Ⅰ. Theoretical transmission range of LoRa

1.Maximum distance in ideal environment

Open space (no obstacles):
When the transmission power is 14 dBm (25 mW), the theoretical maximum distance can reach 15–20 km.

When the transmission power is 27 dBm (500 mW), the theoretical maximum distance can reach 50–100 km (high-gain antenna required).

Extreme case: In ideal environments such as deserts or plains, the transmission distance of LoRa modules can even reach more than 200 kilometers (such as satellite communication scenarios).

2. Typical distance in actual environment

Urban environment:
Dense urban area (obstructed by high-rise buildings): 1–5 kilometers.

Suburban or rural areas: 5–15 kilometers.

Industrial environment:
Complex environments such as factories and warehouses: 1–10 kilometers (depending on the density of obstacles).

Ⅱ.key factors affecting the transmission range of LoRa

1. Transmit power (Tx Power)

Regulatory restrictions: Different countries have strict regulations on LoRa transmit power:

China: Transmit power ≤ 14 dBm (433 MHz band).

Europe: Transmit power ≤ 14 dBm (868 MHz band).

United States: Transmit power ≤ 30 dBm (915 MHz band).

Actual impact: The higher the transmit power, the longer the transmission distance, but power consumption and regulatory compliance need to be weighed.

2. Receive sensitivity (Rx Sensitivity)

The receive sensitivity of LoRa is related to its spreading factor (SF) and bandwidth (BW):

Spreading factor (SF): SF7 (highest sensitivity) to SF12 (lowest sensitivity).

SF7: Receive sensitivity 75 dBm (short transmission distance, high rate).
SF12: Receive sensitivity 137dBm (long transmission distance, low rate).
Bandwidth (BW): The narrower the bandwidth, the higher the receive sensitivity (e.g. 125 kHz is more sensitive than 500 kHz).

3. Frequency selection

433 MHz / 868 MHz / 915 MHz:

Low frequency (433/868 MHz): Strong penetration, good diffraction ability, suitable for complex environments.

High frequency (915 MHz): Higher transmission rate, but weaker diffraction ability (suitable for open areas).

4. Antenna gain and directivity

High-gain antenna (such as 5 dBi or above): can significantly increase the transmission distance (+3 dB gain ≈ double the transmission distance).

Omnidirectional antenna: suitable for wide-area coverage, directional antenna (such as Yagi) can extend the point-to-point distance.

5. Environmental interference

Obstacles: Buildings, trees, and metal structures will significantly attenuate the signal.
Weather: Rain, snow, and haze have little effect on LoRa signals (due to their longer wavelengths).

III. Actual measurement of the transmission range of a typical LoRa module

1. SX1276/SX1278 module

Parameters:
Transmit power: 27 dBm (500 mW).
Receive sensitivity (SF12): -137 dBm.

Actual measurement distance:
Open space: 50–100 km (high-gain antenna required).
Suburban area: 10–30 km.

2. LoRaWAN gateway and terminal device

Terminal device (SF12, 14 dBm):
Urban environment: 3–8 km.
Suburban area: 10–20 km.

Gateway (omnidirectional antenna, 27 dBm):
Coverage radius can reach 5–15 km (dense urban area).

IV. Tips for optimizing LoRa transmission range

1. Parameter configuration optimization

Reduce data rate: select a higher spreading factor (SF12) and a narrower bandwidth (125 kHz).
Shorten message length: reduce transmission time and packet loss rate.

2. Hardware optimization

Use high-gain antennas: such as flat antennas or parabolic antennas.
Optimize antenna position: avoid metal obstruction and increase antenna height.

3. Protocol optimization

Enable ADR (Adaptive Data Rate): dynamically adjust SF and bandwidth according to channel quality.
Reduce retransmission times: reduce repeated transmissions by optimizing link quality.

V. Comparison of LoRa with other wireless technologies

VI. Notes

Regulatory compliance: Different countries have strict restrictions on LoRa frequency bands and power, and local policies (such as FCC, CE certification) must be followed.

Network deployment: In wide-area applications, multiple gateways need to be deployed to cover a larger area.

Anti-interference design: Avoid sharing frequency bands with 2.4 GHz devices such as Wi-Fi and Bluetooth.

Summary

Theoretical range: LoRa modules can reach 50–100 km in open space (high power + high gain antenna).

Actual range: Typically 3–20 km in urban environments, depending on environmental complexity.

Optimization direction: Reasonably configure SF/BW, use high-gain antennas, and reduce data rates.