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I have been given an equation to calculate the symbol error probability as:

Pes = [itex]\frac{N}{2}[/itex]erfc([itex]\sqrt{\frac{m.d^{2}_{0}}{4γ} . \frac{Eb}{N0}}[/itex])

Whereby:

N = Average number of nearest neighbours (symbols)

m = no of bits per symbol

d0 = euclidean distance to nearest neighbours

Eb = energy per bit

N0 = noise

(Eb/No = SNR)

I cannot however find the meaning of γ (gamma)

I have found several definitions of it for various constellation types:

M-ASK - γ = (M^{2}-1) / 3

M-PSK - γ = 1

M-QAM - γ = 2(M-1) / 3

Does anyone know the meaning of gamma and how, given a constellation diagram, it may be calculated?

This isn't homework btw, it exam revision :-s

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# Symbol Error Probability for AWGN channels

Can you offer guidance or do you also need help?

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