02...System Info Parameters

7/31/2019 02...System Info Parameters

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All Rights Reserved Alcatel-Lucent 2009

System Info Parameters


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All Rights Reserved Alcatel-Lucent 2009Page2

System Information OverviewSystem Information Overview

System information (SYS INFO) contains network parameters

sent to MS through Um interface.Via system informations, MSs are able to exactly select, access

and cooperate with the network through which different kindsof service is provided.

System information can be sent through two kinds of logical

channels

System information on BCCH

System information on SACCH


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ContentsContents

1. System Information Overview2. Parameters Introduction

3. Case Study


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Introduction to SYS INFO ParametersIntroduction to SYS INFO Parameters

Huawei GSM System Information Parameters:

Network Identity Parameters

Idle Mode Parameters

Call Control Parameters

Cell Selection and Reselection Parameters

Other Parameters


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Idle Mode(Idle Mode Para.)

Power on

Access Network(Call Control Para.)

Select Network(Network Identity Para. )

SI Mapping in Different Statuses of MSSI 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.)


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Network Identity Parameter CGINetwork Identity Parameter CGI

Network identity parameters mainly include cell global identity

(CGI) and base station identity code (BSIC).

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 currentlylocated.


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Mobile Country CodeMobile Country Code MCCMCC

Definition

MCC consists of 3 decimal numbers. It indicates the homecountry of the mobile subscriber.

Format

MCC is composed of 3 decimal numbers. The coding range isdecimal 000-999.


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Mobile Network CodeMobile Network Code MNCMNC

Definition

MNC is used to uniquely identify a specific GSM PLMNnetwork in a certain country (decided by MCC).

Format

MNC is composed of two decimal numbers. The coding rangeis decimal 000-999.


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Location Area CodeLocation Area Code LACLAC

Definition

To locate the location of MS, the whole area covered by eachGSM PLMN is divided into different location areas. LAC isused to identify different location areas.

Format

LAI contains LAC, which is composed of two bytes. LACadopts hexadecimal coding. The available range is from0001H 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 IdentityCell Identity CICI

Definition

To uniquely identify each cell in the GSM PLMN, the networkoperator needs to allocate one code for each cell, which isthe cell identity (CI). Cell identity, together with LAI, is usedfor identity of each cell in the world. (specification 0303).

Format

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


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Network Identity Parameter BSICNetwork Identity Parameter BSIC

BSIC=NCC+BCC

In GSM system, each BTS is allocated with a color code, which iscalled BSIC. MS can identify two cells with the same BCCH bythe help of BSIC. In network planning, effort should be made tomake sure that BCCH of neighbor cells are different from theserving cells BCCH to reduce the interference. Practically it is

still possible that a same BCCH is re-used in the surroundingcells. For cells using the same BCCH in a relevant neardistance, their BSIC must be different so that MS can identifytwo neighbor cells with same BCCH.


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Definition

NCC is a part of BSIC. MS uses it to distinguish adjacent BTSthat belong to different GSM PLMN.

Format

NCC is composed of 3 bits, with the range of 0 to 7.

Network Color Code (NCC)Network Color Code (NCC)


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Definition

BCC is a part of BSIC. For its function, please refer to abovesections.

Format

BCC is composed of 3 bits. The available range is from 0 to7.

BTS Color Code (BCC)BTS Color Code (BCC)


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Idle Mode ParametersIdle Mode Parameters

ATT (Idle Mode)

CCCH_CONF (Idle Mode)

BS_AG_BLKS_RES (Idle Mode)

BS_PA_MFRAMES (Idle Mode)

T3212 (Idle Mode)

Neighbor Cell Description (Idle Mode-BA1&Handover-BA2)


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ATTATT

Value range: Yes, No

Content It is used to inform MS whether IMSI attach-detach isallowed in this cell. If it is set to Yes, the network will notprocess the connection to the called mobile subscriber whenMS is power-off. Thus network processing time and radioresources are saved. Otherwise the network will process the

connection even though the MS has been powered off.RecommendationYes


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CCCH_CONFCCCH_CONF

Value range: 1 Non-Compounding CCCH, 1 Compounding

CCCH, 2 Non-Compounding CCCHs, 3 Non-compoundingCCCHs, 4 Non-compounding CCCHs.

