Sisvel Int'l S.A. v. Sierra Wireless, Inc.

82 F.4th 1355

SISVEL INTERNATIONAL S.A., Appellant v. SIERRA WIRELESS, INC., Telit Cinterion Deutschland GmbH,f/d/b/a Thales Dis Ais Deutschland GmbH Cross-Appellants

2022-1493

2022-1547

United States Court of Appeals, Federal Circuit

Decided: October 6, 2023

Appeals from the United States Patent and Trademark Office, Patent Trial and Appeal Board in No. IPR2020-01099.

Robert J. Gajarsa, Devlin Law Firm LLC, Wilmington, DE, argued for appellant. Also represented by Timothy Devlin, Neil A. Benchell.

Kourtney Mueller Merrill, Perkins Coie LLP, Denver, CO, argued for all cross-appellants. Cross-appellant Sierra Wireless, Inc. also represented by Amanda Tessar.

Guy Yonay, Pearl Cohen Zedek Latzer Baratz LLP, New York, NY, for cross-appellant Telit Cinterion Deutschland GmbH. Also represented by Kyle Auteri, I.

Before Moore, Chief Judge, Clevenger and Chen, Circuit Judges.

Chen, Circuit Judge.

The Patent Trial and Appeal Board (Board) determined claims 1-3 and 9 of U.S. Patent No. 6,529,561 ('561 patent) were unpatentable, but upheld claims 4-8 and 10. Cradlepoint, Inc. v. Sisvel Int'l S.A., No. IPR2020-01099, 2021 WL 6655659, at *27 (P.T.A.B. Jan. 18, 2021) (Decision). Sisvel International S.A. (Sisvel) appeals the Board's unpatentability determination of claims 1-3 and 9; Sierra Wireless, Inc. and Telit Cinterion Deutschland GmbH (collectively, Cross-Appellants) appeal the Board's upholding of claims 4-8 and 10. As to the appeal, we affirm. As to the cross-appeal, we affirm-in-part, vacate-in-part, and remand.

BACKGROUND

I

The '561 patent relates to methods of channel coding when transmitting data in radio systems. '561 patent col. 1 ll. 10-15, col. 4 ll. 19-30. Channel coding is a technique that adds redundant information to a data block, thereby creating a coded data block. To account for problems from noise and interference during data transmission, the redundant data allows a receiver to more accurately detect and correct errors in the transmitted data, but at the cost of requiring more bandwidth and network resource usage.

The '561 patent uses techniques called "link adaptation" and "incremental redundancy," which it asserts improves prior channel coding techniques. Id. col. 3 ll. 2-5, col. 4 ll. 19-30. Link adaptation occurs on the transmission side and refers to changing the code rate¹ of the transmitted data blocks. Id. col. 1 ll. 39-41. A data block is first coded to add redundant data bits,² and then "punctured" to remove a certain number of coded data bits. Id. col. 7 ll. 21-46. In link adaptation, the code rate can be adjusted between successive data blocks to optimize radio resources based on channel conditions. Id. col. 1 ll. 39-50.

Incremental redundancy occurs on the receiver side. Id. col. 2 ll. 25-27. When a receiver receives a coded data block with too many errors to accurately decode, it will store that coded data block in memory and request retransmission of the data block. See id. col. 2 ll. 25-29. After receiving the retransmitted data block, the receiver combines the stored and the retransmitted coded data blocks. Id. col. 2 ll. 27-29. Because the combined coded data block has more overall data bits and increased redundancy, it can more feasibly be decoded by the receiver. Id. col. 2 ll. 29-33.

The claims recite coding a data block and then puncturing it with a first puncturing pattern to remove some data bits from the coded data block. The punctured, coded data block is then transmitted to a receiver. The receiver, however, may not be able to decode the data and requests retransmission. When the transmitter resends the coded data block, it performs link adaptation by changing the number of bits removed when puncturing the coded data block using a second puncturing pattern. Id. col. 1 ll. 39-41, col. 9 ll. 60-67. The second puncturing pattern removes more bits than the first puncturing pattern, such that the retransmitted coded data block transmits fewer bits. When the receiver receives the retransmitted coded data block, it performs incremental redundancy by combining the original and retransmitted coded data blocks and decoding the combined data block. Id. col. 9 ll. 65-67.

