For maximum LoRaWAN range: Positioning gateways and sensors correctly

Radio connections are to be used more and more frequently for data transmission, as they enable flexible handling of end devices and save the time-consuming laying of cables. However, despite long-range wireless technologies such as LoRa, the connection between sensors and gateways can be unstable.

Lost data packets or shortened battery life of wireless sensors are often due to poor wireless connectivity. This, in turn, is often due to the incorrect handling of gateways and antenna or poor positioning and lack of knowledge about the propagation of signals. To help you avoid the most common mistakes and get the maximum range and stability out of your LoRaWAN, we’ll explain some basics and give tried-and-tested tips.

You can find more information about the advantages of the technology and areas of application in the field of IoT at LoRa Funk.

LoRa Reach in Theory and Practice

In the manufacturer’s specifications of LoRaWAN modules or in general information about LoRaWAN, a range of 15km is usually specified. However, this is only a rough estimate under very good conditions. For example, if there is a line of sight, no obstacles in the radio link and flat terrain.

Have you even read about 50km or 70km LoRa range? This is indeed possible, but under conditions that are unrealistic for most applications: the gateway is mounted at a height of at least 100m, there is a line of sight, there is absolutely perfect, atmospheric conditions and the sensor is also placed higher than its surroundings.

In real environments, such as industrial halls or office buildings, such ranges are not possible. Depending on the conditions, a range of 200m to 500m is possible in buildings and up to 5km in outdoor areas (company premises, etc.).

What antennas and donuts have in common

With the help of antennas, signals are known to be sent and received, or to be more precise: electromagnetic waves are emitted and detected. This capability is not uniformly developed in antennas in every direction. Depending on the type of antenna, it transmits and receives better or worse in certain directions. This is described by the term radiation characteristics.

In the most commonly used antenna form, the rod antenna, the emitted waves propagate in a donut-shape. As a transmitting antenna, it radiates most of the power to the side, but only slightly upwards and downwards.

Since the characteristics of an antenna apply equally to both transmitting and receiving, the donut model is also used for the detection of signals: on the side of the antenna it receives very well, above or below rather poorly.

Optimal positioning of gateways

The radiation characteristics of the antenna must be taken into account when positioning the gateway. In the following considerations, a rod antenna is assumed.

Indoor use on one level

If sensors are to be received on one level (e.g. in a hall, one floor, etc.), the LoRa antenna must be mounted vertically on the gateway. The location should ideally be in the middle of the area to be covered.

According to the antenna characteristics, it seems that the top sensor cannot be received by the gateway because it is not in the covered area of the antenna. However, the signal from the sensor will be scattered and reflected on the walls, so some of the signal will arrive at the gateway antenna.

Indoor use across multiple levels

If you want to cover several levels or floors with a gateway, the gateway should be placed in the middle of the building and, as can be seen in the figure, the gateway antenna should be aligned horizontally (!). The radio waves propagate mainly upwards and downwards on the basis of the given antenna characteristics (donut-like). In this way, all floors are covered in the best possible way.

Gateway outside the building

Another option is to place the gateway outside the building and align the antenna vertically. In this way, several floors can be “transmitted” horizontally from the outside. This benefits from the lower damping of the windows compared to concrete/reinforced concrete false ceilings.

Outdoor positioning

Outdoors, it is important to ensure that the gateway is installed at a sufficient height and that nothing is obscured by anything in the immediate vicinity. The higher the gateway is positioned, the farther the LoRa connection reaches. So the ideal would be a free-standing mast on which the gateway is mounted.

However, the height must be chosen relative to the distance of the sensors, as it is not possible to receive ideally directly below or not in the radiation cone of the gateway.

Since the gateway cannot always be installed free-standing, another elevated position should be chosen (e.g. roof, balcony, window on the upper floor). Of course, shading by buildings, walls or the like must be taken into account. In the direction of shading, the reception performance is limited.

If possible, a line of sight between the gateway and the sensor should be sought to achieve the best possible connection. However, signals can also be received via scattered paths (via detours), but these are greatly attenuated.

Assembly of gateway and sensors

The range of sensors/gateways can be significantly increased if a few basic rules are observed. Any object directly in the vicinity of a transmitter has a negative effect on the transmission behavior. The smaller the distance from the object to the sensor/gateway, the greater the effect on the transmission behavior, as the radiation is attenuated by it.

If sensors or gateways are mounted directly on walls, the following should be observed to optimize the range:

• Do not mount the sensors/gateways directly on the ground. A mounting height of min. 1.5m serves as a guideline.
• Mount the sensors/gateways at a distance of 20cm from the wall.
• If the obstacle, e.g. a wall, has an opening (e.g. window), it is best to place the devices there.

Building a LoRaWAN in a Challenging Environment

If you want to set up a LoRaWAN in a difficult environment and cannot change it, there is always the possibility of strategically positioning several gateways so that the entire area can be covered. Since modern LoRa gateways can transmit the sensor data to an IoT platform via LTE, the installation and operation of multiple gateways is also possible easily and cost-effectively.

In addition, special LoRaWAN nodes help to visualize the transmission strength and with which the area to be covered can be measured. In this way, areas can be identified at an early stage where another LoRaWAN gateway is needed to establish a nationwide network.

For more information, please do not hesitate to contact us!