SYSTEM Info(L3 Messages)

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System Information

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System Information Overview

System information (SYS INFO) contains network parameters sent

to MS through Um interface

network identity parameters (CGI, CID)

cell selection parameters

system control parameters

network function parameters

System information can be sent through two kinds of logical

channels

System information on BCCH (IN the IDLE mode)

System information on SACCH (Dedicated mode)


SYS INFO 1

SYS INFO 1

It contains random access control information (RACH) and cell

frequency allocation table (i.e. CA table). It is transmitted on BCCH.

Content

SYS INFO 1

Cell Channel Description

(cell channel description format)

RACH Control Parameter

(random access channel control parameter)


SYS INFO 1 - Control Parameter

These control parameters include:

Maximum re-transmitting times (MAX retrans)

Extended transmission timeslots (Tx_integer)

Common access control level (AC)

Call reestablish permitted (RE)

Emergency call permitted (EC)

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MS MAX Retrans

Value Range: 1, 2, 4, 7

Unit: Time(s)

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.

Command: SET GCELLCCBASIC / LST GCELLCCBASIC

T3120 will start after send the first CH Request

T3126 will start after reaching MAX Retrans without receive immediate assignment CMD reselection

T3122 will start after receiving access rejection , access will not be allowed during this timer


Max Retransmissions for Radio Priority 1, 2,

3, 4

Parameter ID:MAXRETRANS1, MAXRETRANS2,

MAXRETRANS3, MAXRETRANS4

Value Range: 1, 2, 4, 7

Unit: Time(s)

Default Value: 7 Times

Description: MAX Retransmissions is the upper limit of times that

MS is allowed to send Channel Request in one immediate

assignment procedure.

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Max Retransmissions for Radio Priority 1, 2,

3, 4

Maximum retransmission for radio priority 1, 2 4. The 2bit

Radio Priority message carried by the MS in the Packet

Channel Request message has four levels of priorities. Level 1

is the highest priority, and level 4 is the lowest priority.

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MML: SET GCELLPRACH


TX-integer

Parameter ID: TX

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

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

Default Value: 32

Description: Used to calculate the number of timeslots in

the interval between multiple channel requests sent by

MS.

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MML: SET GCELLIDLEBASIC

(0, 1, 2, , Max(T, 8) -1)

(S, S+1, S+2, ., S+T-1)

TX-integer should be increase in case of AGCH or SDCCH is

overloaded or RACH collision become serious


Calculation of S

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STX-integer

Non-Combined CCCH Combined CCCH

3, 8, 14, 50 55 41

4, 9, 16 76 52

5, 10, 20 109 58

6, 11, 25 163 86

7, 12, 32 217 115


SYS INFO 2

SYS INFO 2

It contains access control information (RACH), network color code permitted (NCC Permitted), and neighbor cell frequency allocation list

(BA1 list). It is transmitted on BCCH. Generally speaking, SYS INFO 2,

2BIS, 2TER contains different parts of the neighbor cells BCCH frequencies. Via reading and decoding BA1 list, MS can perform cell

reselection in idle mode. For a MS of GSM900 PHASE I, it only reads the

neighbor cell BCCH frequencies defined in SYS INFO 2, and ignores

those carried by 2BIS and 2TER.

Content

SYS INFO 2

Neighbor Cell BCCH Frequency Description

NCC Permitted


EXT IND bit = 0 means Sys Info 2 will carry all

BA1 list

EXT IND bit = 1 means Sys Info 2 will carry

part of BA1 list and Sys Info 2BIS will carry the

remaining list


NCC Permitted

Parameter ID: NCCPERMIT

Value Range: Selection of 0~7 Perm.

Default Value: 11111111

Description: Network Color Code. It lists NCC that need

be measured by MS. If a neighbor cells NCC is

permitted, MS will report MRs of it to the network.

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SYS INFO 2BIS

SYS INFO 2BIS

2BIS contains RACH control data and neighbor cells BCCH

frequencies (part of BA1 list). It is optional and transmitted on BCCH.

As the number of frequencies in BA1 list carried by SYS INFO 2 is

limited, SYS INFO 2BIS carries the rest of the BCCH frequencies in

the BA1 list that are from the same band as in SYS INFO 2.

Content

SYS INFO 2BIS

Neighbor Cell Description.

