Dan Warren, Director of Technology, GSMA, tells the story of how the industry developed the  will to form the common standard to carry voice over LTE

You may have heard of the VoLTE initiative, and may even be aware that it is a GSMA-led programme to define a common way to carry voice over LTE using an IMS. But how did the industry arrive at this level of co-operation, what is the difference between VoLTE, CSFB, VoLGA, GAN, CSoPS (and other abbreviations), and why is it now important to have a common approach to voice over LTE? Dan Warren, Director of Technology, GSMA, gives his view of how the future of voice over LTE was, and is being, defined.

In 2010, we will get a much clearer idea of the potential of Long-Term Evolution (LTE) networks to deliver fast mobile data services to large numbers of people. The world’s first commercial LTE networks were launched recently in Sweden and Norway by TeliaSonera, with Verizon Wireless in the US, NTT DoCoMo in Japan and China Telecom set to follow suit this year. But while we all get excited about what LTE will mean for apps, augmented reality, social networking, video-on-demand, Internet browsing and many other multimedia services, we shouldn’t forget that voice services still generate close to three-quarters of operators’ revenues worldwide.

Soaring demand for the menagerie of multimedia services may be driving the testing and deployment of LTE networks in Europe and elsewhere, but it is crucial that voice services aren’t an afterthought. Not only do LTE networks need to support high-quality voice calls, it is also vital that the operators running these LTE networks implement voice services in a consistent way, as they did with GSM.

A consistent approach to implementing voice services, together with the coordinated allocation of spectrum, has underpinned the extraordinary success of GSM both in Europe and worldwide. GSM and related technologies, such as HSPA, thrive because manufacturers can produce mobile phones that will work in many different countries, enabling them to achieve the scale necessary to create a very broad range of models at very low cost. Moreover, people with GSM phones remain contactable all over the planet because more than 700 mobile operators in more than 200 countries and territories have all implemented voice services in a consistent manner.

Going outside the standards
But this fundamental principle seemed to have been forgotten, at least temporarily, when it came to defining a voice implementation for LTE. When LTE was first conceived one of the early decisions taken by the standards body 3GPP was that LTE would be the first technology in the GSM family not to support circuit-switched connections. That decision is easy to understand: a single IP-based transport system is key to ensuring that LTE networks are efficient enough to carry large volumes of traffic cost-effectively.

Unfortunately, that decision also left a vacuum. Instead of an explicit statement of what should replace the circuit-switched domain for voice, there was just an implicit assumption that operators would provide voice services using an IP Multimedia Subsystem (IMS) and the related Multimedia Telephony Service (MMtel) standard – a framework within which specific applications for person-to-person communication, including voice services, could be defined.

But when MMtel was conceived in 2006, many operators were lukewarm in their support for IMS and there was some pressure to define an alternative means of implementing voice services on LTE networks. So, 3GPP began to define a circuit switched fall back (CSFB) approach as an ‘interim’ or ‘migratory’ solution, which operators could use until they were ready to adopt IMS. Unfortunately, this compromise also opened the door to other approaches and further fragmentation ensued. 3GPP also began to study a further interim or migratory approach, known as circuit-switched over packet-switched system (CS over PS).

But the emergence of these different solutions raised some uncomfortable questions. Wouldn’t these “migratory” solutions end up being used for a long time? (A mobile network needs to support a migratory solution as long as there are handsets in circulation that only support that solution.) In the meantime, the cherished GSM principle of interoperability might be jeopardised. Could a CSFB device roam on a CS over PS network, or vice versa? Could either roam on an IMS network? After considering such issues, 3GPP halted the CS over PS work. But soon afterwards the VoLGA Forum was established to continue the definition of CS over PS outside of 3GPP, and to support the provision of voice over LTE using the GAN (Generic Access Network) standard.

Getting back on the IMS track
Meanwhile, the industry still lacked a clear target for the IMS-based implementation that everyone now accepted would be the end goal. So, the One Voice group was formed to flesh out an IMS-based solution. The work of that group has now become the basis of the GSMA’s Voice over LTE initiative (VoLTE), which is aiming to accelerate the launch of IMS-based voice services, curtailing the period in which migratory solutions will be needed.

