What is the connection between VoLTE and 5G networks? Spectrum and the ability for wireless carriers to refarm 2G and 3G spectrum for next-gen services
Operators around the world continue to make steady progress implementing voice-over-LTE services. According to the General Services Administration, as of April 2016, there were 494 commercially live LTE networks spanning 162 countries. Of these, a little more than 10% (55 operators) have launched a commercial VoLTE service in 34 countries. However, commercial momentum is building with an additional 25% (126 operators) currently investing in VoLTE deployments or trials. Feedback remains extremely positive with subscribers enjoying fast call connection and noise-free, high-fidelity call quality.
The marketing departments of these operators will go to great expense to convince their subscribers that this is what VoLTE is about – the provision of high-quality, high-definition voice calls. The truth, however, is that this masks a more pressing commercial imperative – the desperate need to free up spectrum with “5G” technology and the “internet of things” looming on the horizon.
In the vast majority of countries, operators have the luxury (and the burden) of owning multiple active networks – 2G, 3G and 4G infrastructure layered on top of each other that form an intermingled mesh of complementary technologies, each running in its own dedicated spectrum. Each generation is capable of more capacity, better quality and higher speeds. More importantly, each offers a dramatic step forward in spectral efficiency. To illustrate, the bandwidth consumed by a single 2G or 3G voice call can support more than 15 VoLTE calls. If legacy voice services can be retired, operators will free up 90% of the spectrum assigned to 2G and 3G voice.
The 5G reality: something has to give
Up until now, voice and data have seemingly been able to co-exist. LTE infrastructure has taken up the mobile data burden while 2G and 3G networks have by and large, though not exclusively, delivered the voice. Operators now realize the multiple heterogeneous network layers are at their limits in terms of meeting the daily demands of mobile subscribers. These users are accustomed to the faster speeds and improved user experience that 4G delivers. Their increasingly impulsive behavior and rising demand for pervasive mobile broadband access, regardless of service bandwidth requirements, creates expectations that only 5G networks can meet.
Furthermore, operators currently struggle to meet the spectrum requirements for effective 4G service delivery. Many carriers are looking to boost LTE coverage without having to invest heavily in small cells and hetnets. Currently, 3G networks have a lock on “sweet spot” lower frequency bands capable of longer transmission distances and deeper indoor penetration, where more than 60% of calls originate. If VoLTE – and higher-throughput LTE – is to replace what we have today, it needs to take advantage of these frequencies to ensure seamless, ubiquitous coverage.
The only answer to increasing speeds is to either free up inefficiently used spectrum or buy more. While most operators will continue to bid for new spectrum as and when it becomes available, many appreciate that the time is rapidly approaching to bite the bullet and switch off their 2G and 3G networks in pursuit of better 4G and ultimately 5G services. From a business perspective, many operators find purchasing new spectrum is becoming far more expensive and difficult than freeing up what they already own.
VoLTE to spell the end of 2G and 3G?
Operators can only realize the significant savings that will come from switching off 2G and 3G networks if they find a new and efficient way to deliver voice on next-generation 4G and 5G infrastructure.
While many operators accept this, others remain reluctant to take this step. In fact, some operators realize that without VoLTE ubiquitously deployed, they ironically need to invest in improving 3G voice quality to win over cost-conscious LTE subscribers. Consumers looking to upgrade to LTE services from 2G and 3G expect exceptional quality of experience for the premium tariffs they are being asked to pay. This is especially true in countries where LTE subscriptions are significantly more expensive than basic prepaid plans used by the majority of users, such as India, Brazil and the rest of Latin America. Upgrading to LTE in these countries will ultimately mean the user needs to invest in a smartphone for the first time.
These subscribers are unaware that while on LTE many voice calls are still carried over 3G networks. They expect their new plans to deliver an exceptional experience all around, for both voice and data. Although the main benefit of LTE is faster broadband, the principal way subscribers judge quality of experience is by voice quality.
4G networks without stabilizers: it can be done
Of course, the complexity tied to managing multiple network technologies and frequencies for the provision of high-quality voice only exists in countries where operators are combining multiple network layers. The trouble is that it accounts for the overwhelming majority of global operators. There are instances, however, of operators deploying greenfield LTE networks for the first time in areas where 2G and 3G infrastructure simply doesn’t exist.
This is the reality facing a major tier-one operator in India. In this case, VoLTE literally is the only way to deploy voice to its hundreds of millions of expected users. This operator is currently navigating a complex network environment to overcome interference while ensuring its subscribers are equipped with devices that support VoLTE – only the Apple iPhone 6 and 6 Plus models, plus a handful of new Android devices currently support VoLTE.
In order to overcome this level of complexity, a network must be sufficiently instrumented and tested prior to deployment. This level of instrumentation is vital in order to catch all VoLTE dropped call and quality issues, 80% of which occur in the backhaul and radio access network, and are therefore beyond the reaches of legacy test and monitoring equipment. Compared to the value of unlocking so much 2G and 3G spectrum, relatively light investment in this type of technological flexibility, which provides a stepping-stone to 5G, is really a drop in the ocean.
Scott Sumner is VP of strategic marketing at end-to-end network performance company Accedian.
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