LTE: Why UE does not "attach complete" message along with "RRC Connection Reconfiguration Complete" ?

Question

During attach procedure, UE sends "Attach Request" along with "RRC Connection Setup Complete", eNodeB sends "Attach Accept" along with "RRC Connection Reconfiguration then why UE does not send "Attach Complete" along with "RRC Connection Reconfiguration Complete" message ? What could be the reason for defining the messages so ?

Answer 1

Before srb2 configuration, nas messages are transferred with srb1. Srb2 is configured after security activation during RRC connection reconfiguration. so attach complete message is send with srb2

Comments

Thanks Veer to provide a logical reason. However I am not 100% sure SRB2 is an optional or mandatory signalling radio bearer. I posted another query lets see what response comes from professionals. I would also appreciate for your response.

Answer 2

Hello, RRC connection establishment is done by dci (it carrier only scheduling information) in PDCCH. So the point is dci carries only scheduling information but does not carry data.

Comments

Hi Balagopal thanks to share your inputs.

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