Q and A: Virtualized VoLTE

Posted by Mae Kowalke on Tuesday, January 19, 2016 with No comments

What's behind the increasing investment in voice over LTE (VoLTE) on the part of network operators? Short-term, it's mostly about keeping up with data traffic growth and delivering voice services more efficiently. But there's much more to the story. Here, we dig deeper by answering some questions about VoLTE and its effect on operator business models.


How do operators stand to benefit by taking a virtualized approach to VoLTE?

Although legacy equipment can still operate and continue to carry traditional circuit-switched voice to handsets that are not yet VoLTE compatible, reconfiguration of the network will still be required. Call control management systems will need to be updated to include rules of which calls should be carried over 3G vs. VoLTE channels, and policy enforcement, mobility management, authentication and other systems will need to be similarly reconfigured.


Scalability and time to market are greatly accelerate by virtualization. This also applies to analytics, monitoring and network control. What would take well over a year to instrument a national network can be done in several weeks with virtualized performance assurance, as an example. When new regions light up service, the virtual infrastructure can be replicated and scale easily along with it. 

VoLTE will also benefit from distributed, remote packet capture to permit pervasive call quality analysis by deep packet inspection and call analyzers, so that these systems can be virtualized in of themselves, and also see more than their limited view at the core, today. With all-layer visibility, issues will be easy to isolate and optimize in ways that are not possible today due to the price of analyzers and the packet-brokers which are required to tap the network in a widespread way. 

How important is it that VoLTE services be 'quarantined' from existing service provision to enable easier containment of errors and malfunctions?

VoLTE will—and in early deployment has—face more significant issues than legacy services during provisioning. The main difficulties lie in the main benefit of the service: as an all IP voice call over LTE, it shares the same network as 4G data, which can easily overwhelm a link (and hence drop calls or squeeze out VoLTE traffic) during peak hours, traffic spikes, and under bursty input from IoT traffic.

What are some of the main challenges associated with VoLTE?


VoLTE traffic needs a dedicated ‘network slice’, with it’s own assured, priority class of service to ensure QoE goals are met, and reliability meets customer expectations for voice service. This class of service needs to be maintained and prioritized under all traffic conditions. As networks are increasingly burdened by video traffic, social media, browsing and other capacity hogs, voice bearers will need to be continuously monitored to ensure that these VoLTE ‘fast lanes’ are respected, and that network reconfiguration (e.g. by orchestrators of SDN controllers) don’t impact them.

Possibly the biggest problem with this transition will be ensuring calls don’t get dropped, or lost between the two technologies. In areas where VoLTE coverage is not present or sufficient for adequate QoE, call routing platforms will need to provide graceful fallback to 3G systems. These decisions will require continuous QoE monitoring, to make sure that the user receives the best experience possible—even if that means the call should not go over VoLTE when it is likely to offer an inferior service—to make sure that callers perceive this new service offering as an enhancement vs. a step backwards. New levels of network QoS and user experience visibility will be required to fulfill this need.

How quickly are operators likely to roll out wider VoLTE deployments? 


The availability of handsets, interoperability between carriers for roaming, the ubiquity and quality of LTE coverage, and the traffic engineering capabilities of the operator all pace roll-outs. In networks like Reliance’s Jio in India—a complete, nationwide greenfield LTE network targeting 100,000,000 users in 1 year—VoLTE will be deployed day one (and is the only option), so will be put to the test.

What's needed for VoLTE to become "telco grade"?


Operators are realizing that performance and exceptional user experience is a key differentiator so that they don’t have to compete solely on price—a trend that has cannibalized mobile profits and forced a zero-sum race to the bottom. VoLTE is an opportunity to differentiate and build loyalty, as well as reduce subscriber churn. To do this, they will need to establish complete end-to-end visibility of VoLTE QoE in real-time, and use this nervous system to control the network for optimal performance at all times, for every user. This method has been successfully deployed by SK Telecom, LGU+, and KT in South Korea, as well as by leading Japanese operators like Softbank. It will be replicated by many other leading mobile operators like Telefonica and AT&T. We will see the merging of performance monitoring, network control via SDN and big data analytics to meet QoE objectives in LTE and 5G networks.
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