14 gsm bss network kpi (call setup time) optimization manual[1].doc

GSM BSS Network KPI (Call Setup Time) Optimization Manual INTERNAL
Product Name Confidentiality Level
G3BSC INTERNAL
Product Version Total 27 pages
GSM BSS Network KPI (Call Setup Time)
Optimization Manual
For internal use only
Prepared by Yang Chunjie (ID: 00119951) from
the GSM&UMTS Network
Performance Research Dept.
Date 2008-12-24
Reviewed by Date yyyy-mm-dd
Reviewed by Date yyyy-mm-dd
Approved by Date yyyy-mm-dd
Huawei Technologies Co., Ltd.

Contents
1 Overview of the Call Setup Time........................................................................7
1.1 Definition of the Call Setup Time.................................................................................................7
1.2 Recommended Formulas...............................................................................................................7
1.3 Signaling Procedure and Measurement Points..............................................................................8
2 Influencing Factors..............................................................................................10
2.1 Procedure Configuration.............................................................................................................10
2.2 Parameter Settings.......................................................................................................................10
2.3 Routing........................................................................................................................................10
2.4 Hardware, Transmission, Coverage, and Interference................................................................11
3 Analysis Process and Optimization Method..................................................12
3.1 Analysis Process..........................................................................................................................12
3.2 Process Description.....................................................................................................................13
3.2.1 Procedure Configuration.......................................................................................................13
3.2.2 Parameter Setting..................................................................................................................15
3.2.3 Routing..................................................................................................................................18
3.2.4 Hardware, Transmission, Coverage, and Interference..........................................................19
4 Test Method...........................................................................................................21
5 Optimization Cases..............................................................................................22
5.1 Long Call Setup Time Due to Long Period of Assignment Command Delivery........................22
5.1.1 Problem Description.............................................................................................................22
5.1.2 Problem Analysis..................................................................................................................22
5.1.3 Suggestion and Summary......................................................................................................22
5.2 Long Call Setup Time Due to Reporting of Two Classmark Change Messages........................23
5.3 Long Call Setup Time Due to Calling and Called MSs Under Different MSCs........................24
2014-6-18 Huawei Proprietary and Confidential Page 3 of 27

5.4 Long Call Setup Time Due to Inconsistency in Signaling Procedures.......................................25
6 Information Feedback.........................................................................................27

Revision Record
Date Revision Change Description Author
2008-12-24 V0.3 Draft completed. Yang Chunjie
2009-1-20 V1.0 This document is modified
according to review comments.
Yang Chunjie
References
SN Document Author Date
1 GSM BSS Network KPI
(Call Setup Time) Baseline
Wu Zhen 2007-08-24
2 GSM Call Setup Time
(CS) Analysis Report
Zha Shuangliu, Li
Xiaomeng, Zhang Lida,
and Wu Baishan
2008-10-25

GSM BSS Network KPI (Call Setup
Time) Optimization Manual
Keywords
Call setup time
Abstract
This document describes the method of optimizing the call setup time.
Acronyms and Abbreviations
MOC Mobile Originated Call
MTC Mobile Terminated Call
PSTN Public Switched Telephony Network
TMSI Temporary Mobile Station Identity

1 Overview of the Call Setup Time
1.1 Definition of the Call Setup Time
The call setup time indicates the mean time from the originating of a call by a
subscriber to the setup of the call. A long call setup time will severely affect
the user experience. Therefore, the call setup time is one of the KPIs that
operators are most concerned about.
1.2 Recommended Formulas
The call setup time is obtained through drive tests. It refers to the time for an
MS to set up an end-to-end call through radio network equipment. There are
three types of call setup time:
 MS to PSTN: average interval between the transmission of the Channel
Request message from the MS and the MS's reception of the Alerting
message sent from the MSC
 MS to MS: average interval between the transmission of the Channel
Request message from the calling MS and the calling MS's reception of
the Alerting message sent from the MSC
 PSTN to MS: average interval between MS's receiving of the paging
message from the MSC and sending of the Alerting message from the
MS to the MSC
Note that the call setup time is the average setup time of multiple successful
calls. You need to conduct multiple dialing tests.

