Trials@uspto.gov
`571-272-7822
`
`Paper: 14
`Entered: August 8, 2017
`
`
`
`
`
`UNITED STATES PATENT AND TRADEMARK OFFICE
`____________
`
`BEFORE THE PATENT TRIAL AND APPEAL BOARD
`____________
`
`APPLE INC.,
`Petitioner,
`
`v.
`
`CALIFORNIA INSTITUTE OF TECHNOLOGY,
`Patent Owner.
`____________
`
`Case IPR2017-00701
`Patent 7,421,032 B2
`____________
`
`
`
`Before KEN B. BARRETT, TREVOR M. JEFFERSON, and
`JOHN A. HUDALLA, Administrative Patent Judges.
`
`BARRETT, Administrative Patent Judge.
`
`
`
`
`DECISION
`Institution of Inter Partes Review
`37 C.F.R. § 42.108
`
`
`571-272-7822
`
`Paper: 14
`Entered: August 8, 2017
`
`
`
`
`
`UNITED STATES PATENT AND TRADEMARK OFFICE
`____________
`
`BEFORE THE PATENT TRIAL AND APPEAL BOARD
`____________
`
`APPLE INC.,
`Petitioner,
`
`v.
`
`CALIFORNIA INSTITUTE OF TECHNOLOGY,
`Patent Owner.
`____________
`
`Case IPR2017-00701
`Patent 7,421,032 B2
`____________
`
`
`
`Before KEN B. BARRETT, TREVOR M. JEFFERSON, and
`JOHN A. HUDALLA, Administrative Patent Judges.
`
`BARRETT, Administrative Patent Judge.
`
`
`
`
`DECISION
`Institution of Inter Partes Review
`37 C.F.R. § 42.108
`
`
`
`IPR2017-00701
`Patent 7,421,032 B2
`
`
`INTRODUCTION
`I.
`A. Background and Summary
`Apple Inc. (“Petitioner”) filed a Petition requesting inter partes
`
`review of U.S. Patent No. 7,421,032 B2, issued September 2, 2008
`(“the ’032 patent,” Ex. 1101). Paper 3 (“Pet.”). The Petition challenges the
`patentability of claims 1–10 of the ’032 patent on the ground of obviousness
`under 35 U.S.C. § 103. California Institute of Technology (“Patent Owner”)
`filed a Preliminary Response to the Petition. Paper 13 (“Prelim. Resp.”).
`An inter partes review may not be instituted “unless . . . the
`
`information presented in the petition . . . shows that there is a reasonable
`likelihood that the petitioner would prevail with respect to at least 1 of the
`claims challenged in the petition.” 35 U.S.C. § 314(a). Having considered
`the arguments and evidence presented by Petitioner and Patent Owner, we
`determine that Petitioner has demonstrated a reasonable likelihood that it
`would prevail in establishing the unpatentability of challenged claims 1 and
`4–10 of the ’032 patent, and that Petitioner has not demonstrated a
`reasonable likelihood that it would prevail in establishing the unpatentability
`of claims 2 and 3 of the ’032 patent.
`
`B. Related Proceedings
`One or both parties identify, as matters involving or related to the
`
`’032 patent, Cal. Inst. of Tech. v. Broadcom Ltd., No. 2:16-cv-03714 (C.D.
`Cal. filed May 26, 2016) and Cal. Inst. of Tech. v. Hughes Commc’ns, Inc.,
`2:13-cv-07245 (C.D. Cal. filed Oct. 1, 2013), and Patent Trial and Appeal
`Board cases IPR2015-00059, IPR2015-00060, IPR2015-00061, IPR 2015-
`00067, IPR2015-00068, IPR2015-00081, IPR2017-00210, IPR2017-00211,
`
`2
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`Patent 7,421,032 B2
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`IPR2017-00219, IPR2017-00297, IPR2017-00423, IPR2017-00700, and
`IPR2017-00728. Pet. 3, Paper 7.
`
`C. The ’032 Patent
`The ’032 patent is titled “Serial Concatenation of Interleaved
`
`Convolutional Codes Forming Turbo-Like Codes.” The ’032 patent
`explains some of the prior art with reference to its Figure 1, reproduced
`below.
`
`
`Figure 1 is a schematic diagram of a prior “turbo code” system. Ex. 1101,
`2:16–17. The ’032 patent specification describes Figure 1 as follows:
`A block of k information bits is input directly to a first coder 102.
