SYSTEM info(L3 messages) 2G.ppt

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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”T3120 will start after send the first “CH Request”T3126 will start after reaching MAX Retrans without receive immediate assignment CMD T3126 will start after reaching MAX Retrans without receive immediate assignment CMD

reselectionreselectionT3122 will start after receiving access rejection , access will not be allowed during this T3122 will start after receiving access rejection , access will not be allowed during this

timertimer


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:MML: SET GCELLPRACH 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:MML: SET GCELLIDLEBASIC SET GCELLIDLEBASIC

(0, 1, 2, ………, Max(T, 8) -1)(0, 1, 2, ………, Max(T, 8) -1)(S, S+1, S+2, ………., S+T-1)(S, S+1, S+2, ………., S+T-1)

TX-integer should be increase in case of AGCH or TX-integer should be increase in case of AGCH or SDCCH is overloaded or RACH collision become SDCCH is overloaded or RACH collision become

seriousserious


Calculation of S

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SSTX-integerTX-integer

Non-Combined CCCHNon-Combined CCCH Combined CCCHCombined CCCH

3,3, 8,8, 14,14, 5050 5555 4141

4,4, 9,9, 1616 7676 5252

5,5, 10,10, 2020 109109 5858

6,6, 11,11, 2525 163163 8686

7,7, 12,12, 3232 217217 115115



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 cell’s 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 EXT IND bit = 0 means Sys Info 2 will means Sys Info 2 will carry all BA1 listcarry all BA1 list

EXT IND bit = 1 EXT IND bit = 1 means Sys Info 2 will means Sys Info 2 will carry part of BA1 list and Sys Info 2BIS will carry part of BA1 list and Sys Info 2BIS will

carry the remaining listcarry 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 cell’s 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 cell’s 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 Parameter

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:MML: SET GCELLCCCH SET GCELLCCCHGSM: 5(33dBm) to GSM: 5(33dBm) to

19(5dBm)19(5dBm)DCS: 0(30dBm) to DCS: 0(30dBm) to

15(2dBm)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 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.

Page26MML:MML: SET GCELLIDLEBASIC SET GCELLIDLEBASIC

ATT = Yes ATT = Yes attach processattach processATT = No, LAI changed ATT = No, LAI changed Location Location

updateupdate


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 #of CCCH Blocks : 3,9,18,27 or 3636

3 3 combined BCCH combined BCCH9 9 Main BCCH Main BCCH

18,27,36 18,27,36 extended BCCH extended BCCH

1comp 1comp combined combined BCCHBCCH

1Non comp 1Non comp main main BCCHBCCH

2Non Comp 2Non Comp main main BCCH + extended BCCHBCCH + extended BCCH

3Non comp 3Non comp main main BCCH + 2 extended BCCH + 2 extended

BCCHBCCH


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 occupiedAll AGCH is occupiedThere is free PCH blockThere is free PCH block

Use it to send immediate assignment Use it to send immediate assignment commandcommand


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 CCCH block contains 4 TS & can carry 2IMSI paging or 4TMSI paging or 2IMSI paging or 4TMSI paging or 2immediate assignment AGCH2immediate 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:MML: SET GCELLCCCH 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− Cell Selection Parameter− RACH Control Parameter− 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 cell’s.

Content

SYS INFO 5TER

− Neighbor Cell Description (Extended)



SYS INFO 6

SYS INFO 6

It describes LAI, cell identity, and some parameters describing the cell’s 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


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SYSTEM info(L3 messages) 2G.ppt