(Image Credit: iStockPhoto/powerofforever)
5G generates a lot of attention and marketing, but for mobile operators it is already a central part of network strategy and planning. In short, operators are already on the road to 5G.
Two recurring themes appear when considering network evolution toward 5G:
- App coverage: This evaluates network performance and capacity from the user’s perspective—how well the mobile apps you rely on work wherever and whenever you need them. App coverage will increasingly include not only phones and tablets but also connected vehicles, remote medical procedures, and countless machine-to-machine applications as the Internet of Things expands.
- Spectrum sustainability: Although not unique to 5G, this concept grows in importance as the number of connected devices rises exponentially. It focuses on making the best use of finite radio spectrum to meet ever-greater demands for app coverage from people and machines.
Global network data shows we already live in a deeply networked society, and demand continues to rise as we approach the 5G era. By 2020, forecasts suggested that 90% of the world population over six years old would own a mobile phone, most of them smartphones, with video accounting for about 55% of mobile data traffic. Many people have multiple subscriptions, and mobile subscriptions were expected to exceed the global population in 2015.
With consumer mobile broadband growth and expanding machine-type communications, global mobile networks were forecast to carry roughly 25 exabytes of traffic per month by 2020. All that traffic must traverse finite spectrum resources, which makes efficient spectrum use a critical priority.
Making the best use of finite spectrum resources to support ever greater demands for app coverage from both people and machines.
As commercialization of 5G approaches, radio-access efforts are expected to concentrate on three main areas: freeing up more spectrum (including higher-frequency bands), deploying small-cell architectures to suit shorter-range high-frequency signals, and harmonizing licensed and unlicensed technologies to maximize all available spectrum.
How does the road to 5G look, and how can we measure progress? Historically, midpoints between generations have used fractional labels—2.5G between 2G and 3G and 3.5G as 3G evolved. With new generations emerging roughly every decade, 2015 marked the start of what some termed the 4.5G era, evidenced by advances that also feed into the 5G roadmap.
LTE helped enable 4G and is projected to remain a core technology for 5G. Improvements in LTE therefore serve as milestones on the path to 5G. For example, LTE-Advanced carrier aggregation was a major deployment trend in recent years. Carrier aggregation combines multiple spectrum blocks (each typically 20 MHz) to deliver higher user data rates.
Until recently, carrier aggregation was limited to licensed bands. A newer variant—License Assisted Access (LAA)—combines licensed and unlicensed spectrum, allowing devices to use both concurrently. LAA’s use of additional 5 GHz unlicensed spectrum on small cells and its harmonization of licensed and unlicensed bands reflect the radio-access priorities of 5G and illustrate how 4.5G might function.
LAA brings LTE’s reliability and performance into the unlicensed 5 GHz band (commonly used by Wi‑Fi and other technologies) to increase peak throughput for mobile users. Using a single 20 MHz unlicensed channel can provide speed bursts up to about 150 Mbps, and each additional aggregated 20 MHz channel increases throughput by a similar increment.
The technology implements fair sharing between licensed and unlicensed 5 GHz users. When an LAA-capable device is within range of both licensed and unlicensed LTE coverage, the network identifies less congested portions of the unlicensed spectrum. It then monitors other access point traffic and transmits in brief millisecond bursts in a way that aims to be fair to other users of 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 is based on the principle that Wi‑Fi and LAA users should have equitable access to unlicensed spectrum. LAA leverages licensed spectrum to maintain LTE-grade performance for control signaling and real-time user data with quality-of-service guarantees, while opportunistically using 5 GHz channels for incremental throughput gains.
If unlicensed channels become unavailable, LAA keeps the licensed connection active to preserve uninterrupted app coverage. Operators already use Wi‑Fi to offload cellular traffic and support Wi‑Fi Calling, but user experience can suffer when Wi‑Fi is congested and spectrum allocation is not optimized. LAA addresses these concerns by balancing traffic between licensed and unlicensed bands and efficiently using the 5 GHz spectrum.
Initial LAA deployments focus on indoor environments—where people spend more than 85% of their time and where capacity constraints are often most acute. An Ericsson ConsumerLab study spanning 47,000 respondents in 23 countries found that only 41% of users were highly satisfied with indoor browsing and social networking experiences, dropping to 36% for data-intensive activities like streaming video.
LAA can create a rising-tide effect that benefits all mobile users. Devices that support LAA gain higher peak rates by combining licensed and unlicensed spectrum, while users on licensed-only bands benefit because LAA shifts some traffic off licensed spectrum, freeing capacity. LAA also benefits Wi‑Fi users by promoting fair sharing and more efficient use of the 5 GHz band.
By combining licensed and unlicensed technologies and leveraging higher-frequency spectrum on small-cell architectures, LAA represents a significant milestone toward 5G. It improves app coverage and optimizes spectrum use for all users—an important step in the evolution now called 4.5G.
Should the industry focus on app coverage via “4.5G” before 5G? Let us know in the comments.