`A k bit interleaver 106 also receives the k bits and interleaves
`them prior to applying them to a second coder 104. The second
`coder produces an output that has more bits than its input, that is,
`it is a coder with rate that is less than 1. The coders 102, 104 are
`typically recursive convolutional coders.
`
`Three different items are sent over the channel 150: the
`original k bits, first encoded bits 110, and second encoded bits
`112. At the decoding end, two decoders are used: a first
`constituent decoder 160 and a second constituent decoder 162.
`Each receives both the original k bits, and one of the encoded
`portions 110, 112. Each decoder sends likelihood estimates of
`the decoded bits to the other decoders. The estimates are used to
`decode the uncoded information bits as corrupted by the noisy
`channel.
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`3
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`IPR2017-00701
`Patent 7,421,032 B2
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`Id. at 1:41–56.
`
`A coder 200, according to a first embodiment of the invention, is
`described with respect to Figure 2, reproduced below.
`
`
`Figure 2 of the ’032 patent is a schematic diagram of coder 200.
`
`The coder 200 may include an outer coder 202, an
`interleaver 204, and inner coder 206. . . . The outer coder 202
`receives the uncoded data. The data may be partitioned into
`blocks of fixed size, say k bits. The outer coder may be an (n,k)
`binary linear block coder, where n>k. The coder accepts as input
`a block u of k data bits and produces an output block v of n data
`bits. The mathematical relationship between u and v is v=T0u,
`where T0 is an n×k matrix, and the rate[1] of the coder is k/n.
`
`The rate of the coder may be irregular, that is, the value of
`T0 is not constant, and may differ for sub-blocks of bits in the
`data block. In an embodiment, the outer coder 202 is a repeater
`that repeats the k bits in a block a number of times q to produce
`a block with n bits, where n=qk. Since the repeater has an
`irregular output, different bits in the block may be repeated a
`different number of times. For example, a fraction of the bits in
`the block may be repeated two times, a fraction of bits may be
`repeated three times, and the remainder of bits may be repeated
`four times. These fractions define a degree sequence, or degree
`profile, of the code.
`
`The inner coder 206 may be a linear rate-1 coder, which
`means that the n-bit output block x can be written as x=TIw,
`where TI is a nonsingular n×n matrix. The inner coder 210 can
`
`1 We understand that the “rate” of an encoder refers to the ratio of the
`number of input bits to the number of resulting encoded output bits related to
`those input bits.
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`4
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`Patent 7,421,032 B2
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`have a rate that is close to 1, e.g., within 50%, more preferably
`10% and perhaps even more preferably within 1 % of 1.
`Id. at 2:36–60. In an embodiment, the second (“inner”) encoder 206 is an
`accumulator. Id. at 2:66–67. “The serial concatenation of the interleaved
`irregular repeat code and the accumulate code produces an irregular repeat
`and accumulate (IRA) code.” Id. at 3:30–32.
`
`Figure 4 of the ’032 patent is reproduced below.
`
`
`Figure 4 shows an alternative embodiment in which the outer encoder is a
`low-density generator matrix (LDGM). Id. at 3:56–59. LDGM codes have a
`“sparse” generator matrix. Id. at 3:59–60. The IRA code produced is a
`serial concatenation of the LDGM code and the accumulator code. Id.
`at 3:60–62. No interleaver (as in the Figure 2 embodiment) is required in the
`Figure 4 arrangement because the LDGM provides scrambling otherwise
`provided by the interleaver in the Figure 2 embodiment. Id. at 3:62–64.
`
`D. Illustrative Claim
`Of the challenged claims of the ’032 patent, claim 1 is the only
`
`independent claim. The remaining challenged claims depend directly or
`indirectly from claim 1. Claim 1, reproduced below as corrected by a
`Certificate of Correction, is illustrative:
`1. A method comprising:
`
`receiving a collection of message bits having a first
`sequence in a source data stream;
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`Patent 7,421,032 B2
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`generating a sequence of parity bits, wherein each parity
`
`bit “xj” in the sequence is in accordance with the formula
`
`where
`“xj-1” is the value of a parity bit “j-1,” and
`
`
`
`
`is the value of a sum of “a” randomly chosen irregular[2] repeats
`of the message bits; and
`
`making
`the sequence of parity bits available for
`transmission in a transmission data stream.
`Ex. 1101, 7:63–8:20; id., Certificate of Correction (dated July 27, 2010;
`replacing the two formulae).
