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LTE: When Contention Free RACH procedure will fail?

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At handover time target ENB will give rach preamble to UE. Is it necessary that target ENB is to be sink with source ENB. How UE will do contention free rach when both or not in sink? Is their any case Contention free rach will fail?

posted Jul 29, 2015 by anonymous

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1 Answer

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On behalf of Venumadhav Josyula

Contention free RACH is designed such that enodeB accolate dedicated preambles for UEs such that there is absolutely not possibility of collisions. So it will never fail under decent radio conditions. So according to me it should will never fail ... :) faulty UE or enobeB does not guarantee it...

answer Jul 29, 2015 by Salil Agrawal
Their should be sink between two ENB's (source and target)? Is it needed?
I am also facing the same problem...
Because in our case both Enbs are in sync with GPS but UE is still failing to do the contention free rach on the dedicated  preamble and prach config index given by source ENB, So what could be the possible reason for contention free rach failure???
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