Page 20 - EE Times Europe March 2022

20 EE|Times EUROPE

OPINION | 5G
filtering is a requirement to keep signals sep-
Why EU 5G Success arate, with full performance once user traffic
saturates the network. To receive the available
5G frequencies along with Wi-Fi and other
Will Require RF Filter wireless technologies, such as ultra-
wideband, a 5G handheld device must have on
the order of 100 filters.
Those filters support 5G spectrum, includ-
Innovation ing sub-6 GHz and millimeter wave, along
with older cellular wireless technologies and
Wi-Fi, Bluetooth, Global Positioning System
By Mike Eddy, Resonant Inc. (GPS), and more. A full filter set is needed for
each antenna in the mobile device. Without
filters, antennas will pick up unintended
The evolution of Europe’s 5G strategy will build demand for signals, degrading performance and eroding
new generations of RF-filtering technologies to channel signals the 5G advantages. Filters allow devices to
without degrading performance. separate the signal bands neatly, channeling
The European Union has established a sound 5G strategy that the desired wavelength from each antenna to
demonstrates how 5G can be implemented in a way that taps the be processed appropriately.
technology’s potential efficiently across the continent.
Europe has defined three “5G pioneer bands,” or harmonized To fulfill the full potential
bands to be deployed across the continent at three frequency ranges.
The low band, in the 700-MHz range, provides longer-range commu- of 5G, the No. 1 priority is
nications. The ultra-high band, of about 26 GHz — within the millimeter-wave range — carries
vast amounts of data over very short distances. The intermediate band is a high-frequency band a radical widening of the
of about 3.6 GHz, sometimes called the Golden Spectrum Band because it provides significant available bandwidth — a task
data speeds over a large coverage area.
This enables a wide variety of use cases. The ultra-high–frequency band is ideal for sports and that requires deployment of
concert venues, where live video streaming might be needed. The low-frequency band is optimal
for rural areas, providing coverage over a broad area, albeit with a lower data rate (see figure). more frequency ranges.

NEXT STEP: OPEN UP THE SPECTRUM
Europe has moved slowly in licensing and assigning spectrum, which has impeded progress in Filters are one of the most prevalent front-
rolling out 5G, despite the well-designed strategy. The Covid pandemic and ongoing political and end components in any mobile device. Typical
trade disputes with Chinese equipment maker Huawei have caused some of the delays. However, filters are on the order of 1 mm and 0.3 mm
2
all of these circumstances are improving. thick, but the sheer number required, which
The continent is still in the first wave of 5G, based on non-standalone networks that leverage continues to increase, poses device design
4G frequencies, and is not yet experiencing 5G’s promised improvements in speed and latency. challenges to reduce size while improving
With today’s 5G network, users can expect the download time for a 3-GB movie to be about performance.
24 minutes, barely faster than the 29 minutes it takes on 4G. When 5G’s full potential is avail-
able, expect it to take less than half a minute. THE RIGHT FILTER FOR THE JOB
The missing piece is new spectrum. To fulfill the full potential of 5G, the No. 1 priority is a There is no one-size-fits-all filter technol-
radical widening of the available bandwidth — a task that requires deployment of more fre- ogy, but most mobile RF filters are based on
quency ranges. In addition, other enhancements, such as beamforming antennas and moving RF acoustic waves generated via the piezoelectric
points of presence close to the users, will improve 5G coverage. effect. Surface acoustic wave (SAW) filters,
initially developed for 2G, are also used in 3G.
RF FILTERING: WHAT IS IT AND WHY DOES IT MATTER? Other technologies, including
Once the spectrum is available, the next key enabler of Europe’s 5G strategy is new RF filter temperature-compensated SAW (TC-SAW)
technology to protect the precious bandwidth from harmful interference. Precise coexistence and particularly bulk acoustic wave (BAW),

The EU’s pioneer bands and how they relate

MARCH 2022 | www.eetimes.eu