279934373-6-GSM-Paging-Affecting-Factors-Check-Methods-and-Tools-and-Deliverables-20121031-ppt.ppt

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Huawei Confidential
Security Level:
 Affecting Factors
 Check Methods and Tools
 Deliverables
GSM Paging

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Topics in This Document
Topic Description
Paging
Factors affecting GSM paging success rate
Eight required actions to handle paging problems
Eliminating factors causing GSM paging failures using top problem method and
root cause method
Required documents for submitting a paging problem, including a conclusion made
by using these two methods
Examples used here are typical.

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Date Version Description Reviewer Author
2011-12-31 2011/12
1. Initial issue after
review
Caofei, Chen Ruiqun, Li Yugang,
Liu Kuan, Ni Hongxiang, Xu Binbin,
Xun Lijun, Zhu Kan, Zhang Liang,
Du Jian, Wang Zhicheng, and Qi
Haofeng
Shen Jian,
Wang Lu
2012-10-30 2012/10
1. Paging section
updated
Caofei, Liu Kuan, Ni Hongxiang,
Xu Binbin, Xun Lijun, Zhu Kan,
Zhang Liang, Du Jian, Wang
Zhicheng, Qi Haofeng, Feng
Zhenyan, Chen Jing, and Zhao
Jinjin
Shen Jian,
Zhou
Dong
Change History

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Technical Support
Topic Name ID
Paging
Shen Jian 126759
Wang Lu 165414
We provide 7x24 training services.
The following table lists engineers formulating this document:

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Definition and Measurement Point of Paging Success Rate
Cases
Method for Optimizing Paging Success Rate
General Method for Locating Problems Related to
Paging Success Rate

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Definition of Paging Success Rate
The paging success rate is a counter on the core network. Therefore, this counter
cannot be obtained from the BSS, and must be obtained from the core network. The
measurement object of this counter is LAC. The specific definition is as follows:
Paging success rate = (First paging response times on interface A + Repeated
paging response times on interface A) /First paging request times on interface A

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Measurement Point of Paging Success Rate
The measurement statistics of paging success rate is measured on the core network. The
following figure shows the paging process and measurement point on the BSS.
A: Paging request times
B: Paging response times

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Cases
General Method for Locating Problems Related to Paging
Success Rate

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Classification of Paging Success Rate
Problems
Paging
success rate
problems
Non-compliance of
paging success rate
on the replaced
network
The paging success rate is smaller than that of the original network after replacement. In
this case, perform the following troubleshooting:
1. Check the power match (for details, see Guide to Power Matching During GSM Network
replacement) .
2. Check parameters, including parameter mapping check and check of interconnection
parameters between the MSC and BSC. For details, see intelligent parameter mapping
document and Correlation Analysis of the GSM Wireless Network and Core Network
Parameters.
3. Check whether the LAC division has any change before and after the replacement.
After the confirmation of three preceding points, go to the normal optimization process.
Non-compliance of
paging success rate on
the new network
Go to the normal optimization process.
Suddenly decrease of
the maintenance
network
1. Is there any version update?
2. Is there any parameters change?
After the confirmation of two preceding points, go to the normal optimization
process.
Slowly decrease of
the maintenance
network
1. Rectifying Hardware and Transmission Faults
2. Confirm the season impact.
After the confirmation of two preceding points, go to the
normal optimization process.
Range of
Paging
success rate
problems
Problem of the
whole MSC
Need to optimize the whole MSC.
Problem of TOP
LAC
Optimize top LAC.

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Solution of PSR optimization
Low paging
success rate
Check paging
parameters
NSS parameters:
Paging policy (Paging times, paging duration, TMSI/IMSI flag, and All RAN paging flag) , Implicit IMSI
detach timer (min) , Support pre-paging, Support release before pick-up, Support location update and
optimization, Paging optimization control, and BSC Paging Threshold per Second.
BSS parameters:
Channel Type, CCCH Blocks Reserved for AGCH, Multi-Frames in a Cycle on the Paging CH, Random Access Error Threshold, CS
RACH Min. Access Level, CS RACH Min. Access Level Offset, Minimum Access RXLEV, Paging Times, MS MAX Retrans, SDCCH
Dynamic Allocation Allowed, T3212, A Interface Paging Co-ordination Switch, BSS Paging Co-ordination, and BTS Paging Lifetime.
For details, see the parameter description on the following slide.
Check the paging
overload
Find the top N cells with serious paging overload according to paging-related traffic statistics and flow
control-related traffic statistics, and then perform the troubleshooting. For example, the paging
overload can be avoided by adding extended BCCHs. If the paging overload of the entire network
occurs, you are advised to restart the LAC division.
Check the LAC
planning
In the process of dividing location areas, enlarge the LAC range to reduce the number of LACs under
the prerequisite that the paging overload does not occur. In this way, the times of location updates can
be minimized, and the decrease of unnecessary location updates has a positive impact on the paging
success rate.
Check hardware
and transmission
faults
Find the cells with hardware faults by using the counter R373 Cell Out-of-Service Duration, and then
perform the troubleshooting.
If the ALM-21801 GSM Cell out of Service is reported, perform the troubleshooting according to the
methods of clearing ALM-21801.
Check the
Interference and
coverage problem
Check and resolve the interference problem of TOP N cells.
Check and resolve the poor coverage problem of TOP N cells.
Check BSC/BTS
Version
According to the early warning, notification, release notes, and hitless upgrade tool, confirm whether
the version variances or known problems of the current version affect the paging success rate. For
known causes, take the preventive measures.
Check for abrupt
events
Check whether there are abrupt events such as charging policy changes and mass gathering affecting
the traffic model or Um interface environment.
Check the long-
term traffic trends
Check whether the seasonal trend of changes in PSR, counters, and benchmark data vary with time
segment and whether problems such as traffic change occur due to increasing subscribers.

