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Copyright 2008 Huawei Technologies Co., Ltd. All rights reserved.
GSM Cell Parameters
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Descriptions
1. Cell Parameters Overview
2. Cell Parameters Introduction
3. Case Study
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Cell ParametersOverview
Cell Parameters include the most of radio network
parameters transmitted via Um interface.
Via receiving cell parameters, MS is able to exactly select,
access and coordinate with the network through which
different kinds of service is provided.
Via reasonably cell parameters, BTS can run in high point
and whole system can be effectively utilized to provide moreand better services although basing on limited resources.
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Cell ParametersOverview
Cell Parameterscan be sent through two kinds of logical channels
BCCH (in idle mode)
SACCH (in dedicated mode)
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Descriptions
1. Cell Parameters Overview
2. Cell Parameters Introduction
3. Case Study
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Introduction to Cell Parameters
Huawei GSM cell parameters:
Network Identity Parameters
Idle Mode Parameters
Call Control Parameters
Cell Selection and Reselection Parameters
Other Parameters
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Power on
Access Network
(Call Control Para.)
Select Network
(Network Identity Para. )
Cell Data Mapping in Different Statuses of MS
Cell Selection
(Cell Selection Para.)
Paging Mode
(Idle Mode Para.)
Dedicated Mode
(Call Control Para.)
Cell Reselection Mode
(Cell Reselection Para.)Idle Mode
(Idle Mode Para.)
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Network Identity Parameter CGI
Network identity parameters mainly include
Cell Global Identity (CGI)
Base Station Identity Code (BSIC)
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Network Identity Parameter CGI
CGI=MCC+MNC+LAC+CI
Once MS receives SYS INFO, it decodes the CGI information, and
decides whether it can stay in the cell according to the MCC and
MNC indicated by CGI.
At the same time, it judges whether the current location area is
changed, so as to decide whether to execute location update.
During the location update process, MS will report the new LAI to
the network, so that the network can know the LA in which MS is
currently located.
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Mobile Country CodeMCC
Definition: MCC consists of 3 decimal numbers. It indicates the
home country of the mobile subscriber.
Format: MCC is composed of 3 decimal numbers. The coding
range is decimal 000~999.
Location: Cell Attributes
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Mobile Network CodeMNC
Definition: MNC is used to uniquely identify a specific GSM PLMN
network in a certain country (decided by MCC).
Format: MNC is composed of two decimal numbers. The coding
range is decimal 00~999.
Location: Cell Attributes
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Location Area CodeLAC Definition: To locate the location of MS, the whole area covered by
each GSM PLMN is divided into different location areas. LAC is used
to identify different location areas.
Format: LAI contains LAC, which is composed of two bytes. LAC
adopts hexadecimal coding. The available range is from 0001H to
FFFEH. The code 0000H and FFFFH cannot be used (please refer
to specification GSM0303, 0408, and 1111). One location area can
contain one or more cells.
Location: Cell Attributes
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Cell IdentityCI
Definition: To uniquely identify each cell in the GSM PLMN, the
network operator needs to allocate one code for each cell, which is
the cell identity (CI). Cell identity, together with LAI, is used for
identity of each cell in the world.
Format: CI is composed of 16 bits, The available range is 0~65535.
Location: Cell Attributes
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Network Identity Parameter BSIC
BSIC=NCC+BCC
In GSM system, each BTS is allocated with a color code, which is
called BSIC. MS can identify two cells with the same BCCH by the
help of BSIC.
In network planning, make sure that BCCH of neighbor cells are
different from the serving cells BCCH to reduce the interference.
Practically it is still possible that a same BCCH is re-used in the
surrounding cells. For cells using the same BCCH in a relevant near
distance, their BSIC must be different so that MS can identify two
neighbor cells with same BCCH.
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Network Color CodeNCC
Definition: NCC is a part of BSIC. MS uses it to distinguish
adjacent BTS that belong to different GSM PLMN.
Format: NCC is composed of 3 bits, with the range of 0 to 7.
Location: Cell Attributes
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BTS Color CodeBCC
Definition: BCC is a part of BSIC. For its function, please refer
to above sections.
Format: BCC is composed of 3 bits. The available range is 0~7.
