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Handover
Posted on 22. Oct, 2012 by rajilm
in LteWorld Forum
Hi all,
can any one tell me
what are the conditions have to check for the handover in eNB?
why A4 A5 events r required?
on what basis UEi is sending measurement report to enb?
Handover Trigger
At UEi, measurements could trigger based on events, as per 36.331 A4/A5 definitions are below. As name suggest these events trigger measurements that are reported to eNB.
Event A4 (Neighbour becomes better than threshold)
Event A5 (Serving becomes worse than threshold1 and neighbour becomes better than threshold2)
Measurement report triggering by UE could be periodic or based on events (see 5.5.4 of 36.331)
Once eNB has the report it may trigger Handoveri. 36.300 states that in connected mode, Handover decisions may be based on UE and eNB measurements. In addition, handover decisions may take other inputs, such as neighbour cell load, traffic distribution, transport and hardware resources and Operator defined policies into account.
At eNB you have parameter/thresholds defined. eNB compares the received fields in measurement report with data that is provisioned and based on that it may or may not trigger handover. Refer 36.331 for MeasResults information elements.
ok sir, now pls tell me what
ok sir, now pls tell me what u mean by absolute threshold1 & absolute threshold2 in A5 event
Ok sir, but pls tell me what
Ok sir, but pls tell me what is the difference between threshold1 and threshold2 in A5.
Same RRCi spec defines
Same RRCi spec defines following
Thresh1 is the threshold parameter for this event (i.e. a5-Threshold1 as defined within reportConfigEUTRA for this event).
Thresh2 is the threshold parameter for this event (i.e. a5-Threshold2 as defined within reportConfigEUTRA for this event).
reportConfigEUTRA definition is below. These thresholds need to be set by eNB. These are for different comparisons one for serving while other for neighbor.
aN-ThresholdM
Threshold to be used in EUTRA measurement report triggering condition for event number aN. If multiple thresholds are defined for event number aN, the thresholds are differentiated by M.
Hope it is clear now.