LTE系统事件概况

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LTE系统事件概况

一、LTE事件概述

LTE切换时需要UE上报测量的结果（包括RSRP，RSRQ等），而上报又分为周期性上报和事件触发的上报。

Ø  周期性上报由基站配置，UE直接上报测量的结果。

Ø  事件触发的上报又分为系统内的事件和系统间的事件。

LTE系统内切换主要事件包括：

Ø  A1事件，服务小区质量高于门限；这个事件可以用来关闭频间测量。

Ø  A2事件，服务小区质量低于门限；这个事件可以用来打开频间测量和系统间测量，因为这个事件发生后可能发生切换等操作。

Ø  A3事件，邻小区质量好于服务小区质量；这个事件一般用于频内/间基于覆盖的切换。

Ø  A4事件，邻小区质量好于门限；这个事件一般用于基于负荷的切换。

Ø  A5事件，服务小区质量低于一个门限并且邻小区质量高于一个门限；这个事件也可以用于频内/间基于覆盖的切换。

目前LTE同频切换都是基于A3/A5事件进行的切换（现网主要是基于A3事件的）

二、切换流程举例

                                 

三、切换流程简要说明

-            RRC Connection Reconfiguration（Measurement Control）

测量控制，一般在初始接入或上一次切换命令中的重配消息里携带

-                Measurement Report

测量报告，终端根据当前小区的测量控制信息，将符合切换门限的小区进行上报

-                HO Request

源小区在收到测量报告后向目标小区申请资源及配置信息（站内切换的话为站内交互，站间切换会使用X2口或者S1口，优先使用X2口）

-                HO Request Ack

目标小区将终端的接纳信息以及其它配置信息反馈给源小区

-                RRCConnection Reconfiguration（HO Command）

将目标小区的接纳信息及配置信息发给终端，告知终端目标小区已准备好终端接入，重配消息里包含目标小区的测量控制

-                SN Status Transfer

源小区将终端业务的缓存数据移至目标小区

-                Random Access Preamble

终端收到第5步重配消息（切换命令）后使用重配消息里的接入信息进行接入

-                Random Access Response

目标小区接入响应，收到此命令后可认为接入完成了，然后终端在RRC层上发重配完成消息（第9步）

-                RRC Connect Reconfiguration complete（HO Confirm）

上报重配完成消息，切换完成

-                Release Resource

当终端成功接入后，目标小区通知源小区删除终端的上下文信息

四、协议对LTE事件的定义和说明 4.1  A1事件定义

Event A1 (Serving becomes better than threshold)

The UE shall:

1>  considerthe entering condition for this event to be satisfied when condition A1-1, asspecified below, is fulfilled;

1>  considerthe leaving condition for this event to be satisfied when condition A1-2, asspecified below, is fulfilled;

1>  forthis measurement, consider the primary or secondary cell that is configured onthe frequency indicated in the associated measObjectEUTRAto be the serving cell;

Inequality A1-1 (Entering condition)

Inequality A1-2 (Leaving condition)

The variables in the formula are defined asfollows:

Ms is the measurement result of the serving cell, not taking intoaccount any offsets.

Hys is the hysteresisparameter for this event (i.e. hysteresisas defined within reportConfigEUTRA for this event).

Thresh is thethreshold parameter for this event (i.e. a1-Thresholdas defined within reportConfigEUTRA for this event).

Ms is expressed in dBmin case of RSRP, or indB in case of RSRQ.

Hys is expressed indB.

Thresh is expressed in the same unit as Ms.

4.2  A2事件定义

Event A2 (Serving becomesworse than threshold)

The UE shall:

1>  considerthe entering condition for this event to be satisfied when condition A2-1, asspecified below, is fulfilled;

1>  considerthe leaving condition for this event to be satisfied when condition A2-2, asspecified below, is fulfilled;

1>  forthis measurement, consider the primary or secondary cell that is configured onthe frequency indicated in the associated measObjectEUTRAto be the serving cell;

Inequality A2-1 (Entering condition)

Inequality A2-2 (Leaving condition)

The variables in the formula are defined asfollows:

Ms is the measurement result of the serving cell, not taking intoaccount any offsets.

Hys is the hysteresisparameter for this event (i.e. hysteresisas defined within reportConfigEUTRA for this event).

Thresh is the thresholdparameter for this event (i.e. a2-Thresholdas defined within reportConfigEUTRA for this event).

Ms is expressed in dBm in case of RSRP, or in dB in caseof RSRQ.

Hys is expressed indB.

Thresh is expressed in the same unit as Ms.

4.3  A3事件定义

Event A3 (Neighbour becomesoffset better than PCell)

The UE shall:

1>  considerthe entering condition for this event to be satisfied when condition A3-1, asspecified below, is fulfilled;

1>  considerthe leaving condition for this event to be satisfied when condition A3-2, asspecified below, is fulfilled;

NOTE        The cell(s) that triggers the event ison the frequency indicated in the associated measObject which may be different from the (primary) frequency usedby the PCell.

