**Quantized QAM Performance**

The following definitions are needed in determining error rates:

- = Number of symbols in modulation constellation
- = Energy-per-bit
- = Energy-per-symbol = with
*k*bits per symbol - = Noise power spectral density (W/Hz)
- = Probability of bit-error
- = Probability of bit-error per carrier
- = Probability of symbol-error
- = Probability of symbol-error per carrier

is related to the complementary Gaussian error function by:, which is the probability that *x* will be under the tail of the Gaussian PDF towards positive infinity.

The error rates quoted here are those in additive white Gaussian noise (AWGN).

Where coordinates for constellation points are given in this article, note that they represent a *non-normalised* constellation. That is, if a particular mean average energy were required (e.g. unit average energy), the constellation would need to be linearly scaled.

Read more about this topic: Quadrature Amplitude Modulation

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