A Seamless Migration from WiMAX to LTE Using the Sonus SIP Core Network

fishecologistMobile - Wireless

Dec 12, 2013 (3 years and 8 months ago)

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A Seamless Migration from WiMAX to
LTE Using the Sonus SIP Core Network
www.sonus.net
Introduction.. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .1
The.Sonus.SIP.Core. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. ..1
Using.the.Sonus.SIP.Core.to.Manage.Services.to.WiMAX.Subscribers. .. .. .. .. ..1
Migrating.the.WiMAX.network.to.an.LTE.network.. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .2
Securing.the.Border.Between.the.SIP.Core.and.the.LTE.Network.. .. .. .. .. .. .. .2
But.I.Thought.You.Needed.an.IMS.Core.to.Deploy.LTE?. .. .. .. .. .. .. .. .. .. .. .. .. .3
Adding.Mobility.to.the.LTE.Network.via.an.IMS.Core.Network.. .. .. .. .. .. .. .. .. .3
Tying.It.All.Together:.Sonus.Global.Services.. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .5
Conclusion. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .5
Table of Contents
Disclaimer and Restrictions
This document is for informational purposes only and is subject to change without notice. Sonus has no obligation to provide any
future releases or upgrades or any of the features, enhancements or functions set forth in this document. Unless specifically
required in a written agreement with Sonus, no product purchased from Sonus is conditioned upon Sonus' development or delivery
of any future release or upgrade or of any feature, enhancement or function. All releases, upgrades, features, enhancements and
functions to be delivered by Sonus are provided on a "when-and-if-available" basis.
Introduction
The widespread adoption of smartphones and tablet devices is changing the way that subscribers see their service providers.
Unlimited voice services no longer command premium pricing, but are viewed as “table stakes” in a broader service offering
that must now include multimedia (voice, data, video) communications with a mobility component. As a result of this shift,
many service providers are adopting a SIP-based, Long Term Evolution (LTE) network strategy to deliver this multimedia
experience to their subscribers. While LTE is today seen as the most viable of the mobile multimedia network architectures, it
has never been the only architecture. As recently as 2008, WiMAX was viewed as a logical, long-term architecture to deliver
IP voice, data and video over wireless networks.
Today, as the industry shifts its attention to LTE and Voice over LTE (VoLTE) networks, early WiMAX adopters are looking
to migrate their network strategy away from the WiMAX model to the more broadly adopted LTE model. Although both
WiMAX and LTE leverage IP/SIP-based core networks, an IP Multimedia Subsystem (IMS) core is often implicit in an LTE
strategy because of its suitability for providing Service Consistency and Continuity (SCC) within the VoLTE sub-model . Yet
the adoption of LTE does not require a similar adoption of VoLTE and, in cases where a service provider plans to continue
offering fixed-only voice services through their existing Voice over Broadband (VoBB) model, there is no requirement to
migrate from the existing VoBB core to an IMS core.
This whitepaper seeks to explain how a service provider can migrate from a WiMAX network to an LTE network in a seamless,
secure and cost-efficient manner. Specifically, this paper reveals how a SIP core network from Sonus Networks can enable
such a migration by allowing service providers to leverage the same core network elements whether deploying a WiMAX, LTE
or VoLTE network.
The.Sonus.SIP.Core
For more than a decade, Sonus Networks has built and deployed SIP core networks for many of the world’s leading service
providers. The key network elements of the Sonus SIP core solution are proven in some of the most demanding voice networks
and include the GSX9000

