title: Do WiFi devices transmit packets when they are just turned on?
body: <p>I read a lot about WiFi sensors being used to track smart phones in Retail environment. The location triangulation is done on basis that a smart phone has its WiFi turned ON, be it in connected or unconnected state. </p>
  
  <h2>Case 1 : WiFi turned ON but unconnected</h2>
  
  <p>Why should a smart phone which has its WiFi turned ON need to transmit the packets, unless the user 'scans' for nearby WiFi networks? </p>
  
  <h2>Case 2 : WiFi turned ON and connected</h2>
  
  <p>Why should a smart phone transmit any packets, unless the user is browsing the net?</p>
  
  <p><br></p>
  
  <p>In both the above cases, there is a high chance that most of the time the WiFi device does not send any packet, which means none of the WiFi sensors detect it. If that is true, then the whole idea behind WiFi sensor based triangulation in Retail goes for toss, clearly with so many companies working on this, I must be wrong. Please answer with more than a yes or no, as to which packets are generally sent in both the above scenarios.</p>