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Introduction to the
www.huawei.com
Introduction to the VoLTE Solution
Copyright © 2014 Huawei Technologies Co., Ltd. All rights reserved.
Reference
� VoLTE Product Documentation
Copyright © 2014 Huawei Technologies Co., Ltd. All rights reserved. Page1
Objectives
� Upon completion of this course, you will be able to
understand:understand:
� VoLTE solution basic concepts
� VoLTE solution architecture
� VoLTE evolution trend
Huawei VoLTE solution products and deployment principles
Copyright © 2014 Huawei Technologies Co., Ltd. All rights reserved.
� Huawei VoLTE solution products and deployment principles
Page2
Contents
1. VoLTE Solution Basic Concepts
2. VoLTE Network Evolution2. VoLTE Network Evolution
3. Huawei VoLTE Solution Architecture
4. Huawei VoLTE Solution Products
Copyright © 2014 Huawei Technologies Co., Ltd. All rights reserved. Page3
Contents
1. VoLTE Solution Basic Concepts
1.1 Commercial LTE Voice Solutions1.1 Commercial LTE Voice Solutions
1.2 Advantages of VoLTE
1.3 Key Technologies Involved in VoLTE
Copyright © 2014 Huawei Technologies Co., Ltd. All rights reserved. Page4
Commercial LTE Voice Solutions
Copyright © 2014 Huawei Technologies Co., Ltd. All rights reserved. Page5
CSFB Definition� The circuit switched fallback (CSFB) service enables calls to fall back to the CS
domain. The LTE network provides only data services. When a voice call is initiated or answered, it falls back to the CS domain for processing. Therefore, carriers only need to upgrade the MSC server without deploying the IMS network.carriers only need to upgrade the MSC server without deploying the IMS network.
� Advantage: Voice services can be provided quickly with little change on the live network.
� Disadvantage: When subscribers use voice services, data services carried on the LTE network are interrupted, handed over, or suspended, and voice calls are connected slowly. This affects user experience.
� Application scenario:
CSFB is a transition solution before the IMS network deployment.
Copyright © 2014 Huawei Technologies Co., Ltd. All rights reserved.
� CSFB is a transition solution before the IMS network deployment.
� If the IMS network is not deployed on the visited network, CSFB can provide voice services for roaming LTE subscribers.
Page6
CSFB Definition (Cont.)
MME
SGs
MSC server
CS EPC
� Terminating side� The MSC server sends a paging request to
the MME over the SGs interface.� The MME forwards the paging request
instructing the UE to fall back to the 2G or 3G network.
� Originating side
The UE sends a voice call request to the
LTE2G/3G
MMEMSC server
CS EPC
Fallback
3
SGs
1
3G network.� The UE falls back to the 2G or 3G network.� The UE sends a paging response to the
MSC server and answers the call based on the normal terminating flow.
1
2
� The UE sends a voice call request to the
MME. The MME then instructs the UE to
fall back to the 2G or 3G network.
� The UE falls back to the 2G or 3G network.
� The UE initiates a call based on the normal
originating flow on the 2G or 3G network.
LTE2G/3G
4 2
Fallback3
Page7
SVLTE Definition� In the simultaneous voice and LTE (SVLTE) solution, dual-mode mobile phones
work on the LTE network and the CS network simultaneously. The LTE network provides data services, while the CS network provides voice services.
� Advantage: SVLTE is a solution for mobile phones without requirements for the network.network.
� Disadvantage: The cost and power consumption of dual-mode mobile phones are high.
CS EPC
MSC serverMME
Copyright © 2014 Huawei Technologies Co., Ltd. All rights reserved.
LTE2G/3G
Data serviceVoice service
Page8
OTT Definition
� Over-the-top (OTT) is a solution that uses APPs, such as the Skype, to
provide voice services for LTE subscribers.
� Advantage:
� Only the OTT server needs to be deployed to the live network and slight change is
required. The OTT can enhance user experience by offering rich multimedia
services.
� Disadvantages:
� The OTT solution is not carrier-class-based and has low reliability.
Copyright © 2014 Huawei Technologies Co., Ltd. All rights reserved.
� The OTT solution cannot provide E2E QoS guarantee.
� The OTT solution is hard to provide common services, such as emergency calls
and interception, and services that are used only by regulatory bodies.
� Roaming and interconnection are hard to be implemented due to lack of standards.
