Omf810001 gsm cell parameters issue1 01

GS M Ce ll P a ra me te rs

www.huawei.com

Copyright Š 2009 Huawei Technologies Co., Ltd. All rights reserved.

De s criptions 1.

Cell Parameters Overview

2.

Cell Parameters Introduction

3.

Case Study

Copyright Š 2009 Huawei Technologies Co., Ltd. All rights reserved.

Page3

Ce ll P a ra me te rs Ove rvie w 

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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Page4

Ce ll P a ra me te rs Ove rvie w 

Cell Parameters can be sent through two kinds of logical channels 

BCCH (in idle mode)



SACCH (in dedicated mode)

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Page5

De s criptions 1.

Cell Parameters Overview

2.

Cell Parameters Introduction

3.

Case Study

Copyright Š 2009 Huawei Technologies Co., Ltd. All rights reserved.

Page6

Introduction to Ce ll P a ra me te rs 

Huawei GSM cell parameters: 

Network Identity Parameters



Idle Mode Parameters



Call Control Parameters



Cell Selection and Reselection Parameters



Other Parameters

Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.

Page7

Ce ll Da ta Ma pping in Diffe re nt S ta tus e s of MS Power on Select Network (Network Identity Para. )

Access Network (Call Control Para.)

Dedicated Mode (Call Control Para.)

Cell Selection (Cell Selection Para.)

Cell Reselection Mode (Cell Reselection Para.)

Paging Mode (Idle Mode Para.)

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Page8

Idle Mode (Idle Mode Para.)

Ne twork Ide ntity P a ra me te r — CGI 

Network identity parameters mainly include 

Cell Global Identity (CGI)



Base Station Identity Code (BSIC)

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Page9

Ne twork Ide ntity P a ra me te r — 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.

Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.

Page10

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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Page11

Mobile Ne twork 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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Page12

Loca tion Are a 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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Page13

Ce ll Ide ntity （ 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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Page14

Ne twork Ide ntity P a ra me te r — BS IC 

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. Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.

Page15

Ne twork 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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Page16

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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Page17

Idle Mode P a ra me te rs 

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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Page18

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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Page19

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.



Location: Cell Attributes/Idle Mode/Basic Idle Parameters

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Page20

BS _AG_BLKS _RES 

Value Range: 0~7 (Non-Compounding CCCHs), 0~2 (1 combined 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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Page21

BS _P A_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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Page22

P e riod of P e riodic Loca tion Upda te (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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Page23

De finition of Loca tion Upda te Inform the system the LA (Location Area) where the MS is to be



paged.

LA 1

LA 2

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Page24

Condition of Loca tion Upda te 

Periodical location update



Moving into a new LA

LA 1 LA 2 LA 3

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Page25

P roce dure of Loca tion Upda te

MSC

BSC

MS

1 Hour

1 Hour

≥

1 Hour

++ +

+

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+

Page26

Abnorma l Occa s ion The subscriber you dialed has been powered off But I am always powered on

LA 1 LA 2 LA 3

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Page27

Re a s on1 of Abnorma l Occa s ion

MSC

BSC

MS

1 Hour

1 Hour

1 Hour

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Page28

Re a s on2 of Abnorma l Occa s ion

MSC

BSC

MS

1 Hour

1 Hour

1 Hour

≤ Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.

Page29

Applica tion of T3212 LAC “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”.

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Page30

Ne ighbor Ce ll De s cription 

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. 



Lo c a t io n : Ce ll At t rib u t e s /Id le Mo d e /Ad v a n c e d

Table BA2 describes BCCH frequencies of the adjacent cells to be measured when the MS is in dedicated mode. 

Lo c a t io n : Ce ll At t rib u t e s /Ha n d o v e r d a t a /Ad v a n c e d

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Page31

Applica tion of Ne ighbor Ce ll De s cription

B

B C

A D

Theoretical Neighbor Cells

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A

C D

Actual Neighbor Cells

Page32

Applica tion of Ne ighbor Ce ll De s cription

B A

C

A

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Page33

Ca ll Control P a ra me te rs 

MS MAX Retrans



Common Access Control Class



TX-integer



Special Access Control Class



RACH Min. Access Level



MBR



NCC Allowed



ECSC



RLT



Emergent Call Disable



SACCH Multi-Frames

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Page34

MS MAX Re tra ns 

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

Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.

Page35

TX-inte ge r 

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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Page36

Ca lcula tion of S TX-integer

S 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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Page37

RACH Min. Acce s s Le ve l 

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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Page38

Ra dio Link Time out 

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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Page39

Applica tion of Ra dio Link Time out Poor coverage

P

Q B

A

Impact of radio link timeout

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Page40

Ra dio Link Time out 

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.