IMS has many merits: it can support all standard voice call service features such as call waiting, call hold and call barring, and is capable of serving large numbers of subscribers. IMS can also be used to integrate voice calls with enhanced, rich features such as presence, instant messaging and video content, across networks run by different mobile operators. Here at the GSMA, we are coordinating the development of the specifications that will enable interconnection and international roaming between LTE networks with the goal of completing that work by the first quarter of next year.

The GSMA is also working with mobile operators to ensure that LTE spectrum is aligned internationally, as far as possible, and that the VoLTE solution will also be fully-compatible with voice services offered by fixed-line operators.

The VoLTE initiative has the backing of more than 40 organisations from across the mobile ecosystem, including many of the world’s leading mobile operators, handset manufacturers and equipment vendors. The European mobile operators supporting the initiative include 3 Group, Deutsche Telekom/T-Mobile, mobilkom austria, Orange, Telecom Italia, Telefónica, Telenor, TeliaSonera and Vodafone.

These operators recognise the importance of maintaining the high level of global interconnection and roaming inherent in today’s 2G and 3G networks. Telefonica CTO Vicente San Miguel, for example, said in February that his company “strongly supports this initiative to drive a common voice and messaging solution for the mobile industry, as it is a key enabler for the success of LTE.”

With this level of support for VoLTE, the mobile industry should be able to ensure that the interoperability and global reach that characterises GSM-based voice services continues in an all-IP world. High-quality voice services that work everywhere are fundamental to the mobile industry’s raison d’être and we mustn’t forget that.

Advertorial – Huawei Femtocells: Coverage, Capacity and Business Growth

We are racing into a full Mobile Broadband (MBB) society. New mobile devices are announced in the world’s consumer media daily; together with a seemingly endless treasure trove of increasingly refined MBB applications these announcements are building a tidal wave of end use interest and expectations in the convenience and availability of mobile broadband. Whether for personal or business use, subscribers no longer look at MBB as nice-to-have, they see it a most-have prerequisite of daily life.

In Huawei’s view, the era ushered in by this tsunami of global interest, will experience continuous growth. This will be accelerated by the introduction of new, more affordable, devices, as well as increased data consumption per user, where convenience will exponentially drive rates of consumption and sharing. Huawei’s solutions are designed to allow operators to cost-efficiently respond to and profitably benefit from our projection of a minimum 500 times current level increase in mobile traffic by 2015. Within this span of just five years, we expect at least four billion mobile subscribers to be surfing this massive broadband wave of data intensive use – a stunning increase over existing MBB subscribers.

Mobile Broadband therefore represents considerable opportunity for operators. But, as ever, opportunity is never without its challenges: enhanced coverage and QoS when indoors, cost-effective networks with adequate capacity, ease of introducing new services and added revenue streams, these are just a few of the questions operators would like to see answered.

Huawei has responded to operator challenges the SingleRAN@Broad solution. Announced at MobileWorld Congress in February of this year, the first entire value chain solution for our fast emerging broadband world has the potential to make tremendous traffic both possible and profitable.
By affording enhanced coverage, expanded delivery capacity and added service delivery to residences and enterprises, Femtocells play a key role in this integrated solution. As a result, Femtocells offer operators the opportunity or growth and added competitiveness. In SingleRAN@Broad, this is represented by an end-to-end uBro solution encompassing a Home Femtocell as well as a Pico Femtocell serviced by its uBro Network and connected in turn to a mobile operator’s Core Network.

Why Femtocells?
Offering Coverage
It is well known that, principally due to the restraints of in-building penetration, high traffic bandwidth has been conventionally difficult to provide from Outdoor Macro. Considering MBB is mainly consumed indoors, operators need a cost-effective solution to cover those indoor areas which do not currently inhibit or even prohibit consistent user friendly MBB experiences.

Femtocells are the ideal tool for expediting a solution; providing 100% continuous coverage and full bit-rate. As an example of Huawei’s many commercial deployments, a profiled operator has managed to overcome building challenges while improving user experience thanks to a 25dB increase in signal level.

