LoRaWAN Transmits over Long Distances

Sensor Technology with Minimal Energy and Low Cost

LoRaWAN (Long Range Wide Area Network)

LoRaWAN is the MAC layer protocol that controls communication between LoRa-devices and LoRa-gateways. LoRaWAN applications operate in globally and regionally different frequency ranges of the ISM and SRD bands.

In Europe, the frequency band from 433.05 to 434.79 MHz (ISM Band Region 1) and from 863 to 870 MHz (SRD Band Europe) is approved for LoRa communication. In North America, the frequency band from 902 to 928 MHz (ISM Band Region 2) is available for use.

Frequency spreading based on chirp spread spectrum modulation enables high efficiency in data transfer and power consumption. At the same time, the modulation used minimizes interference.

LoRaWAN (Long Range Wide Area Network) belongs to the low-power wide area network technologies (LPWAN). The technology operates in the license free wireless frequency spectrum, usually known as ISM (industrial, scientific and medical) radio band. Due to national legislation, these frequencies can differ regionally.

This technology article is written by Wolfgang Weber, Global Industry Manager at Pepperl+Fuchs

What is LoRaWAN?

LoRaWAN (Long Range Wide Area Network) belongs to the low-power wide area network technologies (LPWAN). It operates in the licence free wireless frequency spectrum, usually known as ISM (industrial, scientific and medical) radio band. Due to national legislations, these frequencies can differ regionally.

The aim of LoRaWAN can be described as a technology which offers wireless transfer of data over longer distances with a minimum of energy and at low costs. The amount of data and the number of transmissions are strictly limited. LoRaWAN is also a mainly uplink oriented technology. It is therefore primarily suited for the transmission of sensor signals with very limited data content (payload) and no real-time requirements.

LoRaWAN provide ADR (adaptable data rate) by changing the spreading factor SF. A low SF leads to a high data rates and vice versa. This has significant influence on the range of the signals. The adaptation of the date rate is performed by an algorithm in the network server, using Received Signal Strength Indicator (RSSI) and Signal to Noise Ratio (SNR) values to evaluate the transmission quality. A higher date rate also saves air-time, which reduces the probability of collisions.

Fill levels of waste containers, glass containers or salt silos

LoRaWAN – due to its long range – enables the integration of sensors into metal containers that dampen radio signals. Fill levels of waste containers, glass containers or salt silos can be monitored and their collection controlled in a centralized system.

The Advantages

LoRaWAN takes advantage of the long range characteristics of the LoRa physical layer, allowing a single-hop link between end-devices and one or many gateways. All modes (class A, B, and C) are capable of bi-directional communication, and there is support for multicast addressing groups to make efficient use of spectrum during tasks such as Firmware Over-The-Air (FOTA) upgrades or other mass distribution messages.

Topology

LoRaWAN is a star transmission technology. The so called end-device sends its data (payload) to a local gateway. The number of gateways corresponds to the required connectivity in a certain area. In a free field the coverage is much better than in a very congested area, especially if end-devices must be reached in the basement of buildings.

The gateway transfers the messages to a server. The so-called LoRaWAN Network- Server (LNS) is handling the communication with the end-devices. Therefore, an end-device can transmit messages via several gateways in the reach of the signal, if they belong to the same server.

The Network-Server incorporates a Join-Server, which is handling the join process of an end-device and the generation of the encryption keys. The Network-Server delivers the messages to an Application-Server, which is usually already part of the end-user infrastructure.

Interfaces

The communication between an end-device and the LNS is defined by the LoRaWAN specification issued by the LoRa Alliance. The payload of the end-device is of course specific to the respective task of the end-device and needs to be decoded. Since there is an end-to-end encryption of the payload, the decoding usually happens on the Application- Server side. But the protocol between Network-Server and Application-Server depends on customer requirements. Typical formats are MQTT or Rest API.

