包-lte库GSMCSFB技术研讨

LTE/GSM

CSFB技术研讨广州2013-03-12移动通信

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内容CSFB

简介EPC/LTE简介CSFB关键信令/流程CSFB

KPICSFB性能优化移动通信

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–话音回落多种方案R8重定向R9重定向（带系统消息）PSHO优化用户体验Fast

Return

or

Fast

Re-direct移动通信

全球多数LTE运营商采用的方案m

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CSFB性能比较优化后的CSFB性能已接近2G/3G语音呼叫移动通信

通信人才网

内容CSFB

简介EPC/LTE简介CSFB关键信令/流程CSFB

KPICSFB性能优化移动通信

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缩略语CSFB：Circuit

Switch

Fall-Back

for

Voice,

即:LTE语音业务回落到电路域完成MO：Mobile

Originating

Call，即：起呼方、主叫MT：MobileTerminating

Call，即：被叫方、被叫Reselection：小区重选HO：切换Redirection：重定向RAT：Radio

Access

Technology，3GPP的无线接入技术IRAT：inter

RAT，通常指3GPP接入技术间的互操作，例如2/3G和LTE的互操作移动通信

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LTE

+

EPC移动通信m

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LTE系统节点移动通信m

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移动通信

基于Gn/Gp的PS域2/3G+4G互操作SGiGnGnS1-MMEPCRFGxS6aHSSS10UEGERANUTRANGn/GpSGSNE-UTRANMMES11S5SGWPGWOperator's

IP

Services(e.g.

IMS,

PSS

etc.)RxGrS1uIP连接通过Gn/Gp接口的4G与2/3G互操作原理上是MME/PGW对SGSN仿真SGSN/GGSN。好处是可以减少对2/3G

GPRS

网的升级改造。m

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CSFB系统构架EPS

architecturefor

CS

fallback

over

SGsUEE-UTRANMMELTE-UuS1-MMEGERANUTRANUmUuSGSNMSCServerSGsGsAGbIu-psS3/Gn

Iu-cs移动通信m

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协议栈–控制面移动通信m

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协议栈–用户面移动通信m

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PDN

connectionData

BearerSRB0Data

BearerSRB

1SRB

2CCCH:

RRC

connection

request/setupDCCH:L1/L2

and

measurement

configurationPaggyback

NASNAS移动通信

承载的逻辑：Radio

Bearer–终端侧用户面mPrivilegeandCon通fide信nt人ial才网

控制面RRC

(UE/eNB/MME)ConnectedidleLTE

UE

移动性管理和主要状态机EMM

(UE/MME)RegisteredDeregisteredESM(UE/MME)–

Always

onGPRS

PDP

context(UE/SGSN)ActivatedDeactivated小区重选小区切换移动通信

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移动寻通信呼论区坛

域www.：区、位置区和路由区LTE

–

tracking

areaTAI=PLMN

id

+

TACGSM

–

Location

areaLAI

=

PLMN

id+LACGPRS

–

Routing

areaRAI

=

PLMN

id+LAC+RACm

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UE

IDSGSNP-TMSIMSCTMSI2/3G

CorePGW:IP

addressMME:

M-TMSISGSN:

P-TMSIMSC:

TMSI移动通信m

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LTE基本消息和信令RRC

-

Radio

Resource

Control系统消息SI本小区信息，邻区信息。LTE用于空闲态移动管理。GSM移动管理：在空闲态BCCH，连接态在SACCH无线资源连接建立、无线层L1/L2的配置无线测量管理NAS

