What is LoRaWAN?

LoRaWAN is a Low Power Wide Area Network (LPWAN) specification created for wireless, battery-operated devices. LoRa is already deployed in millions of sensors, according to the LoRa-Alliance. Some of the main components that serve as the foundation for the specification are bi-directional communication, mobility and localization services.

One area where LoRaWAN differs from other network specs is that it uses a star architecture, with a central node to which all other nodes are connected and gateways serve as the transparent bridge relaying messages between end-devices and a central network server in the backend. Gateways are connected to the network server via standard IP connections while end-devices use single-hop wireless communication to one or many gateways. All end-point communication is bi-directional, and supports multicast, enabling software upgrades over the air. According to the LoRa-Alliance, the non-profit organization who created LoRaWAN specifications, this helps preserve battery life and achieve long-range connection.

A single LoRa-enabled gateway or base station can cover entire cities or hundreds of square kilometers. Of course, range depends on the environment of a given location, but LoRa and LoRaWAN claims to have a link budget, the primary factor in determining communication range, greater than any other standardized communication technology.

End-point classes

LoRaWAN has several different classes of end-point devices to address the different needs reflected in the wide range of applications. According to its website, these include:

• Bi-directional end-devices (Class A): End-devices of Class A allow for bi-directional communications whereby each end-device’s uplink transmission is followed by two short downlink receive windows. The transmission slot scheduled by the end-device is based on its own communication needs with a small variation based on a random time basis (ALOHA-type of protocol). This Class A operation is the lowest power end-device system for applications that only require downlink communication from the server shortly after the end-device has sent an uplink transmission. Downlink communications from the server at any other time will have to wait until the next scheduled uplink.
• Bi-directional end-devices with scheduled receive slots (Class B): In addition to the Class A random receive windows, Class B devices open extra receive windows at scheduled times. In order for the End-device to open its receive window at the scheduled time it receives a time synchronized Beacon from the gateway. This allows the server to know when the end-device is listening.
• Bi-directional end-devices with maximal receive slots (Class C): End-devices of Class C have nearly continuously open receive windows, only closed when transmitting.