Apple, Research in Motion (RIM) and Motorola Mobility are among 15 companies sued in the U.S. over a fundamental 3G and 4G patent on determining when devices should switch cells in a mobile network.
The suits were filed by Steelhead Licensing on Friday, in the U.S. District Court for the District of Delaware. Besides Apple, RIM and Motorola, Steelhead also sued handset makers HTC, LG Electronics, Kyocera, NEC Casio Mobile, Pantech, Sony and ZTE, and wireless network operators AT&T, MetroPCS, Sprint Nextel, Verizon Wireless and Deutsche Telekom (T-Mobile USA), court documents showed.
Apple's iPhone 5, HTC's Windows Phone 8X, and Motorola Mobility's Droid X and Razr, as well as two of RIM's BlackBerry Curve models, are among the allegedly infringing devices. The wireless operators allegedly infringe with the JetPack 4G Hotspot (Verizon), the SonicMobile 4g Hotspot (T-Mobile) and the AT&T Mobile Hotspot Elevate 4G, as well as with several phones, according to the filings.
The patent in suit includes a process for determining the manner in which handover is performed in a mobile radio network, including a plurality of cells, where each cell is associated with a base station supporting communication with a mobile device, Steelhead said in the documents.
"In mobile telephony, it is necessary to maintain an established user connection even if the user is changing locations, or the radio access environment surrounding the user is changing, while the connection is still active," the company said, adding that "handover" refers to the transfer of user connection from one access point to another.
The products named in the suits rely on the patented process to determine mobile device communication conditions for initiating a handover from one cell to another, Steelhead said.
The U.S. Patent and Trademark Office (USPTO) still lists the patent as assigned to U.K. network operator BT. However Steelhead, in its court filings, stated it is now the owner of the patent, and has the exclusive right to recover for past infringement.
BT did not immediately reply to a request for comment.
LG was also sued over a similar patent titled "Mobile radio handover determination based on rise/fall of signal quality as a function of time", also assigned to BT. Steelhead presently owns this patent, including the exclusive right to recover for past infringement it said.
Steelhead demanded a jury trial in all suits, asking for damages sufficient to compensate for past infringement and any continuing and future infringement.
Loek is Amsterdam Correspondent and covers online privacy, intellectual property, open-source and online payment issues for the IDG News Service. Follow him on Twitter at @loekessers or email tips and comments to email@example.com