1.3 Signaling Procedure and Measurement Points
Figure 1.1 Measurement points in an MOC setup procedure (with the early
assignment procedure as an example)
BTS BSC
Channel Request
Channel Requi r ed
Channel Act i ve
Channel Act i ve
ACK
I mmedi at e Assi gnment Command
SABM
UA
Est abl i shed
I ndi cat i on
CR
CC
CM Ser vi ce Accept ed
Set up
Cal l Pr oceedi ng
Assi gnment
RequestChannel Act i ve
Channel Act i ve
ACK
Assi gnment Command
SABM
UA
Est abl i shed
I ndi cat i on
Assi gnment Compl et e
Assi gnment
Compl et e
A
B
MS
Al er t i ng

Figure 1.2 Measurement points in an MTC setup procedure (with the early
assignment procedure as an example)
MS BTS BSC MSC
Channel Request
Channel Requi r ed
Channel Act i ve
Channel Act i ve
ACK
I mmedi at e Assi gnment Command
SABM
UA
Est abl i shed
I ndi cat i on
CR
CC
CM Ser vi ce Accept ed
Set up
Cal l Cont r ol
Assi gnment
RequestChannel Act i ve
Channel Act i ve
ACK
Assi gnment Command
SABM
UA
Est abl i shed
I ndi cat i on
Assi gnment Compl et e
Assi gnment
Compl et e
Al er t i ng
C
D
pagi ng
Pagi ng Command
Pagi ng Requi r ed
In Figure 1.1 and Figure 1.2:
 A is the time when the MS sends a Channel Request message.
 B is the time when the MS receives the Alerting message from the MSC.
 C is the time when the MS receives a paging message.
 D is the time when the MS sends an Alerting message.
In the tests of MS-to-MS or MS-to-PSTN calls, the call setup time is equal to
B minus A; in the tests of PSTN-to-MS calls, the call setup time is equal to D
minus C.

2 Influencing Factors
2.1 Procedure Configuration
The setup of either an MOC or an MTC involves many procedures such as
authentication and ciphering mode setting and relates to multiple NEs such as
the MSC, BSC, BTS, and MS. Therefore, the configuration of the call
procedures directly determines the length of the call setup time.
2.2 Parameter Settings
The call setup time is related to the entire procedure of an MOC or MTC, and
therefore, many parameters can affect the call setup time.
The following are some examples:
 BS-PA-MFRAMS
 Use Imm_Ass Retransmit Parameter
 Max Delay of Imm_Ass Retransmit and Max Transmit Times of
Imm_Ass
 Pre-paging function, which is set on the MSC
 Immediate Assignment Opt.
 ECSC, which means early classmark sending control
 Allow Reassign
 Late assignment function, which is set on the MSC
 Assignment command optimization
 Force Queue In Assignment
 T11(s)
2.3 Routing
The network equipment of different manufacturers varies. Therefore, in the
case of interworking between equipment of different manufacturers or change
in routing, analysis and handling should be performed, on the basis of drive
test results.

2.4 Hardware, Transmission, Coverage, and
Interference
A problem in hardware, transmission, coverage, or interference may result in
an increase in the call setup time.