Delivering Capacity
For continuity of existing mobile networks and reuse of legacy networks, a traditional operator approach to sustaining MBB services is through standard Macro Deployment. In this manner, capacity is added by: improving technologies, e.g. HSPA+/LTE, adding new or refarming existing spectrum, 2.6GHz/900, or introducing new sites. The later creates almost insurmountable difficulties when attempted in dense urban areas.

Taking into account the indoor venues for the potential 500 times traffic increase in just five years, Huawei has introduced a multi cloud layer as part of the SingleRAN@Broad solution. In this scenario Femtocells are used to offload Macro networks, ensuring an enhanced MBB experience while making it expanded coverage affordable and ultimately, profitable.

The ease of Huawei Femtocells installation combined with a fully proven commercial  Plug & Play self-configuring solution; adapted portfolio; differentiated Home and Pico offerings supported through a shared infrastructure, together with a reduction of OPEX, energy and transport in particular, are now key drivers for Femtocells – affording operators considerable cost advantage when compared with traditional Macro Network solutions.

This cost advantage increases exponentially with the amount of data to be carried. According to Huawei’s calculations, Femtocells can offer at least a 50% reduction in the cost per Mb. Actual benefit will vary according to traffic, penetration and macro network status. Huawei has developed an in-house business case tool specifically to assist operators in understanding Femto benefits.

Enabling Growth
With localized coverage reinforced by Femtocell locking features as well as Femtocell integration into Home/Enterprise network, it is now possible to enable growth by introducing news services through Femtocells such as automatic content synchronization, mobile advertisement based on location, mobile monitoring,  PBX or VPN features,…

Why Huawei?
Complete Solution
Huawei’s end-to-end uBro solution has been custom designed to serve Home Zones as well as Pico Zones through its uBro Network.

Thanks to Huawei’s Femtocell portfolio, operators have the choice to select the best product for both
Home Zone and Enterprise Zone according to varying specific environment requirements. Selection is made according to:

Home AP                              Pico AP
UAP2105                              ePico3801
Service           Coverage                       ~30m                                     ~100m
Service           Users                               4                                            16
Features         Full Mobility                    Yes                                         Yes
Features         Plug & Play                    Yes                                          Yes
Operation        Performance               Simplified                            Powerful Monitoring
Operation        Configuration              Automatic                    Automatic and Manual(Offline)

Several other product mixes can be offered based on these basic components in order to simplify Femtocell installation and integration in different deployment environments.

Ready to Market
There are still many operators, analysis and other industry stakeholders who have doubts or questions regarding Femtocell technology and business case readiness. Technical issues, such as interference with existing Macro Network, management interfaces, or Femto standard readiness; and business concerns, such as value with regards to WiFi, and overall costs, are among the top concerns.

From a technical point of view, Huawei’s uBro solution is completely ready for commercial deployment today. We have developed several proven effective tools and strategies to effectively resolve any potential Macro Network interference. These include Femto Pilot Power Auto-Management, Mobility Management, and UE Transmission Power Management. As demonstrated by our participation in the Femto Forum PlugFest, Huawei’s uBro system is ready for 3GPP Iuh standards.  Last but not least, in order to make sure that management interfaces are open and easily integrated with existing Back Office Support Systems (BOSS), Huawei’s uBro management solution supports open protocols such as TR069 or SOAP.

From a business point of view, Huawei is ready today to help operators better understand target market segments and Femtocell cost savings as highlighted previously in this article. In our view and with particular relevance for smartphones, since Femtocells support all 3G devices and simplify their utilization, Femtocells will coexist with WiFi and will target different utilization patterns.

In Summary
At the start of this new decade, after several years of study and technical development, Femtocells are finally becoming main stream. As of the date of this article, the industry has seen no less than ten commercial Femtocell services deployed, three of which have been expedited by Huawei.  While mainly employed for coverage, Femtos also have the potential to become excellent tools for capacity absorption and enablers of new services and added revenue streams. With proven Fentocell solutions well in-hand, Huawei is completely ready to help operators expand mobile broadband coverage and enhance capacity growth.

Sharing the Load: The Value of Subscriber, Service, and Policy Control in Mobile Data Traffic Offload

Download White Paper