Sisvel International S.a. v. Sierra Wireless, Inc., Telit Cinterion Deutschland Gmbh, F/d/b/a Thales Dis Ais…

United States Court of Appeals
for the Federal Circuit
______________________
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
______________________
Appeals from the United States Patent and Trademark
Office, Patent Trial and Appeal Board in No. IPR2020-
01099.
______________________
Decided: October 6, 2023
______________________
ROBERT J. G AJARSA , Devlin Law Firm LLC, Wilming-
ton, DE, argued for appellant. Also represented by
T IMOTHY D EVLIN, N EIL A. BENCHELL .
K OURTNEY M UELLER MERRILL , Perkins Coie LLP, Den-
ver, CO, argued for all cross-appellants. Cross-appellant
Sierra Wireless, Inc. also represented by AMANDA T ESSAR .
G UY YONAY , Pearl Cohen Zedek Latzer Baratz LLP,
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SISVEL INTERNATIONAL S. A. v. SIERRA WIRELESS, INC. 2
New York, NY, for cross-appellant Telit Cinterion Deutsch-
land GmbH. Also represented by K YLE AUTERI, I.
______________________
Before M OORE, 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. Cradle-
point, 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 unpatenta-
bility 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 re-
dundant 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 adapta-
tion” and “incremental redundancy,” which it asserts im-
proves prior channel coding techniques. Id. col. 3 ll. 2–5,
col. 4 ll. 19–30. Link adaptation occurs on the
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SISVEL INTERNATIONAL S. A. v. SIERRA WIRELESS, INC. 3
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 retrans-
mission of the data block. See id. col. 2 ll. 25–29. After re-
ceiving 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 punc-
turing 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
1 The code rate refers to “the ratio of the number of
user data bits to the coded data bits of a channel.” Id. col. 1
ll. 50–51. As an example, if 100 data bits are converted into
200 coded data bits to be transmitted over the channel, the
code rate is 100/200 = 1/ 2. Id. col. 1 ll. 51–55.
2 The ’561 patent appears to refer to the terms “bits”
and “symbols” interchangeably. ’561 patent col. 8 ll. 10–13
(“[T]he second puncturing pattern 406 comprises bits
100100100, i.e. only the first and the third symbol thereaf-
ter are retained, while other symbols are removed.”).
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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 origi-
nal 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 com-
prising:
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 in-
cluding 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
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SISVEL INTERNATIONAL S. A. v. SIERRA WIRELESS, INC. 5
coded data block punctured by the second punctur-
ing 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” limita-
tion3:
5. A radio system comprising:
a transmitter and a receiver having a radio connec-
tion 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 punctur-
ing the coded data block by using a first puncturing
pattern, and transmission means for transmitting
the coded data block punctured by the first punc-
turing pattern to the receiver; and
the receiver comprising a channel decoder for de-
coding the received coded data block, means for de-
tecting a need for retransmission of the received
coded data block, and means for transmitting a re-
transmission 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
3 Claim 10 recites the identical limitation “means for
detecting a need for retransmission of the received coded
data block.” We treat claim 5 as representative.
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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 re-
ceived 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 un-
der 35 U.S.C. § 103 over Chen,4 as well as claims 1–10 as
unpatentable under § 103 over Chen and Eriksson5 or
4 World Intellectual Property Organization
(“WIPO”) Patent Application No. PCT/US98/24155, filed
Nov. 12, 1998, Publication No. WO 99/26371, published
May 27, 1999, to Tao Chen et al.
5 S. Eriksson et al., “Comparison of Link Quality
Control Strategies for Packet Data Services in EDGE,”
1999 IEEE 49th Vehicular Technology Conference,
May 16–20, 1999.
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SISVEL INTERNATIONAL S. A. v. SIERRA WIRELESS, INC. 7
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” limita-
tion, the Board construed it as a means-plus-function limi-
tation but determined there was “insufficient algorithmic
structure identified” by Cross-Appellants in its petition.
Id. at *5–6. The Board acknowledged Cross-Appellants’ as-
sertion that the “means for detecting” corresponded to var-
ious protocols mentioned by name in the ’561 patent, such
as forward error correction (FEC), Automatic Repeat Re-
quest (ARQ), and hybrid ARQ, and also acknowledged the
related testimony from Cross-Appellants’ expert, Dr. Ka-
kaes. 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 pro-
gram a processor or hardware to achieve the claimed func-
tion 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 struc-
ture 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
6 Special Mobile Group (“SMG”) of the European Tel-
ecommunications Standards Institute (“ETSI”), Global
System for Mobile Communications (GSM) Technical Spec-
ification (TS) 101 350 V8.0.0 (1999-07), “Digital cellular tel-
ecommunications system (Phase 2+); General Packet Radio
Service (GPRS); Overall description of the GPRS radio in-
terface; Stage 2,” GSM 03.64, Version 8.0.0, Release 1999.
