Motorola has launched the next offensive in an increasingly confusing legal war over mobile patents. The company, through its Motorola Mobility subsidiary, has filed patent infringement complaints against Apple in both Northern Illinois and Southern Florida federal district courts. It has also asked the International Trade Commission to block Apple from importing, marketing, or selling iPhones, iPads, iPod touches, and "some Mac products."

Motorola's four complaints involve a total of 18 patents, which the company says covers everything from 3G, GPRS, and 802.11 technologies, antenna design, proximity sensing, device synchronization, and more. Motorola also says that everything from the hardware on up to iOS, MobileMe, and the App Store infringes upon its patented innovations.

"We have extensively licensed our industry-leading intellectual property portfolio, consisting of tens of thousands of patents in the US and worldwide," Kirk Dailey, Motorola Mobility's corporate vice president of intellectual property, said in a statement. "After Apple's late entry into the telecommunications market, we engaged in lengthy negotiations, but Apple has refused to take a license. We had no choice but to file these complaints to halt Apple's continued infringement."

The patents in question (listed below) are divided among three separate lawsuits. Six of them—'333, '862, '697, '317, '223, and '826—are also named in the parallel complaint filed with the ITC.

• 5,311,516: Paging system using message fragmentation to redistribute traffic
• 5,319,712: Method and apparatus for providing cryptographic protection of a data stream in a communication system
• 5,490,230: Digital speech coder having optimized signal energy parameters
• 5,572,193: Method for authentication and protection of subscribers in telecommunication systems
• 6,175,559: Method for generating preamble sequences in a code division multiple access system
• 6,359,898: Method for performing a countdown function during a mobile-originated transfer for a packet radio system
• 5,359,317: Method and apparatus for selectively storing a portion of a received message in a selective call receiver
• 5,636,223: Methods of adaptive channel access attempts
• 6,246,697: Method and system for generating a complex pseudonoise sequence for processing a code division multiple access signal
• 6,246,862: Sensor controlled user interface for portable communication device
• 6,272,333: Method and apparatus in a wireless communication system for controlling a delivery of data
• 7,751,826: System and method for E911 location privacy protection
• 5,710,987: Receiver having concealed external antenna
• 5,754,119: Multiple pager status synchronization system and method
• 5,958,006: Method and apparatus for communicating summarized data
• 6,008,737: Apparatus for controlling utilization of software added to a portable communication device
• 6,101,531: System for communicating user-selected criteria filter prepared at wireless client to communication server for filtering data transferred from host to said wireless client
• 6,377,161: Method and apparatus in a wireless messaging system for facilitating an exchange of address information

The multiple lawsuits come just days after Microsoft launched a major patent infringement suit against Motorola, claiming its Android-based smartphones infringe on nine of its patents. Android has also been the target of a lawsuit levied by Oracle against Google over the use of Java. Patent infringement claims are also pending between Apple and HTC, Apple and Nokia, and numerous other companies competing in the smartphone space.

While many of these lawsuits could take several years to wind their way through the courts, it has become clear that patent licensing has become an enormous legal albatross for anyone attempting to build and sell a smartphone in this burgeoning market. Given the stakes involved—smartphones are one of the biggest consumer electronics segments by sales revenue—we expect a protracted fight, and it's hard to imagine the outcome will be pretty.