A method includes (1) receiving with a user equipment (UE) information related to an allowed power for autonomous transmission on at least one logical channel mapped to an uplink channel, the uplink channel being set up with a base station and dedicated for packet data transmission, (2) determining, with the UE and in accordance with a scheduling grant received from the base station, an allowed power of scheduled transmission on the uplink channel, (3) determining a total data amount allowed to be transmitted, (4) determining a data amount for the autonomous transmission on the logical channel, the determined autonomous transmission data amount being not greater than an allowed autonomous transmission data amount corresponding to the allowed autonomous transmission power, and (5) determining a data amount for scheduled transmission on the logical channel, the determined scheduled transmission data amount being not greater than an allowed scheduled transmission data amount corresponding to the allowed scheduled transmission power.