The 5G radio access network (RAN) architecture is supposed to be split into the central unit (CU) and the distributed unit (DU) in order to support more flexible transport networks and provide enhanced user experience. However, such functional split may also introduce some new technical issues. In this paper, we study the data fast retransmission issue introduced by this functional split in different scenarios and solutions are provided to handle this issue. With the fast data retransmission mechanism proposed in this paper, the retransmitted data packets could be identified and handled with high priority. In this way, the data delivery between the CU and DU in 5G RAN is assured.
5G RAN; central unit; distributed unit; fast retransmission