Low–Power, Wide-Area Networks (LPWAN) are projected to support a major portion of the billions of devices forecasted for the Internet of Things (IoT). LoRaWAN™ is designed from the bottom up to optimize LPWANs for battery lifetime, capacity, range, and cost.
What is LoRa ?
LoRa® is the physical layer or the wireless modulation utilized to create the long range communication link. Many legacy wireless systems use frequency shifting keying (FSK) modulation as the physical layer because it is a very efficient modulation for achieving low power.
Chirp spread spectrum has been used in military and space communication for decades due to the long communication distances that can be achieved and robustness to interference.
LoRa is the first low cost solution open to the public.
What is LoRaWAN ?
LoRaWAN™ defines the communication protocol and system architecture for the network while the LoRa® physical layer enables the long-range communication link. The protocol and network architecture have the most influence in determining the battery lifetime of a node, the network capacity, the quality of service, the security, and the variety of applications served by the network.
In a LoRaWAN™ network nodes are not associated with a specific gateway. Instead, data transmitted by a node is typically received by multiple gateways. Each gateway will forward the received packet from the end-node to the cloud-based network server via some backhaul (either cellular, Ethernet, satellite, or Wi-Fi). The intelligence and complexity is pushed to the network server, which manages the network and will filter redundant received packets, perform security checks, schedule acknowledgments through the optimal gateway, and perform adaptive data rate, etc.
In order to optimize a variety of end application profiles, LoRaWAN™ uses different device classes
The device classes trade off network downlink communication latency versus battery lifetime.
Bidirectional terminals with a planned reception window
Bidirectional terminals with a continuous listenning
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.
This Class A operation is the lowest power end-device system. Downlink communications from the server at any other time will have to wait until the next scheduled uplink.
In addition to the Class A random receive windows, Class B devices open extra receive windows at scheduled times.
This allows the server to know when the end-device is listening.
End-devices of Class C have almost continuously open receive windows, only closed when transmitting.
This class has the best latency en terms of bidirectional communication. The down point is the consumption because it is constantly listening. It is recommended to have a power supply for products using the class C.
It is extremely important for any LPWAN to incorporate security. LoRaWAN™ uses two layers of security: one for the network and one for the application.
The network security ensures authenticity of the node in the network while the application layer of security ensures the network operator does not have access to the
end user’s application data. AES encryption is used with the key exchange using an IEEE EUI64 identifier.
LoRaWAN principal advantages :
Low consumption and battery autonomy
Robustness against interferences
Network load capacity (Number of connected devices)