Uplink power headroom reporting for carrier aggregation
A method for reporting power headroom is disclosed. Power headroom may be reported across all carriers (wideband), for a specific carrier, or for a carrier group. The formula used to calculate the power headroom depends on whether the carrier (or a carrier in the carrier group) has a valid uplink grant. If the carrier or carrier group does not have a valid uplink grant, the power headroom may be calculated based on a reference grant. The power headroom is calculated by a wireless transmit/receive unit and is reported to an eNodeB.
1. A method for reporting a carrier-specific power headroom for aggregated carriers, the method comprising:
determining a first carrier from a plurality of aggregated carriers that has a physical uplink shared channel (PUSCH) transmission in a subframe i;
determining a second carrier from the plurality of aggregated carriers that does not have a PUSCH transmission in a subframe i;
calculating a first power headroom according to the formula:
PH ( k 1 ,i )= P CMAX carrier ( k 1 )− P PUSCH — UG ( k 1 ,i )
where k 1 is the first carrier, and P PUSCH — UG (k 1 ,i) is a transmit power for the first carrier in subframe i prior to imposing maximum power limitations; and
calculating a second power headroom for the second carrier according to the formula:
PH ( k 2 ,i )= P CMAX — carrier ( k 2 )− P PUSCH — REF ( k 2 ,i )
where k 2 is the second carrier, and P PUSCH — REF (k 2 ,i) is a transmit power determined according to a reference grant allocation.
2. The method according to claim 1 , wherein:
P
CMAX_carrier
(
k
)
10
log
10
(
(
BW
k
∑
k
=
1
,
K
,
K
BW
k
)
×
10
P
CMAX
10
)
where BW k is the bandwidth for carrier k, K is a maximum number of carriers, P CMAX is a total maximum transmit power, and the formula is used for all sub-bands or carriers across all power amplifiers at a wireless transmit/receive unit.
3. The method according to claim 2 , wherein the sum of P CMAX — carrier (k) for all carriers k is limited by P CMAX such that
∑
k
=
1
,
K
,
K
P
CMAX_carrier
(
k
)
≤
P
CMAX
.
4. The method according to claim 1 , wherein:
P
CMAX_carrier
(
k
)
=
10
log
10
(
(
BW
k
∑
k
∈
Ω
BW
k
)
×
10
P
CMAX
10
)
where BW k is the bandwidth for carrier k, Ω is a set of active carriers, P CMAX is a total maximum transmit power, and the formula is used for a subset of carriers that have an active grant in subframe i for all sub-bands or carriers across all power amplifiers at a wireless transmit/receive unit.
5. The method according to claim 4 , wherein the sum of P CMAX — carrier (k) for all carriers k in Ω is limited by P CMAX such that
∑
k
∈
Ω
P
CMAX_carrier
(
k
)
≤
P
CMAX
.
6. The method according to claim 1 , wherein:
P
CMAX_carrier
(
k
)
=
10
log
10
(
(
BW
k
∑
k
∈
Ω
BW
k
)
×
10
P
CMAX
(
m
)
10
)
where BW k is the bandwidth for carrier k, Ω m is a set of carriers of carrier group m, and P CMAX (m) is a maximum transmit power for carrier group m.
7. The method according to claim 6 , wherein the sum of P CMAX — carrier (k) for all carriers k in Ω m is limited by P CMAx (m) such that
∑
k
∈
Ω
m
P
CMAX_carrier
(
k
)
≤
P
CMAX
(
m
)
.
8. The method according to claim 1 , wherein:
P
CMAX_carrier
(
k
)
=
10
log
10
(
(
BW
k
∑
k
∈
Ω
m
⋂
carrierkhasgrant
BW
k
)
×
10
P
CMAX
(
m
)
10
)
where BW k is the bandwidth for carrier k, Ω m is a set of carriers of carrier group m, and P CMAX (m) is a maximum transmit power for carrier group m.
9. The method according to claim 8 , wherein the sum of P CMAX — carrier (k) for all carriers k in Ω m is limited by P CMAX (m) such that
∑
k
∈
Ω
m
⋂
carrierkhasgrant
P
CMAX_carrier
(
k
)
≤
P
CMAX
(
m
)
.
