Showing posts with label LTE Voice and SMS Issues. Show all posts
Showing posts with label LTE Voice and SMS Issues. Show all posts

Thursday, 10 December 2009

VoLGA = 1, other VoLTE = 0

From Unstrung:

Deutsche Telekom Announced First Voice Calls over LTE with VoLGA. Deutsche Telekom announced today the world’s first voice call over LTE with excellent speech quality based on VoLGA (Voice over LTE via Generic Access) technology and two independent test environments.

Calls have been made between a test system, installed at Deutsche Telekom Headquarters in Bonn, Germany which is based on a VoLGA implementation of Kineto Wireless and a second totally independent system from Alcatel-Lucent, installed in their test center in Stuttgart, Germany. Both VoLGA-based Voice over LTE systems support inbound and outbound voice calling and SMS messaging between LTE-enabled devices and standard mobile and fixed telephones.

With this result Deutsche Telekom underlines the innovative leadership in the development of Next Generation Mobile Networks (NGMN), as it belongs to a series of tests through which the company consequently researches the capabilities of the potential NGMN technologies.

“Voice calling is an essential service for mobile operators. This demonstration is a key milestone towards establishing a future proof eco system and shows a cost efficient way for using voice over LTE”, stated Uwe Janssen, Senior Vice President of Core Networks. “The VoLGA test shows how operators could quickly and easily provide next generation voice services, re-using their existing core networks. At the same time this serves as a first step to prepare networks for the industry-agreed mid- and long-term solution for voice over LTE that will be based on IMS.”

In other related news from Fierce Wireless:

Ericsson has dropped its support for the VoLGA Forum, which promotes Voice over LTE via Generic Access, dealing a blow to the voice-over-LTE approach a little more than a month after the vendor signalled its enthusiasm for a different standard.

Erik Ekudden, Ericsson's vice president of technology and industry, said that when the VoLGA Forum was established earlier this year "we had the impression that VoLGA would become a global solution." However, "there are no signs that it [VoLGA] will be strongly supported" by mobile operators, he said in an interview with Unstrung.

Picture Source: Into Mobile

Friday, 6 November 2009

'One Voice Initiative': IMS Based approach adopted

AT&T*, Orange, Telefonica, TeliaSonera, Verizon, Vodafone, Alcatel-Lucent, Ericsson, Nokia Siemens Networks, Nokia, Samsung Electronics Co. Ltd., and Sony Ericsson have defined the preferred way to ensure the smooth introduction and delivery of voice and SMS services on Long Term Evolution (LTE) networks worldwide.

The above telecommunications industry leaders have jointly developed a technical profile for LTE voice and SMS services, also known as the One Voice initiative. The profile defines an optimal set of existing 3GPP-specified functionalities that all industry stakeholders, including network vendors, service providers and handset manufacturers, can use to offer compatible LTE voice solutions.

Open collaborative discussions have concluded that the IP Multimedia Subsystem (IMS) based solution, as defined by 3GPP, is the most applicable approach to meeting the consumers’ expectations for service quality, reliability and availability when moving from existing circuit switched telephony services to IP-based LTE services. This approach will also open the path to service convergence, as IMS is able to simultaneously serve broadband wireline and LTE wireless networks.

By following the jointly defined technical profile, the industry can help guarantee international roaming and interoperability for LTE voice and SMS services, ensuring subscribers continuity of these vital services – all while offering service providers a smooth and well-defined path to LTE.

The objective of the initiative is to ensure the widest possible ecosystem for LTE and to avoid fragmentation of technical solutions. LTE will, with this initiative, not only serve as a broadband access for increasing data traffic, but also for continuing voice and SMS services. Network operators will be able to more quickly develop their customized LTE ecosystem in collaboration with both network equipment vendors and device manufacturers. In addition, the reassurance of global interoperability in an LTE voice landscape and the ability to offer both broadband access and telephony services over LTE will create strong foundations for future business.

