AF Cooperative Diversity MATLAB Code (Variable gain vs Fixed gain)

Hi

if I have dual hop cooperative system; S (source), R(Relay), and D (Destination).
and we have H_sr , H_rd for the fading channels between source-relay and relay-destination respectively.

Ps is the Source Power;
Pr is the relay Power;
N is the total number of bits;
G is the AMPLIFICATION FACTOR by the RELAY;
No is the noise power

H_sr = sqrt(0.5)*(randn(1,N)+1i.*randn(1,N))
H_rd = sqrt(0.5)*(randn(1,N)+1i.*randn(1,N))



G^2=Pr./(Ps.*H_sr_gain^2 + No(i)); for variable gain cooperative

G^2=Pr./(Ps.*/H_sr_gain/^2 + No(i)); for fixed gain cooperative


My questions are:

1- Are the above Gain equations correct ?

2- how to calculate the values of H_sr_gain^2 and /H_sr_gain/^2 (I mean by Matlab)?

3- what are the approximate values of the H_sr_gain^2 and /H_sr_gain/^2 ?



Thanks