Google ended the year by doing a little patent shopping from IBM's vast portfolio, acquiring 217 patents from the technology giant, in what is likely an effort to further strengthen its Android platform in the face of increased pressure from rivals as it soars in popularity.

The search giant bought 188 granted patents and 29 published pending patent applications, according to SEO by the Sea. The deal was completed during the last week of December, with the patent office recording the exchange on the 30th. The cost to Google is unknown, and if previous deals are anything to go by, it's unlikely we'll ever know all the finer details of the acquisition.

"The patents cover a broad range of topics, such as presentation software, blade servers, data caching, server load balancing, network performance, video conferencing, email administration, and instant messaging applications. A number of the patents cover specific internet, phone, and mobile phone technologies as well," SEO by the Sea reported.

The two firms have been busy with patent transactions over the last year. In July, Google purchased 1,030 patents from IBM. August saw the firm purchase a further 1,022, and in September another 41 patents. This new deal brings the total number of patents purchased from IBM in 2011 to 2,310.

Last year also saw Google ramping up business acquisitions to increase its portfolio, with the proposed purchase of Motorola Mobility set to add the phone manufacturer's estimated 24,000 strong portfolio to their arsenal. Both firms are currently awaiting industry approvals, with the $12.5 billion deal due to close in the first quarter of this year.

All these purchases may well come in handy as well, with the recent news that British Telecom has filed lawsuits against Android for what it claims are six key infringements of the British communication firm's patents. The company is said to be demanding billions in compensation and future royalties.