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:
 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.   
     
     
       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 the power headroom information for each activated cell and an indicator for maximum transmit power information.   
     
     
       5. The method of  claim 4 , wherein if the indicator is 0 the indicator indicates the first type maximum transmit power information, and
 wherein if the indicator is 1 the indicator indicates the second type maximum transmit power information.   
     
     
       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:
 acquire 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), 
 trigger 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 
 obtain power headroom information for each activated cell, if extended PHR is used and an uplink resource is allocated for new transmission. 
   
     
     
       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. 
     
     
       10. The UE of  claim 9 , wherein if the indicator is 0 the indicator indicates the first type maximum transmit power information, and
 wherein if the indicator is 1 the indicator indicates the second type maximum transmit power information.   
     
     
       11. A method for receiving power headroom information by a base station in a communication system, the method comprising:
 transmitting 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); and   receiving a power headroom information for each activated cell from the terminal,   wherein a power headroom report (PHR) for the power headroom information is triggered 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.   
     
     
       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 the power headroom information for each activated cell and an indicator for maximum transmit power information.   
     
     
       15. The method of  claim 14 , wherein if the indicator is 0 the indicator indicates the first type maximum transmit power information, and
 wherein if the indicator is 1 the indicator indicates the second type maximum transmit power information.   
     
     
       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 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), and 
 receive a power headroom information for each activated cell from the terminal, 
   wherein a power headroom report (PHR) for the power headroom information is triggered 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.   
     
     
       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. 
     
     
       20. The base station of  claim 19 , wherein if the indicator is 0 the indicator indicates the first type maximum transmit power information, and
 wherein if the indicator is 1 the indicator indicates the second type maximum transmit power information.   
     
     
       21. A method for obtaining, by a user equipment (UE), power headroom information in a communication system, the method comprising:
 acquiring information for a power headroom report (PHR) associated with a multiple cells;   acquiring information for a path loss reference based on a second cell configuration, wherein the information for the path loss reference indicates a cell which the UE applies as the path loss reference;   triggering the PHR in case that 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;   obtaining power headroom information for each activated cell configured with uplink (UL), in case that an uplink resource is allocated for new transmission; and   generating a medium access control (MAC) protocol data unit (PDU) including the power headroom information for each activated cell with configured UL and an indicator for each activated cell with configured UL,   wherein the indicator indicates whether the power headroom information is based on a real physical uplink shared channel (PUSCH) transmission or a PUSCH reference format,   wherein, in a case that the power headroom information is based on the real PUSCH transmission, the power headroom information is obtained based on a parameter related to a number of resource blocks and a parameter derived from modulation and coding scheme (MCS), and   wherein, in case that power headroom information is based on the PUSCH reference format, the parameter related to the number of resource blocks and the parameter derived from MCS are set to 0, zero power back-off is considered and the power headroom is obtained based on a maximum uplink transmission power equal to one of a maximum allowed UE output power (P EMAX ) and a nominal UE power (P powerclass ).    
     
     
       22. The method of  claim 21 , wherein a path loss reference for a first cell is the first cell and a downlink of the second cell corresponding to an UL of the second cell is indicated by adding the second cell.  
     
     
       23. The method of  claim 21 , wherein the power headroom information for each activated cell with configured UL is multiplexed with higher layer data.  
     
     
       24. The method of  claim 21 ,
 wherein in case that the indicator is 0 the indicator indicates the real PUSCH transmission, and   wherein in case that the indicator is 1 the indicator indicates the PUSCH reference format.    
     
     
       25. A method performed by a base station for power headroom information in a communication system, the method comprising:
 transmitting, to a user equipment (UE), information for a power headroom report (PHR) associated with multiple cells and information for a path loss reference based on a second cell configuration, wherein the information for the path loss reference indicates a cell which the UE applies as the path loss reference; and   receiving, from the UE, a medium access control (MAC) protocol data unit (PDU) including power headroom information for each activated cell with configured uplink (UL) and an indicator for each activated cell with configured UL,   wherein the indicator indicates whether the power headroom information is based on a real physical uplink shared channel (PUSCH) transmission or a PUSCH reference format,   wherein, in a case that the power headroom information is based on the real PUSCH transmission, the power headroom information is obtained 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 power headroom information is based on the PUSCH reference format, the parameter related to the number of resource blocks and the parameter derived from MCS are set to 0, zero power back-off is considered and the power headroom is obtained based on a maximum uplink transmission power equal to one of a maximum allowed UE output power (P EMAX ) and a nominal UE power (P powerclass ).    
     