High-Density Media Gateway, SBC 9000

Session Border Controller, PSX

Centralized Routing
and Policy Server, SGX Signaling Gateway and ASX

Feature Server. For the purposes of our case study, we’ll assume that
Company A has a SIP core configuration that includes the following Sonus and Sonus Partner elements:
>
Sonus SBC 9000 Session Border Controller (SBC) for connectivity to the PSTN and secure connectivity to the IP cloud
>
Sonus PSX Server for centralized session routing and policy management
>
Sonus SGX2000

signaling gateway for SS7 connectivity with the PSTN
>
Sonus ASX server (including the ADS subscriber database server) for the management and delivery of essential Class 5
features including call waiting, call forwarding, etc.
>
Sonus Element Management System and DataStream Integrator for centralized network management and billing
mediation, respectively
>
Sonus Insight Customer Portal (ICP) for web-based subscriber provisioning of call features/services
>
Foundry switching equipment for the interconnection of VoIP core elements
>
Iperia Voicemail VX servers
>
Radisys Convedia media server for various services (IP-PBX, IVR, contact center, etc.)
Using.the.Sonus.SIP.Core.to.Manage.Services.to.WiMAX.Subscribers
In our example, Company A has already deployed a remote WiMAX network for the purpose of delivering wireless broadband
access that includes VoBB service to fixed (but not mobile) phones. Subscribers within the WiMAX network receive their voice
services through a non-IMS SIP client based on the RFC 3261 SIP specification. Mobile phone services are made available to
these subscribers on a separate GSM network that partners with Company A. For their part, Company A does not provide any
mobile voices services through its own network and has no immediate plans to do so, instead adopting the model of a Mobile
Virtual Network Operator (MVNO).
The WiMAX network is connected to the Sonus SIP core network via a third-party Access Service Network (ASN) Gateway as
depicted in the following illustration:
The WiMAX network currently provides wireless broadband data access and both residential and business voice services to
fi xed, SIP-based phones. A key criterion of the Sonus SIP core is the ability to maintain service consistency between the two
networks. That is, subscribers on the WiMAX network must share the same voice service experience as the VoIP and PSTN
subscribers who access the SIP core directly for services. This is achieved in the above example by hosting all subscribers
and services on two geographically distinct (but centrally managed) Sonus ASX/ADS servers.
Migrating.the.WiMAX.network.to.an.LTE.network
In its migration from WiMAX to LTE, Company A will need to preserve the same VoBB services for both sets of subscribers.
During this migration, Company A has the option of connecting ASX/ADS-1 to their existing WiMAX network and ASX/ADS-2
to the LTE network they’re building (see fi gure 2). Such a scenario gives Company A two alternative migration paths:
1.
Build an LTE network in the background and, when it’s ready for deployment, turn off the WiMAX network and turn on the
new LTE network
2.
Deploy the LTE network and gradually migrate WiMAX subscribers to the LTE environment, keeping both networks
operational in parallel for a period of time.
SIP
SIP
WiMAX
BTS
ASN Gateway
SIP
DSI-1
ADS-1
ASX-1
ASX-2
PSX
PSX
Slave
PSX
Slave
SIP
SIP
D+
D+
D+
PSTN
SIP
SGX2K
EMS
Media Server
ICP
Hybrid
Trunking
DSI-2
ADS-2
Sonus
VoIP Core
IP Cloud
TDM Cloud
Figure 1 – Sonus SIP core
network connected to a
remote WiMAX network
SIP
SIP
SIP
WiMAX
BTS
E-UTRAN
ASN Gateway
SIP
SIP
WiMax to
LTE Migration
SG GW PDN GW
MME
HSS
DSI-1
ADS-1
ASX-1
ASX-2
PSX
PSX
Slave
PSX
Slave
SIP
SIP
D+
D+
D+
PSTN
SIP
SGX2K
EMS
Media Server
ICP
Hybrid
Trunking
DSI-2
ADS-2
Sonus
VoIP Core
IP Cloud
TDM Cloud
EPC
Figure 2 – WiMAX to LTE Migration with Service Consistency via Sonus ASX
Securing.the.Border.Between.the.SIP.Core.and.the.LTE.Network
Although the ASX Feature Server is a highly scalable and robust platform designed to support millions of subscribers, it is
not designed to function as a border security or session management device. In order to provide load balancing and protect
the SIP core network from Denial of Service (DoS) attacks and other security threats, Sonus recommends using the Sonus
SBC 5200

