Wireless User Equipment (UEs) are adapted to facilitate uplink transmissions on two or more carriers. According to one example, a wireless user equipment can determine whether a size of data to be transmitted is greater than or less than a predetermined threshold. When the size of the data is less than the predetermined threshold, the wireless user equipment can transmit the data on a primary carrier. When the size of the data is greater than, or equal to the predetermined threshold, the wireless user equipment can transmit an initial portion of the data on the secondary carrier, and any remaining portion of the data can be transmitted on the primary carrier. Other aspects, embodiments, and features are also included.