7 We collectively refer to Eriksson and GSM 03.64 as
the “GSM references.”
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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 obvi-
ous 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 refer-
ences, the Board found that Cross-Appellants’ many of-
fered reasons to combine the references “[did] not suffice as
an articulated reason with a rational underpinning to com-
bine 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 en-
compassed 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, but up-
held claims 4–8 and 10. Id.
Sisvel and Cross-Appellants each timely appealed the
Board’s final written decision. We have jurisdiction under
28 U.S.C. § 1295(a)(4)(A) and 35 U.S.C. § 141(c).
S TANDARD OF REVIEW
We review decisions by the Board under the standards
set forth in the Administrative Procedure Act (APA).
5 U.S.C. § 706; Pride Mobility Prods. Corp. v. Permobil,
Inc., 818 F.3d 1307, 1313 (Fed. Cir. 2016). We set aside the
Board’s actions if they are “arbitrary, capricious, an abuse
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of discretion, or otherwise not in accordance with law” or
“unsupported by substantial evidence.” 5 U.S.C.
§ 706(2)(A), (E). The Board’s “[d]eterminations about gov-
erning legal standards and about intrinsic evidence are re-
viewed de novo, and any factual findings about extrinsic
evidence relevant to the question, such as evidence about
knowledge of those skilled in the art, are reviewed for” sub-
stantial evidence. BASF Corp. v. Johnson Matthey Inc.,
875 F.3d 1360, 1365 (Fed. Cir. 2017); ACCO Brands Corp.
v. Fellowes, Inc., 813 F.3d 1361, 1365 (Fed. Cir. 2016).
Obviousness is a question of law based on underlying
findings of fact. In re Gartside, 203 F.3d 1305, 1316 (Fed.
Cir. 2000). Relevant underlying factual questions here in-
clude the scope and content of the prior art, the differences
between the prior art and the claimed invention, whether
the prior art reference teaches away, and the presence or
absence of a motivation to combine. Ariosa Diagnostics v.
Verinata Health, Inc., 805 F.3d 1359, 1364 (Fed. Cir. 2015);
Gen. Elec. Co. v. Raytheon Techs. Corp., 983 F.3d 1334,
1345 (Fed. Cir. 2020).8
D ISCUSSION
I. Appeal
On appeal, Sisvel argues that (1) Chen fails to disclose
a second puncturing pattern, Appellant’s Opening
Br. 12–15; and (2) the Board did not provide a sufficiently
detailed explanation to support its finding that Chen dis-
closes the “combining” limitation, and ignored its rebuttal
arguments, Appellant’s Opening Br. 16–19. We disagree
with Sisvel on both counts.
8 The Board applied pre-AIA law, which the parties
do not dispute. Decision, 2021 WL 6655659, at *3 n.1. We
therefore discuss the pre-AIA versions of all relevant pa-
tentability statutes.
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A. Second Puncturing Pattern
Substantial evidence supports the Board’s finding that
Chen discloses the claimed “second puncturing pattern.”
Decision, 2021 WL 6655659, at *10–12, *15. Claim 1 re-
quires a “first puncturing pattern” and a “second punctur-
ing pattern.” ’561 patent at claim 1. To teach the first and
second puncturing pattern, the Board relied on Chen’s em-
bodiment that has an “original transmission” and a “re-
transmission.” J.A. 1214 ll. 38–39, 1215 ll. 4–37. To create
the original transmission and the retransmission, Chen
discloses a convolutional encoder with, for example, four
generators (g0, g1, g2, and g3) that each output code sym-
bols. J.A. 1214 l. 38–1215 l. 37. For the original transmis-
sion, only the code symbols from generators g0 and g1 are
sent. J.A. 1215 ll. 4–33. When an error occurs in receiving
the originally transmitted packet, a “retransmitted packet”
can be sent that includes “code symbols from other genera-
tors which have not been transmitted previously,” such as
code symbols from generators g2 and/or g3. J.A. 1215 ll. 6–
8. Chen expressly describes that its coded transmissions
are “generated by using punctured codes” and that “[p]unc-
turing reduces the number of code symbols to be retrans-
mitted.” J.A. 1215 ll. 25–37. Cross-Appellants’ expert, Dr.