as an Access SBC between the SIP core and the LTE network (see fi gure 3). The Sonus SBC 5200 provides a
proven, scalable solution for secure IP-to-IP interconnect between core and access networks, including:
But.I.Thought.You.Needed.an.IMS.Core.to.Deploy.LTE?
In our example, Company A has elected not to deliver mobile voice services through the LTE network but will instead
continue to deliver the same fi xed-line VoBB services that are already offered through the WiMAX network. Where mobility is
not a requirement, VoLTE and VoBB are identical in functionality, and thus can utilize the same SIP core network (see fi gure
4). Company A has elected instead to enter into an MVNO relationship with a third-party GSM network operator, and no IMS
core is required because Company A is not concerned with managing the mobile handoff between the GSM and LTE networks.
NOTE: In cases where mobility is a requirement, VoLTE should be deployed with a 3GPP-
defi ned IMS core network in conjunction with a legacy GSM network. This confi guration
provides not only the service consistency between the IMS core and GSM access
networks, but also provides the requisite service continuity as mobile subscribers roam
between LTE and non-LTE coverage areas.
SIP
SIP
SIP
WiMAX
BTS
E-UTRAN
ASN Gateway
SIP
SIP
For Throtting and
DOS attack
WiMax to
LTE Migration
SG GW PDN GW
MME
HSS
DSI-1
ADS-1
ASX-1
ASX-2
PSX
PSX
Slave
PSX
Slave
SIP
SIP
D+
D+
D+
PSTN
SIP
SGX2K
EMS
Media Server
ICP
Hybrid
Trunking
DSI-2
ADS-2
Sonus
VoIP Core
IP Cloud
TDM Cloud
EPC
Figure 3 – WiMAX to LTE Migration with Service Consistency
via ASX and Security via Access SBC
>
Protection against DoS and Distributed DoS attacks
>
Media and signaling encryption
>
Load balancing and overload controls
>
SIP, H.323 and IPv4/IPv6 interworking
>
Media transcoding for HD and non-HD media codecs
SIP
E-UTRAN
SIP
For Throtting and
DOS attack
SG GW PDN GW
MME HSS
DSI-1
ADS-1
ASX-1
ASX-2
PSX
PSX
Slave
PSX
Slave
SIP
SIP
D+
D+
D+
PSTN
SIP
SGX2K
EMS
Media Server
ICP
Hybrid
Trunking
DSI-2
ADS-2
Sonus
VoIP Core
IP Cloud
TDM Cloud
EPC
Figure 4 – Sonus SIP Core with Access
SBC Deployed with LTE network
Adding.Mobility.to.the.LTE.Network.via.an.IMS.Core.Network
Since we’ve introduced the notion that Company A will partner with a third-party GSM operator to deliver mobile services,
let’s take it to the next logical step and imagine that Company A would like to bundle those services into a continuous
subscriber experience. This is a more common VoLTE scenario and will require an IMS core architecture to provide a Service
Consistency and Continuity (SCC) framework to manage sessions as they move between the core network, LTE network and
the third-party GSM network.
Fortunately for Company A, Sonus SIP core elements are designed to transition seamlessly into an IMS architecture (see
fi gure 5), fulfi lling key functions within the IMS core as follows:
>
The Sonus SBC 5200 which, as an Access SBC, provides SIP interoperability between the IMS and LTE networks and can
serve multiple, additional roles within the IMS architecture including:

Proxy Call Session Control Function (P-CSCF)

Access/Core Border Gateway Function (A/C-BGF)

Access Transfer Control Function (ATCF) and IMS Access Gateway (IMS-AGW) for voice call continuity

Emergency CSCF (E-CSCF) for E911 and other emergency services
>
The Sonus ASX Feature Server, which can be converted into a Telephony Application Server with a simple software
upgrade to support:

The IMS Service Control (ISC) interface to the Serving CSCF (S-CSCF)

Integration with the IMS core

The Sh interface to the Sonus ADS database or, if desired, for migration to a Home Subscriber Server (HSS) database
>
The Sonus SBC 9000, which can be upgraded via software to serve the roles of:

