--- a/src/wifi/model/block-ack-cache.cc	Wed Jan 28 06:34:11 2015 -0800
+++ b/src/wifi/model/block-ack-cache.cc	Wed Jan 28 10:11:32 2015 -0800
@@ -39,6 +39,12 @@
   memset (m_bitmap, 0, sizeof (m_bitmap));
 }
 
+uint16_t
+BlockAckCache::GetWinStart ()
+{
+  return m_winStart;
+}
+
 void
 BlockAckCache::UpdateWithMpdu (const WifiMacHeader *hdr)
 {