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Process of Handling Paging Success Rate
Problems
According to the preliminary analysis of the faulty LAC,
determine main factors affecting the paging.
LAC1: cell out of service LAC2: paging overload
LAC3: a large number of poor
coverage areas
LAC4: improper parameter
settings
Perform the hardware and
transmission fault
troubleshooting according
to the troubleshooting
guide.
Solve the paging overload
problem by adjusting the
parameter or LAC.
Perform the following operations
to solve the coverage problem:
Locate the problem point by
drive test, adjust the antenna,
and add BTSs.
Modify the improper
parameters.
According to the traffic statistics analysis of the paging
success rate on the core network, locate the faulty LAC
and the corresponding BSC.
The common paging overload is
BTS overload, that is, the Um
interface overload. In the case of
parameter adjustment, add the
extended BCCH to solve the Um
interface capacity problem.
Focus on engineering adjustments
and constructions with supplemented
parameter optimization. In the case
of parameter adjustment, adjust the
access parameters to reduce the
access restrictions.

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Cases
Paging Success Rate

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Checking Paging–Related Parameters - NSS
Paging–related parameters on the NSS are
as follows:
 Paging times
 Paging duration
 TMSI/IMSI flag
 All RAN paging flag
 Implicit IMSI detach timer (min)
 Support pre-paging
 Support location update and
optimization
 Support release before pick-up
 Paging optimization control
The table on the right lists the parameter
configuration of a certain office.
Office SZS14
BSC SW02A
BSC OPC 2739
LAC 46000255E
Paging
policy
Paging Type = All paging types
Priority = All priorities
Paging times = 3
First paging duration = 6
Second paging duration = 8
Third paging duration = 6
Fourth paging duration = 4
Fifth paging duration = 4
TMSI/IMSI flag = Using TMSI for the first paging
= Using IMSI for the second paging
= Using TMSI for the third paging
= Using TMSI for the fourth paging
= Using TMSI for the fifth paging
All RAN paging flag = The first paging delivered only to the current LAI
= The second paging delivered only to the current LAI
= The third paging delivered only to the current LAI
= The fourth paging delivered only to the current LAI
= The fifth paging delivered only to the current LAI
Implicit IMSI detach timer (min) 66
Support pre-paging No
Support location update and
optimization
Yes
Support release before pick-up Yes