Guidelines for Transmission Time

Since LoRaWAN operates in a licence free spectrum, there are legal limitations. In this case the use of air-time is limited to 1 % in the preference channels. Since LoRaWAN allows for 6 different transmission cycles this leads also to a restriction of the payload. Restrictions and and regulations for the operation of a LoRa-Network differ in Europe and especially in the USA.

Three LoRa Device Classes

The frequencies (ISM band) depend on the region respectively local legislation and rules. Typical examples are: 868 MHz (Europe), 915 MHz (USA), 950 MHz (Japan) and 430 MHz (Asia).

Three Classes of Devices

Class A is primarily up-link oriented. This class can receive down-link information from a server only directly after a sent message. After sending a small message receive window is displayed, which may be used to send messages to the end-device. Class A devices represent approximately 90 percent of the market.

Class B devices can receive down-links in defined time intervals which are independent from the up-link messages. This requires a time synchronization with the server. This version is rarely used on the market.

Class C devices may communicate bi-directionally at any time. As a consequence such units cannot be operated by batteries anymore, since the power consumption is much too high. Therefore, one of the most important advantages of LoRaWAN applications is lost. In application areas where power is available but no wired communication infrastructure is existing, this is an alternative to other wireless communication networks, because of the long range feature.

Spectrum

The base technology of LoRaWAN is called CSS (Chirp Spread Spectrum). That means the radio signals are using an increasing (up-chirp) or decreasing (down-chirp) frequency at a constant amplitude. This method has proven to provide a very good range for the given low power and it can receive messages even under the noise level.

Spreading Factor (SF)

To adapt to different transmission qualities, there are 6 Spreading Factors (SF) available. Spreading means, that the transmission time is expanded to improve the range. A higher spreading factor increase the air-time and allows for a longer range of the signals, but also reduces the data-rate.

Coexistence

LoRaWAN uses the ALOHA principle. ALOHA is a multiple access protocol for transmission of data via a shared network channel. That means, an end-device can send out data any time without synchronization with other end-device or the receiving gateway.

If several end-devices send data at the same time using identical data rates, then collisions may happen and data could be lost.

Using different spreading factors allows the gateway to receive data from different end-devices simultaneously. Additionally, there are different channels available (the three default channels are 868.10 MHz, 868.30 MHz, 868.50 MHz).

From Waste to Flooding

As a result of heavy rainfall, small streams turn into raging torrents. LoRaWAN technology can support flood protection measures.

Waste Management

Waste bins are objects with no electrical supply or wired data connection. Therefore, a sensor must operate autonomously. In this specific case that means a maintenance free operation of up to six years and a radio communication even out of a metal container is required.

These applications are usually restricted to a clearly defined area. A waste collection service is always operating within a fixed area like a city or an industrial park. Therefore, local networks which could easily be scaled according to the specific environmental conditions, are absolutely feasible.

The amount of data is very limited and there are also no real-time requirements. 3 messages per day are usually completely sufficient.

On the other side, a lifetime of the battery of 6 or more years is demanded, since permanent maintenance of the sensors would generate unacceptable costs. In many cases the network is operated by the customer, which means that there are no fees for the transmission of data.

Glass Containers

Especially glass container are often equipped with fill-level sensors to organize the collection of full containers. This reduces unnecessary driving on the one side and avoids anger on the side of the citizen faced with a completely filled container.

Winter Service

Sensors can also measure the fill level of road salt containers. In combination with meteorological data, the measurement data from the salt silos support the optimal management of winter road maintenance.

Flood Protection

Level sensors are attached to bridges over rivers or canals, for example, where they measure the water level. It is particularly interesting to network data calculated by artificial intelligence with LoRaWAN data. The occurrence of floods can thus be controlled and estimated more effectively.

Interview

The Breakthrough Will Come!

Wolfgang Weber, Global Industry Manager at Pepperl+Fuchs explains in an interview with RFID & Wireless IoT Global why LoRaWAN fulfills the requirements for a potent radio network extremely well, but the expectations regarding the number of gateways have not yet been met.
INTERVIEW WITH WOLFGANG WEBER

Wolfgang Weber is a member of DIN NIA 31 (information technology and applications) for over 20 years as well as a delegate to ISO/IEC JTC1 SC31 WG1. In addition, he was involved in the standardization of data matrix and QR codes. In the organization AIM-D, Wolfgang Weber is the director for optical technologies for 20 years and a longstanding member of the barcode working group.