–

Non

Access

Stratum

Signaling移动管理MM网络附着Attach、Detach区更新TAU会话管理SM承载Bear建立，修改和移动通信m

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系统广播消息LTESIB1,小区识别信息SIB2,本小区接入信息SIB3,小区重选设定SIB4,同频4G邻区信息SIB5,异频4G邻区信息SIB6,TDS邻区信息SIB7,GSM邻区信息。。。GSMSIB1本小区频点…SIB2邻区频点…SIB2bis邻区扩展的BCCH…SIB2ter,跨band邻区…SIB2Q,3/4G邻区...SIB3,小区识别信息LAC/CI,小区选择控制，接入信息…SIB4,LAC,本小区选择控制…SIB5,邻区频点…SIB5Bis,邻区跨扩展BCCH…SIB5ter,邻区跨band频点…SIB6,本小区识别信息LAC、CI…SIB13,本小区GPRS接入信息…移动通信

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移动通信

GSM

SIB1：本小区频点••••••••••SYSTEM_INFORMATION_1cell_chan_desc

format_id

=

2

(0x2)

format_id_2

=

1

(0x1)

format_id_3

=

3

(0x3)

ccd_format

var_bit_map=

621

(0x26d)

1

7

=

42

(0x2a)

('0101010'b)

8

15

=33

(0x21)

('00100001'b)•1623

=0

(0x0)

('00000000'b)•2431

=

0

(0x0)

('00000000'b)•3239

=

0

(0x0)

('00000000'b)•4047

=

0

(0x0)

('00000000'b)•4855

=

0

(0x0)

('00000000'b)•5663

=

0

(0x0)

('00000000'b)•6471

=

0

(0x0)

('00000000'b)•7279

=

0

(0x0)

('00000000'b)•8087

=

0

(0x0)

('00000000'b)•8895

=

0

(0x0)

('00000000'b)•96_103

=

0

(0x0)

('00000000'b)•••••••••••••_104_111

=

0

(0x0)

('00000000'b)rach_ctrl_params

max_retrans=

2(0x2)

tx_int

=

14

(0xe)

cell_barr_access

=0

(0x0)

re

=

1

(0x1)ac

=

0

(0x0)

si_1_restpadding_bits_L

=0

(L)

Band

indicatorBAND_INDICATOR_L

=

0(L)spare_padding0_count

=6(0x6)

spare_padding0

=

0

(0x0)•m

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移动通信

GSM

SIB3：LAC/ID,接入信道chan_type

=

1

(0x1)

l2_pseudo_len=

18

(0x12)

trans_id_or_skip_ind

=

0

(0x0)prot_disc

=

6

(0x6)

(GSM_RR_MANAGEMENT)

msg_type

=

27

(0x1b)prot

rr_man_protSYSTEM_INFORMATION_3cell_identcell_ident_val

=

19617

(0x4ca1)

loc_area_identmcc_1

=

4

(0x4)

mcc_2

=

6

(0x6)

mcc_3

=

0

(0x0)

mnc_3

=

15

(0xf)

mnc_1

=

0

(0x0)

mnc_2

=

0

(0x0)loc_area_code

=

22457

(0x57b9)

control_chan_descmscr

=

1

(0x1)

att

=

1

(0x1)bs_ag_blks_res

=

2

(0x2)

ccch_conf

=

2

(0x2)

cbq3

=

0

(0x0)

bs_pa_mfrms

=

0

(0x0)t_3212_timeout=

20(0x14)cell_options

pwrc

=

1

(0x1)

dtx

=

1

(0x1)radio_link_timeout

=7(0x7)

cell_sel_params

cell_reselect_hys

=

5(0x5)

ms_txpwr_max_cch

=

5

(0x5)

acs

=

0

(0x0)neci

=

1

(0x1)

rxlev_access_min

=

10

(0xa)

rach_ctrl_params

max_retrans

=

2

(0x2)

tx_int

=

12

(0xc)

cell_barr_access

=

0

(0x0)

re

=

1

(0x1)ac

=

0

(0x0)

si_3_rest••••••••••••••••••••••••••••••••••••••••••••••Optional

Selection

Parameters

padding_bits_H

=

1

(H)

Selection

ParametersmPrivilegeandCon通fide信nt人ial才网

移动通信

GSM

SIB

2Quater：3/4G邻区••••••••••••••••••••••••••••••••••••••••••…SYSTEM_INFORMATION_2QUATERsi_2quater_rest…SI2quater_INDEX

