Case: 23-1059 Document: 91 Page: 1 Filed: 03/10/2025

United States Court of Appeals for the Federal Circuit ______________________

SIERRA WIRELESS, ULC, HONEYWELL INTERNATIONAL INC., TELIT CINTERION DEUTSCHLAND GMBH F/D/B/A THALES DIS AIS DEUTSCHLAND GMBH, Appellants

v.

SISVEL S.P.A., Cross-Appellant ______________________

2023-1059, 2023-1085, 2023-1089, 2023-1125 ______________________

Appeals from the United States Patent and Trademark Office, Patent Trial and Appeal Board in No. IPR2021- 00580. ______________________

Decided: March 10, 2025 ______________________

KOURTNEY MUELLER MERRILL, Perkins Coie LLP, Den- ver, CO, argued for all appellants. Appellant Sierra Wire- less, ULC also represented by AMANDA TESSAR; TARA LAUREN KURTIS, Chicago, IL.

ROBERT J. GAJARSA, Devlin Law Firm LLC, Wilming- ton, DE, argued for cross-appellant. Also represented by NEIL A. BENCHELL, TIMOTHY DEVLIN, NADIIA LOIZIDES. Case: 23-1059 Document: 91 Page: 2 Filed: 03/10/2025

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JEFFREY R. GARGANO, K&L Gates LLP, for appellant Honeywell International Inc. Also represented by BRIAN PAUL BOZZO, Pittsburgh, PA; ERIK HALVERSON, San Fran- cisco, CA.

GUY YONAY, Pearl Cohen Zedek Latzer Baratz LLP, New York, NY, for appellant Telit Cinterion Deutschland GmbH. Also represented by KYLE AUTERI, I. ______________________

Before MOORE, Chief Judge, SCHALL and TARANTO, Circuit Judges. MOORE, Chief Judge. Sierra Wireless, ULC; Honeywell International Inc.; and Telit Cinterion Deutschland GmbH (collectively, Ap- pellants) appeal a final written decision of the Patent Trial and Appeal Board (Board) holding claims 3–5, 9, and 10 of U.S. Patent No. 7,869,396 were not shown to be unpatent- able. Sisvel S.p.A. (Sisvel) cross-appeals the Board’s hold- ing that claims 1, 2, and 6–8 of the ’396 patent are unpatentable. For the following reasons, we vacate and re- mand. BACKGROUND Sisvel owns the ’396 patent, which relates to “a data transmission method and a data retransmission method which can reduce loss in data transmission” in a wireless communication system. ’396 patent at 1:17–20. Data is packaged into protocol data units (PDUs) for transmission. Id. at 6:48–52. PDUs are typically assigned sequence num- bers to help the receiver detect missing PDUs and place received PDUs in sequential order. Id. at 5:4–6; J.A. 1128– 29 ¶ 70. Prior art techniques for reducing data loss include the automatic repeat request (ARQ) method, in which a re- ceiver sends a message to a transmitter if an expected PDU is not received, allowing the transmitter to retransmit the missing PDU. ’396 patent at 1:58–2:5. Case: 23-1059 Document: 91 Page: 3 Filed: 03/10/2025

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The ’396 patent claims a variation of the ARQ method that aims to increase reliability and efficiency. Id. at 2:11– 13. In the claimed method, the receiver activates a timer when a PDU is detected as missing. Id. at 14:28–30. If the missing PDU is not received before the timer expires, a re- ception failure is detected and reported to the transmitter. Id. at 14:30–34. If the missing PDU is received before the timer expires, the timer is stopped. Id. at 14:38–46. Claims 1 and 8 are the only independent claims. Claim 1 reads: 1. [pre] A method of performing automatic repeat request (ARQ) in a wireless communication sys- tem, the method performed by a receiver and com- prising: [a] detecting whether at least one data block to be received from a transmitter is missed; [b] starting a timer when the at least one data block is detected as missed; [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 transmit- ter after the timer expires, wherein the status re- port comprises a positive acknowledgement indicating receipt of at least one received data block. Id. at 16:39–53 (emphasis and bracketed labels added). As relevant here, Appellants petitioned for inter partes review of the ’396 patent, challenging all ten claims as an- ticipated by and obvious in view of International Patent Application Publication No. WO 02/091659 (Sachs). The Board, in a divided opinion, held claims 1, 2, and 6–8 to be unpatentable as anticipated by and obvious in view of Case: 23-1059 Document: 91 Page: 4 Filed: 03/10/2025

