Apple, along with several other companies, is facing a new patent infringement lawsuit over the iPhone's ability to move between cell towers when making calls. The patent in question was originally owned by British Telecom, but has since been acquired by the patent holding company Steelhead Licensing.
Steelhead Licensing buys BT patent, then sues Apple
Patent 5,491,834 titled "mobile radio handover initiation determination," describes the process where a cell signal jumps from one tower to another for better reception. The patent covers both 3G and 4G signals.
The patent abstract states,
An intelligent mobile radio unit is served by one of a network of macrocells and microcells. The unit is arranged to monitor, for example, the signal strength or bit error ratio of signals transmitted from each of a set of candidate base stations of cells surrounding the serving base based on the assessment of a running average of the rise/fall in signal quality, the unit is arranged to determine from a look-up table of stored templates of conditions for handover whether a handover between base stations and between macro- and microcells.
Steelhead Licensing is also suing HTC, Motorola Mobility, RIM, Sony, LG, Kyocera, NEC, Pantech, and ZTE for infringing on the patent. Cell service providers AT&T, T-Mobile, Sprint, Nextel and Metro PCS were named in lawsuits as well.
The BT patent was filed in 1993 and granted in 1996, and seems to describe one of the basic components of cell service functionality: the ability to move from cell tower to cell tower for better signal reception.
Steelhead filed its lawsuits in U.S. Federal Court in the District of Delaware. Apple has not commented on the filing.
[Thanks to RapidBerry for the heads up.]