`
`
`Reference
`
`E. Applied References
`Dates
`
`D. J. C. MacKay et al., Comparison of Constructions of
`Irregular Gallager Codes, IEEE TRANSACTIONS ON
`COMMUNICATIONS, Vol. 47, No. 10, pp. 1449–54, October
`1999 (“MacKay”)
`
`Exhibit
`No.
`Ex. 1102
`
`
`2 The Board, in a prior decision regarding the ’032 patent, adopted a
`construction where, “[i]n the context of the ’032 patent specification, . . .
`‘irregular’ refers to the notion that different message bits or groups of
`message bits contribute to different numbers of parity bits.” IPR2015-
`00060, Paper 18, 12 (Decision denying institution); see also Pet. 23–24
`(advocating the adoption of that construction in this case); Prelim. Resp. 6
`(referring to “the “irregularity” claimed (‘irregular repeats of the message
`bits’)”).
`
`6
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`
`Reference
`
`Dates
`
`L. Ping et al., Low Density Parity Check Codes with Semi-
`Random Parity Check Matrix, IEE ELECTRONICS LETTERS,
`Vol. 35, No. 1, pp. 38–39, Jan. 7, 1999 (“Ping”)
`M. Luby et al., Practical Loss-Resilient Codes, PROCEEDINGS
`OF THE TWENTY-NINTH ANNUAL ACM SYMPOSIUM ON THEORY
`OF COMPUTING, May 4–6, 1997, at 150–159 (“Luby97”)
`Dariush Divsalar, et al., Coding Theorems for “Turbo-Like”
`Codes, PROCEEDINGS OF THE THIRTY-SIXTH ANNUAL
`ALLERTON CONFERENCE ON COMMUNICATION, CONTROL, AND
`COMPUTING, Sept. 23–25, 1998, at 201–209 (“Divsalar”)
`
`Exhibit
`No.
`Ex. 1103
`
`Ex. 1108
`
`Ex. 1117
`
`Petitioner also relies on the Declaration of Dr. James A. Davis, dated
`
`January 19, 2017 (Ex. 1104), in support of its arguments.
`
`
`
`F. Asserted Ground of Unpatentability
`Petitioner asserts the following ground of unpatentability:
`References
`Basis
`Claims
`Ping, MacKay, Divsalar, and Luby97
`§ 103(a)
`1–10
`
`II. ANALYSIS
`A. Claim Construction
`In an inter partes review, claim terms in an unexpired patent are given
`their broadest reasonable construction in light of the specification of the
`patent in which they appear. 37 C.F.R. § 42.100(b); see also Cuozzo
`Speed Techs. LLC v. Lee, 136 S. Ct. 2131, 2144–46 (2016). Under the
`broadest reasonable construction standard, claim terms are given their
`ordinary and customary meaning, as would be understood by one of ordinary
`skill in the art in the context of the entire patent disclosure. In re Translogic
`Tech., Inc., 504 F.3d 1249, 1257 (Fed. Cir. 2007).
`
`7
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`Based on the current record, we determine that no terms require
`
`explicit construction at this time. See Vivid Techs., Inc. v. Am. Sci. & Eng’g,
`Inc., 200 F.3d 795, 803 (Fed. Cir. 1999) (“[O]nly those terms need be
`construed that are in controversy, and only to the extent necessary to resolve
`the controversy”).
`
`B. The Alleged Obviousness of
`Claims 1–10 Over Ping, MacKay, Divsalar, and Luby97
`Petitioner alleges that claims 1–10 of the ’032 patent would have been
`
`obvious over Ping, MacKay, Divsalar, and Luby97. Pet. 37–74. Patent
`Owner opposes. Prelim. Resp. 4–24.
`
`Petitioner asserts that Ping discloses much of the subject matter of
`claim 1, but maintains that Ping’s outer coder is regular. See Pet. 38; see
`also id. at 52–53. Petitioner relies on MacKay for the teaching of
`irregularity, id. at 37, relies on Divsalar for the teaching of repetition “if
`Ping alone is not understood to teach, or render obvious, repeating
`information bits,” id. at 42, and relies on Luby97 for the teaching of
`receiving a source data stream, id. at 44.
`1. Ping (Ex. 1103)
`Ping is an article directed to “[a] semi-random approach to low
`
`density parity check [LDPC] code design.” Ex. 1103, 38. In this approach,
`“[a]n LDPC code is defined from a randomly generated parity check matrix
`H.” Id. The size of matrix H is (n–k) × n where k is the information length
`and n is the coded length. Id. A codeword c is decomposed “as c = [p, d]t,
`where p and d contain the parity and information bits, respectively.” Id.