Independent claim 1 of the '561 patent recites:

1. A method of transmitting data in a radio system from a transmitter to a receiver, the method comprising:

channel coding a data block into a coded data block by using a selected channel coding;

puncturing the coded data block by using a first puncturing pattern;

transmitting the coded data block punctured by the first puncturing pattern to the receiver;

detecting a need for retransmission of the received coded data block;

transmitting a retransmission request of the coded data block to the transmitter;

increasing the code rate of the coded data block to be retransmitted by puncturing the coded data block coded by the channel coding of the original transmission using a second puncturing pattern including fewer symbols to be transmitted than the first puncturing pattern;

transmitting the coded data block punctured by the second puncturing pattern to the receiver;

combining the received coded data block punctured by the first puncturing pattern and the received coded data block punctured by the second puncturing pattern; and

decoding the channel coding of the combined coded data block.

Id. at claim 1 (emphasis added).

Claim 5 is similar to claim 1, but is directed to a radio system and further recites a "means for detecting" limitation³:

5. A radio system comprising:

a transmitter and a receiver having a radio connection to the transmitter; the transmitter comprising a channel coder for channel coding a data block into a coded data block by using a selected channel coding and for puncturing the coded data block by using a first puncturing pattern, and transmission means for transmitting the coded data block punctured by the first puncturing pattern to the receiver; and

the receiver comprising a channel decoder for decoding the received coded data block, means for detecting a need for retransmission of the received coded data block, and means for transmitting a retransmission request of the coded data block to the transmitter; wherein:

the channel coder increases the code rate of the coded data block to be retransmitted by puncturing the coded data block coded by the channel coding of the original transmission by using a second puncturing pattern comprising fewer symbols to be transmitted than the first puncturing pattern;

the transmission means transmit the coded data block punctured by the second puncturing pattern to the receiver;

the receiver comprises means for combining a received coded data block punctured by the first puncturing pattern and a received coded data block punctured by the second puncturing pattern; and

the channel decoder decodes the channel coding of the combined coded data block.

Id. at claim 5 (emphasis added).

II

Cross-Appellants filed a petition for inter partes review of claims 1-10 of the '561 patent. Decision, 2021 WL 6655659, at *1; J.A. 180. Relevant here, Cross-Appellants challenged claims 1-3, 5-7, 9, and 10 as unpatentable under 35 U.S.C. § 103 over Chen,⁴ as well as claims 1-10 as unpatentable under § 103 over Chen and Eriksson⁵ or Chen and GSM 03.64⁶.⁷ J.A. 186. The Board determined that Chen rendered claims 1-3 and 9 obvious, but upheld claims 4-8 and 10. Decision, 2021 WL 6655659, at *27.

First addressing claim 5's "means for detecting" limitation, the Board construed it as a means-plus-function limitation but determined there was "insufficient algorithmic structure identified" by Cross-Appellants in its petition. Id. at *5-6. The Board acknowledged Cross-Appellants' assertion that the "means for detecting" corresponded to various protocols mentioned by name in the '561 patent, such as forward error correction (FEC), Automatic Repeat Request (ARQ), and hybrid ARQ, and also acknowledged the related testimony from Cross-Appellants' expert, Dr. Kakaes. Id. at *3, *5-7. Dr. Kakaes testified that a skilled artisan would be familiar with "well-known and commonly used error detection codes, such as the" cyclic redundancy check (CRC) and "[ARQ] protocol and hybrid ARQ," and "would have known from the '561 specification how to program a processor or hardware to achieve the claimed function of 'detecting a need for retransmission of the received coded data block.' " Id. at *7. The Board, however, found that this testimony could not remedy the insufficient structure disclosed in the specification itself. Id. According to the Board, Cross-Appellants "ha[d] not shown that the '561 patent presents an algorithm for how the error detection code detects an error, nor explained the circumstances under which the error correcting code cannot correct errors and what constitutes 'sufficient certainty.' " Id. at *8.

Turning to Cross-Appellants' prior art challenges, the Board found that claims 1-3 and 9 would have been obvious in view of Chen. Relevant here, the Board found that Chen discloses both the "second puncturing pattern" and "combining" limitations of claim 1. Id. at *10-12, *15-18. The Board did not evaluate unpatentability of claims 5-7 and 10 because it was "unable to conclude what structure is encompassed" by the "means for detecting" limitation. Id. at *19.

As for the grounds based on Chen with GSM references, the Board found that Cross-Appellants' many offered reasons to combine the references "[did] not suffice as an articulated reason with a rational underpinning to combine the respective teachings of the references." Id. at *24-27. The Board also found that many of Cross-Appellants' reasons to combine Chen and the GSM references lacked clarity. Id. at *25-27. And as with its analysis based on Chen alone, the Board again did not reach claims 5-8 and 10 because it was unable to conclude what structure is encompassed by the "means for detecting" limitation. Id. at *27.

Thus, the Board ultimately determined claims 1-3 and 9 were unpatentable under § 103 based on Chen,...