Page9
Contents
1. VoLTE Solution Basic Concepts
1.1 Commercial LTE Voice Solutions1.1 Commercial LTE Voice Solutions
1.2 Advantages of VoLTE
1.3 Key Technologies Involved in VoLTE
Copyright © 2014 Huawei Technologies Co., Ltd. All rights reserved. Page10
VoLTE DefinitionVoice over long term evolution (VoLTE) is an IMS-ba sed voice solution defined by 3GPP. By deploying the IMS network, operators no t only migrate traditional voice and short message services on live networks b ut also integrate voice services with various enhanced functions to diversi fy services.
VoLTE advantages
� The VoLTE solution inherits all services provided by the CS network, including common services, such as emergency calls and interception, and services that are used only by regulatory bodies.
� The VoLTE solution can implement E2E QoS control and guarantee voice call quality.
� In the VoLTE solution, voice services are carried on IP networks. Therefore, subscribers can enjoy richer multimedia services through the IMS network, compete with OTT.
Copyright © 2014 Huawei Technologies Co., Ltd. All rights reserved.
enjoy richer multimedia services through the IMS network, compete with OTT.
� Subscriber identities (such as the MSISDN) are reserved, which maximizes carriers' resource usage and facilitates service profit gain.
� The IMS architecture, supported by mature 3GPP standards and specifications, is considered to be the next generation core network by the communications industry. The IMS architecture ensures roaming services and network interworking.
Page11
Advantage of VoLTE – Better and Faster
Faster connection rate
Better communication
quality
Higher spectral
efficiency
Richer services
� VoLTE can significantly reduce the call establish de lay, provide high-
� Fast connection:
� CS call establish duration is around 4-5s,
VoLTE is 0.8 -1.5s.
� HD video:
� VoLTE typical video definition is 480*640
definition audio and video calls, greatly enhance t he user experience
Copyright © 2014 Huawei Technologies Co., Ltd. All rights reserved.
SD and HD video size compare
� VoLTE typical video definition is 480*640
(VGA), HD 720P and full HD 1080P is
possible(H.264/H.265)
� 3G typical video definition is 176*144
(QCIF)
Advantage of VoLTE -- HD Voice Quality
Common ear listening range (CD/MP3 range)
The frequency range of human speechHD voice (AMR-WB)
20 Hz
20k Hz50 Hz
80 Hz
12k Hz7000 Hz
HD voice (AMR-WB)
300Hz
3400Hz
CS(AMR-NB)
Audio range
Copyright © 2014 Huawei Technologies Co., Ltd. All rights reserved.
HD voice: (Twice frequency range the AMR-NB)
• VoCS voice: AMR-NB 300~3400 Hz, sampling frequency 8kHz, 12.2Kbps。• VoLTE HD voice: AMR-WB (G.722.2 ) : 50~7000 Hz, same as the G.711 in PSTN, sampling frequency 16kHz, 23.85Kbps. • CD music: 20~20K Hz, sampling frequency 44.1K.
Advantage of VoLTE -- QoS
Best effort for OTT services
Dedicate bearer for VoLTE
LTE
Copyright © 2014 Huawei Technologies Co., Ltd. All rights reserved.
QCI Resource Pri. Delay Error rate service
2 GBR 4 150ms 10 -6 VoLTE video
6 Non-GBR 6 300ms 10-3 OTT video
QCI: QoS class identifier GBR: guaranteed bit rate
Comparison Among CSFB, SVLTE, VoLTE and OTT
Solution Feature Advantage DisadvantageDeployment Suggestion
VoLTE
The IMS and LTE networks provide voice services. The handover between the LTE
Rich multimedia services.HD voice/video.
The IMS network needs to be deployed.
Large-scale LTE coveragebetween the LTE
network and 2G/3G network is supported.
HD voice/video.E2E QoS
needs to be deployed. coverage
OTTVoice services are implemented by APPs of OTT carriers.
Slight change is required on live networks.
Voice calls are not reliable.Roaming and interworking are hard to be implemented.
-
CSFB
UEs attach to the LTE network. When a UE initiates or receives a call, the UE falls back to
Slight change is required on live networks.New NEs do not need
The call delay is long.User experience is affected.
Initial phase of the LTE network (transition
Copyright © 2014 Huawei Technologies Co., Ltd. All rights reserved.
call, the UE falls back to the CS network.
New NEs do not need to be deployed.
affected.(transition solution)
SVLTE
Terminals attach to both the CS and LTE networks. The CS network provides voice services.