The profile for the initial solution has been finalized and is available through the companies associated with this press release. The objective is to hand over the profile and continuing work to existing industry forums.

To view the technical profile, please visit

From Rethink Wireless:

One of the trickiest issues for early LTE deployers is uncertainty over how voice and SMS services - still the key cash cows for most operators - can be supported. Eventually, all these services will be carried over IP, using the IMS (IP Multimedia Subsystem) standard, but only a few carriers, like Verizon Wireless, are looking to deploy all-IP from day one. However, there is pressure to accelerate the process and reduce the cost and risk of LTE/IMS for carriers, and this is the objective of the new One Voice initiative.

Some operators believe they will initially deploy LTE as a data-only network, but most want to support voice and, even more importantly, SMS (which underpins many cellco processes and customer communications). Faced with the risk that large players might delay their plans until they have a strong route to voice, One Voice has defined a profile based on existing 3GPP standards for IMS-enabled voice.

The work has initially emerged from Nokia Siemens, which was previously trying to get wide industry support for its own interim voice over LTE solution, VoLTE (which only worked with its own softswitches). The company's convergent core marketing manager, Sandro Tavares, said One Voice should ease fears over how voice will be deployed by resolving roaming and interworking issues at an early stage. It is not creating a new standard, but aims to ensure compatibility between networks and devices by creating a common profile, which defines an optimal set of existing 3GPP functionalities for use by vendors and operators. "There is no new standard," added Tavares. "It's just using what is there already."

NSN is already producing LTE equipment that complies with the new profile, and so has a headstart in offering an important feature to early triallists - which could boost its so-far low profile in LTE tests, dominated by Ericsson and Huawei. However, the vendor will now hand its work to the 3GPP and GSM Association so that other companies can work on and adopt the profile. So far, it has signed support from most of the key operators that tend to wield influence over cellular standards, apart from DoCoMo and China Mobile - AT&T, Orange, Telefonica, TeliaSonera, Verizon Wireless and Vodafone are there, plus a strong line-up of vendors. These are Alcatel-Lucent and Ericsson on the infrastructure side and Nokia, Samsung and Sony Ericsson for devices. The group needs to get the Chinese vendors on board to complete the set, as well as Motorola.

The supporters of the initiative say this is their "preferred path" for voice over LTE, though for carriers that do not want to move to IMS at an early stage, there are other options available - namely open web-based voice; the stopgap solution of Circuit Switch Fallback (also enshrined in 3GPP standards), where the handset is forced off the LTE network onto 2G or 3G for voice calls; and variations on the theme of using circuit switch over packet techniques. There are two main approaches to this - MSC Voice, which is tied to a switch, with NSN's VoLTE the most prominent example; and VoLGA, which is architecture independent, and uses the UMA/GAN (Unlicensed Mobile Access/Generic Access Network) protocol. This Kineto originated technology was originally adopted for Wi-Fi/3G fixed-mobile convergence and as such did find its way into the 3GPP. VoLGA does not require modifications in the LTE RAN or core, or the MSC, but uses a separate gateway controller.

Some of the One Voice supporters are already involved in VoLGA (though its major carrier T-Mobile has not yet joined the new group). Steve Shaw, who heads up corporate marketing for Kineto and VoLGA, believes that IMS is the way that, ultimately, voice will be handled, but it has a long way to go before it is usable, and so there will still be a role for several years for approaches like VoLGA.

T-Mobile will I assume soon have to follow suit and fall in line otherwise they may have limited devices that are available and there will also be inter-operability issues.

Last week I attended a presentation by IET Berkshire on Voice Services over LTE, presented by Iain Sharp from Nortel. Even though this announcement came yesterday, Iain did say that IMS is the way forward for Voice over LTE. If interested you can see the presentation here.

Friday, 28 August 2009

Whitepaper: Voice over LTE via Generic Access (VoLGA)

Martin Sauter has published a whitepaper on VoLGA. I havent read it as of yet but I am sure it will be an interesting read for people who are interested in learning more about Voice options in LTE.