Kakaes, explained that a skilled artisan would have under-
stood Chen’s selective transmission of selected code sym-
bols from certain generators to refer to puncturing, such
that the original transmission with only code symbols from
generators g0 and g1 correspond to a “first puncturing pat-
tern” and the retransmitted packet with additional code
symbols (e.g., g2) corresponds to a “second puncturing pat-
tern.” J.A. 2481–88 ¶¶ 31–41. Despite Sisvel’s arguments
to the contrary, Appellant’s Opening Br. 13–15, Chen’s dis-
closure and Dr. Kakaes’s testimony are substantial
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evidence supporting the Board’s finding that Chen teaches
the “second puncturing pattern” limitation.9
Sisvel also contends that Chen teaches away from us-
ing a second puncturing pattern. Appellant’s Opening
Br. 15; Appellant’s Reply Br. 4–7. Substantial evidence
supports the Board’s finding that Chen teaches a second
puncturing pattern. Although Chen states that puncturing
“reduces the error correcting capability of the convolutional
code,” J.A. 1215 ll. 35–37, Chen expressly states that “other
code rates can also be generated using punctured codes and
are within the scope of the present invention.” J.A. 1215
ll. 25–26. The latter statement refutes any suggestion of
teaching away, as it expressly contemplates “using punc-
tured codes.” See DePuy Spine, Inc. v. Medtronic Sofamor
Danek, Inc., 567 F.3d 1314, 1327 (Fed. Cir. 2009) (“A refer-
ence may be said to teach away when a person of ordinary
skill, upon reading the reference, would be discouraged
from following the path set out in the reference, or would
be led in a direction divergent from the path that was taken
by the applicant.” (citations omitted)).
B. Combining
Turning to the “combining” limitation, the Board’s
analysis is sufficiently detailed and did not ignore Sisvel’s
arguments. The Board found that Chen’s disclosure of “ac-
cumulating the code symbols from the transmitted and re-
transmitted coded data blocks,” also referred to in Chen as
“interleaving,” teaches the “combining” limitation. Deci-
sion, 2021 WL 6655659, at *12. The Board rejected Sisvel’s
9 The Board reasonably found that Chen discloses
the limitation “a second puncturing pattern including
fewer symbols to be transmitted than the first puncturing
pattern” through Chen’s retransmission of only the code
symbols from generator g2. Decision, 2021 WL 6655659,
at *11–12; J.A. 1215 ll. 16–22.
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argument that Chen’s “interleaving” is different than the
’561 patent’s “combining” limitation, finding them to be the
same. Decision, 2021 WL 6655659, at *17 (“Petitioner fur-
ther contends, and we agree, that ‘“combining” in the ’561
patent and “interleaving” in the second embodiment of
Chen are the exact same thing . . . .’”). In fact, the Board
expressly stated that it considered Sisvel’s arguments in
the Patent Owner Response and Sur-Reply and testimony
from Sisvel’s expert Mr. Bates, but it found Sisvel’s argu-
ments “unavailing” because “the record does not support
the finding that ‘combining’ as recited in claim 1 excludes
interleaving as taught by Chen.” Id. at *17. Moreover, the
Board acknowledged Sisvel’s argument that Chen includes
a statement that “retransmitted packets are interleaved
(not combined).” J.A. 483, 571–72 (both quoting J.A. 1215
ll. 9–10). But the Board found this argument unpersuasive
in light of Chen’s other teachings of accumulating and com-
bining packets. Decision, 2021 WL 6655659, at *16–17
(“[A]lthough Chen distinguishes interleaving from combin-
ing in one instance, it also discloses accumulating packets
and combining packets.”).
Sisvel also asserts that it rebutted the Board’s reliance
on Chen’s disclosure of the “accumulation of packet energy”
for the “combining” limitation. Appellant’s Opening
Br. 17–18 (citing J.A. 484). The Board, however, relied on
Chen’s alternative embodiment describing a method of ac-
cumulating code symbols, which is different than accumu-
lating packet energy. Decision, 2021 WL 6655659, at *12,
*17–18 (citing J.A. 1215 ll. 9–13, 17–24, 33–35). The Board
agreed with Cross-Appellants that Chen’s accumulation of
code symbols through “interleaving” is the same as the ’561
patent’s “combining” because “[b]oth involve the same con-
cept: collecting together different coded symbols from the
transmission and retransmission to be decoded together at
a lower code rate.” Id. at *17.
Accordingly, the Board’s analysis of the “combining”
limitation is sufficiently detailed, adequately addresses
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Sisvel’s related arguments, and is supported by substantial
evidence.
II. Cross-Appeal
Cross-Appellants argue that (1) the Board’s finding
that a skilled artisan would not have been motivated to
combine Chen and the GSM references is not supported by
substantial evidence, Cross-Appellants’ Opening
Br. 33–52; and (2) the Board erroneously found insufficient
corresponding structure in the specification for the term
“means for detecting,” Cross-Appellants’ Opening
Br. 52–61. We hold substantial evidence supports 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.
A. Motivation to Combine
The Board found that each of Cross-Appellants’ ten
reasons for combining Chen and GSM “[did] not suffice as
an articulated reason with a rational underpinning to com-
bine the respective teachings of the references.” Decision,
2021 WL 6655659, at *24–27. That finding was more than
reasonable in this case, where Cross-Appellants’ proposed
combinations and rationales were expressed at such a non-
specific, high level of generality, they never made clear to
the Board what portions of the references were being com-
bined and why a skilled artisan would identify those par-
ticular elements for a combination.
