CISCO SYSTEMS, INC. v. TQ DELTA, LLC., decided July 10, 2019, Claim Interpretation

U.S. Patent No. 8,611,404 is directed to sleep state in a multicarrier system (page 2). “Synchronization signal” appears only in the claims (page 4), and the specification describes a tone, referred to as a timing reference signal for synchronization (page 4). The specification also teaches frame synchronization (page 9). “Synchronization signal” was incorrectly interpreted to be a signal for synchronization between a clock of the transmitter and a clock of a receiver, not a frame (page 6). The specification does not indicate what must be synchronized or type of synchronization (page 7). Both frame and frequency synchronization are taught (pages 8-9), so frame synchronization is included (pages 9-10).

Hindsight: “Signal” and “data” may not be interchangeable. It may be best to use generics, such as synchronization information, to avoid risk of interpretation of signal not being data or data not being an analog signal.