Location: Cell Attributes
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Idle Mode Parameters
ATT
CCCH Conf
BS_AG_BLKS_RES
BS_PA_MFRAMES
Paging Times
Period of Periodic Location Update(T3212)
Neighbor Cell Description (BA Table)
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ATT
Value Range: Yes, No
Default ValueYes
Description: It is Attach-detach allowed. It is used to inform MS
whether IMSI attach-detach is allowed in this cell. If it is set to
Yes, the network will not process the connection to the called
mobile subscriber when MS is power-off. Thus network processing
time and radio resources are saved. Otherwise the network will
process the connection even though the MS has been powered off. Location: Cell Attributes/Idle Mode/Basic Idle Parameters
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CCCH Conf
Value Range: 1 Compounding CCCH , 1 Non-Compounding CCCH,
2 Non-Compounding CCCHs, 3 Non-compounding CCCHs, 4 Non-
compounding CCCHs.
Default Value: When there is one TRX in the cell, one combined CCCH
is recommended (in a system with few paging messages in location
area). For others, it is configured according to the number of TRX in
the cell.
Description: It is Common Control Channel Configuration. CCCH
configuration determines the capacity of PCH, AGCH and RACH. This
parameter can be automatically configured by system according to the
TRX channel configuration.
Location: Cell Attributes/Idle Mode/Basic Idle Parameters
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BS_AG_BLKS_RES
Value Range: 0~7 (Non-Compounding CCCHs), 0~2 (1 combinedCCCH)
Unit: Block
Default Value: 2 (Non-combined CCCH), 1(1 combined CCCH)
Description: It is also called Access Granted Blocks Reserved. It is
the number of CCCH channel message blocks that are reserved
in one multi-frame for access granted channels (AGCH).
Location: Cell Attributes/Idle Mode/Basic Idle Parameters
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BS_PA_MFRAMES
Value Range: 2~9
Unit: Multi-frame period (51 frames)
Default Value: 2 Multi-frame period
Description: It is Paging Channel Multi-frames. It defines thenumber of multi-frames used as a cycle of paging sub-channels.
Location: Cell Attributes/Idle Mode/Basic Idle Parameters
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Paging Times
Value Range:1~8
Unit: Times
Default Value: 4
Description: This parameter is used for BTS to determine whetherpaging is resent. Together with the paging times configured in MSC,
they jointly control the paging resend times. The total paging times
are approximate to be the multiplication of the two.
Location: Cell Attributes/Call Control/Basic Call Control Parameters
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Period of Periodic Location Update(T3212)
Value Range: 0~255
Unit: 6 minutes
Default Value: 20
Description: It is the Periodic Location Update Timer. It definesthe interval of periodic location update.
Location: Cell Attributes/Idle Mode/Basic Idle Parameters
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LA 1
LA 2
Definition of Location Update
Inform the system the LA (Location Area) where the MS is to be paged.
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LA 2
LA 3
Condition of Location Update
Periodical location update
Moving into a new LA
LA 1
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Procedure of Location Update
BSC
MSC
MS
1 Hour 1 Hour 1 Hour
++ ++ +
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Abnormal Occasion
LA 3
LA 2
LA 1
But I am always
powered on
The subscriber
you dialed has
been powered off
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Reason1 of Abnormal Occasion
BSC
MSC
MS
1 Hour 1 Hour1 Hour
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Reason2 of Abnormal Occasion
BSC
MSC
MS
1 Hour 1 Hour 1 Hour
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Application of T3212
Even if T3212 setting is less than the system (MSC) query time, the system
will still sometimes voice The subscriber you dialed is powered off.
A B
T3212=4 T3212=8
LAC
Ping-pong Reselect
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Neighbor Cell Description
There are table BA1 and table BA2.
Table BA1 describes BCCH frequencies of the adjacent cells to
be measured when the MS is in idle mode.
Location: Cell Attributes/Idle Mode/Advanced
Table BA2 describes BCCH frequencies of the adjacent cells to
be measured when the MS is in dedicated mode.
