Coding gain

Coding Gain, is the measure in the difference between the SNR levels between the uncoded system & coded system required to reach the same BER levels when used with the ECC.

Example

If the uncoded BPSK system in AWGN environment has a BER of $10^{-}3$ at the SNR level 3dB, and the corresponding Coded (eg BCH) systsem has the same BER at SNR level of 1dB, then we say the coding gain = 3dB-1.5dB = 1.5dB, due to the code (BCH in this case) used.