An analysis of more than 1,000 patents that Google bought from IBM offers a glimpse inside the search giant's increasingly frantic efforts to protect its Android mobile operating system against legal attacks from competitors.

IPVision, which makes patent-analyzing software, says that the 1,029 patents that Google bought from IBM in July contain little that the company could use to either attack its competitors or defend its own products.

Bundles of patents covering computing—especially mobile computing—technology have become a hot property in recent months. Apple, Nokia, Microsoft, and others have used them to extract money from competitors, or even to block those competitors' products from being sold. This year, Apple successfully prevented the sale of some Samsung devices in much of Europe, while Microsoft has used patents to extract millions of dollars in licensing fees, from companies including Samsung and HTC, for using Google's "free" Android operating system.

In August, Google announced it planned to buy Motorola's cell-phone business, Motorola Mobility, for $12.5 billion. That company's patent portfolio was key to the deal—Google CEO Larry Page said it would "better protect Android from anticompetitive threats from Microsoft, Apple, and other companies."

Hoo-Min Toong, cofounder of IPVision, says, "It's common knowledge that Google is patent poor. Not only does it need to gain patents in their own product areas, but also in defending themselves against other claims."

Google is young compared to many of its rivals, without decades of research and patent filings, unlike competitors such as Apple. Toong says Google's current stock of patents is not only small, but it also relates to fundamental search technologies and techniques, rather than competitive areas such as mobile software.

At first glance, the patents Google bought from IBM look good. The U.S. patent office maintains a set of subject categories used to sort patents, and most of those acquired from IBM spread across the "700 series," where new software ideas and techniques are to be found.

This image, created by IPVision, shows how that contrasts with Google's prior patent portfolio, which is concentrated in just one category related to database and information retrieval techniques used in search. "This looks good in that I'm getting patents that strengthen my position and could be used against other companies," says Toong. "But if you look under the covers, things aren't so good." 

Patent filings must reference previous, related patents, making it possible for IPVision to calculate whether a collection of patents contain clusters that are highly connected—what is termed a "patent thicket." Such clusters, combined with strong "families" of patents filed on different aspects of the same technology, make it easier to mount a bulletproof assertion in court that a competitor's technology infringes on a company's intellectual property.