Location: Cell Attributes/Handover data/Advanced
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Theoretical Neighbor Cells Actual Neighbor Cells
B
CA
D
B
CA
D
Application of Neighbor Cell Description
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B
C
A
A
Application of Neighbor Cell Description
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Call Control Parameters
MS MAX Retrans
TX-integer
RACH Min. Access Level
NCC Allowed
RLT
SACCH Multi-Frames
Common Access Control Class
Special Access Control Class
MBR
ECSC
Emergent Call Disable
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MS MAX Retrans
Value Range: 1, 2, 4, 7 Unit: Time(s)
Default Value: 4 Times
Description: It is one of the random access control parameters. MS
MAX Retrans is the upper limit of times that MS is allowed to send
Channel Request in one immediate assignment procedure.
Location: Cell Attributes/Call Control/Basic Call Control Parameters
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TX-integer
Value Range: 3~12, 14, 16, 20, 25, 32, 50
Unit: RACH Timeslot (equals to a TDMA frame, 4.615ms)
Default Value: 32
Description: Used to calculate the number of timeslots in theinterval between multiple channel requests sent by MS.
Location: Cell Attributes/Idle Mode/Basic Idle Parameters
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Calculation of S
STX-integer
Non-Combined CCCH Combined CCCH
3, 8, 14, 5055 41
4, 9, 16 76 52
5, 10, 20 109 58
6, 11, 25 163 86
7, 12, 32 217 115
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RACH Min. Access Level
Value Range: -121~-47 Unit: dbm
Default Value: -115
Description: The parameter affects the access of an MS. That is to say,
the BTS determines the threshold of the level for the random access of
the MS. When the receive level of the RACH burst is lower than the
threshold, the BTS regards this access as an invalid access and no
decoding is performed. Only when the receive level for the burst
timeslot of the random access is greater than the threshold, the BTS
regards that this timeslot has an access request. Location: Cell Attributes/Call Control/Advanced/Access Control
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Radio Link Timeout
Value Range: 4~64, the step size is 4
Unit: SACCH period (480ms)
Default Value: 52
Description: This parameter is used for MS to decide downlinkdisconnection in case of SACCH decoding failures.
Location: Cell Attributes/Call Control/Basic Call Control Parameters
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Application of Radio Link Timeout
Impact of radio link timeout
A B
P Q
Poor coverage
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Radio Link Timeout
To increase the robustness of the SACCH channel, to improve theAMR network coverage performance, and to lower the call drop rate, in
practice the AMR FR/HR RLT should be set higher.
Normal Call Radio Link Timeout (SACCH period(480ms))
AMR FR AFR Radio Link Timeout (SACCH period(480ms))
AMR HR AHR Radio Link Timeout (SACCH period(480ms))
Default Value
52
Call Type Parameter
64
52
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SACCHMulti-Frames Value Range: 0~63
Unit: SACCH period (480ms)
Default Value: 31
Description: It is a timer used to determine whether the uplink radio link
connection fails. BSS judges the uplink radio link failure according to
uplink SACCH BER.
Every time BTS fails to decode the MR sent from MS, this timer decreases by 1;
Every time BTS succeeds to decode the MR, this timer increases by 2.
When this timer reaches 0, BTS judges that the uplink radio connection fails,
then BTS sends a radio connection failure message to BSC.
This parameter and the radio link timeout (RLT) are used to judge the
uplink/downlink radio connection failure.
Location: Cell Attributes/Call Control/Basic Call Control Parameters
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SACCHMulti-Frames
To increase the robustness of the SACCH channel, to improve the AMRnetwork coverage performance, and to lower the call drop rate, in practice
the AMR FR/HR SACCH Multi-Frames should be set higher.
Normal Call SACCH Multi-Frames (SACCH period(480ms))
AMR FR AFR SACCH Multi-Frames (SACCH period(480ms))
AMR HR AHR SACCH Multi-Frames (SACCH period(480ms))
Default Value
31
Call Type Parameter
48
32
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NCC Permitted
Value Range: Selection of 0~7 Perm.
Default Value: 11111111
Description: Network Color Code. It lists NCC that need be
measured by MS. If a neighbor cells NCC is permitted, MS willreport MRs of it to the network.
Location: Cell Attributes/Idle Mode/Basic Idle Parameters
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Common Access Control Class
Value Range: Level 0~9 Forbidden
Default Value: 0000000000
Description: One of the parameters of random access control
information. It is used for load control of ordinary subscribers, to
permit or forbid the network access of some common level users. 1
stands for forbidden and 0 for permitted.
