Various apparatuses and methods for transmitting uplink data of an application at a user equipment are provided. In one aspect of the disclosure, uplink data of an application at a user equipment (UE) is transmitted to a network. A first amount of the uplink data expected to be buffered at a radio link control (RLC) layer is determined based on a latency of the application. A second amount of the uplink data available for transmission at the RLC layer is determined based on information provided by a modem of the UE. A data rate of the application is dynamically adjusted based on a difference between the first amount and second amount of the uplink data. In another aspect of the disclosure, an amount of the application data buffered at the RLC layer is maintained to be greater than a predetermined threshold that sets a Happy bit at an unhappy setting. The unhappy setting is communicated to the network, a data rate of the application is increased in response to an increased grant from the network due to the unhappy setting. In another aspect of the disclosure, a maximum modem supported data rate at which the user equipment (UE) transmits uplink data of an application is determined based on an uplink channel capacity estimate, a modem queue length estimate, a codec rate change frequency of the application, and a delay threshold of the modem queue.