The live network does not need to be adjusted.
Costs of mobile phones are high. Advantages of the LTE network cannot be used.
Initial phase of the LTE network (transition solution)
Page15
Contents
1. VoLTE Solution Basic Concepts
1.1 Commercial LTE Voice Solutions1.1 Commercial LTE Voice Solutions
1.2 Advantages of VoLTE
1.3 Key Technologies Involved in VoLTE
Copyright © 2014 Huawei Technologies Co., Ltd. All rights reserved. Page16
Key Technologies Involved in VoLTE
� Voice based on IMS
� VoLTE voice services are IMS-based.� VoLTE voice services are IMS-based.
� SRVCC/eSRVCC
� If VoLTE voice services need to be handed over the GSM or
RAN network, SRVCC or eSRVCC is used.
� ICS for VoLTE
Copyright © 2014 Huawei Technologies Co., Ltd. All rights reserved.
� ICS for VoLTE
� To ensure that subscribers have consistent user experiences
on the LTE and CS networks, ICS is used.
Page17
IMS-based Voice Services
� A default bearer is set up for IMS signaling streams when the UE attaches to the network.
� After the UE initiates a call, SIP signaling streams for call connection is transmitted over the
default bearer through the P-GW to the IMS Core.
Copyright © 2014 Huawei Technologies Co., Ltd. All rights reserved.
default bearer through the P-GW to the IMS Core.
� A dedicated bearer for IMS voice media streams is set up during call connection.
� Voice media streams of the calling and called parties are transmitted over the dedicated bearer.
� The PCRF assigns and delivers QoS rules for signaling and media streams during the setup of
default and dedicated bearers. This ensures quality of signaling and media streams.
Page18
SRVCC Definition
� Single radio voice call continuity (SRVCC) is an IMS-based VoLTE.
� VCC describes how a voice call can be continued when a UE moves
between the target CS domain and the LTE domain supporting VoIP
services.
� SRVCC describes how a voice call can be continued when a Single
Radio UE moves between LTE/Pre-LTE and 2G/3G networks, that is,
when a Single Radio UE switches an call session between IMS/LTE and
CS.
Copyright © 2014 Huawei Technologies Co., Ltd. All rights reserved. Page19
SRVCC Definition (Cont.)� Calls are set up in the LTE over VoIP / VoIMS.
� When a subscriber moves to an area uncovered by the LTE network while holding
a call, the call is switched to the CS domain. SRVCC interprets a switchover
process.
� SRVCC solution: The media
handover point is a peer
device. Such as a peer UE.
� E2E signaling and bearer are
re-established.
Copyright © 2014 Huawei Technologies Co., Ltd. All rights reserved. Page20
� The IMS network sends the
updated media information to
the remote network, and a
session is interrupted around
1s.
eSRVCC Definition� Target: The handover delay is less than 300 ms
� Policy: The remote session update process is optimized. The media handover point is near to the local side .
Method: Media and signaling � Method: Media and signaling planes are anchored at the ATCF or ATGW to avoid the IMS session transfer process. When an eSRVCC handover is performed, only the bearer between the UE and the ATGW needs to be set up.
Copyright © 2014 Huawei Technologies Co., Ltd. All rights reserved.
� The original bearer is reused to transmit media streams between the peer device and the ATGW.
Page21
eSRVCC Vs SRVCCbefore
afterSRVCC
E2E media re-establish
LTE RANIMS/SBC
eSRVCCLocal media establish
LTE RAN
IMS/SBC
(ATCF & RAN
G/U RAN
IMS/SBC
> 1.5s
Remote side
RAN
G/U RAN
(ATCF & ATGW)
~ 0s
Remote side
< 230ms
Copyright © 2014 Huawei Technologies Co., Ltd. All rights reserved.
First eSRVCC testing (Vienna 201210)
1.5s 0s 230ms
LTE to GSM HO time ~ 230ms (Beijing 201404)
ICS Definition
� IMS centralized services (ICS) describe how services of subscribers who access the CS domain or IP-CAN using different terminals are managed on the IMS network in centralized mode.on the IMS network in centralized mode.
� With the ICS feature, all services are centralized to IMS. Therefore, subscribers can have consistent user experiences on the LTE and CS networks.
