某4G区域终端有时驻留弱信号小区分析

出现问题时都是band1 100频点下发了针对弱信号的1650频点的连接态A4测量事件配置（其阈值为-106）。而这个条件很容易满足，一旦下发就会切到band3 1650频点。

而1650频点虽然下发band1 100的测量参数，但是又一直不理终端发给网络的band1 100的测量报告。只有终端从band3 1650切到band3 1850后，在band3 1850上才可以切回到信号好的band1 100.

1850频点在电梯旁的大厅信号强，很多其他位置1650 1850频点都比较弱，所以这些地点一旦连接态切到1650频点上比较难上报1850频点的测量报告。导致某段时间一直在弱信号band3 1650频点上。

小区情况

PCI 212小区在band1 100频点上。PCi 12,13，14在band3 1650频点上。PCI 361 是1850频点

先简单总结日志现象：

12:12:38.307003 网络下发针对1650的A4测量配置（-106db即可满足），终端从band1 100（-93db），上报band3 1650的A4测量报告，切到弱信号band3 1650（-104db）。

切到1650后，基站下发的功率检测参数包含了band1的100频点。所以终端可以检测100频点的信号的。

终端一直在上报100频点pci 212的测量报告（-98到-95db），但是网络一直不下发重配置消息。所以终端只能待在band3 1650.

直到终端12:14:13.844002上报band 3 1850 pci 361小区的功率检测上报,终端才进入band3 1850频点（-102db）。当然这个频点在当前位置也比较弱。

最终 12:14:15.598006 在1850频点上上报band1 100 ，pci212 小区（-102db），才成功切回band1.

所以针对这份日志，band1某些时候对band3 1650 弱信号频点下发很容易满足的A4测量，切到1650弱信号频点。而1650小区基站不处理band1的测量报告。只有切到同样弱的1850小区。1850基站对band1的测量报告正常进行处理，才可以切回band1。

连接态测量上报事件定义

EventA1-服务小区质量高于一个绝对门限（serving>threshold）。用于关闭正在进行的频间测量，在RRC控制下去掉激活测量间隙(gap).

EventA2-服务小区质量低于一个绝对门限（serving<threshold）。用于打开频间测量，在RRC控制下激活测量间隙(gap).

EventA3-邻小区比服务小区质量高于一个门限（Neighbour>serving+Offset）。用于频内/频间的基于覆盖的切换。

EventA4-邻小区质量高于一个绝对门限。用于基于负荷的切换。可用于负载平衡，与移动到高优先级的小区重选相似。

EventA5-服务小区质量低于一个绝对门限门限1（serving<threshold1）并且邻小区质量高于一个绝对门限2（serving>threshold2）。用于频内/频间的基于覆盖的切换。可用于负载平衡，与移动到低优先级的小区重选相似。

连接态切换的流程

1. 首先网络在RRCConfiguration/RRCReConfiguration消息中下发measIdToAddModList，告诉终端A1-A5的测量配置，需要测量哪些band 和频点，触发的阈值是什么。
2. 终端根据网络下发的配置，发现满足阈值后，就上报对应事件的MeasurementReport消息。
3. 然后网络收到终端的测量报告后，通过下发包含targetPhysCellId以及详细切换参数的RRCReConfiguration消息指示终端切换

终端不能主动切换，只能发送测量报告，等待网络通知切换。因为网络侧需要通知目标小区，目标小区获取终端在网络侧的各种上下文信息，准备好后资源，终端才可以切换成功。

12:12:38.307003 网络下发针对1650的A4测量配置，终端从band1 100，上报band3 1650的A4测量报告，切到band3 1650

之前比较稳定在band1上，是因为网络没有下发针对band3 1650的A4事件测量。12:12:37.529003 终端下发了针对band3 1650和1506的A4测量配置。而且这个配置比较容易满足。rsrp为-106db即满足条件。

所以终端在12:12.38.244250上报了band3 1650 pci 14的A4事件，当时band3 1650上的PCI 14的小区rsrp为-104db， band1 100的当前小区为-93db。虽然当前小区信号好，但是band3 1650的信号满足了比-106db大。所以上报了测量报告。

RSRP= -140+RsrpResult(dBm)