3 Analysis Process and Optimization
Method
3.1 Analysis Process
Figure 1.1 Analysis process
Call setup time
too long
Collect the test
data
Is it due to a problem
in parameter settings?
Is it due to a
problem in routing?
Analyze the problem
based on the signaling
and data configuration
and take proper measures
Is the problem
solved?
End
Yes
Yes
Yes
Yes
No
No
No
Is it due to a problem in
procedure configuration?
No
Optimize the procedure
configuration and then
verify the optimization
Adjust the parameter
settings and then
verify the adjustment
Is it due to a problem in
hardware, transmission,
coverage, or
interference?
Solve the problem
according to the related
optimization manual
Yes
No

3.2 Process Description
3.2.1 Procedure Configuration
During the setup of a call, some procedures are optional, such as
authentication, ciphering mode setting, and TMSI reallocation, and
independent of each other. Therefore, flexible configuration of the procedures
according to operators' requirements is applicable.
On the existing networks, ciphering is generally enabled, and authentication
and TMSI reallocation are enabled on a proportion (that is, 10% to 20%) of
MSCs.
Authentication
For a 3G subscriber, during the authentication when the mobile accesses a
GSM network, the MSC sends an authentication message to the mobile. The
message contains the RAND, AUTN, and RES, and is longer than 23 bytes.
Therefore, the LAPDm needs to divide the message into two and deliver them
separately.
Thus, in a GSM network, a 3G subscriber requires 240 ms to 260 ms more
than a 2G subscriber in terms of the call setup time.
In addition, when the BSC assigns an AMR channel, the Assignment
Command message will be longer than 23 bytes if the frequency hopping MA
is too long. This results in 240 ms to 260 ms more in the call setup time.
Ciphering Mode Setting
During the setup of an MOC, if the ciphering mode setting procedure is not
performed, the MS does not send a Setup message until it receives a CM
Service Accepted message from the MSC; if ciphering is to be enabled,
however, the MS can send a Setup message immediately after the ciphering
mode setting procedure is performed.
Therefore, for an MOC, the call setup time in the case of ciphering enabled is
generally only 250 ms to 300 ms longer than the call setup time in the case of
ciphering not enabled. This is because the MS sends one more message (that
is, the Ciphering Mode Complete message) to the network in the case of
ciphering enabled.
TMSI Reallocation
The TMSI is reallocated according to the settings on the network side after
each operation or several operations on the air interface, such as a call or a
location update.
Classmark Enquiry
The Core Network (CN) can obtain the MS's information about their
multiband and multislot capabilities through the classmark enquiry procedure.

At the BSS, the cell-oriented parameter ECSC is set. The BSS sends the
parameter through the system information type 3. Once an MS accesses the
network, the MS reports Classmark3. According to the protocol, this must be
implemented at MSs that support multiband, multislot, and Voice Group Call
Service (VGCS).
In practice, competitors generally do not enable classmark enquiry in their
CNs but use ECSC. Thus, the LAPDm signaling interaction on the air
interface is reduced, and the call setup time is shortened. Huawei, however,
enables classmark enquiry in all its CNs by default. In addition, the classmark
enquiry is not user-configurable. It can be controlled by the related reserved
software parameter only.
Therefore, when ECSC is enabled at both competitor's BSS and Huawei BSS,
Huawei CN results in at least 240 ms more than competitor's CN in terms of
the call setup time. For specific cases, see sections 5.2"Long Call Setup Time
Due to Reporting of Two Classmark Change Messages" and 5.4"Long Call
Setup Time Due to Inconsistency in Signaling Procedures."
Optimization on I frames at the LAPDm
Before the optimization, Huawei BTS does not support the function of
downlink I frames acknowledging uplink I frames at the LAPDm. That is,
after receiving an uplink I frame from an MS, the BTS immediately sends an
RR response message to the MS. During this process, if the BTS receives a
downlink I frame from the BSC, the BTS has to postpone the delivery of the
downlink I frame, that is, the BTS sends the downlink I frame in the next
delivery period. Thus, the delay increases. This problem can be solved after
the upgrade.
With the optimization, the BTS can acknowledge uplink I frames by downlink
I frames. That is, after receiving an uplink I frame from an MS, the BTS does
not send an RR frame immediately. Instead, the BTS waits a period of time
and checks whether it receives a downlink I frame. If the BTS receives a
downlink I frame during this period, it acknowledges the uplink frame by the
downlink I frame. Thus, the delay is decreased by one delivery period.