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Adjustment Policy of Paging–Related Parameters - NSS
Parameter ID MO Parameter Name Version Adjustment Policy Priority
LOCUPDT MOD VLRCFG
Implicit IMSI detach
timer (min)
It specifies the time interval when the VLR sets the mobile subscribers to be in IMSI detach state. The unit is minute. The value of the parameter ranges from 1 to
10080. Implicit IMSI detach is originated by networks and explicit IMSI detach is originated by mobile stations. The value of the parameter should be greater than
the time interval of periodic subscriber location update configured on the BSC.
H
PTMR MOD VLRCFG
Subscriber purge timer
(hr)
It specifies the time period before the MSOFTX3000 (VLR) removes or marks the data of inactive mobile subscribers. The unit is hour. The value of the parameter
ranges from 1 to 720. The value of the parameter should be greater than the time interval of periodic subscriber location update configured on the BSC. Generally,
the value of this parameter is 24.
L
FIRSTD MOD PGCTRL First paging duration
The parameter is set to a value greater than the BTS paging lifetime on the BSS. If the value is smaller than the BTS paging lifetime, the MSC delivers the second
paging before the BTS delivers the paging in the paging process. This will increase load of the paging channel. (Refer to Case 1).
H
SECONDD MOD PGCTRL
Second paging
duration
H
THIRDD MOD PGCTRL Third paging duration H
FOURTHD MOD PGCTRL Fourth paging duration H
FIFTHD MOD PGCTRL Fifth paging duration H
TIMES MOD PGCTRL Paging times
It specifies the maximum number of paging times during a paging process. The value range is 1 to 5. A complete paging process refers to the process from
initiating the paging to receiving the paging response or paging failure message.
During a paging process, the maximum duration from initiating the paging to receiving the paging response or paging failure message is 20 seconds by default.
When you set parameters, the summation of the valid duration values should be no more than 20 seconds. For example, if you set Paging times to 3, the
summation of values of First paging duration, Second paging duration, and Third paging duration should be no more than 20 seconds. If you set both First paging
duration and Second paging duration to 10, the system does not initiate the third paging regardless of the value of Third paging duration. Other cases are deduced
in the same way. Two or three of them are required on the live network.
H
ALLRAN MOD PGCTRL All RAN paging flag
It indicates whether the MSOFTX3000 sends paging messages to the specific location area or all the location areas served by the MSC. Enabling the pool-wide
paging may have adverse impacts on the network. Therefore, you are advised to disable pool-wide paging. In a small scale network, the pool-wide paging can be
used to improve the paging success rate under the condition that no paging overload occurs on the BSS.
H
IMSI MOD PGCTRL TMSI/IMSI flag
It specifies whether the TMSI is contained in the paging messages sent by the MSOFTX3000 to the BSC or RNC. The default value is all empty, indicating that
TMSI is used every time.
If the Paging message sent from the MSC to the BSC contains only the IMSI of the MS, the BTS uses the IMSI in the paging message transmitted through the Um
interface. If the MSC sends a Paging message that carries the IMSI and TMSI of the MS to the BSC, the BTS uses the TMSI in the paging message transmitted
through the Um interface.
The IMSI paging can be used to improve the paging success rate under the condition that no paging overload occurs on the BSS.
H
PTPS MOD BSC
BSC Paging Threshold
per Second
It specifies the maximum paging times per second of a BSC. Its value ranges from 10 to 200. By default, the value is 65535, indicating that the MSOFTX3000 does
not perform paging flow control on this BSC. If the value is set to be too small, the MSOFTX3000 performs paging flow control on this BSC.
L
Support pre-paging
If the value of bit4 of P140 is set to 1, the pre-paging is enabled. If the value of bit4 of P140 is set to 0, the pre-paging is disabled. Pre-paging can improve the
efficiency of the incoming call, and shorten the call delay. However, the occupied duration of the SDCCH increases. If the configuration is improper, the congestion
may occur. As a result, the paging success rate decreases.
L
Support location
update and
optimization
If the value of bit1 of P1100 is set to 0, the optimization is enabled. If the value of bit1 of P1100 is set to 1, the optimization is disabled. The default value is 1.
Enabling this function can improve the paging success rate. After the function is enabled, the system effectively makes response to paging in the case of MS
location update.
H
Support release before
pick-up
If the value of bit15 of P166 is set to 0, the function is enabled. If the value of bit15 of P166 is set to 1, the function is disabled. The default value is 1. This bit is
used to control whether to make statistics of the PAGING RESP message in the case of early release. If this function is enabled, the paging response times
increases in the case of the early release of the calling party. In this way, the paging success rate increases.
H
Paging optimization
control
If the value of the bit8 of P164 is set to 0, it indicates that the actual number of paging times is equal to the value of the paging times. If the value is set to 1, it
indicates that the actual number of paging times is equal to the value of the paging times subtracted by 1. If the value of the paging times is 1, there is only one
paging. The default value is 1. If the called party has no paging response in a certain call, the number of paging times is controlled by this parameter in the next call
of this called party. The number of paging times is recovered to the original value when the called party has a paging response. This function is enabled to reduce
times of delivering paging commands by the system when the called party cannot make a response to the paging.
L

