The Use of High Frequency Spectrum and Fixed Wireless Technologies in 5G
Previously, I published a piece on how small cells are important for 5G. This week, let’s look at a couple of other distinguishing technological enablers of 5G — the use of high-frequency spectrum and fixed wireless. Both of these technologies will work hand-in-hand to provide high-speed internet to the home and on the go, replacing existing technologies like cell towers and cable connections with faster and more advanced options.
High Frequency Spectrum
Also known as millimeter waves, or extremely high frequency bandwidth (EHF), this previously underused territory of the radio continuum offers significant benefits for 5G transmission that aren’t available at lower frequencies. This is largely because millimeter wavelengths can pack a whole lot more data into one signal.
While an LTE 4G transmission might include three channels of 20 MHz, 5G with high frequency waves can sustain up to 8 channels of 100 MHz each, or 800 MHz of total data. This is because the higher up you go on the radio spectrum, the higher the range of frequencies and the greater the throughput. Think of it in terms of a city highway — when two lanes are added to a congested stretch of interstate, the end result is both the potential for faster driving as well as greater capacity. For the average consumer, that means videos load faster, online services work more efficiently, and the user experience is much more satisfying. With applications hogging more and more bandwidth, users need all the help they can get.
Additionally, the high frequency spectrum also creates an explosion of available bandwidth, which was one limitation its predecessors suffered. “The amount of bandwidth available at mmWave frequencies is enormous compared to the amount of frequency spectrum used by 4G and previous wireless network technologies.” And this additional bandwidth will be utilized by the billions of IoT devices enabled by 5G.
Higher capacity also means lower latency. This equates to more seamless transmissions and fewer disruptions for next-gen immersive experiences like VR, AR, and autonomous vehicles.
At the end of the day, you could almost think of the capabilities of high-frequency radio as a package deal. More, faster, and better. All these advantages come from the nature of millimeter waves and what 5G network providers will be able to do with them.
Of course, as in most things, the benefits of the high frequency spectrum are balanced by some significant drawbacks. As compared to 4G, 5G has distance limitations. Low frequency 4G waves can travel further than high frequency waves without compromising signal strength. High frequency 5G waves require small cells to be within a few hundred feet of each other, as opposed to the kilometers apart that 4G cell towers can be. That’s why 5G will need so many small cells.
And you can’t just be in the general area of a high frequency small cell to pick up the signal; you have to be in direct line of sight. Unfortunately, this means that common objects like trees, rain, and buildings can severely hinder connectivity. Experts are continuing to work on problems related to the loss of signal path and keeping the signal alive with both indoor and outdoor transmissions. These higher frequencies are just harder to work with than the traditionally used lower frequencies. All these problems are why use of millimeter waves is still early.
Fixed Wireless
One technology that counteracts the limitations of small cells and high frequency spectrum is fixed wireless. Fixed wireless uses antennas fixed to buildings as a bridge that connects the small cells and cell towers outside with a wireless network inside, removing the need for direct line of sight inside fixed buildings.
Prior to advancements in fixed wireless, buildings were wired with physical cables that delivered connectivity over vast physical distances. And, truth be told, the problem with offering connectivity to the home has always been the last mile. This technology reduces our dependence on physical cables, something that certainly meaningfully impacts rural and other areas that are difficult to reach with cables.
From a business perspective, this also allows wireless companies to enter the home Internet market, challenging traditional broadband companies’ dominance in the consumer space. Imagine “cutting the cord” on not just your TV and voice services but also your Internet. Or your in-home data and your mobile data being offered by the same provider and consolidated into one bill. Not to mention the previously outlined benefits of 5G (more, faster, better).
Verizon rolled out fixed wireless to a handful of test markets late last year, though its not without its critics. And AT&T is focusing on reaching rural markets with its product.
Some challenges are apparent for fixed wireless as well. By definition, it’s an offering that’s only available in a fixed location, despite it being wireless in nature. And convincing consumers who already have a functional home broadband connection to switch won’t be easy, even if there are other benefits yet to be realized. Among other topics discussed at an Enterprise IoT Summit 2017 panel on fixed wireless access, deployment costs can only be recouped in areas with dense enough buildings and structures.
And contrary to what you might think, 5G fixed wireless will still need fiber. Line of sight, which is essential for high frequency spectrum connections, will be possible for only a portion of potential customers using existing towers. Getting connectivity to customer premise equipment (CPE) devices so that they can disseminate the signal through 5G wi-fi routers can still require fiber to the 5G base stations.
Conclusion
While there is a lot of buzz about the potential for high frequency radio waves to enable 5G adoption, there is still a long way to go to achieve that potential. Sure, the data capacity is there waiting for us to use, but there are many implementation challenges on our path. Bandwidth and potential coverage may be significant, but 5G with small cells and millimeter waves have limited distance range — and a heavy downpour or broken tree limb could immediately kill a connection. Like any new technology, it may take awhile to work out all the kinks.
On the hand, 5G fixed wireless promises to finally offer a long-sought solution to the “last mile” problem. And it also may play a significant part in the development of smart homes and smart cities to extend fiber’s reach. If the ambitious telcos can convince enough customers to make the switch from fixed wireline to 5G fixed wireless, we may see some increased efficiencies and economies of scale that will make the whole enterprise worth the cost and effort. Time will tell.
