1-Omo131010 Bsc6900 Gsm v9r11 Cell Parameters Issue1

8/2/2019 1-Omo131010 Bsc6900 Gsm v9r11 Cell Parameters Issue1

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GSM Cell Parameters


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Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved. Page2

Descriptions

1. Cell Parameters Overview

2. Cell Parameters Introduction


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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 moreand better services although basing on limited resources.


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Descriptions

1. Cell Parameters Overview

2. Cell Parameters Introduction


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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 MS

Power on

Select Network(Network Identity Para. )

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.)

Access Network(Call Control Para.)


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Network Identity Parameter CGICGI=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 iscurrently located.


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Location Area Code LACDefinition: 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. LAC adopts decimal coding. The

available range is from 0 to 65535. (please refer to specification

GSM0303, 0408, and 1111). One location area can contain one or

more cells.

Command: ADD GCELL / MOD GCELL / LST GCELL


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Cell Identity CIDefinition: 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 decimal numbers, 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 neardistance, their BSIC must be different so that MS can identify two

neighbor cells with same BCCH.


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Network Color Code NCCDefinition: NCC is a part of BSIC. MS uses it to distinguish

adjacent BTS that belong to different GSM PLMN.

Format: NCC is composed of decimal numbers, The available

range is 0 to 7.Command: ADD GCELL / MOD GCELL / LST GCELL


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BTS Color Code BCCDefinition: BCC is a part of BSIC. For its function, please refer

to above sections.

Format: BCC is composed of decimal numbers. The available

range is 0~7.Command: ADD GCELL / MOD GCELL / LST GCELL


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Idle Mode ParametersATT

CCCH Conf

BS_AG_BLKS_RES

BS_PA_MFRAMES

Period of Periodic Location Update(T3212)

Neighbor Cell Description (BA Table)


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ATTValue Range: Yes, No

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.

Command: SET GCELLIDLEBASIC / LIST GCELLIDLEBASIC


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CCCH ConfValue Range: 0 , 1 , 2 , 3 , 4 .

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.

Command: LST GCELLIDLEBASIC


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

CCCH)

Unit: Block

Description: It is also called Access Granted Blocks Reserved. It isthe number of CCCH channel message blocks that are reserved

in one multi-frame for access granted channels (AGCH).

Command: SET GCELLIDLEBASIC / LST GCELLIDLEBASIC


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BS_PA_MFRAMESValue Range: 2~9

Unit: Multi-frame period (51 frames)

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_GROUP

PCH10....

PCH10

1

2

9

10

TheFirst

Pagingperiod

8

AGCH AGCH

PCH56

16 PCH56

AGCH AGCH

AGCH AGCH

AGCH AGCH

AGCH AGCH

AGCH AGCH

BS_PA_MFRAMES= 8 Multi-frame period (51 frames)

.

.

.

.

.

.

.

.

BS_AG_BLKS_RES=2

8 Multi-

frame

form

one

period

PCH Nthe Nth paging channel

PCH1

PCH1

1 Non-Compounding CCCH

.

.

.

.

.

.

.

.

ThesecondPaging

period


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Period of Periodic Location Update(T3212)

Value Range: 0~255

Unit: 6 minutes

Description: It is the Periodic Location Update Timer. It defines

the interval of periodic location update.



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LA 1

LA 2

Definition of Location UpdateInform the system the LA (Location Area) where the MS is to be paged.


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LA 2

LA 3

Condition of Location UpdatePeriodical 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

++ ++ +

Reset Reset Reset


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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.

Command: SET GCELL2GBA1 / LST GCELL2GBA1

Table BA2 describes BCCH frequencies of the adjacent cells to

be measured when the MS is in dedicated mode.

Command: SET GCELLHO2GBA2 / LST GCELLHO2GBA2


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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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Refer to notes


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TX-integerValue Range: 3~12, 14, 16, 20, 25, 32, 50

Unit: RACH Timeslot (equals to a TDMA frame, 4.615ms)

Description: Used to calculate the number of timeslots in the

interval between multiple channel requests sent by MS.Command: SET GCELLIDLEBASIC / LST GCELLIDLEBASIC


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CS RACH Min. Access LevelValue Range: -121~-109

Unit: dbm

Description: The parameter affects the access of an MS in the CS

domain. 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.Command: SET GCELLCCACCESS / LST GCELLCCACCESS


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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 TimeoutTo 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-FramesValue Range: 0~63Unit: SACCH period (480ms)

Description: It is a timer used to determine whether the uplink radio linkconnection fails. BSS judges the uplink radio link failure according touplink 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.Command: SET GCELLCCACCESS / LST GCELLCCACCESS


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SACCH Multi-FramesTo 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: SELECTION0~7_ PERM.

