What’s now and what’s next for 5G

-May 17, 2017

Mobile carriers the world over are evolving their networks toward 5G to keep up with the continually escalating demand for data. There is so much marketing blather mixed up with discussion of the technology, however, it can be difficult to track how the industry might get there from here. That’s especially true because, due in part to marketing blather, it’s not clear where here is.

With that in mind, the senior technical staff at Skyworks, led by Skyworks CTO Peter Gammel, recently published a paper called “5G in Perspective: A Pragmatic Guide to What’s Next.”
The drive to 5G has a clear impetus. Improving network performance leads to greater customer satisfaction, which encourages more usage (typically of video content), leading to escalating demand, forcing carriers to implement the next network upgrade. The opening chunk of Skyworks’ report relays some of the evidence for that. Where networks are well-established today: most wireless service providers are chasing the market, not leading it.

So where is the industry now? Skyworks quotes from a 2016 Global mobile Suppliers Association (GSA) report that of 708 mobile networks surveyed globally, only 147 (or 20%) support LTE Advanced features such as carrier aggregation (CA) and multiple input multiple output (MIMO) layers. Of the 147, 102 could support peak download speeds as fast as 300 Mbps. The authors provide evidence that peak rates are rarely achieved, and that average rates tend to be significantly lower–anywhere from 10× lower to 100× lower.

The fastest growth in the industry over the next few years is going to be in the 4G market. There is a defined roadmap for the ongoing evolution of LTE, with roughly one new release version coming every year through at least 2021, including improvements that will eventually constitute 5G. Thus far, each release included step improvements, such evolving signal modulation technology from 16 QAM to 64 QAM to 256 QAM. The most recent release to be commercialized is Release 13.

Release 15, scheduled for 2018, will introduce a grab-bag of technologies new to commercial cellular wireless, however. Usually lumped under the heading “new radio” (NR), they include millimeter wave radio, beam forming, spectral efficiency waveforms, lower latency, multiple numerology, and non-orthogonal multiple access. They are all going to add levels of complexity.

5G standards have yet to be established (they’ve yet to be fully formulated), but Skyworks–like many other companies – expects that gigabit-per-second speeds will be a defining feature. Skyworks also reviews the several fundamental techniques available for increasing data rates: carrier aggregation (CA); moving to more advanced modulation to increase the number of bits per symbol (e.g., using QPSK and moving to higher orders of QAM); and moving to higher orders of MIMO.

Wireless network operators can improve CA, modulation, and MIMO in nearly any combination (on both the downlink and uplink sides) so different networks all based on Release 14, for example, are unlikely to have the same characteristics. Another factor that will also have an effect on network performance is the distance between callers and base stations, Skyworks points out.

That’s what’s going on now, according to Skyworks, and it sets the foundation of its expectations of where the industry is going.

“[T]here will be significant activity in the sub-6 GHz frequency domain. Both 4G LTE as it is currently practiced, and 5G NR will be deployed concurrently in spectrum below 6 GHz. Second, the devices, techniques, and general radio protocols will be very familiar to those addressing this segment of the market. In other words, below 6 GHz we expect the same look and feel with respect to the RF content with allocations for additional content to meet new bands and 5G features,” the company reports.

“So far, 3GPP has decided to tether 5G NR to the existing 4G LTE environment. As such, we do not expect standalone 5G NR devices to exist in the market for quite some time. The implication here is the framework for mobile devices remains on a steady track, albeit with some increased functionality, for the new 5G,” Skyworks continued.

While there’s a lot of excitement about the opportunities created by opening up millimeter-wave (mmWave) spectrum, that isn’t going to be happening right away. There are just too many simultaneous technical challenges. “Currently, there are many obstacles to overcome that would prohibit mmWave deployment in consumer devices as a first step in the technology roadmap. These include battery life, beam tracking and management, and radio propagation challenges, to name a few,” the company states.

The paper dives into some of the nitty-gritty details, including the device technologies still to be developed, mapped against the spectrum used.

All this points to the first opportunities being in the sub-6 GHz spectrum, with fixed wireless. Skyworks states this is in precise agreement with what Verizon Wireless is planning. One of the well-known prerequisites for expanding into mmWave is that cell density will have to increase significantly–more, smaller cells will be necessary. Other considerations include the necessity for backhaul capacity to be increased.

One of the key takeaways is that “what’s next” is going to be different from market to market, from use case to use case, from carrier to carrier. For example, Skyworks notes, the markets driving the most rapid growth in wireless networking are going to be markets with emerging economies, specifically India, the Asia-Pacific region, China, and sub-Saharan Africa. The needs of emerging markets tend to be different from the needs of developed markets.

Though some carriers in developed markets are pushing 5G hard (Verizon, AT&T, SK Telecom among them), Skyworks doesn’t expect the 5G rollout to begin in earnest until 2022. The company believes LTE will still be more predominant globally than 5G at least through 2030.

The full text of “5G in Perspective” can be downloaded from the company’s website.

Brian Santo has been writing about science and technology for over 30 years, for a number of organizations including EE Times, IEEE Spectrum, SNL Kagan, and Light Reading.

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