     
       26. The method of  claim 25 ,
 wherein, a path loss reference for a first cell is the first cell and a downlink of the second cell corresponding to an UL of the second cell is indicated by adding the second cell,   wherein the PHR is triggered by the UE, in case that 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   wherein the power headroom information for at least one activated cell configured with UL is obtained by the UE, in case that an uplink resource is allocated for new transmission and the PHR for the multiple cells is configured.    
     
     
       27. The method of  claim 25 ,
 wherein the power headroom information for each activated cell with configured UL is multiplexed with a higher layer data.    
     
     
       28. The method of  claim 25 ,
 wherein in case that the indicator is 0 the indicator indicates the real PUSCH transmission, and   wherein in case that the indicator is 1 the indicator indicates the PUSCH reference format.    
     
     
       29. A user equipment (UE) for power headroom information in a communication system, the UE comprising:
 a transceiver; and   a controller configured to:
 acquire information for a power headroom report (PHR) associated with multiple cells, 
 acquire, via the transceiver, information for a path loss reference based on a second cell configuration, wherein the information for the path loss reference indicates a cell which the UE applies as the path loss reference, and 
 trigger the PHR in case that 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, 
 obtain power headroom information for each activated cell configured with uplink (UL), in case that an uplink resource is allocated for new transmission, and 
 generate a medium access control (MAC) protocol data unit (PDU) including the power headroom information for each activated cell with configured UL and an indicator for each activated cell with configured UL, 
   wherein the indicator indicates whether the power headroom information is based on a real physical uplink shared channel (PUSCH) transmission or a PUSCH reference format,   wherein, in a case that the power headroom information is based on the real PUSCH transmission, the power headroom information is obtained based on a parameter related to a number of resource blocks and a parameter derived from modulation and coding scheme (MCS), and   wherein, in case that power headroom information is based on the PUSCH reference format, the parameter related to the number of resource blocks and the parameter derived from MCS are set to 0, zero power back-off is considered and the power headroom is obtained based on a maximum uplink transmission power equal to one of a maximum allowed UE output power (P EMAX ) and a nominal UE power (P powerclass ).    
     
     
       30. The UE of  claim 29 ,
 wherein a path loss reference for a first cell is the first cell and a downlink of the second cell corresponding to an UL of the second cell is indicated by adding the second cell.    
     
     
       31. The UE of  claim 29 ,
 wherein the power headroom information for each activated cell with configured UL is multiplexed with a higher layer data.    
     
     
       32. The UE of  claim 29 ,
 wherein in case that the indicator is 0 the indicator indicates the real PUSCH transmission, and   wherein in case that the indicator is 1 the indicator indicates the PUSCH reference format.    
     
     
       33. A base station for power headroom information in a communication system, the base station comprising:
 a transceiver; and   a controller configured to:
 transmit, to a user equipment (UE) via the transceiver, information for a power headroom report (PHR) associated with multiple cells and information for a path loss reference based on a second cell configuration wherein the information for the path loss reference indicates a cell which the UE applies as the path loss reference, and 
 receive, from the UE via the transceiver, a medium access control (MAC) protocol data unit PDU including power headroom information for each activated cell with configured uplink (UL) and an indicator for each activated cell with configured UL, 
   wherein the indicator indicates whether the power headroom information is based on a real physical uplink shared channel (PUSCH) transmission or a PUSCH reference format,   wherein, in a case that the power headroom information is based on the real PUSCH transmission, the power headroom information is obtained based on a parameter related to a number of resource blocks and a parameter derived from modulation and coding scheme (MCS), and   wherein, in case that power headroom information is based on the PUSCH reference format, the parameter related to the number of resource blocks and the parameter derived from MCS are set to 0, zero power back-off is considered and the power headroom is obtained based on a maximum uplink transmission power equal to one of a maximum allowed UE output power (P EMAX ) and a nominal UE power (P powerclass ).    
     
     
       34. The base station of  claim 33 ,
 wherein a path loss reference for a first cell is the first cell and a downlink of the second cell corresponding to an UL of the second cell is indicated by adding the second cell,   wherein the PHR is triggered by the UE, in case that 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   wherein the power headroom information for at least one activated cell configured with UL is obtained by the UE, in case that an uplink resource is allocated for new transmission and the PHR for the multiple cells is configured.    
     
     
       35. The base station of  claim 33 ,
 wherein the power headroom information for each activated cell with configured UL is multiplexed with higher layer data.    
     
     
       36. The base station of  claim 33 ,
 wherein in case that the indicator is 0 the indicator indicates the real PUSCH transmission, and   wherein in case that the indicator is 1 the indicator indicates the PUSCH reference format.