Understanding LTE Model Internals and Interfaces
Understanding LTE Model Internals and Interfaces
Understanding LTE Model Internals and Interfaces
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1581 <strong>Underst<strong>and</strong>ing</strong> <strong>LTE</strong> <strong>Model</strong> <strong>Internals</strong> <strong>and</strong> <strong>Interfaces</strong>The R<strong>and</strong>om Access Procedure•All UEs use it for initial attachment•UEs without PUCCH allocation use it for sending b<strong>and</strong>widthrequests•Implemented in lte_rach.pr.m, a child process of lte_ue_as.pr.m•Exchange of 4 messages between the UE <strong>and</strong> the eNodeB• msg1 or preamble: UE sends to the eNodeB (lte_rach process model)• msg2 or the r<strong>and</strong>om access response: eNodeB sends to the UE• Function lte_enb_as_r<strong>and</strong>om_access_responses_generate() inlte_enb_as.pr.m• Message carries an uplink grant within itself• msg3: UE sends to the eNodeB from lte_rach process• Uses the UL grant that comes with the r<strong>and</strong>om access response message• Has HARQ support• msg4 or the contention resolution message: terminates the r<strong>and</strong>om accessprocedure successfullyCONFIDENTIAL ─ RESTRICTED ACCESS: This information may not be disclosed, copied, or transmitted in any format without the prior written consent of OPNET Technologies, Inc. © 2010 OPNET Technologies, Inc.63
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