Get ready for the 5G service that we’ve been promised – with fast speeds and low latency. RF filters will be critical to attaining performance and mitigating interference issues.
Even before it was repeated by Verizon CEO Hans Vestberg at a recent investor conference, we predicted that 2022 would be the initial year of Wave 2, 5G services.
In fact, in June of 2020, we published an infographic that looked at the state of 5G and declared that the industry was only in Wave 1 of the eventual full rollout, with an underwhelming 20% increase in throughput performance and none of the low latency or network slicing benefits promised by 5G.
We’re predicting that 2022 will be the start of Wave 2 5G in the U.S., where throughput will begin to approach nearly 10 times greater than that of 4G. What’s changed? 2021 saw the auctioning of 5G spectrum in Frequency range 1 (FR1)/C-band. Mobile network operators now have everything they need to build out their networks and offer new services; and they are eager to begin.
What does Wave 2 look like?
Today’s 5G Wave 1 network is only the first step toward services that will be able to deliver more than 700 Mbps to handsets and mobile devices according to our analysis using the Shannon–Hartley theorem. Wave 2 will see the technology evolutions that need to happen to make this a possibility, such as wider bandwidth spectrum, multiple antennas, and the use of real 5G filters that operate to protect these wide bandwidths and mitigate interference from other users. These filters make true 5G performance possible in a fully loaded network. This should enable downloading of a 3GB movie in seconds.
A warning, however - as bandwidth grows, so does interference. Devices that do not have an RF filter designed for 5G networks could lead to data rates that plunge back to 4G speeds.
New spectrum is the main driver of Wave 2
The US led the world in allocation of commercial wireless spectrum prior to 5G, but it has fallen behind other countries in the allocation of “mid-band” spectrum.
C-band frequencies (4GHz to 8GHz) are an untapped set of airwaves that promise to fix the precarious state of U.S. 5G. The FCC recently announced the winning bidders in the C-band auction, which drew over $80 billion in total bids in the US; Verizon and AT&T dominated with a combined license total of approximately $68 billion. Verizon succeeded in more than doubling its existing mid-band spectrum holdings by adding an average of 161 MHz of C-Band nationwide for $53 billion, including incentive payments and clearing costs.
Kyle Malady, CTO of Verizon, said of the auction results: “We secured a game-changing amount of C-Band spectrum to go along with our leadership in millimeter wave spectrum. We’ve been planning for many months, and are already working to make this the fastest deployment of new spectrum ever.”
While carriers can get higher Wave 2 throughput without moving to a standalone architecture (SA), they can’t deliver the low latency and advanced features like network slicing. Therefore, we predict that the move to use the new spectrum will come with a shift to standalone networks in 2022.
What needs to change in the handset
For handsets and other devices to make the leap to Wave 2 5G, they will need to source new filters for their devices. From product tear downs, we know that the Apple iPhone 13 is leading the way with the use of acoustic wave filters for 5G bands. The key features needed for these devices include performance at high frequencies and wide bandwidth, superior power handling, and steep rejection of interfering signals. Filters that support carrier aggregation will also be important which adds a lot of complexity to the filters. The other RF front end change that is required in the base station is the massive MIMO (mMIMO) antenna that will allow signals to travel farther and more efficiently, enabling 5G networks to be overlaid on the existing 4G footprint.
Resolving C-band interference challenges
Before companies like Verizon and AT&T deploy the first tranche of C-band spectrum for 5G, groups in the airline and aerospace industry say the carriers need to put short-term solutions in place to avoid harmful interference – or expect major disruptions to air travel, transport, and emergency helicopter operations.
In August of 2021, 19 groups and companies representing the aerospace and aviation industry met with FCC officials urging the agency to grant a pending petition to reconsider part of the 2020 C-band order and put carrier-initiated steps in place by December 5, 2021, “to ensure aviation and public safety by protecting radio altimeters from harmful interference from 3.7 GHz licensed operations.”
Radio altimeters are key safety-of-life systems used to measure the height of an aircraft above the ground, particularly important up to 2,500 feet depending on aircraft, where harmful interference could cause issues during landing approaches. The FAA believes C-band transmissions could leak into the altimeter frequency range, causing potential safety issues. Prior to the deployment of 5G in mid-band spectrum, there was no potential interference issue, so high performance filters in plane radar altimeters were not needed.
Wi-Fi is another area in which interference may be a major issue. Until recently, Wi-Fi operated in two unlicensed frequency bands - 2.4 GHz (2.401 GHz-2.483 GHz) and 5 GHz (5.170 GHz-5.330 GHz and 5.490 GHz-5.835 GHz). In April 2020, however, the U.S. FCC allocated a massive swath of spectrum for a new unlicensed band at 6 GHz for Wi-Fi 6E. The interference challenge for this Wi-Fi has two distinct elements – interfering signals from incumbents within the unlicensed band, and interfering signals outside of the unlicensed band, which cause noise within the band. The latter issue can be addressed with proper filtering by attenuating potential interferers to a point that they do not generate in-band noise.
This is where new filters designed for 5G Wave 2 technology come into play. Each frequency band in use today needs a filter to keep wanted RF energy in band while keeping unwanted RF energy out. As more wireless traffic takes advantage of 5G and Wi-Fi in the 3 - 7 GHz frequency range, interference between the bands will jeopardize the coexistence of these advanced wireless technologies and limit their performance. Thus, higher performance filters will be required to maintain the integrity of each band.
Wave 2 5G will be a significant achievement and will begin the roll out of new services and capabilities. Of all the changes needed to support these new services, upgrading filters will make the biggest difference.
