Having been in R&D for years, 5G is just now getting close to emerging into real wireless networks. Despite the hype, there's still plenty of work to do and improvements to make. Initial 5G deployments and products will likely use just a small portion of its intended capabilities. Standards will evolve, components will improve over time, and networks will need to adapt to the expected higher data rates and use cases. Thomas Cameron, Director or Wireless Technology at Analog Devices, has been at the forefront of 5G development, having given presentations on the state of the technology for a few years now. Aspencore Senior Technical Editor Martin Rowe spoke with Cameron for an update. (He used his cell phone because it works better than his IP phone.)
Rowe: What's the status of 5G standards?
Cameron: 3GPP Release 15 is almost done, there are a few drops (additions) remaining. The Non-Stand-Alone spec came out in 2017 with the stand-alone spec released in June 2018. Updates will include dual connectivity, the ability to simultaneously support LTE and 5G New Radio (5G NR). (Ed note: "Stand alone" refers to all 5G; "non-stand-alone" refers to a hybrid of 5G and LTE.) Download links will likely have both LTE and NR, possibly in the same frequency band. The uplink, however, is causing a problem for handsets and thus it may not have dual connectivity. Handsets may not transmit using 5G NR, at least not at first. Release 15 has provided SoC makers such as Qualcomm and Intel with what they need to get baseband processors out the door. Parts are sampling now, which should enable the first 5G handsets to be available in 2019.
Editor’s Note: After perhaps a decade in research labs and drawing boards, 5G is on the verge of deployment. Indeed, early deployments of the technology are coming online now. You can tell because the marketers have sunk their teeth in and started promoting it. With 5G moving out of the lab, the team at Aspencore looks at what it will take to reach full deployment — from technical, supply chain, carrier, and policy perspectives.
Rowe: What do you expect in terms of "late drops" in Release 15?
Cameron: Don't expect to see anything else regarding base station radios in Release 15. Late drops will likely have more to do with the higher network layers and protocols.
Rowe: What can we expect from 3GPP Release 16?
Cameron: Release 16 will follow the same path as Release 15 in that there will be an initial release that gets us going, followed by enhancements. Release 16 will start with mobile V2x communications. Currently, there's a lot of work being done around channel models dealing with moving, scattering, and reflectivity conditions. That's important, especially in urban environments where you have a lot of vehicles.
IoT is another aspect of Release 16, which should make IoT communications more efficient. Examples include wake-up features and simplified signaling. Release 16 will also focus on reliability and latency.
I don’t expect Release 16 will make changes to the RF side of the radio, but there could be enhancements to the baseband side and some software upgrades.
Rowe: What's the Release 15 pushback from the handset makers?
Cameron: It's an issue in the lower frequency bands. If, for example, you have a 20 MHz channel and you'd like to have 10 MHz of LTE and 10 MHz of 5G NR and you want the two adjacent to one other, that puts a higher demand on the power amplifier (PA) because it looks like a multi-carrier signal. That increases the peak-to-average ratio. We sometimes think of 5G NR as operating in millimeter wave (mmWave) frequencies, but 5G NR can operate at any frequency. T-Mobile has announced a plan to deploy 5G NR in the 600 MHz band <https://www.t-mobile.com/news/first-600mhz-5g-test>. Other operators will probably put 5G NR into their current 3G spectrum.
In cases where carriers will co-locate 5G NR and LTE in adjacent bands, they may even dynamically allocate bands to LTE and 5G NR. Having the two radios on adjacent bands is a problem for handsets only, not for base stations. You will need a more linear PA in the handsets to handle that.
Rowe: Will control functions be handled by LTE and data handled by 5G NR?
Cameron: In the case of non-stand-alone, that's correct. NR will handle data only. The radio-access networks (RANs) will be modified first to handle 5G NR, but the data packets will route to the 4G core network. Over time, a 5G network core will roll out, which will result in a true 5G stand-alone network where the 5G core controls the 5G RAN. That's opposed to a non-stand-alone network, which uses a hybrid of 5G and 4G technologies.
Once 5G uses mmWave signals, there will still be a lower-frequency (sub 6 GHz) "anchor" to handle data when there's no mmWave service available. mmWave service will likely be used only when available and needed. Connectivity will be constant in sub 6 GHz bands.
Rowe: What kind of improvements do you expect in the components going into 5G designs?
Cameron: There will be constant revisions and upgrades to radio designs, just was we've seen with 3G and 4G. Design Changes will reduce complexity, reduce power consumption, and so on. Radios in the sub-6 GHz band are mature now, though they will continue to evolve. The activity is now in the mmWave frequencies. We are still early in the game.
If you look at the mixed-signal portion of the 5G NR, getting the 1 GHz bandwidth requires a fairly high-performance data converter. Data-converter designs will continue to improve. Power consumption will continue to improve as well. The digital engines needed to process data in a 1 GHz channel is impressive. Still, I think it will take some time before we can do massive MIMO at mmWave frequencies. Ten years ago, we would that thought massive MOMI would be impossible even at frequencies below 6 GHz, but it's possible with today's technologies. The PAs are not very efficient, but they will improve.
Rowe: People are holding onto their handsets longer, so how will 5G enter the consumer market?
Cameron: There are always a few early adopters, and I believe that "flagship" high-end handsets will be the first to integrate some form of 5G radio. For example, Sprint will start by using its 2.5 GHz spectrum with 5G NR <http://investors.sprint.com/news-and-events/press-releases/press-release-details/2017/Sprints-25-GHz-Spectrum-Included-in-Non-Standalone-3GPP-5G-NR-Specification/default.aspx>. mmWave handsets will come later. That's one of 5G's features where there's plenty of work left to do.
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