Semtech Corporation and IBM Research Center in 2015 presented a LoRaWAN protocol (Long Range Wide Area Network) to the wireless technology market. They performed one new open standard net protocol which was more competitive with Wi-Fi and cellular networks. The main advantage of LoRaWAN is deployment of a bidirectional M2M communication with maximum energy efficiency.
The LoRaWAN technology caused a great resonance in the market and influenced on a single standard acceptance for low power networks -LPWAN (Low Power Wide Area Network).
Itself LoRa abbreviation combines a modulation method in wireless LPWAN nets, designed by Semtech and open LoRaWAN protocol.
Non-profit organization LoRa Alliance was established by several famous electronic manufacturers, such as IBM, Semtech, Cisco, Kerlink, IMST etc., and leading telecommunication operators Bouygues Telecom, KPN, SingTel, Proximus and Swisscom in order to support, develop and standardize the new technology. The implementation of this standard provides easy and fast device integration with IoT for individuals or organizations and can be supported by telecom operators.
Developers from LoRa Alliance define LoRa as a modern superior technology in comparison with regular cellular nets or Wi-Fi due to its spread deployment up to 20 km and high speed up to 50 Kbit/sec with a minimal energy use. Thus, the battery AA type lifetime can be sized in many years.
The main features of this technology allow using LoRa devises almost without limits in such spheres as: local or private automation, industry, smart cities, power industry, health care and etc.
What is LoRaWAN?
Structure key elements: end nodes, gateways, network and application server.
End Node — a chain of control units and measuring sensors. The main (implementation) functions are control and measurement.
Gateway/Concentrator — a receiving framework which performs communication between end nodes with further transmission into a transit network via the channel. The most common examples of such networks are: Ethernet, WiFi, cellular networks and similar telecommunication channels.
End devices with a gateway are forming a Star network. This structure type consists of multi channel transceiver devices which are processing signals from one or several channels. Thus, various equal devises provides network coverage and a bidirectional data transmission between end nodes and a server.
Network Server — a control center for network management. It helps to set scheduling, bitrates throttling, analyzing, received data processing and storage.
Application Server — a software framework that provides data gathering from end nodes and remote operation control features.
The LoRaWAN Star network forming communication bridges with a net server through the gateways.
Such architecture implies that the central server and gateways are owned and managed by the operator whereas the end nodes by clients. Thus, the client receives clear, safe and bidirectional data communication.
To provide the maximum security and confidentiality of transmitted data in LoRaWAN global network, the developers use AES-encrypting system at the different levels, such as:
• Unique Network key, EUI64) — at the network layer
• Unique Application key, EUI64 – application end-to-end security
• Device specific key, EUI128.
1. Bi-directional end-devices, Class A. End-devices 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. This Class 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.
2. Bi-directional end-devices, 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.
3. Bi-directional end-devices, Class C. This Class have nearly continuously open receive windows, only closed when transmitting. Such feature allows work implementation with a huge data amount.
According to Semtech, one LoRa-gateway can maintain up to five thousand end devices due to:
• Peculiarity of network topology.
• Responsive data transmission speed and output rating are controlled by the network server.
• Temporary access sharing.
• Frequency division multiplexing.
• Special feature of LoRa-modulation which allows simultaneously demodulation of different speed signals in one frequency channel.
It could be said that coming out of a low-power wireless LoRaWAN technology gave an opportunity to create a global infrastructure with easy network communication and a big amount of connected end nodes. The distinctive advantages are long range, low power, capability for dense urban environments and indoor coverage.