Location: Cell Attributes/Call Control/Basic Call Control Parameters
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Special Access Control Class
Value Range: Level 10~14 Forbidden
Default Value: 00000
Description: It is used for load control, permitting or forbidding the
network access of some special level users. 1 stands for forbidden
and 0 for permitted.
Location: Cell Attributes/Call Control/Basic Call Control Parameters
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MBR
Value Range: 0~3
Default Value: 0
Description: Multi-Band Reporting. It is used to inform MS to report
the adjacent cells in a controllable way.
Location: Cell Attributes/Call Control/Basic Call Control Parameters
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Application of MBR
-92dBm -82dBmA B
C -68dBm
D -90dBm
E -78dBm
F -88dBm
G -96dBm
H -84dBm
GSM1800
GSM900
S
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ECSC
Value Range: Yes, No
Default Value: No
Description: Early Classmark Sending Control. It indicates if an MS
in the cell is allowed to use early Classmark sending.
Yes: The MS reports Classmark3 to the network immediately
after link setup.
No: The MS is forbidden to report its Classmark3 to network
initiatively.
Location: Cell Attributes/Call Control/Basic Call Control Parameters
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Definition of Classmark In GSM system, the abilities that MS supports, such as service ability,
band ability, power ability, encryption ability, is described by the classmark.
BSC decodes the information according to the requirement of network and
transfer to the network.
There are 3 kinds of classmark:Classmark1Classmark2Classmark3.
Network knows about abilities of MS either via inquiring for MSs
CLASSMARK or via requiring MS to report CLASSMARK3 immediately by
itself after link setup.
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Classmark Update Flow
For dual-band MS, after the SCCPconnection is established and before
receiving message "CM Service
Accepted" there will be a class mark
update flow.
CR message reports the information of
Classmrk 2. And in the class mark
update flow, MS will report Classmark
3 information which is related to the
dual-band capability.
Classmark Change
Classmark Enquiry
MS BSS MSC
Classmark Request
Classmark Update
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Information about Classmark 2/3
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Emergent Call Disable
Value Range: Yes, No
Default Value: No
Description: Emergence Call Disable. When EC Disable is set to
No, it means emergency call is permitted. Otherwise it is
prohibited.
Location: Cell Attributes/Call Control/Basic Call Control Parameters
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Cell Selection/Reselection Parameters
RXLEV_ACCESS_MIN MS_TXPWR_MAX_CCH
CBQ (Cell_Bar_Qualify)
CBA (Cell_Bar_Access)
CRO (Cell Reselection Offset)
TO (Temporary Offset)
PT (Penalty Time)
PI (Cell Reselect Parameters Indication)
CRH ( Cell Reselection Hysteresis)
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Cell Selection Process
There are two kinds of cell selection
Stored list cell selection
Normal cell selection
In fact, the process might be different for different MSs
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Stored List Cell Selection
Search the BCCH which
have been stored
Normal cell selection
Can decode
any frequency?
Come into
idle mode
Yes
No
Can reside in
any cell ?
No Try to reside in its
neighbor cell?
Yes
No
Yes
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Normal Cell SelectionSearch all
frequency
Rank according to
receiving level
Come into
idle mode
Is it a BCCH carrier?
Right PLMN&C1>0&
priority isNormal ?
Select the next frequency
with the higher Rx_level
YES No
YES
Try the cell of other PLMN
allowed in the SIM card
Stay in a cell(RX-LEV is strongest, C1>0 ,
cell priority is not prohibited) without
considering the PLMN
All frequency not satisfy
No
YES
Emergency call
mode
Select the frequency with
the highest Rx_level
Decode SCH, read
cell para. on BCCH
No
All frequency not satisfy
No
No YES
Right PLMN&C1>0&
priority is Low ?
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Cell Selection Parameter
C1=RLA_C-RXLEV_ACCESS_MIN-
MAX((MS_TXPWR_MAX_CCH - P), 0)
RLA_C: Receiving level of MS
RXLEV_ACCESS_MIN: Minimum receiving level of MS permitted to access
MS_TXPWR_MAX_CCH: Maximum transmit power level of MSs
P: Maximum Physical supported transmitting power of MS.
