How to Deliver VoLTE with Scalability, High Performance in the EPC

By TMCnet Special Guest
Patrick McCabe
  |  September 03, 2013

(This article originally appeared in the Sept. 2013 issue of INTERNET TELEPHONY)

It is crucial that mobile network operators re-invent themselves and find ways to preserve and replace the significant revenue that they receive from legacy voice and SMS. With the right network delivery approach, VoLTE is a step in the right direction.

VoLTE and its importance to mobile network operators

The game really changes with LTE (News - Alert). With the emergence of LTE, and its increased bandwidth and QoS capabilities, mobile operators can now start to deliver specific data services with more consistent performance. One example is voice over LTE. VoLTE is an operator-owned voice service offered through the user’s LTE mobile data connection. It is delivered with specific performance characteristics, offering a more consistent and reliable experience to the user.

VoLTE is an important application to MNOs as it provides a way to protect their significant legacy voice and SMS revenues, which are threatened by OTT players such as Skype (News - Alert) and WhatApp, who are finding ways to monetize mobile data. At the same time, it opens up opportunities for new data services.

Delivering VoLTE will be more cost effective per customer than delivering voice through legacy circuit-switched networks and ultimately (with ubiquitous LTE coverage) could result in the elimination of a separate circuit-switched voice network. With an IMS VoLTE infrastructure in place, MNOs will have the opportunity to use VoLTE as a bridge to a variety of other communication services such as API-based application innovation, various types of videocommunication services, and WebRTC.

The challenges in delivering a new breed of LTE-driven mobile services

In general, the explosion in mobile data, the availability of smartphones and their applications, and the shift in user behaviors have created very unpredictable demands on the signaling (or control) plane of the MNO’s network. This is all about the network resources that need to process the instructions or rules on how the network should operate … dozens of chatty apps, constant idle to active and active to idle transitions, all are contributing to signaling plane traffic and result in very unpredictable demands on the signaling resources.

With the emergence of LTE, service expectations will be very high as users will no longer tolerate best-effort performance and will expect services and performance tailored specifically to their individual needs. For example, if we look specifically at VoLTE, the underlying IP packets are very small and as such demand a high packet transmission rate. VoLTE packets must be delivered with little delay but can tolerate some packet loss. However, when delivering VoLTE with, let’s say, video then the requirements are almost flipped. The operator must deliver these services with widely different requirements concurrently.

In addition, many Internet services require a deeper level of packet inspection to identify specific underlying services, (e.g. social media, gaming, etc.) so that mobile operators can treat (QoS, charging, etc.) these packet flows uniquely.  This is often performed with what is known as deep packet inspection technology and represents another dimension of processing that is expected today.

Mobile networks will have to deal with a lot more stringent and rigorous processing requirements than in the past. Legacy networks (in particular legacy 2G/3G) mobile gateways are not built to handle these demands. Common CPU-based architectures require the operator to trade off control plane scalability with data plane scalability. Increase one and the other falls.

The right approach to deliver VoLTE

To be successful in the new era of LTE and beyond it’s all about being able to independently scale the mobile network in multiple dimensions independently. Mobile operators need to prepare for the upcoming onslaught of traffic demands in their packet core and in particular on their mobile gateways.

The packet gateway is the IP anchor point of the mobile network and represents the primary enforcement point where a lot of the heavy lifting is done with respect to service processing for each packet flow. It is essential that the packet gateway is able to support massive scale across the multi-dimensional service processing demands mentioned earlier: control plane for network instructions, the data plane for multi-services like VoLTE, and the advanced data plane for deeper levels of packet processing required for many Internet services.


Patrick McCabe is in senior marketing management at Alcatel-Lucent (News - Alert) (www.alcatel-lucent.com).

Edited by Stefania Viscusi