LTE : What is NAS recovery procedure ?

Question

I am not able to find NAS Recovery message as such in 24.301 spec. Some weblink has talked about NAS recovery but I could not any reference in specification.
Would someone like to put some comment on this topic ?

Answer 1

Consider this Scenario -

1. ENB A Given Measurement Configuration to a UE and due to RLF Happened with UE so UE not sent measurement Report.
2. UE will try to re-establish with other ENB (suppose ENB - B) nearer to him so he UE will send RRC Re-establishment message to ENB B , But at ENB B there is no context about this (As measurement report not reached and handover preparation also not sent from ENB A to ENB B)
3. So here two case arises
   CASE 1: Either ENB B will bring context from ENB A (Known as Forward Handover procedure) and Proceed with re-establishment procedure .
   CASE 2: ENB B will send RRC Establishment Reject (As he is not able to find context of UE at ENB B and unable to get context from ENB A) . so UE will go to idle mode and later UE will start from beginning by synchronizing with the ENB B. In this case all older data of UE present at ENB A will be lost .
   This is known as NAS Recovery Procedure.

Reference :-
http://www.faqs.org/patents/app/**********
http://www.google.co.in/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&ved=0CCoQFjAA&url=http%3A%2F%2Fwww.qualcomm.com%2Fmedia%2Fdocuments%2Ffiles%2Flte-mobility-enhancements.pdf&ei=D9sOU9-wMITtrAegtIHoBw&usg=AFQjCNH3NukQA02YEM6fjgFZQYcOAkbqIA&sig2=IRJRb0bXkYi0tGgZ4OU40w&bvm=bv.61965928,d.bmk&cad=rja

Comments

In that scenario, What UE shall do ? Does it maintain all previous session ?  What shall be impact of running data with respect to UE and Network ?

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UE will only contain RLF report when RLF happened, When UE gets RRC Reestablishment then in reestablishment complete UE will tell that i have RLF report then ENB can ask for it and find out the reason of RLF for it.