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RXLEV_ACCESS_MIN
Value Range: 0~63 (-110 dBm ~ -47 dBm)
Default Value: 8
Description: It means the minimum receive signal level
required for MS to access a cell.
Location: Cell Attributes
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MS_TXPWR_MAX_CCH
Value Range: 0~19
Unit: level
Default Value: 5 (900MHz cell),0 (1800/1900MHz cell)
Description: This parameter determines the maximum transmitpower level of the MS when it begins to access a cell and has
not yet received power control command.
Location: Cell Attributes/Other Attributes/Advanced/Public
Channel Control
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CBA
Value Range: 0, 1
Default Value: 0
Description: Cell_Bar_Access, worked together with CBQ to set
the priority status of the cell in idle mode for cell selection and
reselection.
Location: Cell Attributes/Idle Mode/Basic Idle Parameters
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CBQ
Value Range: 0 , 1
Default Value: 0
Description: Cell_Bar_Qualify. CBQ only affects the cell
selection, but is not related to cell reselection. It works with CBA
to define the access priorities of cells.
Location: Cell Attributes/Idle Mode/Basic Idle Parameters
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Application of CBA and CBQ
CBA CBQ Cell SelectionPriorityCell Reselection
Priority0 0 Normal Normal
1 0 Forbidden Forbidden0 1 Low Normal
1 1 Low Normal
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Application of CBQ
The traffic of cell A and B is heavy. Set these two cells with
CBA=1, CBQ=0.
A B
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Application of CBA
B is a micro cell. Set B to Normal and A to Low.
B
A
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Cell Reselection Process Cell reselection for cells in the same location area
If the C2 value of the target cell is higher than that of the serving cell for longerthan 5 seconds, a cell reselection process will be performed and the MS tunes
to the new cell.
Cell reselection for cells in different location areas
If the C2 value of the target cell is higher than that of the serving cell by at least
the value of CRH for longer than 5 seconds, a location update process and thecell reselection process will be performed.
Two consecutive cell reselections caused by C2 have a time interval of 15
seconds. In other words to say, if because of C2 a MS reselected to a cell,
then the MS cannot reselect to another cell by the cause of C2 within 15
seconds.
If current serving cell is prohibited, or down link fails, or C1 is less than 0
continuously for 5s, cell reselection will also be triggered.
MS starts a cell reselection if the access times exceed the MAX retrans.
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Cell Reselection Parameter
C2=C1+CRO-TO*H(PT-T) When PT is not equal to 31
C2=C1-CRO When PT is equal to 31
For neighbour cell:
H(PT-T)=0, when PT-T
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CRO Value Range: 0~63( the corresponding level value: 0~126dB,
stepped every 2dB).
Unit: 2dB
Default Value: 0
Description: Cell Reselect Offset. It is a parameter in C2
calculation to give an intentional modification in MS cell
reselection.
Location: Cell Attributes/Idle Mode/Basic Idle Parameters
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TO
Value Range: 0~7 (the corresponding value is 0~60dB, 7
corresponds to Infinite).
Default Value: 0
Description: Cell Reselect Temporary Offset. It is a parameter in
C2 criterion to give a temporary modification within PT time.
Location: Cell Attributes/Idle Mode/Advanced/Idle Parameter
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PT
Value Range: 0~31(the corresponding time is 20~620s), 31(reserved forchanging the effect of CRO on C2)
Unit: Second
Default Value: 0
Description: Cell Reselect Penalty Time. It is used to ensure the safetyand validity of cell reselection because it helps to avoid frequent cell
reselection.
Location: Cell Attributes/Idle Mode/Advanced/Idle Parameter
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PI
Value Range: Yes , No
Default Value: Yes
Description: Cell Reselect Parameters Indication, sent on the
broadcast channel of the cell. It is an indication to the existence
of Cell Reselect Offset(CRO), Temporary Offset(TO) and
Penalty Time(PT).
Location: Cell Attributes/Idle Mode/Basic Idle Parameters
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CRH
Value Range: 0~14, the step size is 2dB
Unit: dB
Default Value: 6
Description: Cell Reselection Hysteresis. It is the parameter used
when cell reselection happens between two location areas.
