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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 Parameters Overview
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 more and better services although basing on limited resources.
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Cell Parameters Overview Cell Parameters can 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 Code ( MCC ) 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 Code ( MNC ) 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 Code ( LAC ) 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 Identity ( CI ) 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 cell’s 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 Code ( NCC ) 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 Code ( BCC ) 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 Value : Yes 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 combine
d CCCH) 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
the number 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
whether paging 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
defines the 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 Hour
1 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. M
S 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
the interval 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, 50 55 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 sa
y, 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
downlink disconnection 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 BP Q
Poor coverage
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Radio Link Timeout To increase the robustness of the SACCH channel, to improve
the AMR 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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SACCH Multi-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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SACCH Multi-Frames To increase the robustness of the SACCH channel, to improve the AMR
network 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 mea
sured by MS. If a neighbor cell’s NCC is permitted, MS will report 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 i
n the cell is allowed to use early Classmark sending. Yes: The MS reports Classmark3 to the network immediately afte
r link setup. No: The MS is forbidden to report its Classmark3 to network initi
atively. Location: Cell Attributes/Call Control/Basic Call Control Parameter
s
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Definition of Classmark In GSM system, the abilities that MS supports, such as service ability, b
and 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:Classmark1 、 Classmark2 、 Classmark3.
Network knows about abilities of MS either via inquiring for MS’s 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 SCCP co
nnection 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 selectionCan 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 is Normal ?
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 conside
ring 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 r
equired 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
transmit power 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 select
ion, 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 CBQCell Selection
PriorityCell Reselection
Priority
0 0 Normal Normal
1 0 Forbidden Forbidden
0 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”.
BA
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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 longer than 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 lea
st the value of CRH for longer than 5 seconds, a location update process and the cell 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<0
H(PT-T)=1, when PT-T ≥ 0
For serving cell:
H(PT-T) = 0
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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 for changing the effect of CRO on C2)
Unit: Second
Default Value: 0
Description: Cell Reselect Penalty Time. It is used to ensure the safety and 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
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Signaling Flow of Immediate Assignment Optimization
MS BTS BSC MSC
Channel_req Channel_Required
Channel_Active
Channel_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
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Cell Direct Try Forbidden Threshold Value Range: 0~100(%)
Unit: None
Default Value: 50
Description: If the parameter Assignment 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 of Cell Direct Try
Forbidden Threshold during channel assignment.
Location: Cell Attributes/Other Attributes/Advanced/Other
Parameters
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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 Directed Retry Load Access
Threshold are selected as candidate target cells.
Location: Cell Attributes/Call Control/Basic Call Control
Parameters
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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
Page83Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
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
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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 out before 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
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Intra-BSC Handover Signaling FlowMS BTS1 BSC BTS2 MS MSC
Channel_Active
Channel_Active_Ack
Measure Report from MS
HANDOVER COMMAND
Handover AccessHandover_Detect
PHYINFO
PHYINFO
First SABM
Establish_IND
HANDOVER COMPLETE
Handover_Performed
UA
Page86Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
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 of BCCH 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
Page87Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
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
Page88Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
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 current cell by comparing the TA with the value of this parameter.
Location: Cell Attributes
Page89Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
Interference Band Threshold 0~5 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
Page90Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
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
Page91Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
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
Page92Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
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 the MSC, 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
Page93Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
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 the message 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, F
ACCH and SACCH. This is because these channels have different transmission rate. Location: Cell Attributes/Call Control/Advanced/Timer
Page94Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
Use LAPDm N200 Range: Yes, No Default Value : No Description: Determines whether BSC delivers LAPDm N200 pa
rameters 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
Page95Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
Power on
BA2 / RLT / MBRNCC Allowed / PWRC Emergent Call DisabledCall Re-establishment ForbiddenUL DTX / DL DTXSACCH Multi-FramesMax Resend Times of Phy. Info. / T3105 Max TAT200 and N200Use LAPDm N200TCH immediate assignmentImmediate assignment optimization Direct Retry Para.
MS MAX Retrans / ECSCTX-integer / RACH Min. Access LevelCommon/Special Access Control Class
CGI, BSIC
ATTT3212CCCH ConfBS_AG_BLKS_RESBS_PA_MFRAMESPaging Times
C2 (CRO,TO,PT,PI)CRHDSC
C1(RXLEV_ACCESS_MIN/MS TXPWR_MAX_CCH)CBA, CBQ
BA1InterferenceBand Threshold/Interference Calculation Period
Cell Data Mapping in Different Statuses of MS
Select 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.)
Page96Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
Descriptions
1. Cell Parameters Overview
2. Cell Parameters Introduction
3. Case Study
Page97Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
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
Page98Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
Case 2: Incorrect CGI Causes MS 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.
Page99Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
Case 3: RXLEV_ACCESS_MIN 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.
Page100Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
Case 4 : Too Small T3212 Causes 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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