Method and system for enhancing capacity of radios sharing spectrum
Methods and apparatuses for determining an assignment of frequency channels to radios of a spectrum access system are provided and which result in at least one of: (a) an enhanced transmit power-bandwidth product or an enhanced probable transmit power-bandwidth product for all radios, (b) diminished interference between radios of different nodes, and (c) diminishing changes to frequency channels either requested by or previously assigned to radios.
1. A method of determining frequency channel assignments to radios, comprising:
creating a new network graph or modifying a previously existing network graph;
using the new or the modified network graph, determining an interference network graph, for radios authorized to transmit in shared spectrum, using a transmit power spectral density level and a frequency channel specifically requested by each radio, where the interference network graph comprises at least two nodes and at least one interference edge connecting two nodes, where each node comprises one or more radios operated by a same operator, and where each radio is a base station configured to communicate with user equipment;
determining a chromatic number, z, of the interference network graph;
determining, using the chromatic number, combinations or permutations of frequency channel mappings for a number of frequencies, n, that can be assigned to at least one radio in each node of the interference network graph;
for each frequency channel mapping of the determined combinations or permutations of the frequency channel mappings that can be assigned to the radios of different nodes, determining a maximum transmit power spectral density level that is allowable for all radios of each node so that an aggregate interference level at at least one protection point will not exceed an aggregate interference threshold level;
using a cost function, determining an assignment of frequency channels to radios of each node that results in at least one of: (a) an enhanced transmit power-bandwidth product or an enhanced probable transmit power-bandwidth product for all radios, (b) diminished interference between radios of the different nodes, and (c) diminishing changes to frequency channels either requested by or previously assigned to radios; and
assigning the determined assignment of frequency channels and corresponding resulting enhanced transmit power-bandwidth product levels or probable enhanced transmit power-bandwidth product levels to corresponding radios, where the radios are configured to operate on their assigned frequencies and to transmit at their assigned enhanced transmit power-bandwidth product levels or probable enhanced transmit power-bandwidth product levels.
2. The method of claim 1 , wherein the cost function is dependent upon at least one of: a transmit power-bandwidth product term of each radio, a level of interference between radios, and changes to frequency channels either requested by or previously assigned to radios.
3. The method of claim 1 , wherein the cost function, C(m), is:
C
(
m
)
=
Σ
k
=
1
N
{
w
1
*
T
k
(
m
)
-
w
2
*
I
k
(
m
)
}
N
*
max
B
W
z
*
Σ
k
=
1
N
P
C
A
T
k
-
w
3
*
Σ
k
=
1
N
M
k
(
m
)
N
,
where T K is a throughput function of a k th radio for a m th frequency channel mapping;
I K is an average interference to the k th radio from other radios for the m th frequency channel mapping;
maxBW is a maximum bandwidth for a radio;
PCAT K is a maximum power of the k th radio;
N is a number of radio s in the interference network graph;
T
k
(
m
)
=
P
k
(
m
)
*
B
W
k
(
m
)
,
where P k is Tx power spectral density and BW k is a bandwidth for the k th radio for the m th frequency channel mapping;
I
k
(
m
)
=
Σ
l
≠
k
N
I
l
(
m
)
;
where I k is an aggregate interference level from other radios at a k th radio in overlapping bandwidth, and
where I l (m) is an interference at the k th radio from a l th radio in the overlapping bandwidth;
M k (m) is a mis-match factor; and
w 1 , w 2 and w 3 are weighting factors; and
wherein determining an assignment of frequency channels to the radios of each node comprises determining a maximum value of the cost function.
4. The method of claim 3 , wherein M k =0 if a k th radio of a corresponding node is assigned its requested frequency channel and M k =1 if the k th radio of the corresponding node is not assigned its requested frequency channel.
5. The method of claim 1 , wherein a value for the cost function is determined subject to at least one constraint by at least one of:
(a) assigning contiguous frequency channels to operators using a same radio access technology (RAT), transmission synchronization of network radios, and timing of uplink and downlink radios signals in time division duplexing radio networks;
(b) assigning frequency channels to other operators that are not adjacent to the frequency channels assigned to coordinated operators; and
(c) maintaining an absolute value of a difference between (i) a transmit power spectral density level of an individual radio and (ii) an average transmit power spectral density level of a set of radios utilizing a same frequency channel as the individual radio less than a delta power threshold level.
6. The method of claim 1 , further comprising receiving a requested frequency channel for a radio from an element management system of a radio access network which comprises the radio.
7. The method of claim 1 , wherein determining permutations of frequency channel mappings when utilizing opportunistic spectrum sharing comprises:
determining a number of combinations of
(
n
z
)
of the chromatic number z, where
(
n
z
)
=
n
!
z
!
(
n
-
z
)
!
when utilizing non-opportunistic spectrum sharing, where n is a number of frequency channels, and where the n is greater than z.
8. The method of claim 1 , wherein determining the interference network graph comprises determining an interference edge by if a sum of a first edge parameter and a second edge parameter divided by two exceeds an interference edge threshold level, where the first edge parameter is a ratio of an average power spectral density level of radios of a first node in an overlap region, formed by overlapping cell coverage areas, to an average power spectral density level of radios of a second node in the overlap region, and where the second edge parameter is an inverse of the first edge parameter.