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Adjustment Policy of Paging–Related Parameters - BSS
Parameter ID MO Parameter Name
Version
(R11/R12/R13/R14)
Adjustment Policy Positive Impact Negative Impact Priority
CHTYPE GTRXCHAN Channel Type R11, R12, R13, R14
If paging overload of a certain cell is serious, you can configure the extended BCCH to
increase paging capacity. Set TS2 of BCCH TRX to BCH. If more BCHs need to be
configured, you can set TS4 and TS6 of BCCH TRX to BCH.
Paging capacity expansion of the
Um interface can release paging
overload of the Um interface.
Decrease of other channels may
cause congestion of the SD or the
TCH.
H
BSAGBLKSRES
GCELLIDLE
BASIC
CCCH Blocks
Reserved for AGCH
R11, R12, R13, R14
Huawei BTSs support the delivery priority of the immediate assignment messages.
Therefore, the recommended value of this parameter is 1. As a result, more PCHs are
reserved for the paging messages in the case of no immediate assignment messages.
This increases paging channels
and reduces paging overload
probability.
N/A H
BSPAMFRAMS
GCELLIDLE
BASIC
Multi-Frames in a
Cycle on the Paging
CH
R11, R12, R13, R14 The recommended value of this parameter is 2.
This has positive impacts on the
delivery delay of the paging and
the success rate.
N/A L
RANERRTHRED
GCELLCCA
CCESS
Random Access
Error Threshold
R11, R12, R13, R14
The parameter is set to a small value to improve the paging success rate. However, this
may affect the immediate assignment success rate and the congestion rate. Both the
positive impacts and negative impacts must be considered.
The paging success rate is
improved.
The immediate assignment
success rate and the congestion
rate are affected.
H
RACHACCLEV
GCELLCCA
CCESS
CS RACH Min.
Access Level
R11, R12, R13, R14
RACHACCLEV and RACHACCLEVOFFSET determine the CS RACH minimum access
level. The value of RACHACCLEVOFFSET ranges from 0 to 15. The value 0-14 is
corresponding to -8 dB to 6 dB respectively. The default value 15 is corresponding to 0
dB. CS RACH Min. Access Level Offset is set to a small value to improve the paging
success rate. However, this may affect the immediate assignment success rate and the
call drop rate. Both the positive impacts and negative impacts must be considered.
(Refer to Case 2 and 3)
improved.
success rate and the call drop
rate are affected.
H
RACHACCLEVO
FFSET
GCELLSOFT
CS RACH Min.
Access Level Offset
R11, R12, R13, R14
RXMIN
GCELLBASI
CPARA
Minimum Access
RXLEV
R11, R12, R13, R14
The parameter is set to a small value to improve the paging success rate. However, this
may affect the immediate assignment success rate, the call drop rate, and the
congestion rate. Both the positive impacts and negative impacts must be considered.
improved.
success rate, the call drop rate
and the congestion rate are
affected.
L
PAGTIMES
GCELLCCB
ASIC
Paging Times R11, R12, R13, R14
On the condition that no paging overload occurs in cells, the parameter is set to a large
value to improve the paging success rate. The recommended value is 4.
In the case of non-overload of
the paging, setting of the
parameter to a large value can
improve the paging success rate.
In the case of paging overload,
setting of the parameter to a large
value has negative impacts on the
paging success rate.
L
MSMAXRETRAN
GCELLCCB
ASIC
MS MAX Retrans R11, R12, R13, R14
On the condition that RACH overload does not occur in cells, the parameter is set to a
large value to improve the paging success rate.
In the case of non-overload of
the RACH, setting of the
parameter to a large value can
improve the paging success rate.
In the case of overload of the
RACH, setting of the parameter to
a large value has negative
impacts on the paging success
rate.
L
SDDYN
GCELLBASI
CPARA
SDCCH Dynamic
Allocation Allowed
R11, R12, R13, R14
This parameter can be used to improve the low paging success rate due to SDCCH
congestion.
improved.
N/A L
T3212
GCELLIDLE
BASIC
T3212 R11, R12, R13, R14
This parameter is set with the consideration of the implicit IMSI detach timer on the core
network side. The value of the timer on the BSS must be smaller than the value of the
timer on the NSS. In addition, value of the timer of the cells in the same LAC needs to
be set to the same value.
improved.
N/A H
ACOOPERATPA
GINGSWITCH
BSCPSSOF
TPARA
A Interface Paging
Co-ordination Switch
R11
You are advised to turn on the two switches at the same time. In this way, the BSC with
the built-in PCU can make response to CS paging of MSs when MSs implement PS
services. The paging success rate is improved. The A interface paging co-ordination
switch is deleted in versions later than R12 and only the BSS paging co-ordination
switch is reserved.
improved.
N/A H
BSSPAGINGCO
ORDINATION
GCELLPSBA
SE
BSS Paging Co-
ordination
R11, R12, R13, R14
29
GCELLBTSS
OFT
BTS Paging Lifetime R11, R12, R13, R14
The value of the BTS software parameter 29 ranges from 0 to 255. The unit is 250 ms.
By default, the value is 255, corresponding to 5s. When setting this parameter, consider
the coordination with the first paging duration of the parameter on the core network. If
this value needs to be smaller than the first paging duration on the core network,
preferentially set the first paging duration on the core network to a large value.
improved.
N/A H

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Analyzing Paging Delay Distribution
Prerequisite
The Trace Analyzer on the core network
must be based on Huawei MSC.
Principle
The Trace Analyzer on the core network exports the delay
statistics according to the A interface signaling, and the
setting of paging strategy parameters on the core network
can be optimized. The principle is as follows:
 The sum of n times paging intervals on the core
network must be larger than the most paging response
delay (for example, 97%-98%).
 For the network in which the Um interface delivery
capability becomes a bottleneck, the increase of the
paging interval can reduce the repeated paging
delivery. In this way, the impact of repeat paging
delivery on the Um interface can be reduced.
Note: This is a part of the parameter optimization, which
serves as a reference for the paging duration
optimization.
For details, see Case 4 Core Network Tool Application.
You can obtain the tool at the following website:
http://support.huawei.com/support/pages/editionctrl/catalog/ShowSoftDetail.
do?actionFlag=displaySoftInfo&node_id=000001505811&web_doc_id=SW0
000405465&colID=ROOTWEB|CO0000000065
GSM paging delay distribution
Times
Time (second)