� By deploying an MSC server that supports the ICS feature on a network, ICS subscribers can use services provided by IMS during the initial phase of LTE in the following scenarios:
Copyright © 2014 Huawei Technologies Co., Ltd. All rights reserved.
� CS subscribers who have subscribed to the ICS feature wish to use IMS services without changing their numbers.
� VoLTE subscribers who roam to or experience an SRVCC handover to a CS network wish to continue to use the IMS services.
Page23
ICS Definition (Cont.)� The ICS solution becomes the
best choice for evolution from the mobile softswitch to IMS. The eMSC server functions as
ASAS ASService layer
Centralized service
ICS Architecture
The eMSC server functions as a SIP UA and connects subscribers to the IMS Core.
� MSC server enhancements for ICS, the MSC server that supports the ICS feature, is called mobile access gateway control function (mAGCF). In
IMS Core
MGW
mAGCFMSC server
Centralized service trigger point
Access layer
xPON and FBB
Copyright © 2014 Huawei Technologies Co., Ltd. All rights reserved.
control function (mAGCF). In this document, the MSC server enhancements for ICS is called eMSC server.
MGW
LTE2G/3G
LTE subscriberCS subscriber
Page24
Contents
1. VoLTE Solution Basic Concepts
2. VoLTE Network Evolution2. VoLTE Network Evolution
3. Huawei VoLTE Solution Architecture
4. Huawei VoLTE Solution Products
Copyright © 2014 Huawei Technologies Co., Ltd. All rights reserved. Page25
Contents
3. Huawei VoLTE Solution Architecture
3.1 VoLTE Layered Network Architecture 3.1 VoLTE Layered Network Architecture
3.2 VoLTE Key NE Functions
3.3 VoLTE Interface and Protocol
Copyright © 2014 Huawei Technologies Co., Ltd. All rights reserved. Page26
VoLTE Network Architecture
Operation Support Layer and Service Layer
Operation support layer
� Operation support layer� Functions: This layer provides various
functions, such as network management, subscription data storage, unified operations on subscription data storage, unified operations on the web portal, charging, and equipment management.
� NEs: DMS, SPG, CCF, and EMS
Service layer� Service layer� Functions: This layer consists of different
application servers and resource servers to ATS
Copyright © 2014 Huawei Technologies Co., Ltd. All rights reserved.
application servers and resource servers to provide services, such as instant messaging, conferences, games, as well as service capabilities, such as group and media resource capabilities.
� NEs: ATS and RCS
ATS(MMtel AS/SCC AS/IP-SM-GW/IM-SSF/Anchor AS)
Page28
Core Layer
Core layer� The core layer is divided into the following
three parts:� IMS domain: NEs in the IMS domain
implement such functions for LTE subscribers implement such functions for LTE subscribers as registration, authentication, session path control, service trigger, route selection, resource control, inter-domain interworking, and access resource control.
� CS domain: NEs in the CS domain implement
such functions for LTE subscribers as mobility management and voice services, including handovers and CSFB.
� SingleSDB: The SingleSDB provides the
Copyright © 2014 Huawei Technologies Co., Ltd. All rights reserved.
� SingleSDB: The SingleSDB provides the
functions of the USCDB, HLR, IMS-HSS, SAE-HSS, PCRF, DNS/ENUM for centralized storage of VoLTE subscribers' service data. The data can be used by the CS, IMS, and EPC domains.
Page29
Access Layer
Access layer� Access layer� Functions:� The access layer controls LTE subscriber
access and provides mobility management for
LTE subscribers.
� When an LTE subscriber is in the LTE
coverage, the subscriber can access an IMS
network through the EPC.
� When a subscriber moves out of the LTE
coverage, the subscriber can access an IMS
network through a 2G/3G network using ICS.
Copyright © 2014 Huawei Technologies Co., Ltd. All rights reserved.
� If the 2G/3G network does not support ICS, a
subscriber accesses a legacy CS network.
� NEs: eMSC server (mAGCF), S-GW, P-GW, and
MME
Page30
Terminal Layer
Terminal layer� Terminal layer� LTE terminals are classified into VoLTE
terminals and non-VoLTE terminals.� VoLTE terminals are those that rely on an
IMS or LTE network to use voice services.
They include Single Radio terminals, LTE
data cards, and CPEs.
� Non-VoLTE terminals are those that rely on
a CS network to use voice services and that
connect to an LTE network to use data
services. They include Dual Radio and
Copyright © 2014 Huawei Technologies Co., Ltd. All rights reserved.
