Forward Error Correction and Code Rate

Forward Error Correction is a process of adding redundant bits to the data to be transmitted. During the transmission, data may get corrupted by interference (changes from 0 to 1 / 1 to 0). These error correction bits are used at the receivers for restoring corrupted bits.

The Code Rate of a forward error correction expresses the proportion of bits in a data stream that actually carry useful information.

There are 4 code rates used in LoRaWAN:

• 4/5
• 4/6
• 5/7
• 4/8

For example, if the code rate is 5/7, for every 5 bits of useful information, the coder generates a total of 7 bits of data, of which 2 bits are redundant.