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Impact
The paging volume exceeds the processing capability of the BSC. As a result, the BSC discards
the paging.
Check Method
BSC6000 check method (taking the CS paging as an example)
A0300 + A0301 > A032, or A032 > ∑A330 (averaging the counters of cells in the same LAC and
taking the sum of the averaged counters of several LACs)
BSC6900 check method (taking the CS paging as an example)
A0300 + A0301 > ∑A330 (averaging the counters of cells in the same LAC and taking the sum of
the averaged counters of several LACs)
Solution
1. The CPU load is heavy on the XPU board. If the value exceeds 85% of the standard load, the
flow control starts. You are advised to adjust the BTS to balance the CPU usage.
2. Increase Max CS Paging Message Num in Period and Max PS Paging Message Num in
Period. For details, see Case 5 BSC Discard.
3. The LAC is incorrectly configured on the core network. As a result, the paging messages are
incorrectly delivered to this LAC. You are advised to check the configuration of the core
network.
4. Perform the BSC capacity expansion and reduce the number of local areas in the BSC.
Troubleshooting Paging Overload - BSC Discard

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Impact
The LAPD link between the BSC and BTS is congested or unavailable. As a result, the paging
message is discarded.
Check Method
A531: CS Pagings Discarded on LAPD Link > 0
A532: PS Pagings Discarded on LAPD Link > 0
Solution
1. Enable the Cell Paging Package Switch (for the BTS version support, see "Paging Problems"
on Slide 28).
2. When the delay of the Abis transmission is large, change RSL LAPD Window Size from 4 to 8.
3. For the large paging volume cell, change Multiplexing Mode of the corresponding site to 2:1 or
1:1. If this configuration cannot be performed successfully due to deficient transmission
resource, you are advised to perform the transmission capacity expansion for the Abis interface.
Troubleshooting Paging Overload -
LAPD Discard
In R11 and R12, these two
counters are the internal
counters which cannot be
queried by PRS. In addition,
the two counters can be
exported by using the OMstar
or performance browse tool.

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Impact
There are too many paging messages. They exceed the paging message transmitting threshold of
the Um interface on the BTS. As a result, the BTS discards the paging message.
Check Method
A337: Number of Deletions of the Paging for CS Services on the PCH >> 0, or A338: Number of
Expiries of the Paging for CS Services on the PCH >> 0
A339: Number of Deletions of the Paging for PS Services on the PCH >> 0, or A340: Number of
Expiries of the Paging for PS Services on the PCH >> 0
For the Huawei network, the common paging processing capability of the Um interface is 200,000
times/hour (according to different traffic models, this value may be different). If the value exceeds
200,000 times/hour, check the paging overload condition immediately.
Solution
1. Configure the extended BCCH. For details, see Case 6 BTS Discard.
2. Split the LAC area.
Troubleshooting Paging Overload -
BTS Discard

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Troubleshooting Paging Overload - SDCCH
Congestion
Impact
The paging has no response due to the SDCCH congestion.
Check Method
ZTR103A: Congestion Rate on SDCCH per BSC
ZK3001: Failed SDCCH Seizures due to Busy SDCCH per BSC
The preceding two counters are large.
Solution
1. Filter the top N cells with continuous congestion according to the cell-level counter RR370
Congestion Rate on SDCCH per CELL (due to Busy).
2. Add static SDCCHs to handle the SDCCH congestion.
3. Expand the capacity of the TRX board and configure the SDCCH.
4. In versions later than R13, configure Num of TSs Convertible to SDCCHs per TRX to reduce
the SDCCH congestion.
5. For the SDCCH congestion caused by a large number of location updates, the LAC border
adjustment must be considered, instead of only adding SDCCHs.

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Principle
In the process of dividing location areas, enlarge the LAC range to reduce the number of LACs
under the prerequisite that the paging overload does not occur. In this way, the times of location
updates can be minimized, and the decrease of unnecessary location update has a positive
impact on the paging success rate.
LAC Area Assessment
1. Capacity:
In the case of no extended BCCH, the paging load capability of a location area is 50 times/s
(the peak of the paging volume cannot exceed this value in the LAC).
In the case of extended BCCHs, the paging load capability of a location area can be
calculated as follows: 50 times/s x (1 + Number of extended BCCHs).
Reduce the number of LACs if only the capacity requirement can be met.
2. Border reasonableness:
The LAC border should not be planned in areas with large passenger flow volume. The LAC
crossed by the main traffic lines such as expressways and railways should be as few as
possible; therefore, a large number of unnecessary location updates are avoided.
For details, see Case 7 "Planning the LAC ".
Planning the LAC

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Impact
The paging messages cannot be processed or delivered due to hardware or transmission
faults.
Check Method
R373: Cell Out-of-Service > 0
CA306: Timeouts Waiting MSC's CC Message > 0
ALM-21801: GSM Cell out of Service
Rectifying Hardware and Transmission Faults
Solution
To rectify the hardware and transmission
faults,
perform the troubleshooting according to
the methods of alarm ALM-21801.
You can obtain the alarm description from
HEDEX.

