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

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 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, if extended PHR is used and 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 and an indicator for each activated cell,
• wherein the indicator indicates whether power headroom information is based on a real physical uplink shared channel (PUSCH) transmission or a PUSCH reference format.

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 medium access control (MAC) protocol data unit (PDU) including the power headroom information for each activated cell and an indicator for maximum transmit power information,
• wherein a power headroom report (PHR) for the power headroom information is triggered if 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 indicator indicates whether power headroom information is based on a real physical uplink shared channel (PUSCH) transmission or a PUSCH reference format.

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 medium access control (MAC) protocol data unit (PDU) including the power headroom information for each activated cell and an indicator for maximum transmit power information,
• wherein a power headroom report (PHR) for the power headroom information is triggered if 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 indicator indicates whether power headroom information is based on a real physical uplink shared channel (PUSCH) transmission or a PUSCH reference format.