Millimeter-wave radios have swiftly become the fastest point-to-point radio option on the market due to the huge amount of bandwidth accessible in the 70 and 80 GHz E-Band spectrum.
Millimeter-wave radios have swiftly become the fastest point-to-point radio
option on the market due to the huge amount of bandwidth accessible in the
70 and 80 GHz E-Band spectrum.
Today, radio transmission products with full-duplex data rates of up to 10
Gbps over several kilometers, and carrier-class availability levels are
available. Due to their lower cost, mmWave radios have the potential to
revolutionize business models for mobile backhaul providers and
metro/enterprise “Last-Mile” access connectivity.
What is E-Band?
Millimeter Wave on the E-Band spectrum is a high-speed (up to 10Gbps)
high-capacity wireless communication technology that is excellent for
metropolitan settings. Links can be deployed densely in congested cities
using high frequency microwaves without causing interference, and without
the need to dig for cables and fiber optics, which can be costly, sluggish,
and disruptive.
mmWave links can be set up in hours, and transferred and utilized on
multiple sites as network requirements change.
E-Band distances
Recently, backhaul products operating in the millimeter frequency spectrum
have seen tremendous expansion.
Because theoretical distances are subject to rain attenuation, and different
settings can have different characteristic attenuations, it is vital to
calculate these distances carefully and precisely. The antenna size, channel
size, and availability target all play a role in determining the maximum
transmission distance for 70 - 80GHz radios.
Antenna size: The larger your antenna, the greater the
transmission distance your links can cover.
Channel size: The smaller the channel size, the greater
the maximum transmission distance.
Availability target: This is the level of availability
you need to serve customer expectations.
Due to atmospheric absorption for millimeter waves, the frequency bands used
by the 70 - 80GHz radios are more susceptible to rain attenuation than lower
frequency bands. Cities with more yearly rainfall will, on average, have a
shorter range than cities with drier climates.
Under clear weather conditions, the transmission distances exceed several
kilometers due to low atmospheric attenuation values.
Even under these circumstances, air attenuation varies with frequency. At
lower microwave frequencies, up to around 38 GHz, air attenuation is
relatively minimal, with values as low as a few tenths of a decibel per
kilometer (dB/km). Absorption by oxygen molecules creates a big rise in
attenuation around 60 GHz. Radio transmission distances at 60 GHz are
severely hampered by this huge increase in oxygen absorption.
A broader low attenuation zone opens up beyond the 60 GHz oxygen absorption
peak, where attenuation drops to roughly 0.5 dB/km. This window of low
attenuation is commonly referred to as E-band. The E-band attenuation values
are similar to what conventional microwave radios encounter. At higher
frequencies above 100GHz, air attenuation normally increases, and there are
multiple molecule absorption bands caused by oxygen and water absorption.
E-band frequencies are desirable for high-capacity wireless transmission
because of the low atmospheric attenuation window between 70 and 100 GHz.
As with all high-frequency radio propagation, rain attenuation typically
determines the practical limits on transmission distances. In the presence
of rain, radio systems operating in the E-band frequency range can undergo
significant attenuation, as shown in the diagram below.
The International Telecommunications Union (ITU) and other research
organizations have collected decades of rainfall data from all over the
world. Rainfall characteristics and relationships between rainfall rate,
statistical rain duration, rain drop sizes, and other factors are generally
well understood, and using this information, it is possible to engineer
radio links to withstand even the worst weather events or predict the
durations of weather-related outages on long-distance radio links operating
at specific frequencies.
The ITU rain zone classification scheme shows the expected statistical
rainfall rates in alphabetical order. While areas that experience the least
rainfall are classified as “Region A,” the highest rainfall rates are in
“Region Q.”
By combining the results of rainfall rate vs. attenuation and using the ITU
rainfall charts, it is possible to calculate the availability of a
particular radio system operating in a certain part of the world. You can do
so using the
link budget calculator
provided by Siklu.
Alternative High Data Rate Wireless Technologies
As alternatives to E-band wireless technology, there are a limited number of
viable technologies capable of supporting high data-rate connectivity.
Fibre-Optic Cable
Fibre-optic cable has the most bandwidth of any viable transmission
technology, enabling extremely high data rates to be delivered across long
distances. Despite the availability of thousands of kilometers of fibre
around the world in long-haul and inter-city networks, “Last-Mile” access is
still limited.
Fiber connectivity can be challenging due to the significant and often
prohibitively expensive upfront expenditures of digging trenches and laying
terrestrial fiber, as well as right-of-way issues.
Long delays are also common, not just as a result of the physical process of
trenching fiber, but also as a result of environmental concerns and probable
bureaucratic hurdles involved.
Microwave Radio Solutions
Fixed point-to-point microwave radios in the 4 - 42 GHz band can support
higher data rates, such as full-duplex 100 Mbps Fast Ethernet or up to 500
Mbps per carrier. When compared to E-Band, the spectrum in more traditional
microwave bands is limited, often congested, and typical licensed spectrum
channels are quite small.
The frequency channels available for licensing are typically no more than 56
megahertz (MHz), with the majority being 30 MHz or less. Wide 112MHz
channels with 880Mbps per carrier may be accessible in some bands, but only
in higher frequency bands appropriate for short distances.
As a result, radios running at higher data speeds in these bands must use
highly sophisticated system architectures with modulation methods as high as
1024 Quadrature Amplitude Modulation (QAM).
Because of the complexity of these systems, distances are constrained, and
capacity is still limited to 880Mbps in the largest channels.
Due to the limited amount of spectrum available in these bands, the wider
antenna beamwidth patterns, and the sensitivity of high QAM modulation
towards any kind of interference, denser deployment of traditional microwave
solutions in urban or metropolitan areas is extremely problematic.
Commercially Available Millimeter-Wave Solutions
Highly reliable wireless solutions are available to meet today's high
capacity network interconnectivity requirements, providing fibre-like
performance at a fraction of the cost of laying fiber or leasing high
capacity fiber connections.
In the E-band spectrum, Siklu's product line
offers point-to-point radio solutions with speeds up to 10 Gbps. The systems
are offered in a variety of antenna sizes to satisfy the customer's
availability requirements over precise deployment distances, all at the most
competitive pricing points.
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2023-07-17
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