epc网络互操作分析-

目标通过学习本课程，您将：了解EPC与2G3G互操作相关概念掌握EPC与2G3G互操作流程了解EPC与2G3G互操作了解EPC网络部署方案和一般部署步骤内容EPC与2G3G互操作概述EPC与2G3G互操作流程EPC与2G3G互操作EPC网络部署分组网的网络结构普通2/3G

网用户面两级结构控制面和用户面合一通常采用TDM/ATM链路承载扁平化的

网部分控制承载分离ALL

IP承载3G

DTS模式

网扁平化网络控制承载分离ALL

IP承载EPC架构GGSNSGSNSGSN2/3GGERAN/UTRANATM/TDMATM/

TDMIPSGSNGGSNGGSN3G-DTSIPUTRANMMESAE-GWSAE-GWLTE/EPCIP网IP承载方式扁平化的网络控制承载分离GSMTDSCDMANon-3GPPLTEeUTRAN对新网络的需求支持1.25

MHz～20

MHz带宽。峰值数据率：上行50

Mb/s，下行100Mb/s。频谱效率达到3GPPR6的2～4倍。提高小区边缘的比特率。用户面延迟（单向）小于5

ms，控制面延迟小于100ms。支持与现有3GPP和非3GPP系统的互操作。支持增强型的广播多播业务。降低建网成本，实现从R6的低成本演进。实现合理的终端复杂度、成本和耗电。支持增强的IMS（IP多

子系统）和

网。追求后向兼容，但应该仔细

能改进和向后兼容之间的平衡。取消CS（电路交换）域，CS域业务在PS（包交换）域实现，如采用VoIP。对低速移动优化系统，同时支持高速移动。应用场景一LTE与2G3G互操作的两种架构场景一：GnGpSGSNGn/GpGn/GpS1-MMES6aHSSS10UELTE-UuE-UTRANMMES11S5ServingGatewayPDNGatewayS1-UUTRANGn/Gp

SGSNGERAN网络改造GnGp

SGSN与MME的接口基于GTPv1的Gn/Gp接口Gn/Gp

SGSN与PDN-GW之间的接口基于GTPv1的Gn/Gp接口SGSN不需升级应用场景二S12S3S1-MMES6aHSSS10UELTE-UuE-UTRANMMES11S5ServingGatewayPDNGatewayS1-US4UTRANS4

SGSNGERANLTE与2G3G互操作的两种架构场景二：S3S4

SGSN应用场景二LTE与2G3G互操作（Combo

MME）S12S1-MMES6aHSSUELTE-UuE-UTRANComboMME+

S4

SGSNS11S5ServingGatewayPDNGatewayS1-US4UTRANGERAN网络改造S3、S4-C、S5/S8-C、S10、S11基于GTPv2-CS1-U、S4-U、S5/S8-U、S12、Iu-ps基于GTPv1-U需要对原2G

3G网络的SGSN进行升级，支持R8特性，其新增主要功能如下：S3/S4接口支持GTPv2-CS4接口和Iu接口的QoS双栈的处理在切换过程中保持或者激活ISR默认承载的处理重选与Handover比较项目重选HandoverUE状态UE

Idle/standby状态；

UE信令连接状态；UE用户面数据收发状态仅在UE存在报文收发状态下流程发起方UE无线侧（RNC/BSC/eNodeB）业务连续性无业务或者业务短暂中断可保证业务连续性（理论上可以避免不丢包，实际操作可能存在少量丢包无线侧（RNC/BSC/eNodeB）配置无需数据配置需要配置临小区相关信息，以及切换策略，无线侧通知UE测量临小区信号并择机handover对无线和 网要求较低较高流程成功率较高较低LTE网络部署阶段根据移动蜂窝网络发展的一般性规律，LTE网络发展可以分为以下三个阶段，起步阶段（热点地区部署，小规模组网），规模部署阶段，全覆盖阶段（业务与网络成熟）LTE网络互操作模式与发展阶段在阶段1，LTE网络只有热点部署，覆盖很不完善，为减少边缘区域的乒乓效应，建议只进行LTE到2G3G网络的重选和切换，LTE与2G之间的handover不建议实施。在阶段2，LTE大规模部署，与3G网络并重，2G网络基本淘汰，此时建议开通3G与LTE的相互handover（并适时开展基于网络负荷的策略切换），网络重选只开通不带业务的重选。在阶段3，LTE基本

，3G网络逐步萎缩退网，只在部分区域作为补充，此时仅开通3G到LTE的重选和handover。由于2G网络与LTE速率差距悬殊，因此整个LTE网络阶段都不开通到2G网络之间的handover。内容EPC与2G3G互操作概述EPC与2G3G互操作流程EPC与2G3G互操作EPC网络部署2G3G->LTE网络重选流程（S4

SGSN）HSSnew

MMEold

MME/old

S4SGSN6.

Authentication

/

Security14.

Cancel

Location

Ack19.

Delete

Bearer

ResponseTAU

AcceptTAU

Completenew

Serving

old

Serving

PDN

GWGW

GWTAU

RequestTAU

RequestContext

RequestContext

ResponseeNodeBUEContext

AcknowledgeCreate

Bearer

RequestUpdate

Bearer

Request9a.

