LoRaWAN Gateways: A Comprehensive Guide

LoRaWAN or LoRa gateways are radio devices that provide bidirectional connectivity between end nodes such as sensors, IoT devices, and the Internet. They operate using Long-Range (LoRa) wireless networking technology and are a key component of Long-Range Wide-Area Networks (LoRaWAN).

Semtech owns LoRa technology, which is developed and overseen by the LoRa Alliance. This alliance includes industry stakeholders that use LoRa chipsets and networking protocols in various applications.

LoRaWAN gateway is a critical wireless networking component for connecting end nodes to the Cloud-based applications that control them. LoRa gateways have been demonstrated to provide a low-cost and reliable solution for IoT connectivity with several proprietary IoT networks using these devices. IoT devices can use cheaper, low-energy LoRa to transmit their data as far as the nearest gateway. The gateways can receive and forward the data using higher energy and bandwidth networking like WiFi, cellular, and Ethernet.

LoRa gateways: Bridge and router for IoT

LoRa gateways can acquire and concentrate LoRa signals transmitted from IoT devices, with a single LoRaWAN gateway capable of supporting thousands of devices. They act as a bridge or router for LoRa-based IoT devices in their vicinity. Their coverage is significant, being able to pick up transmissions from a distance of over 4.8 kilometers (3 miles) in urban areas and 16 kilometers (10 miles) in remote or rural areas free from obstruction. The gateways'  antenna can be upgraded to a long-range LoRa antenna that can receive LoRa signals in one of three unlicensed frequency bands (depending on region) as well as WiFi, cellular, or Ethernet connectivity for onward transfer of received data to the broader network. Any message received is forwarded with duplicate messages deduplicated by the receiving network.

Typical LoRaWAN gateway component

• LoRa antenna

  
  

The LoRa antenna is used to passively capture signals from end nodes and transfer the data via an SMA cable connected to the SMA-female connector on the gateways radio board. Indoor LoRa gateways are typically supplied with articulating dipole antennas with a gain that is 3 dBi or under. These antennas can be detached from the gateway via the SMA connector and replaced with more powerful external LoRa antennas or a short coaxial antenna cable to an outdoor antenna for more excellent coverage.

• SMA connector

Indoor LoRa gateways usually carry an SMA connector (Nb. Helium gateways/miners usually have an RP-SMA connector, so you would use an  RP-SMA cable to connect to the antenna.) The SMA connector is edge mounted on the gateways radio board. Outdoor LoRa gateways almost always carry the larger and more rugged N connector. GPS, WiFi and cellular RF connectors (usually SMA) alongside the LoRa antenna connector.

• Radio board

This PCB provides the paths for RF signals received from the LoRa antenna and conducted through the SMA connector. Received signals move through a single-pole double-throw (SPDT switch), which creates two RF outputs that are filtered according to frequency and conducted to the Semtech SX1257 transceiver modules.

• Semtech SX1257 transceivers

Gateways for LoRaWAN connectivity will carry Semtech LoRa chipsets. These LoRa transceivers are responsible for demodulating and concentrating the received signal.

• SX1301 digital baseband chip

The concentrated signal is then transferred to a digital baseband chip, the SX1301, for further signal processing and transfer to the LoRa gateway core board.

• LoRa gateway core board

This PCB contains a microchip microcontroller and is concerned with receiving data from the radio board and forwarding packet information for Ethernet transfer. The core board is able to wrap the data into a JSON structure for transfer to the network servers through Ethernet cabling. Alternatively, if the gateway model allows, the forwarded data packet can be transferred using a WiFi module or cellular modem on board.

• GPS module

Various models of LoRa gateway also carry a GPS module that can provide positional and chronological data for the unit. This data is acquired via the radio board and processed, packaged, and forwarded via the core board.

• Power module

Low-voltage power can be supplied to a LoRaWAN gateway via onboard micro-USB, USB, AC, DC, or PoE ports. The radio and core boards are usually protected with surface-mount fuses for overcurrent protection.

LoRa gateway components are housed in enclosures suitable for the environment where they will be installed, with outdoor LoRaWAN gateways housed in ruggedized, durable enclosures.