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Sachs. The Board held claims 3–5, 9, and 10 were not shown to be unpatentable. Appellants appeal the Board’s holding as to claims 3–5, 9, and 10 and argue the Board abused its discretion by relying on testimony from Sisvel’s declarant, Regis Bates. Sisvel cross-appeals the Board’s holding as to claims 1, 2, and 6–8. We have jurisdiction under 28 U.S.C. § 1295(a)(4)(A). DISCUSSION We review the Board’s legal conclusions de novo and its factual findings for substantial evidence. Redline Detec- tion, LLC v. Star Envirotech, Inc., 811 F.3d 435, 449 (Fed. Cir. 2015). Anticipation is a question of fact. Blue Calypso, LLC v. Groupon, Inc., 815 F.3d 1331, 1341 (Fed. Cir. 2016). Obviousness is a question of law based on underlying find- ings of fact. In re Gartside, 203 F.3d 1305, 1316 (Fed. Cir. 2000). What a prior art reference discloses is a question of fact. Adasa Inc. v. Avery Dennison Corp., 55 F.4th 900, 910 (Fed. Cir. 2022). The level of ordinary skill in the art is a question of fact. Arctic Cat Inc. v. Bombardier Recreational Prods. Inc., 876 F.3d 1350, 1358 (Fed. Cir. 2017). I. Sisvel’s Cross-Appeal: Claims 1, 2, and 6–8 Sisvel argues the Board erred in holding claims 1, 2, and 6–8 to be unpatentable as anticipated and obvious based on Sachs. Sisvel Br. 65–75. First, Sisvel argues the Board erroneously construed limitations 1[c] and 1[d] as conditional. Second, Sisvel argues the Board’s finding that Sachs discloses limitation 1[c] is not supported by substan- tial evidence. We agree with Sisvel on both counts. The Board held limitations 1[c] and 1[d] are mutually exclusive. That is, 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 re- quired by limitation 1[d]), but it cannot do both. J.A. 16– 17. On that basis, the Board held the prior art need only Case: 23-1059 Document: 91 Page: 5 Filed: 03/10/2025

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disclose limitations 1[a], 1[b], and 1[c] or limitations 1[a], 1[b], and 1[d] to anticipate claim 1. Id. That conclusion does not follow from the premise describing the claim lan- guage. While the canons of claim construction teach that claims should be construed to preserve their presumed va- lidity, this is “[i]f, after applying all other available tools of claim construction, a claim is ambiguous.” Ruckus Wire- less, Inc. v. Innovative Wireless Sols., LLC, 824 F.3d 999, 1004 (Fed. Cir. 2016). Here, we reject the Board’s conclu- sion because 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 precon- ditions apply. ’396 patent at 16:46–53 (“stopping the timer . . . and transmitting the status report after the timer expires” (emphasis added)). The Board found Sachs Figure 5 discloses “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” (limitation 1[c]): Case: 23-1059 Document: 91 Page: 6 Filed: 03/10/2025

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J.A. 1295; J.A. 13–19. The Board relied on Sachs’ teaching that “[i]n a preferred embodiment the timer is stopped be- fore the timer expiry when at the reception of a data packet the sequence is established.” J.A. 17–18 (quoting J.A. 1275–76 at 9:34–10:1). The Board found Sachs discloses limitation 1[c] because the timer in Figure 5 is stopped upon receipt of any missing PDUs, and not after the occur- rence of some separate reordering procedure. J.A. 17–18. The Board’s finding that Sachs Figure 5 discloses limi- tation 1[c] is not supported by substantial evidence. Sachs itself explains that Figure 5 depicts stopping the T_reorder timer after PDUs have been put into sequential order. In- deed, the portion of Sachs on which the Board relied ex- plains “the timer is stopped before the timer expiry when at the reception of a data packet the sequence is estab- lished.” J.A. 17 (quoting J.A. 1275–76 at 9:34–10:1) (em- phasis modified). In its description of the invention, Sachs states “the reo[r]dering-delay shall preferably be stopped when all outstanding PDUs are received and the sent se- quence is re-established. This can be achieved by stopping the duration of the T_reorder timer, when reordering is fin- ished. This embodiment is shown in figure 5.” J.A. 1280 at 14:2–6 (emphasis added). Figure 5 itself is clearly la- beled “stop timer when re-ordering is finished.” J.A. 1295. Appellants’ own declarant, Dr. Apostolos Kakaes, opined that according to Sachs Figure 5, the timer stops after reordering and not upon receipt of the missing PDUs: The timer continues until the [Radio Link Control (RLC)] receiver receives each of the expected but missing PDUs: 1, 2, 3, and 4 (which includes spe- cifically PDU4) and thus has a complete, correctly ordered subset, i.e., 1, 2, 3, 4, 5, 6, 7, and 8. When that occurs, Figure 5 explains to ‘stop timer when re-ordering is finished.’ Here, Sachs refers to the reordering of the received PDUs in sequential or- der in the buffer. Case: 23-1059 Document: 91 Page: 7 Filed: 03/10/2025

