function OMEGA = WS_SW(N,K,beta) 

OMEGA = zeros(N,N); 
DNOT = zeros(N,1);
DNOT(1:K/2) = 1; 
DNOT(K/2+2:K+1) = 1;
icon = [K/2+2:K+1];
inot = [K+1:N];
for i =1:N 
% OMEGA(i,:) = circshift(OMEGA(1,:),i-1);    
% inot = find(OMEGA(i,:)>0);  
 NR = sum(rand(K/2,1)<beta);
 i1 = randperm(length(icon),NR); 
 i2 = randperm(length(inot),NR);
 QNOT = DNOT; 
 QNOT(icon(i1)) = 0; 
 QNOT(inot(i2)) = 1;
% dnot = randperm(
% ynot = randperm(N); %create a permutation of size N 
%   OMEGA(i,1:K/2) = QNOT(1:K/2);
%   OMEGA(i,K/2+2:K+2) = QNOT(K/2+1:K); 
OMEGA(i,:) = circshift(QNOT,i-K/2-1);
end
%% 



end