Layer 3 Messaging

7/30/2019 Layer 3 Messaging

1/27

Layer 3 Messaging


2/27

System Information Messages

Introduction

System information (SYS INFO) contains network parameterssent to MS through air interface (Um), including network

identity parameters, cell selection parameters, system controlparameters and network function parameters


3/27

MS can access the network, perform cell

selection, fully utilize various servicesprovided by the network, and achievefavorable cooperation with the network.

SYS INFO can be divided into two parts:

SYS INFO sent on BCCH, including SYSINFO 1, 2, 3, and 4, which are used by MS

in idle mode.

SYS INFO sent on SACCH, including SYS

INFO 5 and 6 which are used by MS indedicated mode.


4/27

System Information Type 1

It contains random access control information

(RACH) and cell frequency allocation table (i.e. CAtable).

It is transmitted on BCCH

The maximum number of cell frequenciesconfigured in CA (Cell Allocation) is 64.

Due to the restriction of cell channel descriptionformat, the frequencies of a cell cannot beconfigured unlimitedly.


5/27

RACH control parameters

Maximum re-transmitting times (MAX retrans)

Extended transmission timeslots (Tx_interger)

Cell Bar access (CBA, CELL_BAR_ACCESS)Common access control level (AC)

Call reestablish permitted (RE)

Emergency call permitted (EC)


6/27



7/27


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.

SYS INFO 2 contains different parts of the neighbor cell BCCH frequencies.

Via reading and decoding BA1 list, MS can perform cell reselection in idle

mode.

BA table indication is transmitted in system information 2 and 5

Network Color Code Permitted (NCC Permitted) is transmitted on

system information 2 and 6


8/27



9/27


It contains LAI, cell identity, RACH and parametersrelated to cell selection.

It is transmitted on BCCH.

It contains:

Cell Identity

LAI( location area identity)

Control Channel Description

Cell Option

BCCH

Cell Selection Parameter

RACH Control Parameter


10/27

Cell Identity & Location Area Identity

Cell Global Identity (CGI) consists of Location AreaIdentity (LAI) and Cell Identity (CI). And LAI includesMobile 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 theCGI, and decide whether it can register in the networkbased on the MCC and MNC indicated by CGI. At the

same time, it can judge whether the current locationarea is changed, so as to decide whether it is necessaryto start the location updating process


11/27

Cell Option

Power control indication (PWRC)

Discontinuous transmission (DTX)

Radio link timeout


12/27


Cell selection parameters indicate how the MS willbehave after the MS is powered on. It includesthe following parameters:

Cell Selection HystereticMaximum 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(NECI)


13/27



14/27


It consists LAI, RACH, cell selection parameters andoptional CBCH channel information. It is transmittedon BCCH. When the system supports cell broadcastfunction, CBCH together with the CBCH MA describethe configuration of CBCH and the relevant frequencyinformation.


RACH Control ParameterCBCH Channel Description. (optional)

CBCH Mobile (Allocation optional)


15/27

CBCH Channel Description &

CBCH MA

These two parameters are optional. When system

supports cell broadcast, CBCH Channel Desc.

explains the CBCH channel configuration

situation. When CBCH Channel Desc. is infrequency hopping mode, CBCH MA is also

needed.


16/27

Other Parameters

Cell reselection parameter indicator (PI)

Cell Bar Qualify (CBQ)

Cell Bar Access (CBA)

Cell_Reselect_Offset (CRO)

Temporary_Offset (TO)

Penalty_Time (PT)


17/27

System Informtion Type 4


18/27


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 report, and use it as the

basis for handover.


19/27



20/27



21/27

Call Setup Procedure

C ll S P d i h TEMS


22/27

c

c

c

c

c

c

c

Call Setup Procedure with TEMS


23/27

MS

BSS

NSSUSER PSTN

RR Channel Request

RACH AllocateTCH

RR Immediate AssignmentAGCH, Radio Resource = (TCH, Frequency Timeslot),

Time Correction, Frequency Correction

Apply the time & frequency Correction

Tune to the frequency and timeslot

RR SABM + MM CM Service Request

TCH, SAPI = 0

RR UA

TCH, SAPI = 0

SCCP Connection Request + BSSMAP Complete Layer 3 Information

SS7

Check Subscriber authentication

PRESS SEND


24/27

MS

BSS

NSSUSER PSTN

Enable Ciphering

BSSMAP CIPHER MODE COMMAND

Expected Ciphered data from the Mobile

RR Ciphering Mode Command

Mode = CLEAR

Enable Ciphering for Received and transmitted Data

Enable ciphering of data transmitted to

the mobile

RR Ciphering Mode Completed

Mode = CIPHERED

BSSMAP CIPHER MODE COMPLETE


25/27

MS

BSS

NSSUSER PSTN

Call Setup

CC Setup

Dialed Digits

CC Call ProceedingConnecting

AllocateVoice Circuits towards BSS

BSSMAP ASSIGNMENT REQUEST

Voice CircuitRR CHANNEL MODE MODIFY

RR CHANNEL MODE MODIFY ACKNOWLEDGE

BSSMAP ASSIGNMENT Complete

ISUP INITIAL ADDRESS MESSAGE

SS7, Dialed Digits

Alerting ToneSS7

ISUP ADDRESS COMPLETE MESSAGECC ALERTING

CC CONNECT ACKNOWLEDGE

CC CONNECTISUP ANSWER

SS7

Mode Modify

Connected

Conversation

Speech

Speech


26/27

MS

BSS

NSSUSER PSTN

Call Release

CC Disconnect

CC Release

End Button

Disconnect Voice Path

BSSMAP CLEAR COMMAND

BSSMAP CLEAR COMPLETE

ISUP Released

SS7

SS7

ISUP RELEASE COMPLETE

CC Release Complete

ISUP RELEASE

SS7

CALL RELEASED INDICATION

RR Connection Release

FREE

Voice Circuit towards BSS

RR CHANNEL RELEASE

RR UA

RR DISC

FREE

TCH


27/27

Thanks

Layer 3 Messaging

Documents

Transcript of Layer 3 Messaging