1. 12:12:37.529003 [0xB0C0] ELS_DL_DCCH / ELS RRCConnectionReconfiguration
2. Radio Bearer ID = 1, Physical Cell ID = 212
3. Freq = 100
4. PDU Number = ELS_DL_DCCH Message,    Msg Length = 33
5. Interpreted PDU:
7. value ELS-DL-DCCH-Message ::= 
8. {
9.   message c1 : els-RRCConnectionReconfiguration : 
10.       {
11.           CONTAINING
12.           {
13.             rrc-TransactionIdentifier 2,
14.             criticalExtensions c1 : rrcConnectionReconfiguration-r8 : 
15.                 {
16.                   measConfig 
17.                   {
18.                     measObjectToAddModList 
19.                     {
20.                       {
21.                         measObjectId 2,
22.                         measObject measObjectEUTRA : 
23.                           {
24.                             carrierFreq 1650,
25.                             allowedMeasBandwidth mbw100,
26.                             presenceAntennaPort1 FALSE,
27.                             neighCellConfig '01'B
28.                           }
29.                       },//添加了测量对象为1650频点
30.                       {
31.                         measObjectId 3,
32.                         measObject measObjectEUTRA : 
33.                           {
34.                             carrierFreq 1506,
35.                             allowedMeasBandwidth mbw50,
36.                             presenceAntennaPort1 FALSE,
37.                             neighCellConfig '01'B
38.                           }
39.                       }
40.                     },
41.                     reportConfigToAddModList 
42.                     {
43.                       {
44.                         reportConfigId 3,
45.                         reportConfig reportConfigEUTRA : 
46.                           {
47.                             triggerType event : 
48.                               {
49.                                 eventId eventA4 : 
50.                                   {
51.                                     a4-Threshold threshold-RSRP : 34//rsrp为-106db即满足条件。这个配置要求的信号比较低，非常容易满足。
52.                                   },
53.                                 hysteresis 0,
54.                                 timeToTrigger ms320 //满足上述阈值320ms即可以触发测量报告
55.                               },
56.                             triggerQuantity rsrp,
57.                             reportQuantity sameAsTriggerQuantity,
58.                             maxReportCells 3,
59.                             reportInterval ms1024,
60.                             reportAmount r1,
61.                             includeLocationInfo-r10 true
62.                           }
63.                       }
64.                     },
65.                     measIdToAddModList 
66.                     {
67.                       {
68.                         measId 3,//后面终端就上报了measid3 的测量报告。
69.                         measObjectId 2,//参见上面的measObjectId 2，指定了1650频点
70.                         reportConfigId 3//参见上面的reportConfigId 3，指定了A4事件。所以measID3 指定了针对1650频点的A4测量配置。
71.                       },
72.                       {
73.                         measId 4,
74.                         measObjectId 3,
75.                         reportConfigId 3
76.                       }
77.                     },
78.                     measGapConfig setup : 
79.                       {
80.                         gapOffset gp1 : 2
81.                       },
82.                     s-Measure 90
83.                   }
84.                 }
85.           },

终端上报band3 1650，pci14的小区测量报告。

1. 12:12:38.244250 [0xB0C0] UL_DCCH / MeasurementReport
2. Pkt Version = 22
3. RRC Release Number.Major.minor = 12.7.6
4. Radio Bearer ID = 1, Physical Cell ID = 212
5. Freq = 100
6. criticalExtensions c1 : measurementReport-r8 : 
7. {
8. measResults 
9. {
10. measId 3,//参见上面measID3的配置
11. measResultPCell 
12. {
13. rsrpResult 47,//PCell即primarycell为当前小区，rsrp为47-140= -93dbm
14. rsrqResult 14
15. },
16. measResultNeighCells measResultListEUTRA : 
17. {
18. {
19. physCellId 14,
20. measResult 
21. {
22. rsrpResult 36//pci为14的小区，rsrp为36-140=-104. 比当前小区低
23. }
24. }

网络收到A4测量报告，回复了RRC重配，通知终端切到band3 1650。

切到1650后，基站下发的功率检测参数包含了band1的100频点。所以终端可以检测100频点的信号的。

针对band3 1850和band1 100都下发了A5事件检测，当前小区低于-105，邻小区高于-103即可以触发测量报告。由于1650频点比较弱，这个测量报告其实很容易触发。