9. A program product comprising a non-transitory processor readable medium on which program instructions are embodied, wherein the program instructions are configured, when executed by at least one programmable processor, to cause the at least one programmable processor to:
create a new network graph or modifying a previously existing network graph;
use the new or the modified network graph, determining an interference network graph, for radios authorized to transmit in shared spectrum, using a transmit power spectral density level and a frequency channel specifically requested by each radio, where the interference network graph comprises at least two nodes and at least one interference edge connecting two nodes, where each node comprises one or more radios operated by a same operator, and where each radio is a base station configured to communicate with user equipment;
determine a chromatic number, z, of the interference network graph;
determine, using the chromatic number, combinations or permutations of frequency channel mappings for a number of frequencies, n, that can be assigned to at least one radio in each node of the interference network graph;
for each frequency channel mapping of the determined combinations or permutations of the frequency channel mappings that can be assigned to the radios of different nodes, determine a maximum transmit power spectral density level that is allowable for all radios of each node so that an aggregate interference level at at least one protection point will not exceed an aggregate interference threshold level;
using a cost function, determine an assignment of frequency channels to radios of each node that results in at least one of: (a) an enhanced transmit power-bandwidth product or an enhanced probable transmit power-bandwidth product for all radios, (b) diminished interference between radios of the different nodes, and (c) diminishing changes to frequency channels either requested by or previously assigned to radios; and
assign the determined assignment of frequency channels and corresponding resulting enhanced transmit power-bandwidth product levels or probable enhanced transmit power-bandwidth product levels to corresponding radios, where the radios are configured to operate on their assigned frequencies and to transmit at their assigned enhanced transmit power-bandwidth product levels or probable enhanced transmit power-bandwidth product levels.
10. The program product of claim 9 , wherein the cost function is dependent upon at least one of: a transmit power-bandwidth product term of each radio, a level of interference between radios, and changes to frequency channels either requested by or previously assigned to radios.
11. The program product of claim 9 , wherein the cost function, C(m), is:
C
(
m
)
=
Σ
k
=
1
N
{
w
1
*
T
k
(
m
)
-
w
2
*
I
k
(
m
)
}
N
*
max
B
W
z
*
Σ
k
=
1
N
P
C
A
T
k
-
w
3
*
Σ
k
=
1
N
M
k
(
m
)
N
,
where T K is a throughput function of a k th radio for a m th frequency channel mapping;
I K is an average interference to the k th radio from other radios for the m th frequency channel mapping;
maxBW is a maximum bandwidth for a radio;
PCAT k is a maximum power of the k th radio;
N is a number of radio s in the interference network graph;
T
k
(
m
)
=
P
k
(
m
)
*
B
W
k
(
m
)
,
where is P k Tx power spectral density and BW k is a bandwidth for the k th radio for the m th frequency channel mapping;
I
k
(
m
)
=
Σ
l
≠
k
N
I
l
(
m
)
;
where I k is an aggregate interference level from other radios at a k th radio in overlapping bandwidth, and
where I l (m) is an interference at the k th radio from a l th radio in the overlapping bandwidth;
M k (m) is a mis-match factor; and
w 1 , w 2 and w 3 are weighting factors; and
wherein determine an assignment of frequency channels to the radios of each node comprises determine a maximum value of the cost function.
12. The program product of claim 11 , wherein M k =0 if a k th radio of a corresponding node is assigned its requested frequency channel and M k =1 if the k th radio of the corresponding node is not assigned its requested frequency channel.
13. The program product of claim 9 , wherein a value for the cost function is determined subject to at least one constraint by at least one of:
(a) assigning contiguous frequency channels to operators using a same radio access technology (RAT), transmission synchronization of network radios, and timing of uplink and downlink radios signals in time division duplexing radio networks;
(b) assigning frequency channels to other operators that are not adjacent to the frequency channels assigned to coordinated operators; and
(c) maintaining an absolute value of a difference between (i) a transmit power spectral density level of an individual radio and (ii) an average transmit power spectral density level of a set of radios utilizing a same frequency channel as the individual radio less than a delta power threshold level.
14. The program product of claim 9 , wherein determine permutations of frequency channel mappings when utilizing opportunistic spectrum sharing comprises:
determine a number of combinations of
(
n
z
)
of the chromatic number z, where
(
n
z
)
=
n
!
z
!
(
n
-
z
)
!
when utilizing non-opportunistic spectrum sharing, where n is a number of frequency channels, and where the n is greater than z.
15. The program product of claim 9 , wherein determine the interference network graph comprises determine an interference edge by if a sum of a first edge parameter and a second edge parameter divided by two exceeds an interference edge threshold level, where the first edge parameter is a ratio of an average power spectral density level of radios of a first node in an overlap region, formed by overlapping cell coverage areas, to an average power spectral density level of radios of a second node in the overlap region, and where the second edge parameter is an inverse of the first edge parameter.