We agree with the Board that Cross-Appellants’ first,
second, and third reasons to combine were merely asser-
tions that the references were analogous art, which, with-
out more, is an insufficient articulation for motivation to
combine. Id. at *24; J.A. 250–251. We further agree with
the Board that Cross-Appellants’ remaining rationales
were too conclusory, lacked clarity, or suffered from both
problems. Decision, 2021 WL 6655659, at *24–27; see, e.g.,
id. at *26 (“[T]he record . . . lacks clarity as to how
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Petitioner contends Chen is modified and/or improved by
[the GSM references] or how Chen itself modifies and/or
improves [the GSM references], respectively, despite Peti-
tioner having had the opportunity, post-institution, to ad-
dress this deficiency.”); id. at *27 (“[I]t is not clear that the
second [modulation coding scheme (MCS)] is that of Chen
or [the GSM references].”). For example, the Petition does
not explain what reference is the primary versus secondary
reference, what elements are missing from the primary ref-
erence, what elements should be added from the secondary
reference to reach the claimed invention, or why those par-
ticular elements would be obvious to add. J.A. 252–262.
Moreover, Cross-Appellants are inconsistent as to how
Chen and the GSM references should be combined. In
some instances, Cross-Appellants allege that a skilled arti-
san would improve Chen with the GSM references. See,
e.g., J.A. 252 (“Applying [the GSM references’ teachings] to
Chen would have been applying known techniques to im-
prove the similar incremental redundancy techniques al-
ready taught by Chen in the same manner.”); J.A. 259
(asserting that a skilled artisan would be “applying [the
GSM references] to Chen . . .”). In other instances, Cross-
Appellants allege the converse—that a skilled artisan
would improve the GSM references with Chen. See, e.g.,
J.A. 542–44 (discussing applying Chen to the GSM stand-
ards described in the GSM references); see also Cross-Ap-
pellants’ Opening Br. 50 (“Cross-Appellants’ argument has
always been that a [skilled artisan] would take Chen’s dis-
closed incremental redundancy retransmission method
and apply it to the mandatory GSM protocols and MCSs to
arrive at the claimed invention.”). Under the circum-
stances, we cannot fault the Board for being at a loss in
trying to decipher Cross-Appellants kitchen-sink of unclear
and confusing motivation-to-combine arguments.
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B. Means for Detecting
1. Proceedings Before the Board
The Board found that Cross-Appellants “fail[ed] to
identify sufficient algorithmic structure” in the specifica-
tion corresponding to claim 5’s “means for detecting a need
for retransmission of the received coded data block.” Deci-
sion, 2021 WL 6655659, at *8. Under the familiar analysis
from this Court’s decision in Noah Systems, Inc. v. Intuit
Inc., “our case law regarding special purpose computer-im-
plemented means-plus-functions claims is divided into two
distinct groups: First, cases in which the specification dis-
closes no algorithm; and second, cases in which the specifi-
cation does disclose an algorithm but a [party] contends
that disclosure is inadequate.” 675 F.3d 1302, 1313 (Fed.
Cir. 2012). Where the specification discloses no algorithm,
the knowledge of a skilled artisan is irrelevant. Id. (citing
Aristocrat Techs. Austl. Pty Ltd. v. Int’l Game Tech., 521
F.3d 1328, 1337 (Fed. Cir. 2008)). But where the specifica-
tion discloses some arguable algorithm, even if a party con-
tends that the algorithm is inadequate, the sufficiency of
the purportedly-adequate structure disclosed in the speci-
fication must be evaluated in light of the knowledge pos-
sessed by a skilled artisan. Id. (citing Aristocrat, 521 F.3d
at 1337; and then AllVoice Computing PLC v. Nuance
Commc’ns, Inc., 504 F.3d 1236, 1245 (Fed. Cir. 2007)).
Before the Board, Cross-Appellants relied on certain
software protocols mentioned by name in the specification
as examples of the corresponding structure, such as “ARQ”
(Automatic Repeat Request) and “hybrid FEC/ARQ (For-
ward Error Correction/Automatic Repeat Request” (hybrid
ARQ). ’561 patent FIG. 2, col. 2 ll. 33–37, col. 10 ll. 41–42;
J.A. 84. Cross-Appellants further relied on the agreement
between both parties’ experts that these software protocols
were well-understood and well-known to a person of ordi-
nary skill. See, e.g., Cross-Appellants’ Br. 54 (“These pro-
tocols were not only known in the art, but were included in
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GSM’s mandatory technical specifications.”); J.A. 523 (pa-
tentee’s expert testifying that “a [skilled artisan] would
well understand what Forward Error Correction is and
where it’s conducted and would also understand what ARQ
is.”). Before the Board and before us, Cross-Appellants ar-
gue that these references to the names of software proto-
cols are sufficient to bring the case out of Noah group one
(absolutely no disclosure) and into Noah group two (some
disclosure). Cross-Appellants assert that it is not always
necessary to set forth in the specification the protocol steps
themselves, as long as the protocol name is sufficient to
connote specific structure to a skilled artisan. We agree
with Cross-Appellants that the Board should have evalu-
ated the protocols disclosed in the specification in light of
the knowledge of a skilled artisan and conducted an analy-
sis appropriate to Noah group two.
