Lucent has filed suit against Microsoft for patent infringement over technology used in its Xbox 360 game console.
At the centre of the dispute is Patent Number 5,227,878, 'Adaptive Coding and Decoding of Frames and Fields of Video,' issued by the US Patent and Trademark Office (USPTO) to Lucent on July 19, 1993, according to court papers filed March 28 by the company.
Lucent claims Microsoft is using its patented technology in the Xbox 360's built-in MPEG-2 decoding capability.
Microsoft released the Xbox 360 game console in the US last November; it is now available in more than 15 countries.
This is not the first time Lucent and Microsoft have sparred legally over the patent. In a previous suit filed in 2003, the tables were turned, with Microsoft suing Lucent in an effort to seek a judgment of non-infringement, according to court papers. The company was successful; a judge last year granted summary judgment in Microsoft's favour because of a typographical error in the patent.
Lucent has since corrected the error with the USPTO and received an official patent correction notice, according to last week's filing.
Before taking its latest legal action, Lucent notified Microsoft of what it believes is "willful" infringement of its patent, but did not cease distribution or production of the Xbox 360, according to papers filed by Lucent.
Lucent is seeking unspecified damages from Microsoft and is requesting a jury trial to resolve the suit.
Neither Lucent nor Microsoft responded to requests for comment.