A Low-Power Wide-Area Network (LPN or LPWA or LPWAN) is a network designed for sending small amounts of information long distances without using much power, for example uploading data wirelessly from remote sensors or automated meter readers or which are battery powered, solar powered or even use energy-harvesting techniques. There are several different proprietary / public LPN protocols competing for use as the Internet of Things (IoT) develops and Smart products, Smart Homes and Smart Cities become more advanced, one of the key ones being LoRaWAN developed by the LoRa Alliance.
LoRa operates in the sub-GHz band and is designed for communication over distances of several kilometres in suburban environments. It has been developed specifically as an IoT protocol, with a focus on sending secure bidirectional messages in a network over a wide area between up to 1 million ‘Things’.
A LoRaWAN network is typically configured in a ‘Star of Stars’ topology, with multiple end devices (customised sensors etc) each communicating securely to a Gateway in a single hop using the LoRa low power spread-spectrum protocol. Multiple Gateways then each communicate securely via IP (Ethernet / 3G / WiFi) to a central Network Server, which collates the data and also controls the characteristics of the network such as varying the data-rates in the LoRa links to optimise power consumption and network traffic (data rates range from 0.3 kbps to 50 kbps).
LoRa end point devices are categorised into three classes: Class A devices consume the lowest power and only ‘listen’ (receive) for short periods immediately after transmitting data; Class B devices have scheduled listening periods, time-synchronised with a beacon from the gateway; Class C devices are the most power-hungry and are constantly listening when they are not transmitting.
LoRaTM is a trademark of Semtech Corporation.