How to calculate SNR for simulation in Matlab ?

I have the following Matlab code:

x=transpose(round(rand(1,n_bits)));

% Transmitter 1

k1=log2(M1);

EbNo1=10^(EbNodB1/10);

h1a=modem.qammod(M1);

h1a.inputtype='bit';

h1a.symbolorder='gray';

y1=modulate(h1a,x);

% Channel 1

Eb1=mean((abs(y1)).^2)/k1;

sigma1=sqrt(Eb1/(2*EbNo1));

w1=sigma1*(randn(n_bits/k1,1)+1i*randn(n_bits/k1,1)); % Noise

hf1=(1/sqrt(2))*(randn(n_bits/k1,1)+1i*randn(n_bits/k1,1)); %fading

r1=hf1.*y1;

r1a=r1+w1;

Can you tell me how to calculate the SNR after the signal go through the channel?? Thanks so much :)