CSFB terminals.
� Types: Single Radio terminals (SRVCC
terminals), LTE data cards, CPEs, Dual Radio
terminals (SVLTE terminals), and CSFB
terminals
Page31
Contents
3. Huawei VoLTE Solution Architecture
3.1 VoLTE Layered Network Architecture 3.1 VoLTE Layered Network Architecture
3.2 VoLTE Key NE Functions
3.3 VoLTE Interface and Protocol
Copyright © 2014 Huawei Technologies Co., Ltd. All rights reserved. Page32
NEs at the Operation Support LayerNE Name Function
SPGProvides a unified service provisioning interface and the web portal and sends the service provisioning commands received from the SPG and sends the service provisioning commands received from the BSS to the HSS, ENUM, and AS.
CCFCollects ACR messages from IMS charging NEs, such as the CSCF, ATS, and MGCF, processes the ARC messages to generate CDRs, and sends the CDRs to a BC specified by carriers.
EMS Interworks with the BSS to manage NEs in a centralized manner.
Copyright © 2014 Huawei Technologies Co., Ltd. All rights reserved.
EMS Interworks with the BSS to manage NEs in a centralized manner.
Page33
NEs at the Service LayerNE Name Function
� MMTel AS: provides basic and supplementary multimedia telephony services.
� SCC AS: interworks with the SRVCC IWF and ATCF/ATGW to provide the eSRVCC function, and provides the T-ADS function
Common telephony application server (ATS)
provide the eSRVCC function, and provides the T-ADS function to select a domain for the called party.
� IP-SM-GW: provides short message interworking between IMS and CS domains.
� IM-SSF: triggers IN services in the CS domain based on the subscription information provided by the S-CSCF and the local configuration on the IM-SSF.
• Anchor AS: Routes VoLTE subscribers' calls to the IMS domain to trigger convergent services by IN-based number redirection of the anchor AS, when the VoLTE subscribers
Copyright © 2014 Huawei Technologies Co., Ltd. All rights reserved.
redirection of the anchor AS, when the VoLTE subscribers originate or receive a call in the CS domain.
RCS AS
Provides the Open Mobile Alliance Instant Message (OMA IM), Presence, XML document management server (XDMS), and data synchronization (DS) functions to implement the IM, Presence, and Network Address Book services.
Page34
NEs at the Service Layer - ATS
� The ATS provides
traditional mobile services
and multimedia services.
Business service
Mobile special service
TISPAN PSTN service
3GPP MMTel service
and multimedia services.
IMS network
Mobile terminal
Soft phone
SIP terminalCPE
MBB FBB PSTN
ATS(MMTel + SCC AS + IP-SM-GW
+ IM-SSF + anchor AS)
Copyright © 2014 Huawei Technologies Co., Ltd. All rights reserved.
terminal phone terminalCPE
POTS POTS
� The ATS integrates the functions of the MMTel AS, IM-SSF, SCC AS, Anchor AS, and IP-SM-GW to reduce the number of attempts to trigger iFC during calls and realize service resources sharing.
Page35
NEs at the Service Layer - SCC AS (ATS)
� The service centralization and continuity application server (SCC AS) implements handovers in the IMS domain and updates the media information about the
ISC
SCC AS
domain and updates the media information about the remote UE. In details, the SCC AS does the following:
EPCCS
IMS Core
eMSC server(SRVCC IWF)
LTE
SCC ASCalling
Called connection 3
Media connection 1Call signaling anchor point
� Analyzes information required by a handover.
� Associates handover requests and anchors sessions.
� Implements handovers
Copyright © 2014 Huawei Technologies Co., Ltd. All rights reserved.
GERANUMTS
Called party access
SCC ASCalling
connection 1
Calling connection 2
Called connection 3
Media connection 2
Handover� Implements handovers between the LTE network and the UMTS network.
Page36
NEs at the Service Layer - T-ADS (SCC AS)� T-ADS
� As defined in 3GPP specifications, domain selection by the network is
implemented by the terminating access domain selection (T-ADS).
� The T-ADS function is integrated with the SCC AS. The SCC AS queries the
convergent HLR/HSS for the UE type and access domain information and
implements domain selection based on the carrier policies. Based on the T-
ADS information, the SCC AS determines whether the current call is routed to
the IMS or CS network.