The Board disregarded the expert testimony offered by
Cross-Appellants because it appeared to classify this case
as falling within the “no algorithm” group of the Noah
framework, where evidence of a skilled artisan’s knowledge
is irrelevant. For example, the Board rejected Dr. Kakaes’s
apparently undisputed testimony that a skilled artisan
would be familiar with “well-known and commonly used er-
ror detection codes” such as CRC, as well as ARQ and hy-
brid 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 re-
transmission of the received coded data block.’” Decision,
2021 WL 6655659, at *7. The Board relied on our cases
stating that “the testimony of one of ordinary skill in the
art cannot supplant the total absence of structure from the
specification” because § 112 requires that “the specification
itself adequately disclose the corresponding structure.” Id.
(quoting Default Proof Credit Card Sys., Inc. v. Home Depot
U.S.A., Inc., 412 F.3d 1291, 1302 (Fed. Cir. 2005); and then
Noah, 675 F.3d at 1312). Thus, the Board asserted that
even if a skilled artisan “would have known of FEC, CRC,
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ARQ, and hybrid ARQ,” the Board refused to consider that
knowledge because the specification itself contained no “al-
gorithm for performing any one or more of these protocols.”
Id. at 7 (citing the portion of Noah discussing the “total ab-
sence of structure from the specification”).
2. Our Precedents on Noah Group One
Patents falling into the first Noah group involve “the
total absence of structure from the specification.” William-
son v. Citrix Online, LLC, 792 F.3d 1339, 1354 (Fed. Cir.
2015) (emphasis added). Where there is no arguable dis-
closure of structure, “the testimony of one of ordinary skill
in the art” “cannot create structure where none otherwise
exists.” Id. (emphasis added); accord Noah, 675 F.3d at
1313 (explaining that group one cases involve “a total omis-
sion of structure” from the specification).
Some Noah group one cases arise when the patentee
concedes that the patent discloses no structure, but at-
tempts to defend its claims by arguing that structure is not
needed. Robert Bosch, LLC v. Snap-On Inc., 769 F.3d 1094,
1101 (Fed. Cir. 2014) (noting that the patentee conceded
there was no structure in the specification but attempted
to defend the claims by arguing the claims were not subject
to § 112, ¶ 6 at all); EON Corp. IP Holdings LLC v. AT & T
Mobility LLC, 785 F.3d 616, 621, 624 (Fed. Cir. 2015) (ex-
plaining that “[t]he parties agree that the [asserted] pa-
tent’s specification discloses no algorithms, so this case
falls in the first category” of Noah, but noting that the pa-
tentee attempted to rely on the “Katz exception”10 to defend
the lack of structure).
10 The Katz exception arises from this Court’s deci-
sion in In re Katz Interactive Call Processing Patent Litiga-
tion, which held that a microprocessor alone, without an
algorithm, was sufficient disclosure for claims whose
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Other cases finding a “total absence” of structure arise
when we determine that a claim has two (or more) func-
tions, but we find that the disclosed structure applies only
to one of the functions. See, e.g., Tomita Techs. USA, LLC
v. Nintendo Co., 594 F. App’x 657, 662 (Fed. Cir. 2014)
(non-precedential) (holding that a claim involved the func-
tions of “offsetting and displaying,” but omitted any struc-
ture for displaying, and thus fell into Noah group one).
Noah itself was such a case. There, we explained that
when there is disclosed structure for “less than all” of the
functions in a claim, “we must analyze the disclosures as
we do when no algorithm is disclosed.” Noah, 675 F.3d at
1318.
A related line of cases arises when a patentee attempts
to “rewrite the patent’s specification” by using an expert to
retroactively import structure that is totally absent from
the patent. Default Proof, 412 F.3d at 1302; accord Noah,
675 F.3d at 1313 (citing Default Proof, 412 F.3d at 1301).
For example, the patentee in Function Media L.L.C. v.
Google, Inc. sought to excuse its lack of “any disclosure of
the structure” by trying to “rely on the knowledge of one
skilled in the art to fill the gaps” in the specification. 708
F.3d 1310, 1319 (Fed. Cir. 2013). The Function Media pa-
tentee asserted that it would be “unnecessary and extrane-
ous” to require a specification to disclose structure that was
within the background knowledge of a skilled artisan,
functions are so fundamentally basic that they can be
“achieved by any general purpose computer without special
programming.” 639 F.3d 1303, 1316 (Fed. Cir. 2011) (find-
ing a general-purpose microprocessor sufficient structure
for otherwise-unspecified functions of “processing,” “receiv-
ing,” and “storing”). But we immediately characterized In
re Katz as a “narrow exception” to the “default rule” that
an algorithm is required. Ergo Licensing, LLC v. Care-
Fusion 303, Inc., 673 F.3d 1361, 1364–65 (Fed. Cir. 2012).
