In the telecoms industry all roads have been leading towards 5G for some time now. However, it’s safe to say that 5G mobile technology is still many years away from commercial deployment. Whilst 5G mobility specifications and use case debates rage on, mobile service providers aren’t standing still on the current 4G connectivity standard and are rapidly introducing 4.5G and 4.9G technology to differentiate their networks.
Meanwhile, in the untapped fixed wireless space, with little legacy or complicated requirements slowing progress, 5G fixed will likely become the preferred internet delivery alternative to costly fiber-to-the-home. However, there is still an ongoing debate as to which is the best approach to take to tackle the challenges of reaching unconnected homes.
Testing the viability of mmWave spectrum
In 2016, there was a concerted effort to raise the profile of the high-frequency mmWave spectrum (above 24GHz), to prove its viability with 5G players. Verizon has begun tests using the 28GHz spectrum after the FCC opened it up for commercial use, in addition to a number of other frequency bands including 70GHz. However, the viability of these bands should be scrutinised for both mobile and fixed applications, and whether integrating handset and home solutions in common infrastructure and spectrum makes sense at all.
There’s no doubt that millimeter wave (mmWave) spectrum has been proven as successful for point-to-point infrastructure links that have total line-of-sight, as demonstrated by companies such as Webpass, which was acquired by Google. However, delivering mmWave broadband connectivity in non-line-of-sight (NLOS) environments, such as suburban areas, is extremely problematic over the last quarter mile. This is because signals can be affected by environmental factors such as foliage. This is typically found in suburban areas, where almost 80 percent of the U.S. citizens reside. In higher frequency bands weather can also negatively impact signal propagation, disrupting connectivity.
Service distance between links can be reduced, but this is more costly and the obstacles that disrupt mmWave frequencies still remain. ISPs face a dilemma: there is a need to provide connectivity over long distances, which can penetrate foliage, however with limited availability of mmWave line-of-sight links, this frequency will not deliver.
Connectivity in sub-6GHz spectrum
Fortunately there is an alternative. Rather than using limited mmWave channels, ISPs should switch their focus to re-using the sub-6GHz spectrum encompassing both unlicensed and various licensed spectrum which are better suited for fixed wireless propagation in neighbourhoods. Over 14,000 wireless ISPs globally have quietly proven in rural areas that the sub-6GHz bands are extremely effective at delivering fixed wireless services at long distances. Plus, unlike the relatively high costs of high frequency 28GHz, sub-6 GHz costs come in below $100 per subscriber, making it a cost effective alternative.
These bands have traditionally been considered out of bounds because there is less spectrum available when compared to mmWave bands. However, new spectrum reuse GPS technologies are emerging which can coordinate transmissions across a network. This makes it possible to run an entire network on only two operating channels. Interference between signals can thus be avoided with spectrum recycled across dense geographic areas.
Massive MIMO technology can also help to solve interference by using a large number of antennae at the base station, serving many users in densely populated areas, while staying within the confines of the spectrum. This results in considerable cost savings; the current cost of subscriber equipment in the mmWave spectrum can be more than seven times that of sub-6GHz equipment, which is already in use today. This new wireless architecture is poised for large scale use in high density neighborhoods for multipoint deployments for the first time.
The wireless answer for 5G
The standards for 5G have yet to be defined in the mobile realm, but this has not deterred ISPs and vendors, which have already begun testing the technology in order to influence its introduction. Early tests from Verizon, AT&T, US Cellular, and Nokia in North America suggest that whereas 4G was a pure mobile play, 5G will initially be deployed for fixed wireless applications.
Fixed wireless provides high-performance connectivity that can be established and scaled at ease, at a low price point. It is the obvious choice for commercialising 5G within a strict timeframe. The next step for the industry is to define which wireless bands are most appropriate for fixed wireless applications.
Trying to create an efficient 5G fixed infrastructure is a key target for the telecoms industry. The major fiber and wireline players, such as Verizon and AT&T, are now focusing on 5G fixed wireless so they can also start offering gigabit internet services nationwide. By observing the different spectrum in a variety of deployment environments, operators can now see the way in which the licensed mmWave spectrum can be unsuitable in terms of cost and usability. From this evidence, the potential use of the sub-6GHz spectrum is clear, especially when providing connectivity in built-up areas. The amount of research which is being conducted within the industry, it is safe to say that we are moving rapidly closer to creating and effective 5G infrastructure which will, in the not too distant future, serve all environments efficiently on a global scale.
Jaime Fink is Co-Founder and Chief Product Officer at Mimosa, a provider of cloud-managed, hybrid fiber-wireless networks.
Filed Under: Telecommunications (Spectrum), Wireless