1. 12:12:38.766112 [0xB0C0] ELS_DL_DCCH / ELS RRCConnectionReconfiguration
2. Pkt Version = 22
3. RRC Release Number.Major.minor = 12.7.6
4. Radio Bearer ID = 1, Physical Cell ID = 14
5. Freq = 1650
6. SysFrameNum = 718, SubFrameNum = 1
7. PDU Number = ELS_DL_DCCH Message,    Msg Length = 83
8. SIB Mask in SI =  0x00
10. Interpreted PDU:
12. value ELS-DL-DCCH-Message ::= 
13. {
14.   message c1 : els-RRCConnectionReconfiguration : 
15.       {
16.         rrc-TransactionIdentifier 1,
17.         rRCConnectionReconfiguration 
18.           CONTAINING
19.           {
20.             rrc-TransactionIdentifier 1,
21.             criticalExtensions c1 : rrcConnectionReconfiguration-r8 : 
22.                 {
23.                   measConfig 
24.                   {
25.                     measObjectToAddModList 
26.                     {
27.                       {
28.                         measObjectId 2,
29.                         measObject measObjectEUTRA : 
30.                           {
31.                             carrierFreq 1850,
32.                             allowedMeasBandwidth mbw100,
33.                             presenceAntennaPort1 FALSE,
34.                             neighCellConfig '01'B
35.                           }
36.                       },
37.                       {
38.                         measObjectId 3,
39.                         measObject measObjectEUTRA : 
40.                           {
41.                             carrierFreq 450,
42.                             allowedMeasBandwidth mbw6,
43.                             presenceAntennaPort1 FALSE,
44.                             neighCellConfig '01'B
45.                           }
46.                       },
47.                       {
48.                         measObjectId 4,
49.                         measObject measObjectEUTRA : 
50.                           {
51.                             carrierFreq 1506,
52.                             allowedMeasBandwidth mbw50,
53.                             presenceAntennaPort1 FALSE,
54.                             neighCellConfig '01'B
55.                           }
56.                       },
57.                       {
58.                         measObjectId 5,
59.                         measObject measObjectEUTRA : 
60.                           {
61.                             carrierFreq 3740,
62.                             allowedMeasBandwidth mbw6,
63.                             presenceAntennaPort1 FALSE,
64.                             neighCellConfig '01'B,
65.                             offsetFreq dB-8
66.                           }
67.                       },
68.                       {
69.                         measObjectId 6,
70.                         measObject measObjectEUTRA : 
71.                           {
72.                             carrierFreq 100,
73.                             allowedMeasBandwidth mbw100,
74.                             presenceAntennaPort1 FALSE,
75.                             neighCellConfig '01'B
76.                           }
77.                       },
78.                       {
79.                         measObjectId 7,
80.                         measObject measObjectEUTRA : 
81.                           {
82.                             carrierFreq 300,
83.                             allowedMeasBandwidth mbw6,
84.                             presenceAntennaPort1 FALSE,
85.                             neighCellConfig '01'B
86.                           }
87.                       }
88.                     },
89.                     reportConfigToRemoveList 
90.                     {
91.                       2
92.                     },
93.                     reportConfigToAddModList 
94.                     {
95.                       {
96.                         reportConfigId 2,
97.                         reportConfig reportConfigEUTRA : 
98.                           {
99.                             triggerType event : 
100.                               {
101.                                 eventId eventA5 : 
102.                                   {
103.                                     a5-Threshold1 threshold-RSRP : 35,//当前小区低于-105db
104.                                     a5-Threshold2 threshold-RSRP : 37//邻小区高于-103db。
105.                                   },
106.                                 hysteresis 0,
107.                                 timeToTrigger ms320
108.                               },
109.                             triggerQuantity rsrp,
110.                             reportQuantity both,
111.                             maxReportCells 3,
112.                             reportInterval ms1024,
113.                             reportAmount r1,
114.                             includeLocationInfo-r10 true
115.                           }
116.                       },
117.                       {
118.                         reportConfigId 4,
119.                         reportConfig reportConfigEUTRA : 
120.                           {
121.                             triggerType event : 
122.                               {
123.                                 eventId eventA5 : 
124.                                   {
125.                                     a5-Threshold1 threshold-RSRP : 35,
126.                                     a5-Threshold2 threshold-RSRP : 37
127.                                   },
128.                                 hysteresis 0,
129.                                 timeToTrigger ms320
130.                               },
131.                             triggerQuantity rsrp,
132.                             reportQuantity both,
133.                             maxReportCells 3,
134.                             reportInterval ms1024,
135.                             reportAmount r1,
136.                             includeLocationInfo-r10 true
137.                           }
138.                       },
139.                       {
140.                         reportConfigId 5,
141.                         reportConfig reportConfigEUTRA : 
142.                           {
143.                             triggerType event : 
144.                               {
145.                                 eventId eventA1 : 
146.                                   {
147.                                     a1-Threshold threshold-RSRP : 45
148.                                   },
149.                                 hysteresis 0,
150.                                 timeToTrigger ms320
151.                               },
152.                             triggerQuantity rsrp,
153.                             reportQuantity both,
154.                             maxReportCells 1,
155.                             reportInterval ms1024,
156.                             reportAmount r1,
157.                             includeLocationInfo-r10 true
158.                           }
159.                       }
160.                     },
161.                     measIdToAddModList 
162.                     {
163.                       {
164.                         measId 2,
165.                         measObjectId 2,//参见上面measObjectId 2，指定了1850频点测量对象
166.                         reportConfigId 2// reportConfigId 2，指定了A5测量参数
167.                       },
168.                       {
169.                         measId 4,
170.                         measObjectId 3,
171.                         reportConfigId 4
172.                       },
173.                       {
174.                         measId 5,
175.                         measObjectId 4,
176.                         reportConfigId 4
177.                       },
178.                       {
179.                         measId 6,
180.                         measObjectId 5,
181.                         reportConfigId 4
182.                       },
183.                       {
184.                         measId 7,
185.                         measObjectId 6,//参见上面measObjectId 6，指定了100频点测量对象
186.                         reportConfigId 2// reportConfigId 2，指定了A5测量参数
187.                       },
188.                       {
189.                         measId 8,
190.                         measObjectId 7,
191.                         reportConfigId 4
192.                       },
193.                       {
194.                         measId 9,
195.                         measObjectId 1,
196.                         reportConfigId 5
197.                       }
198.                     },
199.                     measGapConfig setup : 
200.                       {
201.                         gapOffset gp1 : 1
202.                       },
203.                     s-Measure 90
204.                   }
205.                 }
206.           },
207.         criticalExtensions c1 : els-rrcConnectionReconfiguration-r1 : 
208.             {
209.             }
210.       }
211. }

