MMwave small cells boost capacity tenfold, but where are the use cases?

One of the most discussed aspects of 5G is the New Radio’s ability to work in millimeter wave (mmWave) spectrum in a standardized way. Support for these high frequency bands – such as 26 GHz, 28 GHz and 39 GHz – opens up a vast swathe of underused spectrum to add capacity to 5G networks in future.

It also provides a significant opportunity for small cells. At permitted power levels, these high frequency airwaves support very short signal range, so their main value will be to support dense zones of very small cells, indoors or outdoors, in targeted areas where very high capacity is required.

But what are the use cases which demand such density and capacity, and could not be easily satisfied by midband 5G spectrum such as 3.5 GHz?

A Small Cell Forum paper, part of its recently published Release 10, addresses this question. In the paper, ‘mmw 5G-eMBB use cases and small cell based HyperDense networks’, our experts discuss in detail one of the hottest topics at Mobile World Congress this year. Will all the work and investment that has gone into meeting the challenges of running wireless networks in mmWave bands, in an affordable and deployable way, be justified by real world commercial use cases?

It is clear from the paper’s findings that these business cases rely on three interwined elements – building on existing small cell networks to maximize their ROI; adding new high density zones to support additional use cases; and harnessing mmWave spectrum to do that most efficiently.

This means, the paper argues, that in high-population areas mmWave networks will closely follow existing small cell footprints. By densifying existing small cell grids, it will be possible to hit the targets for the 5G enhanced mobile broadband (eMBB) use case – 100Mbps per user as an absolute minimum, with future peaks reaching as high as 20Gbps – even in heavily populated areas. Adding 5G mmWave small cells is expected to increase the capacity of a given hotzone tenfold on average.

High frequencies can also improve the economics of delivering high bandwidth services to consumers and enterprises. For instance, they can support large MIMO antenna arrays while keeping the antennas to a reasonable size and cost.

There are likely to be mmWave bands which are licensed, lightly licensed and unlicensed, each making its own contribution to the potential 5G use cases (unlicensed or shared spectrum can reduce the cost of dense eMBB, while licensed spectrum will be needed to support some critical communications or high QoS use cases, especially in the Internet of Things).

The paper shows that the first priorities for mmWave 5G deployment are likely to be fixed wireless – for last mile broadband connections and for small cell backhaul. In many cases, because of the propagation challenges of high bands, mmWave small cells will be deployed indoors, using lower band networks for wide area mobility, or outdoors in mesh configurations. For service providers, this approach will often be cheaper than laying cables, and small cells can be targeted specifically at areas where the cost is justified by real demand.

Once deployment of these dense fixed or mobile hotzones is underway, additional use cases and revenue streams will become apparent. The report authors expect a “host of new outdoor solutions” to become affordable and deployable, if they piggyback on the initial dense small cell grid. So fixed and mobile broadband, and small cell backhaul, will make the core business case for hyperdense deployment on their own, but that case will be greatly enhanced by the ability to support applications and specialist service providers in many industries – “from banking, healthcare, manufacturing, transportation, entertainment, communications and media to retail and wholesale”, as the paper puts it.

As well as enabling new or improved connected solutions for current industries, it is conceivable that the combination of hyperdense wireless connectivity and the IoT will form the foundation for completely new industries – as the original Internet did.

There will also be indoor opportunities for hyperdense, mmWave-based networks. Initially, these are expected to be focused on sports and entertainment venues, airports and other indoor areas of high mobile usage. These zones will support new applications to improve the experience of employees and visitors, and will often see the small cell networks integrated with edge computing nodes to support applications that require low latency response and improved interaction with the user. These might include real time content delivery during a sports match, or augmented reality experiences within an airport.

As well as providing a dense grid that will be the foundation for more and more consumer and business services, the authors expect mmWave networks to expand, in their second phase of deployment, beyond city centers and high usage locations. As the ecosystem matures, it will increasingly be attractive to deploy high capacity wireless connections instead of wireline access or backhaul, even in suburban areas; while high capacity small cells could deliver gigabit access in a targeted manner to small rural communities. In the latter case, the bandwidth of an mmWave connection allows for self-backhauling, which radically improves the case for rural broadband.

Future SCF papers will address the architectural and procedural aspects of deploying 5G small cell networks in mmWave spectrum. But this first paper on the subject highlights an important point. Too often, the mobile industry has developed technology for its own sake, and then hunted for a use case. In the 5G era, and especially when it comes to challenging technologies like mmWave radio networks, operators will demand that they prove the use case and the revenue model before they invest commercially. This SCF paper will help in that process, and in so doing, aim to boost confidence in mmWave hyperdense networks, and accelerate their adoption.