Location: Cell Attributes/Idle Mode/Basic Idle Parameters
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Other Parameters
Call Reestablishment Forbidden
TCH Immediate Assignment
Immediate Assignment Optimization
Direct Retry
Assignment Cell Load Judge Enable
Cell Direct Try Forbidden Threshold
Directed Retry Load Access Threshold
Min Power Level for Direct Try
Max Resend Times of Phy. Info. T3105
PWRC
Cell Extension Type
Max TA
Interference Band Threshold
Interference Calculation Period
UL DTX
DL DTX
T200 and N200
Use LAPDm N200
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Call Reestablishment Forbidden
Value Range: Yes, No
Default Value: Yes
Description: Informing MS whether call reestablishment is
allowed or not.
Location: Cell Attributes
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TCH Immediate Assignment
Value Range: Yes, No
Default Value : No
Description: Option "Yes" means that TCH channel can be
immediately assigned as signaling and traffic channel when
SDCCH has no available resource. The option "No" means that
only SDCCH can be assigned.
Location: Cell Attributes
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Immediate Assignment Optimization
Value Range: Yes, No
Default Value : No
Description: This parameter is mainly used for satellite transmission,
i.e., to reduce the impact of satellite transmission delay.
Yes: when the Transmission Mode of the BTS is Satellite transmission
No: when the Transmission Mode of the BTS is Terrestrial transmission
Location: Cell Attributes/Call Control/Advanced/Call Control
Signaling Flow of Immediate
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Signaling Flow of Immediate
Assignment Optimization
MS BTS BSC MSC
Channel_req Channel_Required
Channel_ActiveChannel_Active_Ack
IMMEDIATE ASSIGN COMMAND
Establish_IND (CM Service Req)
CR(Complete_L3_
information)
CM Service Accepted
CC
(NOTE 1)
First SABM
UA
CHAN_ACT
IMM_ASS_CMD
MS BTS BSC
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Direct Retry
Value Range: Yes, No
Default Value : Yes
Description: This parameter indicates the whether the directed
retry on the TCH is allowed. If this parameter is set to Yes, the
handover procedure is used and the MS is handed over to the
neighboring cell.
Location: Cell Attributes
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Assignment Cell Load Judge Enable
Value Range: Enable, Disable Default Value: Disable
Description: When the Assignment Cell Load Judge Enabled is set
to Yes, the direct try flow is allowed if the following two conditions
are met:
The cell supports the direct retry function.
The load of the cell is larger than or equal to the Cell Direct Try
Forbidden Threshold.
Location: Cell Attributes/Call Control/Basic Call Control Parameters
C
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Cell Direct Try Forbidden Threshold
Value Range: 0~100(%) Unit: None
Default Value: 50
Description: If the parameterAssignment Cell Load Judge
Enabled is set to Yes, the direct retry process is started and
channels are assigned when the cell supports direct retry and the
load of the current cell is equal to or greater than the value ofCell
Direct Try Forbidden Threshold during channel assignment.
Location: Cell Attributes/Other Attributes/Advanced/Other
Parameters
Di d R L d A Th h ld
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Directed Retry Load Access Threshold
Value Range: 0~100(%) Unit: None
Default Value : 85
Description: This parameter is used to adjust the candidate target
cells during direct retry.
When target cells are selected during direct retry, only the cells whose
loads are smaller than or equal to the DirectedRetryLoadAccess
Threshold are selected as candidate target cells.
Location: Cell Attributes/Call Control/Basic Call Control Parameters
Mi P L l f Di t T
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Min Power Level for Direct Try
Value Range: 0~63 (-110dBm~-47dBm)
Default Value :16
Description: This parameter indicates the selection of candidate cell
for direct try. If the receiving level of the cell exceeds the value of
this parameter, this cell can be selected as candidate target cells.
Location: Cell Attributes/ Handover Data/Advanced/HO Control
M R d Ti f Ph I f
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Max Resend Times of Phy. Info.
Range Value :1~255
Unit: Times
Default Value :30
Description: This parameter specifies the maximum times Ny1 for re-
sending physical information.
If the number of resending times exceeds Ny1 and BTS still has not
received any correct SAMB frame from MS, BTS will send BSC the
connection failure message and handover failure message.