Inequality A3-1 (Entering condition)

Inequality A3-2 (Leaving condition)

The variables in the formula are defined asfollows:

Mn is the measurement result of the neighbouring cell, not taking intoaccount any offsets.

Ofn is the frequencyspecific offset of the frequency of the neighbour cell (i.e. offsetFreq as defined within measObjectEUTRA corresponding to thefrequency of the neighbour cell).

Ocn is the cellspecific offset of the neighbour cell (i.e. cellIndividualOffsetas defined within measObjectEUTRAcorresponding to the frequency of the neighbour cell), and set to zero if notconfigured for the neighbour cell.

Mp is the measurement result of the PCell, not taking into account anyoffsets.

Ofp is the frequencyspecific offset of the primary frequency (i.e. offsetFreq as defined within measObjectEUTRAcorresponding to the primary frequency).

Ocp is the cellspecific offset of the PCell (i.e. cellIndividualOffsetas defined within measObjectEUTRA corresponding to the primary frequency), and isset to zero if not configured for the PCell.

Hys is the hysteresisparameter for this event (i.e. hysteresisas defined within reportConfigEUTRA for this event).

Off is the offsetparameter for this event (i.e. a3-Offset asdefined within reportConfigEUTRA for this event).

Mn, Mp are expressedin dBm in case of RSRP,or in dB in case of RSRQ.

Ofn, Ocn, Ofp, Ocp, Hys, Off are expressed in dB.

4.4  A4事件定义

Event A4 (Neighbour becomesbetter than threshold)

The UE shall:

1>  considerthe entering condition for this event to be satisfied when condition A4-1, asspecified below, is fulfilled;

1>  considerthe leaving condition for this event to be satisfied when condition A4-2, asspecified below, is fulfilled;

Inequality A4-1 (Entering condition)

Inequality A4-2 (Leaving condition)

The variables in the formula are defined asfollows:

Mn is the measurement result of the neighbouring cell, not taking intoaccount any offsets.

Ofn is the frequencyspecific offset of the frequency of the neighbour cell (i.e. offsetFreq as defined within measObjectEUTRA corresponding to thefrequency of the neighbour cell).

Ocn is the cellspecific offset of the neighbour cell (i.e. cellIndividualOffsetas defined within measObjectEUTRAcorresponding to the frequency of the neighbour cell), and set to zero if notconfigured for the neighbour cell.

Hys is the hysteresisparameter for this event (i.e. hysteresisas defined within reportConfigEUTRA for this event).

Thresh is thethreshold parameter for this event (i.e. a4-Thresholdas defined within reportConfigEUTRA for this event).

Mn is expressed in dBm in case of RSRP, or in dB in caseof RSRQ.

Ofn, Ocn, Hys areexpressed in dB.

Thresh is expressed in the same unit as Mn.

4.5  A5事件定义

Event A5 (PCell becomes worsethan threshold1 and neighbour becomes better than threshold2)

The UE shall:

1>  considerthe entering condition for this event to be satisfied when both condition A5-1and condition A5-2, as specified below, are fulfilled;

1>  considerthe leaving condition for this event to be satisfied when condition A5-3 orcondition A5-4, i.e. at least one of the two, as specified below, is fulfilled;

NOTE:      The cell(s) that triggersthe event is on the frequency indicated in the associated measObject which may be different from the (primary) frequency usedby the PCell.

Inequality A5-1 (Entering condition 1)

Inequality A5-2 (Entering condition 2)

Inequality A5-3 (Leaving condition 1)

Inequality A5-4 (Leaving condition 2)

The variables in the formula are defined asfollows:

Mp is the measurement result of the PCell, not taking into account anyoffsets.

Mn is the measurement result of the neighbouring cell, not taking intoaccount any offsets.

Ofn is the frequencyspecific offset of the frequency of the neighbour cell (i.e. offsetFreq as defined within measObjectEUTRA corresponding to thefrequency of the neighbour cell).

Ocn is the cellspecific offset of the neighbour cell (i.e. cellIndividualOffsetas defined within measObjectEUTRAcorresponding to the frequency of the neighbour cell), and set to zero if notconfigured for the neighbour cell.

Hys is the hysteresisparameter for this event (i.e. hysteresisas defined within reportConfigEUTRA for this event).

Thresh1 is thethreshold parameter for this event (i.e. a5-Threshold1as defined within reportConfigEUTRA for this event).

Thresh2 is the thresholdparameter for this event (i.e. a5-Threshold2as defined within reportConfigEUTRA for this event).

Mn, Mp are expressedin dBm in case of RSRP,or in dB in case of RSRQ.

Ofn, Ocn, Hys areexpressed in dB.

Thresh1 is expressedin the same unit as Mp.

Thresh2 is expressedin the same unit as Mn.