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citing our decision in Typhoon Touch Technologies, Inc. v.
Dell, Inc. for support. Id. at 1318–19 (citing 659 F.3d 1376,
1385 (Fed. Cir. 2011)). We disagreed with the patentee.
We distinguished Typhoon because that case involved ex-
plicit, though brief, disclosures in the specification. Id. at
1319. Unlike Typhoon’s brief-but-adequately-disclosed al-
gorithm, Function Media involved no disclosure whatso-
ever, and thus appropriately fell into Noah’s first group.
Id. at 1318.
Function Media’s holding fits squarely within a long
line of cases recognizing that expert testimony can “shed
light on” the meaning of a specification’s disclosure without
being tantamount to a “rewrite” of the specification, but
only when some actual disclosure exists in the specifica-
tion. Default Proof, 412 F.3d at 1302 (quoting Omega
Eng’g, Inc. v. Raytek Corp., 334 F.3d 1314, 1332 (Fed. Cir.
2003)); Function Media, 708 F.3d at 1318 (quoting Default
Proof, 412 F.3d at 1302).
Finally, we have considered cases that involve specifi-
cation disclosures that are so generic and vague that they
do not qualify as structure as a matter of law. For example,
we rejected a disclosure of a “standard microprocessor”
with “appropriate programming” because such a disclosure
effectively “imposes no limitation whatever, as any general
purpose computer must be programmed.” Aristocrat, 521
F.3d at 1334; accord Function Media, 708 F.3d at 1318
(holding that a specification’s mere disclosure of “a com-
puter program that transmits” is not structure as a matter
of law because it is merely a non-limiting “abstraction that
simply describes the function”). For similar reasons, we
have also rejected the “bare statement” that any “known
techniques or methods can be used” as structure. Biome-
dino, LLC v. Waters Techs. Corp., 490 F.3d 946, 953 (Fed.
Cir. 2007). Noah itself rejected a general reference to “off
the shelf software” as a basis for the patentee to retroac-
tively “fill the gaps in its specification.” Noah, 675 F.3d at
1317. Analogizing to our cases that rejected disclosures of
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“any computer-related device” as insufficient, Noah con-
cluded that an otherwise-unspecified reference to all “off
the shelf software” was too generic, and therefore “does not
disclose an algorithm” as a matter of law. Id. (citing Black-
board, Inc. v. Desire2Learn, Inc., 574 F.3d 1371, 1383 (Fed.
Cir. 2009)).
3. Our Precedents on Noah Group Two
If there is some disclosure of structure in the specifica-
tion for performing the claimed function, the question of
whether the specification discloses sufficient structure
must be viewed in light of the knowledge of a skilled arti-
san. For example, in Atmel Corp. v. Information Storage
Devices, Inc, we considered whether a specification’s refer-
ence to the title of a scientific article could serve as suffi-
cient structure for a means-plus function limitation. 198
F.3d 1374, 1377 (Fed. Cir. 1999) (claiming a “high voltage
generating means disposed on said semiconductor circuit
for generating a high voltage from a lower voltage power
supply” (emphasis added)). We determined that while the
content of referenced scientific article may not be incorpo-
rated by reference—because the article was not itself part
of the specification—we could consider the title of the arti-
cle, which did appear in the specification. Id. at 1382–83.
Our inquiry, then, turned on what a skilled artisan
would understand from the title of the article itself, which
referenced a particular type of integrated circuit (i.e., on-
chip NMOS integrated circuits) and a particular approach
to generating voltage (i.e., voltage multiplication). Id. at
1377. We noted that the patentee’s expert offered undis-
puted testimony that the title of the article alone was suf-
ficient to indicate the precise structure to a skilled artisan.
Id. at 1382 (“Atmel’s expert, Callahan, testified that this
title alone was sufficient to indicate to one skilled in the art
the precise structure of the means recited in the specifica-
tion. The record indicates that that testimony was essen-
tially unrebutted.”). Thus, while we did not reach outside
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of the specification to evaluate portions of the article “that
do[] not appear in the specification,” we also took account
of what “the specification plainly states”—i.e., the title of
the article—and all that it disclosed to a person of ordinary
skill. Id.; accord S3 Inc. v. NVIDIA Corp., 259 F.3d 1364,
1370–71 (Fed. Cir. 2001) (approving structure where the
details of the structure were not described in the specifica-
tion, but it was a “well known electronic structure and per-
forms a common electronic function, and is readily
implemented from the description in the specification”).
We have applied this skilled artisan perspective for
means-plus-function limitations in the context of software.