Content: It is Common Control Channel Configuration. CCCHconfiguration determines the capacity of PCH, AGCH and

RACH. This parameter can be automatically configured by theBSC Data Auto Configuration System according to the TRXchannel configuration.

Recommendation: When there is one TRX in the cell, onecombined CCCH is recommended (in a system with few pagingmessages in location area). For others, it is configuredaccording to the number of TRX in the cell.


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BS_AG_BLKS_RESBS_AG_BLKS_RES

Value range: 0~2 (1 combined CCCH), 0~7 (others)

Unit: Block

Content: It is also called Access Granted Blocks Reserved. It isthe number of CCCH channel message blocks that arereserved in one multi-frame for access granted channels(AGCH).

Recommendation: 2 (non-combined CCCH)


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BS_PA_MFRAMESBS_PA_MFRAMES

Value range: 2 9

Unit: Multi-frame period (51 frames)

Content: It is Paging Channel Multi-frames. It defines thenumber of multi-frames used as a cycle of paging sub-channels.

Recommendation: 2


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T3212T3212

Value range: 0~255

Unit: 6 minutes

Content: It is the Periodic Location Update Timer. It defines theinterval of periodic location update.

Recommendation: 30 (for urban area), 20 (for suburban area)


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LA 1

LA 2

Definition of Location UpdateDefinition of Location Update

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


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LA 2

LA 3

Condition of Location UpdateCondition of Location Update

Periodical location updateMoving into a new LA

LA 1


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Procedure of Location UpdateProcedure of Location Update

BSC

MSC

MS

1Hour

1Hour

1Hour

++ ++ +


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Abnormal OccasionAbnormal Occasion

LA 3

LA 2

LA 1

But I amalwayspowered on

The subscriber

you dialed hasbeen poweredoff


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Reason1 of Abnormal OccasionReason1 of Abnormal Occasion

BSC

MSC

MS

1Hour 1Hour1Hour


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Reason2 of Abnormal OccasionReason2 of Abnormal Occasion

BSC

MSC

MS

1Hour 1Hour 1Hour


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Application of T3212Application of T3212

Even if T3212 setting is less than the system (MSC) querytime, the system will still sometimes voice The subscriberyou dialed is powered off.

A B

T3212=4 T3212=8

LAC

Ping-pong Reselect


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Neighbor Cell DescriptionNeighbor Cell Description

There are table BA1 and table BA2.

Table BA1 describes BCCH frequencies of the adjacent cells to bemeasured when the MS is in idle mode.

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


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Theoretical Neighbor Cells Actual Neighbor Cells

B

CA

D

B

CA

D

Application of Neighbor Cell DescriptionApplication of Neighbor Cell Description


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B

C

A

A

Application of Neighbor Cell DescriptionApplication of Neighbor Cell Description

D


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Call Control ParametersCall Control Parameters

MS MAX Retrans

TX-IntegerRACH Min. Access Level

Radio Link Timeout

NCC Allowed

Common/Special Access Control ClassMBR

ECSC

EC Disable


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MS MAX RetransMS MAX Retrans

Value range: 1, 2, 4, 7

Unit: TimeContent: It is one of the random access control parameters. MS

MAX Retrans is the upper limit of times that MS is allowed tosend Channel Request in one immediate assignmentprocedure.

Recommendation:

Set to 7 for areas with low traffic (suburban or rural area)and the cell radius more than 3 km.

Set to 4 for areas with ordinary traffic (non-busy area in the

city) and the cell radius is less than 3km. Set to 2 for micro-cell

Set to 1 for micro-cell with heavy traffic or with obviouscongestion.

