15-leading edge--evolution and deployment of volte

8/2/2019 15-Leading Edge--Evolution and Deployment of VoLTE

http://slidepdf.com/reader/full/15-leading-edge-evolution-and-deployment-of-volte 1/4SEP 2011

.

ISSUE 61

Huawei Communicate

Evolution and deployment of

Four approaches tomobile broadband voice

n the near uture and ater theevolution rom DM to IP androm traditional switches tosotswitches, mobile voice services

will evolve to mobile broadband (MBB)voice services. In terms o network evolution, it will mean the evolution o

GSM/CDMA/UMS to LE on theradio network side and the evolutiono CS to IMS on the core network side. Over the last ew years, there havebeen multiple views, technologies, andevolution paths or LE voice services.

At last, our approaches have beenaccepted as possible commercial choices.

Te rst approach is based on circuit-switched allback (CSFB). LE justprovides data services, and when a voicecall is to be initiated or received, it will all

I

back to the CS domain. When using thissolution, operators just need to upgradethe MSC instead o deploying the IMS,and thereore, can provide services quickly.However, the disadvantage is longer callsetup delay. However, in most cases, theCSFB solution is suitable as an interimsolution prior to the deployment o IMSsupported services. In addition, it canalso be used to handle voice calls in thescenario o LE roaming. For example,

when the network in the visited network does not have the IMS or when the IMSroaming protocol is yet to be deployed,CSFB can provide voice-call service orinbound LE roamers.

he second approach is based onsimultaneous voice and LE (SVLE),

which is the dual radio handset approach.In this approach, the handset workssimultaneously in the LE and CSmodes, with the LE mode providingdata services and the CS mode providing

the voice service. Tis is a solution solely based on the handset, which does not havespecial requirements on the network anddoes not require the deployment o IMSeither. he disadvantage o this solutionis that the phone can become expensive

with high power consumption. Currently dual radio handsets eaturing CDMA 1xand LE are already available and usedby some CDMA operators as an interimsolution prior to the deployment o IMS,

while dual radio handsets eaturing GSM/UMS and LE are not yet available.

he third approach is based on theusage o over-the-top (O) services,using applications like Skype and Googlealk to provide LE voice service. LEboasts eatures like broad bandwidth,low latency, being always-online, and

All-IP, creating natural convenience orthe development o O and makingO voice calls almost barrier-ree.However, we should also note that now

By Chen Qunhui

52


http://slidepdf.com/reader/full/15-leading-edge-evolution-and-deployment-of-volte 2/4

Leading Edge

SEP 2011.

ISSUE 61

and in the oreseeable uture, the voice call serviceis, and will still be, the main revenue source orthe mobile operators. So handing the LE voiceservice over completely to the O actors is thussomething which is expected to not receive too

much support in the telecom industry.Compared to O, telecom operators have

their own unique advantages in providing LEvoice calls, such as user ID resource, standard-based interconnection, QoS assurance, the ability o handover to CS, and tari package bundled

with data service. In the uture, the percentage o O calls may increase drastically, especially orthe long-distance call. However, the call serviceprovided by telecom operators will still be themainstream or a long time.

Te ourth approach is the IMS-based VoLE. IMS

has become the core network’s standard architecturein the All-IP era because it supports multiple accessmodes and a wide range o multimedia services.

Ater developing and maturing over the last severalyears, IMS today has crossed the chasm to becomethe mainstream choice or VoBB and PSN network migration in the ixed-call ield, and has also beenidentiied as the standard architecture or mobilevoice service by 3GPP and GSMA.

O the above approaches, both CSFB andSVLE rely on the CS domain to provide voiceservice and both have some limitations. hey can

be used as the interim choice and non-mainstreamapplication, which we call pre-VoLE. Only IMScan provide a voice solution with the QoS assurancebased on LE. In other words, the IMS-basedVoLE is the inevitable path or the development o the wireless and core network technologies.

For the operators, deploying VoLE meansopening up the road or the evolution towardMBB voice service. In the long run, this will createvalue or the operators in two aspects: One o

which is increasing the utilization rate o wirelessrequencies and reducing network costs, because

or voice service, LE’s requency utilization rateis ar higher than that o the traditional systems –more than our times higher than that o GSM.

Another important advantage is that it willimprove user experience, as IMS-based VoLEservice will be signicantly better compared witha traditional CS based service. For example, theintroduction o HD voice and video codec willsigniicantly improve call quality. he call setuptime o VoLE will be dramatically shortenedcompared with the pre-VoLE options. estshave proven that the call setup time or a VoLE-

based call has decreased to more than hal whencomparing with call based on CS. Finally, theseamless integration with the Rich CommunicationSuite (RCS) oers the opportunity to generatemany new and attractive services.

Development stages

Stage one: Pre-VoLTE applicationsemerge with LTE hotspot coverage

Initially, LE ocuses on hotspot coverage,mainly providing MBB data applications orusers with data cards and tablet PCs. However,there will also be some early-stage LE voiceapplications. Te rst is the voice service based on

the sot clients, in the orm o “LE data card +sot client + PC”, which can meet voice needs insome speciic scenarios and help operators makepreparations and accumulate operating experiencesor the deployment o the handset-based VoLEin the uture. Te second is the orm o “LE CPE+ ixed phone”. Some European countries, suchas Germany, use this orm to provide broadbandaccess and voice call service or users in the remoteregions. he third is the early-stage LE phonessupporting CSFB and SVLE. Some operators havelaunched interim applications: For example, Verizon

has announced that it will support SVLE, while A& has announced that it will support CSFB.