Copyright © 2014 Huawei Technologies Co., Ltd. All rights reserved. Page37
NEs at the Service Layer - IP-SM-GW (ATS)� The IP short message gateway (IP-SM-
GW) provides short message interworking between IMS and CS
OCS CGF/CDF
Ro Rfinterworking between IMS and CS domains.
IMS Core
ISC
IP-SM-GW
UE
HSS•SMS-GMSC/•SMS-IWMSC
SMSC
SME
Ro Rf
Sh
E/Gd
1 SIP message
2 Translates instant messages to short messages.
3 Sends short messages to UEs.
Copyright © 2014 Huawei Technologies Co., Ltd. All rights reserved.
UESME
� After the UE sends a SIP message, the IP-SM-GW converts the instant message (SIP message) to a text message. When the UE registers with IMS, the IP-SM-GW downloads the SMSC address to a local directory.
Page38
NEs at the Service Layer - Anchor AS (ATS)
The anchor AS anchors calls from the
CS network to the IMS network as
follows:IMS
Anchor AS
AS
follows:
� Routes VoLTE subscribers' calls to
the IMS domain to trigger convergent
services by IN-based number
redirection of the anchor AS, when
the VoLTE subscribers originate or
receive a call in the CS domain.
� Routes VoLTE subscribers' calls to
CS MSC server
IMSAnchor AS
VoLTE subscriber
Copyright © 2014 Huawei Technologies Co., Ltd. All rights reserved.
� Routes VoLTE subscribers' calls to
the IMS domain by IN-based number
redirection of the anchor AS, when
the VoLTE subscribers receive calls
from CS subscribers.
CS MSC server
LTE
VoLTE subscriber
Page39
NEs at the Core LayerNE Name Function
IMS-HSS (FE)
Controls subscriber roaming and stores the following information about a subscriber in the IMS network: subscriber IDs, authentication data, service data, access parameters, service trigger information, and roaming information.
Stores service-related data of subscribers, manages subscription information and SAE-HSS/HLR (FE)
Stores service-related data of subscribers, manages subscription information and location information, and combines the following NEs:• HSS in the EPC network• HLR in CS and PS domains in the core network of the mobile telecommunication
system
USCDB (BE)
Stores subscriber data and implements the functions of adding, deleting, updating, and querying data at the request of the FE.
DNS/ENUM Implements functions provided by the DNS and the ENUM server.
eMSCserver(SRVCC
Combines the following NEs:• SRVCC IWF: provides eSRVCC to ensure call continuity when terminals move
from an LTE network to a 2G/3G network.
Copyright © 2014 Huawei Technologies Co., Ltd. All rights reserved.
(SRVCC IWF/CSFB proxy)
from an LTE network to a 2G/3G network.• CSFB proxy: moves LTE subscribers to a CS domain to provide voice services for
them.
MGCF
Realizes interworking between an IMS network and a PSTN or PLMN network.If fixed network optimization is required or the live network provides a lot of fixed network services, the UGC3200 is used as the MGCF. In other scenarios, the MSOFTX3000 is used as the MGCF.
Page40
NEs at the Core Layer (Cont.)NE Name Function
MRFPProvides resources for announcement playing and digit collection, voice conferences, SD video conferences.
Combines the following NEs to provide call control, service triggering, and routing functions:
I-CSCF/S-CSCF/BGCF/MRFC
functions:• I-CSCF: As the entrance to the IMS home network, the I-CSCF assigns or queries
the HSS to select an appropriate S-CSCF to serve subscribers.• S-CSCF: The S-CSCF is located on the home network as the central IMS node. It
implements subscription, authentication, session, routes, and service triggering.• BGCF: The BGCF is located on the home network to select an MGCF for calls
between an IMS network and a PSTN or PLMN network. It is integrated into the S-CSCF to reduce the need for standalone BGCFs. Therefore, call connection delay is shorten and the reliability is enhanced.
• MRFC: The MRFC controls the MRFP to play announcements and collect digits, and provide resources for voice conferences and SD video conferences.
Copyright © 2014 Huawei Technologies Co., Ltd. All rights reserved.
and provide resources for voice conferences and SD video conferences.
Page41
NEs at the Core Layer (Cont.)NE Name Function
• P-CSCF: located on the visited network as the first contact point for subscribers within an IMS domain. The P-CSCF forwards SIP signaling between SIP subscribers and their home networks.