终端一直在上报100频点pci 212的测量报告，但是网络一直不下发重配置消息。所以终端只能待在band3 1650

终端上报的band100的信号为-95，当前小区为-107db。但是网络就是不通知终端切换。

1. 12:12:41.204261 [0xB0C0] UL_DCCH / MeasurementReport
2. Pkt Version = 22
3. RRC Release Number.Major.minor = 12.7.6
4. Radio Bearer ID = 1, Physical Cell ID = 14
5. Freq = 1650
6. SysFrameNum = N/A, SubFrameNum = 0
7. PDU Number = UL_DCCH Message,    Msg Length = 26
8. SIB Mask in SI =  0x00
10. Interpreted PDU:
12. value UL-DCCH-Message ::= 
13. {
14.   message c1 : measurementReport : 
15.       {
16.         criticalExtensions c1 : measurementReport-r8 : 
17.             {
18.               measResults 
19.               {
20.                 measId 7,
21.                 measResultPCell 
22.                 {
23.                   rsrpResult 33,//当前信号-107db
24.                   rsrqResult 10
25.                 },
26.                 measResultNeighCells measResultListEUTRA : 
27.                   {
28.                     {
29.                       physCellId 212,
30.                       measResult 
31.                       {
32.                         rsrpResult 45,//band1 pci 212 小区的信号是-95db
33.                         rsrqResult 9
34.                       }
35.                     }
36.                   },
37.                 locationInfo-r10 
38.                 {
39.                   locationCoordinates-r10 ellipsoidPointWithAltitude-r10 : '201498D105C90035'H,
40.                   gnss-TOD-msec-r10 '2F7784'H
41.                 }
42.               }
43.             }
44.       }
45. }

直到终端12:14:13.844002上报band 3 1850 pci 361小区的功率检测上报,终端才进入band3 1850频点

1. 12:14:13.844002 [0xB0C0] UL_DCCH / MeasurementReport
2. Pkt Version = 22
3. RRC Release Number.Major.minor = 12.7.6
4. Radio Bearer ID = 1, Physical Cell ID = 14
5. Freq = 1650
6. SysFrameNum = N/A, SubFrameNum = 0
7. PDU Number = UL_DCCH Message,    Msg Length = 26
8. SIB Mask in SI =  0x00
10. Interpreted PDU:
12. value UL-DCCH-Message ::= 
13. {
14.   message c1 : measurementReport : 
15.       {
16.         criticalExtensions c1 : measurementReport-r8 : 
17.             {
18.               measResults 
19.               {
20.                 measId 2,
21.                 measResultPCell 
22.                 {
23.                   rsrpResult 31,
24.                   rsrqResult 12
25.                 },
26.                 measResultNeighCells measResultListEUTRA : 
27.                   {
28.                     {
29.                       physCellId 361,
30.                       measResult 
31.                       {
32.                         rsrpResult 38,//-102db
33.                         rsrqResult 26
34.                       }
35.                     }
36.                   },
37.                 locationInfo-r10 
38.                 {
39.                   locationCoordinates-r10 ellipsoidPointWithAltitude-r10 : '201499D105C90036'H,
40.                   gnss-TOD-msec-r10 '353D20'H
41.                 }
42.               }
43.             }
44.       }
45. }

最终 12:14:15.598006 在1850频点上上报band1 100 ，pci212 小区，才成功切回band1