RACH Control Parameter (Same as those in SYS INFO 1)


SYS INFO 2TER

SYS INFO 2TER

2TER contains neighbor BCCH frequencies (part of BA1

list). It is transmitted on BCCH. Only dual band MS can

read this information, and single band 900 or 1800 MS will

ignore it. Since this information carries BCCH frequencies

that belong to different band other than those in SYS INFO

2, it is unnecessary for single band MS to read.

Content

SYS INFO 2TER

Neighbor Cell Description (extended)


SYS INFO 3

SYS INFO 3

It contains LAI, cell identity, RACH control parameters and

cell selection related parameters. It is transmitted on BCCH.

It is one of the most important information.

Content

SYS INFO 3

Cell Identity

LAI (location area identity)

Control Channel Description

Cell Option

Cell Selection Parameter



Cell Identity and Location Area Identity

Cell Global Identity (CGI) consists of Location Area Identity

(LAI) and Cell Identity (CI). And LAI includes Mobile Country

Code (MCC), Mobile Network Code (MNC), and Location Area

Code (LAC). SYS INFO 3, 6, and 4 contain all or part of the

information of CGI. According to the received SYS INFO, MS

decodes the CGI, and decide whether it can register in the

network based on the MCC and MNC indicated by CGI. At the

same time, it can judge whether the current location area is

changed, so as to decide whether it is necessary to start the

location updating process.


Control Channel Description

Control channel description includes the following parameters

IMSI Attach-Detach Allowed (ATT)

Common Control Channel Configuration (CCCH_CONF)

Access Granted Blocks Reserved (BS_AG_BLKS_RES)

Paging Channel Multi-frames (BS_PA_MFRAMES)

Periodic Location Update Timer (T3212)


Cell Option

Cell option contains the following parameters:

Power control indication (PWRC)

Discontinuous transmission (DTX)

Radio link timeout



Cell selection parameters indicate how the MS should behave

after the MS is powered on. It includes the following

parameters:

Cell Reselection Hysteresis (CRH)

Maximum power level of control channel

(MS_TXPWR_MAX_CCH)

Minimum receiving level of MS permitted to access

(RXLEV_ACCESS_MIN)

Additional reselection parameter indicator (ACS)

Half-rate supported (Support Half-Rate)


MS_TXPWR_MAX_CCH

Parameter ID: FMSMAXOPCC

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.

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MML: SET GCELLCCCH

GSM: 5(33dBm) to 19(5dBm)

DCS: 0(30dBm) to 15(2dBm)


CRH(Cell Reselect Hysteresis)

Parameter ID: 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.

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Period of Periodic Location Update(T3212)

Parameter ID: T3212

Value Range: 0~255

Unit: 6 minutes

Default Value: 20

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

the interval of periodic location update.

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ATT (Attach-detach Allowed)

Parameter ID: ATT

Value Range: Yes, No

Default ValueYes

Description: It is Attach-detach allowed. It is used to inform MS

whether IMSI attach-detach is allowed in this cell. If it is set to

Yes, the network will not process the connection to the called

mobile subscriber when MS is power-off. Thus network processing

time and radio resources are saved. Otherwise the network will

process the connection even though the MS has been powered off.

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ATT = Yes attach process

ATT = No, LAI changed Location update


Paging Resources

What kind of CCCH channels are configured?

Decided by parameter: CCCH Conf

How many CCCH blocks are used for PCH in one 51 multi-frame?

Decided by parameter: BSAGBLKSRES (CCCH Blocks Reserved for

AGCH)

How many 51 multi-frame is one paging cycle?

Decided by parameter: BS_PA_MFRMS

How does the MS know which PCH block belongs to it?

Calculated by CCCH grouping and IMSI of MS

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CCCH Conf

Value Range: 1 Compounding CCCH , 1 Non-Compounding CCCH,

2 Non-Compounding CCCHs, 3 Non-compounding CCCHs, 4 Non-

compounding CCCHs.

Default Value: When there is one TRX in the cell, one combined CCCH

is recommended (in a system with few paging messages in location

area). For others, it is configured according to the number of TRX in

the cell.

Description: It is Common Control Channel Configuration. CCCH

configuration determines the capacity of PCH, AGCH and RACH. This

parameter can be automatically configured by system according to the

TRX channel configuration.