`Parity check matrix H can be decomposed into two parts corresponding to p
`and d as “H = [Hp, Hd].” Id. Hp is defined as follows:
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`Id. Hd is created such that it “has a column weight of t and a row weight of
`kt/(n–k) (the weight of a vector is the number of 1s among its elements),” id.,
`such that
`
`
`
`Ex. 1104 ¶ 67.
`Parity bits “p = {pi} can easily be calculated from a given d = {di}”
`
`using the following expressions:
`
`𝑝𝑝1=�ℎ1𝑗𝑗𝑑𝑑
`𝑗𝑗
`
`𝑑𝑑𝑗𝑗 and 𝑝𝑝𝑖𝑖=𝑝𝑝𝑖𝑖−1+�ℎ𝑖𝑖𝑗𝑗𝑑𝑑
`𝑗𝑗
`
`𝑑𝑑𝑗𝑗 (mod 2)
`
`Ex. 1103, 38 (equation (4)).3
`2. MacKay (Ex. 1102)
`MacKay is a paper related to Gallager codes based on irregular
`
`graphs, which are “low-density parity check codes whose performance is
`closest to the Shannon limit.” Ex. 1102, 1449. According to MacKay,
`
`3 The reference to “mod 2” refers to modulo-2 addition. Modulo-2 addition
`
`corresponds to the exclusive-OR (XOR or ⊕) logical operation, which is
`defined as follows: 0⊕0=0, 0⊕1=1, 1⊕0=1, and 1⊕1=0. See Ex. 1104
`
`¶ 180.
`
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`“[t]he best known binary Gallager codes are irregular codes whose parity
`check matrices have nonuniform weight per column.” Id. A parity check
`matrix that “can be viewed as defining a bipartite graph with ‘bit’ vertices
`corresponding to the columns and ‘check’ vertices corresponding to the
`rows” where “[e]ach nonzero entry in the matrix corresponds to an edge
`connecting a bit to a check.” Id. at 1450. As an example of an irregular
`code in a parity check matrix, MacKay describes a matrix that “has columns
`of weight 9 and of weight 3 [and] all rows hav[ing] weight 7.” Id. at 1451.
`3. Divsalar (Ex. 1117)
`Divsalar teaches “repeat and accumulate” codes, described as “a
`
`simple class of rate 1/q serially concatenated codes where the outer code is a
`q-fold repetition code and the inner code is a rate 1 convolutional code with
`transfer function 1/(1 + D).” Ex. 1104 ¶ 82 (quoting Ex. 1117, 1 (Abstr.)).
`Petitioner relies on Divsalar’s Figure 3, reproduced below.
`
`
`
`Figure 3 of Divsalar describes an encoder for a (qN, N) repeat and
`accumulate code. Ex. 1117, 5. The numbers above the input-output lines
`indicate the length of the corresponding block, and those below the lines
`indicate the weight of the block. Id.
`4. Luby97 (Ex. 1108 )
`Luby97 describes “randomized constructions of linear-time encodable
`
`and decodable codes that can transmit over lossy channels at rates extremely
`close to capacity.” Ex. 1108, 150 (Abstr.). Luby97 describes receiving data
`
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`to be encoded in a stream of data symbols, such as bits, where the “stream of
`data symbols [] is partitioned and transmitted in logical units of blocks.” Id.
`(emphasis added, footnote omitted).
`5. The Alleged Obviousness of Independent Claim 1
`For reasons discussed below, Petitioner has shown a reasonable
`
`likelihood that it would prevail in establishing unpatentability of
`independent claim 1 as obvious over Ping, MacKay, Divsalar, and Luby97.
`
`Petitioner, in articulating its obviousness challenge of claim 1, relies
`on the testimony of Dr. Davis and maps the teachings of the prior art against
`the limitations of the claim. Pet. 45–55.
`
`Petitioner maintains that Ping, either alone or in light of Luby97,
`teaches a method including the step of “receiving a collection of message
`bits having a first sequence in a source data stream.” Id. at 45–47 (citing
`Ex. 1104 ¶¶ 120–125). Specifically, Petitioner cites the information bits in
`Ping denoted by vector d for the “receiving” step. Id. at 46. (citing
`Ex. 1103, 38). Petitioner contends that Ping provides equations from which
`parity bits p can easily be calculated from information bits d, and that one of
`ordinary skill in the art would recognize that “message bits” and
`“information bits” are synonymous. Id. at 46–47. Petitioner points to
`Luby97’s teaching of receiving data streams and asserts, “[e]ven if Ping is
`understood to teach only block encoding, and not encoding bits in [the
`claimed] ‘a source data stream,’ it would have been obvious to adapt Ping’s
`coder to work with incoming data streams.” Id. at 47; see id. at 44.