Media Gateway (MGW) and Media Gateway Controller (MGCF)

Interconnect Border Control Function (I-BCF) and Interconnect Border Gateway Function (I-BGF)
>
The Sonus PSX Centralized Routing and Policy Server, which can be upgraded to serve the Border Gateway Control
Function (BGCF) between the IMS core and the circuit-switched GSM network
>
The Sonus SGX Signaling Gateway, which would continue to act as an interconnect device to the SS7 network with no
upgrade required
In addition, Sonus works with partners to bring in the necessary IMS pieces for a best-of breed solution including:
IMS-SIP
Non-IMS
SIP
IMS-SIP
E-UTRAN
IMS SIP
IMS SIP
For Throtting and
DOS attack
ATC/AGW,
P-CSCF, C/A-BGF
LTE to 2G/3G
Network
SG GW PDN GW
MME
HSS
HSS
PCRF
BGCF
PSTN
SIP
MGCF/MGW and
I-BCF/I-BGF
SGX2K
Media Server
I-CSCF
S-CSCF
SCC AS
TAS AS
Sonus IMS Core
IP Cloud
TDM Cloud
EPC
GSM
BSC/BTS
MSC
ISUP or BICC
or SPI-I
HLR SMSC
3rd Party
Mobile CS
Core
Figure 5 – Sonus IMS Core with VoLTE via LTE network (fi xed) and Third-Party
GSM Network (mobile)
>
Radisys Convedia Media Server
>
Service Consistency and Continuity Application Server
(SCC AS)
>
Interrogating CSCF (I-CSCF)
>
Serving CSCF (S-CSCF)
Tying.It.All.Together:.Sonus.Global.Services
Over the years, Sonus Global Services has developed best practices for the effective migration of communications networks
that take into account network planning and architecture, subscriber data migration , SBC migration and other key technical
considerations. Sonus Network Migration Services are designed to help service providers seamlessly move legacy systems
onto new platforms and quickly reach ROI-driven milestones. Each migration engagement is led by a senior Sonus engineer
and backed by a world-class team of network engineers with specialized skills in network design, subscriber and trunk
migration, PSTN signaling interconnection and network security.
Sonus Network Migration Services include:
>
Subscriber data migration, integration and configuration
>
Risk management rollback procedures
>
Signaling, gateway ad call routing design modifications
>
Legacy equipment provisioning modifications
>
SS7/C7 signaling link installation and migration
>
Class 3/4/5 trunk installations and migration
Conclusion
Sonus Networks provides a cost-efficient and seamless migration path from WiMAX to LTE networks through its unique SIP
core architecture. By leveraging existing Sonus SIP core network elements, service providers can protect their investments in
hardware, architecture and internal skill sets. In addition, the Sonus solution allows service providers to have more flexibility
with their LTE deployment including:
>
The ability to run WiMAX and LTE networks in tandem using the service consistency features of the Sonus ASX server
>
A secure border between the LTE and SIP core networks via the Sonus SBC 5200
>
A simple, seamless migration from SIP core to IMS core that supports Service Consistency and Continuity.
The content in this document is for informational purposes only and is subject to change by Sonus Networks without notice. While reasonable efforts have been made in the preparation of this publication
to assure its accuracy, Sonus Networks assumes no liability resulting from technical or editorial errors or omissions, or for any damages resulting from the use of this information. Unless specifically
included in a written agreement with Sonus Networks, Sonus Networks has no obligation to develop or deliver any future release or upgrade or any feature, enhancement or function.
Copyright © 2012 Sonus Networks, Inc. All rights reserved. Sonus is a registered trademark, GSX9000, SBC 5200, SBC 9000, PSX, SGX2000 and ASX are trademarks of Sonus Networks, Inc.. All other
trademarks, service marks, registered trademarks or registered service marks may be the property of their respective owners.
Printed in the USA 05/12 WP-1163 Rev. B
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