Open Standard Relays Extend LoRa Networks

Published: December 8, 2023

Semtech has built a solution using LoRaWAN connectivity that leverages battery-powered relays for out-of-reach sensor devices

Companies leveraging LoRaWAN Internet of Things (IoT) connectivity often face a problem on the edge of their networks—a few devices in a remote area out of reach of the gateways.

LoRa technology already sends bidirectional signals at a distance up to 10 kilometers or 6.2 miles, but they can be affected by conditions such as metal barriers. Relay devices extend the distance as well as addressing environmental challenges. While some technology companies have developed such devices to accomplish that, they are proprietary.

So LoRa technology company Semtech has worked with the LoRa Alliance to create its Relay system solution as part of the LoRaWAN open standard. The software and firmware enable communication—to and from—relay devices on any LoRaWAN network.

Collaborative Effort

The system has been tested in the field for collecting water meter data in remote areas in Colorado, using an IoT solution from Arad.

Semtech collaborated with technology companies Actility and Deviceroy for the relay. Actility integrated the relay feature into its ThingPark Wireless and Enterprise network platforms in its latest versions, while Deviceroy built the battery-powered nodes that extend LoRaWAN networks, explains Carlo Tinella, Semtech’s senior product manager, IoT ICs Business Unit.

Water, gas, and electricity metering application providers face stringent service level agreements, and utility users demand cost efficient, but reliable coverage within a geographical footprint.

Reaching Deadspots

While many deployments might accomplish accuracy of tag reads at 95 percent, the missing five percent may be those meters on the edge, such as a cluster of end devices or sensors in a neighborhood that is too small to warrant its own gateway.

Semtech’s Relay chip and software is part of Semtech’s existing LoRa Basics Modem v4 stack, says Olivier Beaujard, Semtech’s senior director of LoRa ecosystems. The addition of extending technology was first discussed among LoRa Alliance members, and the group spent more than a year to come to a consensus on a specification.

Beaujard recalls it was important to the group that they provide open-source software for everyone who wanted to extend their LoRa network reach.

How it Works

Each Semtech Relay can manage transmissions from up to 16 end devices. It is installed within range of a gateway within a network and paired with the LoRa-based end devices, all managed by the network server.

Once in place, the relay uses a channel activity detected (CAD) system in which it is dormant, and wakes up for periods of 25 milliseconds at which time it sends a transmission. If it receives no response it goes back to sleep. If the relay does detect a recognized LoRaWAN end point, it then triggers that device to transmit, receives its transmission, forwards it to the nearest gateway, then goes back to sleep.

One common use case could be extending a LoRa network into a metal insulated container or freezer, or behind a thick wall, according to company officials.

For example, a refrigeration unit could have LoRaWAN-enabled temperature sensors inside it. The relay inside or near that container could then forward data to the nearest gateway where it could then be sent to a server through the network.

LoRa Transmissions to Satellite

The relay can provide a bridge for satellite connectivity as well. Devices in a home could send their data to the relay which would provide direct connection to a satellite system. In fact, there is discussion underway to begin testing the application by transmitting relay data to satellites.

To employ the relays, companies who have LoRaWAN networks in place would have to upgrade the codes for software and firmware embedded on their LoRa endpoints and gateways, while the hardware itself would not need to be replaced.

“You would just change the firmware on a water meter with a new code that is publicly available,” Tinella says.

The relay’s battery life would be seven to 10 years depending on how many devices are being managed by it, and how many bytes of data are sent daily. They are low-power enough that they could be powered through energy harvesting, for instance with the help of a photovoltaic panel. That could increase the flexibility and the versatility of many deployments, the company reports.

Key Takeaways:
  • Semtech teamed with Actility, Deviceroy and Arad to develop an entire solution leveraging new relay devices to extend the reach of LoRaWAN networks.
  • The technology is intended for a small number of sensor devices that are outside the perimeter of an existing gateway network.