The , particularly when it comes to "non-practicing entities," outfits that exist only to acquire patents and sue real tech companies. One such entity against Google over its use of . 

But Microsoft, Oracle and Apple are not mere patent trolls, and have the financial resources - and perhaps enough intellectual property - to hamstring Android's rise.

"Android is on fire. More than 550,000 Android devices are activated every day, through a network of 39 manufacturers and 231 carriers," Drummond writes in the Google blog.

"A smartphone might involve as many as 250,000 (largely questionable) patent claims, and our competitors want to impose a 'tax' for these dubious patents that makes Android devices more expensive for consumers. They want to make it harder for manufacturers to sell Android devices. Instead of competing by building new features or devices, they are fighting through litigation."

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