With the rapid development of Internet of Things (IoT) technology, indoor positioning has become a highly concerned application field. LoRa technology is widely used in the field of Internet of Things (IoT) due to its low power consumption, long distance and low cost. Although LoRa is mainly used for long-distance communication, its application in indoor positioning has gradually attracted attention.

Technical Principles

The main technical principles of LoRa for indoor positioning include: received signal strength indication (RSSI), time difference of arrival (TDoA) and time of arrival (ToA).

  1. Signal Strength Indication (RSSI)

lBasic principle: By measuring the received signal strength indication (RSSI) of the LoRa signal, the distance between the device and the base station is estimated. The larger the RSSI value, the closer the device is to the base station.

lPositioning method: Use multiple base stations to measure the RSSI value of the same device, and calculate the location of the device by triangulation or multilateral measurement.

  1. Time Difference of Arrival (TDoA)

lBasic principle: By measuring the time difference (TDoA) of the signal arriving at different base stations, the distance difference between the device and the base station is calculated.

lPositioning method: Use multiple base stations to measure the TDoA value of the same device, and determine the location of the device through geometric calculation.

  1. Time of Arrival (ToA)

lBasic principle: By measuring the arrival time (ToA) of the signal from the device to the base station, the distance between the device and the base station is directly calculated.

lPositioning method: Use multiple base stations to measure the ToA value of the same device, and calculate the location of the device through triangulation.

Comparison of advantages and disadvantages:

Advantages:

Low power consumption: The low power consumption characteristics of LoRa technology make it suitable for battery-powered devices, extending the service life of the device.

lLong distance: LoRa's long-distance communication capability makes it possible to perform indoor positioning over a large range, reducing the number of base stations deployed.

lLow cost: The cost of LoRa modules and base stations is low, suitable for large-scale deployment.

Strong penetration: LoRa signals have strong penetration and can penetrate walls and other obstacles, improving the coverage of indoor positioning.

Disadvantages:

Low positioning accuracy: Due to the low bandwidth and long distance characteristics of LoRa, the positioning accuracy is relatively low, usually between a few meters and tens of meters.

l Poor real-time performance: The low data rate and long transmission time of LoRa result in poor real-time performance of positioning data, which is not suitable for applications that require high real-time performance.

Multipath effect: The multipath effect in indoor environments affects the propagation of signals, resulting in increased positioning errors.

Solution application

Positioning solution based on RSSI

  1. LoRa terminal devices send signals regularly
  2. Multiple LoRa base stations receive the signal and measure the RSSI value.
  3. The base station sends the RSSI value to the positioning server
  4. The location server calculates the device's location through triangulation or multilateration

TDoA-based positioning solution

  1. LoRa terminal devices send signals periodically.
  2. Multiple LoRa base stations receive signals and measure arrival time
  3. The base station sends the arrival time to the positioning server.
  4. The positioning server determines the location of the device through geometric calculations.

Summary

LoRa technology has the advantages of low power consumption, long distance and low cost in indoor positioning, and is suitable for application scenarios that require large-scale coverage and long-term operation. However, due to its low positioning accuracy and real-time performance, LoRa is more suitable for applications that do not require high positioning accuracy, such as asset tracking, environmental monitoring and simple personnel positioning. By combining positioning methods such as RSSI, TDoA and ToA, LoRa can achieve basic positioning functions in indoor environments. Compared with other positioning technologies, LoRa has obvious advantages in power consumption and coverage, but has certain shortcomings in positioning accuracy and real-time performance. Therefore, choosing a suitable positioning technology requires a trade-off based on the needs of specific application scenarios.