Call Type

Default Value

Parameter

Normal Call



Radio Link Timeout (SACCH period(480ms))

52

AMR FR



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

64



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

52

AMR HR

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Page41

S ACCH Multi-Fra me s 

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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Page42

S ACCH Multi-Fra me s 

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

Default Value

Parameter

Normal Call



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

31

AMR FR



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

48



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

32

AMR HR

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Page43

NCC P e rmitte d 

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 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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Page44

Common Acce s s Control Cla s s 

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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Page45

S pe cia l Acce s s Control Cla s s 

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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Page46

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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Page47

Applica tion of MBR GSM1800 A -92dBm

B -82dBm

S H -84dBm GSM900

C -68dBm

D -90dBm

E -78dBm F -88dBm G -96dBm

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Page48

ECS C 

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

Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.

Page49

De finition of Cla s s ma rk 

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: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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Page50

Cla s s ma rk Upda te Flow 

For dual-band MS, after the SCCP connection is established and before receiving message "CM Service Accepted" there will be a class mark update flow.



MS

BSS

MSC

Classmark Request Classmark Enquiry

CR message reports the information of Classmrk 2. And in the class mark

Classmark Change

update flow, MS will report Classmark

Classmark Update

3 information which is related to the dual-band capability.

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Page51

Informa tion a bout Cla s s ma rk 2/3

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Page52

Eme rge nt Ca ll Dis a ble 

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

Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.

Page53

Ce ll S e le ction/Re s e le ction P a ra me te rs 

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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Page54

Ce ll S e le ction P roce s s 



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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Page55

S tore d Lis t Ce ll S e le ction Search the BCCH which have been stored Can decode any frequency?

No

Normal cell selection

Yes

Can reside in any cell ?

No

Yes

Try to reside in its neighbor cell?

Yes

Come into idle mode

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Page56

No

Norma l Ce ll S e le ction Search 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

YES

Is it a BCCH carrier?

YES

Right PLMN&C1>0& priority is Normal ?

All frequency not satisfy Come into idle mode

YES

Right PLMN&C1>0& priority is Low ?

All frequency not satisfy No YES

Stay in a cell(RX-LEV is strongest, C1>0 , cell priority is not prohibited) without considering the PLMN

Decode SCH, read cell para. on BCCH No

No

Emergency call mode

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

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Page57

Ce ll S e le ction P a ra me te r C1=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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Page58

RXLEV_ACCES S _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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Page59

MS _TXP WR_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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Page60

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.



Location: Cell Attributes/Idle Mode/Basic Idle Parameters

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Page61

CBQ 

Value Range: No, Yes



Default Value: No



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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Page62

Applica tion of CBA a nd CBQ CBA

CBQ

Cell Selection Priority

Cell Reselection Priority

No

No

Normal

Normal

Yes

No

Forbidden

Forbidden

No

Yes

Low

Normal

Yes

Yes

Low

Normal

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Page63

Applica tion 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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Page64

Applica tion of CBA

A B

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

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Page65

Ce ll Re s e le ction P roce s s 

Cell reselection for cells in the same location area 



Cell reselection for cells in different location areas 







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.

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.

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Page66

Ce ll Re s e le ction P a ra me te r 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<0 H(PT-T)=1, when PT-T ≥ 0

For serving cell: H(PT-T) = 0

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Page67

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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Page68

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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Page69

PT 

Value Range: 0~30(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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Page70

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

Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.

Page71

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

Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.

Page72

Othe r P a ra me te rs 

PWRC

TCH Immediate Assignment



Cell Extension Type

Immediate Assignment Optimization



Max TA



Interference Band Threshold



Interference Calculation Period



UL DTX



Call Reestablishment Forbidden

   

Direct Retry Assignment Cell Load Judge Enable



Cell Direct Try Forbidden Threshold



DL DTX



Directed Retry Load Access Threshold



T200 and N200



Min Power Level for Direct Try



Use LAPDm N200



Max Resend Times of Phy. Info.



T3105

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Page73

Ca ll Re e s ta blis hme nt Forbidde n 

Value Range: Yes, No



Default Value: Yes



Description: Informing MS whether call reestablishment is allowed or not.



Location: Cell Attributes

Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.

Page74

TCH Imme dia te As s ignme nt 

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

Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.

Page75

Imme dia te As s ignme nt Optimiza tion 

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

Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.

Page76

S igna ling Flow of Imme dia te As s ignme nt Optimiza tion MS

BTS Channel_req

BSC

MSC

Channel_Required MS

Channel_Active

BTS

Channel_Active_Ack

BSC

CHAN_ACT

IMMEDIATE ASSIGN COMMAND First SABM UA

Establish_IND (CM Service Req) CR(Complete_L3_ information)

IMM_ASS_CMD CHAN_ACT_ACK

CC (NOTE 1)

CM Service Accepted

…

Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.

