Supporting operators as they introduce Voice over LTE

Transcription

1 1 / 3 Japanese Monthly Telecommunication Magazine, November issue 2012 Mr. Jukka Hongisto, Nokia Siemens Networks Solution Architect Supporting operators as they introduce Voice over LTE The first commercial Voice over LTE (VoLTE) services were launched in South Korea and the US in August We interviewed Mr. Jukka Hongisto, who heads up VoLTE at Nokia Siemens Networks, about the new technology s capabilities and potential Q. SK Telecom and LGU+ of South Korea and metropsc Wireless Inc. of the US started to offer VoLTE-based communications in August. What kind of services can VoLTE provide? Mr. Jukka Hongisto (J.H): VoLTE is a Voice over IP (VoIP) system based on the IP Multimedia Subsystem (IMS) used in LTE networks. LTE is a fully packet-switched technology with no provision for circuit switching. Therefore, a specific LTE voice solution is needed for smartphones. VoLTE provides that solution. One of the biggest advantages of VoLTE is that existing voice call functions are supported. For example, VoLTE supports emergency call origination and ring back, both of which are features not available with IP phones using OTT (Over The Top) services. Current trends in VoLTE and RCS implementation Q. With VoLTE, will mobile phone bills be lower than existing charges? J.H: Mobile operators do not distinguish between VoLTE services and existing voice call services and will want to maintain their current voice charging levels. Yankee Group Research Inc. predicts that the majority of revenue for mobile operators will come from voice call services. This makes it important to maintain the revenue from voice call services. VoLTE can help to make this happen by enabling richer voice services. In South Korea, for example, high-definition voice services using the AMR-WB codec have been a major focus. VoLTE can provide not only voice calls, but videophone services too. In addition, by using Rich Communication Suite (RCS), a technology common to VoLTE, operators can offer file sharing, multimedia communication and more. Already we are seeing these services beginning to be introduced. Furthermore, the time to connect a call over VoLTE is very quick, which will definitely attract users.

2 2 / 3 VoLTE also makes more efficient use of frequency than current call services and may help to reduce operational costs for the operator. In the medium to long term, this may lead to more competitive pricing. Q. Call services using Circuit Switched Fallback (CSFB) technology are being provided to LTE smartphones in Japan. How do these compare with VoLTE? J.H: LTE has already been commercialized by 89 telecommunication operators in 45 countries. However, the services provided are limited in most cases and operators are not yet able to offer VoLTE. As a transitional solution, voice communication is still run over the circuit-switched systems of 2G/3G. CSFB is one of these services. In CSFB, the smartphone or other device is connected to the LTE network when the device is in idle mode. But when a voice call arrives, a paging signal is sent to the device via the network s Mobile Management Entity (MME) and the call is handed over to the 2G/3G network from the LTE network. Many operators that have implemented W-CDMA/HSPA are expected to use CSFB. In addition to CSFB, there is also SVLTE (Simultaneous CDMA Voice and LTE data) that has been implemented since 2010 by CDMA2000 carriers like Verizon Wireless. Just like CSFB, SVLTE runs voice communications over 3G (CDMA2000). However, SVLTE is different from CSFB because a device within LTE coverage is always connected to both the LTE and CDMA2000 networks. Spread of LTE services in South Korea is 99% Q. Why has VoLTE been chosen and implemented in South Korea and US? Why not SVLTE? J.H: SK Telecom and LGU+ use the 800 MHz frequency band, which offers superior propagation characteristics, enabling the operators to build LTE networks that offer almost 99% service coverage. Therefore, even with VoLTE alone, the operators are able to offer practical services. As I mentioned earlier, a motive for choosing VoLTE is that the technology supports richer services. In 2013, a technology called Single Radio Voice Call Continuity (SRVCC) will be available for commercial use and will make it possible to implement VoLTE by complementing service

3 3 / 3 coverage with CS voice. SRVCC uses VoLTE for call communication over LTE, but when a smartphone moves outside the LTE coverage area, it can be handed over to 2G/3G bandwidth without interrupting the call. With this capability, operators can offer useful services even with limited LTE coverage. Q. Along with the three carriers in South Korea and US, which company do you think will be the next to implement VoLTE? J.H: Verizon Wireless, NTT Docomo and T-Mobile Germany are very actively investing in VoLTE. However, it is not known when they will actually commercialize VoLTE. Q. So, to sum up, you are saying that CSFB and SVLTE can provide the right capability for voice calls using smartphones, is that right? J.H: The choice of services to be deployed depends on the circumstances of the network. The NTT docomo 3G network, for example, covers most areas in Japan, making CSFB a very effective solution. On the other hand, when 2G GSM is the leading network and there is limited 3G coverage, CSFB is not feasible because data communication cannot practically be switched to GSM. Carriers in this situation may move positively to implement VoLTE. However, NTT docomo is a very advanced carrier. Therefore, they probably will implement VoLTE using SRVCC before LTE network coverage is widespread. In a tight Japanese market, they may eventually have to. Q. What does Nokia Siemens Networks offer on VoLTE? J.H: We are preparing a solution that will enable telecommunication carriers to roll out VoLTE step by step. As a concrete example, the implementation of CSFB would be the first step. Then, when the coverage of LTE networks is developed, VoLTE services can be introduced using SRVCC. Finally, when the coverage of LTE networks is about the same as the coverage of 2G/3G networks, CSFB and VoLTE are integrated so that CSFB is used for example for inbound roamers when needed. Nokia Siemens Networks has already started to help operators introduce commercial CSFB. We are also trialing SRVCC with Renesas Electronics Corporation. We offer everything needed to build an advanced network such as LTE radio, Packet core, IMS, application server, etc. With our resources, we can help operators make a smooth transition to VoLTE.

4 Noki CLIPPING NEWS Media: Telecommunication November issue Date: October 25, 2012 p Circ.: 38,000 Headline: Article: Focus Key Person Jukka Hongisto, Nokia Siemens Networks Solution Architect Supporting carriers move to VoLTE

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