P-CSCF/SBC/ATCF/ATGW
between SIP subscribers and their home networks.• SBC: provides the core border gateway function (C-BGF) and interconnection
border gateway function (I-BGF). The C-BGF is deployed at the edge of an access network to provide attack protection and NAT traversal. The I-BGF provides media channels for an IMS network to interwork with other networks that use SIP or H.323 signaling.
• ATCF/ATGW: located between the P-CSCF and I-CSCF/S-CSCF and interworks with the SCC AS to provide eSRVCC.
MGW/IM-MGWProvides audio media channels for interworking between an IMS network and a PSTN or PLMN network.
Copyright © 2014 Huawei Technologies Co., Ltd. All rights reserved.
PSTN or PLMN network.
Page42
NEs at the Core Layer - SRVCC IWF
SCC AS
� The SRVCC IWF ensures call continuity when terminals move from an LTE network to a 2G/3G network. When receiving the location update request from a UE, the SRVCC IWF changes the UE access location from the MME to the MSC server based on the target cell ID
� The SRVCC IWF is collocated with an MSC server or deployed as a standalone entity. If the SRVCC IWF is deployed as a standalone entity, it functions as a proxy of the
EPCCS
IMS Core
SveMSC server(SRVCC IWF)
MSC Selects target MSC2
contained in the location update request.
Copyright © 2014 Huawei Technologies Co., Ltd. All rights reserved.
functions as a proxy of the MSC server and performs conversion for signaling messages between the MSC server, SBC, and MME.
MME
MSC
UESRVCC IWF
Handover request
MSC
MSC
MSC1
Page43
NEs at the Core Layer - ATCF/ATGW� The ATCF/ATGW is located between the P-CSCF and I-CSCF/S-CSCF
and interworks with the SCC AS to provide eSRVCC.
� During a call, the ATCF or ATGW determines whether to anchor a call on the During a call, the ATCF or ATGW determines whether to anchor a call on the
media plane based on carriers' policies and terminal capabilities.
� During an eSRVCC handover, the ATCF or ATGW correlates a handover
request initiated by the SRVCC IWF with the anchored session, updates
session bearer information, and initiates a handover request to the SCC AS.
CSIMS Core SCC AS
SRVCCIWF
2G/3G
Remote UE
Copyright © 2014 Huawei Technologies Co., Ltd. All rights reserved.
Signaling before a handover
Bearer before a handover
Signaling after a handover
Bearer after a handover
Local handover duration: < 300 ms
PS SBC
Handover
LTEATCF
ATGW
Change is not required.
Page44
NEs at the Access LayerNE Name Function
eMSC server(mAGCF)
Helps ICS subscribers in a CS domain to register with an IMS domain and provides basic and supplementary services for them.
S-GW/P-GW
• S-GW in an EPC domain: serves as an anchor point for the user plane between access networks in 3GPP. The S-GW is used as an interface to screen different access networks in 3GPP.
• P-GW in an EPC domain: serves as an anchor point between a 3GPP access network and non-3GPP access network. It provides an interface for interworking between a 3GPP access network and external PDN.
Copyright © 2014 Huawei Technologies Co., Ltd. All rights reserved.
MMEImplements mobility management for LTE subscribers, including subscriber context and mobility status management, and temporary identity distribution.
Page45
Contents
3. Huawei VoLTE Solution Architecture
3.1 VoLTE Layered Network Architecture 3.1 VoLTE Layered Network Architecture
3.2 VoLTE NE Functions
3.3 VoLTE Interface and Protocol
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Interfaces in the IMS and CS domains and Interworking
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Interfaces for Accessing
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Contents
1. VoLTE Solution Basic Concepts
2. VoLTE Network Evolution2. VoLTE Network Evolution
3. Huawei VoLTE Solution Architecture
4. Huawei VoLTE Solution Products
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Huawei VoLTE Solution
Convergent SDB IMS Core
Presence/IM/DS/XDMSRCS9880
ATS(MMTel AS/SCC AS/IP-SM-GW/Anchor AS/IM
SSF)ATS9900
SCP
Legacy serviceApplication server
EMSiManager
M2000
O&M
Legacy
SBC(P-CSCF/A-BCF/A-BGF/ATCF/ATGW/E-CSCF)
SE2600/SE2900
PCRFUPCC
S-GW/P-GWUGW9811
MMEUSN9810
MRFPMRP6600
MGCFMSOFTX3000
eMSC server(SRVCC-IWF/CSFB proxy)
MSOFTX3000
I-CSCF/S-CSCF/MRFC
CSC3300
CS
EPC
M2000
CCFiCG9815
Provisioning GW
SPG2800
MGWUMG8900
HLR/IMS-HSS/SAE-HSS/ENUM /DNS
IM-MGWUMG8900
DMSTMS9950
Legacynetwork
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UPCCUGW9811USN9810UMG8900
Terminal LTE CPELTE handset LTE data card + software client
LTE2G/3G 2G/3G LTE
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High Integration
SE2600/SE2900
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SE2600/SE2900
Unified Hardware Platform•The IMS domain, evolved packet core (EPC) domain, CS domain, and convergent HLR/HSS of Huawei VoLTE solution run on an ATCA-based Open Standards Telecom Architecture (OSTA) 2.0 platform, which improves hardware integration and simplifies network operation and maintenance.