Set to 4 or 7 for satellite transmission BTS.


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TX-IntegerTX-Integer

Value range: 3~12, 14, 16, 20, 25, 32, 50

Unit: RACH timeslot (equals to a TDMA frame, 4.615ms)Content: Used to calculate the number of timeslots in the

interval between multiple channel requests sent by MS.

Recommendation: 20 (If the cell immediate assignment successrate is low, set the S with a larger value. Select 32 for satellitetransmission, so as to reduce satellite transmission delay).

Location: Cell Attributes/Idle Mode/Basic Idle Parameters


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Calculation of SCalculation of S

STx-integer

Non-Combined CCCH Combined CCCH

3, 8, 14, 50 55 414, 9, 16 76 52

5, 10, 20 109 58

6, 11, 25163 86

7, 12, 32 217 115


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Radio Link TimeoutRadio Link Timeout

Value range: 4~64, the step size is 4

Unit: SACCH period (480ms)Content: This parameter is used for MS to decide down-link

disconnection in case of SACCH decoding failures.

Recommendation: 20~56

Location: Cell Attributes/Call Control/Basic Call Control Parameters


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Application ofApplication ofRadio Link TimeoutRadio Link Timeout

Impact of radio link timeout

A B

P Q

Poor coverage


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NCC AllowedNCC Allowed

Value range: Check box, including options 0~7.

Content: Network Color Code, sent in system information 2 and6. It lists NCC that need be measured by MS. If a neighborcells NCC is permitted, MS will report MRs of it to the network.

Recommendation: Subject to the concrete conditions.



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Common Access Control ClassCommon Access Control Class

Value range: Check box, including level 0 forbidden,lever 1

forbidden,, till level 9 forbiddenContent: 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 levelusers. 1 stands for forbidden and 0 for permitted.

Recommendation: 0000000000Location: Cell Attributes/Call Control/Basic Call Control

Parameters


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Special Access Control ClassSpecial Access Control Class

Value range: Check box, including level 11 forbidden,level12

forbidden,, till level 15 forbiddenContent: It is used for load control, permitting or forbidding the

network access of some special level users. 1 stands forforbidden and 0 for permitted.

Recommendation: 00000

Location: Cell Attributes/Call Control/Basic Call ControlParameters


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MBRMBR

Value range: 0~3

Content: Multi-band Reporting. It is used to inform MS to reportthe adjacent cells in a controllable way. It is sent in the SystemInformation 2ter and 5ter.



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Application of MBRApplication of MBR

-92dBm -82dBmA B

C -68dBm

D -90dBm

E -78dBm

F -88dBm

G -96dBm

H -84dBm

GSM1800

GSM900

S


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ECSCECSC


Content: Early Classmark Sending Control. It indicates if an MSin the cell is allowed to use early Classmark sending. SeeProtocol 0408.

Recommendation: No.

Location: Cell Attributes/Call Control/Basic Call Control

Parameters


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EC DisableEC Disable

Value range: Yes, NoUnit: None

Content: Emergence Call Disable. When EC Allowed is set toNo, it means emergency call is permitted. Otherwise it isprohibited.

Recommendation: No



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Cell Selection/Reselection ParametersCell 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 ProcessCell 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 SelectionStored List Cell Selection

Search the BCCH

which have been

stored

Can not find it

Normal cell

selection

Can find it

Can reside in it

Cant reside ,search

neighbor cell

Come into

idle mode

NO

YES


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Normal Cell SelectionNormal Cell Selection

Search all frequency

Rank according to receiving level

Come into idle

mode

Check whether this is a BCCH carrier, getSCH and decode system information

PLMN, C1>0, priority is normal

YES

Check next one

NO

NO

YES


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Check the next frequency by the same step

Check the cell which priority is low, C1>0,PLMN

Come into idle

modeTry the cell which PLMN is allowed in

the SIM card

Stay at a cell which RX-LEV is strongest, C1>0 ,

cell priority is not prohibitedEmergency

call mode

NO

NO

YES

YES

YES

NO

YES

Normal Cell SelectionNormal Cell Selection


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Cell Selection ParameterCell 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

P: Maximum Physical supported transmitting power of MS.


