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How Drx configuration is usefull for UE to perform ECGI measurement ? [CLOSED]

+2 votes

According to 3Gpp spec 36.331 for EUTRA , in RRC measurement configuration if purpose set to REPORTCGI, then T321 timer will be set to 1 sec.

If this is the case then where UE will use this Drx configuration? Please can any one explain me this...

closed with the note: None
posted May 13, 2014 by Bheemappa G

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Help me and Help yourself. You are asking that how Discontinuous reception is useful in case of cell measurements. But as i know DRx is totally different funda in LTE, GSM as well as in UMTS. I am aware up to UMTS if in LTE it has some different purpose then i request you to explain it more. Well I will explain the DRx below in answer. If you will have different query you can cross comment on that.

2 Answers

+3 votes

@Hiteshwar: What you have written is right but in LTE as you know it is self optimized network. So the thing is UE has to send the measurements reports of serving cell as well as for neighbor cells, but when you are connected to one EARFCN how can you calculate the neighbor measurements. Therefore in LTE it is using as measurement gaps to do these measurements.

Measurement Gaps are periods where UE switches off its Rx and TX from the serving Cell and starts listening to other. This GAP period has to be in sync with the eNB because the eNB should know when the UE will enter the GAP state. To configure the GAP period in UE, eNB uses measGapConfig IE which is included in RRCConnectionReconfiguration message.

UE will use the Discontinuous reception for measurements. In this perios eNodeB will not grant any UL data and will not send any downlink data.

@Bheemesh: how it is useful that this is the only reason. DTx and DRx are measurement gaps used for the these reporting and all. Before LTE the purpose was only one and now it has more reasons.
and T321 timer is for UE to get the SIB1 information from neighbor cell and report it. It is also possible that if UE is not getting SIB info within timer expires eNodeB can relase the DRx mode.

answer May 14, 2014 by Sidharth Malhotra
+1 vote

DRX (Discontinuous Reception):

To save the power problem of UE side the network will inform the UE that you can sleep till this time, you don't have any updates from network till this time. Get awake after this time. This info can be send by RRCConnectionReconfiguration or in RRCSetup message also. This is how UE can save the energy and resources. It can extend the UE battery life. In one line UE turn off the radio receiver for some time and goes to sleep.

Thought LTE has always on feature but this is an acceptable situation and can be find out in lot of scenarios. now Does it have any relation with measurements then please educate me.

answer May 14, 2014 by Hiteshwar Thakur
Yes it does have relation with measurement ....especially when you are doing CGI measurement you require long DRX to be active and provide higher value which helps UE in reading CGI Info on neighbor cell
The higher value for DRX in UE Test Spec Suggest the same....
36.523-1 Rel 9 versiobn 9.8.0
Table RadioResourceConfigDedicated-DRX (step 5, Table
RadioResourceConfigDedicated-DRX ::=
mac-MainConfig CHOICE {
explicitValue SEQUENCE {
ul-SCH-Config SEQUENCE {
maxHARQ-Tx n5
periodicBSR-Timer infinity
retxBSR-Timer sf10240
ttiBundling FALSE
drx-Config CHOICE {
setup SEQUENCE {
onDurationTimer psf6
drx-InactivityTimer psf60
drx-RetransmissionTimer sf16
longDRX-CycleStartOffset CHOICE {
sf1280 4
shortDRX Not present
timeAlignmentTimerDedicated infinity
phr-Config CHOICE {
release NULL
physicalConfigDedicated Not present
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+2 votes

I have two cells having same operating frequency with different PCI's. After applying measurement config I got neighbor cell measurement report and then I am triggering for ECGI request but I am not getting ECGI report.

So I am guessing there is problem in configuration of DRX which is used to give proper idle period to UE.

Please help if any one have experience on this.

+4 votes

Suppose i want to Intra frequency measurement .

ENB1 - Freq - 1000 (PCI - 2)
ENB2 - Freq - 1000 (PCI - 5)

So how can i configure the Measurement config ???

+4 votes

I have gone through the measurement config/ report messages.I found that in meas report UE can send PCI, RSRP, RSRQ, CGI report at a time.

Will UE will send CGI report also at the same time or UE will send only when ENB request UE for the ECGI with the Report ECGI by giving pci ?