16. A system, comprising:
a processing circuitry configured to be coupled to at least one radio and configured to:
create a new network graph or modifying a previously existing network graph;
use the new or the modified network graph, determining an interference network graph, for radios authorized to transmit in shared spectrum, using a transmit power spectral density level and a frequency channel specifically requested by each radio, where the interference network graph comprises at least two nodes and at least one interference edge connecting two nodes, where each node comprises one or more radios operated by a same operator, and where each radio is a base station configured to communicate with user equipment;
determine a chromatic number, z, of the interference network graph;
determine, using the chromatic number, combinations or permutations of frequency channel mappings for a number of frequencies, n, that can be assigned to at least one radio in each node of the interference network graph;
for each frequency channel mapping of the determined combinations or permutations of the frequency channel mappings that can be assigned to the radios of different nodes, determine a maximum transmit power spectral density level that is allowable for all radios of each node so that an aggregate interference level at at least one protection point will not exceed an aggregate interference threshold level;
using a cost function, determine an assignment of frequency channels to radios of each node that results in at least one of: (a) an enhanced transmit power-bandwidth product or an enhanced probable transmit power-bandwidth product for all radios, (b) diminished interference between radios of the different nodes, and (c) diminishing changes to frequency channels either requested by or previously assigned to radios; and
assign the determined assignment of frequency channels and corresponding resulting enhanced transmit power-bandwidth product levels or probable enhanced transmit power-bandwidth product levels to corresponding radios, where the radios are configured to operate on their assigned frequencies and to transmit at their assigned enhanced transmit power-bandwidth product levels or probable enhanced transmit power-bandwidth product levels.
17. The system of claim 16 , wherein the cost function is dependent upon at least one of: a transmit power-bandwidth product term of each radio, a level of interference between radios, and changes to frequency channels either requested by or previously assigned to radios.
18. The system of claim 16 , wherein the cost function, C(m), is:
C
(
m
)
=
Σ
k
=
1
N
{
w
1
*
T
k
(
m
)
-
w
2
*
I
k
(
m
)
}
N
*
max
B
W
z
*
Σ
k
=
1
N
P
C
A
T
k
-
w
3
*
Σ
k
=
1
N
M
k
(
m
)
N
,
where T K is a throughput function of a k th radio for a m th frequency channel mapping;
I K is an average interference to the k th radio from other radios for the m th frequency channel mapping;
maxBW is a maximum bandwidth for a radio;
PCAT k is a maximum power of the k th radio;
N is a number of radio s in the interference network graph;
T
k
(
m
)
=
P
k
(
m
)
*
B
W
k
(
m
)
,
where is P k Tx power spectral density and BW k is a bandwidth for the k th radio for the m th frequency channel mapping;
I
k
(
m
)
=
Σ
l
≠
k
N
I
l
(
m
)
;
where I k is an aggregate interference level from other radios at a k th radio in overlapping bandwidth, and
where I l (m) is an interference at the k th radio from a l th radio in the overlapping bandwidth;
M k (m) is a mis-match factor; and
w 1 , w 2 and w 3 are weighting factors; and
wherein determine an assignment of frequency channels to the radios of each node comprises determine a maximum value of the cost function.
19. The system of claim 18 , wherein M k =0 if a k th radio of a corresponding node is assigned its requested frequency channel and M k =1 if the k th radio of the corresponding node is not assigned its requested frequency channel.
20. The system of claim 16 , wherein a value for a cost function is determined subject at least one constraint by at least one of:
(a) assigning contiguous frequency channels to operators using a same radio access technology (RAT), transmission synchronization of network radios, and timing of uplink and downlink radios signals in time division duplexing radio networks;
(b) assigning frequency channels to other operators that are not adjacent to the frequency channels assigned to coordinated operators; and
(c) maintaining an absolute value of a difference between (i) a transmit power spectral density level of an individual radio and (ii) an average transmit power spectral density level of a set of radios utilizing a same frequency channel as the individual radio less than a delta power threshold level.
21. The system of claim 16 , wherein determine permutations of frequency channel mappings when utilizing opportunistic spectrum sharing comprises:
determine a number of combinations of
(
n
z
)
or the chromatic number z, where
(
n
z
)
=
n
!
z
!
(
n
-
z
)
!
when utilizing non-opportunistic spectrum sharing, where n is a number of frequency channels, and where the n is greater than z.
22. The system of claim 16 , wherein determine the interference network graph comprises determine an interference edge by if a sum of a first edge parameter and a second edge parameter divided by two exceeds an interference edge threshold level, where the first edge parameter is a ratio of an average power spectral density level of radios of a first node in an overlap region, formed by overlapping cell coverage areas, to an average power spectral density level of radios of a second node in the overlap region, and where the second edge parameter is an inverse of the first edge parameter.
23. The system of claim 16 , wherein at least one of an environmental sensing capability system is coupled to the processing circuitry.
24. The system of claim 16 , wherein at least one of at least one external database, and at least one other spectrum access system are coupled to the processing circuitry.
25. The system of claim 16 , wherein the at least one radio comprises a radio element management system.