Power-limit reporting in a communication system using carrier aggregation
Methods inform an eNodeB on the transmit power status of a user equipment in a mobile communication system using component carrier (CC) aggregation. Also described is an implementation of these methods by hardware and in software. The invention proposes procedures that allow the eNodeB to recognize the power usage status of a UE in a communication system using carrier aggregation. The UE indicates to the eNodeB when the UE is close to using its total maximum UE transmit power or when it has exceeded the same. This is achieved by the UE including indicator(s) and/or new MAC CEs to one or more protocol data units transmitted on respective component carriers within a single sub-frame that is providing the eNodeB with power status information. The MAC CEs may report a per-UE power headroom. Alternatively, the MAC CEs may report per-CC power headrooms and/or power reductions applied to the respective uplink CCs.
1. A communication apparatus comprising:
circuitry which, in operation, generates a power status report of the communication apparatus in a communication system using component carrier aggregation, in which two or more component carriers (CCs) are aggregated, wherein the power status report includes: (i) a CC specific maximum transmission power, P CMAX,c , for each configured and activated uplink CC, wherein PCMAX,c shall be set within following bounds:
P CMAX_L,c <=P CMAX,c <=P CMAX_H,c
where PCMAX_L,c is a lower bound and PCMAX_H,c is a higher bound of a CC specific maximum transmission power, and (ii) a power headroom report indicative of a difference between the CC specific maximum transmission power, P CMAX,c , and an estimated communication apparatus transmit power, per each configured and activated uplink CC,
wherein the CC specific maximum transmission power, P CMAX,c , for each configured and activated CC is included in the power status report when a resource is allocated to the configured and activated uplink CC for the communication apparatus; and
a transmitter configured to transmit the power status report to the base station.
2. The communication apparatus according to claim 1 , wherein the power status report is triggered at activation of a configured uplink CC.
3. The communication apparatus according to claim 1 , wherein the power status report is for Uplink Shared Channel (UL-SCH) transmission per configured and activated uplink CC.
4. The communication apparatus according to claim 1 , wherein the power status report for a sub-frame takes into account a transmission power of a Physical Uplink Control Channel (PUCCH) used by the UE in the same sub-frame.
5. The communication apparatus according to claim 1 , wherein in case no resource allocation is available in a sub-frame, the power status report takes into account a predefined uplink grant or a predefined Physical Uplink Shared Channel (PUSCH) power.
6. The communication apparatus according to claim 1 , wherein the power headroom reports on multiple configured and activated uplink CCs are included in a single Media Access Control (MAC) control element, wherein the MAC control element includes a bitmap and a bit set at a certain position of the bitmap indicates the presence of a power headroom report field for a corresponding CC.
7. The communication apparatus according to claim 1 , wherein the power status report includes indicators that indicate, for each (ii) power headroom report, the presence of the associated (i) CC specific maximum transmission power, PCMAX,c, respectively.
8. The communication apparatus according to claim 1 , wherein the CC specific maximum transmission power, P CMAX,c , is a nominal communication apparatus maximum transmit power.
9. A method implemented in a communication apparatus, the method comprising:
generating, by the communication apparatus in a communication system using component carrier aggregation, in which two or more component carriers (CCs) are aggregated, a power status report that includes: (i) a CC specific maximum transmission power, P CMAX,c , for each configured and activated uplink CC, wherein P CMAX,c shall be set within following bounds:
P CMAX_L,c <=P CMAX,c <=P CMAX_H,c
where P CMAX_L,c is a lower bound and P CMAX_H,c is a higher bound of a CC specific maximum transmission power, and (ii) a power headroom report indicative of a difference between the CC specific maximum transmission power, P CMAX,c , and an estimated UE transmit power, per each configured and activated uplink CC,
wherein the CC specific maximum transmission power, P CMAX,c , for each configured and activated CC is included in the power status report when a resource is allocated to the configured and activated uplink CC for the communication apparatus; and
transmitting, by the communication apparatus, the power status report to a base station.
10. The method according to claim 9 , wherein the power status report is triggered at activation of a configured uplink CC.