Figure 1.1 shows the effect of the optimization.
Figure 1.1 Optimization on I frames at the LAPDm
The optimization can be achieved by BTS upgrade only. It is incorporated into
V300R008C11B337 of the BTS. During the optimization on the call setup
time on site, the optimization on I frames can be considered.
3.2.2 Parameter Setting
The main parameters that affect the call setup time are as follows:
 BS-PA-MFRAMS
This parameter specifies the number of multi-frames used as a unit of the
paging sub-channel.
If this parameter is set to a high value, the average paging delay is great.
Thus, the MS-to-MS call setup time and the PSTN-to-MS call setup time
are prolonged.
 Use Imm_Ass Retransmit Parameter
If this parameter is set to Yes, the BSC sends the immediate assignment
retransmission parameter to the BTS. Otherwise, the BSC does not send
the immediate assignment retransmission parameter to the BTS.
The immediate assignment retransmission function can help increase the
call completion rate of MSs but may increase the access delay of MSs
and the load of the BSC.
It is recommended that this function be disabled.
 Max Delay of Imm_Ass Retransmit and Max Transmit Times of
Imm_Ass
These two parameters specify the maximum delay of the immediate

assignment retransmission and the maximum number of immediate
assignment retransmissions respectively.
When the network quality is poor, an immediate assignment message
may need to be retransmitted. If these parameters are set to high values,
the average call setup time may be prolonged.
 Pre-paging function
This parameter is set on the MSC.
− If the pre-paging function is enabled, the MSC pages the called party
as soon as the MSC receives the Setup message from the calling
party.
− If this function is not enabled, the MSC pages the called party as soon
as the MSC sends the Call Proceeding message.
Therefore, for MS-to-MS calls, the call setup time can be shortened if the
pre-paging function is enabled.
It is recommended that this function be enabled.
 Immediate Assignment Opt.
The channel activation and immediate assignment commands are sent at
the same time to accelerate the signaling processing, thus improving the
response speed of the network.
It is recommended that this function be enabled.
 ECSC
This parameter specifies whether the MSs in a cell use early classmark
sending.
− If this parameter is set to Yes, after a successful immediate
assignment, the MS sends additional classmark information to the
network as early as possible.
− For dual-band MSs, if this parameter is set to No, the MSC sends a
Classmark Request message after the MS reports an Establish
Indication message. The MS then reports the Classmark Update
message. The access delay of the MS is affected.
 Allow Reassign
If this parameter is set to Yes, the BSC initiates a reassignment when
receiving an assignment failure message over the Um interface. This
helps increase the call completion rate and improve the QoS of the
network. The successful reassignment, however, results in an increase in
the access delay of MSs and the load of the BSC.
 Late assignment procedure
This parameter is set on the MSC. With the late assignment function, the
assignment command is sent after alerting. This can shorten the call
setup time. In the late assignment procedure, however, the reception of
the Alerting message does not necessarily indicate the establishment of a
call. Therefore, the call setup time is not measured in the late assignment
procedure.
 Assignment command optimization