=

3

(0x3)

SI2quater_COUNT

=

3

(0x3)……e_utran_measurement_parameters_description_present

=

0

(0x0)

gprs_e_utran_measurement_parameters_description_present

=

0

(0x0)

struct0_count

=

1

(0x1)struct0[0]

const_1=

1(0x1)Repeated

E-UTRAN

Neighbour

Cells

struct0_count

=

2

(0x2)struct0[0]

const_1

=

1

(0x1)=38000

(0x9470)measurement_bandwidth_present

=

0

(0x0)

struct0[1]const_1

=

1

(0x1)=38950

(0x9826)measurement_bandwidth_present

=

0

(0x0)const_0=

0

(0x0)

e_utran_priority_present

=

1

(0x1)

E-UTRAN_PRIORITY

=

7

(0x7)

THRESH_E-UTRAN_high

=

10

(0xa)thresh_e_utran_low_present

=

1

(0x1)

THRESH_E-UTRAN_low=

20

(0x14)e_utran_qrxlevmin_present

=

1

(0x1)

E-UTRAN_QRXLEVMIN

=

5

(0x5)const_0=

0

(0x0)

struct1_count

=

0

(0x0)

const_0=

0

(0x0)

struct2_count

=

0

(0x0)

const_0=

0

(0x0)_3g_csg_description_present

=

0

(0x0)

e_utran_csg_description_present

=

0

(0x0)

padding_bits_L

=0

(L)

spare_padding0_count

=56

(0x38)

spare_padding0

=0x00000000000002595Mhz2330Mhzm

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移动通信

RRC：配置UE-eNB接入协议m

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RRC建立SRB0SRB1MSG3MSG4e.g.

NAS:Attach

or

MO

CSFBTM,

SR

config,

SRB

config.RRC

Security

Mode

CommandRRC

Security

Mode

Command

completeSRB

2移动通信m

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连接建立的业务触发“Service”->UERespond

to

a

pageCS

page

CSFB

MTPSpageDL

dataNetwork

initiated

NAS

msg- UEinitiated

NAS

msgESR:

CSFB

MOTAUAttach/Detach

…SR-

…rrcConnection…SRB2:

NASDRB:data移动通信m

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RRC：承载控制信令UE->eNB:

RRC

connection

request由业务触发，例如ESR或SRRRC

connection

setup配置SRB1,MAC和物理层RRC

connection

completePiggyback

NAS：

Atta O

CSFB

etc…RRCConnectionReconfiguration配置SRB2和DRBSRB2用来直传NAS消息DL/UL

Information

Transfer移动通信

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移动通信RRwCw全w.部h信ro令pt(S.pceocm36.331)DLSRB0CCCHTMRRCConnectionRejectDLSRB1DCCHAMRRCConnectionReleaseULSRB0CCCHTMRRCConnectionRequestDLSRB0CCCHTMRRCConnectionSetupULSRB1DCCHAMRRC

pleteDLSRB1/2DCCHAMDLInformationTransferULSRB1/2DCCHAMULInformationTransferDLSRB1DCCHAMUECapabilityEnquiryULSRB1DCCHAMUECapabilityInformationDL_PCCHTMPagingDLSRB1DCCHAMmandULSRB1DCCHAMpleteULSRB1DCCHAMSecurityModeFailureDLSRB1DCCHAMRRCConnectionReconfigurationULSRB1DCCHAMRRCConnectionpletem

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DLULDLULSRB0SRB0CCCHCCCHTMTMRRCConnectionReestablishmentRejectRRCConnectionReestablishmentRequestDL_BCCHTMSystemInformationDL_BCCHTMSystemInformationBlockType1DL_BCCHTMMasterInformationBlockDLSRB1DCCHAMCounterCheckULSRB1DCCHAMCounterCheckResponseULSRB1DCCHAMMeasurementReportDLSRB1DCCHAMMo

mandULSRB1DCCHAMCSFBParametersReq

DMA2000DLSRB1DCCHAMCSFBParametersResponseCDMA2000ULSRB1DCCHAMULHandoverPreparationTransfer