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Cases
Paging Success Rate

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Adjust the paging duration of the core network on the Erdos entire network, and the paging success rate is improved by
0.4%.
Promotion in phase 1: At 11:00, change the paging duration of 14 LACs from 6/5/4 to 6/6/5.
Promotion in phase 2: At 4:00, change the paging duration of 14 LACs from 6/6/5 to 6/6/6.
Conclusion: By modifying the paging duration of the core network, the paging success rate is improved by 0.4%.
Phase 1: The whole paging success rate is
improved by 0.3%.
Case 1 Parameter Optimization
Phase 2: The whole paging success rate is
improved by 0.1%.

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Paging success rate tendency
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September
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Entire network
Adjust the access parameters on the Erdos entire network, and the paging success rate is improved by 0.3%–0.4%.
Random Access Error Threshold: Change the value larger than 180 to 180.
CS RACH Min. Access Level: For GSM900 cells, set this value to –109. For GSM1800 cells, set this value to –105.
Minum Access RXLEV: For GSM900 cells, set this value to 10. For GSM1800 cells, set this value to 15.
Conclusion: After the whole wireless access parameter optimization, the paging success rate of the entire network is
improved by 0.3%–0.4%. The TCH call drop rate increases by 0.01%, and other KPIs have no change.

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CMCC adjusts parameters related to the BSS and NSS. The paging success rate is improved by 2%.
Conclusion: The paging success rate is improved by 2% after the paging parameter optimization on both the BSS and NSS.
Parameter
Name
Current
Value
Recommended
Value
Modification Reason
Send System
Information 2ter
No Yes
The system 2ter message is not sent, which affects the MS reselection
between the 900 MB cell and 1800 MB cell in idle state.
Minimum
Access RXLEV
10 8
Because the coverage of BSC 3B1 is not the main urban area and the
distance between BTSs is 5 Km, you are advised to set this parameter
to a small value and widen the restriction of MS camping on the cell.
According to the preceding experience, a small value of this parameter
has a positive impact on the paging success rate.
RACH Min.
Access Level
-109 -112
Because the coverage of the BSC is not the main urban area and the
distance between BTSs is 5 Km, you are advised to set this parameter
to a small value and widen the restriction of MS access. According to
the preceding experience, a small value of this parameter has a
positive impact on the paging success rate.
Paging times 2 6
Some paging messages on the BTS are deleted currently by querying
the traffic statistics. The hardware fault occurs in cell 7 and cell 79, and
no paging is deleted in the other site. Therefore, to increase the paging
retransmissions can improve the paging success rate.
MS MAX
Retrans
4 7
Because the BTS Paging Lifetime is set to a large value of 7s, and no
paging overload of the uplink RACH occurs, you are advised to set MS
MAX Retrans to a large value to improve the paging success rate.
Paging times
(MSC side)
2
3 (first paging
TMSI+LAC, second
paging IMSI+LAC,
third paging
IMSI+LAC)
Enable three times paging to improve the paging success rate under
the condition that no paging overload occurs.
First paging
duration (MSC
side)
6s 8s
The BTS software parameter is 29, that is, BTS Paging Lifetime. To
optimize the TBF setup success rate, set the software parameter from
255 to 28, that is, from 5s to 7s. However, the interval between first
paging and second paging on the core network is set to 6s. According
to the recommended configuration, BTS Paging Lifetime should be
smaller than the paging interval of the core network. Otherwise, the
paging queue resources on the BTS are wasted. The paging interval of
the core network is set to (6, 8). That is, the first paging duration is 6s,
and the second paging duration is 8s. Set the first paging duration to a
large value that is greater than BTS Paging Lifetime. In this way, the
first paging success rate can be improved, and the paging overload
probability on the BSS is reduced.

