Introduction to LoRa Technology

LoRa, which stands for Long Range, is a proprietary spread spectrum modulation technique derived from chirp spread spectrum (CSS) technology. Developed by Semtech, LoRa is a long range, low power wireless platform that has become the de facto technology for Internet of Things (IoT) networks worldwide.

LoRa technology enables smart IoT applications that solve some of the biggest challenges facing our planet: energy management, natural resource reduction, pollution control, infrastructure efficiency, disaster prevention, and more. LoRa devices and the open LoRaWAN® protocol enable the seamless interoperability of smart things without the need for complex local installations and give back the freedom to users, developers, and businesses enabling the roll out of Internet of Things.

Key Features of LoRa Technology

1. Long Range: A single base station using LoRa Technology can cover entire cities or hundreds of square kilometers.
2. Low Power: The LoRa Technology power consumption is very low, allowing the sensors to last for years on a single charge.
3. Secure: LoRa Technology secures all communications using end-to-end AES128 encryption.
4. Standardized: LoRaWAN, a Low Power, Wide Area (LPWA) networking protocol based on LoRa Technology, has been standardized by the LoRa Alliance, an open association of members who believe that the Internet of Things era is now.
5. Low Cost: LoRa Technology reduces up-front infrastructure investments and operating costs, as well as end-node sensor costs.

LoRa Alliance

The LoRa Alliance® is an open, nonprofit association that has become one of the largest and fastest-growing alliances in the technology sector since its inception in 2015. Its members closely collaborate and share expertise to develop and promote the LoRaWAN® protocol as the leading open global standard for secure, carrier-grade IoT LPWAN connectivity. With the technical flexibility to address a broad range of IoT applications, both static and mobile, and a certification program to guarantee interoperability, LoRaWAN® has already been deployed by major mobile network operators globally, with continuing wide expansion into 2020 and beyond.

LoRa Technology Overview

LoRa is a long range, low power wireless platform that is quickly becoming the de facto IoT network worldwide. LoRa fills the technology gap between cellular and Wi-Fi/BLE, covering a wide range of IoT applications from smart cities to industrial IoT to agriculture and more.

LoRa Physical Layer

At the physical layer (the lowest layer of the OSI model), the LoRa modulation format is based on chirp spread spectrum (CSS) with integrated Forward Error Correction (FEC). CSS was developed in the late 1940s and uses wideband linear frequency modulated chirp pulses to encode information. In CSS, the data signal is modulated using chirp pulses, where the frequency increases or decreases over a certain amount of time. The resulting signal has similar characteristics to a frequency modulation (FM) signal, but is much more robust to channel noise. The CSS modulated data is then encoded with FEC code to further increase the robustness against interference. The combination of CSS modulation and FEC coding allows LoRa to increase the communication distance and immunity to interference at the expense of data rate.

LoRaWAN Protocol

LoRaWAN is an open protocol developed by the LoRa Alliance to support large scale public or multi-tenant networks. The LoRaWAN specification provides seamless interoperability among smart things without the need of complex local installations, and empowers the user, developer, or business, by enabling the roll out of Internet of Things.

Key features of the LoRaWAN protocol include:

1. Secure bi-directional communication, mobility and localization services
2. Low power consumption for multi-year battery lifetime
3. Connectivity to sensors and actuators using LoRa or FSK modulation
4. Seamless interoperability among smart things without the need of complex local installations
5. Geolocation using RSSI and TDOA
6. Open standard with a certification program to guarantee interoperability

LoRa Network Architecture

A typical LoRa network architecture is a “star-of-stars” topology, where each end-point communicates with a gateway, and each gateway relays the messages between the end-devices and a central network server. The network server manages the overall network, including the security keys, application logic, and data forwarding to application servers.

End-devices

End-devices are the ‘things’ in the IoT that have LoRa connectivity, and can communicate with gateways using LoRa or FSK modulation. End-devices can be classified into three categories based on how often they need to send data and how much downlink communication they require from the network.

Class	Description	Downlink	Battery Life
Class A	Default class, must be supported by all end-devices. Uplink transmissions are scheduled by the end-device based on its own communication needs. Each uplink transmission is followed by two short downlink windows.	Downlink communication from the server at previously scheduled times. Suitable for applications that only require downlink communication from the server shortly after the end-device has sent an uplink transmission.	Longest battery life.
Class B	End-devices open extra receive windows at scheduled times in addition to Class A receive windows.	Downlink communication at scheduled times in addition to Class A downlink. Suitable for applications with additional downlink traffic needs.	Shorter battery life compared to Class A due to the additional downlink windows.
Class C	End-devices have nearly continuously open receive windows, only closed during transmission.	Downlinks can be sent by the server at any time as long as the end-device is not transmitting. Suitable for applications with maximal downlink needs.	Shortest battery life.

Gateways

Gateways are the access points of the LoRa network, receiving messages from end-points and forwarding them to the network server. Gateways are usually connected to the network server over Ethernet, Cellular, or Wi-Fi backhauls.

Some key points about LoRa Gateways:

• Gateways can receive messages from multiple end-points simultaneously on different channels and using different spreading factors.
• Gateways are not associated with a particular end-point, all gateways within range of an end-point will receive the messages.
• Gateways do not have any prior knowledge about which end-points are in their vicinity, simplifying the deployment.

Network Server

The network server is the central intelligence of the LoRa network responsible for the following functions:

• Aggregate and de-duplicate the data received from the gateways.
• Perform security checks and decrypt the application payload if needed.
• Route the data to the correct application server.
• Schedule and prioritize the downlink data to the end-points.
• Manage and update the firmware on the end-points.

