Moore Vacates PTAB Finding That Some Sisvel Data Transmission Patent Claims Are Obvious

The Chief Judge of the U.S. Court of Appeals for the Federal Circuit (CAFC), Kimberly Moore, on Monday authored a short precedential decision vacating and remanding a Patent Trial and Appeal Board (PTAB) decision that had found certain claims of Sisvel’s data transmission patent to be unpatentable.

Sisvel’s U.S. Patent No. 7,869,396 is titled, “Data Transmission Method and Data Re-transmission Method.” Sierra Wireless, ULC petitioned for inter partes review (IPR) of all ten claims of the patent, claiming they were anticipated by and obvious in view of an International Patent Application Publication called “Sachs”. The Board ultimately held claims 1, 2, and 6–8 to be unpatentable as anticipated by and obvious in view of Sachs but held claims 3–5, 9, and 10 were not shown to be unpatentable. Sierra Wireless appealed the finding that the latter claims were not shown to be unpatentable and Sisvel cross-appealed the finding of unpatentability.

The CAFC’s opinion first addressed the cross-appeal, explaining that it agreed with Sisvel’s argument that the Board erred in holding the claims unpatentable because it 1) “erroneously construed limitations 1[c] and 1[d] as conditional” and 2) “the Board’s finding that Sachs discloses limitation 1[c] is not supported by substantial evidence.”

The language of the limitations in question are as follows:

“1. [pre] A method of performing automatic repeat request (ARQ) in a wireless communication system, the method performed by a receiver and comprising:

[c] stopping the timer when the at least one data block is received from the transmitter while the timer is running, in order to prevent a triggering of a status report before the timer expires; and

[d] transmitting the status report to the transmitter after the timer expires, wherein the status report comprises a positive acknowledgement indicating receipt of at least one received data block.”

The PTAB held that limitations 1[c] and 1[d] were “mutually exclusive,” wrote the CAFC, because they “‘cannot both occur in response to the same set of stimuli’ because the timer either stops upon receipt of the missing PDU (as required by limitation 1[c]) or expires without having received the missing PDU (as required by limitation 1[d]), but it cannot do both.” Thus, the prior art would “need only to disclose limitations 1[a], 1[b], and 1[c] or limitations 1[a], 1[b], and 1[d] to anticipate claim 1,” according to the Board.

However, the CAFC said “[t]hat conclusion does not follow from the premise describing the claim language.” Instead, the court said “the plain and unambiguous language of claim 1 requires that a method, to come within the claim, must perform both limitations 1[c] and 1[d] where their preconditions apply.”

As to Sierra Wireless’ appeal, the court’s decision to vacate the unpatentability finding on the independent claims made it unnecessary to reach the appellants’ arguments regarding the dependent claims. However, the CAFC did  agree with Sierra Wireless that the Board abused its discretion in relying on Sisvel’s expert testimony to reach its finding that unpatentability was not shown, since the expert did not qualify as a skilled artisan according to the Board’s definition.

The PTAB “found a skilled artisan to the ’396 patent “would have had a degree in electrical engineering or a similar discipline, with at least three years of relevant industry or research experience, including experience designing or implementing wireless radio systems for data transmission and retransmission,’” explained the opinion. Sisvel’s expert did not have a degree in electrical engineering “or any other engineering or science discipline,” and his decades of professional experience did not specifically include “designing the channels and methods for transmitting and retransmitting data in a cellular network.” Thus, “[w]hether Mr. Bates’ experience suffices to meet the requirements for a person of skill in the art is a question of fact that we will not decide in the first instance, and we thus vacate for Board consideration of this issue,” said the CAFC.