| How
far we've come
The convenience of connecting devices without the
use of wires has led to the unprecedented success of wireless
technologies in the consumer sector. Due to this success,
these same technologies are beginning to appear in various
other settings including industrial applications. Wireless
technologies offer a number of key benefits including mobility,
flexibility, wide coverage, and cost savings.
- Mobility and efficiency
Improved data communication leads
to faster and more efficient transfer of information between
people in your organization as well as between you and your
customers. Members of your sales team, for example, can
remotely check stock levels and prices while on a sales
call.
- Flexibility and easy
relocation or expansion
In a factory setting, stationary
systems can be connected over a wireless network to mobile
subsystems or robots to achieve a level of connectivity
that would otherwise be impossible. Furthermore, wireless
technology can make it much simpler to gain temporary access
to plant machinery for diagnostic or programming purposes.
- Saving time and money
Wireless networks can be easier
and cheaper to install and implement than wired networks.
There is no need to purchase meters and meters of wire or
to pay additional installation costs to wire your environment.
The average time required to deploy a wireless solution
is also significantly shorter than for a wired solution.
However, the range of a standard
802.11 wireless network today is only 100 to 300 meters. Although
this may be good enough for a home or small office environment,
larger businesses, industries, and outdoor field applications
(such as a minefield) can require a range of 500 meters or
more. Consumer-grade solutions and most wireless access points
on the market just aren’t able to provide that kind of coverage.
To expand your wireless range, you would need to purchase
repeaters or additional access points, leaving you with a
hefty bill. But fear not, cost-effective and long-range solutions
are in the works.
Pushing
the boundaries
Although users could use power amplifiers or higher
gain antennas to increase their wireless signal strengths
for a longer range, these methods require more time and financial
investments on the part of the user. Moreover, using an amplifier
means more noise will be received, which decreases performance.
In real case testing, we found that amplifiers do not improve
long distance transmission by much. Non-standard solutions
for long-range wireless also include using licensed frequency
bands and proprietary radio technology. However, the throughput/data
rate for proprietary radio technology is not high enough for
industry-grade demands. Instead, it would be preferable to
use a wireless access point that already has a coverage range
of 500 meters or more. A promising method wireless hardware
manufacturers are exploring to extend wireless transmission
ranges is protocol optimization.
Wireless transmissions today are based
upon the IEEE 802.11 protocol stacks. By modifying these stacks,
wireless solution providers can optimize them for long-range,
point-to-point applications. Modifying the stacks may not
be completely compliant with 802.11 standards but it is sometimes
necessary to adjust the protocol parameters to achieve long
distance transmission. In fact, the University of California
at Berkeley's TIER
project is currently using this method to bring wireless
Internet access to widely dispersed rural communities in developing
countries. This is similar to the technology Moxa uses to
provide our AWK-4121
wireless AP/bridge/client with a transmission distance
of up to 10 km.
Going
the distance
Protocol optimization also allowed Moxa to provide
one of our clients with long-range wireless coverage to clear
a minefield. Removing land mines for military or humanitarian
purposes is a dangerous undertaking. Common ways to detect
mines for removal are to have combat soldiers or armored mine
clearing vehicles sweep the area using metal detectors and
relay the information back to the control center over a wireless
network. This allows the control center to maintain continuous
data and video streams about the minefield, send pertinent
information and warnings to the field site, and keep track
of a vehicle or soldier’s location and status.
However, consumer-grade solutions and
standard wireless access points do not provide a long enough
range to cover the entire minefield, so you would need to
find a way to set up and power multiple access points. This
is not only costly and time-consuming, but also dangerous.
By installing a Moxa AWK-4121
wireless AP/bridge/client with a high gain antenna
at the control center, our client only needed a single device
to create a wireless coverage zone over the entire minefield
for seamless communication with vehicles in the field. In
the future, automated vehicles that can be remotely controlled
may even be deployed to further minimize the risks associated
with mine clearance.
The
upper limits
The enhanced flexibility and freedom of wireless
has helped many businesses and organizations to increase productivity
and lower costs. Even though the 802.11 standard does not
support long distance coverage at the moment, wireless solution
providers like Moxa are already working to improve the IEEE
802.11 protocol stacks for long-range wireless connections
and address issues related to security, reliability, and speed.
With access points, such as the AWK-4121,
that are capable of transmitting up to 10 km, you can expect
to hear more about long-range wireless products going the
distance in the not too distant future.
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