In AllVoice Computing PLC v. Nuance Communications,
Inc., we held that “[i]n software cases . . . algorithms in the
specification need only disclose adequate defining struc-
ture to render the bounds of the claim understandable to
one of ordinary skill in the art.” 504 F.3d at 1245 (citing
Med. Instrumentation & Diagnostics Corp. v. Elekta AB,
344 F.3d 1205, 1214 (Fed. Cir. 2003)). There, we relied on
a specification’s reference to “the dynamic data exchange
(DDE) protocol in the Windows operating system” as an al-
gorithm. Id. at 1241–42. Though the specification did not
detail what steps corresponded to the Windows version of
the DDE protocol, we determined that “the reference to
DDE in the specification” was sufficient to require consid-
eration of expert testimony. Id. at 1242. Relying on the
patentee’s expert testimony that implementation of the
DDE protocol “would be a trivial matter” for a skilled arti-
san, we found the claims sufficiently definite. Id.
Thus, for a means-plus-function limitation where the
corresponding structure is an algorithm, the specification
need not disclose all the details of the algorithm to satisfy
the definiteness requirement of § 112 ¶ 2 so long as what
is disclosed would be sufficiently definite to a skilled arti-
san. See Finisar Corp. v. DirecTV Group, Inc., 523 F.3d
1323, 1340 (Fed. Cir. 2008) (explaining that a patentee may
disclose algorithmic structure “in any understandable
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terms including as a mathematical formula, in prose . . . or
as a flow chart, or in any other manner that provides suffi-
cient structure” (emphasis added)).
The line demarking Noah group one from group two is
thus clear: while an expert’s testimony may “not create or
infer the structure” that is totally absent from the specifi-
cation, our cases allow “[e]xpert testimony . . . to show
what” the disclosures that actually appear in the specifica-
tion “would convey to one skilled in the art.” Biomedino,
490 F.3d at 952. Cases where structure is “totally absent”
fall in Noah group one, while cases with even “arguably”
adequate disclosure fall into Noah group two. Noah, 675
F.3d at 1318–19; EON Corp., 785 F.3d at 624 (“Where the
specification discloses an algorithm that the accused in-
fringer contends is inadequate, we judge the disclosure’s
sufficiency based on the skilled artisan’s perspective.” (cit-
ing Noah, 675 F.3d at 1313)).
4. Our Precedents Dictate That This is a Noah Group
Two Case, Requiring Consideration of Expert Testimony
With these principles in mind, the question presented
by this case is whether the specification’s explicit reference
to protocol names—which no party disputes refer to proto-
cols known in the art—is sufficient to bring this case into
Noah group two. We hold that it is. As such, the Board
should have considered the knowledge of a skilled artisan
to assess whether the protocol name sufficiently discloses
an understood algorithm corresponding to the means-plus-
function limitation. Contrary to the Board’s view, that re-
mains true even though the steps corresponding to the pro-
tocols are not expressly set out in the specification. Like in
Noah, the Board thus erred when it “classified this case as
a case involving no disclosed algorithm, and, because of
this error, also improperly refused to allow [Cross-Appel-
lants] to present expert testimony regarding the sufficiency
of the purportedly disclosed algorithm.” Noah, 675 F.3d at
1313.
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This case does not resemble our precedents on Noah
group one. This is not a case, akin to Default Proof, where
there is a “total absence” of disclosure in the specification,
with a party relying on an expert to “rewrite” the specifica-
tion to retroactively insert certain protocols into the pa-
tent—the ’561 patent itself identifies by name the relevant
software protocols in the specification. Nor is this a case,
like Biomedino, involving a vague catch-all phrase, like re-
citing all “known techniques” and leaving the reader to
guess which allegedly known techniques are claimed. The
’561 patent gives a concrete answer by disclosing to a
skilled artisan a discrete, limited, and specific set of soft-
ware protocols: FEC, ARQ, and hybrid ARQ.
The ’561 patent’s disclosures resemble our prior prece-
dents which have permitted reliance on expert testimony,
most particularly Atmel and AllVoice. Because the protocol
names are stated within the ’561 patent’s specification, this
case is indistinguishable from Atmel, where the specifica-
tion’s reference to an article title “alone” was sufficient to
permit consideration of expert testimony on its meaning.
Atmel, 198 F.3d at 1382. Here, Cross-Appellants levy an
identical contention: that the reference to the names of spe-
cific protocols would connote a particular set of steps—an
algorithm—to a skilled artisan. Like the name of the arti-
cle in Atmel, the names of the protocols in the ’561 patent
must be considered for all they disclose to a skilled artisan.
Id. And like the reference to the DDE protocol in AllVoice,
504 F.3d at 1242, the ’561 patent’s reference to protocol
names is enough to require the Board to consider the im-
port of those names in light of the knowledge of a skilled
artisan.
Given the protocols identified in the specification, the
Board should have considered expert testimony to “shed
light on” these disclosures. Default Proof, 412 F.3d at 1302.
