How can we achieve data speeds 10x faster, latency 10x lower, and support a much higher density of simultaneous Internet of Things (IoT) connections in 5G than in 4G? Electronic communications regulators are awarding millimeter-wave (mmWave) spectrum frequencies for 5G deployments to address the challenges and deliver the promises of 5G. Until recently, we have ignored mmWave bands and considered them impractical for mobile-cellular networks.
Now, they are essential to achieve the ambitious 5G performance targets as higher frequencies gain recognition for their utility in densely populated high-traffic areas demanding lots of bandwidth.
4G gave us ride-hailing services and video streaming in mobile devices. The capabilities of 5G mmWave will make multiple new applications that need ultra-low latency feasible, including mission-critical applications such as industrial Internet, smart grids, remote surgery, and intelligent transportation systems (ITS) involving connected and autonomous cars interacting with infrastructure and pedestrians. It will also support new or improved applications that require very high speeds, including next-generation consumer applications such as the streaming of ultra-high definition (8K) video and 3D video, and the development of virtual and augmented reality applications. Much more is under development and testing in the labs of R&D centers and start-up ventures where researchers and entrepreneurs are pushing the limits of the newest mobile technology.
mmWave will play a key role in enabling these new applications. Technically, mmWave refers to spectrum frequencies between approximately 24 GHz and 100 GHz, such as 26 GHz, 28 GHz, 37 GHz, 39 GHz, and 47 GHz. Thanks to the large channel bandwidths available in mmWave bands—from 100 MHz to 1,000 MHz–and their short propagation distances, mmWave frequencies are well suited to urban areas and confined locations such as stadiums. Dense urban areas and localized sites demanding the highest performance carry the greatest volumes of traffic. Networks are most likely to experience periods of congestion in these locations.
The high performance of 5G will transform how consumers and enterprises utilize mobile systems. Millimeter-wave spectrum bands are essential to delivering the increased data speeds, reduced latency, and supporting the large numbers of connections in dense-urban and high-traffic areas that distinguish 5G from 4G.
However, mmWave bands can’t do it alone. Other spectrum bands that are part of the 5G standard include low-bands (under 1 GHz) and mid-bands in the sub-6 GHz range (where 3.5 GHz has become the first band typically awarded for 5G). These three tiers of 5G bands are complementary in terms of their characteristics and capabilities. The low and mid-frequency spectrum ranges provide coverage over much greater distances but offer slower data speeds than mmWave. They have been occupied to a significant extent by TV and radio signals as well as earlier generations of digital cellular technologies—2G, 3G, and especially 4G LTE.
In contrast, millimeter-wave transmitters cover much smaller areas but can carry substantially more data and support new applications that make the difference between what 5G and 4G networks can deliver. mmWave spectrum bands are required to achieve the increased data speeds, reduced latency, and support the large numbers of connections in dense-urban and high-traffic areas. The high performance of 5G will transform how consumers and enterprises utilize mobile networks. mmWave will be a crucial part of 5G deployments in cities and will play a critical and unique role anywhere network congestion becomes a problem as demand for capacity grows, and established systems become congested during periods of peak traffic demand.
5G mmWave will coexist in an integrated fashion with 5G deployments below 6 GHz. It will also synchronize with 4G LTE in the lower frequency bands during a significant transition period, using technology that enables the sharing of spectrum between 4G and 5G systems. Fast adaptation to changing channel conditions will enable switching within and across cells to help achieve consistent levels of performance and coverage. Dynamic Spectrum Sharing (DSS) will enable 5G systems to coexist with 4G networks in the lower frequency bands to make the transition from 4G to 5G smoother, less disruptive to existing services, and less expensive than it would be otherwise.
The inescapable implication is that mobile operators require mmWave bands to let 5G be all that it can be. Regulators who have yet to release these higher bands should accelerate the processes they have chosen to do so in order to enable the deployment of mmWave systems sooner rather than later.
Martyn Roetter, Director of Research at TechPolis, holds a Ph.D. in Physics from Oxford University and has extensive technology consulting experience.