`Petitioner reasons that it would have been obvious to incorporate the stream
`teaching of Luby97 into Ping because coders that receive streams were
`common, id. at 44, 47, and the resulting incorporation would “make the
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`encoder [of Ping] capable of receiving and processing ‘streams’ as opposed
`to blocks.” Id. at 47; see id. at 44–45.
`
`Petitioner next addresses the “generating” step (Pet. 48–53), which
`provides:
`generating a sequence of parity bits, wherein each parity
`
`bit “xj” in the sequence is in accordance with the formula
`
`where
`“xj-1” is the value of a parity bit “j-1,” and
`
`
`
`
`is the value of a sum of “a” randomly chosen irregular repeats of
`the message bits.
`Ex. 1101, 7:66–8:17.
`
`Petitioner asserts that Ping teaches a two-stage, low-density parity-
`check (LDPC)-accumulate code where the value of one parity bit is used in
`the calculation of the next parity bit. Pet. at 24–25, 49–50. Petitioner points
`to Ping’s Equation (4)
`
`
`as teaching the calculation of a parity bit as the sum of the prior parity bit
`and a summation of message bits. Id. at 49–50. Petitioner argues that Ping
`also teaches the “randomly chosen” aspect of the limitation, asserting:
`
`
`Ping randomly determines which values of ℎ𝑖𝑖𝑗𝑗𝑑𝑑 equal “1”
`and which values of ℎ𝑖𝑖𝑗𝑗𝑑𝑑 equal “0.” Specifically, Ping teaches
`
`generating Hd by partitioning it into “t equal sub-blocks,” as
`shown in Equation (3), reproduced below:
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`As Ping explains, “[i]n each sub-block Hdi, i = 1, 2 … t, we
`randomly create exactly one element 1 per column and kt/(n-k)
`1s per row” (Ex. 1103, p. 38, emphasis added.) The positions of
`the 1s in Hd are used to determine which information bits are
`
`included in each summation ∑ ℎ𝑖𝑖𝑗𝑗𝑑𝑑
`𝑑𝑑𝑗𝑗. By placing the 1s into
`𝑗𝑗
`contributing to each of the summations ∑ ℎ𝑖𝑖𝑗𝑗𝑑𝑑
`𝑑𝑑𝑗𝑗 are randomly
`𝑗𝑗
`
`Hd “randomly,” Ping ensures
`
`that
`
`the
`
`information bits
`
`chosen. (Ex. 1104, ¶137.)
`Pet. 51.
`
`Petitioner further contends that “it would have been obvious to one of
`ordinary skill to implement Ping by repeating every message bit [but] . . . , to
`the extent Ping does not itself teach, or render obvious, repeating every
`message bit, Divsalar does so explicitly.” Id. at 52; see id. at 42. Petitioner
`also argues that the use of a repeater in an outer coder was common in the
`art, that [o]ne of ordinary skill would have been further motivated to
`implement Ping using the repeater of Divsalar because this implementation
`would be both cost-effective and easy to build,” and that the similarities
`between Ping and Divsalar provide additional motivation to combine the
`references teachings. Id. at 42–43.
`
`In addressing the “irregular repeats” aspect of claim 1, Petitioner
`contends that, “[i]n Ping’s Hd matrix, every column corresponds to an
`
`information bit (di) and every row corresponds to a summation (∑ ℎ𝑖𝑖𝑗𝑗𝑑𝑑
`𝑗𝑗
`
`and that one of ordinary skill in the art would have understood that the
`summations are computed as the first stage of computing the parity bits in
`Ping. Id. at 30. According to Petitioner, “Ping’s outer LDPC code is regular
`
`𝑑𝑑𝑗𝑗)”
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`because each column in Ping’s generator matrix Hd contains the same
`number of 1s – exactly ‘t’ 1s,” and notes that “Ping thus states that matrix
`‘Hd has a column weight of t . . . .’” Id. at 39 (quoting Ex. 1103, 38); see id.
`at 52–53. Petitioner cites MacKay for teaching that “[t]he best known
`binary Gallager codes are irregular codes whose parity check matrices have
`nonuniform weight per column.” Id. at 40 (quoting Ex. 1102, 1449)
`(emphasis in original).