4.6  A6事件定义

Event A6 (Neighbour becomesoffset better than SCell)

The UE shall:

1>  considerthe entering condition for this event to be satisfied when condition A6-1, asspecified below, is fulfilled;

1>  considerthe leaving condition for this event to be satisfied when condition A6-2, asspecified below, is fulfilled;

1>  forthis measurement, consider the (secondary) cell that is configured on thefrequency indicated in the associated measObjectEUTRAto be the serving cell;

NOTE:      The neighbour(s) is on the same frequencyas the SCell i.e. both are on the frequency indicated in the associated measObject.

Inequality A6-1 (Entering condition)

Inequality A6-2 (Leaving condition)

The variables in the formula are defined asfollows:

Mn is the measurement result of the neighbouring cell, not taking intoaccount any offsets.

Ocn is the cellspecific offset of the neighbour cell (i.e. cellIndividualOffsetas defined within measObjectEUTRAcorresponding to the frequency of the neighbour cell), and set to zero if notconfigured for the neighbour cell.

Ms is the measurement result of the serving cell, not taking intoaccount any offsets.

Ocs is the cellspecific offset of the serving cell (i.e. cellIndividualOffsetas defined within measObjectEUTRA corresponding to the serving frequency), and isset to zero if not configured for the serving cell.

Hys is the hysteresisparameter for this event (i.e. hysteresisas defined within reportConfigEUTRA for this event).

Off is the offsetparameter for this event (i.e. a6-Offset asdefined within reportConfigEUTRA for this event).

Mn, Ms are expressedin dBm in case of RSRP,or in dB in case of RSRQ.

Ocn, Ocs, Hys, Off areexpressed in dB.

4.7  B1事件定义

Event B1 (Inter RAT neighbourbecomes better than threshold)

The UE shall:

1>  forUTRA and CDMA2000, only trigger the event for cells included in thecorresponding measurement object;

1>  considerthe entering condition for this event to be satisfied when condition B1-1, asspecified below, is fulfilled;

1>  considerthe leaving condition for this event to be satisfied when condition B1-2, asspecified below, is fulfilled;

Inequality B1-1 (Entering condition)

Inequality B1-2 (Leaving condition)

The variables in the formula are defined asfollows:

Mn is the measurement result of the inter-RAT neighbour cell, nottaking into account any offsets. For CDMA 2000 measurement result, pilotStrength is divided by -2.

Ofn is the frequencyspecific offset of the frequency of the inter-RAT neighbour cell (i.e. offsetFreq as defined within the measObject corresponding to thefrequency of the neighbour inter-RAT cell).

Hys is the hysteresisparameter for this event (i.e. hysteresisas defined within reportConfigInterRAT for this event).

Thresh is thethreshold parameter for this event (i.e. b1-Thresholdas defined withinreportConfigInterRAT for this event).For CDMA2000, b1-Threshold is dividedby -2.

Mn is expressed in dBmor in dB, depending onthe measurement quantity of the inter-RAT neighbour cell.

Ofn, Hys are expressedin dB.

Thresh is expressed in the same unit as Mn.

4.8  B2事件定义

Event B2 (PCell becomes worsethan threshold1 and inter RAT neighbour becomes better than threshold2)

The UE shall:

1>  forUTRA and CDMA2000, only trigger the event for cells included in thecorresponding measurement object;

1>  considerthe entering condition for this event to be satisfied when both condition B2-1and condition B2-2, as specified below, are fulfilled;

1>  considerthe leaving condition for this event to be satisfied when condition B2-3 orcondition B2-4, i.e. at least one of the two, as specified below, is fulfilled;

Inequality B2-1 (Entering condition 1)

Inequality B2-2 (Entering condition 2)

Inequality B2-3 (Leaving condition 1)

Inequality B2-4 (Leaving condition 2)

The variables in the formula are defined asfollows:

Mp is the measurement result of the PCell, not taking into account anyoffsets.

Mn is the measurement result of the inter-RAT neighbour cell, nottaking into account any offsets. For CDMA2000 measurement result, pilotStrength is divided by -2.

Ofn is the frequencyspecific offset of the frequency of the inter-RAT neighbour cell (i.e. offsetFreq as defined within the measObject corresponding to thefrequency of the inter-RAT neighbour cell).

Hys is the hysteresisparameter for this event (i.e. hysteresisas defined within reportConfigInterRAT for this event).

Thresh1 is thethreshold parameter for this event (i.e. b2-Threshold1as defined withinreportConfigInterRAT for this event).

Thresh2 is thethreshold parameter for this event (i.e. b2-Threshold2as defined withinreportConfigInterRAT for this event).For CDMA2000, b2-Threshold2 is dividedby -2.

Mp is expressed in dBmin case of RSRP, or indB in case of RSRQ.

Mnis expressed in dBm or dB, depending on the measurement quantity of theinter-RAT neighbour cell.

Ofn, Hys are expressedin dB.

Thresh1 is expressedin the same unit as Mp.

Thresh2 is expressedin the same unit as Mn.