HTC has suffered a further blow in its patent battle against rival Nokia. According to a CNA report, the District Court of Mannheim, Germany ruled January 31 that the Taiwanese smartphone maker had infringed on Nokia's wireless patent EP1579613 for a "method and apparatus for enabling a mobile station to adapt its revision level based on network protocol revision level".

The patent in question is not a standard-essential patent and deals with backward compatibility between new devices and networks running older technologies. In a filing to the Taiwan Stock Exchange on Saturday, HTC noted that the functionality was redundant, and no longer used in Germany. The company said that they're already investigating the required modifications and that any changes made would cause minimal disruption to customers while the company pursues an appeal.

On the other hand, Nokia seems pleased with the ruling, which not only refrains HTC from importing and selling of all its infringing products in Germany, but also asks the Taiwanese smartphone maker to provide damages for past infringement.

This is Nokia's fourth victory in its German patent lawsuits against HTC. Since 2012, when Nokia filed its first patent infringement against HTC, the Finnish company has asserted more than 50 patents globally against HTC. Regional courts in Germany, United Kingdom, as well as the U.S. International Trade Commission, have concluded that the Taiwanese smartphone maker did infringe on several Nokia patents.