With 5G still five or more years away from commercial deployments, there may be more questions than there are answers right now, but there's still a lot to be said about the emerging network standard.
To shed some light on both the answers and the right questions to ask, Light Reading caught up with Heavy Reading Senior Analyst Gabriel Brown, fresh from attending the Next Generation Mobile Networks (NGMN) Ltd. 's 5G industry event in Frankfurt, Germany. We grilled him on everything from the definition of 5G to its use cases to its challenges and real potential. Read on to find out what he had to say. (See 5G: What Is It & Why Does It Matter?)
On defining 5G: At this stage, there is not a definition of 5G, so we don't know what it is exactly. There is no threshold that you have to pass or not to be so-called 5G defined yet. What's happening at the moment is the industry is gathering and generating performance requirements. Ultimately, 5G will probably be defined through the International Telecommunication Union (ITU) process called IMT-2020 and Beyond. They are looking to have specifications in place in and around 2020. What the industry needs to do is backfill that and actually develop the technology and standards to be ready for 2020. The ITU itself is developing requirements this year and next. So although ITU is in principle the final arbiter, that's not all that useful today because the industry needs to work on this beforehand.
On 5G's use cases: The Next Generation Mobile Networks (NGMN) Ltd. is developing use cases and user experience requirements ahead of standardization, which is a little different from the traditional process. They are talking about things like 300 Mbit/s downlink in the wide area, indoor ultra-high speed access at 1-gigabit per second or performance of 50 Mbit/s everywhere. And there are things like 1-millisecond latency, ultra-reliable communications and IoT at massive scale. I think there will be overlap between 4G-Advanced and 5G -- overlap particularly in use cases and some overlap in the technology.
On the spectrum for 5G: Spectrum is a big deal, of course. It falls into two parts -- sub-6Ghz low bands and above 6Ghz, known as high bands. The higher bands will use centimeter and millimeter wave technologies, and there is a lot more spectrum available. You'll get much higher data rates, but the propagation is poorer. 5G should, in theory, scale across high and low bands. The problem is you need to optimize technologies differently according to the band. Things like massive MIMO works better in high-band TDD systems than low-band FDD.
At the moment it is not clear. If you go to high band, you have all this spectrum and can leverage massive MIMO for high data rates, but others say that isn't as useful in practice. You want to look at low bands to support mobility and things like that. My feeling is there is a lot of hype around the high bands, but the focus, and I'm not by any means certain about this, will end up going on the lower-bands initially… It depends on a lot of factors. It's hard to call. It might be both simultaneously. For the low band 5G needs to be substantially better than 4G-Advanced for operators to adopt it.
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