Microsoft's smartphone platform might be a distant third compared to Google's Android and Apple's iOS, but Microsoft has been earning a significant amount of money from Android device manufacturers through its patents, and has even sued some of these companies.
(Also see: Microsoft reportedly pocketing a cool $2 billion per year in Android royalties)
The details of these patents have not been clear, but according to an Ars Technica report the Chinese government has now published a list of 310 patents and patent applications that Microsoft holds, which appear to be the key patents which Android is seen to be in violation of.
It's for this reason that Microsoft has patent deals with Android OEMs like LG, Samsung, HTC, and Acer for their Android and Chrome OS based products. Recently, Microsoft also signed a patent licensing agreement with Dell for Android and Chrome OS.
Right now, Motorola remains one of the few large companies that is still a holdout in these patent agreements.
The list of patents that Microsoft holds was produced as part of a Chinese government anti-trust review of Microsoft's purchase of Nokia, and is discussed in the official Microsoft Blog by David Howard, Corporate VicePresident and Deputy General Counsel, Litigation and Antitrust, Microsoft. He writes that the Chinese Ministry of Commerce (MOFCOM) concluded after its investigation that Microsoft holds approximately 200 patent families that are necessary to build an Android smartphone.
There is a Chinese language list of the patents that gives more details on the technology. Of course, the publishing of this list will not have any impact on Microsoft's patents and agreements, butit is still interesting to see how and why it has been able to earn up to $6 to $8 for every Android device being sold to us.