Is Microsoft charging for its patent from each Android device sold? I read here that Microsoft is cashing Android handset ODMs for some patents that are allegedly used in their Android handsets. Why is Microsoft able to do that? Is this a HW or SW-based problem?
The list includes 73 standard-essential patents, but there’s also 127
  patents that Microsoft claims are implemented in Android. Some on the
  list, as Ars Technica notes, include patents that Microsoft acquired
  as part of the Rockstar Consortium to bid on patents from Nortel.
  ...
  Microsoft is estimated to earn as much as $1 billion a year from 
  Android-related licensing revenue.


ref : http://www.theverge.com/2014/6/16/5813710/microsoft-android-patents-list