Coding gain

In coding theory and related engineering problems, coding gain is the measure in the difference between the signal to noise ratio (SNR) levels between the uncoded system and coded system required to reach the same bit error rate (BER) levels when used with the error correcting code (ECC).

Example

If the uncoded BPSK system in AWGN environment has a Bit error rate (BER) of $10^{-3}$ at the SNR level 3dB, and the corresponding coded (e.g., BCH) system has the same BER at an SNR level of 1.5dB, then we say the coding gain = 3dB-1.5dB = 1.5dB, due to the code (BCH in this case) used.