PCEF

Initiated

IP-CANSession

ModificationUpdate

Bearer

Response(A)Create

Bearer

ResponseUpda

ocationCancel

LocationUpda ocation

AckDelete

Bearer

Request(B)1.

Trigger

to

startTAU

procedureRNCIu

Release

CommandIu

Release

CompletePCRFLTE->2G3G网络重选流程（S4

SGSN）(A)Modify

Bearer

ResponseUpda

ocation4.

Context

Response5.

Authentication13.

Cancel

Location13.

Cancel

Location

Ack6.

Context

AcknowledgeUE

eNodeBRNC/BSS

SGSNMMEServingGWPDNGWHSS10.

Modify

Bearer

Response1.

UE

Changes

toUTRAN

ERAN2a.

Routeing

Area

Update

Request2b.

Routeing

Area

Update

Request3.

Context

Request14.

S1-AP:

S1

Release

CommandRelease

E-UTRANconnection14.

S1-AP:

S1

Release

CompletePCRF15.

Upda

ocation

AckRouteing

Area

Update

AcceptRouteing

Area

Update

CompleteService

RequestRAB

Assignment

Request21b.

RAB

Assignment

ResponseModify

Bearer

Request22b.

Modify

Bearer

ResponseModify

Bearer

RequestModify

Bearer

RequestPCEF

Initiated

IP-CANSession

ModificationLTE->2G3Ghandover流程（S4

SGSN）准备阶段UESourceeNodeBRNCSource

MMESGSN Serving

GWHSS1.

Handover

Initiation2.

Handover

Required3.

Forward

Relocation

RequestPDN

GWUplink

and

Downlink

User

Plane

PDUsServing

GWCreate

PDP

ContextRequest

4a.

Create

PDP

Context

ResponseRelocation

Request5a.

Relocation

Request

AcknowledgeCreate

PDP

ContextRequest6a.

Create

PDP

Context

ResponseForward

RelocationResponseCreate

Bearer

Request

8a.CreateBea

erResponseLTE->2G3Ghandover流程（S4

SGSN）执行阶段UESourceeNodeBPDN

GW

HSSRNC

Source

MME

SGSN

Serving

GWUplink

and

Dow

nlink

User

Plane

PDUsHandover

Comm

andHO

from

-E-UTRAN

Comm

andSending

ofuplink

datapossible6.

Forward

Relocation

Complete8a.

Update

Bearer

Response4.

UTRAN

IuAccess

Procedures4a.

Handover

to

UTRAN

Co

mpleteDownlink

User

Plane

PDUsOnly

if

Indirect

Forwarding

isapplicable.

For

"Indirect

Forw

arding",

Serving

GWForw

arding"

and

Serving

GWrelocation

the

PDUs

w

ill

beforwarded

by

the

source

ServingGW

tothen

toServing

GW

andRNC

w

hen

DirectTunnel

is

used,

SGSN6a.

Forward

Relocation

Complete

Acknowledge

when

Direct

Tunnel

is

not

used.7.

Update

PDP

Context

RequestServing

GW(A)8.

Update

Bearer

RequestOnly

if

Direct

ForwardingisapplicableVia

SGSN

in

case

Direct

Tunnel

is

not

used5.

Relocation

CompleteUpdate

PDP

Context

ResponseUplink

and

Dow

nlink

User

Plane

PDUs

(Via

SGSN

in

case

Direct

Tunnel

is

not

used)Routing

Area

Update

procedureDelete

Bearer

Request(B)11a.

Delete

Bearer

Response11b.

Release

ResourcesIn

case

of

Serving

GW

relocation

Step

7,

8and

9,

and

the

follow

ing

User

Plane

path,will

be

handled

by

Serving

GW2G3G->LTE

handover流程（S4

SGSN）准备阶段UESourceRNCeNodeBSource

SGSNMMEServing

GWHSS1.

Handover

Initiation2.

RelocationRequired3.

Forward

RelocationRequestPDNGWUplink

and

Downlink

User

Plane

PDUs

(via

Source

SGSNin

case

Direct

Tunnel

isnot

used)Serving

GWCreate

BearerRequest4a.

Create

BearerResponseHandover

Request5a.

Handover

Request

AcknowledgeCreate

BearerRequest6a.

Create

BearerResponseForward

Relocation

ResponseCreate

Bearer

Request

8a.

Create

BearerResponse2G3G->LTE

handover流程（S4

SGSN）执行阶段UESourceeNodeBPDN

GW

HSSRNC

Source

MME

SGSN

Serving

GWUplink

and

Dow

nlink

User

Plane

PDUsHandover

Comm

andHO

from

-E-UTRAN

Comm

andSending

ofuplink

datapossible6.

Forward

Relocation

Complete8a.

Update

Bearer

Response4.

UTRAN

IuAccess

Procedures4a.

Handover

to

UTRAN

Co

mpleteDownlink

User

Plane

PDUsOnly

if

Indirect

Forwarding

isapplicable.

