Another day, another patent-infringement suit in the world of mobile handset manufacturers.

Nokia filed a complaint against Apple in a Federal District Court in western Wisconsin, arguing that Apple’s iPhone and iPad infringe on five of its patents. The Finnish handset maker last sued Apple for patent infringement in October.

This legal move comes two months after Apple sued Taiwan’s HTC, maker of Google’s Nexus One phone, for imposing on its intellectual property rights.

“We have taken this step to protect the results of our pioneering development and to put an end to continued unlawful use of Nokia’s innovation,” said Paul Melin, General Manager, Patent Licensing at Nokia.

The patents Nokia says Apple is violating relate to “enhanced speech and data transmission, using positioning data in applications and innovations in antenna configurations that improve performance and save space, allowing smaller and more compact devices.”

The company said it has invested the equivalent of $51 billion in research and development and has rounded up 11,000 patents.

Don’t miss MobileBeat 2010, VentureBeat’s conference on the future of mobile. The theme: “The year of the superphone and who will profit.” Now expanded to two days, MobileBeat 2010 will take place on July 12-13 at The Palace Hotel in San Francisco. Early-bird pricing is available until May 15. For complete conference details, or to apply for the MobileBeat Startup Competition, click here.