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NR测量事件
无线通信系统的移动性管理,均是通过 UE上报的测量报告,基站来判断是否满
足切换条件,而测量报告一般可以根据覆盖( RSRP)、质量( RSRQ、SINR)来进
行上报,上报的形式有周期性和基于事件触发, 周期性主要是上报最强的覆盖校
区,也就是网络采集覆盖情况,事件触发一般是切换(也可能是重定向等) 。
理想情况下,基站应允许 UE报告服务小区和相邻小区的信号质量,并通过单次
测量触发切换,但在实际应用中,由于不必要的乒乓切换,会造成过载情况。为
了避免这种情况, 3GPP规范提出了一套由 UE执行的预定义的测量报告机制。这
些预定义的度量报告类型称为“事件( EVENT)”。UE必须报告的“事件”的类型
由基站发送的 RRC信令消息指定。
3GPP 规范 38.331 为 NR定义了如下事件:
Event A1 (Serving becomes better than threshold)
Event A2 (Serving becomes worse than threshold)
Event A3 (Neighbor becomes offset better than SpCell)
Event A4 (Neighbor becomes better than threshold)
Event A5 (SpCell becomes worse than threshold1 and neighbor becomes
better than threshold2)
Event A6 (Neighbour becomes offset better than SCell)
Event B1 (Inter RAT neighbour becomes better than threshold)
Event B2 (PCell becomes worse than threshold1 and inter RAT neighbor
becomes better than threshold2)
和 LTE一样,可以将上面这些事件分为 A1-A6 和 B1-B2两类,一般 A类事件用于
系统内, B事件用于系统间。下表针对不同的事件总结了一些参数和范围
Event Parameter Range Value
A1, A2, A4, A5, B1 RSRP threshold 0 127 -156
dBm
-31 dBm
RSRQ threshold 0 127 -40 dB 20dB
SINR threshold 0 127 -23
dB
40 dB
All Hysteresis 0 30 0 dB 15 dB
A3, A6 Offset -
30
30 -15 dB +15 dB
A3,A4,A5,A6,B1,B2 Cell Specific
Offset
-24
dB
+24 dB