That does not allow an expert to create new structure or
imply structure from background knowledge—instead, it
only reads the existing disclosures in the specification for
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all they “would convey to one skilled in the art.” Biome-
dino, 490 F.3d at 952.11
As should be clear, we do not reach the merits of the
factual question of whether the protocols identified in the
’561 patent’s specification disclose sufficient structure to
satisfy § 112 ¶ 2. We instead leave that question for the
Board. On remand, the Board must conduct the analysis
appropriate for Noah group two, including whether any of
the protocols are clearly linked or associated with “the
11 We are quick to emphasize that we do not hold ref-
erence to a protocol name will always be sufficient struc-
ture. For example, it would not be enough to merely
reference the name of a protocol that is unknown in the art,
because the name of an unknown protocol, alone, would not
inform a skilled artisan of the relevant steps that allegedly
constitute an algorithm. Moreover, even references to the
name of a known protocol may not always be enough in all
cases. It may be the case that, as a factual matter, a name
is merely a generic umbrella term that encompasses a vast
and inchoate set of methods; or a name may connote a
meaning that is so vague, varied, or ill-understood that a
skilled artisan would not understand any algorithmic
structure from the name of the protocol alone.
At the same time, the mere fact that a protocol (or other
disclosure) is amenable to more than one implementation
does not, by itself, make it insufficient structure. AllVoice,
504 F.3d at 1245 (approving algorithm as sufficient where
there were “several straightforward ways that [it] could be
implemented by one skilled in the art using well-known
features of the Windows operating system”). Some varia-
bility in implementation of the corresponding structure or
algorithm is permissible, so long as a skilled artisan can
identify “adequate defining structure to render the bounds
of the claim understandable.” Id.
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function recited in the claim,”12 and whether they are “ad-
equate structure for performing this function.”13 We ex-
press no view on those foregoing questions.
12 It is not clear from the Board’s decision whether it
ever settled on which of the protocols named in the specifi-
cation (e.g., ARQ, hybrid ARQ, etc.) are “clearly linked” to
the “means for detecting” limitation. While the determina-
tion of “what structure, if any . . . corresponds to the
claimed function” is a “question[] of law, reviewed de novo,”
we think it prudent to allow the Board to address the ques-
tion in the first instance. Egenera, Inc. v. Cisco Sys., Inc.,
972 F.3d 1367, 1373 (Fed. Cir. 2020).
13 At one point in the Board’s analysis, it appeared to
implicitly require the “means for detecting” to include an
additional function: “detecting the need for retransmission
by an error detection code or by the fact that an error cor-
recting code cannot correct errors occurring on the channel
with sufficient certainty.” Decision, 2021 WL 6655659, at
*8 (cleaned up) (emphasis added). This articulation dif-
fered from the Board’s express construction, id. at *5–6,
which included none of the additional language italicized
in the preceding sentence. See Applied Med. Res. Corp. v.
U.S. Surgical Corp., 448 F.3d 1324, 1334 (Fed. Cir. 2006)
(“A court errs when it improperly imports unclaimed func-
tions into a means-plus-function claim limitation.”). If the
Board intended to modify its construction of the function to
include the additional language, the Board must offer a
reasoned analysis that “fully and particularly set[s] out the
bases upon which it” relied, with sufficient specificity to al-
low “effective judicial review.” Provisur Techs., Inc. v. We-
ber, Inc., 50 F.4th 117, 123 (Fed. Cir. 2022). The Board
must also consider whether the specification associates
that additional function with any of the protocols (such as
ARQ). Cf. ’561 patent FIG. 2, col. 10 l. 41 – col. 11 l. 4.
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C. Impossibility
If the Board finds that the specification lacks a suffi-
ciently disclosed algorithm, the Board should state as
much in its decision. It must then proceed to follow the
guidance in our opinion in Intel Corp. v. Qualcomm Inc., 21
F.4th 801 (Fed. Cir. 2021).
Intel held that when faced with a means-plus-function
limitation with possibly insufficient corresponding struc-
ture in the specification, the Board must either (1) deter-
mine whether the claim is indefinite and then whether
such indefiniteness renders it impossible to adjudicate a
prior-art challenge on the merits, or (2) resolve the prior-
art challenge to the patentability of the claims despite the
potential indefiniteness of the means-plus-function term.
Id. at 804, 814. The Board must also “clearly state that the
final written decision does not include a determination of
patentability of any claim that falls within the impossibil-
ity category.” Id. at 813.
Accordingly, we vacate and remand the Board’s deci-
sion as to the “means for detecting” limitation.
CONCLUSION
We have considered the parties’ remaining arguments
and do not find them persuasive. For the foregoing rea-
sons, the Board’s decision is affirmed-in-part, vacated-in-
part, and remanded for further proceedings consistent with
this opinion.
AFFIRMED-IN-PART, VACATED-IN-PART, AND
REMANDED
COSTS
No costs.
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