If frequency hopping is enabled at Huawei BTS, the ARFCNs in the
assignment command are delivered in the form of CA+MA by default,
which may result in the assignment command longer than 23 bytes.
Then, the message is divided into two I frames at the LAPDm, which are
delivered separately. Thus, the delay is increased by about 230 ms
because of the addition of a delivery period.
To shorten the call setup time, the ARFCNs can be delivered in the form
of frequency list so that the assignment command can be delivered in one
I frame.
On live networks, the frequency list mode is recommended. Figure 1.1
describes how to set this parameter.
Figure 1.1 Setting of the assignment command optimization parameter
Parameter Setting Decrease in
the Delay
Assignment
command
optimization
parameter
Bit 1 of the cell-
oriented reserved
parameter 1 is 1,
that is, the
parameter value is
65535.
CA+MA No
Bit 1 of the cell-
oriented reserved
parameter 1 is 0,
that is, the
parameter value is
65533.
Bit 2 of reserved
parameter 1 is 0, that
is, the parameter value
is 65529.
Frequency list
with the
variable bit map
coding scheme
About
200 ms
Bit 2 of reserved
parameter 1 is 1, that
is, the parameter value
is 65533.
Frequency list
with the bit map
0 coding
scheme
The assignment command optimization is incorporated into BSC6000
V900R008C11B168SP11 and later releases.
For specific cases, see chapter 5"Optimization Cases."
 Force Queue In Assignment
− When this parameter is set to Yes, the BSC puts an assignment
request message into the assignment request message queue if no
TCH is available for assignment, or the BSC assigns a TCH to the
MS if the TCH is available for assignment.
− If this parameter is set to No, the value of queuing allowed indicator
in the assignment request message is 0, which means that the
assignment request message cannot be put into the assignment request
message queue. Then, the channel request is rejected when no TCH is
available for assignment.
The default value of this parameter is No.

 T11(s)
This parameter specifies the length of the timer that is started to wait for
a channel requested by an assignment request message. When the BSC
receives an assignment request but no channel is available for
assignment, the BSC starts the queuing procedure and this timer. If the
channel request is accepted before the timer expires, the timer stops. If
the timer expires, the channel assignment fails.
When queuing is enabled, a high value of this parameter directly leads to
a long call setup time.
3.2.3 Routing
On live networks, when swapping is performed, the BSC and MSC are re-
deployed and thus the call routing changes. Therefore, the setup time of inter-
MSC calls is affected. In this case, tests should be conducted, and the analysis
should be performed on the basis of the test results obtained before and after
the swapping.
For a specific case, see section 5.3"Long Call Setup Time Due to Calling and
Called MSs Under Different MSCs."
Figure 1.2 lists the example values of delay during an MS-to-MS call made in
the lab. On live networks, the delay values are related to the actual situations.
The data in Figure 1.2 is provided only for reference.
Figure 1.2 Example values of delay during an MS-to-MS call made in the lab
Signaling of an Outgoing MS-to-MS Call (Authentication,
Ciphering, and TMSI Reallocation Enabled, Whereas Classmark
Enquiry Disabled)
Relative Delay
(Unit: s)
Channel Request (UL) -> Immediate Assignment (DL) 00.050
Immediate Assignment (DL) -> SABM-CMD (UL) 00.132
SABM-CMD (UL) -> Authentication Request (DL) 00.708
Authentication Request (DL) -> Authentication Response (UL) 00.125
Authentication Response (UL) -> Ciphering Mode Command (DL) 00.564
Ciphering Mode Command (DL) -> Ciphering Mode Complete (UL) 00.000
Ciphering Mode Complete (UL) -> Setup (DL) 00.005
Setup (UL) -> TMSI Reallocation Command (DL) 00.458
TMSI Reallocation Command (DL) -> TMSI Reallocation Complete (UL) 00.001
TMSI Reallocation Complete (UL) -> Call Proceeding (DL) 00.466
Call Proceeding (DL) -> Assignment Command (DL) 00.466
Assignment Command (DL) -> Assignment Complete (UL) 00.011
Assignment Complete (UL) -> SABM-CMD (UL) 00.039

