Transmitted bits at the receiver are detected using SOFT Detection Technique, i.e. if the received bit is positive it is detected as +1 and if the bit is negative it is detected as -1. AWGN with mean 0 and variance 1 is used at the receiver. If the transmitted bit is -1, it is received as -(sqrt(P))+n, where n is Gaussian Noise and P is signal power. As noise is having 0 mean, -sqrt(SNR) is used instead of -sqrt(P). Similarly if the transmitted bit is +1 then it is received as +(sqrt(SNR))+n.
Submitted as a toolbox
Some clarification on the detection scheme used has been given.
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