Power headroom report generation

An apparatus comprising:

• a processor that:
• aggregates multiple serving cells;
• and
• determines that a power headroom report is triggered;
• a receiver that receives, at a time after the power headroom report is triggered, an uplink grant that allocates uplink resources for an initial transmission, wherein:
• the processor:
• determines whether a power headroom report for an activated serving cell is based on a real or a reference physical channel uplink shared channel transmission;
• in response to determining that the power headroom report for the activated serving cell is based on the reference physical uplink shared channel transmission, computing a power headroom value for the activated serving cell of the multiple serving cells based on the reference physical uplink shared channel transmission, wherein the power headroom value is computed using a predefined set of power control parameters;
• and
• generates a power headroom report medium access control control element comprising the power headroom value for the activated serving cell;
• and
• a transmitter that transmits the power headroom report medium access control control element on the uplink resources allocated by the uplink grant.

An apparatus comprising:

• a processor that determines that a power headroom report is triggered;
• and
• a receiver that:
• receives, at a time after the power headroom report is triggered, a first uplink grant that allocates first uplink resources for transmitting a power headroom report medium access control control element;
• and
• receives a second uplink grant that allocates second uplink resources for an uplink transmission, wherein the second uplink resources are in a same transmission time interval as the first uplink resources, wherein the processor ignores the second uplink grant.