For

"Indirect

Forw

arding",

Serving

GWForw

arding"

and

Serving

GWrelocation

the

PDUs

w

ill

beforwarded

by

the

source

ServingGW

tothen

toServing

GW

andRNC

w

hen

DirectTunnel

is

used,

SGSN6a.

Forward

Relocation

Complete

Acknowledge

when

Direct

Tunnel

is

not

used.7.

Update

PDP

Context

RequestServing

GW(A)8.

Update

Bearer

RequestOnly

if

Direct

ForwardingisapplicableVia

SGSN

in

case

Direct

Tunnel

is

not

used5.

Relocation

CompleteUpdate

PDP

Context

ResponseUplink

and

Dow

nlink

User

Plane

PDUs

(Via

SGSN

in

case

Direct

Tunnel

is

not

used)Routing

Area

Update

procedureDelete

Bearer

Request(B)11a.

Delete

Bearer

Response11b.

Release

ResourcesIn

case

of

Serving

GW

relocation

Step

7,

8and

9,

and

the

follow

ing

User

Plane

path,will

be

handled

by

Serving

GW内容EPC与2G3G互操作概述EPC与2G3G互操作流程EPC与2G3G互操作EPC网络部署默认承载和 承载默认承载－－－类似一次激活一个 有效的承载，该承载在用户attach时建立。C规则使用PCRF下发的或P-GW上配置APN使用的是HSS中签约的默认AP的默认规则，地址由P-GW分配。一定是非GBR（Guaranteed

Bearer

Rate）承载一般是低带宽、低时延、可用于

DHCP服务器、IMS

等。承载－－－类似二次激活在默认承载建立后根据用户或应用层需要而建立，可以由网络侧或MS发起。在默认承载基础上建立的到同一PDN的不同QoS的承载。可以是GBR或非GBR承载多PGW问题－－－类似激活第二个PDP当UE需要接入一个新PDN的时候，UE将新的APN带给MME，MME可能重新选择一个新的PDN

G

S系统支持一个PDN

GW接入多个PDN，也支持多个PDN

GW分别接入多个PDN。ISR

(Idle

Signaling

Reduction)——移动管理优化TA1TA3RA3TA2TA4TA5RA1RA2TA

List1TA

List2ISRCombinedArea=

TA

List+RA在联合区域内用户无需触发TA更新ISR

is

not mended

to

deploy

in

commercialphase

because

of

its

complexity

and

less

benefits.联合区域RA4EPS与2/3G

QOS比较2G/3G网络支持网络和UE对QoS的协商，EPS中QoS不支持协商，控制全部在网络实现，如果部署PCC则由PCRF控制，否则在P-GW静态配置QoS策略。EPS和2G/3G的QoS

Profile中包含的参数不同。EPS的QoS

Profile中的参数包括：UE的QoS参数UE-AMBR和APN-AMBR，以及承载层的QoS参数QCI,

ARP,

GBR

and

MBR。2G/3G网络的QoS

Profile中的参数都是基于承载级别的，包括Traffic

class,MBR,

GBR,

ARP等QOSQCITrafficClassTrafficHandlingPrioritySignalingIndicationSource

StatisticsDescriptor1ConversationalN/AN/ASpeech2ConversationalN/AN/AUnknown3StreamingN/AN/ASpeech4StreamingN/AN/AUnknown5Interactive1YesN/A6Interactive1NoN/A7Interactive2NoN/A8Interactive3NoN/A9BackgroundN/AN/AN/AIPv4v6双栈（Dual

Stack）EPS承载处理IPv4v6承载的优势承载类型LTE2/3G备注IPv4YYUE获取IPv4地址转发IPv4报文Ipv6YYUE获取IPv6地址转发IPv6报文IPv4v6YY/NUE获取IPv4和v6地址和转发IPv4和v6报文解决在1个PDP上下文中传送IPv4和IPv6地址的用户数据，减少了需要的承载上下文数量根据终端的能力在请求建立的承载类型具备IPv6和IPv4

能力请求IPv4v6IPv4终端请求IPv4IPv6终端请求IPv6终端能力不明，请求IPv4v6SGSN/MMEPDN-GWMME/SGSN根据如下条件，向

PGW请求标示Dual

Stack

FlagPGW检查如下条件，判断是否接受Dual

Stack请求UE是否签约Dual

Stack，否则 ，否则返回给UE“subscription

limitation”UE是否可能切换到不支持

IPv4v6网络，是则返回给UE“single

address

bearers

only”若不允许该APN使用两个IP地址，则只分配一个IP地址，并返回给UE

“networkpreference”如果允许该APN使用两个IP地址，则分配IPv4地址和

IPv6地址，接受请求R8网络IPv4v6双栈承载的处理方式终端LTE与2/3G承载之间要求一对一GGSN与PGW的选择策略根据APN选择PGWSGSN根据终端网络能力进行区分选择GGSN和PGWSGiGnGnS1-MMEPCRFGxHSSS10UEGERANUTRANGn/GpSGSNE-UTRANMMES11S5SGWPGWOp