5G: A look at radios and spectrum

For a long time, a single acronym has defined the network. This is one way in which 5G will be different. There will not just be one radio and one new acronym.

Three tall telecommunication towers with antennas on blue sky.
Credit: Shutterstock

In my last piece I wrote about the evolution of mobile standards from 2G through to 5G and the changes in network architecture – and the increase in prevalence of network virtualization – that 5G mobile communications will bring. But there are also some fundamentals that have characterized standards evolution through all generations of mobile communications that will see an upgrade or change in 5G: the radio and the spectrum resources.

So, what about the radio? For so many generations a single acronym has provided the generational definition. In this respect, 5G will be different. There will not just be one radio and one new acronym. There may be several, depending on how we look at it.

The best that can be said today is that there will be at least three Radio Access Technologies (RAT) or modes spanning bands above and below 6GHz. This may be realized in a standalone or flexible “unified” structure. Arguably, it might be said that there will be as many as six, if we are being fair and acknowledge the next-generation unlicensed Wi-Fi initiatives that are already underway (802.11ax, ay, ah). The IEEE has adopted a standalone approach. Cellular may or may not follow. Regardless, this boundary between licensed and unlicensed is only set to become more blurred as we move forward.

Two licensed band cellular definitions are expected below 6GHz. One will be something of an evolution of OFDM purposed for coverage support and optimized in areas such as latency, energy, spectral containment, and of course throughput. The second will be especially tailored for IoT support. It is less likely in my opinion that this will be based on OFDM. OFDM is great for video, but in the IoT world of trillions of randomly occurring access events, its strict synchronization needs render a severe handicap among others.

The third high-capacity solution will be provided above 6GHz in the so-called mmW bands that start around 30GHz. This is probably where the most industry debate is going on at this time. Regardless of the final outcome, which will continue for some years (spectrum is not even allocated yet!), a few common observations can be made. This radio may or may not be based on OFDM. A single carrier-based approach is more likely to be selected. Simply stated, in moving to higher frequencies and narrower beams, many of the benefits of OFDM such as MIMO integration and higher-order QAM schemes diminish and further PAPR (power) becomes a handicap. So, it is fair to expect something new here as well.

The move to 5G will be a profound and exciting transition for the mobile telecom industry. When it emerges into the mainstream circa 2020+ the business models and processes that will accompany it may well be more aligned with those used in IT circles today. This will be an adjustment for an industry used to a familiar way of working. Beyond technology, this is what will make 5G different. 5G will be about nothing less than an industry transformation.

So, with only a few weeks until Mobile World Congress, where I am sure we can expect to learn a lot more about what everyone is thinking about 5G, the mobile future looks bright. In this post I have just scratched the surface on 5G and its many elements. In future posts I will dig a lot deeper into all of these areas and more, including looking at some specific projects that are pushing the limits of research.

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