diff --git a/demapper b/demapper
new file mode 100644
index 0000000..5c0b910
--- /dev/null
+++ b/demapper
@@ -0,0 +1,33 @@
+function [map_out]=demapper(data,mode,c)
+
+m_out=data;
+% mode : Modulation order in power of 2 (1/2/4/6 = BSPK/QPSK/16-QAM/64-QAM)
+% c = 1;
+
+switch mode
+    case 1
+        b=c*[1 -1];
+    case 2
+        b=c*[1+1i -1+1i 1-1i -1-1i];
+    case 4
+        b=c*[1+1i 1+3i 1-1i 1-3i 3+1i 3+3i 3-1i 3-3i -1+1i -1+3i -1-1i -1-3i -3+1i -3+3i -3-1i -3-3i];
+    case 6
+        b=c*[3+3i 3+1i 3+5i 3+7i 3-3i 3-1i 3-5i 3-7i 1+3i 1+1i 1+5i 1+7i 1-3i 1-1i 1-5i 1-7i 5+3i 5+1i 5+5i 5+7i 5-3i 5-1i 5-5i 5-7i 7+3i 7+1i 7+5i 7+7i 7-3i 7-1i 7-5i 7-7i -3+3i -3+1i -3+5i -3+7i -3-3i -3-1i -3-5i -3-7i -1+3i -1+1i -1+5i -1+7i -1-3i -1-1i -1-5i -1-7i -5+3i -5+1i -5+5i -5+7i -5-3i -5-1i -5-5i -5-7i -7+3i -7+1i -7+5i -7+7i -7-3i -7-1i -7-5i -7-7i];
+    otherwise
+        error('wrong choice');
+end
+
+temp = zeros(size(m_out));
+
+for k=1:length(m_out)
+    z=find( (abs(b-m_out(k))).^2-min(abs((b-m_out(k))).^2)==0);
+    if length(z)==1
+        temp(k)=z-1;
+    else
+        temp(k)=z(randi(1,1,[1,length(z)]))-1;
+    end
+end
+
+dmod_out = de2bi(temp,mode);
+map_out = reshape(dmod_out',1,mode*length(temp));
+