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Times
Time (second)
The paging interval of the original core network (3, 3):
 The summation of two paging intervals is small. As a result, some
of them send paging response messages. If the interval exceeds
the paging lifetime of the core network, the measure fails.
 A large number of second paging messages are retransmitted.
Actual network conditions: The delivery capability is a bottleneck,
and the paging overload occurs.
The paging interval of the core network after optimization (10, 3):
 Most of paging responses are measured.
 The paging retransmission and paging flow control are
reduced.
Actual network conditions:
The paging success rate is improved from 50% to 90%.
Case 4 Core Network Tool Application
The paging success rate of a certain office in Philippines is improved by adjusting the paging interval.
Typical LAC: 41022 2011-11-2 2011-11-3 2011-11-23 2011-11-24
First paging
delivery times
10:00 109427 103110 76127 74887
19:00 180343 182447 151361 156693
Paging success
rate
10:00 83.30% 82.70% 92.20% 92.10%
19:00 75.40% 68.30% 90.00% 90.00%
First paging
success rate
10:00 78.50% 78.30% 90.00% 89.80%
19:00 60.40% 47.60% 87.00% 86.80%
Total paging
delivery times
10:00 132860 125487 83735 82479
19:00 252229 280329 170971 177261
Times
Time (second)

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Low paging success rate
The paging volume delivered by A interface exceeds the threshold of the BSC due to traffic increase, and a large number
of paging messages are discarded by the BSC. As a result, the paging success rate is low and the retransmitted paging
messages increase abruptly.
Case 5 BSC Discard
BSC version: BSC6000V9R8C12SP25
 CS paging received by the A interface:
A0300 = 2071150
A0301 = 0
 CS paging delivered by the Abis
interface:
∑A330 = 1101831
 Average BSC discarding CS paging is
equal to 969319.
 Solution: Change Max CS Paging
Message Num in Period from 160 to
330, and the BSC discarding paging
disappears.
BSC configuration:
Max CS Paging Message Num in Period is 160.
The following figure shows the configuration of signaling link 7 on the
A interface. Two signaling links 7 on the A interface are in subrack 0
(BM) to subrack 6 (TC) and subrack 3 (BM) to subrack 7 (TC)
respectively.
Note:
The paging message arrival rate is configured based on the CPU. As
shown in the following figure, two A interface signaling links are
bound in different subracks. Therefore, they do not share the same
CPU. Each CPU allows 160 paging messages per second.
The maximum paging volume allowed by a BSC in an hour is
1152000 (160 x 3600 x 2 = 1152000).
The following table lists parameter
values of two networks.
Office
BSC
Name
CS Paging
Volume on the
A Interface
Average Paging
Volume Delivered by
the Abis Interface:
∑A330
Average BSC
Discard:
A0300+A0301-
∑A330
Paging
Success Rate
of the Core
Network
A0300 A0301
Indonesia
XL
BLMP7 2071150 0 1101831 969319 38.23%
Erdos BSC17 105625 0 105620 5 98.30%

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Low paging success rate in XXX network
After a new BTS is configured for a BSC, the paging volume exceeds the paging capacity limitation of the Um interface,
and a large number of paging messages are discarded by the BTS. As a result, the paging success rate is low and the
retransmitted paging messages increase abruptly.
Case 6 BTS Discard
BSC version: BSC6900V900R011C00SPH732
 CS paging delivered by the Abis interface:
Average A330 = 361797
The paging volume delivered by the Abis interface exceeds the paging capacity limitation of the Um interface.
 Paging discarded by the BTS:
A337 = 69626
A338 = 118319
A339 = 1001
A340 = 105
 Solution: Configure the extended BCCH for all cells. The paging success rate is recovered rapidly.
The following table lists parameter
values of two networks.
Office
BSC
Name
Paging Volume Discarded by
the BTS Paging Success Rate
of the Core Network
A337 A338 A339 A340
Uganda —— 69626 118319 1001 105 43.36%
Erdos BSC17 0 0 0 0 98.30%

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XXX network LAC area planning assessment
Select top N cells of the location update by filtering cells in the LAC borders.
Green circle: This circle covers three
LACs at the provincial road border. This
symptom is abnormal. The preliminary
adjustment plan is required.
Brown circle: This circle covers the
urban area or the Banner and county
centers with a high density of population.
There are many location updates in this
circle, and this is normal.
Blue circle: This circle covers the border
between the LAC area and Baomao
Expressway. The expressway is close to
the LAC border, and this configuration
must be optimized later.
Case 7 Planning the LAC

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In XXX network, some BSCs have low PSR due to MSC SPF board overload.
Case 8 MSC SPF board overload
Time GBSC Integrity
CA306: Timeouts
Waiting MSC's CC
Message
09/07/2012 20:00 BSC_Cirebon_2 100% 446680
09/07/2012 20:00 BSC_Indramayu 100% 244420
We can monitor the counter
CA306 to find out if the SPF
board with high load.
After the expansion of SPF
board, PSR became normal.

