LoRa modules for industrial IoT and long-range communication

LoRa (Long Range) is a wireless modulation technology based on Chirp Spread Spectrum (CSS). It enables energy-efficient data transmission over long distances at low data rates. LoRa operates on licence-free frequency bands, such as 868 MHz (Europe), 915 MHz (North America), and 433 MHz (Asia), and utilises various Spreading Factors (SF7 – SF12) to adjust range and data rate.

LoRaWAN is a network protocol for IoT applications based on LoRa. Its architecture consists of several components:

• End devices (End Nodes): Sensors or actuators with LoRa chips that send and receive data (transceiver).
• Gateways: Receive LoRa signals and forward them via IP (Ethernet, LTE, Wi-Fi) to the Network Server. A single gateway can cover large areas. Forward packets sent from the server side to the end devices.
• Network Server (NS): Manages communication, filters duplicate messages, and controls network load. -Join Server (JS): Authenticates devices and generates security keys for encryption.
• Application Server (AS): Processes decrypted sensor data and forwards it to the IoT application or cloud platform.

There are two ways to connect an end device to a LoRaWAN network:

Over-the-Air Activation (OTAA):

• Secure method with dynamic key generation.
• The end device sends a Join Request message to the Network Server.
  • The Join Server generates session keys (AppSKey & NwkSKey) for encryption and authentication.
• After successful authentication, the device can send and receive messages.

Activation by Personalisation (ABP):

• Faster method but less secure, as keys are stored permanently in the device.
• No join procedure required; the device can transmit immediately.
• Drawback: Security is weaker because keys are not renewed regularly.

OTAA is recommended, as it generates new, secure keys for each registration.

LoRaWAN employs multiple security mechanisms:

Data encryption:

• AES-128-bit encryption according to the IEEE 802.15.4/2006 standard.

Two separate keys:

• Network Session Key (NwkSKey): Ensures message integrity.
• Application Session Key (AppSKey): Encrypts payload data.

Security during activation:

• OTAA uses dynamic DevNonce values to prevent replay attacks.
• Each new registration generates new keys to counter eavesdropping attempts.

Protection against attacks:

• Message Integrity Code (MIC): Ensures messages are not tampered with.
• Frame Counter Mechanism: Prevents replay attacks.
• End-to-end encryption: Ensures that even the Network Server cannot access payload data.

These mechanisms make LoRaWAN reliable and secure for IoT applications.

The range depends on frequency, transmission power, receiver sensitivity, environmental conditions, antenna characteristics, and other factors. Walls, buildings, and interference can significantly reduce the range. The theoretical range can be calculated using the link budget and the "free space path loss formula."

LoRaWAN is suitable for large-scale, wireless IoT networks.

The range also depends on the Spreading Factor (SF) used. The following ranges are typically specified:

• Rural areas: Up to 15 km with SF12.
• Urban areas: 2–5 km, depending on building density.
• Industrial environments: 1–3 km, as metal structures attenuate signals.

Practical ranges should be verified with specific RF modules and applications.

LoRaWAN is suitable for numerous IoT applications, including:

• Smart Cities: Intelligent street lighting, parking management, air quality sensors.
• Agriculture: Soil moisture sensors, livestock tracking, weather stations.
• Industry 4.0: Asset tracking, process monitoring, machine maintenance.
• Environmental monitoring: Flood detection, wildfire early warning systems.

LoRaWAN is ideal for energy-efficient, large-scale IoT networks

LoRaWAN is optimised for low data rates, with transmission speeds between 0.3 kbit/s and 50 kbit/s:

• Higher range (SF12) → Slower transmission (~300 bit/s).
• Lower range (SF7) → Faster transmission (~11 kbit/s).

Since LoRaWAN is designed for sensor-based, periodic data transmissions, these data rates are sufficient for many IoT applications.

When planning an application, factors such as duty cycle ("on-air time") and packet loss (potential retransmissions) should be considered.

The Adaptive Data Rate (ADR) in LoRa is a mechanism designed to optimize the transmission rate and transmission power based on current network conditions and the distance between devices and gateways.

Here are the key points:

• Data Rate: ADR optimizes the data rate to maximize communication efficiency. Higher data rates facilitate faster transmissions, while lower data rates provide more stable connections.
• Transmission Power: By adjusting transmission power, ADR improves energy efficiency. Devices close to the gateway can transmit at lower power, while more distant devices may need higher power to maintain connectivity.
• Automatic Adjustment: ADR allows for automatic parameter adjustments based on the reception of acknowledgments and network conditions, helping find the right balance between range and energy consumption.
• Goal: The main purpose of ADR is to extend the battery life of IoT devices while ensuring reliable communication.

LoRaWAN operates on various licence-free ISM bands, which vary by region:

• Europe: 868 MHz (EU868).
• North America: 915 MHz (US915).
• Asia: 433 MHz (AS433) & 920-925 MHz (AS920).
• Australia: 915-928 MHz (AU915).

These frequency bands enable cost-free operation, though subject to transmission time limitations (duty cycle restrictions).

A full list of specified frequency bands can be found in the "LoRaWAN® Regional Parameters RP002-1.0.4" by the LoRa Alliance.

Note: Semtech, the primary developer of LoRa technology, has introduced LoRa chips supporting 2.4 GHz, such as the SX1280 and SX1281 transceivers. These use a proprietary, non-standardised version of LoRa.

LoRaWAN devices have low power consumption and enable a battery life of typically up to 10 years (the real battery life must be calculated according to the requirements of the specific application).

Device classes:

• Class A (standard mode): Highly energy-efficient, only short transmission times (with the following reception windows).
• Class B (scheduled receive windows): Allows synchronised communication but with higher consumption.
• Class C (continuous reception mode): High energy consumption but lower latency.

For battery-powered sensors, Class A is the best choice.

A single LoRaWAN gateway can manage thousands of devices simultaneously, depending on: • Data rate and Spreading Factor: Higher SF values reduce gateway capacity. • Packet size and transmission interval: Shorter messages and longer intervals increase device capacity. • Environmental conditions: Interference from other radio systems can decrease capacity.

A well-planned LoRaWAN network can efficiently support a large number of sensors.

The “LoRa Alliance” is an international organization focused on promoting and developing the LoRaWAN technology. LoRaWAN (Long Range Wide Area Network) is a protocol designed for wireless networks, specifically for the communication of IoT devices (Internet of Things) over long distances and with low energy consumption.

Main Objectives of the LoRa Alliance:

• Standardization: Promote global acceptance and standardization of the LoRaWAN technology.
• Interoperability: Ensure devices from different manufacturers can communicate with each other.
• Market Development: Support the development of markets and applications based on LoRaWAN technology.
• Training and Resources: Provide training materials, documentation, and resources for developers and companies looking to leverage LoRaWAN technology.

Membership The LoRa Alliance comprises various members, including companies from telecommunications, software, hardware, and more. Membership offers companies the opportunity to actively participate in the ongoing development of the technology and benefit from shared resources.