LoRa gateways will either operate using minimal firmware with OTA updates for packet forwarding software (cheaper and more convenient) or, in more expensive models, carry an onboard operating system that allows greater operator control over the gateway.

LoRa gateway frequency bands.

LoRa gateways utilize license-free frequency bands within the radio spectrum. These are:

Due to regulatory restrictions, LoRaWAN antennas are specifically tuned to operate on specific frequency bands that vary depending on the region or country. Here are some of the critical frequency bands for LoRaWAN antennas around the world:

1. EU 868 MHz band: Used in Europe for LoRaWAN, operating between 863-870 MHz.
2. US 915 MHz band: Used primarily in North America, operating between 902-928 MHz.
3. AU 915-928 MHz band: Adopted by Australia and New Zealand.
4. AS 923 MHz band: Adopted by various Asian countries, including Singapore, Thailand, and Hong Kong. The exact frequencies within this range can vary by country.
5. IN 865-867 MHz band: Used in India.
6. KR 920-923 MHz band: Designated for South Korea.
7. RU 864-868 MHz band: Adopted by Russia.

See footnotes for more details about frequency bands for LoRa / LoRaWAN

This means you can install a LoRa gateway without a license, though there may be zoning issues when installing outdoor LoRa antennas.

Antennas for LoRaWAN Gateways: Connectors, Types, Applications

Compatible Wireless Protocols and Technologies

LoRa antennas primarily support the LoRa protocol. However, their inherent characteristics also make them suitable for other wireless technologies. Key among these are:

•  LoRaWAN: The wide-area network protocol specifically designed for LoRa.
• Sigfox: Another low-power, wide-area network technology.
• GSM / 900MHz frequency band
• ISM (Industrial, Scientific, and Medical) Radio Bands: Frequencies often used for low data rate communication in various technologies.

Applications

1. Smart Cities: LoRa antennas help transmit data across vast urban terrains, from traffic management to public utilities.
2. IoT in Agriculture: In precision farming, these antennas help collect data from soil sensors and weather stations spread across large farms.
3. Industrial IoT: Monitoring machinery, equipment health, and factory conditions over expansive industrial zones becomes seamless.
4. IoT in Supply Chain Management and Logistics: Tracking goods in real-time across vast geographies.
5. Remote Area Connectivity: Bridging communication in areas where traditional networks falter.

Key Features

• Long Range: Designed to transmit data over several kilometers, even in dense urban areas.
• Low Power: Ensures the connected devices consume minimal energy, ideal for battery-operated IoT devices.
• Robust Performance: Can function in challenging environments and terrains where weatherproof/waterproofing is critical for components.
• Directional and Omnidirectional Types: Catering to both fixed-point-to-point communication and widespread area coverage, respectively.

Typical Antenna Connectors

LoRa antennas usually come with the following types of connectors:

• SMA
• RP-SMA
• U.FL
• N-type

Torque Ratings of the Antenna Connectors

Correct torque is essential to ensure a reliable connection and minimize signal loss. Typical torque ratings are:

• SMA & RP-SMA: About 3-5 in-lbs for hand tightening.
• N-type: Around 12-15 in-lbs when using a torque wrench.

Types and Typical Materials Composition

1. Whip Antennas: Made from a flexible steel core with a protective rubberized or plastic covering.
2. PCB Antennas: Printed onto a circuit board. They usually consist of copper.
3. Yagi Antennas: Made primarily of metal elements attached to a boom. Common materials include aluminum, copper, and sometimes stainless steel.
4. Dipole Antennas: Typically composed of two metal rods with a central connecting point.

Footnotes: Details about frequency bands of LoRa and LoRaWAN antennas

Not all portions of these bands are always available for LoRaWAN, and there may be specific channels within these bands designated for LoRaWAN usage. Additionally, as regulations evolve and new bands get adopted or adjusted, the specific frequencies for LoRaWAN can change.

Before deploying LoRaWAN devices in a region, ensuring they operate within the legally allocated bands and meet any other regulatory requirements is essential.