Enhanced Fast Dormancy Feature Relation with 4B Event
Intrnal
Case Title: Enhanced Fast Dormancy Feature Relation with 4B
EventAuthorVladimir Petrov 85349
Date08.11.2012
Product & VersionRNC: BSC6900 V900R013C00SPH556
Phenomenon DescriptionOur customer reported that there is
discrepency between expected and actual Fast Dormancy UE behaviour
upon receiving 4B event in regards to our HedEx documentation.
Alarm InformationFrom below picture and the explanation for fast
dormancy transition taken from Hedex, one of the requirements for
Cell-DCH->Cell-FACH or Cell-Fach->Cell-PCH reconfiguration is
receiving of event 4B from the UE.
However during tests it was found that 4B event doesnt trigger
F2P transition as expected.
As we can see we have a UE in FACH state which sends 4B event
but the RNC doesnt send RRC_RB_RECFG_REQ to order the UE to go to
PCH state.
AnalysisBackground:
1. PsInactTmrForFstDrmFach is 10s (FAST DORMANCY USER T1 in
CELL_FACH)
2. BeF2PStateTransTimer is 17s (BE FACH or E_FACH to PCH
Transition Timer)
F2PTvmTimeToTrig is D5000 (BE F2P 4B Time)
F2PTvmPTAT is D250 (BE F2P 4B Pending Time)
StateTransTraffRedundCoef is 80 (Redundancy Coeff for State
Transition)
We have analyzed the traces provided by our customer from their
tests and we have isolated two typical scenarios
Case 1 - TIME: 17:27:45 (63) to 17:27:56 (33)
When the timer of PsInactTmrForFstDrmFach goes over 10, and
there is no L2 data transmission F2P will be executed according to
our customer expectations:
Case 2 - TIME: 17:24:40 (76) to 17:25:56 (67)
We can see that there is some data transmission from 17:24:41
(37) to 17:24:51 (67) so PsInactTmrForFstDrmFach timer is reset
each time data transmission ends
However for the BeF2PStateTransTimer timer duration (17s) we see
UE reporting 2 uplink 4B events, 3 downlink 4B events (totally 5 4B
events) and then the UE goes to PCH
Reason for this behavior is D2F2PTvmThd (BE D2F/R or F/R2P 4B
Threshold)
D2F2PTvmThd = [ BeF2PStateTransTimer / (F2PTvmTimeToTrig+
F2PTvmPTAT) * StateTransTraffRedundCoef ]
Based on the following parameter configuration:
BeF2PStateTransTimer - 17sF2PTvmTimeToTrig - D5000msF2PTvmPTAT -
D250msStateTransTraffRedundCoef - 80%We receive:D2F2PTvmThd =
17/(5+0.25)*0.8 = 2 /round down to closest integer value/. As a
result we can see that we need 2x4B events to trigger F2P
transitionPlease note that1. In RAN13 and RAN14 we have two
different rules regarding state transition
a) RAN13:The number of UL and DL 4B events (each) should be
above the F2P transition threshold before the timer expires,
b) RAN14: The number of UL and DL 4B events (sum) should be
above the F2P transition threshold before the timer expires
2. Downlink 4b events are reported by MACD as follows:
Unfortunately Huawei documentation is not specifying any details
for Downlink 4B events and its impact upon UE state transition.
SolutionOur analysis shows that UE state transition is not only
related with Uplink 4B event but also by Downlink 4B event which is
reported on MAC layer
Suggestion and SummaryWe have initiated RM flow for document
improvement: add in HedEx information for Downlionk 4B event and
its impact upon UE state transition algorithms
ReferenceN/A
2012-11-20HUAWEI ConfidentialPage1, Total4