10. The method of claim 1 , further comprising reporting the first power headroom and the second power headroom.
11. The method of claim 1 , wherein P PUSCH —UG (k,i) is defined for k carrier according to the formula:
10 log 10 (M PUSCH (i)+α(j)×PL+Δ TF (i)+f(i)
12. The method of claim 11 , wherein P CMAX — carrier (k) is a maximum WTRU transmit power of the k carrier.
13. The method of claim 1 , wherein the sum of P CMAX — carrier (k 2 ) and P CMAX — carrier (k 1 ) is less than or equal to a P CMAX for the plurality of aggregated carriers.
14. The method of claim 1 , further comprising determining a third carrier that does not have a PUSCH transmission in a subframe i.
15. The method of claim 14 , further comprising calculating a third power headroom for the third carrier according to the formula:
PH ( k 3 , i )= P CMAX — carrier ( k 3 , i )
where k 3 is the third carrier, and P PUSCH — REF (k 3 , i ) is a transmit power determined according to a reference grant allocation.
16. The method of claim 15 , further comprising reporting the first power headroom, the second power headroom, and the third power headroom.
17. A method for reporting a carrier-specific power headroom, comprising:
calculating a maximum power per carrier, P CMAX — carrier ;
on a condition that the carrier does not have a valid uplink grant, calculating a power headroom using a reference grant according to the formula:
PH ( k,i )= P CMAX — carrier ( k )− P PUSCH — REF ( k,i )
where k is a carrier number, i is a subframe for which the power headroom is to be reported, and P PUSCH — REF (k,i) is defined as
P PUSCH — REF ( k,i )= f 1 — REF ( P PUSCH — REF ( n,i ))+α×( PL ( k )− f 2 — REF ( PL ( n )))
where f 1 — REF (*) is a function of a reference carrier-specific wireless transmit/receive unit transmit power, n≠k and carrier n belongs to the set of carriers with a valid uplink grant, α is a cell-specific parameter, PL(k) is a pathloss estimate on carrier k, and f 2 — REF (*) is a function of a reference carrier-specific pathloss; and
reporting the calculated power headroom.
18. The method according to claim 17 , wherein calculating the maximum power per carrier is based on the formula:
P
CMAX_carrier
(
k
)
=
10
log
10
(
(
BW
k
∑
k
=
1
,
K
,
K
BW
k
)
×
10
P
CMAX
10
)
where BW k is the bandwidth for carrier k, K is a maximum number of carriers, P CMAX is a total maximum transmit power, and the formula is used for all sub-bands or carriers across all power amplifiers at a wireless transmit/receive unit.
19. The method according to claim 18 , wherein the sum of P CMAX — carrier (k) for all carriers k is limited by P CMAX such that
∑
k
=
1
,
K
,
K
P
CMAX_carrier
(
k
)
≤
P
CMAX
.
20. The method according to claim 17 , wherein calculating the maximum power per carrier is based on the formula:
P
CMAX_carrier
(
k
)
=
10
log
10
(
(
BW
k
∑
k
∈
Ω
BW
k
)
×
10
P
CMAX
10
)
where BW k is the bandwidth for carrier k, Ω is a set of active carriers, P CMAX is a total maximum transmit power, and the formula is used for a subset of carriers that have an active grant in subframe i for all sub-bands or carriers across all power amplifiers at a wireless transmit/receive unit.
21. The method according to claim 20 , wherein the sum of P CMAX — carrier (k) for all carriers k in Ω is limited by P CMAX such that
∑
k
∈
Ω
P
CMAX_carrier
(
k
)
≤
P
CMAX
.
22. The method according to claim 17 , wherein calculating the maximum power per carrier is based on the formula:
P
CMAX_carrier
(
k
)
=
10
log
10
(
(
BW
k
∑
k
∈
Ω
m
BW
k
)
×
10
P
CMAX
(
m
)
10
)
where BW k is the bandwidth for carrier k, Ω m is a set of carriers of carrier group m, and P CMAX (m) is a maximum transmit power for carrier group m.
23. The method according to claim 22 , wherein the sum of P CMAX — carrier (k) for all carriers k in Ω m is limited by P CMAX (m) such that
∑
k
∈
Ω
m
P
CMAX_carrier
(
k
)
≤
P
CMAX
(
m
)
.