`
`Petitioner reasons that, “[b]ecause MacKay teaches that irregular
`codes perform better than regular codes, one of ordinary skill would have
`been motivated to incorporate irregularity into Ping.” Id. at 39. Petitioner
`maintains:
`It would have been straightforward for one of ordinary
`
`skill to change Ping’s generator Hd matrix such that different
`columns had different weights – e.g., setting some columns to
`weight 9 and others to weight 3, as taught by MacKay. (Ex.
`1102, p. 1451.) This would result in some information bits
`contributing to more outer LDPC parity bits than others, making
`Ping’s outer LDPC code irregular. This would have been an easy
`way for one of ordinary skill to incorporate the irregularity
`disclosed by MacKay into Ping. Moreover, MacKay’s teaching
`that the best performing LDPC codes are irregular would have
`made this modification obvious (and desirable). (Ex. 1102, pp.
`1449, 1454, “The excellent performance of irregular Gallager
`codes is the motivation for this paper….”) (Ex. 1104, ¶108.)
`Pet. 40. Petitioner notes that Ping credits a reference written by the author
`of MacKay as having creating “revived interest in the low density parity
`check (LDPC) codes originally introduced in 1962 by Gallager.” Id. at 38
`(quoting Ex. 1103, 38). Thus, argues Petitioner, “it would have been
`obvious to one of ordinary skill to incorporate the non-uniform column
`weight of MacKay into the LDPC-accumulate codes of Ping [and] [t]his
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`would result in some information bits being repeated more than others,
`satisfying the ‘irregular repeats’ requirement of claim 1.” Id. at 53 (citing
`Ex. 1104 ¶ 142).
`
`The last step of claim 1 recites “making the sequence of parity bits
`available for transmission in a transmission data stream.” Ex. 1101, 8:19–
`20. Petitioner asserts that Ping, in discussing the performance of the codes,
`teaches the transmission of parity bits. Pet. 54. Petitioner again points to
`Luby97’s teaching of data streams and argues that one of ordinary skill
`would have understood that bits commonly are transmitted in streams and
`that “[i]t would also have been obvious to one of ordinary skill that an
`encoder receiving bits in a stream would have output bits in a stream, and
`that the corresponding decoder would have received encoded bits in a
`stream.” Id. (citing Ex. 1108, 150; Ex. 1104, ¶ 146).
`
`We now turn to Patent Owner’s arguments. Patent Owner first argues
`that MacKay fails to disclose the irregularity of claim 1, namely irregular
`repeats of the message bits. See Prelim. Resp. 6. Specifically, Patent Owner
`asserts that Petitioner fails to identify any “instance of nonuniform weight
`per column among information bits.” Id. at 6–7. Petitioner’s articulated
`ground, however, is based at least on the application of MacKay’s
`irregularity into Ping’s generator Hd matrix making the outer LDPC code
`irregular. Pet. 39–40 (citing, inter alia, Ex. 1104 ¶¶ 106–108); see also
`Pet. 32 (Petitioner arguing “MacKay’s nonuniform weight per column
`ensures that some information bits contribute to more parity bits than
`others.”). Patent Owner’s argument that MacKay standing alone lacks the
`irregular repetition of claim 1 does not persuade us that Petitioner incorrectly
`asserts that the combination of references would result in that subject matter.
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`IPR2017-00701
`Patent 7,421,032 B2
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`Patent Owner also argues “the petition incorrectly addresses only a
`
`portion of Ping’s parity check matrix Hd, rather than the parity check matrix
`H.” Prelim. Resp. 7. Accordingly, Patent Owner argues “Ping’s parity
`check matrix H already includes nonuniform weight per column—i.e., the
`‘irregularity’ of MacKay.” Id. at 7–8. Based on Patent Owner’s
`interpretation of the structure of parity check matrix H as being [Hp, Hd],
`and Patent Owner’s allegation regarding Hd that “[t]he only value of t
`disclosed by Ping is 4” (Prelim. Resp. 8), Patent Owner contends that matrix
`H has column weights as shown in a diagram from page 9 of the Preliminary
`Response, which is reproduced below.
`
`
`Id. at 9, 13. Patent Owner concludes “Ping discloses a parity check matrix
`with different numbers of ones per column—i.e., different column weights
`[weight 2, weight 1, and weight t = 4].” Id. at 9. Thus, Patent Owner argues
`that there would be no motivation to modify Ping to include “irregularity”
`when Ping already includes the aspects identified in MacKay. Id. at 12–13.
