If you are working with networked devices, you may have heard of LoRaWAN at one time or another. It is a long-range network protocol. It enables the networking of things with the Internet even over longer ranges with low energy consumption. This solves one of the big problems that applications within the Internet of Things have faced up to now. With a battery life of up to five years and low maintenance costs for the sensor network, the LoRaWAN can be used for a wide variety of new applications.
This gives you a brief overview of what the LoRaWAN can do. In this article, we look at the architecture, key features of core technology, and the latest use cases where it is used.
What is LoRaWAN Technology?
The great thing about this technology is that it is based on an open standard. It uses an unlicensed spectrum as part of the ISM frequency band (“Industrial, Scientific, and Medical”, German: Industry, Science and Medicine). In Europe, the LoRaWAN uses the 868 MHz frequency range, while in the USA the 915 MHz frequency band is released. By using the unlicensed spectrum, it is very easy to set up and use your own network. Many telecommunications operators are already using LoRaWAN and offer the technology as part of their service offering in numerous countries worldwide. Comcast, KPN, Orange, SK Telecom and many other providers are actively implementing large-scale launches in their markets. This makes LoRaWAN even more interesting as a technology because it is compatible with the networks of different operators – large and small.
The LoRaWAN standard is monitored by the LoRa Alliance, which in turn consists of over 500 members who support the protocol and align many of their components, products, and services with LoRaWAN. These include companies such as MOKOSMART, ARM, Cisco, Microchip, and ST.
What distinguishes LoRa from LoRaWAN?
Let’s start with the definition of LoRa – what is it exactly and how is it different from LoRaWAN? LoRa is a wireless technology similar to more common technologies such as Wi-Fi or WLAN, Bluetooth, LTE, and Zigbee. However, technology often does not cover all requirements, which means that users have to accept compromises. LoRa meets the demand for low-cost, battery-operated devices that can transmit data over long ranges. However, LoRa is not the right solution for the transmission of data over large bandwidths. LoRa is a technology that converts data to be transmitted into electromagnetic waves. This technique is also known as the chirped spread spectrum，it has been used in military and space communications for decades. It is due to the long communication range and the low susceptibility to interference.
LoRaWAN, on the other hand, is the MAC protocol for the network of high-performance LoRa nodes based on the Internet of Things, which cover long ranges and have low energy requirements. It uses the advantages of Lora described above and optimizes battery life and service quality for the LoRa nodes. The protocol is completely bidirectional, which ensures reliable message transmission (confirmation). End-to-end encryption is provided for security and data protection purposes, over-the-air registration of endnotes and multicast functions. The standard also ensures compatibility with LoRaWAN networks around the world.
LoRaWAN architecture mainly consists of four elements:
• End nodes
• Gateway (base stations/router)
• Network Server
• Application server
End nodes are physical hardware devices that are equipped with sensor functions, a certain amount of computing power and a radio module for translating the data into a radio signal. These end devices can transmit data to the gateway and also receive it. Even with a small battery, they can last several years if they are put into deep sleep mode to optimize energy consumption.
When a device sends a message to the gateway, this is known as an “uplink”. The answer that the terminal receives from the gateway is called “downlink”. On this basis, a distinction is made between three types of end devices:
• Class A
• Class B
• Class C
Class A devices have the lowest energy consumption compared to the other two classes. However, these can only receive a downlink if they have sent an uplink. Class A devices are suitable for the transmission of data at time-based intervals (e.g. every 15 minutes) or for devices that send data based on events (e.g. if the temperature rises above 21 degrees or falls below 19 degrees).
Class B end nodes allow more message slots for downlinks than class A. This reduces message latency but is also less energy efficient.
Finally, class C has an ongoing receive window that is only closed when the device sends an uplink message. Therefore, this is the least energy-efficient variant, which often requires a constant current source to operate.
Gateways are also known as modems or access points. A gateway is also a hardware device that receives all LoRaWAN messages from end devices. These messages are then converted into an array of bits that can be transmitted over conventional IP networks. The gateway is linked to the network server that transmits all messages.
Gateways are transparent and have limited computing power. More complex tasks are carried out in the network server. Depending on usage and type, gateways are available in two versions:
Gateways for indoor use, e.g. MKGW2-LW, MOKOSMART.
All messages from the gateways are forwarded to the network server. This is where the more complicated data processing processes take place. The network server is responsible for:
1. Routing/forwarding messages to the right application;
2. The selection of the best gateway for downlink messages. This decision is usually made on the basis of a link quality indicator, which in turn is calculated via the RSSI (Received Signal Strength Indication) and the SNR (Signal to Noise Ratio) of packets that were previously received;
3. Removing duplicate messages when received by multiple gateways;
4. Decrypting messages sent from end nodes and encrypting messages sent back to the nodes;
5. Gateways usually connect to the network server on an encrypted Internet Protocol (IP) link. The network usually includes the commissioning of the gateway and a monitoring interface that enables the network provider to manage gateways, remedy faults, monitor alarms, etc. …
The application server is where the IoT application is located – this is particularly useful for data captured using end devices. In most cases, application servers run via a private or public cloud, which is connected to the LoRaWAN network server and handles application-specific processing. The interface with the application server is controlled by the network server.
• LoRaWAN functions
• Bi-directional communication
A terminal can transmit data to the gateway and also receive it according to the settings. These settings can also be called up within the application.
An interesting function of LoRaWAN is the localization without the need for GPS. This is particularly useful for tracking systems and sensors since it is battery-efficient and can be maintained more cheaply than conventional methods.
LoRaWAN was designed for large IoT deployments in which thousands of devices are networked with a manageable number of gateways. These gateways can monitor multiple channels and process multiple messages at the same time.
Another important property of LoRaWAN is the speed with which data can be transmitted. There are different data rates that can be used for the transmission. These are also called spreading factors (SF). A slower transmission enables a longer and more reliable range.
For example, imagine you are talking to someone who is very close to you. You can speak very quickly in this situation and your counterpart understands everything you say. When you speak to someone who is far from you, you have to speak much slower to be understood. This principle also applies to the LoRaWAN protocol.
Adaptive Data Rate
With LoRaWAN, the network can also automatically optimize the speed at which the device transmits its data. This function is called the adaptive data rate (or ADR) and is particularly important to increase the capacity of a LoRaWAN network. ADR allows us to easily scale the network by adding another gateway. Because of this gateway, many end devices now automatically adjust their spreading factor. As a result, the individual devices are shorter “on the air”, which means more capacity for the network.
The adaptive data rate (abbreviation: ADR) is a simple mechanism that adjusts the data rate according to the following rules:
If the radio signal strength (also called “link budget”) is high, the data rate can be increased;
If the link budget is low, the data rate can be reduced.
It is important for every LPWAN to use a comprehensive security solution. LoRaWAN uses two levels of security: one for the network and one for the application. Network security ensures the authenticity of the end device in the network, while the application level ensures that the network operator does not have access to the application data of end-users. AES encryption is used for key exchange.
The network level is responsible for identifying the node. It checks whether a message really comes from a specific device and is also considered an integrity check. It can also encrypt MAC commands.
The application level is used for the decryption and encryption of payloads.
Both keys are encrypted with 128 bit AES in ECB mode.
Use cases and areas of application
LoRaWAN has found its place on the market in terms of applications and areas of application. Thanks to its unique properties, LoRaWAN is best suited for scenarios like these:
1. Access to electricity (electricity) is limited or restricted;
2. The locations are physically difficult to access or very remote;
3. The number of end devices is significantly higher compared to conventional mobile phone connections;
4. The end devices do not have to send messages continuously.