The whitepaper can be found here.

Feel free to post comments regarding the whitepaper on Martin's blog here.

Sunday, 12 July 2009

Stage 2 Specification For Voice Over LTE from VOLGA Forum now available

From our friend Martin Sauter's blog:

Regular readers of this blog probably remember that I'm a fan of Voice over LTE via GAN (VOLGA). For those who don't, have a look here on more details on why I think it has a good chance of becoming THE voice solution for LTE. It's amazing how fast the Volga-Forum is pushing out the specifications. In May, they published the stage 1 specification document, which contains a high level architecture and the requirements. Now only a month later, a first version of the stage 2 specification is available. Stage 2 specifications as per 3GPP contain a detailed architecture description and all procedures required from connecting to the network, originating and terminating calls, doing handovers, etc.

While their speed is incredible, maybe it should not be that surprising, because VOLGA is based on the already existing 3GPP GAN (Generic Access Network, i.e. GSM over Wi-Fi) specification. That's a good thing because that means that VOLGA could thus be developed quite quickly as it's likely that existing products can be modified instead of being designed from scratch. In addition, this should also mean that the first version of the standard is already quite mature as many areas were already verified during implementation and rollout of GAN in current networks.

I did a quick comparison between the two stage 2 specs and as I expected, many parts are very similar. While the GAN stage 2 specification has 126 pages, the current VOLGA stage 2 specification has 87 pages. This is probably because VOLGA is simpler than GAN. There are fewer handover procedures and most of the handover details are part of the 3GPP Single Radio Voice Call Continuity (SR-VCC) specification (for IMS) so they don't have to be included in the VOLGA spec. In addition to fewer handover scenarios, handovers are a bit more simple with LTE from a VOLGA perspective, as the network takes care of it unlike with GAN, where the mobile has to force the network into a handover. Also, there's no need to support the packet switched part of the network which also significantly lowers the complexity.

Well done, I am looking forward to the stage 3 specification which will contain the details on all messages and information elements used.

I blogged about VoLGA last month here.

Wednesday, 10 June 2009

VoLGA: Bringing Voice to LTE

Voice is becoming an Important issue for seamless introduction of LTE services. Even though most people think that LTE will start with the Broadband Dongles, it is important to resolve the issue sooner rather than later.

VoLGA Forum is one such body proposing a solution and its backed by quite a few well known industry players.

In the LTE World Summit, Franz Seiser of T-Mobile Germany spoke about VoLGA. Here is a summary from his presentation:

In order to ensure LTE will be used as much as possible, voice-and messaging services need to be supported on LTE networks in high quality asearly as possible.

The main Drivers being:
  • Ensure acceptance of LTE as an possible next generation PLMN
  • Shift traffic to new network as fast as possible
  • Avoid price competition with DSL
The industry needs a stable, scalable voice and SMS solution forLTE:
  • delivering a seamless user experience (voice hand-over to existing 2G/3G networks)
  • with proven, commercial quality
  • availability in 2010 (SMS) /2011 (voice) latest

In a post earlier, I discussed about the possible voice options for LTE and that generated quite a discussion relating to GAN. Recently Dean Bubley and Martin Sauter have covered this VoLGA issue and in general Voice over LTE in far more detail than I have earlier or even in this post. Please see the links at the bottom to read their post details.

Specified 3GPP solutions for Voice/SMS in LTE do not meet all requirements because:

CS Fallback ruled out due to customer experience and non-LTE usage

  • issues with customer experience (call set-up time increase >1.5sec., no parallel voice/data if legacy network is 2G w/o DTM)
  • not using LTE radio for voice
  • requires changes to Rel-4 architecture MSC-Servers
  • has much more impacts than originally envisaged

IMS based solution has very high complexity; availability and stability notfeasible in time, roaming eco-system is not yet existent

  • solution would consist of IMS platform, various application servers and a major upgrade/change to Rel-4 architecture MSC-Servers
  • no eco-system in place yet for IMS voice/SMS roaming and interconnect (only GPRS data or CS eco-systems are available today)
  • solution requires updates/changes to quite many IT systems and processes as well

