8/11/2019 LTE ERAB AbNormal Release Causes Correct _1 E-RAB Abnormal Release Causes HUAWEI TECHNOLOGIES CO., LTD. http://slidepdf.com/reader/full/lte-erab-abnormal-release-causes-correct-1 HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential 1/14 8/11/2019 LTE ERAB AbNormal Release Causes Correct _1 Contents • Counters names & description • Abnormal Releases causes mapping • Difference between E-RAB Release & UE Context release Command messages • Types of Normal Releases. • Abnormal Releases causes Measurement points – – MME Radio – TNL – HO failure – Congestion • Examples from Nastar for some ERABAbnormal releases • Queries about ERABAbnormal Release due to load. http://slidepdf.com/reader/full/lte-erab-abnormal-release-causes-correct-1 HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential Page 2 2/14 Counters names & description and related KPI 8/11/2019 LTE ERAB AbNormal Release Causes Correct _1 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 http://slidepdf.com/reader/full/lte-erab-abnormal-release-causes-correct-1 HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential Page 3 3/14 Abnormal Releases causes mapping 8/11/2019 LTE ERAB AbNormal Release Causes Correct _1 UE MME/SGW E-RAB E-NodB E-RABAbnormal Rel.Cong.* E-RABAbnormal Rel.HOfail E-RABAbnormal Rel.Radio • E-RABAbnormal Rel.TNL E-RABAbnormal Rel.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 ) http://slidepdf.com/reader/full/lte-erab-abnormal-release-causes-correct-1 HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential Page 4 4/14 Difference between E-RAB Release & UE Context release 8/11/2019 • LTE ERAB AbNormal Release Causes Correct _1 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. Detach User Inactivity CS fallback triggered http://slidepdf.com/reader/full/lte-erab-abnormal-release-causes-correct-1 HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential Page 5 5/14 E-RABAbnormal 8/11/2019 • LTE ERAB AbNormaltriggering Release Causes Correct _1 Rel.MME’s two msgs. E-RAB RELEASE COMMAND As in figure 1 the L.E-RAB.AbnormRel.MME counter is incremented 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, Detach, User Inactivity, or cs fallback triggered. If the E-RAB 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 • UE CONTEXT RELEASE COMMAND As in figure 2 all RABs for the UE/s are released each time the UE context release is initiated by the MME and the eNodeB receives a UE CONTEXT RELEASE COMMAND message from the MME. The L.E-RAB.AbnormRel.MME counter is incremented each time the Release Cause information element of the message is not Normal Release, Detach, User Inactivity, or cs fallback 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. http://slidepdf.com/reader/full/lte-erab-abnormal-release-causes-correct-1 Huawei Confidential Page 6 6/14 E-RABAbnormal Rel.Radio/TNL/Congestion 8/11/2019 LTE ERAB AbNormal Release Causes Correct _1 As in Figure 3 The eNodeB sends an E-RAB RELEASE INDICATION message to the MME. The L.E-RAB.AbnormRel.Radio counter is incremented each time the access layer bearer resources are abnormally released due to faults at the radio network layer. The L.E-RAB.AbnormRel.TNL counter is incremented each time the resources are abnormally released due to faults at the 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 message requires multiple E-RAB releases at the same time, the corresponding counter is incremented according to the number of required E-RAB releases. When the MME sends a UE CONTEXT RELEASE COMMAND message back to the eNodeB, 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. http://slidepdf.com/reader/full/lte-erab-abnormal-release-causes-correct-1 Huawei Confidential Page 7 7/14 E-RABAbnormal Rel.HO failure 8/11/2019 LTE ERAB AbNormal Release Causes Correct _1 As in figure 4 the 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 message back to the eNodeB, the corresponding counter is not incremented 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. HUAWEI TECHNOLOGIES CO., LTD. http://slidepdf.com/reader/full/lte-erab-abnormal-release-causes-correct-1 Huawei Confidential Page 8 8/14 8/11/2019 LTE ERAB AbNormal Release Causes Correct _1 Examples from Nastar HUAWEI TECHNOLOGIES CO., LTD. http://slidepdf.com/reader/full/lte-erab-abnormal-release-causes-correct-1 Huawei Confidential Page 9 9/14 Radio/ Radio connection with UE lost 8/11/2019 HUAWEI TECHNOLOGIES CO., LTD. http://slidepdf.com/reader/full/lte-erab-abnormal-release-causes-correct-1 LTE ERAB AbNormal Release Causes Correct _1 Huawei Confidential Page 10 10/14 HO Failure 8/11/2019 HUAWEI TECHNOLOGIES CO., LTD. http://slidepdf.com/reader/full/lte-erab-abnormal-release-causes-correct-1 LTE ERAB AbNormal Release Causes Correct _1 Huawei Confidential Page 11 11/14 No Radio resources available 8/11/2019 LTE ERAB AbNormal Release Causes Correct _1 HUAWEI TECHNOLOGIES CO., LTD. http://slidepdf.com/reader/full/lte-erab-abnormal-release-causes-correct-1 Huawei Confidential Page 12 12/14 Queries 8/11/2019 • LTE ERAB AbNormal Release Causes Correct _1 Need to confirm how the E-NodB is recognizing between different causes ( Radio, TNL & congestion) from messages sent from the E-NodB (found in Nastar). ( No Radio Resources available ) sent from e-nodb may indicate ERABAbnormal release.congestion • ( Radio connection with UE lost ) sent from e-nodb may indicate 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 Rel.cong. counter is covering this case. What is the threshold value for minimum bit rate for each RAB • • • • HUAWEI TECHNOLOGIES CO., LTD. http://slidepdf.com/reader/full/lte-erab-abnormal-release-causes-correct-1 Huawei Confidential Page 13 13/14 8/11/2019 LTE ERAB AbNormal Release Causes Correct _1 Thank You HUAWEI TECHNOLOGIES CO., LTD. HUAWEI TECHNOLOGIES CO., LTD. http://slidepdf.com/reader/full/lte-erab-abnormal-release-causes-correct-1 Huawei Confidential 14/14
