Capacity: Delivering app coverage on the road to 5G

(Image Credit: iStockPhoto/powerofforever)

5G may be generating both hype and search engine optimization efforts but, for mobile operators, 5G is already a key consideration in their network strategy and planning. In other words, mobile operators are already on the road to 5G…

There are two recurring concepts that we see when we consider the network evolution to 5G:

  • The first is the concept of app coverage, which looks at network performance and capacity from the user perspective. This is how well the mobile apps you want to use work whenever and wherever you want to use them. Increasingly, app coverage won’t just be about mobile device users, but also about self-driving cars on connected highways, remote control surgery, and other machine-to-machine use cases as we evolve the Internet of Things.
  • The second recurring concept is not unique to 5G, but only becomes more pronounced as we envision this exponential growth in connected devices.  That is the issue of spectrum sustainability; making the best use of finite spectrum resources to support ever greater demands for app coverage from both people and machines.

Data gathered from mobile networks worldwide points to the fact that – as consumers – we are already living in a networked society and there is no sign of a slowdown as we look towards 5G. By 2020, it is forecast that 90% of the world's population over six years old will have a mobile phone. The majority of those will be smartphones, and 55% of mobile data traffic will come from video. In fact, because many of us have more than one subscription, mobile subscriptions are set to exceed the world population in 2015.

With the growth in consumer mobile broadband demand, and the rise in machine type communication (MTC), mobile networks worldwide will be carrying a projected 25 Exabytes of traffic per month by 2020, all of which needs to be transported over finite spectrum resources.

Making the best use of finite spectrum resources to support ever greater demands for app coverage from both people and machines.

As already stated, 2020 is when we expect to see the start of 5G commercialization. So when considering the supply vs demand issues, it is understandable that from a radio-access perspective 5G-related efforts will focus on; making more spectrum available (much of it in the higher frequency bands), small cell architectures (to accommodate the shorter range of higher frequencies), and harmonization between licensed and unlicensed technologies to optimize all available spectrum resources.

So what does the road to 5G look like and how do we know that we are getting there? If we look back at previous generational shifts in mobile technology, we see that the midpoint between 2G and 3G was referred to as 2.5G and progress in 3G led to 3.5G. With a new “G” emerging approximately every decade, 2015 should see us entering the 4.5G era. And there are certainly signs that this will be the case.

While LTE technology emerged as the enabler of 4G, it is also projected to be a key technology standard supporting 5G. So, advances in LTE technology may reflect key milestones on the road to 5G. According to GSA President, Alan Hadden, he states:  "LTE-Advanced carrier aggregation deployment was the major trend in 2014." (It is worth noting that, in this context, “carrier” refers to each 20 MHz portion of the spectrum band, not the operator running the network).

To date, carrier aggregation has been limited to licensed bands, but in 2015 we will see a new variant of carrier aggregation – License Assisted Access. This enables mobile device users to leverage the combination of licensed and unlicensed spectrum bands at the same time. LAA’s use of incremental higher-frequency 5 GHz spectrum on small cells – and its harmonization of licensed and unlicensed bands – echo the 5G radio access focus areas previously discussed which will perhaps mark the beginning of the 4.5G era.

LAA brings the reliability and performance characteristics associated with LTE to the unlicensed 5 GHz band (used by Wi-Fi, radar and other technologies) to increase peak throughput for mobile device users. Using just 20 MHz of unlicensed spectrum, about 4% of the 5 GHz band provides a speed burst up to 150 Mbps with each additional 20 MHz aggregated increasing the data rate by the same increment.

The technology employs fair sharing between licensed and unlicensed 5 GHz users. When an LAA-enabled device is in range of both licensed and unlicensed LTE coverage, the LTE network looks for the least busy portion of the 20 MHz of unlicensed band. Then, it listens for other access point traffic and will transmit (in brief millisecond pulses) in a manner that is fair with respect to the other access points within the band.

We see that the midpoint between 2G and 3G was referred to as 2.5G and progress in 3G led to 3.5G.

Fair sharing works on the principle that Wi-Fi and LAA users would have equal access to the spectrum. LAA uses the licensed spectrum to ensure LTE performance is maintained through reliable control signalling and robust, real-time user data with QoS, while leveraging the 5 GHz spectrum when available for an incremental speed boost.

If the unlicensed channels are unavailable for any reason, LAA maintains its licensed connection to support uninterrupted app coverage for the user. Of course mobile operators are already leveraging Wi-Fi to offload cellular traffic and support Wi-Fi Calling, but the user experience can degrade when Wi-Fi becomes congested and spectrum resources may not be optimized. LAA addresses both of these issues.

LAA deployments will be initially focused on indoor areas – not only because we spend more than 85% of our time indoors – but also because that’s where the capacity crunch seems to be hitting users the hardest. A recent Ericsson ConsumerLab study, conducted with more than 47,000 respondents across 23 countries, revealed that only 41% are highly satisfied with their indoor experience when browsing or accessing social networks. This drops to just 36% for more data-heavy apps such as watching video, TV or movies online.

LAA offers the promise of a rising-tide effect, benefiting all mobile device users. Those with LAA-enabled devices can leverage the combination of licensed and unlicensed bands to achieve higher peak rates; whilst users on cellular licensed bands only benefit because LAA distributes traffic between the licensed and unlicensed bands and frees-up capacity on the licensed spectrum. LAA also frees up capacity for Wi-Fi users, by employing fair sharing techniques and using the 5GHz band efficiently.

By effectively combining licensed and unlicensed technologies and leveraging higher frequency spectrum bands on small cell architectures, LAA is a key milestone on the road to 5G. LAA improves app coverage while optimizing available spectrum for all users. Welcome to 4.5G.

Should the industry focus on app coverage via "4.5G" before 5G? Let us know in the comments.

To learn more about the Internet of Things visit IoT Tech Expo Europe in London's Olympia, December 2-3, 2015. 

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