IMS/MSC server/SingleSDB
EMS/RCS
IMSMSC server
IMS/ATS
UMG8900 P-GW/S-GW/SBC
maintenance.
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MMESingleSDB
Platform: ATCA/ATAE Platform: UMG Platform: PGP
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Unified Network Management
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� The M2000/U2000 is deployed to manage all NEs in IMS, CS, and EPC networks in a unified
manner. The M2000/U2000 functions include monitoring alarms and collecting NE performance
data. With the M2000, operators can monitor, configure, and maintain the entire network
conveniently.
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Solution 2: The Newly Deployed Convergent HSS\HLR Replaces the HLR on the Live Network
� Solution description
� The newly deployed HLR/HSS stores
data of 2G, 3G, 4G subscribers. A data of 2G, 3G, 4G subscribers. A
subscriber from the IMS, PS, and CS
domain can access the data.
Subscriber data stored on the HLR
on the live network is migrated to the
newly deployed convergent
HLR/HSS. Huawei HLR V900R006
or later can be upgraded to the
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convergent HLR/HSS.
� The MSC and SGSN on the live
network update all routes and store
them in the convergent HLR/HSS.
In this solution, only SIM cards need to be changed .
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Solution 3: The Newly Deployed Convergent HSS\HLR Coexists with the HLR, and VoLTE and 2G/3G Subscribers Use the Same Number Segments
� Solution description
� The newly deployed convergent HLR/HSS
manages 4G subscriber data. New VoLTEmanages 4G subscriber data. New VoLTE
subscribers can be defined on the
convergent HLR/HSS. Data of 2G/3G
subscribers who have subscribed to 4G
services is migrated from the HLR to the
convergent HLR/HSS. If 2G/3G subscribers
do not subscribe to 4G services, their data
is still stored in the HLR.
� Routing data for IMSIs and MSISDNs are
configured on the STP and SRF. If
subscribers have subscribed to 4G services,
messages are routed to the convergent
HLR/HSS. If subscribers do not subscribe
to 4G services, messages are routed to the
old HLR.
In this solution, only SIM cards need to be changed .
Summary
� This course describes:
� VoLTE solution basic concepts� VoLTE solution basic concepts
� VoLTE network evolution
� Huawei VoLTE solution architecture and NE functions
� Huawei VoLTE solution products and deployment solutions
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AcronymsVoLTE voice over long term evolutionCSFB circuit switched fallbackSVLTE simultaneous voice and LTEOTT over-the-topCTAS common telecom application serverCTAS common telecom application serverT-ADS terminating access domain selectionEPC evolved packet core MO mobile originatingMT mobile terminatingLTE Long Term EvolutionIMS IP multimedia subsystemSAE system architecture evolutionSMS short message serviceUE user equipment RCS Rich Communication SuiteIM instant message
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IM instant messageICS IMS centralized serviceSRVCC single radio voice call continuityeSRVCC enhanced single radio voice call continuitySCC AS Service Centralization and Continuity Application Server HSS home subscriber server
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Acronyms (Cont.)MME mobility management entityPS packet switchedCS circuit switchedATCF access transfer control functionATGW access transfer gatewayATGW access transfer gatewaymAGCF mobile access gateway control functionAGCF access gateway control functionCSCF call session control functionS-CSCF serving-call session control functionP-CSCF proxy-call session control functionI-CSCF interrogating-call session control functionMRFC multimedia resource function controllerMFFP multimedia resource function processorMGCF media gateway control functionAS application server
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AS application server BGCF breakout gateway control function NAB Network Address BookCAB Convergent Address Book
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