In 1997, he founded the Omnitron AG and was involved in the development of the first stationary data matrix code reader based on smart camera technology. Since the acquisition of Omnitron AG by Pepperl+Fuchs SE in 2004, he is responsible for the field renewable energies as Global Industry Manager.

1. Has the still very young Long Range Wide Area Network technology (LoRaWAN technology) reached maturity?

That's a good question, and I can answer "yes" unequivocally. Even though LoRaWAN technology is only seven years old – the first specification dates back to 2015 – the technology is running smoothly. End devices, sensors and gateways are available and working. The LoRaWAN network has very good coverage and overall LoRaWAN technology is cost-effective.

2. Which application is a real breakthrough?

Smart metering is an application that works really well. With over 2 million end devices and around 40,000 gateways across Germany, LoRaWAN is used nationwide for reading water meters and heat meters. Data can now also be retrieved quarterly via the LoRaWAN networks. This makes it easier to monitor cost developments.

3. For which applications does Pepperl+Fuchs offer LoRaWAN solutions and which products are included?

We offer an ultrasonic sensor for fill level measurement. These sensors have been in use for a long time, especially in industry. What is new is the sending of the measurement data via LoRaWAN radio networks and the extension of the areas of application to smart cities.

The ultrasonic level sensors are installed, for example, on bridges over rivers or canals, where they measure the water level. We are currently setting up a LoRaWAN solution for water level measurement in Wuppertal. Flood control is supported there via LoRaWAN measuring devices. It is particularly interesting to network data calculated by artificial intelligence with LoRaWAN data. The occurrence of floods can thus be controlled and estimated more effectively.

4. Can you describe any other application examples?

In Wuppertal, we deployed 800 level sensors in glass containers on behalf of the Abfallwirtschaftsgesellschaft (AWG). The installation was carried out in 2021. Also since winter 2021, our sensors in Heidelberg have been measuring the fill level of road salt containers.

The city has launched the "Smart Winter" project and is recording meteorological data. This data is supplemented by measurement data from the road salt silos. The aim is to manage winter services optimally.

5. How is LoRaWAN performing in the industrial sector?

Pepperl+Fuchs is primarily represented in the industrial sector with LoRaWAN. We use inductive sensors at a large chemical company from Baden-Württemberg to control the position of levers on valves. The decision-makers in industry want to eliminate problems and minimize weak points. They are interested in solutions.

In industry, they want to increase efficiency, map processes transparently and drive digitization. Since mobile assets or devices cannot be connected with cables, the LoRaWAN sensor is an optimal solution. It can be installed quickly with two screws and can collect data immediately.

6. Are you satisfied with the project developments of LoRaWAN solutions?

LoRaWAN is very well represented in over 150 countries. 4 million gateways and 250 million end devices are in use. That is already a considerable amount. Nevertheless, expectations are high for the technology. And projects – especially in smart cities – are sometimes slow

7. Why do LoRaWAN projects not run as well as expected?

Topics such as "waste disposal" are often extensively debated in the city committees. In my opinion, however, the breakthrough will come, because the wireless networks are there. The hardware works, is available and the entire implementation is cost-effective. So it's just a matter of time. Hydrogen technology has also been discussed for decades and: now the complete breakthrough has happened. The order books are filled for years to come. If partners work well together and the goals are clearly defined, LoRaWAN can be integrated quickly and cost-effectively. The technology has many advantages.

8. Is it true that NB-IOT is also falling short of expectations?

Yes, that is correct. In China, this radio standard is strongly promoted by the government. In this country, however, this technology suffers from the reluctance to implement use cases. As already mentioned, the possibilities for applications are many, but there is a lack of approving decisions.