`
`Patent Owner’s argument does not address directly Petitioner’s
`articulation of the ground. Petitioner does not utilize Ping’s entire parity
`check matrix H in its analysis; rather, Petitioner notes that the Hd matrix is
`part of Ping’s “parity check” matrix H. Pet. 41. Petitioner maintains that,
`“[b]ecause Ping’s Equation (4) uses the Hd matrix to produce parity bits
`from information bits, it is a ‘generator matrix.’” Id. (citing Ex. 1103, 38).
`
`16
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`IPR2017-00701
`Patent 7,421,032 B2
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`Petitioner asserts that “Ping’s outer LDPC code is regular because each
`column in Ping’s generator matrix Hd contains the same number of 1s –
`exactly ‘t’ 1s,” and notes that “Ping thus states that matrix ‘Hd has a column
`weight of t . . . .’” Id. at 39 (quoting Ex. 1103, 38). As such, we do not
`agree that matrix Hd from Ping, as cited by Petitioner and as forming the
`basis of the articulated ground, already includes “irregularity” in the manner
`suggested by Patent Owner. We understand Petitioner’s combination as
`relating to the specific application of MacKay’s “non-uniform column
`weight” to Ping’s matrix Hd (see Pet. 40, 53), not a generic application of
`“irregularity” to Ping’s teachings as a whole. Accordingly, Patent Owner’s
`arguments do not undermine Petitioner’s stated motivation to combine
`MacKay with Ping.
`
`Patent Owner additionally argues “nothing in the references teach
`such a specific modification” of only Ping’s “submatrix Hd” and that
`“MacKay says nothing about modifying a specific portion of a parity check
`matrix to provide a subset of columns with nonuniform column weights, let
`alone doing so for a portion specifically corresponding to information bits.”
`Prelim. Resp. 10; see also id. 13–14. Nevertheless, Petitioner shows
`persuasively, on this record, that MacKay “teaches how to make LDPC
`matrices ‘irregular’ with ‘nonuniform weight per column.’” Pet. 40 (quoting
`Ex. 1102, 1449). Petitioner cites a specific example in MacKay where a
`matrix “has columns of weight 9 and of weight 3.” Id. (quoting Ex. 1102,
`1451 and citing Ex. 1104 ¶ 107). In light of this evidence, we agree that an
`ordinarily skilled artisan would have known how to add nonuniform column
`weights from MacKay to the uniform column weights in Ping’s matrix Hd.
`
`17
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`IPR2017-00701
`Patent 7,421,032 B2
`
`Having considered Petitioner’s and Patent Owner’s arguments and
`
`evidence, we determine Petitioner has established sufficiently at this stage
`that Ping, MacKay, Divsalar, and Luby97 teach every limitation of claim 1.
`Petitioner also has provided, on the current record, a sufficient rationale for
`its proposed combination. Thus, for the foregoing reasons, Petitioner
`demonstrates a reasonable likelihood of prevailing in showing that claim 1
`would have been obvious over Ping, MacKay, Divsalar, and Luby97.
`6. The Alleged Obviousness of Dependent Claims 2–10 Over Ping,
`MacKay, Divsalar, and Luby97
`The remaining claims subject to Petitioner’s challenge, claims 2–10,
`
`each depend directly or indirectly from independent claim 1.
`a) Claim 2
`Dependent claim 2 recites that “the sequence of parity bits is
`
`generated is [sic] in accordance with ‘a’ being constant.” Ex. 1101, 8:21–
`22. The “a” of claim 1, from which claim 2 depends, refers to the number of
`randomly chosen irregular repeats of the message bits. See id. at 8:16–17
`(the preceding equation “is the value of a sum of ‘a’ randomly chosen
`irregular repeats of the message bits.”).
`Petitioner cites Ping for teaching that the “Hd matrix has ‘kt/(n-k) 1s
`
`per row.’” Pet. 56 (quoting Ex. 1103, 38). Petitioner argues
`“[c]onsequently, the number of message bits chosen for each summation
`
`∑ ℎ𝑖𝑖𝑗𝑗𝑑𝑑
`𝑗𝑗
`
`𝑑𝑑𝑗𝑗 (i.e., the number of message bits summed to produce each outer
`
`LDPC coder parity bit) is also constant – each of Ping’s outer coder LDPC
`parity bits is a sum of kt/(n-k) message bits.” Id. (citing Ex. 1104 ¶ 149); see
`id. at 58 (“[T]he variable ‘a’, as it appears in the claims, corresponds to the
`
`18
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`IPR2017-00701
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`
`weight of a row in the parity check matrix. Claim 2 deals with constant row
`weight, as taught by Ping.”).
