1-Omo112050 Bsc6000 Gsm v9r8c12 Cell Parameters Issue1.00

GSM Cell Parameters

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Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved.

Descriptions1. Cell Parameters Overview 2. Cell Parameters Introduction 3. Case Study


Page2

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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Descriptions1. 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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Cell Data Mapping in Different Statuses of MSPower on

Select Network (Network Identity Para. )

Access Network (Call Control Para.)

Cell Selection (Cell Selection Para.)

Dedicated Mode (Call Control Para.)

Cell Reselection Mode (Cell Reselection Para.)

Paging Mode (Idle Mode 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 codingrange 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 codingrange is decimal 00~999.



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Location Area CodeLAC

Definition: To locate the location of MS, the whole area covered byeach 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.



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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 foridentity of each cell in the world.

Format: CI is composed of 16 bits, The available range is 0~65535.



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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 twoneighbor cells with same BCCH.Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved. Page14

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 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 Noncompounding 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.



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BS_AG_BLKS_RES

Value Range: 0~7 (Non-Compounding CCCHs), 0~2 (1 combined CCCH)

Unit: BlockDefault 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 reservedin one multi-frame for access granted channels (AGCH).



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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.



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PAGING_GROUPAGCH AGCH PCH1

The PCH10 2 First AGCH AGCH . Paging 1 Non-Compounding CCCH PCH Nthe Nth paging channel . BS_AG_BLKS_RES=2 period BS_PA_MFRAMES= 8 Multi-frame period .(51 frames).

1

8 Multiframe form one period

AGCH AGCH AGCH AGCH PCH1

PCH56

8 9

The second AGCH AGCH Paging periodAGCH AGCH. . . .

PCH10. . . . PCH56 . . . .

10

16. . . .


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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.



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Definition of Location Update

Inform the system the LA (Location Area) where the MS is to be paged.

LA 1

LA 2


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Condition of Location Update

Periodical location update Moving into a new LA

LA 1 LA 2 LA 3


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Procedure of Location Update

MSC

BSC

MS

1 Hour

1 Hour

1 Hour

++ +

+

+


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Abnormal OccasionThe subscriber you dialed has been powered off

But I am always powered on

LA 1 LA 2 LA 3


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Reason1 of Abnormal Occasion

MSC

BSC

MS

1 Hour

1 Hour

1 Hour


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Reason2 of Abnormal Occasion

MSC

BSC

MS

1 Hour

1 Hour

1 Hour

Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved. Page29

Application of T3212LAC Ping-pong Reselect A T3212=4 B T3212=8

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.Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved. Page30

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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Application of Neighbor Cell Description

B A D C A

B C DActual Neighbor Cells

Theoretical Neighbor Cells


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Application of Neighbor Cell Description

BA

C

A


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Call Control Parameters

MS MAX RetransTX-integer RACH Min. Access Level

Common Access Control ClassSpecial Access Control Class MBR

NCC AllowedRLT SACCH Multi-Frames

ECSCEmergent 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 the interval between multiple channel requests sent by MS.



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Calculation of SSTX-integerNon-Combined CCCH Combined CCCH

3, 8, 14, 50 4, 9, 16 5, 10, 20 6, 11, 25 7, 12, 32

5576 109 163

4152 58 86

217

115


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RACH Min. Access Level

Value Range: -121~-47 Unit: dbm

Default Value: -115Description: 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 downlink disconnection in case of SACCH decoding failures.



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Application of Radio Link TimeoutPoor coverage

P A

QB

Impact of radio link timeout


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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.

Call Type Normal Call AMR FR AMR HR

ParameterRadio Link Timeout (SACCH period(480ms))

Default Value 52

AFR Radio Link Timeout (SACCH period(480ms))

64

AHR Radio Link Timeout (SACCH period(480ms))

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 ParametersPage43


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.

Call Type Normal Call AMR FR AMR HR

ParameterSACCH Multi-Frames (SACCH period(480ms))

Default Value 31

AFR SACCH Multi-Frames (SACCH period(480ms))

48

AHR SACCH Multi-Frames (SACCH period(480ms))

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 will report MRs of it to the network.



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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.



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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.



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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.



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Application of MBRGSM1800 A -92dBm B -82dBm

S H -84dBm GSM900 C -68dBm D -90dBm F -88dBm E -78dBm

G -96dBm


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ECSC

Value Range: Yes, No Default Value: No

Description: Early Classmark Sending Control. It indicates if an MSin 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.



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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 andtransfer 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 SCCP connection is established and beforeMS BSS MSC

receiving message "CM ServiceAccepted" there will be a class markClassmark EnquiryClassmark Request

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 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.



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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 SelectionSearch the BCCH which have been storedCan decode any frequency?Yes No

Normal cell selection

Can reside in any cell ?Yes

No

Try to reside in its neighbor cell?Yes

No

Come into idle mode


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Normal Cell SelectionSearch all frequency Rank according to receiving level Select the frequency with the highest Rx_level Select the next frequency with the higher Rx_level No Is it a BCCH carrier? Stay in a cell(RX-LEV is the strongest, C1>0 , cell priority is not prohibited) without considering the PLMN No Emergency call mode

YES

Decode SCH, read cell para. on BCCH

Right PLMN&C1>0& priority is Normal ? All frequency not satisfy Come into idle modeYES

YES

Right PLMN&C1>0& priority is Low ? No

No

All frequency not satisfyYES

Try the cell of other PLMN allowed in the SIM card No


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Cell Selection ParameterC1=RLA_C-RXLEV_ACCESS_MINMAX((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.



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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: No, Yes Default Value: No Description: Cell_Bar_Access, worked together with CBQ to set the priority status of the cell in idle mode for cell selection and reselection.



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CBQ

Value Range: No, YesDefault Value: No Description: Cell_Bar_Qualify. CBQ only affects the cell

selection, but is not related to cell reselection. It works with CBAto define the access priorities of cells.



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Application of CBA and CBQCBA NoYes No Yes

CBQ NoNo Yes Yes

Cell Selection Priority NormalForbidden Low Low

Cell Reselection Priority NormalForbidden Normal Normal


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Application of CBQ

A

B

The traffic of cell A and B is heavy. Set these two cells with CBA=Yes, CBQ=No.


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Application of CBA

A B

B is a micro cell. Set B to Normal and A to Low.


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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 least 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.Page67


Cell Reselection ParameterC2=C1+CRO-TO*H(PT-T) C2=C1-CRO When PT is not equal to 31 When PT is equal to 31

For neighbor cell:H(PT-T)=0, when PT-T

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1-Omo112050 Bsc6000 Gsm v9r8c12 Cell Parameters Issue1.00