Stage two: VoLTE applications on therise with LTE continuous coverage

At this stage the operators will have increased thecoverage o LE, and be able to provide voice services,especially in cities and densely populated areas.Meanwhile, the advent o LE smartphones in largenumbers will have driven the development o VoLE.

he ope ra to r s w i l l l aunch IMS-ba sed

commercial VoLE services at this stage. However,prior to this, the operators need to have a longpreparation period or the ollowing reasons.On the one hand, VoLE involves many newtechnologies and requires necessary tests and trials;on the other hand, the deployment and integrationo IMS takes time, and some systems in theexisting networks such as MSC, HLR, and Isystems may need a corresponding consolidationor upgrade. We think that it is necessary or theoperators to begin preparing or VoLE one yearin advance or even beore.

Evolution and deployment of VoLTE

53



Leading Edge

SEP 2011.

ISSUE 6155

Adjustment o or interconnection to the existingnetwork’s equipment is oten the hardest part. othis end, we should think about how to reduce oreven eliminate the adjustment o existing network equipment such as MSC/HLR on the one hand.

On the other hand, we should also think aboutthe coexistence and integration with the existingnetwork equipment.

o support SRVCC or handover to CS andCSFB or inbound roaming, the operators shouldupgrade the MSC. However, large-scale network upgrade is difcult, involving a long cycle and highcosts, and thereore should be avoided during theinitial period o VoLE development i possible.Functions such as SRVCC/CSFB can be centrally deployed to one or a small number o MSCs. I it’sdiicult to upgrade the existing network’s legacy

MSC, we suggest that a new MSC be introducedto serve as the MGCF, SRVCC IWF, or CSFBProxy, to replace upgrading legacy ones.

In addition, although ICS is taken as the targetarchitecture in the uture, deploying ICS wouldrequire the upgrade o MSC-S throughout thenetwork in the initial stage o VoLE. his istoo costly or many operators. Huawei’s VoLEsolution provides two options: deploying ICS ornot deploying ICS. In the model o not deployingICS, ater LE users have roamed to the CSdomain, the service is completely processed in

the CS domain, and there is no need to trigger itto IMS. his can not only avoid MSC upgradeand shorten time-to-market, but also increase theequipment’s processing efciency.

For the deployment o HLR/HSS, we suggestthat an overlapping solution is used initially, which isto overlap a converged HLR/HSS to manage LE’suser data, and to keep legacy HLR or traditional CSunchanged. Tis can avoid the huge work o upgradingHLR throughout the network at the very beginning.

In addition, the deployment o VoLE involvesmany network elements such as IMS Core,

AS, SBC, and converged HLR/HSS, and somenetwork elements may be already in existenceor certain services such as VoBB. As such, thenew equipment introduced to VoLE should beeasy to be integrated with the existing network’sequipment. For example, CSCF and AS may be rom dierent vendors, and the IO andintegration between them should be addressed.

Enriching service experience

VoLE will provide better voice and video call Editor: Li Xuefeng [email protected]

quality and aster call setup speed, but these reasonsare not suicient or replacing the traditional CS.More abundant applications beyond voice arerequired in MBB stage. On the other hand, acingthe competition rom O, telecom operators need

to provide similar or more competitive services. RCSor the simpliied one, RCS-e, introduced by someEuropean operators can provide rich communicationexperiences, including IM, image and video sharingon the basis o voice service as well as the integration

with the Internet services. hereore, the RCS isexpected to be widely adopted and deployed. In asense, the development o VoLE cannot do withoutRCS. Operators should consider the integration withRCS when deploying VoLE, and because both o them are based on IMS, the seamless integration o VoLE and RCS is also possible.

Acceleratedcommercialization

Ater several releases including 3GPP R8/R9/R10, as well as the improvement by GSMA, VoLEstandards and technologies are already mature. In2011, the industry has two signicant developments:One is that more and more tests and trials are takingplace, the other is the advent o the LE smartphones.

In the core network ield, all the major IMS

vendors have plans to support VoLE, and are actively conducting tests and trials with the operators. Whatis especially worth noting is that in May 2011 IMC(International Multimedia elecommunicationsConsortium) organized the industry’s irst VoLEIO test in Hawaii, during which, Huaweiexclusively provided an entire suite o the LE/EPC/IMS network equipment and completed the test o interconnection with the terminals. In September2011, MSF (Multi Service Forum) will also organizean IO test involving multiple vendors.

In 2011, some terminal manuacturers such

as Samsung and HC announced the irst LEsmartphones. Tis was an important milestone orthe LE industry. However, these terminals mainly support CSFB and SVLE. Based on the progresso mainstream chip makers and handset makers,it is expected that smartphones that support theIMS-based VoLE and SRVCC will becomecommercially available in 2012. Some operators inNorth America, Russia, Middle East, and Europeare expected to become the irst providers o VoLE services rom 2012 to 2013.

Evolution and deployment of VoLTE

15-leading edge--evolution and deployment of volte

Documents