(CDMA2000)DLSRB1DCCHAMHandoverFromEUTRAPreparationRequestSRB0SRB1CCCHDCCHTMAMRRCConnectionReestablishmentRRCConnectionplete(CDMA2000)移动通信RRwCw全w.部h信ro令pt(S.pceocm36.331)m

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NAS消息EPS–

移动性管理Attach/detachTAUAuthenticationIdentity

requestSecurity

mode–

移动连接管理Service

requestPagingNAS

transport

(SMS)–

会话管理PDN

connectionEPS

bearer

act/deact/modif.GSM/GPRS–

移动性管理通用AuthenticationIdentity

requestSecurity

modeCS:LAUAttach/detachCall

ControlPS:GMMRAUGMM

attach/detach–

PS会话管理PDP

contextactivate/deactivatPDP

context

modification移动通信m

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DLULDLULAttach

acceptAttach

completeAttach

rejectAttach

requestULDLDLULDLULAuthentication

failureAuthentication

rejectAuthentication

requestAuthentication

responseIdentity

requestIdentity

responseDLULULBHSecurity

mode

commandSecurity

mode

completeSecurity

mode

rejectSecurity

protected

NAS

messageDLULDownlink

NAS

TransportUplink

NASTransportDLULDLULTracking

area

update

acceptTracking

area

update

completeTracking

area

update

rejectTracking

area

update

requestDLULULServicerejectServicerequestExtended

service

requestDLULDetach

acceptDetach

requestDLCS

service

notificationDLULEMM

informationEMM

statusDLULGUTI

reallocation

commandGUTI

reallocation

complete移动通信论N坛AS

EPwS

wMwM.h全ro部p信t.令co(Smpec

24.301)DLPDN

connectivity

rejectDLPDN

disconnect

rejectULPDN

connectivity

requestULPDN

disconnect

requestULULDLULULDLULULDLActivate

dedicated

EPS

bearercontext

acceptActivate

dedicated

EPS

bearer

context

rejectActivate

dedicated

EPS

bearercontext

requestActivate

default

EPS

bearer

context

acceptActivate

default

EPS

bearercontext

rejectActivate

default

EPS

bearer

context

requestModify

EPS

bearer

context

acceptModify

EPS

bearer

context

rejectModify

EPS

bearer

context

requestULDLDeactivate

EPS

bearer

context

acceptDeactivate

EPS

bearer

context

requestDLULDLULBearer

resource

allocation

rejectBearer

resource

allocation

requestBearerresource

modification

rejectBearerresource

modification

requestDLULDLESM

informationrequestESM

informationresESM

statusmPrivilegeandCon通fide信nt人ial才网

移动通信NA(Spec

24.301)内容CSFB

简介EPC/LTE简介CSFB关键信令/流程CSFB

KPICSFB性能优化移动通信

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CSFB信令流程-1联合CSFB主叫流程回归LTE重选重定向移动通信

m

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联合移动通信m

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移动通信

CSFB

–

Combined

AttachMME

to

figure

out

a

VLRfor

CS

service,

the

MSC/VLRcreate

SG

interface

to

MME1.

Attach

RequestDerive

VLR

numberLocation

Update

RequestCreate

SGs

association7.

Location

UpdateAcceptUEMMEHSSMSC/VLR2.

Step

3

to

step

16

of

the

Attach

procedure

specified

in

TS

23.4016.

Location

update

in

CS8.

Step

17

to

step

26

of

the

Attach

procedure

specified

in

TS

23.401m

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m

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Attach

RequestOld

ME/SGSNServing

GWPCRFHSS3.

Identification

RequestPDN

GW2.

AttachRequest3.

Identification

Response4.

Identity

Request4.

Identity

Response5a.