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Problem Cause Solution
The power is not
matched after
network
replacement in
Philippines with the
high SD traffic
volume and
occurrence of
paging overload.
1. The replacement power is not matched. As a
result, the LAC paging volume is larger than
that of the original network, and the paging
request is replaced by the immediate
assignment command. The paging overload
occurs.
2. Other factors: SD congestion, interference from
an external source, interference of engineering
intermodulation, and paging flow control
1. Power matching
2. Paging policy matching: disabling AGCH
priority
3. Performing configuration according to the new
SD configuration rules
4. Replacement analysis, large paging volume
LACs configurable with the extended BCH and
AGCH
5. Sufficient expansion of transmission resources
AGCH Mapping SD Reconfigure
and Traffic Balance Paging Duration Extend
In the large traffic volume environment in XXX network, the paging overload occurs because the
paging volume exceeds the Um interface capacity after replacement.
Case 9 Paging Overload in XXX network

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In XXX network, it is MSC pool scenario, some BSCs with 0% PSR due to
wrong NRI configuration:
Case 10 configuration problem in MSC pool
In MSC pool
scenario, the NRI
configuration of
BSS should be the
same with NSS.
BSC SWLD2 &
SWWV3 with
0% PSR

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Attachment 1 Analysis Report on Paging
Problems

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Attachment 2 Required Actions Related to
Paging Problems
Required Actions Related to
Paging Problems checklist
Operation
Range
Description Application Scenario Operation Analysis
Classifying problems related to
paging success rate
Entire network Specify the current paging problem.
Specify current problems, for example, non-compliance of network paging success
rate, degradation of NE paging success rate after upgrade, increase of live
network paging success rate.
Checking power matching
(applicable to non-compliance of
network paging success rate)
Entire network
Check power matching by using the power matching
tool.
replacement
Check the power matching before and after the upgrade according to contents in
the Power Matching Guide and the Power Matching Tool.
Checking parameters (applicable
to non-compliance of network
paging success rate)
Entire network
Check the parameter mapping before and after the
upgrade and checking parameters related to
interconnection of NSS and BSS.
replacement
Check parameter mapping results of the live network and the original network
according to the intelligent parameter mapping tool and verify parameters related
to interconnection of MSC and BSC according to Correlation Analysis of the GSM
Wireless Network and Core Network Parameters.
Checking parameter inheritance
(applicable to degradation of NE
paging success rate after upgrade)
Entire network Compare parameters before and after the upgrade. Upgrade
Compare MML script files before and after the upgrade by using the PFMStudio to
find different parameter setting.
Comparing different versions
(applicable to degradation of NE
paging success rate after upgrade)
Entire network
Verify the existing information to confirm the version
variances before and after the upgrade.
Upgrade
Confirm whether the version variances or known problems of the current version
affect the paging success rate according to the early warning, notification, release
notes, and hitless upgrade tool. For known causes, take the preventive measures.
Troubleshooting hardware and
transmission faults
Entire network
Find out and rectify hardware and transmission faults
according to analysis of traffic statistics and alarms.
Deployment,
replacement, upgrade,
and inventory
Analyze traffic statistics (R373: Cell Out-of-Service Duration) and the alarm (ALM-
21801: GSM Cell out of Service) to find out cells with hardware or transmission
faults and then analyze the cell according to the methods of clearing alarms.
Troubleshooting paging overload
Entire network
and top N cells
Analyze paging overload of the BSC according to the
traffic statistics.
Deployment,
and inventory
Analyze related traffic statistics to find out bottleneck of the paging overload and
then perform corresponding operations to solve the problem.
Planning the LAC area Entire network Analyze capacity of the LAC and the LAC border.
Deployment,
and inventory
1. Use the LACs to reduce the number of LACs if the paging volume is low.
2. Analyze the LAC border based on the engineering parameters and the digital
map. The LAC border should not be planned in areas with large passenger flow
volume. The LAC crossed by the main traffic lines such as expressways and
railways should be as few as possible; therefore, a large number of
unnecessary location updates are avoided.
Analyzing cells with poor coverage
and paging black holes
Entire network
and top N cells
The core network tool searches the cells which have
activities such as short messages, call, location
update, and paging in the recent several minutes
according to the IMSI of no paging response in the
call logging to find the black hole cells. The analysis
can be implemented manually combined with the
coverage diagram output by OMstar.
Deployment,
and inventory
1. Use the Trace Analyzer tool to filter the paging black hole cells.
2. Use the OMstar tool to output the coverage diagram.
3. Use the two tools to find the poor coverage points of paging black hole cells,
pass the test of border roads, and investigate the on-site wireless environment.
Based on the different reasons, you can optimize the cells.
Checking paging-related
parameters
Entire network
Troubleshoot parameters that may affect paging,
including parameters on the BSS and parameters on
the core network.
Deployment,
and inventory
Provide settings of paging-related parameters on the live network, including
parameters on the BSS and parameters on the core network, and then optimize
and adjust the parameters according to contents in the slide.
Troubleshooting known version
problems
Entire network Troubleshoot known version problems.
Deployment,
and inventory
Troubleshoot the known version problems mentioned in the slide.

279934373-6-GSM-Paging-Affecting-Factors-Check-Methods-and-Tools-and-Deliverables-20121031-ppt.ppt

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