24. A method for reporting a carrier group-specific power headroom, comprising:
calculating a maximum power per carrier, P CMAX — carrier (k);
on a condition that at least one carrier in the carrier group has a valid uplink grant, calculating a group power headroom according to the formula:
PH
(
m
,
i
)
=
10
log
10
(
∑
k
∈
Ω
m
10
P
CMAX_carrier
(
k
)
10
)
-
10
log
10
(
∑
k
∈
Ω
m
10
P
PUSCH_UG
(
k
,
i
)
10
)
where m is a carrier group number, i is a subframe number in which at least one carrier in the carrier group has a valid uplink grant, Ω m is a set of carriers of carrier group m, and P PUSCH — UG (k,i) is a transmit power for carrier k in subframe i prior to imposing maximum power limitations; and
reporting the calculated power headroom.
25. The method according to claim 24 , wherein calculating the maximum power per carrier is based on the formula:
P
CMAX_carrier
(
k
)
=
10
log
10
(
(
BW
k
∑
k
=
1
,
K
,
K
BW
k
)
×
10
P
CMAX
10
)
where BW k is the bandwidth for carrier k, K is a maximum number of carriers, P CMAX is a total maximum transmit power, and the formula is used for all sub-bands or carriers across all power amplifiers at a wireless transmit/receive unit.
26. The method according to claim 25 , wherein the sum of P CMAX — carrier (k) for all carriers k in Ω is limited by P CMAX such that
∑
k
=
1
,
K
,
K
P
CMAX_carrier
(
k
)
≤
P
CMAX
.
27. The method according to claim 24 , wherein calculating the maximum power per carrier is based on the formula:
P
CMAX_carrier
(
k
)
=
10
log
10
(
(
BW
k
∑
k
∈
Ω
BW
k
)
×
10
P
CMAX
10
)
where BW k is the bandwidth for carrier k, Ω is a set of active carriers, P CMAX is a total maximum transmit power, and the formula is used for a subset of carriers across all power amplifiers at a wireless transmit/receive unit.
28. The method according to claim 27 , wherein the sum of P CMAX — carrier (k) for all carriers k in Ω is limited by P CMAX such that
∑
k
∈
Ω
P
CMAX_carrier
(
k
)
≤
P
CMAX
.
29. A method for reporting a carrier group-specific power headroom, comprising:
calculating a maximum power per carrier, P CMAX — carrier (k);
on a condition that no carrier in the carrier group has a valid uplink grant, calculating a group power headroom using a reference grant according to the formula:
PH
(
m
,
i
)
=
10
log
10
(
∑
k
∈
Ω
m
10
P
CMAX_carrier
(
k
)
10
)
-
10
log
10
(
∑
k
∈
Ω
m
10
P
PUSCH_REF
(
k
,
i
)
10
)
where m is a carrier group number, i is a subframe number for which the power
headroom is to be reported, Ω m , is a set of carriers of carrier group m, and P PUSCH — REF (k,i) is defined as
P PUSCH — REF ( k,i )= f 1 — REF ( P PUSCH — REF ( n,i )+α×( PL ( k )− f 2 — REF ( PL ( n )))
where f 1 — REF (*) is a function of a reference carrier-specific WTRU transmit power, n≠k and carrier n belongs to the set of carriers with a valid uplink grant, α is a cell-specific parameter, PL(k) is a pathloss estimate on carrier k, and f 2 — REF (*) is a function of a reference carrier-specific pathloss; and
reporting the calculated power headroom.
30. The method according to claim 29 , wherein calculating the maximum power per carrier is based on the formula:
P
CMAX_carrier
(
k
)
=
10
log
10
(
(
BW
k
∑
k
=
1
,
K
,
K
BW
k
)
×
10
P
CMAX
10
)
where BW k is the bandwidth for carrier k, K is a maximum number of carriers, P CMAX is a total maximum transmit power, and the formula is used for all sub-bands or carriers across all power amplifiers at a wireless transmit/receive unit.
