Some aspects of the disclosure provide a method of data transmission. In some examples, a synchronization relationship among a plurality of quality of service (QoS) flows is recognized. When the synchronization relationship among the plurality of QoS flows is recognized, a synchronization parameter associated with the plurality of QoS flows is obtained. When a network transmission quality indicates a need for packet discarding, at least a target QoS flow in the plurality of QoS flows that fails to satisfy a synchronization requirement to other QoS flows in the plurality of QoS flows is selected based on the synchronization parameter. At least a target data packet in the target QoS flow is discarded. Apparatus and non-transitory computer-readable storage medium counterpart embodiments are also contemplated.