Introduction#

One of the most important performance metrics for an IoT application is maximum usable range. Practically speaking, this refers to the maximum distance at which messages can be received without a loss of information. The achievable range is impacted by many different factors:

• Hardware influences, including:

  • Antenna physical parameters (size, shape, directivity, gain)

  • Battery physical parameters (size, capacity, load current, and so on)

• Propagation attributes of the radio signal (carrier frequency, humidity, obstacles, and so on)

• Transmit power

• Receiver sensitivity

To maximize usable range, when developing the Long Range (LR) profile Silicon Labs targeted the last item above, receiver sensitivity, which is affected by multiple input parameters:

• Frame length: The amount of data to be transported

• Data rate: The timeframe available to transport the data

• Data rate offset tolerance: How much the data rate can change during reception

• Frequency offset tolerance: How severely the carrier frequency can vary during the reception

• Selectivity and blocking: Robustness against interferer signals

Though many paths can be taken to improve RX sensitivity, Silicon Labs avoided hardware changes and instead focused on radio configuration modifications. This reliance on PHY development insulated the Long Range profile from additional external hardware dependencies, making the LR PHY benefits available to a broader selection of applications.

The construction of these PHYs is detailed in Using the Long Range Profile in Simplicity Studio 5 provides instructions on evaluating the Long Range Profile using new Silicon Labs development tools and hardware. Measured Performance of the Long Range PHYs reviews real-world measured performance with the LR PHYs.