The LoRaWAN R1.0 specification recently attained public release status and is now available to download from the LoRa Alliance website.
The alliance and its members, which include many industry leaders and mobile network operators, see this as a major step towards international standardisation in LPWAN (Low Power Wide Area Network), catalysing network deployments and certified sensor manufacturing around the world.
The alliance members have collaborated, sharing knowledge and experience and intensively testing the LoRaWAN R1.0 specification to ensure readiness for the entire ecosystem. It is hoped this will drive the global success of the LoRaWAN LPWANs and guarantee interoperability in one open, carrier-grade global network.
LoRaWAN network architecture is a typical star-of-stars topology in which the gateways are a transparent bridge relaying messages between end-devices and a central network server. 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 generally bidirectional, with support for multicast, enabling software upgrade over-the-air, and other mass message distribution, to reduce the ‘on air’ communication time. Communication between end-devices and gateways is distributed via different frequency channels and data rates. The selection of channel and data rate is a trade-off between communication range and message payload. LoRaWAN data rates range from 0,3 Kbps to 50 Kbps.
To maximise the battery life of end-devices, network capacity and ease of deployment, and to easily scale, the LoRaWAN network server manages the data rate for each connected sensor via an adaptive data rate algorithm. This unique optimisation is based on advanced information such as SNR, RSSI, PER and channels to ensure optimal performance under local radio conditions.
National LPWAN’s for the Internet of Things (IoT) have strict requirements in terms of security for each individual user and typically require local hosting. To ensure this for the user, the application or the network owner LoRaWAN includes a unique network key to ensure security at the network level, a unique application key to ensure end-to-end security at the application level, and a device specific key.
LoRaWAN has several classes of end-point devices to address the very different requirements of almost any kind of IoT application:
Bi-directional end-devices (Class A): End-devices of Class A allow for bidirectional 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 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 are queued automatically 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 synchronised 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.
For more information visit www.loraalliance.org
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