After BSC receives the messages, it will release the newly assigned
dedicated channel and stop timer T3105.
Location: Cell Attributes/Handover Data/Advanced/Cell HO Data
T3105
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T3105
Range Value : 0~255
Unit: 10ms
Default Value : 7
Description: When BTS sends physical information to the MS,
the BTS starts the timer T3105. If the timer T3105 times outbefore receive the SAMB frame from MS, BTS re-sends physical
information to MS and restarts the timer T3105.
Location: Cell Attributes/Handover Data/Advanced/Cell HO Data
I t BSC H d Si li Fl
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Intra-BSC Handover Signaling Flow
MS BTS1 BSC BTS2 MS MSC
Channel_ActiveChannel_Active_Ack
Measure Report from MS
HANDOVER COMMANDHandover Access
Handover_DetectPHYINFO
PHYINFO
First SABM
Establish_IND
HANDOVER COMPLETE
Handover_Performed
UA
PWRC
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PWRC
Value range: Yes, No.
Default Value: Yes
Description: It is used to indicate MS whether to delete received level value
obtained from the timeslots ofBCCH when MS measures receiving level
during base band hopping mode. When it is set to No, it means the influence of receiving level on BCCH is in
consideration.
If it is set to Yes, process it in the way mentioned above.
Location: Cell Attributes/Other Attributes/Advanced/Public Channel Control
C ll E t i T
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Cell Extension Type
Value Range: Normal cell, Double TS Ext cell Default Value: Configure this parameter according to the
practical situation.
Description: It indicates whether a cell is an extended cell and
the extended cell mode.
Location: Cell Attributes
M TA
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Max TA Value Range:
0~63 (Normal cell)
0~255 (Double TS Ext cell)
Unit: Bit period (1 bit = 0.55km)
Default Value
62 for normal cell
219 for dual TS extended cell
Description: Maximum Time Advance. It determines the actual coverage
area of BTS. When BTS receives the channel request message, it
determines whether channel assignment should take place in the currentcell by comparing the TA with the value of this parameter.
Location: Cell Attributes
Interference Band Threshold 0~5
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Value Range: 110~85
Unit: -dBm
Default Values
110 ( Interference band threshold 0)
105 ( Interference band threshold 1)
98 ( Interference band threshold 2 )
92 ( Interference band threshold 3 )
87 ( Interference band threshold 4 )
85 ( Interference band threshold 5)
Description: It decides the corresponding value for each interference
band (from band 0 to band 5) and used to measure the uplink
interference during the SDCCH/TCH(F)/TCH(H) timeslot is in idle mode.
Location: Cell Attributes/Other Attributes/Advanced/Other Parameters
Interference Calculation Period
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Interference Calculation Period
Value range: 1~31
Unit: SACCH period (480 ms)
Default Values: 20
Description: Before the BTS transmits the radio resource indication
message to the BSC, the interference levels measured on idle channels in
the period defined by this parameter are averaged. The average
interference level is used to classify the interference levels on idle channels
into five interference bands. A too big value of this parameter cannot reflect
the change of interference. A too small value of this parameter wastes the
resources.
Location: Cell Attributes/Other Attributes/Advanced/Other Parameters
UL DTX
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UL DTX
Value Range: May use, Shall use, Shall not use Default Value: Shall use
Description: It is used to indicate whether MS uses DTX function. It
shows the DTX state of the MS in the previous measurement period.
Location: Cell Attributes
DL DTX
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DL DTX
Value range: Yes, No
Default Value: Yes
Description: This parameter indicates whether downlink DTX
is used in a cell. The use of downlink DTX is also controlled by
the DTX switch in the MSC. If downlink DTX is forbidden in theMSC, downlink DTX is not used regardless of the setting of
this parameter. If downlink DTX is allowed in the MSC, the
setting of this parameter can determine whether downlink DTX
is used in the cell.
Location: Cell Attributes
T200 and N200
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T200 and N200 T200 :
T200 timers are used to avoid deadlock during data transfer on the data link layer. On the LAPDm layer, every time a message is sent, the opposite end is
requested to acknowledge the reception. If this message is lost for unknown
reasons, it will occur that both ends keep waiting, leading to system deadlock.
