FIG. 4 is a diagram illustrating a wireless protocol structure of a next generation mobile communication system according to an embodiment of the disclosure.
Referring to FIG. 4, a wireless protocol of the next generation mobile communication system may include NR service data adaptation protocols (SDAPs) 4-01 and 4-45, NR PDCPs 4-05 and 4-40, NR RLCs 4-10 and 4-35, and NR MACs 4-15 and 4-30 in a terminal and an NR base station, respectively.
Main functions of the NR SDAPs 4-01 and 4-45 may include some of the following functions.
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        - Transfer of user data (transfer of user plane data)
- Mapping between a QoS flow and a data bearer for uplink and downlink (mapping between a QoS flow and a data radio bearer (DRB) for both DL and UL)
- Marking QoS flow ID in DL and UL (marking QoS flow ID in both DL and UL packets)
- Mapping a reflective QoS flow to a data bearer with respect to UL SDAP PDUs (reflective QoS flow to DRB mapping for the UL SDAP PDUs)