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J.A. 1172–73 ¶ 154; see J.A. 233. Sisvel argued that Sachs does not disclose limitation 1[c] because “Figure 5 discloses stopping a timer, but only when reordering is finished.” J.A. 515. Oddly, Appellants replied by citing this same par- agraph of Dr. Kakaes’ declaration that states the T_reorder timer stops when reordering is finished. J.A. 622 (citing J.A. 1172–73 ¶ 154). The Sachs reference and evidence from both parties indicate that the T_reorder timer of Sachs Figure 5 is stopped when reordering is finished, ra- ther than when missing PDUs are received. Therefore, the Board’s fact finding to the contrary is not supported by sub- stantial evidence. Because the Board’s fact finding that Figure 5 discloses limitation 1[c] is not supported by substantial evidence, we vacate the Board’s holdings that claim 1 is anticipated by and obvious in view of Sachs and its holdings regarding claims 2 and 6–8, which incorporate this same erroneous finding. See J.A. 20–22, 32–34. II. Appellants’ Appeal: Claims 3–5, 9, and 10 Appellants appeal the Board’s determination that de- pendent claims 3–5, 9, and 10 were not shown to be un- patentable. Because we vacate the Board’s findings of unpatentability of the independent claims, we need not reach the Appellants’ arguments regarding dependent claims 3–5, 9 and 10. We do, however, agree with Appel- lants that the Board abused its discretion by relying on the testimony of Sisvel’s expert Mr. Bates, absent a finding that he is qualified as an ordinarily skilled artisan. “To offer expert testimony from the perspective of a skilled artisan in a patent case—like for claim construc- tion, validity, or infringement—a witness must at least have ordinary skill in the art.” Kyocera Senco Indus. Tools Inc. v. Int’l Trade Comm’n, 22 F.4th 1369, 1376–77 (Fed. Cir. 2022). We review the Board’s evidentiary determina- tions, including the credibility of expert testimony, for abuse of discretion. See Shoes by Firebug LLC v. Stride Case: 23-1059 Document: 91 Page: 8 Filed: 03/10/2025

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Rite Children’s Grp., LLC, 962 F.3d 1362, 1372 (Fed. Cir. 2020). “The Board abuses its discretion if its decision (1) is clearly unreasonable, arbitrary, or fanciful; (2) is based on an erroneous conclusion of law; (3) rests on clearly errone- ous fact finding; or (4) involves a record that contains no evidence on which the Board could rationally base its deci- sion.” ClearOne, Inc. v. Shure Acquisition Holdings, Inc., 35 F.4th 1345, 1351 (Fed. Cir. 2022) (internal quotation marks and citation omitted). Appellants argue the Board abused its discretion by crediting Sisvel’s declarant, Mr. Bates, because he was not a skilled artisan under the Board’s definition. Appellants Br. 62–64. The Board 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 de- signing or implementing wireless radio systems for data transmission and retransmission.” J.A. 8. Mr. Bates lacks a technical degree in electrical engineering or any other en- gineering or science discipline. J.A. 3138 ¶ 7. His profes- sional experience relates to “designing, building, optimizing and training others in many aspects of telecom- munications systems,” J.A. 3138 ¶ 8, but does not specifi- cally include “designing the channels and methods for transmitting and retransmitting data in a cellular net- work,” J.A. 3091 at 45:18–46:16. Mr. Bates’ experience does not, on its face, satisfy the Board’s requirements for a skilled artisan. Mr. Bates’ declarations opine on anticipa- tion and obviousness, issues that must be examined from the perspective of a skilled artisan. J.A. 3157–62 (declara- tion of Mr. Bates); J.A. 3209–15 (second declaration of Mr. Bates); Wasica Fin. GmbH v. Cont’l Auto. Sys., Inc., 853 F.3d 1272, 1284 (Fed. Cir. 2017) (“Anticipation is an in- quiry viewed from the perspective of one skilled in the art.”); HVLPO2, LLC v. Oxygen Frog, LLC, 949 F.3d 685, 688 (Fed. Cir. 2020) (“Obviousness and each of its underly- ing components are analyzed from the perspective of a Case: 23-1059 Document: 91 Page: 9 Filed: 03/10/2025

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person of skill in the art.”). The Board cited and relied upon Mr. Bates’ testimony throughout its anticipation and obvi- ousness analyses. See, e.g., J.A. 24, 26, 28, 30. Appellants contend the Board’s failure to provide reasoning for its de- cision to credit Mr. Bates’ testimony was an abuse of dis- cretion. We agree. Sisvel argues Mr. Bates has decades of experience in the telecommunications field, which more than suffices to satisfy the engineering degree required by the Board’s or- dinarily skilled artisan finding. Sisvel Br. 62–64. The Board, however, made no such determination regarding whether Mr. Bates qualifies as a skilled artisan despite his lack of credentials specified in the Board’s definition. Whether Mr. Bates’ experience suffices to meet the require- ments 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. CONCLUSION For the foregoing reasons, we vacate the Board’s hold- ing that claims 1, 2, and 6–8 are unpatentable as antici- pated by and obvious in view of Sachs. We hold that the Board abused its discretion by relying on Mr. Bates’ testi- mony where he does not satisfy the requirements for an or- dinarily skilled artisan and the Board made no finding that his years of experience were sufficient to establish that he was at least an ordinarily skilled artisan. Because we va- cate on Sisvel’s cross-appeal, which includes the independ- ent claims, we need not reach Appellants’ appeal regarding the patentability of dependent claims 3–5, 9, and 10. We remand for further proceedings consistent with this opin- ion. VACATED AND REMANDED COSTS No costs.