Authentication

/

SecurityUplink

Data23

Modify

Bearer

Request(B)(A)9.

Cancel

Location9.

Cancel

Location

Ack10.

Delete

Session

Request10.

Delete

Session

Response7.

Delete

Sesion

Request7.

Delete

Session

Response8.

Upda ocation

RequestEIR5b.

ME

Identity

Check5b.

Identity

Request/Response10.

PCEF

Initiated

IP-CAN

Session

Termination7.

PCEF

Initiated

IP-CAN

Session

Termination11.

Updaocation

AckCreate

Session

RequestCreate

Session

RequestPCEF

Initiated

IP-CAN

Session

Establishment/Modification(C)Create

Session

ResponseDownlink

Data

(if

not

handover)Create

Session

ResponseInitial

Context

Setup

Request

/

Attach

AcceptRRC

Connection

ReconfigurationRRC

Connection

Reconfiguration

CompleteInitial

Context

Setup

Response6.

Ciphered

Options

Request6.

Ciphered

Options

Response21.

Direct

Transfer22(E)(F)移动通信EU才网联合Attach

RequestAttach

type=2，联合UE

id：GUTI或P-TMSI…esm_msg_container：PDN

connectivity

request

voice_

_pref_for_EUTRAN

=

2

(0x2)

(CSVoice

preferred,

IMS

PS

Voice

as

secondary)UE_usage_setting

=

0

(0x0)

(Voice

centric)移动通信

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联合

被接受Attach

Acceptattach_result

=

2

(0x2)

(comb

EPS/IMSI

attach)t3412

（TAU周期）tai_listloc_area_idms-idgutiesm_msg_container：

msg_type

=

193

(0xc1)

(Activate

defaultEPS

bearer

context

request)qci

=

8

(0x8)

(QC8)access_pointpdn_addrQos移动通信

m

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移动通信

CSFB

–

MO

call

flow,

connected

modeUE/MSMMEBSS/RNSMSCeNodeB10b.

Location

Area

Update10a.

Service

RejectSGW/PGW4

S1-AP:

S1

UE

Context

Release

Request1a.

NAS

Extended

Service

Request1b.

S1-AP

UE

Context

Modification

Request

with

CS

Fallback

indicatorSGSN11.

Routing

Area

Update

or

Combined

RA/LA

UpdateIf

the

MSCis

changed10c.

CS

MO

call9.

CM

Service

Request9.

A/Iu-cs

message

(with

CM

Service

Request)ESR

with

CSFB

indication1c.

S1-AP

UE

Context

Modification

Response

message2.

Optional

Measurement

Report

Solicitation3a.

NACC, .

3b,

3c

RRC

connection

releaseMME

ask

UE

to

tune

away

to

2G/3G5.

S1

UE

Context

Release6.

UE

changes

RAT

then

LA

Update

or

RA

Update

or

LAU

and

RAU7a.

Suspend

(see

23.060)7b.

Suspend

Request

/

Response8.

Update

bearer(s)UE

access

2G/3G

for

CS

callm

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g可以省100~200ms连接态移动通信

通信人才网

移动R通R信C论重坛RRC

release

with

Redirection{10,631,632,633,634,635,636,637,638,639,640}}}}value

DL-DC

essage

::={message

c1

:

rrcConnectionRelease

:{rrc-TransactionIdentifier

3,criticalExtensions

c1:

rrcConnectionRelease-r8

:{releaseCause

other,redirectedCarrierInfo

geran

:{8,bandIndicator

dcs1800,s

ex s

:•••••••••••••••••}mPrivilegeandCon通fide信nt人ial才网

移动通信

R9

RRC

release

with

SI

tunnelingvalue

DL-DC essage

::={message

c1

:

rrcConnectionRelease

:{rrc-TransactionIdentifier

0,criticalExtensions

c1

:

rrcConnectionRelease-r8

:{releaseCause

other,

redirectedCarrierInfo

geran

:{0,bandIndicator

dcs1800,s

ex s

:{560,70}},nonCriticalExtension{nonCriticalExtension{cellInfoList-r9

geran-r9

:{{physCellId-r9{networkColourCode

'010'B,

baseStationColourCode

'000'B},carrierFreq-r9{70,bandIndicator

dcs1800},systemInformation-r9{'