31. The method according to claim 30 , wherein the sum of P CMAX — carrier (k) for all carriers k in Ω is limited by P CMAX such that
∑
k
=
1
,
K
,
K
P
CMAX_carrier
(
k
)
≤
P
CMAX
.
32. The method according to claim 29 , wherein calculating the maximum power per carrier is based on the formula:
P
CMAX_carrier
(
k
)
=
10
log
10
(
(
BW
k
∑
k
∈
Ω
BW
k
)
×
10
P
CMAX
10
)
33. The method according to claim 32 , wherein the sum of P CMAX — carrier (k) for all carriers k in Ω is limited by P CMAX such that
∑
Ω
P
CMAX_carrier
(
k
)
≤
P
CMAX
.
34. A method for reporting a carrier group-specific power headroom, comprising:
on a condition that at least one carrier in the carrier group has a valid uplink grant, calculating a group power headroom according to the formula:
PH
(
m
,
i
)
=
P
CMAX
(
m
)
-
10
log
10
(
∑
k
=
Ω
m
P
PUSCH_REF
(
k
,
i
)
10
)
where m is a carrier group number, i is a subframe number in which at least one carrier in the carrier group has a valid uplink grant, Ω m is a set of carriers of carrier group m, P CMAX (m) is a configured maximum allowed wireless transmit/receive unit (WTRU) transmit power for carrier group m, and P PUSCH — UG (k,i) is a transmit power for carrier k in subframe i prior to imposing maximum power limitations; and
reporting the calculated power headroom.
35. A method for reporting a earner group-specific power headroom, comprising:
on a condition that no carrier in the carrier group has a valid uplink grant, calculating a group power headroom using a reference grant according to the formula:
PH
(
m
,
i
)
=
P
CMAX
(
m
)
-
10
log
10
(
∑
k
=
Ω
m
P
PUSCH_REF
(
k
,
i
)
10
)
where m is a carrier group number, i is a subframe number for which the power headroom is to be reported, Ω m is a set of carriers of carrier group m, P CMAX (m) is a configured maximum allowed wireless transmit/receive unit (WTRU) transmit power for carrier group m, and P PUSCH — REF (k,i) is defined as
P PUSCH — REF ( k,i )= f 1 — REF ( P PUSCH — REF ( n,i ))+α×( PL ( k )− f 2 — REF ( PL ( n )))
where f 1 — REF (*) is a function of a reference carrier-specific WTRU transmit power, n≠k and carrier n belongs to the set of carriers with a valid uplink grant, α is a cell-specific parameter, PL(k) is a pathloss estimate on carrier k, and f 2 — REF (*) is a function of a reference carrier-specific pathloss; and
reporting the calculated power headroom.
36. A method for reporting carrier-specific power headroom for aggregated carriers, the method comprising:
determining a first maximum power for a first carrier;
determining a first transmit power that corresponds to the first carrier;
calculating a first power headroom for the first carrier;
determining a second maximum power for a second carrier from a plurality of aggregated carriers that does not have a physical uplink shared channel (PUSCH) transmission in a subframe i;
calculating a second power headroom for the second carrier using a reference grant; and
reporting the calculated first and second power headroom.
37. The method according to claim 36 , wherein the first carrier has a valid uplink grant, and the first transmit power comprises a transmit power for the first carrier prior to imposing maximum power limitations.
38. The method according to claim 36 wherein the second carrier does not have a valid uplink grant, and a second transmit power comprises a reference transmit power.
39. The method according to claim 38 , further comprising:
calculating the reference transmit power based on a pathloss estimate on the second carrier, a pathloss on at least one carrier that has a valid uplink grant, and a transmit power for the at least one carrier that has a valid uplink grant.
40. The method according to claim 38 , further comprising:
calculating the reference transmit power using a predetermined value reference.
41. The method according to claim 38 , further comprising:
calculating the reference transmit power using at least one parameter of at least one carrier that has a valid uplink grant.
42. The method according to claim 36 , wherein the first maximum power for the first carrier is pre-defined by higher layer configurations.
43. The method according to claim 36 , wherein calculating the first power headroom comprises determining a difference between the first maximum power and the first transmit power.
44. The method according to claim 36 , wherein calculating the second power headroom comprises determining a difference between a second maximum power and the second transmit power.