Power headroom report method and apparatus for mobile communication system supporting carrier aggregation

Abstract

A method and user equipment (UE) for obtaining power headroom information in a communication system are provided. The method includes acquiring information for a path loss reference, wherein the information for the path loss reference indicates whether the UE applies as the path loss reference either a downlink of a primary cell or a downlink of a secondary cell (SCell), triggering a power headroom report (PHR) if a prohibitPHR-Timer expires and a path loss is changed more than a threshold for at least one activated cell which is used as the path loss reference, and obtaining power headroom information for each activated cell, if extended PHR is used and an uplink resource is allocated for new transmission.

What is claimed is: 
     
       1. A method for obtaining, by a user equipment (UE), power headroom information in a communication system, the method comprising:
 acquiringreceiving, from a base station, a secondary cell configuration message including first information foron a path loss change and second information on a path loss reference, wherein the first information for the path loss reference indicates whether the UE applies as the path loss reference either a downlink of a primary cell or a downlink of a secondary cell (SCell)on the path loss change indicates a threshold for triggering a power headroom report (PHR) and the second information on the path loss reference indicates one reference cell among a primary cell and the secondary cell; 
 triggering a power headroom report (PHR) if the PHR for activated cells in a case that both a prohibitPHR-Timer expires and a path loss is changed more than a the threshold for at least one activated cell which is used as the path loss reference cell among the activated cells; and 
 obtainingcalculating power headroom information for each activated cell with a configured uplink, if extended PHR is used andin a case that an uplink resource is allocated for new transmission; and 
 transmitting the power headroom information for each activated cell with the configured uplink and an indicator for each activated cell with the configured uplink, 
 wherein the indicator indicates whether the power headroom information is based on a real physical uplink channel transmission or a physical uplink channel reference format, 
 wherein, in a case that the power headroom information is based on a real transmission of a physical uplink channel, the power headroom information is calculated based on a parameter related to a number of resource blocks and a parameter derived from modulation and coding scheme (MCS), and 
 wherein, in a case that the power headroom information is based on the physical uplink channel reference format, the power headroom information is calculated based on a maximum uplink transmission power, which is equal to one of a maximum allowed UE output power (P EMAX ) or a nominal UE power (P powerclass ), with the parameter related to the number of resource blocks being set to 0 and the parameter derived from the MCS being set to 0. 
 
     
     
       2. The method of  claim 1 , wherein the downlink of the secondary cell corresponding to an uplink is indicated by adding the SCell. 
     
     
       3. The method of  claim 1 , wherein the power headroom information for each activated cell is multiplexed with a higher layer data. 
     
     
       4. The method of  claim 1 , further comprising:
 generating a media access control (MAC) protocol data unit (PDU) including wherein the power headroom information for each activated cell and an indicator for maximum transmit power information with the configured uplink is multiplexed with higher layer data. 
 
     
     
       5. The method of claim  4   1 , wherein if in a case that the indicator is 0 the indicator indicates the first type maximum transmit power information real physical uplink channel transmission, and
 wherein if in a case that the indicator is 1 the indicator indicates the second type maximum transmit power information physical uplink channel reference format. 
 
     
     
       6. A user equipment (UE) for obtaining power headroom information in a communication system, the UE comprising:
 a transceiver configured to transmit and receive a signal; and 
 a controller configured to:
 acquirereceive, from a base station, a secondary cell configuration message including first information foron a path loss change and second information on a path loss reference, wherein the first information for the path loss reference indicates whether the UE applies as the path loss reference either a downlink of a primary cell or a downlink of a secondary cell (SCell)on the path loss change indicates a threshold for triggering a power headroom report (PHR) and the second information on the path loss reference indicates one reference cell among a primary cell and the secondary cell, 
 trigger a power headroom report (PHR) if the PHR for activated cells in a case that both a prohibitPHR-Timer expires and a path loss is changed more than a the threshold for at least one activated cell which is used as the path loss reference cell among the activated cells, and 
 obtaincalculate power headroom information for each activated cell with a configured uplink, if extended PHR is usedin a case that an uplink resource is allocated for new transmission, and an uplink resource is allocated for new transmission 
 transmit the power headroom information for each activated cell with the configured uplink and an indicator for each activated cell with the configured uplink, 
 
 wherein the indicator indicates whether the power headroom information is based on a real physical uplink channel transmission or a physical uplink channel reference format, and 
 wherein, in a case that the power headroom information is based on a real transmission of a physical uplink channel, the controller is further configured to calculate the power headroom information based on a parameter related to a number of resource blocks and a parameter derived from modulation and coding scheme (MCS), and 
 wherein, in a case that the power headroom information is based on the physical uplink channel reference format, the controller is further configured to calculate the power headroom information based on a maximum uplink transmission power, which is equal to one of a maximum allowed UE output power (P EMAX ) or a nominal UE power (P powerclass ), with the parameter related to a number of resource blocks being set to 0 and a parameter derived from the MCS being set to 0. 
 
     
     
       7. The UE of  claim 6 , wherein the downlink of the secondary cell corresponding to an uplink is indicated by adding the SCell. 
     
     
       8. The UE of  claim 6 , wherein the power headroom information for each activated cell is multiplexed with a higher layer data. 
     
     
       9. The UE of  claim 6 , wherein the controller is further configured to generate a media access control (MAC) protocol data unit (PDU) including the power headroom information for each activated cell and an indicator for maximum transmit power information with the configured uplink is multiplexed with higher layer data. 
     