Therefore, a timer should be started when the sender sends a message. If the
timer times out, the sender will regard that the receiver has not received themessage and will resend the message.
N200
The maximum resend times are determined by N200.
Different timer values should be set for different LAPDm channels such as
SDCCH, FACCH and SACCH. This is because these channels have differenttransmission rate.
Location: Cell Attributes/Call Control/Advanced/Timer
Use LAPDm N200
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Use LAPDm N200
Range: Yes, No
Default Value : No
Description: Determines whether BSC delivers LAPDm N200
parameters to BTS. If it configured as Yes, then LPADm N200
parameters will be delivered to BTS, otherwise not.
Location: Cell Attributes/Call Control/Advanced/Timer
Cell Data Mapping in Different Statuses of MS
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Power on
BA2 / RLT / MBR
NCC Allowed / PWRC
Emergent Call Disabled
Call Re-establishmentForbidden
UL DTX / DL DTX
SACCH Multi-Frames
Max Resend Times of
Phy. Info. / T3105
Max TA
T200 and N200
Use LAPDm N200TCH immediate
assignment
Immediate assignment
optimization
Direct Retry Para.
MS MAX Retrans/ ECSCTX-integer / RACH Min. Access Level
Common/Special Access Control Class
CGI, BSIC
ATT
T3212
CCCH Conf
BS_AG_BLKS_RES
BS_PA_MFRAMES
Paging Times
C2 (CRO,TO,PT,PI)
CRHDSC
C1(RXLEV_ACCESS_MIN/
MS TXPWR_MAX_CCH)
CBA, CBQ
BA1
Interference
Band Threshold/
Interference
Calculation
Period
pp gSelect Network
(Network Identity
Para. )
Cell Selection
(Cell Selection
Para.)
Access Network
(Call Control Para.)
Idle Mode
(Idle Mode Para.)
Paging Mode
(Idle Mode Para.)
Cell Reselection Mode
(Cell Reselection Para.)
Dedicated Mode
(Call Control Para.)
Descriptions
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Descriptions
1. Cell Parameters Overview
2. Cell Parameters Introduction
3. Case Study
Case 1: Island Effect
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Case 1: Island Effect Case Description
During the process of optimization in a certain area, it is found
out that the signal is poor in a certain section of suburban
highway. The signal strength measured is less than -95dBm.
Handling Procedure
Modify the data in BSC. Add neighbor relationship to Cell A
and B for each other. The coverage problem is thus solved.
C
BA-92
-80 -95
Case 2: Incorrect CGI Causes MS
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Unable to Register on the Network Case description
The subscriber complained that MS could not register to the network,
or it was difficult to register to the network between BTS A and B, or
no network mark was displayed on the MS, but MS indicated that the
signal was very good. Some subscribers also complained that MS
could make MTC could not make MOC.
Cause analysis
CGI of the cell was modified. So the network register flow was not normal.
Although the signal was very good, MS could not get registered in the
network.
Default Value and summary
CGI is a very important parameter and should be configured correctly,
thus to ensured that the CGI data in BSC and MSC are the same.
Case 3: RXLEV_ACCESS_MIN
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Causes Signal Fluctuation Case description
Subscribers complain that the signal fluctuates in a certain area. On-
site test shows that this phenomenon does exist. From the testing
mobile, we can see that there are a lot of cells signals in this area.
Some frequencies are the suburb BTS signals far away from this area.
The cell reselection of MS is rather frequent. Handling procedure
Modify parameter RXLEV_ACCESS_MIN of all cells in urban area
and make them consistent with each other. The problem of signal
fluctuation is solved.
Default Value and summary
In area with complicated coverage, the RXLEV_ACCESS_MIN of
each cell should be kept same.
Case 4Too Small T3212 Causes
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MS Lose Connection with Network
Case description
A local GSM network has more than 6000 subscribers. There are four
BTSs. The network has been working properly. But from sometime on,
some MS often lost connection with network suddenly. The complaint
from subscribers in urban area increased.
Handling procedure
Modify T3212 to 10, i.e. 60 minutes. Modify the corresponding time of
MSC to 180 minutes. Two days observation shows no subscriber
complaint and the problem is solved.
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