The network server also exposes APIs and interfaces to manage the network infrastructure and handle network events.

LoRa Performance

The LoRa modulation is very robust and can demodulate signals that are up to 19.5 dB below the noise floor, enabling very long communication distances. The maximum communication distance depends on the environment and the obstructions in the path between the end-point and gateway, but LoRa can achieve up to 15 km range in suburban areas and up to 5 km range in urban areas.

Link Budget

The link budget is the accounting of all the gains and losses in the communication link between the transmitter and the receiver. It is expressed in decibels (dB) as the maximum allowable path loss (PL) that the communication link can handle.

The LoRa link budget can be calculated as follows:

Link Budget (dB) = Transmit Power (dBm) - Receiver Sensitivity (dBm)

where:
– Transmit Power is the power output of the transmitter
– Receiver Sensitivity is the lowest power level at which the receiver can detect an input signal and demodulate data

The following table shows the achievable link budget for different LoRa spreading factors and bandwidths:

Bandwidth (kHz)	Spreading Factor	Coding Rate	Sensitivity (dBm)	Link Budget (dB)
125	7	4/5	-123	155
125	8	4/5	-126	158
125	9	4/5	-129	161
125	10	4/5	-132	164
125	11	4/5	-134.5	166.5
125	12	4/5	-137	169

As we can see from the table, LoRa can achieve very high link budgets, up to 169 dB with SF12 and 125 kHz bandwidth. This translates to very long communication distances, even in challenging environments with a lot of obstructions.

Data Rate

The data rate of LoRa varies depending on the spreading factor (SF) and bandwidth (BW) used. Higher spreading factors and lower bandwidths result in lower data rates but longer communication distances, while lower spreading factors and higher bandwidths result in higher data rates but shorter communication distances.

The following table shows the achievable data rates for different LoRa configurations:

Bandwidth (kHz)	Spreading Factor	Coding Rate	Data Rate (bps)
125	7	4/5	5470
125	8	4/5	3125
125	9	4/5	1760
125	10	4/5	980
125	11	4/5	440
125	12	4/5	250
250	7	4/5	11000
250	8	4/5	6250
250	9	4/5	3500
250	10	4/5	1950
250	11	4/5	980
250	12	4/5	490

As we can see, the data rates range from 250 bps up to 11 kbps depending on the LoRa configuration used. While these data rates may seem low compared to other wireless technologies like Wi-Fi or cellular, they are sufficient for many IoT applications that only need to send small amounts of data infrequently.

LoRa Use Cases and Applications

LoRa technology enables a wide range of IoT applications in various industries and verticals. Some of the most common use cases for LoRa include:

Smart Cities

• Smart parking: monitoring of parking spaces availability in the city.
• Structural health: monitoring of vibrations and material conditions in buildings, bridges and historical monuments.
• Waste management: detection of rubbish levels in containers to optimize the trash collection routes.
• Smart lighting: intelligent and weather adaptive lighting in street lights.

Smart Environment

• Forest fire detection: monitoring of combustion gases and preemptive fire conditions to define alert zones.
• Air pollution: control of CO2 emissions of factories, pollution emitted by cars and toxic gases generated in farms.
• Landslide and avalanche prevention: monitoring of soil moisture, vibrations and earth density to detect dangerous patterns.
• Earthquake early detection: distributed control in specific places of tremors.

Smart Agriculture

• Irrigation: real-time monitoring of soil moisture and activation of irrigation systems when needed.
• Livestock monitoring: location and identification of animals grazing in open pastures or location in big stables.
• Weather station network: study of weather conditions in fields to forecast ice formation, rain, drought, snow or wind changes.

Smart Industry

• Machine control: real-time monitoring and performance optimization of industrial machinery and processes.
• Asset tracking: location and identification of goods and stocks in warehouses for inventory purposes.
• Safety and security: detection of liquid and gas leakages in industrial environments and monitoring of workforce safety.

FAQ

What is the range of LoRa?

The range of LoRa depends on the environment and obstructions, but it can achieve up to 15 km range in suburban areas and up to 5 km range in urban areas.

What is the data rate of LoRa?

The data rate of LoRa varies from 250 bps to 11 kbps depending on the spreading factor and bandwidth used.

What is the battery life of LoRa devices?

LoRa devices can last for years on a single battery charge due to the low power consumption of the LoRa modulation.

Is LoRa secure?

Yes, LoRa uses end-to-end AES128 encryption to secure all communications.

What are the main applications of LoRa?

The main applications of LoRa include smart cities, smart environment, smart agriculture, and smart industry. LoRa enables a wide range of IoT use cases such as smart parking, waste management, irrigation, asset tracking, and more.

Conclusion

LoRa is a powerful long range, low power wireless platform that is quickly becoming the de facto technology for IoT networks worldwide. With its ability to cover entire cities or hundreds of square kilometers with a single base station, while consuming very little power, LoRa is enabling a wide range of IoT applications that were previously not possible or economically feasible.

The LoRaWAN protocol, developed by the LoRa Alliance, provides a standardized way for IoT devices to communicate with each other and with the cloud, ensuring interoperability and security. The LoRa Alliance has grown to over 500 members since its inception in 2015, a testament to the growing adoption and importance of LoRa technology.

As the IoT continues to grow and evolve, with billions of devices expected to be connected in the coming years, LoRa will play a crucial role in enabling this growth and making the IoT a reality. From smart cities to industrial IoT, agriculture to logistics and supply chain, LoRa is already being used in a wide range of applications and use cases, with many more to come in the future.