0000000000000100B100002B'H,

'1B4D6864F0005814D2001457A54DB100008000B053'H,

'00E0005878654A92A53B2942DB2B2B2B2B2B2B2B2B'H}},{physCellId-r9{networkColourCode

'011'B,

baseStationColourCode

'001'B•••••••••••••••••••••••••••••••••••••••••••••••mPrivilegeandCon通fide信nt人ial才网

移动E通xa信

plewwwlo.hgro(idle)

R8

redirection

+

MOCSFB_R8_MO_FR_idle_with_attachm

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CSFB信令流程-2CSFB被叫流程TAU

区更新移动通信

m

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IF

THEMSC

ISCHANGEDUE/MSMMEMSC9c.

Location

Area

Update

or

Combined

RA/LA

UpdateS-GW/PGWect9b.Signalling

Connection

Release

9b.

CONNECTION

REJECT1A.

CS

SERVICE

NOTIFICATION1A.

PAGING

REQUESTSGSNeNodeB

BSS/RNS3a.

CCO/NACC, 3b,

3c.Signalling

connection

release4.

S1-AP:

S1

UE

CONTEXT

RELEASE

REQUEST1A.

SERVICE

R1b.

NAS

Extended

Service

Request

1c.

CS

Paging

RejEQUEST1d.

S1-AP

UE

Context

Modification

Request

with

CS

Fallback

indicator1e.

S1-AP

UE

Context

Modification

Response

message2.

Optional

Measurement

ReportS1

UE

CONTEXT

RELEASEUE

changes

RAT

then,

LAU

OR

RA

UPDATE

OR

LAU

ANDRAU7a.

Suspend

(see

TS

23.060)7b.

Suspend

Request

/

ResponseUpdate

bearer(s)Paging

Response9a.Establish

CS

connection移动通信

CSFB

MT

call

flow

-

connected

modePaging

request

from

MSC

viaMMEMME

ask

UE

to

tune

away

to2G/3GUE

access

2G/3G

for

CS

callm

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才网移动通信

Fast

Return

–

RR

channel

releaseIEIInformation

elementType

/

ReferencePresenceFormatlengthRR

managementProtocol

DiscriminatorProtocol

Discriminator10.2MV1/2Skip

IndicatorSkip

Indicator10.3.1MV1/2Channel

ReleaseMessage

TypeMessage

Type10.4MV1RR

CauseRR

Cause1MV173BA

RangeBA

RangeaOTLV6

-

?74Group

Channel

DescriptionGroup

Channel

Description4bO

(note

1)TLV5-138xGroup

Cipher

Key

NumberGroup

Cipher

Key

Number0CTV1CxGPRS

ResumptionGPRS

Resumption4cOTV175BAList

PrefBAList

PrefcOTLV3-?76UTRAN

Freq

ListUTRAN

Freq

ListdOTLV3-?62Cell

Channel

DescriptionCell

Channel

DescriptionbOTV1777Cell

selection

indicator

afterrelease

of

all

TCH

and

SDCCHCell

selection

indicator

afterrelease

of

all

TCH

and

SDCCH

eOTLV4

-

?AxEnhanced

DTM

CS

ReleaseIndicationEnhanced

DTM

CS

ReleaseIndication

4eOTV104VGCS

Ciphering

ParametersVGCS

Ciphering

Parameters2bOTLV3-1578Group

Channel

Description

2Group

Channel

Description

24fO

(note

1)TLV1379Talker

IdentityTalker

Identity5OTLV3-207ATalker

Priority

StatusTalker

Priority

Status4

通信O

人才T网LV

ww3

w.it7BVGCSAMR

ConfigurationVGCSAMR

ConfigurationOTLV32012

Dec

15

05:25:42.173

[00]

