LoRa? (Long Range) WAN - connecting IoT devices

One of the key challenges in building out the Internet of Things is ensuring that all those “things” are able to communicate over the Internet. The number of IoT devices is massive—25 billion devices by 2020 and any network that supports that communication has to scale to handle the traffic. This implies, there are problems for the network, and there are problems with the IoT devices themselves because they run on battery power, have weak radios, and have limited memory and processing power.

IoT devices today pick from several technologies to support their communications like Wi-Fi but it uses lots of energy and transmits lots of data which is not much useful for IoT devices which don’t have energy to spare and usually send limited data in small quantities. There are also limitations on the number of devices a single Wi-Fi router can handle and they can run out of capacity as the number of IoT devices in a home increases. Bluetooth lets devices communicate, but only over a limited range. Like Wi-Fi, it can also require too much power. ZigBee is low power and transmits over longer distances at low data rates but not all implementations of ZigBee are compatible.

LoRaWAN? is a Low Power Wide Area Network (LPWAN) specification intended for wireless battery operated 'Things' in a regional, national or global network. LoRaWAN targets key requirements of Internet of Things such as secure bi-directional communication, mobility and localization services. The LoRaWAN specification provides seamless interoperability among smart Things without the need of complex local installations and gives back the freedom to the user, developer, businesses enabling the roll out of Internet of Things.

LoRaWAN network architecture is typically laid out in a star-of-stars topology in which gateways is a 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 generally bi-directional, but also supports operation such as multicast enabling software upgrade over the air or other mass distribution messages to reduce the on air communication time.

Communication between end-devices and gateways is spread out on different frequency channels and data rates. The selection of the data rate is a trade-off between communication range and message duration. Due to the spread spectrum technology, communications with different data rates do not interfere with each other and create a set of "virtual" channels increasing the capacity of the gateway. LoRaWAN data rates range from 0.3 kbps to 50 kbps. To maximize both battery life of the end-devices and overall network capacity, the LoRaWAN network server is managing the data rate and RF output for each end-device individually by means of an adaptive data rate (ADR) scheme.

National wide networks targeting internet of things such as critical infrastructure, confidential personal data or critical functions for the society has a special need for secure communication. This has been solved by several layer of encryption:

? Unique Network key (EUI64) and ensure security on network level

? Unique Application key (EUI64) ensure end to end security on application level

? Device specific key (EUI128)

LoRaWAN has several different classes of end-point devices to address the different needs reflected in the wide range of applications:

? 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.

LoRa un-Limits the IoT

The growth of the Internet of Things is limited by the network’s capacity, by the devices’ ability to function without battery changes, and by the ability to encrypt confidential transmissions. The features built into LoRa provide all these capabilities, and will enable the widespread growth of IoT.