LoRaWAN outdoor gateways are often placed in poor conditions. Moreover, in order for the gateway to better collect uplink data sent by nodes, and to issue instructions to nodes better, and to cover more nodes, LoRaWAN outdoor gateways are often used. The gateway is placed in a high position, which brings about a lightning hazard. Lightning may cause damage to the gateway, such as surge damage.
1. Common layout of LoRaWAN outdoor gateways
The common layout of LoRaWAN outdoor gateways is in a high place in the required area. Due to the high position, lightning protection needs to be paid attention to during the layout process.
Lightning protection measures for LoRaWAN outdoor gateways need to be comprehensively arranged both outdoors and indoors.
2. Lightning Protection Outdoor
2.1 Antenna Ground
It is recommended to install an antenna feeder arrester on the N-type connector of all antennas (LoRa, LTE, Wi-Fi and GPS antennas).
The antenna-feed arrester needs to be grounded reliably. It is recommended to use a 10 AWG or better grounding wire, and connect the threaded end of the arrester to the common grounding point of the outdoor building.
When purchasing an antenna-feeder arrester, you need to pay attention to the connection type of the interface (the interface is divided into male and female). The connection type needs to be compatible with the connector on the antenna and the gateway shell.
2.2 Gateway grounding
To ensure reliable grounding of the gateway, it is recommended to use another 10 AWG or better grounding wire to connect the grounding screw at the lower right corner of the gateway housing to the common grounding terminal of the outdoor building.
3. Lightning Protection Indoors
The main strategy for indoor lightning protection is to set up an indoor surge protection system.
In order to protect the indoor equipment and circuits connected to the LoRa gateway, you need to install an Ethernet interface SPD arrester at the entrance of the network cable into the room. All indoor equipment should be protected by this arrester.
Be sure to connect the ground wire end of the arrester to an appropriate building ground so that your PoE injectors and network switches/routers are protected from surges.
Things to look out for include:
(1) Make sure that all antennas (the lightning arrester rating of the GPS antenna is different, as shown below), the gateway housing and the Ethernet SPD are reliably connected to the ground point.
(2) Make sure you provide a well-grounded pole with a lightning rod for the LoRa antenna and gateway device.
(3) The lightning rod should be high enough, and all equipment should be protected by the lightning rod at an angle of 45 degrees.
4. Lightning protection equipment installation
4.1 Installation of antenna feeder arrester
The antenna feeder surge protector is connected in series between the antenna feeder and the transceiver equipment to prevent and reduce the damage to the transceiver equipment due to induced lightning strikes, surge overvoltage and surge overcurrent. It is suitable for 50 ohm RF systems with operating frequency of DC-2700MHz and transmission power less than 200W.
4.2 GPS antenna arrester
The GPS antenna arrester is a surge protection device, which is connected between the GPS antenna and the GPS receiver to prevent and reduce the damage to the transceiver equipment due to induced lightning strikes, surge overvoltage and surge overcurrent.
5. How does the LoRaWAN outdoor gateway connect to the Internet?
The LoRaWAN outdoor gateway is a core hardware component in the LoRaWAN IoT architecture through which data can be collected from devices and forwarded to a network server. It can be said that there is no LoRaWAN IoT network without a LoRaWAN outdoor gateway.
Like other gateways, LoRaWAN outdoor gateways also need to work on a specified operating frequency. When deploying gateways in specific countries, the LoRa Alliance regional parameters must be followed. However, there is no universal frequency, and each country has different laws regarding the use of unlicensed MHZ bands. For example, the LoRaWAN frequency band in China is CN470 (470-510MHZ), while those in Europe and the United States are EU868 (863-870MHZ) and US915 (902-928MHZ) respectively. Each country has its specific channel. For details, you can refer to the regional parameter file of the LoRa Alliance.
LoRaWAN outdoor gateways and devices must be on the same frequency schedule to operate. If the LoRaWAN device uses a different frequency plan than the LoRaWAN outdoor gateway, the device will not be visible to the gateway. In this case, the LoRaWAN outdoor gateway has no way to forward the device data to the network server.
In terms of construction, a LoRaWAN outdoor gateway is mainly composed of two components: the host and the concentrator. The first component, called the host, is the brain of the LoRaWAN outdoor gateway. It's actually a tiny computer that forwards packets to a web server. The key software running in the host is called the packet forwarder and it decides which web server will accept the packets collected by the LoRaWAN outdoor gateway. The second component is the concentrator. It is the RF (radio frequency) part of the LoRaWAN outdoor gateway, and has an RF chip in its front-end part, which can receive data at the same time. There is a digital baseband chip on the concentrator that performs digital signal processing on the RF signal to make it meaningful to the host. The host and concentrator of the LoRaWAN outdoor gateway communicate over serial at the board level.
Depending on the requirements and constraints of the IoT application, LoRaWAN outdoor gateways can be deployed online or offline. For an online gateway, it needs to have a backhaul network to connect to the Internet, and its communication backhaul can be WiFi, Ethernet, cellular, etc. The gateway connected online mainly uses the LoRaWAN network server deployed in the cloud. When the LoRaWAN outdoor gateway is deployed offline, it can use the built-in network server of the LoRaWAN outdoor gateway itself, or connect to the network server deployed locally on the PC or server. In this case, regardless of whether the gateway is online or offline, it must register with the LoRaWAN web server and then set the packet forwarder appropriately.
The LoRaWAN outdoor gateway looks complicated, but in fact it is just a "middleman" between the device and the network server. Its first job is to receive packets by choosing the appropriate frequency plan, which of course matches the needs of the equipment in the region where it is deployed. The second job is to correctly forward the data to the web server, during which the LoRaWAN outdoor gateway is registered with the packet forwarder. With these fully configured, it is possible to have a working LoRaWAN outdoor gateway in no time.
This article introduces the lightning protection measures that need to be paid attention to in the actual use of the LoRaWAN outdoor gateway, including indoor measures and outdoor measures, hoping to help those who use the LoRaWAN outdoor gateway for the first time.
