)
=
a
+
b
N
∑
k
=
1
N
SINR
k
(
f
1
)
,
where
ASE(f1) is the aggregate spectral efficiency value associated with the first frequency;
a and b are constants;
N is a number users;
k is the user for which the ASE is being calculated; and
SINR is a Signal to Interference-plus-Noise Ratio.
7. The controller of claim 5 , wherein
the second module calculates the second aggregate spectral efficiency values for each access point such that,
ASE( f 1)−ASE( f 2)=10 coeff log 10 ( f 2 /f 1), where
f1 is the first frequency;
f2 is one of the second frequencies;
coeff is an environment dependent parameter obtained through measurements;
ASE(f1) is the first aggregate spectral efficiency value received from one of the access points; and
ASE(f2) is the calculated second aggregate spectral efficiency value at the second frequency f2 for the access point.
8. The controller of claim 1 , wherein
the controller is configured to determine if the access points include two or more radio transmitters each capable of transmitting signals over a plurality of frequencies,
the controller is configured to identify groups of access points neighboring each of the access points, and the third module is configured to allocate the set of frequency bands based on prioritizing the groups of access points, the interference map and the aggregate demand if the access points do not include two or more radio transmitters, and
the third module is configured to allocate sub-bands of at least one of the frequency bands based on a utilization of the sub-bands, the interference map and the aggregate demand if the access points include two or more radio transmitters.
9. The controller of claim 8 , wherein
the third module is configured to calculate utilization of the sub-bands based on a utility calculation for each of the access points and configured to calculate a maximum utilization improvement based on a utilization of each of the set of frequency bands, and
the third module is configured to allocate the sub-bands based on the utilization improvement.
10. The controller of claim 8 , wherein the third module is configured to allocate the set of frequency bands based on a guard band associated with adjacent frequency bands, a transmit power constraint and a demand of one or more users associated with each of the access points.
11. A method for allocating a set of frequency bands to a plurality of access points, the method comprising:
generating, by a controller, an interference map associated with the set of frequency bands and associated with the plurality of access points;
aggregating a plurality of demands to produce an aggregate demand, each of the plurality of demands associated with one of the plurality of access points; and
dynamically allocating, by the controller, the set of frequency bands to each of the plurality of access points based on the interference map and the aggregate demand.
12. The method of claim 11 , comprising:
receiving, by the controller, a signal strength indicator from each of the access points;
determining, by the controller, an access point neighbor relationship for each of the access points;
receiving, by the controller, the plurality of demands based on one or more users associated with each of the access points; and
sending the allocated set of frequency bands to each of the plurality of access points.
13. The method of claim 11 , comprising:
receiving, by the controller, an ambient interference value associated with a first frequency from each of the access points; and
calculating, by the controller, a plurality of interference values for each of the access points, each of the interference values being calculated at a plurality of second frequencies based on the received ambient interference value, wherein
the interference map is generated based on an available spectrum band, the received ambient interference values, and the calculated interference values.
14. The method of claim 13 , wherein
the ambient interference values are received from the access points via a control channel.
15. The method of claim 13 , wherein, in the absence of ambient interference, each of the calculated interference values are calculated such that,
Pr ( f 1)− Pr ( f 2)=10 coeff log 10 ( f 2 /f 1), where
f1 is the first frequency;
f2 is one of the plurality of second frequencies;
coeff is an environment dependent parameter obtained through measurements;
Pr(f1) is the ambient interference value at the first frequency received from one of the access points; and
Pr(f2) is a calculated interference value at one of the plurality of second frequencies f2.
16. The method of claim 11 , comprising
receiving an average interference value from each of the access points;
receiving a first aggregate spectral efficiency value associated with a first frequency from each of the access points; and
calculating a plurality of second aggregate spectral efficiency values associated with a plurality of second frequencies for each of the access points, wherein
the aggregate demand is based on the first aggregate spectral efficiency value and the second aggregate spectral efficiency values.
17. The method of claim 16 , wherein
the first frequency is the lowest frequency in a band of the set of frequency bands; and
the first aggregate spectral efficiency value is based on,
A
S
E
(
f
1
)
=
a
+
b
N
∑
k
=
1
N
SINR
k
(
f
1
)
,
where
ASE(f1) is the aggregate spectral efficiency value associated with the first frequency;
a and b are constants;
N is a number of users;
k is the user for which the ASE is being calculated; and
SINR is a Signal to Interference-plus-Noise Ratio.
18. The method of claim 16 , wherein
the second aggregate spectral efficiency values are calculated for each access point such that:
ASE ( f 1)− ASE ( f 2)=10 coeff log 10 ( f 2 /f 1), where
f1 is the first frequency;
f2 is one of the second frequencies;
coeff is an environment dependent parameter obtained through measurements;
ASE(f1) is the first aggregate spectral efficiency value received from one of the access points; and
ASE(f2) is the calculated second aggregate spectral efficiency value at the second frequency value f2 for the access point.
19. The method of claim 11 , comprising
determining if the access points include two or more radio transmitters each capable of transmitting signals over a plurality of frequencies,
identifying groups of access points neighboring each of the access points, and allocating the set of frequency bands based on prioritizing the groups of access points, the interference map and the aggregate demand if the access points do not include two or more radio transmitters, and
allocating sub-bands of at least one of the frequency bands based on a utilization of the sub-bands, the interference map and the aggregate demand if the access points include two or more radio transmitters.
20. The method of claim 19 , comprising
calculating utilization of the sub-bands based on a utility calculation for each of the access points and configured to calculate a maximum utilization improvement based on a utilization of each of the set of frequency bands, and
allocating the sub-bands based on the utilization improvement.