Go back N Protocol [Matlab code]

clc;

clear all;

n=input('Number Of Frames: ');

w=input('Window Size: ');

pt=1;

flag=0;

flag2=0;

a=1:n;

while flag==0

if flag2==0

%Transmitting The Frames In A Window

for i=1:w

fprintf('Frame %d Transmitted\n',a(pt));

pt=pt+1;

end

flag2=1;

end

s=randint(1,1,10);

if s>3

fprintf('PAK of Frame %d Received\n',a(pt-w));

fprintf('Frame %d Transmitted\n',a(pt));

if a(pt)==n

flag=1;

end

pt=pt+1;

else

fprintf('NAK Of Frame %d Received\n',a(pt-w));

for j=0:w-1

fprintf('Frame %d Discarded\n',a(pt-w+j));

end

pt=pt-w;

flag2=0;

end

end

%Last 'W' Frames are dealt seperately

i=n-w+1;

while (i<=n)

s=randint(1,1,10);

if s>4

fprintf('PAK of Frame %d Received\n',a(i));

i=i+1;

else

fprintf('NAK of Frame %d Received \n',a(i));

for j=i:n

fprintf('Frame %d Discarded\n',a(j));

end

for k=i:n

fprintf('Frame %d Transmitted\n',a(k));

end

end

end