Page77

Dire ct Re try 

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

Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.

Page78

As s ignme nt Ce ll Loa d J udge Ena ble 

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 Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.

Page79

Ce ll Dire ct Try Forbidde n Thre s hold 

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

Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.

Page80

Dire cte d Re try Loa d Acce s s Thre s hold 

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

Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.

Page81

Min P owe r Le ve l for Dire ct 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 cell.



Location: Cell Attributes/ Handover Data/Advanced/HO Control

Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.

Page82

Ma x Re s e nd Time s of P hy. 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 Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.

Page83

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 SABM frame from MS, BTS re-sends physical information to MS and restarts the timer T3105.

Location: Cell Attributes/Handover Data/Advanced/Cell HO Data

Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.

Page84

Intra -BS C Ha ndove r S igna ling Flow MS

BTS1

BSC

BTS2

MS

Measure Report from MS Channel_Active Channel_Active_Ack HANDOVER COMMAND Handover Access PHYINFO PHYINFO First SABM UA

Handover_Detect

Establish_IND

HANDOVER COMPLETE Handover_Performed

Copyright Š 2009 Huawei Technologies Co., Ltd. All rights reserved.

Page85

MSC

P WRC 

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

Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.

Page86

Ce ll Exte ns ion 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

Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.

Page87

Ma x 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

Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.

Page88

Inte rfe re nce Ba nd Thre s hold 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 1 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 Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.

Page89

Inte rfe re nce Ca lcula tion P e riod 

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

Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.

Page90

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

Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.

Page91

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

Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.

Page92

T200 a nd 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, FACCH and SACCH. This is because these channels have different transmission rate.

Location: Cell Attributes/Call Control/Advanced/Timer

Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.

Page93

Us e LAP Dm 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

Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.

Page94

Ce ll Da ta Ma pping in Diffe re nt S ta tus e s of MS Power on

Dedicated Mode (Call Control Para.)

BA2 / RLT / MBR NCC Allowed / PWRC Emergent Call Disabled Call Re-establishment Forbidden UL DTX / DL DTX SACCH Multi-Frames Max Resend Times of Phy. Info. / T3105 Max TA T200 and N200 Use LAPDm N200 TCH immediate assignment Immediate assignment optimization Direct Retry Para.

Select Network (Network Identity Para. )

CGI BSIC

Cell Selection (Cell Selection Para.)

C1(RXLEV_ACCESS_MIN/ MS TXPWR_MAX_CCH) CBA, CBQ

Cell Reselection Mode (Cell Reselection Para.)

C2 (CRO,TO,PT,PI) CRH DSC

Access Network (Call Control Para.)

MS MAX Retrans ECSC Common/Special Access Control Class TX-integer / RACH

Idle Mode (Idle Mode Para.)

BA1 Interference Band Threshold/ Interference Calculation Period

Paging Mode (Idle Mode Para.)

ATT T3212 CCCH Conf BS_AG_BLKS_RES BS_PA_MFRAMES

Min. Access Level

Copyright Š 2009 Huawei Technologies Co., Ltd. All rights reserved.

Page95

De s criptions 1.

Cell Parameters Overview

2.

Cell Parameters Introduction

3.

Case Study

Copyright Š 2009 Huawei Technologies Co., Ltd. All rights reserved.

Page96

Ca s e 1: Is la nd Effe ct 

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.

B

-80

-92

-95

A

C Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.

Page97

Ca s e 2: Incorre ct CGI Ca us e s MS Una ble to Re gis te r on the Ne twork 

Case description 



Cause analysis 



Th e s u b s c rib e r c o m p la in e d t h a t MS c o u ld n o t r e g is t e r t o t h e n e t w o r k , o r it w a s d iffic u lt t o re g is t e r t o t h e n e t w o rk b e t w e e n BTS A a n d B, o r n o n e t w o r k m a r k w a s d is p la y e d o n t h e MS , b u t MS in d ic a t e d t h a t t h e s ig n a l w a s v e ry g o o d . S o m e s u b s c rib e rs a ls o c o m p la in e d t h a t MS c o u ld m a k e MTC c o u ld n o t m a k e MO C.

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.

Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.

Page98

Ca s e 3: RXLEV_ACCES S _MIN Ca us e s S igna l Fluctua tion 

Case description 



Handling procedure 



Subscribers complain that the signal fluctuates in a certain area. Onsite 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.

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.

Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.

Page99

Ca s e 4 ： Too S ma ll T3212 Ca us e s MS Los e Conne ction with Ne twork 

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.

Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.

Page100

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