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RXLEV_ACCESS_MINRXLEV_ACCESS_MIN

Value range: 0~63

Unit: LevelContent: It means the minimum receive signal level required for

MS to access a cell.

Recommendation: 8

Location: Cell Attributes


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MS TXPWR_MAX_CCHMS TXPWR_MAX_CCH

Value range: 0~31

Unit: levelContent: This parameter determines the maximum allowed output power of the

MS when it begins to access a cell and has not yet received power control

command.

Recommendation: 5(900MHz), 0(1800MHz)

Location: Cell Attributes/Other Attributes/Advanced/Public Channel Control


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CBACBA


Content: Cell Bar Access, worked together with CBQ to set the priority status ofthe cell in idle mode for cell selection and reselection.

Recommendation: Yes



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CBQCBQ

Value range: Yes , No

Unit: None

Content: Cell Bar Qualify. CBQ only affects the selection of cells but is not

related to cell reselection. It works with CBA to define the access

priorities of cells.

Recommendation: No.



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Application of CBA and CBQApplication of CBA and CBQ

CBA CBQ Cell selectionpriority

Cell reselectionpriority

0 0 normal normal

1 0 forbidden forbidden0 1 low normal

1 1 forbidden normal


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Application of CBQApplication of CBQ

The traffic of cell A and B is heavy. Set these twocells with CBA=1, CBQ=0.

A B


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Application of CBAApplication of CBA

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

B

A


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Cell Reselection ProcessCell Reselection Process

Cell reselection for cells in same location area

If the C2 value of the target cell is higher than that of the serving cellfor longer than 5 seconds, a cell reselection process will beperformed 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 diff b/w C2 of the

serving cell by at least the value of CRH for longer than 5 seconds, alocation update process and the cell reselection process will beperformed.

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 C2within 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 ParameterCell 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

Function H(x)=0, when x0


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CROCRO

Value range: 0~63, the corresponding level value: 0~126dB, steppedevery 2dB.

Unit: None

Content: Cell Reselect Offset. It is a parameter in C2 calculation to givean intentional modification in MS cell reselection.

Recommendation: 0



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TOTO

Value range: 0~7 , the corresponding value is 0~60dB, 7corresponds to Infinite.

Unit: None

Content: Cell Reselect Temporary Offset. It is a parameter in C2criterion to give a temporary modification within PT time.

Recommendation: 0

Location: Cell Attributes/Idle Mode/Advanced/Idle Parameter

PT


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PTPT

Value range: 0~31, the corresponding time is 20~620s. 31 is to changethe formula of C2.

Unit: Sec

Content: Cell Reselect Penalty Time.

Recommendation: 0


PI


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PIPI

Value range: Yes (1), No (0).

Unit: NoneContent: Cell Reselect Parameters Indication, sent on the

broadcast channel of the cell. It is an indication to theexistence of Cell Reselect Offset(CRO), TemporaryOffset(TO) and Penalty Time(PT).

Recommendation: Yes


CRHCRH


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CRHCRH

Value range: 0~14 , the step size is 2

Unit: dBContent: Cell Reselection Hysteresis. It is the parameter used

when cell reselection happens between two location areas.

Recommendation: 4


C St d C2C St d C2


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Case Study:Lets for a microcell,

Temporary Offset= 25 dBCell Reselect Offset = 20 dB.Penalty Time = 25 sec.

