a unique capability called adaptive data rate (ADR) to
increase transmission distance. This allows the LoRa WAN
network to automatically and independently choose the
most appropriate output power and data rate for optimal
and efficient communications by each device, while
controlling the SNR (signal-to-noise ratio) and link budget.
Devices that are closer to the base station can transmit at
higher data rates, while devices further away transmit at
This transmission model makes it possible to match the
power and speed requirements of a particular application,
rather than using a “one size fits all” approach. By using
different ADRs (SF1 through SF12), devices can transmit
up to 50 Kbps or over distances up to 20 kilometers with
link budgets up to -148 dB.
LoRa’s robust link management scheme enables it to
support lower data rates across even larger distances.
In fact, when researchers set out to determine the limits
of LoRa Technology’s range, they set a world record for
LPWAN packet transmission. The experiment happened
on August 26, 2017, when a high-altitude balloon carrying
a LoRa WAN sensor was released in the Netherlands.
Over the next three hours, the sensor transmitted its
data as the balloon drifted with the wind and rose to an
altitude of nearly 39 Km. During its flight, the sensor’s data
transmissions were received by over 140 different base
stations spread across Europe. The longest transmission
was 702 Km (436 miles) using only 25 m W of transmit
power (see Figure 3).
Because different applications have different
communication requirements, the LoRa WAN specification
also incorporates different “classes” of devices. There are
Class A devices are generally battery-operated sensors
that only need to communicate on an as-needed basis.
Examples include temperature and motion sensors that
send data when triggered by some external anomaly,
such as a high or low temperature or sensed motion.
Additionally, these devices use the “Queen’s Protocol,”
meaning they can only be spoken to after they have first
spoken, i.e., they will
listen for a response after
transmitting. This allows
the sensor application
to notify the sensor not
to transmit again until
a specified time has
elapsed, or to establish
a new “set point” for the
temperature. Class A
devices provide for the
mode, enabling field
deployments of sensor
devices that operate on
the order of tens of years
from a single battery,
albeit with the larger
Class B devices are
also generally battery
operated, but with the
added capability for
Figure 2: The LoRa WAN standard is optimized for both low power
and long distance.
Class A Asynchronous Mode
Class B Beacon Mode
Class C Continuous Mode Table 1: The LoRa WAN standard specifies three device classes.