ERAB AbRelease Causes Correct

 

E-RAB Abnormal Release Causes

HUAWEI TECHNOLOGIES CO., LTD. HUAWEI TECHNOLOGIES CO., LTD.

Huawei Confidential

 

Contents •

•

Counters names & description Abnormal Releases causes mapping

•

Difference between E-RAB Release & UE Context C ontext release Command messages

•

Types of Normal Releases.

•

Abnormal Releases causes Measurement points  –

MME

 –

Radio

 –

TNL

 –

HO failure

 –

•

Congestion Examples Examp les from Nastar for some ERABA ERABAbnorma bnormall relea releases ses

•

Queries Queri es about ERA ERABAbnor BAbnormal mal Relea Release se due to load.

HUAWEI TECHNOLOGIES CO., LTD.

Huawei Confidential

Page 2

 

Counters names & description and related KPI

The counters measure the number of abnormal E-RAB releases due to different causes in a cell. An E-RAB is the access layer bearer for carrying service data of users. The E-RAB release is a process of releasing the access layer bearer resources of users



Total

no. of Abnormal release affect on call drop rate KPIs

HUAWEI TECHNOLOGIES CO., LTD.

Huawei Confidential

Page 3

 

Abnormal Releases causes mapping

UE

MME/SGW

E-RAB E-NodB

E-RABAb E-RA BAbnorma normall Rel.C Rel.Cong. ong.** E-RABAb E-RA BAbnorm normal al Rel.H Rel.HOfail Ofail E-RABAb E-RA BAbnorm normal al Rel.R Rel.Radio adio

•

E-RABAb E-RA BAbnorm normal al Rel.T Rel.TNL NL

E-RABAb E-RA BAbnorma normall Rel. Rel.MME MME

* ERABAbnormal release due to congestion can be mainly due to radio resources congestion but i am not sure if it doesn't include other entities congestion ( transmission & MME )

HUAWEI TECHNOLOGIES CO., LTD.

Huawei Confidential

Page 4

 

Difference between E-RAB Release & UE Context release •

E-RAB RELEASE COMMAND •

•

Only will to release the RAB/s with the mentioned ID/s so in case of a UE having more than one RAB it will not release all its RABs only the mentioned IDs

UE Context RELEASE COMMAND •

Will release all RABs allocated to this UE and the same if multiple number of UEs are mentioned in the message

Types of Non-exception E-RAB releases initiated by the MME • • • •

Normal Release. Release. Detach User Inactivity CS fallb fallback ack trigge triggered red

HUAWEI TECHNOLOGIES CO., LTD.

Huawei Confidential

Page 5

 

E-RABA bnorma rmall Re Rel.M l.MME ME s two tri trigge ggerin ring g msgs. msgs. E-RABAbno ’

•

E-RAB RELEASE COMMAND  As

in figure 1 the L.E-RAB.AbnormRel.MME L.E-RAB.AbnormRel.MME counter is incremented each each time the E-RAB release is initiated by the MME and the eNodeB receives an E-RAB RELEASE COMMAND message from the MME and the Release Cause information element is not Normal Release, Release, Detach Detach,, User Inactivity, Inactivity, or cs fallback fallback triggered triggered.. If the E-RAB RELEASE COMMAND message requires multiple E-RAB releases at the same time, the L.E-RAB.AbnormRel.MME L.E-RAB.AbnormRel.MME counter is incremented according to the number of E-RAB releases

•

UE CONTEXT RELEASE COMMAND  As

in figure 2 all RABs for the UE/s UE/s are released each time the UE context release is ini initiated tiated by the MME and and the eNodeB eNodeB receives receives a UE CONTEXT RELEASE COMMAND message from the MME. The L.E-RAB.AbnormRel.MME counter is incremented each time the Release C Cause ause information element of the message is not Normal Release, Release, Detach Detach,, User Inactivity, Inactivity, or cs fallback fallback triggered triggered.. If the UE CONTEXT RELEASE COMMAND message requires multiple E-RAB releases at the same time, the L.E-RAB.AbnormRel.MME counter is incremented according to the number of E-RAB releases. HUAWEI TECHNOLOGIES CO., LTD.

Huawei Confidential

Page 6

 

E-RABAbno rmal Rel. Rel.Radio Radio/TNL/ /TNL/Cong Congestio estion n E-RABAbnormal As in Figure 3 The eNodeB sends an E-RAB RELEASE INDICA INDICATION TION message to the MME. MME. The L.E-RAB.AbnormRel.Radio L.E-RAB.AbnormRel.Radio counter is incremented each time the access layer layer bearer resources are abnormally released due to faults at the radio r adio network layer.





The L.E-RAB.AbnormRel.TNL counter is incremented each time the resources are abnormally abnormally released due to faults at the t he transport network layer.  The L.E-RAB.AbnormRel.Cong counter is incremented each time the resources are abnormally released due to network congestion including preemption and resource congestion. If the E-RAB RELEASE INDICATION INDICATION message requires multiple E-RAB rreleases eleases at the same time, the corresponding counter is incremented according to the number of required E-RAB releases. RELEASE COMMAND message back to the eNodeB, When the MME sends a UE CONTEXT RELEASE the corresponding counter is not incremented repeatedly •

Suspected reasons. Radio RF conditions TNL Transmission NE40 Congestion Users prioritizing Load(RAB bitrate is lower than a specific value) explained in details in the last slide. •

• •

•

•

HUAWEI TECHNOLOGIES CO., LTD.

Huawei Confidential

Page 7

HUAWEI TECHNOLOGIES CO., LTD.

Huawei Confidential

 

E-RA BAbn bnor orma mall Re Rel. l.HO HO fa fail ilur ure e E-RABA  As

in figure 4 the L.E-RAB.AbnormRel.HOFailure L.E-RAB.AbnormRel.HOFailure counter is incremented each time the resources are abnormally released due to handover failures. When the MME sends a UE CONTEXT RELEASE COMMAND COMMAND message back to the eNodeB, the corresponding counter is not incremented repeatedly. repeatedly. If the UE CONTEXT RELEASE REQUEST message requires multiple E-RAB releases at the same time, the corresponding counter is incremented according to the number of required E-RAB releases.

Page 8

HUAWEI TECHNOLOGIES CO., LTD.

Huawei Confidential

 

Examples from Nastar 

Page 9

HUAWEI TECHNOLOGIES CO., LTD.

Huawei Confidential

 

Radio/ Radio connection with UE lost

Page 9

HUAWEI TECHNOLOGIES CO., LTD.  

HO Failure

Huawei Confidential

Page 10

HUAWEI TECHNOLOGIES CO., LTD.

Huawei Confidential

 

No Radio resources available

Page 11

HUAWEI TECHNOLOGIES CO., LTD.

Huawei Confidential

Page 12

 

Queries •

Need to confirm how the E-NodB is recognizing between different causes ( Radio, TNL & congestion) from messages sent from the the E-NodB (found in Nastar). ( No Radio Resources available available ) sent from e-nodb e-nodb may indicate ERABAbnormal ERABAbnormal •

release.congestion ( Radio connection with UE lost ) sent from e-nodb may indicate ERABAbnormal ERABAbnormal release.Radio As per document below it may mean that RABs having low bit rate lower than a specific threshold will be released due to load so Is E-RABAbnormal E-RABAbnormal Rel.cong. counter is covering this case. What is the threshold value for minimum bit rate for each RAB •

•

•

•

HUAWEI TECHNOLOGIES CO., LTD.

Huawei Confidential

 

Thank You

HUAWEI TECHNOLOGIES CO., LTD.

Page 13