0x512F

GSM

RR

Signaling

Message

--Channel

Release…protrr_man_protCHANNEL_RELEASE…cell_select_ind_incl

=

1

(0x1)cell_select_indlength_of_cell_selection_indicator

=

3

(0x3)const_011

=

3

(0x3)struct3_count

=

1

(0x1)struct3[0]const_1

=

1

(0x1)E-UTRAN

Description=

39250(0x9952)measurement_bandwidth_present

=

0

(0x0)not_allowed_cells_present

=

0

(0x0)_pcid_present

=

0

(0x0)…mPrivilegeandCon通fide信nt人ial才网

移动通信

mPrivilegeandCon通fide信nt人ial才网

移动通信

CSFB

–

MT

call

flow

-

idle

mode…TAU流程IRAT基于Gn/Gp24.301,D.3.62.

Tracking

Area

Update

Request3.

Tracking

Area

Update

RequestRNCBSC11.

PCEF

I

atedIP-CANSession

Mod

fication5.

SGSN

Context

Response4.

SGSNContext

RequestGn/GpServingOldPDNMMESGSNGWMMEGWPCRFHSSSecurity

proceduresSGSN

Context

AcknowledgeC1Create

Session

RequestModify

Bearer

Request

(A)1.

Trigger

to

startTAU

procedure移动通信meNodeBModify

Bearer

ResponseCreate

Session

ResponseUpda ocation

RequestCancel

LocationCancel

LocationAckCancel

LocationIu

Release

CommandIu

Release

CompleteCancel

Location

AckUpda

ocation

AckTracking

Area

Update

AcceptTracking

Area

Update

CompleteProcedure

as

in通TS

23信.401,s人teps2才to7

o网f

Figurew5.4(A)UEeNodeBMMEServing

GWPDN

GWPCRFHSS5.

Update

Bearer

Request6.

Procedure

as

in

TS

23.401,

steps

3

to

10

ofFigure

-1

or

steps

3

to

8

of

Figure

5.4.3-17.

Update

Bearer2b.

Modify

Bearer

Command3.

Modify

Bearer

Command4.

PCEF

Initiated

IP

-CANSession

Modifica

tion(B)Response8.

Provision

Ack.

2a.

UE

Ctxt

Update1.

Insert

Subscriberdata1a.

Insert

Subscriber

data

Ack

Figure

-1:

HSS

Initiated

Subscribed

QoS

Modification移动通信m

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(A)MMEServing

GWPDN

GWPCRFeNodeBUE(B)Modification1.

IP-CAN

SessionModificationUpdate

Bearer

RequestUpdate

Bearer

RequestDownlink

NAS

TransportDirect

TransferDirect

TransferUplink

NAS

TransportUpdate

Bearer

Response9.

Update

Bearer

Response10.

IP-CAN

SessionFigure

5.4.3-1:

Bearer

Modification

Procedure

without

Bearer

QoS

Update移动通信

m

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(B)MMEServing

GWPDNGWPCRF11.

Update

Bearer

resUEeNodeB(A)1.

IP-CANSessionModificationionponse12.

IP-CAN

SessModificationUpdate

Bearer

requestUpdate

Bearer

RequestBearer

Modify

Request/Session

Management

RequestRRC

Connection

ReconfigurationRRCConnection

Reconfiguration

CompleteBearer

Modify

ResponseDirect

TransferSession

Management

ResponseUpdate

Bearer

ResponseFigure

-1:

Bearer

Modification

Procedure

with

Bearer

QoS

Update移动通信

m

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移动通信

通信人才网

移动E通xa信

plewwwlo.hgro(idle)