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.Command: SET GCELLIDLEBASIC / LST GCELLIDLEBASIC


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Common Access Control Class

Value Range: L0_FORBID ~ L9_FORBID ( Level 0~9 Forbidden)

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.selected stands for forbidden

Command: SET GCELLCCBASIC / LST GCELLCCBASIC


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Special Access Control Class

Value Range: L11_FORBID~L15_FORBID

Description: It is used for load control, permitting or forbidding the

network access of some special level users. selected stands for

forbiddenCommand: SET GCELLCCBASIC / LST GCELLCCBASIC


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Multi-Band Report (MBR)Value Range: 0~3

Description: Multi-Band Report. It is used to inform MS to report the

adjacent cells in a controllable way.



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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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ECSCValue Range: Yes, 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 immediatelyafter link setup.

No: The MS is forbidden to report its Classmark3 to network

initiatively.



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Definition of ClassmarkIn 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:Classmark1 Classmark2 Classmark3.

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 FlowFor dual-band MS, after the SCCP

connection 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 DisableValue 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 isprohibited.



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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 whichhave been stored

Normal cell selectionCan decodeany frequency?

Come intoidle mode

Yes

No

Can reside inany cell ?

No Try to reside in itsneighbor cell?

Yes

No

Yes


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Normal Cell SelectionSearch allfrequency

Rank according toreceiving level

Come into

idle mode

Is it a BCCH carrier?

Right PLMN&C1>0&priority is Normal ?

Select the next frequencywith the higher Rx_level

YES No

YES

Try the cell of other PLMNallowed 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 callmode

Select the frequency withthe highest Rx_level

Decode SCH, readcell 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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MS_TXPWR_MAX_CCHValue Range: 0~19 (900M), 0~31(1800M)

Unit: level

Description: This parameter determines the maximum transmit

power level of the MS when it begins to access a cell and hasnot yet received power control command.

Command: SET GCELLCCCH / LST GCELLCCCH


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CBAValue Range: No, Yes

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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Application of CBA and CBQ

CBA CBQ Cell Selection Priority Cell ReselectionPriority

No No Normal Normal

Yes No Forbidden ForbiddenNo Yes Low Normal

Yes Yes Low Normal


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Application of CBQ

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

A B


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Cell Reselection ProcessCell 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 tunesto 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 leastthe 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 15seconds. 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 0continuously 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 neighbor cell:

H(PT-T)=0, when PT-T


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CROValue Range: 0~63( the corresponding level value: 0~126dB,stepped every 2dB).

Unit: 2dB

Description: Cell Reselect Offset. It is a parameter in C2

calculation to give an intentional modification in MS cell

reselection.



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TOValue Range: 0~7 (the corresponding value is 0~60dB, 7

corresponds to Infinite).

Description: Cell Reselect Temporary Offset. It is a parameter in

C2 criterion to give a temporary modification within PT time.

Command: SET GCELLIDLEAD / LST GCELLIDLEAD


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PT

Value Range: 0~30(the corresponding time is 20~620s), 31(reserved forchanging the effect of CRO on C2)

Unit: Second

Description: Cell Reselect Penalty Time. It is used to ensure the safety

and validity of cell reselection because it helps to avoid frequent cellreselection.

Command: SET GCELLIDLEAD / LST GCELLIDLEAD


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CRHValue Range: 0~14, the step size is 2dB

Unit: dB

Description: Cell Reselection Hysteresis. It is the parameter used

when cell reselection happens between two location areas.Command: SET GCELLIDLEBASIC / LST GCELLIDLEBASIC


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QuestionOne MS is switched on. The parameters of the MS and cells shown on the

next slide.

Other given condition:

Rx_Lev_Access_Min = 8 (-102 dBm)

MS_TXPWR_MAX_CCH=5 (for every cell)Please give the answers for following questions:

Which cells will be selected after the MS is powered on ?

Which cell will be selected after cell reselect (suppose the current serving cell is H)?

Cell Selecteselct Answe


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Question1800MHZRXLev= -66dBmCBA=No, CBQ=NoPI=YesPT=1CRO=6MCC=460CRH=6dBTO=6MNC=01

900MHZRXLev= -58dBmCBA=No, CBQ=NoPI=Yes

PT=0CRO=5MCC=460CRH=4dBTO=7MNC=99

B

CH 900MHZRXLev= -65dBm

CBA=No, CBQ=NoPI=NoPT=0

CRO=2MCC=460CRH=12dBTO=6MNC=011800MHZ

RXLev= -78dBmCBA=No, CBQ=NoPI=YesPT=0CRO=4MCC=460CRH=4dBTO=6

MNC=01

G

F900MHZRXLev= -62dBmCBA=Yes, CBQ=YesPI=YesPT=0CRO=3MCC=460CRH=6dBTO=6MNC=01

E

900MHZRXLev= -64dBmCBA=Yes, CBQ=YesPI=NoPT=1CRO=0MCC=460CRH=6dBTO=6MNC=01

D

1800MHZRXLev= -75dBmCBA=No, CBQ=NoPI=YesPT=1CRO=10MCC=460CRH=0dBTO=6MNC=01

Dual Band

IMSI 460010000032093

MSA

900MHZ

RXLev= -59dBmCBA=No, CBQ=YesPI=YesPT=0CRO=10MCC=460CRH=6dBTO=7MNC=01


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Other ParametersCall Reestablishment Forbidden