Signaling of an Outgoing MS-to-MS Call (Authentication,
Ciphering, and TMSI Reallocation Enabled, Whereas Classmark
Enquiry Disabled)
Relative Delay
(Unit: s)
SABM-CMD (UL) -> Alerting (DL) 04.797
Total delay 07.822
The versions of NEs used in the test are as follows:
 CN: G9MSC90 MSOFTX3000V100R003
 BSC: V900R008C01B051
 BTS: V3.03R002.20011015
3.2.4 Hardware, Transmission, Coverage, and
Interference
If a TRX or combiner is faulty or if an RF cable is incorrectly connected,
seizing the SDCCH or TCH becomes difficult, and thus the call setup time
increases.
Faults such as poor transmission quality, instability of transport links,
insufficiency of resources, or bit errors on the Abis and A interfaces may lead
to an increase in the error rate on the links, which results in more message
retransmissions between switches. Thus, the message transfer delay increases
and congestion may occur on the links. In severe cases, routes change
frequently, which leads to instability and congestion on the links. If the
preceding problem occurs during call setup, the call setup time increases.
The problem can be identified from traffic statistics. Figure 1.3 lists the
transmission-related alarms at the BSC.
Figure 1.3 Transmission-related alarms at the BSC
Alarm ID Alarm Name
1000 LAPD OML Fault
11270 LAPD Alarm
11278 E1 Local Alarm
11280 E1 Remote Alarm
20081 Loss of E1/T1 Signals (LOS)
20082 Loss of E1/T1 Frames (LOF)
Coverage or interference problems can be identified from the traffic statistics
or KPIs. For example, the interference information can be obtained on the
basis of the interference band distribution in the traffic measurement results. If

a large proportion of interference levels belong to interference bands 3–5, you
can infer that there is strong interference in the uplink. To obtain the downlink
interference information, you can perform drive tests or analyze the traffic
measurement results that are related to receive quality. Strong interference
affects the call drop rate on TCH, the TCH assignment success rate, and the
SDCCH setup success rate, thus affecting the call setup time.
The interference elimination can be classified into intra-network interference
elimination and inter-network interference elimination. For details about
interference elimination, see the G-Guide to Eliminating Interference.
If a coverage problem exists, you can solve the problem by using the methods
such as adjusting the tilt of the antenna, increasing the transmit power, adding
repeaters, and changing the combining mode. For details, see the GSM BSS
Network Performance KPI (Coverage) Optimization Manual.

4 Test Method
The call setup time is one of drive test KPIs. It can be obtained from the
results of call quality tests or drive tests for calls between MSs or between MS
and PSTN.
The method is to perform a short MOC test. During the test, the interval
between two calls is 5s, each call lasts 10s, and the interval between a call
failure and the next call attempt is 30s. The recommended number of calls
during the test is 100. The number of calls can be changed as required. During
the test, the signaling on the Um and A interfaces needs to be traced.
If a value of call setup time is abnormal, analyze the signaling to check
whether the abnormal value is due to failure of the first paging. If the
abnormal value is due to failure of the first paging, do not take this value into
measurement of the call setup time. Otherwise, take this value into the
measurement. Check the signaling on the A interface. If the MSC sends two
Paging messages for one call, you can infer that the first paging for the call
fails.

5 Optimization Cases
5.1 Long Call Setup Time Due to Long Period of
Assignment Command Delivery
5.1.1 Problem Description
After swapping of Ericsson equipment for Huawei equipment at a site, the call
setup time became longer. It was found that the delivery of an assignment
command from Huawei equipment took two or three periods whereas that
from Ericsson equipment generally took only one period.
5.1.2 Problem Analysis
In frequency hopping mode, the BSC6000 currently delivers the ARFCNs in
CA+MA form through the assignment command. CA uses the TV format and
its length is fixedly 17 bytes, and MA uses the TLV format and its length is 3–
10 bytes. If an AMR channel is to be assigned (coded in TLV format in the
command), the length of the assignment command increases by 4–8 bytes.
Thus, the assignment command is longer than 23 bytes. Therefore, at the
LAPDm, the assignment command is divided for delivery. Before the
swapping, however, the ARFCNs are delivered in the form of frequency list,
which uses the TLV format, and therefore in most cases, the assignment
command can be delivered with one frame.
5.1.3 Suggestion and Summary
When setting the assignment command optimization parameter, which is
available only when frequency hopping is enabled in a cell, at the BSC, note
that:
 If this parameter is set to CA+MA, the original Huawei ARFCN delivery
form is retained.
 If this parameter is set to Frequency List, the coded ARFCNs for
frequency hopping will be delivered in the form of frequency list.
Therefore, the assignment command will be delivered in one period, thus