MT

R8

redirection

+

FRm

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小结移动通信

m

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R8

redirection和R9

redirection的比较R8

redirection只携带目标GSM频点UE需要在指定频率集上选择频点，并要花时间读SIB信息R8

redirection携带目标GSM频点和所在频点的小区列表+相应接入必备的系统消息UE只需要在指定频率集上选择小区，不需要花时间读SIB消息，平均可节省可达2秒。移动通信

m

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MO和MT的CSFB比较MOUE发起ESR

CSFB

MO在GSM发起CMService

RequestMTLTE将来自MSC的寻呼转给UE空闲态：PCCH:pagingCS

indicator连接态：CS

ServiceNotificationUE响应ESR

CSFB

MT在GSM响应PagingResponse

而不是CMSR移动通信

m

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同LA和跨LA的比较同LAUE在GSM发起CMService

Request或Paging

response不需要做LAU。通话结束后如未激活FR，先后发起LAU和RAU。跨LAUE在GSM发起CM

ServiceRequest或Paging

response时需要事先做LAUUE在此LAU中标记Follow-On-Request（MO）或CSMT（MT）以保证LAU完成后NAS连接保持顺便做后续的CM_SR或PagingResponse。如果跨MSC，则需要MSC网络开启MTRR/MTRF，否则会造成MT掉话。移动通信

m

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移动回通归信论坛LTE小区重选和快速重定向的比较小区重选reselectionUE进入空闲态后做RAU或LAU/RAU，然后再次进入空闲态。在空闲态读系统消息得到临小区信息。根据重选判据选择LTE小区，也何能由于移动造成当前无线环境变化而进入其他RAT如TDS覆盖。用户活跃数据可能使UE无法短期进入空闲态。快速重定向FRCSFB通话结束，GSM通过RRChannelRelease直接定向UE到指定LTE频率UE在无需做LAU和RAU可快速回到LTE由于UE移动可能导致离开LTE覆盖区，致使FR失败。–需要有能力识别适用

FR终端，否则对一些（例如漫入）客户可能会造成一些问题。m

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连接态CSFB的特点LTE

RRC

连接已经具备，可以省去RRC连接建立时延约100~200msMT连接态时，用CSServiceNotification而不是PCCH:CS

paging。在GSMCSFB通话结束后LAU/RAU后可能会进入数据传输模式，这时应关闭应用，以使UE重选会LTE。移动通信

m

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内容CSFB

简介EPC/LTE简介CSFB关键信令/流程CSFB

KPICSFB性能优化移动通信

m

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KPI呼叫建立时延LTE回归时延电路域不可及时间(G->T)移动通信

m

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CSFB过程空口关键步骤被叫响应被叫流程:paging->ESR(CSFB

indication)LTE

RRC连接建立（空闲态）为了承载NAS信令:ESR

（CSFB

indication/CS

terminatingcall）GSM找网：Turn

away

to

GSMLTE

RRC

触发GSM找网，包括读必要的系统消息（例如SIB2包括小区接入信息）并接入小区GSM语音呼叫流程CM

Service

Request/Paging

Response

->NAS

Setup->Alerting->…->Disconnect->NAS

release->

RR

channelrelease移动通信

m

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通话结束，回归LTE重选回LTE

（Reselection）GSM

RR

release->LAU/RAU->测量找网。。。->读LTE

SIB->TAU->TAU

accept快速定向到LTEGSM

RR

release

带有指定重定向的LTE频点->读LTE

SIB

->

TAU->TAU

accept移动通信

m

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移动通信

L2L

CSFB端到端流程分解m

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移动通信

Exemplary

CSFB

Call

flowNo

UE

processingdelayGSMCS

callflowAdditional

process

than

anormal

GSM

callDelta

in

paging

delay

for

MT

callRRC

connection

for

sending

NASESRTune

away

to

GSMGSM

SIBreadingPCCH:

paging

with

CS

Doman

indicator45:13.4NAS

Extended

service

request:mobile

originating

CS

fallback45:13.4rrcConnectionRequest:

establishmentCause

mo-Data45:13.5rrcConnectionSetup45:13.5rrc

plete45:13.5LTE

ConnectionRelease

to

GSM

=8Tune

away

to

GSM45:14.8SYST