TCH Immediate Assignment

Immediate Assignment Optimization

Direct Retry

Assignment Cell Load Judge EnableCell 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 PeriodFR/HR UL DTX

FR/HR USE DL DTX

T200 and N200

Use LAPDm N200


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Call Reestablishment ForbiddenValue Range: Yes, No

Description: Informing MS whether call reestablishment is

allowed or not.

Command: SET GCELLBASICPARA / LSTGCELLBASICPARA


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TCH Immediate Assignment

Value Range: Yes, 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.

Command: SET GCELLBASICPARA / LST GCELLBASICPARA


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Immediate Assignment Optimization

Value Range: 0, 1

Description: This parameter is mainly used for satellite transmission,

i.e., to reduce the impact of satellite transmission delay.

1: when the Transmission Mode of the BTS is Satellite transmission

0: when the Transmission Mode of the BTS is Terrestrial transmission

Command: LST GCELLBASICPARA


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Signaling Flow of ImmediateAssignment 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

MS BTS BSC

IMM_ASS_CMD

CHAN_ACT_ACK


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Direct RetryValue Range: Yes, No

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.



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Assignment Cell Load Judge Enable

Value Range: Enable, 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.



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Cell Direct Try Forbidden Threshold

Value Range: 0~100(%)

Unit: percent

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.

Command: SET GCELLOTHEXT / LST GCELLOTHEXT


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Directed Retry Load Access Threshold

Value Range: 0~100(%)

Unit: percent

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.



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Max Resend Times of Phy. Info.Range Value : 1~255

Unit: T imes

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.

Command: SET GCELLHOAD / LST GCELLHOAD


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T3105Range Value : 0~255

Unit: 10ms

Description: When BTS sends physical information to the MS,the BTS starts the timer T3105. If the timer T3105 times out

before receive the SABM frame from MS, BTS re-sends physicalinformation to MS and restarts the timer T3105.

Command: SET GCELLHOAD / LST GCELLHOAD


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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

PHYINFOPHYINFO

First SABM

Establish_IND

HANDOVER COMPLETEHandover_Performed

UA


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PWRCValue range: Yes, No.

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.

Command: SET GCELLCCCH / LST GCELLCCCH


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Cell Extension TypeValue Range: Normal cell, Double TS Ext cell

Description: It indicates whether a cell is an extended cell and

the extended cell mode.



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Max TAValue Range:

0~63 (Normal cell)

0~255 (Double TS Ext cell)

Unit: Bit period (1 bit = 0.55km)

Description: Maximum Time Advance. It determines the actual coveragearea of BTS. When BTS receives the channel request message, itdetermines whether channel assignment should take place in the currentcell by comparing the TA with the value of this parameter.


I f B d Th h ld 0 5


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Interference Band Threshold 0~5Value Range: 48~115

Unit: -dBmRecommended Values

110 ( Interference band threshold 0)


98 ( Interference band threshold 2 )




Description: It decides the corresponding value for each interferenceband (from band 1 to band 5) and used to measure the uplinkinterference during the SDCCH/TCH(F)/TCH(H) timeslot is in idle mode.



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Interference Calculation PeriodValue range: 1~31

Unit: SACCH period (480 ms)

Recommended Values: 20

Description: Before the BTS transmits the radio resource indicationmessage to the BSC, the interference levels measured on idle channels inthe period defined by this parameter are averaged. The averageinterference level is used to classify the interference levels on idle channelsinto five interference bands. A too big value of this parameter cannot reflectthe change of interference. A too small value of this parameter wastes theresources.



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FR/HR UL DTXValue Range: May use, Shall use, Shall not use

Description: It is used to indicate whether MS uses FR/HR DTX

function. It shows the DTX state of the MS in the previous

measurement period.



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FR/HR Use DL DTXValue range: Yes, No

Default Value: Yes

Description: This parameter indicates whether downlink DTX is used

in a cell . The use of FR/HR 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.



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T200 and N200T200 :

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 isrequested to acknowledge the reception. If this message is lost for unknownreasons, 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 thetimer 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.

Command: SET GCELLCCTMR / LST GCELLCCTMR


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Use LAPDm N200Range: Yes, 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.

Command: SET GCELLCCTMR / LST GCELLCCTMR


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1-Omo131010 Bsc6900 Gsm v9r11 Cell Parameters Issue1