How SN status transfer works in UM mode during handover?

Question

I would like to ask the following:
1.How UE will be effected
2.How Source eNodeB will be effected
3.How about the re-transmission of PDCP(SN), PDCP (NO SN)

Thanks.

Answer 1

As per my understanding, source eNodeB executes SN status transfer procedure for the bearers which come under the PDCP status reservation (RLC AM mode). PDCP status of each bearer (with RLC AM mode) should be transferred from source eNodeB to target eNodeB. Target eNodeB RLC entity may use for the re-transmission during the re-establishment. This is done to avoid application level re-transmission.
I never seen this message to be exchanged between source and target eNodeBs when only UM mode bearers are established. I am talking about the lab environment. In reality, default bearer (QCI-9) would be present and it is an AM mode bearer.
Waiting for others to respond.

Comments

i think no use of transferring SN status to src to tar enb in UM mode.