Location: This parameter depend on channel configuration

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#of CCCH Blocks : 3,9,18,27 or 36

3 combined BCCH

9 Main BCCH

18,27,36 extended BCCH

1comp combined BCCH

1Non comp main BCCH

2Non Comp main BCCH +

extended BCCH

3Non comp main BCCH +

2 extended BCCH


BSAGBLKSRES (CCCH Blocks Reserved for AGCH)

Parameter ID: BSAGBLKSRES

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: BS-AG-BLKS-RES, indicating the number of the

CCCH message blocks reserved for the AGCH. After the CCCHs

are configured, the value of this parameter indicates the actual

seizure rates of the AGCHs and the PCHs over the CCCHs.

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All AGCH is occupied

There is free PCH block

Use it to send immediate assignment command


BSPAMFRAMS (Multi-Frames in a Cycle on the Paging CH) Parameter ID: BSPAMFRAMS

Value Range: 2~9

Unit: Multi-frame period (51 frames)

Default Value: 2 Multi-frame period

Description: It is Paging Channel Multi-frames. It defines the

number of multi-frames used as a cycle of paging sub-channels.

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CCCH block contains 4 TS & can carry 2IMSI

paging or 4TMSI paging or 2immediate

assignment AGCH


Paging Times

Value Range:1~8

Unit: Times

Default Value: 4

Description: This parameter is used for BTS to

determine whether paging is resent. Together with the

paging times configured in MSC, they jointly control the

paging resend times. The total paging times are

approximate to be the multiplication of the two.

Location: Cell Attributes/Call Control/Basic Call Control

Parameters

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PWRC

Parameter ID: CANPC

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.

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MML: SET GCELLCCCH


SYS INFO 4

It consists LAI, RACH control parameters, cell selection parameters and optional CBCH channel information. It is transmitted on BCCH. When the cell supports cell broadcast function, CBCH together with CBCH MA describe the configuration of CBCH the relevant frequency information.

Content

SYS INFO 4

LAI



CBCH Channel Description (optional)

CBCH Mobile Allocation

SI4 Rest Octets (parameters related to cell reselection)

SYS INFO 4


CBCH Channel Description and CBCH MA

These two parameters are optional. When system supports

cell broadcast, CBCH Channel Description explains the CBCH

channel configuration situation. When CBCH Channel is in

frequency hopping mode, CBCH MA is also needed.


SI4 Rest Octets

It contains the following parameters:

Cell Reselection Parameter Indicator (PI)

Cell Bar Qualify (CBQ)

Cell Bar Access (CBA)

Cell Reselect Offset (CRO)

Temporary Offset (TO)

Penalty Time (PT)


SYS INFO 5

SYS INFO 5

It describes the neighbor cell BCCH frequencies(BA2 list). It is

mandatory and is transmitted on SACCH. Different from SYS INFO 2,

MS can read the frequency described in SYS INFO 5 in dedicated

mode, report the relevant information of neighbor cells in

measurement reports, and use it as the basis for handover. Similarly,

for 900 MS of PHASE 1, it only recognizes the neighbor cell

frequencies described by SYS INFO 5, and ignores those carried by

SYS INFO 5BIS and 5TER.

Content

SYS INFO 5

Neighbor Cell Description.


SYS INFO 5BIS

SYS INFO 5BIS

5BIS describes neighbor cells BCCH frequencies.These

frequencies are part of BA2 list. It is optional and is

transmitted on SACCH. Generally, as the number of

frequencies which can be described by SYS INFO 5 is

limited, SYS INFO 5BIS carries the rest BCCH frequencies

in the BA2 which belong to the same band as SYS INFO 5.

Content

SYS INFO 5BIS

Neighbor Cell Description


SYS INFO 5TER

SYS INFO 5TER

5TER describes neighbor cells BCCH frequencies, these

frequencies are also a part of the BA2 list. It is transmitted

on SACCH. Similarly, only dual band MS can read this

information, and single band GSM900 or GSM1800 MS will

ignore it. It carries the BCCH frequencies of neighbor cells

whose band are different from the serving cells.

Content

SYS INFO 5TER

Neighbor Cell Description (Extended)


SYS INFO 6

SYS INFO 6

It describes LAI, cell identity, and some parameters

describing the cells functions. It is transmitted on SACCH.

It is also one of the most important system information.

Content

SYS INFO 6

Cell Identity

LAI

Cell Option

NCC Permitted

SYSTEM Info(L3 Messages)

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