volte trouble shooting in ericsson lte rtt

8/9/2019 VoLTE Trouble Shooting in Ericsson LTE RTT

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VoLTE Trouble Shooting in Ericsson LTE RTT.Below are some samples of using RTT to troubleshoot VoLTE failures.

IMSI = 311!"1#$$%# on 'ate = 1"(#)(#"1.1) Example of how a Good VoLTE call will loo in E!!! RTT.

*or a su++essful VoLTE +all there is normall, at -oo 'ei+ate Bearer an a -oo/onte0t.

The Bearer is SS=1) an is the length of the VoLTE +all whi+h is #%.&33 se+ons inthe s+reen shot abo2e.

The -oo /onte0t is from RR/ Setup to /onte0t Release an normall, starts beforethe Bearer an ens after the Bearer.If the -oo /onte0t starts right before the VoLTE Bearer ,ou +an use this toguestimate if the VoLTE +all was a Termination or rigination.

") This is an example of a VoLTE L# for a short VoLTE #all with $L R%&ssues.

The VoLTE Bearer is still liste as a V-oo /all be+ause the MME(S-4 tears ownthe +all in a normal manner. It oes not ini+ate to E/'S that the Bearer was tornown ue to an R* *ailure.

That t,pe of message is not pro2ie an is wh, the Bearer is still liste as a VoLTE-oo.

The VL/ o++urs at roughl, e0a+tl, the same time the V-oo an the VL/ is the R*re+or from E/'S. 5o2ering o2er the /onte0t Release reasons pro2ie this etail6E Release /ause = 11 = Raio /onne+tion with 6E Lost. Internal /ause = 1 =RR/ Re+on7guration Time out.Both these simpl, ini+ate that the R* +onition was ba. 4hen I right8+li+9e ani a 5ano: ;opup there was no hano: for this +all.4hen ,ou loo9 at the ne0t few -oo /onte0t re+ors the, are all on 1&3.3.# at".%3(".&! miles awa,.


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If I loo9 at the Right8/li+9 6E 'ata ;opup for some of the other -oo /onte0t afterthe VL/ I +an see .I also see that 6L ?a9> = #).%> an 6L BLER> = 31."> an 6L 9bps = #&.

This ini+ates to me that the mobile 6plin9 was in a ba R* +onition.

The last thing to note that tens to ini+ate this was a ba VoLTE +all is that for theV-oo 'ei+ate Bearer re+ors the S-4 B,tes R0e in the 6L is ".I ha2e seen in the past on some one8wa, auio that I ha that the /I=1 Bearerre+or ha either 6L or 'L S-4 B,tes = ". This is not a 1""> ini+ator that a onewa, auio o++urre but it is a goo sanit, +he+9.


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') ( single VoLTE #all with multiple VL# in it.

In the abo2e s+reen shot the VoLTE /all starts at 1%@$@"1.% an ens at 1&@"3@".$as seen in row 1$ V-oo Bearer re+or.4e see one VL/ at 1%@$)@3% Arow 1& an another at 1&@"3@"$.# Arow 11. TheVL/ at 1&@"3@"$.3 is Release 6E /ause = 11 = Raio /onne+tion with 6E lost anInternal Reason = % = RL/ *ailure on Signaling Bearer.

To me this ini+ates that the VoLTE /all ene with a rop sin+e the VL/ is at thesame time of the Bearer En Time.

The VL/ that o++urs at 1%@$)@3% is in the mile of the VoLTE +all. This ini+ates tome that the R* /onte0t was Release but i not +ause the VoLTE Bearer to berelease.Sin+e this VL/ was in the mile of the VoLTE +all it li9el, +ause some auio holes

while the Raio /onte0t was release an re8establishe.?ote@ The Subs+riber ?umber is not populate in all the E/'S re+ors. If ,ou onl,ha2e the Subs+riber sear+h that 7rst an then re8Cuer, with the IMSI to ma9e sure,ou ha2e all the re+ors.

) VoLTE Setup %ail *VS%) example.


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RTT +an onl, +apture some of the VS* +alls. In the +ase below there is an ER


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,) #reating a -istance istogram for all the VL# and VS% and plotting

them on a map. The 'istan+e 5istogram page +an be use ust to loo9 at the VL/ an VS*. This isone b, onl, +he+9ing VS* an VL/ when running the Cuer,.In the s+reen shot below I Cuerie the last ! a,s of VL/ an VS* an it onl, too91% se+ons to run for &!!$ VL/ an VS* that ha 'istan+e information. AVoLTEF/at7el is ine0e.I then sorte b, Total /ount an foun that $&.$).1# ha the most VL/(VS* at 1&3.I then right8+li+9e on that row of ata an +hose GShow /all Lo+ations on Map ;op8upH.


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The 'istan+e 5istogram for the VS*(VL/ are then plotte on the Map ;op. Dou +anopen multiple Map ;opups at a time but right8+li+9ing on a new row of ata.


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/) 0lotting where the VL# and VS% are occurring with Simple uer2 page.Sin+e we are still in earl, stages of VoLTE in most mar9ets ,ou +an Cuer, the last !a,s of all VL/ an VS* in the Simple uer, page.

Then ,ou +an right8+li+9 on the results table an +hoose GShow /all Lo+ation on Map;opupH.In LTE RTT we onl, get the 'istan+e measurement for one M9t.e?B./ellFI' an

ispla, this as an ar+ on the map. The +ount of re+ors at that istan+e is ispla,ein te0t at the +enter aimuth of the se+tor.In the s+reen shot below I oome into an area of interest on the map an +hangethe


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In +ontrast I +an turn o: the 5eat Map option an reu+e the Thi+9ness to 1">. This ma9es ea+h ar+ rawn at 1""> transparen+,.

$pdate3 The Session Status4"" were remo5ed from the VL# formulaon 1!"1!"61 to match the EL0T VL# formula.


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LTE RTT Release V+. 1!"1!"61 at /366pm Eastern #hange#ontrol 4 7##666666',11/89) VL# with Session Status 4 "" 4 ER(: Release with -ata Lost.

This is a new VL/ introu+e in E((( RTT +tober #"1 with the upgrae to E/'S$..1. This was ae to mat+h the EL;T VL/ formula this it@ApmErabRel

volte trouble shooting in ericsson lte rtt

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