August 2017 53
30 to 50 meters is possible. SIGFOX sells the hardware
technology and sets up networks to operate and maintain.
Ingneu. Ingenu does not use the lower frequencies
as do the other long range standards. It uses the popular
2. 4 GHz band. It gets its long range capability by using its
own special modulation technique called Random Phase
Multiple Access (RPMA) that is a form of direct sequence
spread spectrum (DSSS) with differential BPSK. It also relies
on low data rates, special coding techniques, and highly
sensitive receivers to achieve wide area coverage. Ingenu
also builds and operates their own networks.
Weightless. Weightless is a group of long range
wireless technologies specifically targeting Io T and
M2M applications. It is an open family of specifications
with different capabilities fitting a variety of use cases.
Weightless N, for example, is a simplex (one way) standard
for sensor monitoring. It uses the less than 1 Gbps ISM
bands for long range using differential BPSK. With low
speeds, it can achieve a range of up to 5 km.
Weightless P is the two-way standard. It uses low data
rates of 200 bps to 100 kbps, and GMSK or offset QPSK
modulation to reach out about 2 km. An interesting version
is Weightless W that uses the TV white space spectrum;
unused 6 MHz TV channels in the 470 to 790 MHz range.
With wide channels, data rates up to 10 Mbps are possible
at a range up to 5 km thanks to the low frequencies. All the
Weightless standards are available royalty free.
Wi-Fi. Standard Wi-Fi like 802.11n/ac or other current
versions are not really long range technologies. Their
advantage or benefit is very high speeds with multiple
users. However, some special versions of Wi-Fi have been
created for long range work. These are the IEEE 802.11f
and 802.11h standards. The 802.11h version is referred to
as HaLow. It uses the 902-928 MHz ISM band. Modulation
is OFDM with BPSK, QPSK, or QAM to achieve data rates
up to 1 Mbps. Range can extend to a kilometer or more
even with low power.
The 802.11f version (like Weightless W) uses the
TV white space frequencies. Known as White-Fi, this
standard can produce data rates of up to 24 Mbps in a 6
MHz channel. Range can be up to 10 miles if the lower
frequency TV bands are used. These new standards are not
widely utilized yet, but are expected to be more attractive
alternatives as the Wi-Fi Alliance gets certification programs
Cellular. Perhaps an unexpected technology for Io T
projects is the current fourth generation (4G) cell phone
standard called Long Term Evolution (LTE). It is generally
considered to be too complex and expensive for simple
sensor monitoring and like applications. On the other
hand, Io T’s close relative M2M technology has used older
2G and 3G cellular networks for low speed applications,
and especially for its relatively long range (several
kilometers) capability. Now, new LTE versions designated
Category 0 and 1 are available to address the needs of Io T.
One of the new LTE versions is called LTE-M. Instead
of using a full 10 or 20 MHz LTE band, it only occupies 1.4
MHz. This greatly simplifies the radio, yet it can achieve a
data rate of up to 1 Mbps and uses very low power. It uses
the standard LTE network for communications.
Figure 2 shows an LTE-M radio module for embedding
in Io T or M2M products. It is ublox’s SARA-R410M LTE
Cat M1 module. It operates in any one of four LTE cellular
A second version is called NB-Io T. This standard uses a
narrow band (NB) of only 180 kHz and even lower power.
Data rates to 250 kbps can be achieved. Both LTE-M and
NB-Io T use OFDM but with more limited modulation
choices to keep power consumption low.
Both of these new LTE versions fit a wide range of
uses. Radio module prices are reasonable so can be readily
incorporated into other products or systems. Just keep in
mind that you do need to pay for access to the cellular
network with a service contract.
Watch for increased use of these technologies as the
field of Io T grows. Even newer standards are likely to show
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