Sisvel International S.A. v. Sierra Wireless Inc.
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Decoding Algorithms: Structural Sufficiency for Means-Plus-Function Claim Judged From Skilled Artisan’s Perspective

The US Court of Appeals for the Federal Circuit reiterated that in the context of construing computer-implemented means-plus-function limitations, if the specification discloses some arguable algorithm, even if a party contends that the algorithm is inadequate, the sufficiency of the purportedly-adequate structure disclosed in the specification must be evaluated in light of the knowledge possessed by a skilled artisan. Sisvel International S. A. v. Sierra Wireless, Inc., Case No. 22-1493 (Fed. Cir. Oct. 6, 2023) (Moore, Clevenger, Chen, JJ.)

Sisvel owns a patent directed to methods of channel coding when transmitting data in radio systems. The patent uses techniques called “link adaptation” and “incremental redundancy,” which are alleged to provide improvement over prior channel coding techniques. Sierra filed a petition for inter partes review (IPR) challenging certain claims as obvious over the Chen reference by itself and challenging those and other claims as obvious over the combination of the Chen and Eriksson references or the combination of the Chen and GSM references. The Patent Trial & Appeal Board found that some challenged claims were obvious based on Chen alone and that other claims were patentable over the proposed combination of references. Both parties appealed.

Sisvel appealed the Board’s unpatentability finding, arguing that Chen failed to disclose a second puncturing pattern. Sisvel also argued that the Board did not provide a sufficiently detailed explanation to support its finding that Chen disclosed the claimed “combining” limitation and ignored Sisvel’s rebuttal arguments. The Federal Circuit disagreed with Sisvel on both counts and affirmed the Board’s determination. Regarding the second puncturing pattern, the Court found that the independent claim required a “first puncturing pattern” and a “second puncturing pattern,” and that Chen expressly described that its coded transmissions are “generated by using punctured codes” and that “[p]uncturing reduces the number of code symbols to be retransmitted.” Therefore, the Court found that substantial evidence supported the Board’s finding that Chen taught a second puncturing pattern. Regarding the “combining” limitation, the Court affirmed the Board’s decision and concluded that Chen’s disclosure of “accumulating the code symbols from the transmitted and retransmitted coded data blocks,” also referred to in Chen as “interleaving,” taught the “combining” limitation. Overall, the Court determined that the Board’s analysis was sufficiently detailed, adequately addressed Sisvel’s related arguments and was supported by substantial evidence.

Sierra appealed the patentability finding, arguing that the Board’s finding that a skilled artisan would not have been motivated to combine Chen and the GSM references was not supported by substantial evidence. Sierra also argued that the Board erroneously found insufficient corresponding structure in the specification for the term “means for detecting.” The Federal Circuit concluded that substantial evidence supported the Board’s finding of a lack of motivation to combine Chen and the GSM references, but that the Board erred in analyzing the “means for detecting” limitation. Regarding motivation to combine, the Court explained that although an IPR petitioner has a low burden of explaining why a skilled artisan would have been motivated to combine various references to form [...]

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Less Is More: IPR Claim Amendments May Not Enlarge Claim Scope

The US Court of Appeals for the Federal Circuit affirmed a decision from the Patent Trial & Appeal Board denying a motion to amend claims during an inter partes review (IPR) proceeding, explaining that a claim amendment is improper if a proposed claim is broader in any respect relative to the original claims, even if it is overall narrower. Sisvel International S.A. v. Sierra Wireless, Inc., et al., Case Nos. 22-1387; -1492 (Fed. Cir. Sept. 1, 2023) (Prost, Reyna, Stark, JJ.)

Sisvel owns two patents directed to methods and apparatuses that rely on the exchange of frequency information in connection with cell reselection between a mobile station (or user cell phone) and a central mobile switching center. Sierra Wireless filed petitions for IPR alleging that claims of Sisvel’s patents were unpatentable as anticipated and/or obvious in view of certain prior art. During the IPR proceeding, the Board determined that the claim term “connection rejection message” should be given its plain and ordinary meaning of “a message that rejects a connection.”

The Board also denied Sisvel’s motion to amend the claims of one of the patents, finding that the amendments would have impermissibly enlarged the claim scope. the Board focused on a limitation relating to “setting a value,” comparing the original claims’ requirement with that of the proposed substitute claims. The original claims required that the value be set “based at least in part on information in at least one frequency parameter” of the connection rejection message while the substitute claims recited that the value may be set merely by “using the frequency parameter” contained within the connection rejection message. The Boeasoneasoned that in the proposed substitute claim, the value that is set need not be based on information in the connection rejection message, and thus the claim was broader in this respect than the original claims. After denying the motion to amend, the Board concluded that the original claims were unpatentable. Sisvel appealed.

Sisvel challenged the Board’s construction of “connection rejection message,” arguing that the term should be limited to a message from the specific cellular networks disclosed in the specification. The Federal Circuit rejected Sisvel’s argument, finding that the intrinsic evidence provided no persuasive basis to limit the claims to any particular cellular network disclosure. Having agreed with the Board’s construction, the Court affirmed the unpatentability determination.

Sisvel also challenged the Board’s refusal to permit Sisvel to amend the claims. Sisvel argued that the Board had incorrectly found that the proposed substitute claims were broader than the original claims because when all the limitations were considered as a whole, the scope of the substitute claims was narrower than the original claims.

Citing 35 U.S.C. § 316(d)(3), the Federal Circuit noted that when a patent owner seeks to amend its claims during an IPR, the amended claims “may not enlarge the scope of the claims of the patent.” The Court explained that removal of a claim requirement can broaden the resulting amended claim and concluded that such was the case [...]

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