LoRa is the way to modulate a radio signal for high energy efficient transmission of low speed data over long distances. The technology was patented by Semtech company who develops and manufactures transceivers for end devices and chipsets for gateways. Currently available components and devices are working in unlicensed ISM bands (EU 868/433 MHz, US and Japan 915 MHz, Asia 430 MHz), that allows to build a networks without special licenses or permissions for radio frequencies.
LoRaWAN is the open standard for high energy efficient long distance wireless networks (LPWAN – low power wide area networks). The standard can be used to build both public (service provider) or private (corporate) networks of any size. Thanks to ultra-low power consumption of end devices and easiness of deployment, LoRaWAN networks are widely used as a transport layer for IoT networks.
The LoRaWAN standard is developed and supported by LoRa Alliance, a non-commercial association with more than 420 members to date – large hardware and software vendors, service providers, etc. Devices from different vendors can interop in the same network, that effectively removes a vendor lock and, thus, makes the standard attractive for the end customers.
The LoRaWAN architecture is simple and was created with virtualization in mind. That makes a network rollout easy, allowing users, even for without special knowledge in radio networks, deploy the networks based on it.
LoRaWAN networks are suitable for data collection in smart city, agriculture, industrial and other areas where battery powered end nodes with long range radio are needed. Thanks to symmetrical bidirectional data transmission, LoRaWAN networks can be used not only for data collection but for the remote control of various objects, allows remote configurations and firmware management for the end nodes.
LoRaWAN network devices can be divided to three classes: A, B и C.
Class A devices are battery powered devices with focus on long battery life. A typical class A device periodically transmits and rarely receives the data. Devices are allowed to receive the data only during special time window that opens right after data transmission. Some typical examples of a class A devices are metering devices or sensor nodes.
Class B devices are balanced between battery life and the possibility to transmit something to the device. Usually it is a battery powered actuators or beacons. Class B devices open the receive window by schedule, that allows commands to be transmitted to the device.
Class C devices are always receiving the data, except periods of time when they transmit the data. Usually, class C devices have stationary power. A multicast technology (same data packet is received by many devices simultaneously) is supported by the class C devices. That feature allows class C devices to be used in group control systems, such as street lighting systems.
A LoRaWAN network consists out of gateways, end nodes and a network server.
Gateways are responsible for a connectivity between wireless end nodes and a network making the information exchange between radio environment and a network server possible. Gateways are usually equipped with omnidirectional antennas and can cover up to 2.5km in urban environment or up to 10km line of sight radius. They communicate with a network server using a VPN tunnel over the Internet. No any specialized backhaul is required which makes possible to use any wired or wireless Internet connectivity, even the cellular one.
A LoRaWAN network server manages all network components including parameters like transmission power and speed, allowed time on air etc. It organizes the data exchange with end nodes and provides an API to the external applications.
The data transmission speed can be adjusted in accordance of the distance between end node and a gateway. That mechanism increases the gateway’s coverage and allows effective usage of the spectrum.
Data, transmitted over LoRaWAN networks, are protected on both network and application layers.
Network security layer provides end node authorization and authentification of packets on both end node and network server sides.
Application security layer provides AES128 encryption for transmitted data. The encryption keys can be static, preprogrammed in end node and a network server, or dynamic, generated during end node connection to the network.
Two layers of security can guarantee the data safety for the users even in case of data transmission over the LoRaWAN service provider network.