     
       10. The UE of claim  9   6 , wherein if the indicator is 0 the indicator indicates the first type maximum transmit power information real physical uplink channel transmission, and
 wherein if the indicator is 1 the indicator indicates the second type maximum transmit power information physical uplink channel reference format. 
 
     
     
       11. A method for receiving power headroom information by a base station in a communication system, the method comprising:
 transmitting, to a user equipment (UE), a secondary cell configuration message including first information for a path loss reference to a user equipment (UE), wherein the information for the path loss reference indicates whether the UE applies as the path loss reference either a downlink of a primary cell or a downlink of a secondary cell (SCell) on a path loss change and second information on a path loss reference, wherein the first information on the path loss change indicates a threshold for triggering a power headroom report (PHR) and the second information on the path loss reference indicates one reference cell among a primary cell and the secondary cell; and 
 receiving a the power headroom information for each activated cell from the terminal with a configured uplink and an indicator for each activated cell with the configured uplink in a case that an uplink resource is allocated for new transmission, 
 wherein a power headroom report (PHR) the PHR for the power headroom information is triggered if in a case that both a prohibitPHR-Timer expires and a path loss is changed more than a the threshold for at least one activated cell which is used as the path loss reference cell among activated cells, 
 wherein the indicator indicates whether power headroom information is based on a real physical uplink channel transmission or a physical uplink channel reference format, and 
 wherein, in a case that the power headroom information is based on a real transmission of a physical uplink channel, the power headroom information is calculated based on a parameter related to a number of resource blocks and a parameter derived from modulation and coding scheme (MCS), and 
 wherein, in a case that the power headroom information is based on the physical uplink channel reference format, the power headroom information is calculated based on a maximum uplink transmission power, which is equal to one of a maximum allowed UE output power (P EMAX ) or a nominal UE power (P powerclass ), with the parameter related to the number of resource blocks being set to 0 and the parameter derived from the MCS being set to 0. 
 
     
     
       12. The method of  claim 11 , wherein the downlink of the secondary cell corresponding to an uplink is indicated by adding the SCell. 
     
     
       13. The method of  claim 11 , wherein the power headroom information for each activated cell is multiplexed with a higher layer data. 
     
     
       14. The method of  claim 11 , further comprising:
 receiving a media access control (MAC) protocol data unit (PDU) including wherein the power headroom information for each activated cell and an indicator for maximum transmit power information with the configured uplink is multiplexed with higher layer data. 
 
     
     
       15. The method of claim  14   11 , wherein if in a case that the the indicator is 0 the indicator indicates the first type maximum transmit power information real physical uplink channel transmission, and
 wherein if in a case that the indicator is 1 the indicator indicates the second type maximum transmit power information physical uplink channel reference format. 
 
     
     
       16. A base station for receiving power headroom information in a communication system, the base station comprising:
 a transceiver configured to transmit and receive a signal; and 
 a controller configured to:
 transmit, to a user equipment (UE), a secondary cell configuration message including first information for a path loss reference to a user equipment (UE), wherein the information for the path loss reference indicates whether the UE applies as the path loss reference either a downlink of a primary cell or a downlink of a secondary cell (SCell) on a path loss change and second information on a path loss reference, wherein the first information on the path loss change indicates a threshold for triggering a power headroom report (PHR) and the second information on the path loss reference indicates one reference cell among a primary cell and the secondary cell, and 
 receive a the power headroom information for each activated cell from the terminal with a configured uplink and an indicator for each activated cell with the configured uplink in a case that an uplink resource is allocated for new transmission, 
 
 wherein a power headroom report (PHR) the PHR for the power headroom information is triggered if in a case that both a prohibitPHR-Timer expires and a path loss is changed more than a the threshold for at least one activated cell which is used as the path loss reference cell among activated cells, 
 wherein the indicator indicates whether power headroom information is based on a real physical uplink channel transmission or a physical uplink channel reference format, 
 wherein, in a case that the power headroom information is based on a real transmission of a physical uplink channel, the controller is further configured to calculate the power headroom information based on a parameter related to a number of resource blocks and a parameter derived from modulation and coding scheme (MCS), and 
 wherein, in a case that the power headroom information is based on the physical uplink channel reference format, the controller is further configured to calculate the power headroom information based on a maximum uplink transmission power, which is equal to one of a maximum allowed UE output power (P EMAX ) or a nominal UE power (P powerclass ), with the parameter related to a number of resource blocks being set to 0 and a parameter derived from the MCS being set to 0. 
 
     
     
       17. The base station of  claim 16 , wherein the downlink of the secondary cell corresponding to an uplink is indicated by adding the SCell. 
     
     
       18. The base station of  claim 16 , wherein the power headroom information for each activated cell is multiplexed with a higher layer data. 
     
     
       19. The base station of  claim 16 , wherein the controller is further configured to receive a media access control (MAC) protocol data unit (PDU) including the power headroom information for each activated cell and an indicator for maximum transmit power information with the configured uplink is multiplexed with higher layer data. 
     
     
       20. The base station of claim  19   16 , wherein if the indicator is 0 the indicator indicates the first type maximum transmit power information real physical uplink channel transmission, and
 wherein if the indicator is 1 the indicator indicates the second type maximum transmit power information physical uplink channel reference format.