Rethink non-line-of-sight
Real-performing networks require
real-performing backhaul.
Ericsson has proven that
Wireless Fiber (MINI-LINK) in
traditional frequency bands
outperforms traditional non-lineof-sight (NLOS) solutions.
New Backhaul Challenge
Wireless connectivity is a reality
in enterprise today. As users
require more access to mobile
technologies, networks become
denser, more complex and IT
managers face challenges with
backhaul. Add to that topography
and environmental dynamics, and
direct line-of-sight (LOS) does not
always exist between nodes.
Common methods to compensate
for lacking LOS include passive
reflectors and repeaters or even
daisy chaining. These are not
always effective resolutions to the
challenge and creates a need for
near- and non-line-of-sight
(NLOS) microwave backhaul.
Ericsson Research has
performed a study
comparing a Wireless
Fiber (MINI-LINK) system
working at 28 GHz and a
traditional NLOS system
working at 5.8 GHz,
looking at how the
systems perform in
different NLOS situations.
Breaking the Myth
The traditional belief in the
telecom industry is that sub-6
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GHz frequencies are required to
ensure performance in locations
where NLOS conditions exist.
One problem is that the available
spectrum below 6 GHz is very
limited and is insufficient for
certain types of backhaul.
To test this belief, Ericsson
evaluated two test cases:
1 Reflection
2 Diffraction
In the reflection case, a link with
100 meters hop length was set up
with a reflection in the wall of a
building. A stable throughput of
400 Mbps was measured with the
28 GHz system, while the 5.8
GHz system showed a
degradation to 70 Mbps due to
multi-path fading.
In the diffraction case, a link
was set up with a 150 meter
hop length, diffracting the
signal on the edge of a
building and down to street
level. The 28 GHz system
had a maximum throughput of
400 Mbps even with a 30
degree diffraction angle, while
the 5.8 GHz system showed
more than 50%reduction in
throughput in the same
diffraction angle.
With this study, Ericsson has
proven that Wireless Fiber in
traditional frequency bands,
above 20 GHz, outperforms
traditional NLOS solutions.
The myth is crushed,
and there is a need to
rethink NLOS for the
enterprise
NLOS Principles
As illustrated in Figure 1, all NLOS propagation scenarios make use of one or more of the following
effects:
Diffraction
Reflection
All waves change when they
encounter an obstacle. When
an electromagnetic wave hits
the edge of a building,
diffraction occurs – a
phenomenon often described
as the bending of the signal. In
reality, the energy of the wave
is scattered in the plan
perpendicular to the edge of the
building. The energy loss –
which can be considerable – is
proportional to both the
sharpness of the bend and the
frequency of the wave.
Reflection, and in particular
random multi-path reflection,
is a phenomenon that is
essential for mobile
broadband using wide-beam
antennas. Single-path
reflection using narrow-beam
antennas is, however, more
difficult to engineer owing to
the need to find an object
that can provide the
necessary angle of incidence
to propagate as desired.
Figure 1
Penetration
Penetration occurs when
radio waves pass through an
object that completely or
partially blocks line of sight. It
is a common belief that path
loss resulting from
penetration is highly
dependent on frequency,
which in turn rules out the use
of this effect at higher
frequencies. However,
studies have shown that in
reality, path loss due to
penetration is only slightly
dependent on frequency, and
that in fact, it is the type and
thickness of the object itself
that creates the impact on
throughput.
For example, thin, nonmetallic objects – such as
sparse foliage (as shown in
Figure 1) – add a relatively
small path loss, even for high
frequencies.
In traditional LOS solutions, high system gain is used to support
targeted link distance and mitigate fading caused by rain. For
short-distance solutions, this gain may be used to compensate for
NLOS propagation losses instead. Sub- 6GHz frequency bands
are proven for traditional NLOS usage, and using these bands is a
viable solution for enterprise backhaul. Contrary to common
belief, but in line with theory, Wireless Fiber microwave backhaul
in bands above 20GHz will outperform sub-6GHz systems under
most NLOS conditions.
The key system parameter enabling the use of high-frequency
bands is the much higher antenna gain for the same antenna size.
With just a few simple engineering guidelines, it is possible to plan
NLOS backhaul deployments that provide high network
performance. And so, in the vast amount of dedicated spectrum
available above 20GHz, microwave backhaul is not only capable of providing fiber-like multigigabit capacity, but also supports high performance backhaul for enterprise, even in locations
where there is no direct line of sight.
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Real Performance
Realize It
Backhaul is a key element in creating highperforming networks. Limited capacity can result
from inadequate backhaul regardless of the
investment in the corporate network. Ericsson
Wireless Fiber allows you to avoid impact to
your user experience with greater spectral
efficiencies and capacity.
Wireless Fiber is designed for hops over
several miles, with a superior system gain in a
very narrow beam. By using these capabilities
in very short hops and by using the
environment in a smart way, diffraction and
reflection can be used to overcome
obstructions between buildings and network
infrastructure. The throughput will be very high
and stable, ensuring your enterprise stays
connected in the most challenging
environments.
High-performing NLOS solutions enable
businesses to optimally deploy their network
infrastructure based on what works best in the
radio environment.
Because of Ericsson’s efficient NLOS Wireless
Fiber solutions, organizations can achieve 4
to 6 times more capacity in backhaul
compared to traditional NLOS solutions.
With all of this in place, you can create a
network that performs the way your business
needs it to – we call it Real Performance.
For more information about this study, additional resources are available:
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YouTube Video: Dispelling the NLOS Myths
Ericsson Business Review: Non-line-of-sight microwave backhaul for small
cells
To learn more about Ericsson Wireless Fiber and other enterprise
solutions, please visit us at
www.ericsson.com/us/connecting-business
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