`
`Patent Owner notes that Petitioner’s analysis for independent claim 1
`depends on Ping’s matrix Hd as modified by MacKay’s nonuniform column
`weights. See Prelim. Resp. 17. Patent Owner argues that Petitioner,
`applying an inconsistent and incompatible theory, relies on an unmodified
`version of Ping’s Hd for teaching the “‘a’ being constant” limitation in
`claim 2. Id. at 17–18. Patent Owner provides an example of how a matrix
`having constant row weights (like Hd) would no longer have constant
`weights after modification of the column weights to introduce non-
`uniformity. Id. at 17–18.
`
`We are persuaded by Patent Owner’s arguments. Petitioner’s analysis
`for claim 2 is inconsistent with its analysis for claim 1, which relies on a
`version of Ping’s Hd that has been modified according to the teachings of
`MacKay. See Pet. 39–40. Petitioner has not shown persuasively that this
`modified version of Hd still would have the constant “a” of claim 2. Indeed,
`Petitioner’s analysis for claim 2 makes no mention of MacKay or its
`teachings. Accordingly, Petitioner has not shown a reasonable likelihood
`that it would prevail with respect to claim 2 as obvious over Ping, MacKay,
`Divsalar, and Luby97.
`b) Claim 3
`Claim 3 depends from independent claim 1 and recites “the sequence
`
`of parity bits is generated is [sic] in accordance with “a” varying for
`different parity bits.” Ex. 1101, 8:23–25.
`
`Petitioner relies on MacKay for the teaching of this limitation,
`equating nonuniform row weight with the “‘a’ varying for different parity
`
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`bits” aspect of the claim. Pet. 57–59. Petitioner argues that it would have
`been obvious to modify Ping’s Hd matrix to have MacKay’s teaching of
`nonuniform row weights, and contends that this would have been obvious
`for the same reasons given earlier, in the context of claim 1, as to why one
`would consider MacKay’s teachings of nonuniform column weight when
`modifying Ping’s Hd matrix. Id. at 59. However, Petitioner’s specific
`reasoning for modifying the references is that “one of ordinary skill would
`have been motivated to implement MacKay’s uneven row weight in Ping’s
`matrix to determine whether this improved the code’s bit error rate (BER) as
`MacKay suggests (when reporting on the teachings of Luby et al.).” Id.
`(citing Ex. 1102, 1449; Ex. 1104 ¶ 159); see also Ex. 1104 ¶ 159
`(Petitioner’s expert making the same or similar statement).
`
`Patent Owner persuasively argues that Petitioner has failed to
`establish a reason as to why one would have modified Ping as proposed.
`Prelim. Resp. 21–22. Patent Owner quotes a portion of the cited page of
`MacKay that does not suggest what Petitioner proposed but rather implies
`the opposite. Id. at 21. That portion of MacKay, as quoted in the
`Preliminary Response, is as follows:
`The irregular codes of [Luby et al.] have parity check matrices
`with nonuniform weights per row and nonuniform weights per
`column. It has not yet been established whether both of these
`nonuniformities are desirable. In our experience with codes for
`noisy channels, performance is more sensitive to the distribution
`of column weights. In this paper, we concentrate on irregular
`codes with the weight per row as uniform as possible.
`Prelim. Resp. 21 (quoting Ex. 1102, 1449). Without more explanation from
`Petitioner, we are not persuaded that the cited page of MacKay would have
`
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`IPR2017-00701
`Patent 7,421,032 B2
`
`suggested to one of ordinary skill in the art the proposed modification of
`Ping’s Hd matrix to have nonuniform row weights.
`
`Petitioner has not demonstrated a reasonable likelihood of prevailing
`in showing that claim 3 would have been obvious over Ping, MacKay,
`Divsalar, and Luby97.
`
`c) Claims 5 and 6
`Claim 5 depends directly from independent claim 1 and recites
`
`additional requirements for the “generating” step. Patent Owner does not
`address separately Petitioner’s explanations and supporting evidence
`regarding claim 5. Based on the record before us, Petitioner has
`demonstrated a reasonable likelihood that it would prevail on its assertion
`that claim 5 would have been unpatentable over Ping, MacKay, Divsalar,
`and Luby97. See Pet. 63–67.
`
`Claim 6 depends from claim 5 and calls for “generating the random
`sequence of bits comprises coding the collection of message bits usi
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