NR MRO中RLF report信息阅读

继续总结NR MRO中所使用的几个流程的进一步信息，本篇文章也可以算作2021精华文（17）MRO相关规范总结的续集，用于进一步聊聊MRO中可能使用的几条消息的详细内容。首先在2021精华文（17）MRO相关规范总结讲到RLF report的上报机制。UE使用在如下几条RRC消息中的IE rlf-InfoAvailable-r16来告知网络侧它已经获取到了相应的rlf信息，即为：

然后gNB收到UE的这个IE通知后，会通过如下这两个消息要求UE上报已经获取的rlf info，UE继而将之报告gNB：

从上面这对RRC消息来看，gNB在UEInformationRequest-r16中包含了请求UE上报rlf的信息rlf-ReportReq-r16，然后UE在使用UEinformationResponse回应时将rlf report上报给gNB。RLF Report里的信息非常丰富，在MRO中的判决流程的主要信息依据，尤其重要，我们将之详细展开，这里我们将重点关注NR rlf信息部分，重点的部分做了编号，如下所示：

1. 即 measResultLastServCell-r16

MeasResultRLFNR-r16,包含了NR服务小区的测量结果信息。这些信息包含了基于cell的测量结果和精细到cell内所使用的每个RS的测量结果，当然是可选的IE。

2和3. 第2和第3分别是针对NR邻区和EUTRAN邻区的测量结果，我们以NR邻区为例，主要也是上报的NR邻区及邻区内各个RS的测量结果，那个CGIinfo-NR主要用于相关ANR流程：

measResultListNR-r16                 MeasResultList2NR-r16

measResultListNR

This field refers to the last measurement results taken in the neighboring NR Cells, when the radio link failure or handover failure happened.

4.第四个是c-RNTI-r16，有关c-RNTI的规范文本如下，比较清晰：

This field indicates the C-RNTI used in the PCell upon detecting radio link failure or the C-RNTI used in the source PCell upon handover failure.

5.和6.用于指示之前切换中源cell所使用的两类PCI，

This field is used to indicate the source PCell of the last handover (source PCell when the last RRCReconfiguration message including reconfigurationWithSync was received). For intra-NR handover nrPreviousCell is included and for the handover from EUTRA to NR eutraPreviousCell is included.

7.和8.用于指示RLF发生所在的cell，包括了PCI（PCI+频点）和eCGI：

This field is used to indicate the PCell in which RLF is detected or the target PCell of the failed handover. For intra-NR handover nrFailedPCellId is included and for the handover from NR to EUTRA eutraFailedPCellIdis included. The UE sets the ARFCN according to thefrequency band used for transmission/ reception when the failure occurred.

9.和10.指示的是在经历了failure和重建失败后最终实际连接的cell。使用CGI+TAC。

This field is used to indicate the cell in which the UE comes back to connected after connection failure and after failing to perform reestablishment. If the UE comes back to RRC CONNECTED in an NR cell then nrReconnectCellID is included and if the UE comes back to RRC CONNECTED in an LTE cell then eutraReconnectCellID is included.

11. TimeUntilReconnection-r16::= INTEGER (0..172800)，记录UE从RLF到重新进入连接态的时段。

This field is used to indicate the time that elapsed between the connection (radio link or handover) failure and the next time the UE comes to RRC CONNECTED in an NR or EUTRA cell, after failing to perform reestablishment.Value in seconds. The maximum value 172800 means 172800s or longer.

12.reestablishmentCellId，规范中定义如下，也是使用使用CGI+TAC：This field is used to indicate the cell in which the re-establishment attempt was made after connection failure.

13.timeConnFailure-r16，用于记录从最近一次发起切换直到RLF发生的时段，规范中定义如下：

This field is used to indicate the time elapsed since the last HO initialization until connection failure. Actual value = field value * 100ms. The maximumvalue 1023 means 102.3s or longer.

14.timeSinceFailure-r16，用于记录从RLF发生迄今为止所经历的时间，规范文本如下：

This field is used to indicate the time that elapsed since the connection (radio link or handover failure）.Value in seconds. The maximum value 172800 means 172800s or longer.

15.connectionFailureType-r16，用于UE报告该failure是RLF还是切换失败。就是connection failure类型。

16.rlf-Cause-r16，顾名思义即为RLF的原因值，即此字段用于指示上次检测到的RLF的原因。在切换失败的情况下（即connectionFailureType设置为“hof”），允许UE将该字段设置为任何值。

17. locationInfo-r16，用于指示报告各类location的，如下：

LocationInfo-r16::=      SEQUENCE {

commonLocationInfo-r16    CommonLocationInfo-r16          OPTIONAL,

bt-LocationInfo-r16       LogMeasResultListBT-r16         OPTIONAL,

wlan-LocationInfo-r16     LogMeasResultListWLAN-r16       OPTIONAL,

sensor-LocationInfo-r16   Sensor-LocationInfo-r16         OPTIONAL,

...

}

18. noSuitableCellFound-r16，UE在T311超时的时候使用它，表明搜不到合适的cell驻留。

在前文2021精华文（17）MRO相关规范总结已经说了RLF report报告的流程已经在Xn，NG，F1接口上的传递过程和消息。请参考之，此处不再赘述。