LoRaWAN Spreading Factor, Range, and Data Rate Explained

This page explains the LoRaWAN spreading factor, range, and data rate used in LoRa systems. We’ll explore the relationship between these terms, including tables and formulas. These concepts are tied to the chirp spread spectrum (CSS) modulation technique.

CSS utilizes wideband linear frequency modulated chirp pulses to encode baseband information. It’s favored in space and military communications due to its long range, low transmit power, and resilience to interference.

LoRaWAN Spreading Factor

LoRa modulation in LoRaWAN uses chirp spread spectrum for encoding. Each bit is spread using a “chipping factor.” The number of chips per bit is the spreading factor. In essence, the duration of the chirp represents the spreading factor. CSS typically employs spreading factors from 7 to 12. The spreading factors vary by region, as shown in the following tables.

Lower spreading factors offer higher bit rates (or LoRaWAN data rates) and require less “Over The Air” (OTA) time. Conversely, higher spreading factors result in lower data rates but require more airtime.

LoRaWAN spreading factor and data rate in Australia

LoRaWAN spreading factor and data rate in Europe

LoRaWAN spreading factor and data rate in USA

LoRaWAN spreading factor and data rate in INDIA

In these tables, “RFU” stands for “Reserved for Future Usage.”

LoRaWAN Range (Distance)

The range signifies the distance a LoRaWAN signal can cover to serve multiple end devices from a single tower. The LoRaWAN range can be derived from the free space path loss equation:

LoRa range vs free space path loss

One experiment demonstrated a LoRaWAN range of 702.676 km using only 25 mW (14dBm) of transmit power across the German border. The LoRaWAN gateway was positioned at a height of 30 meters.

LoRaWAN Data Rate

Data rate is the speed at which data is transmitted from one point to another via a wired or wireless medium.

Data Rate = Number of bits transferred / Total time taken for transfer

Different wireless technologies have varying data rate ranges based on their physical layer parameters (modulation, code rate, etc.) and radio parameters (bandwidth, number of carriers, etc.). LoRaWAN is also a wireless system. The LoRaWAN data rate depends on the spreading factor, bandwidth, and code rate, as described in the equation below.

LoRaWAN Data Rate vs. Spreading Factor Conversion Calculator

The following equation shows the relationship between LoRa data rate, LoRa spreading factor, code rate, and bandwidth.

LoRa Data Rate Formula