Key Objectives for Voice/SMS over LTE Solution is to Re-use as much as possible of existing systems, mechanism and eco-system while avoiding proprietary extensions to 3GPP nodes

  • build upon existing Rel-4 CS network and investments
  • “do not touch the MSC”
  • build upon fully 3GPP compliant Rel-8 EPC/LTE network
  • re-use existing CS roaming/inter-connect regime
  • minimise impact on UE, especially on user-interface

As a result, the simplest solution is “Voice over LTE Generic Access” or VoLGA

What is VoLGA?
  • A technological approach for delivering voice and SMS services over LTE access networks
  • Leverages a mobile operator’s existing core voice network
  • Derived from the existing 3GPP GAN standard

What is the VoLGA Forum?

A group of companies working to…

  • Leverage collective technical skills to define VoLGA specifications
  • Publish proposed specifications via the VoLGA Forum web site (coming soon)
  • Facilitate the easy adoption of VoLGA technology by other vendors and operators

The group is open to interested parties in the mobile community

The main Highlights of VoLGA are:

  • Full service transparency
  • Supports all circuit services over LTE
  • Supports IMS RCS and combinational services (CS+IMS) over LTE
  • Supports handover of active calls between LTE and GSM/UMTS
  • Supports expected LTE femtocell deployments
    • Low risk, low investment
    • Based on well proven 3GPP GAN standard
    • Requires no change to existing MSCs and operational systems
    • Conserves existing, extensive voice interconnection regime

    To keep things simple, VoLGA is the best option available at the moment.

    Further Reading:

    You can search multiple blogs (including mine) in a single search via the 3G4G search here. (Search at the bottom of the page).

    Sunday, 23 November 2008

    Solving the LTE voice dilemma

    Continuing the discussion from LTE World Summit, this is something that has been discussed in the past by myself and other blogs as well. We know that there is no out of the box solution for voice calls in Release 8 but there are some solutions that are being standardised for this problem. Dr. Howard Benn, Director of Cellular Standards, Motorola Mobile Devices gave an interesting presentation on this topic titled, "Voice –how to talk over LTE". Here is the summary of his presentation along with some more information:
    As we know, IMS was introduced in Rel 5 but even till today, there has been no major IMS rollouts. There are some operators working on deploying the IMS solution but in reality its not been as successful as it should have been. If IMS is available then the problem of voice call on LTE goes away. The problem can be solved using Voice Call Continuity or VCC. Infact there is a bunch of specifications on IMS Centralized Services (ICS) and network Centric VCC for solving this and other similar problems.

    So with IMS not being available, the first alternative for this problem is Circuit Switched Fallack (CSFB). In this, as can be seen from the MSC above, the user is attached to an LTE network. MSC can send Paging to the UE and if the user accepts the voice call then he is handed over to 2G/3G network. The big problem with this approach is additional time required to establish the voice call and the PS services might get disrupted, depending on how its handled.

    The second solution is to have a Generic Access Network (GAN... previously known as UMA) based solution. This is similar solution to the ones used by some Femtocells. This would mean that the UE's would require GAN chipsets and GAN is known to be power hungry so it can impact the battery life significantly.

    China Mobile's, Bill Huang in a recent interview mentioned that “We could carry voice over UMA” and “We will have an LTE network that supports voice…”. He was referring to this approach mentioned above.

    Finally there are always proprietary options like Skype that can be used along with the data services to solve the voice problem.

    Infact a service like Vonage, modified for mobiles, can solve this problem easily. You can connect a VoIP client from your phone or device to Vonage and you are given a landline number that you can pass to others. When calls are received on this number, the client in the mobile rings and you answer the call normally.

    Nick Yamasaki from KDDI mentioned that KDDI will roll out LTE with CS fallback option for voice initially but then SRVCC (Single Radio VCC) solution will be adopted in future.