shortening the call setup time.
5.2 Long Call Setup Time Due to Reporting of
Two Classmark Change Messages
After swapping for Huawei equipment at a site, the call setup time became
longer.
When Huawei CN is used, an additional Classmark Change message is
reported during the call setup procedure if ECSC is set to Yes. The reason is
that the classmark enquiry procedure is enabled by default in Huawei CN.
Figure 1.1 shows the difference in the signaling procedure before and after the
swapping.
Figure 1.1 Classmark enquiry procedure enabled after the swapping

To avoid the preceding problem, set ECSC to Yes and CM Update Optimize
Type to 2, or coordinate with the CN to disable classmark enquiry at the CN.
5.3 Long Call Setup Time Due to Calling and
Called MSs Under Different MSCs
After swapping of some BSC in country R, the drive test results indicated that
the call setup time was about 3,000 ms longer than that before the swapping.
The call setup time is one of the acceptance check items of the project. It
refers to the delay between sending of the Channel Request message and
reception of the Alerting message.
As indicated by the parameter check result, the parameters in the network are
inherited from the previous network. Therefore, the parameters related to the
call setup time remain unchanged.
As indicated by the call signaling on the TEMS, the duration of the ciphering
mode setting procedure after the swapping is the same as that before the
swapping.
Compared with the signaling messages before the swapping, the signaling
messages after the swapping include another two Progress messages, which
are present between the Assignment Complete message and the Connect
message. The description in the progress messages is "Call is not end-to-end
PLMN/ISDN, further call progress information may be available in-band." As
indicated by messages traced at the CN, after the swapping, though the called
number under the test is the same as that before the swapping, the test call is
an inter-MSC one. That is because the calling MS is controlled by Huawei
MSC whereas the called number remains under its original MSC.
During the drive test on site after the swapping, the called number was the
same as that before the swapping, but the fact that the calling MS and the
called number were under different MSCs was not noticed. Therefore, when
checking consistency between test conditions before and after swapping, pay
attention to such hidden changes.

5.4 Long Call Setup Time Due to Inconsistency in
Signaling Procedures
After swapping for Huawei equipment at a site, the call setup time became
longer.
The comparison between the call setup signaling procedures before swapping
and those after swapping should be performed. If the call setup after swapping
includes more procedures than that before swapping, remove them. Take the
GP swapping in Bengal as an example. Figure 1.1 shows the difference
between the signaling procedures before and after the swapping.
Figure 1.1 GPRS suspension procedure enabled after the swapping
As shown in Figure 1.1, the difference between the signaling procedures was
the presence of a GPRS suspension procedure in the test after the swapping.
The presence of this procedure is related to whether the MS in the test has
performed GPRS attach.
According to 3GPP TS 44.108, as shown in Figure 1.2, the MS sends a GPRS
Suspension Request message to suspend PS services, regardless of whether
the MS has any PS service in progress.

Figure 1.2 GPRS suspension procedure described in the protocol
For CS call setup time test, the GPRS suspension procedure should be
removed. To remove this procedure, change the related setting of the mobile.
The following are two examples:
 On a NOKIA N73 mobile, set Tools > Settings > Connection > Packet
data > Packet data conn > When needed.
 On a Sony Ericsson K790 mobile, set Settings > Connectivity > Data
communication > Preferred service > CS only.
The GPRS suspension procedure is always present in the test after swapping.
If this procedure is not or seldom present in the test before swapping, this
procedure can be removed to reduce the delay.

6 Information Feedback
The following information is required:
 Data configuration file in .dat format
 Log files and comparison data obtained from drive tests
 Settings on the MSC, such as pre-paging and late assignment

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