Lets assume thatC1 = 33 for both serving cell and the micro cell.Therefore two alternative cases are possible to camp on micro cell:

During time 0 ... 24 sec (within the set Penalty Time) :C2 =C1+ Cell Reselect Offset Temporary Offset * H( Penalty Time

T ) C2 =33+20 -25*1C2=28=> C2 < C1,so MS will be kept in macro layer i.e. target cell ( micro cell

) is NOT attractive.

During time 25 ... (Penalty Time over):C2=C1 + Cell Reselect Offset Temporary Offset * H( Penalty Time

T )C2=33+20-25*0C2=53=> C2 > C1, now target cell is very attractive and the idle mode MS will

camp on the microcell.

Case Study on C2Case Study on C2

Oth P tOth P t


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Other ParametersOther Parameters

PWRC (Power Control Permitted)

UL DTX (Uplink Discontinuous Transmission)

Call Re-establishment Forbidden (RE)

PWRCPWRC


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PWRCPWRC

Value range: Yes, No.

Unit: NoneContent: It is used to indicate MS weather to reduce 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 not in consideration. If it is set to Yes, process it

in the way mentioned above.

Recommendation: Yes

Location: Cell Attributes/Other Attributes/Advanced/Public Channel Control

UL DTXUL DTX


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UL DTXUL DTX

Value range: May use, Shall use, Shall not use.

Unit: None

Content: It is used to indicate whether MS uses DTX function. In

System Information 3, it is 2-bit coding. In System Information

6, it is 3-bit coding. It shows the DTX state of the MS in the

previous measurement period.

Recommendation: Shall use


C ll R t bli h t F biddCall Re establishment Forbidden


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Call Re-establishment ForbiddenCall Re-establishment Forbidden


Unit: NoneContent: Informing MS whether call reestablishment is allowed

or not.

Recommendation: Yes


C ll D t M i i Diff t St t f MSCell Data Mapping in Different Statuses of MS


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Cell Data Mapping in Different Statuses of MSCell Data Mapping in Different Statuses of MS

C t tContents


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ContentsContents

1. System Information Overview

2. Parameters Introduction

3. Case Study

Case StudyCase Study


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Case 1: Island effect

Case Description

During the process of optimization in a certain area, it isfound out that the signal is poor in a certain section ofsuburban highway. The signal strength measured is lessthan -95dBm.

Handling Procedure

Modify the data in BSC. Add neighbor relationship to CellA and B for each other. The coverage problem is thussolved.

C

B

A-92

-80 -95



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Case 2: Incorrect CGI causes MS unable to register on the

network. Case description

The subscriber complained that MS could not register to thenetwork, or it was difficult to register to the networkbetween 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 MTCcould not make MOC.

Cause analysis

CGI of the cell was modified. So the network register flowwas not normal. Although the signal was very good, MScould not get registered in the network.

Recommendation and summary

CGI is a very important parameter and should beconfigured correctly, thus to ensured that the CGI data in

Case Study


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Case Study

Case 3: RXLEV_ACCESS_MIN causes signal fluctuation.

Case description

Subscribers complain that the signal fluctuates in a certainarea. On-site test shows that this phenomenon does exist.From the testing mobile, we can see that there are a lot ofcells signals in this area. Some frequencies are the suburbBTS signals far away from this area. The cell reselection ofMS is rather frequent.

Handling procedure

Modify parameter RXLEV_ACCESS_MIN of all cells in

urban area and make them consistent with each other. Theproblem of signal fluctuation is solved.

Recommendation and summary

In area with complicated coverage, the

RXLEV_ACCESS_MIN of each cell should be kept same.



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Case 4Too 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 workingproperly. But from sometime on, some MS often lost

connection with network suddenly. The complaint fromsubscribers in urban area increased.

Handling procedure

Modify T3212 to 10, i.e. 60 minutes. Modify the

corresponding time of MSC to 180 minutes. Two daysobservation shows no subscriber complaint and theproblem is solved.

QuestionsQuestions


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02...System Info Parameters

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