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IPR2017-01430
`U.S. PATENT 5,978,951
`
`DOCKET NO.: 2211726-00145
`Filed on behalf of Unified Patents Inc.
`By: David L. Cavanaugh, Reg. No. 36,476
`Daniel V. Williams, Reg. No. 45,221
`Wilmer Cutler Pickering Hale and Dorr LLP
`1875 Pennsylvania Ave., NW
`Washington, DC 20006
`Tel: (202) 663-6000
`Email: David.Cavanaugh@wilmerhale.com
`
`Roshan Mansinghani, Reg. No. 62,429
`Jonathan Stroud, Reg. No. 72,518
`Unified Patents Inc.
`1875 Connecticut Ave. NW, Floor 10
`Washington, DC, 20009
`Tel: (202) 805-8931
`Email: Roshan@unifiedpatents.com
`Email: jonathan@unifiedpatents.com
`
`
`
`
`UNITED STATES PATENT AND TRADEMARK OFFICE
`____________________________________________
`BEFORE THE PATENT TRIAL AND APPEAL BOARD
`
`____________________________________________
`UNIFIED PATENTS INC.
`Petitioner
`v.
`PLECTRUM LLC
`Patent Owner
`IPR2017- 01430
`Patent 5,978,951
`
`PETITIONER’S REQUEST FOR REHEARING
`
`
`
`
`

`

`
`I. 
`II. 
`III. 
`
`IV. 
`
`
`
`TABLE OF CONTENTS
`
`IPR2017-01430
`U.S. PATENT 5,978,951
`
`INTRODUCTION ....................................................................................... 1 
`LEGAL STANDARD ................................................................................. 2 
`BASIS FOR REQUESTED RELIEF .......................................................... 3 
`The Board misapprehended the teachings of Cheriton based on
` 
`inaccuracies introduced by the Patent Owner with respect to
`claims 1, 2, and 21 and overlooked supportive evidence. ..................... 3 
`
` 
`
` 
`
` 
`
` 
`
` 
`
`The Board misapprehended and overlooked inaccuracies
`introduced by the Patent Owner with respect to Ross. ......................... 8 
`
`The Board misapprehended and overlooked Petitioner’s
`obviousness position based on Cheriton in view of Kessler with
`respect to claims 3, 5, and 6. ............................................................... 10 
`
`The Board misapprehended and overlooked Petitioner’s
`obviousness position based on Cheriton in view of Kessler and
`Jain with respect to claims 4 and 22-24. ............................................. 10 
`
`The Board misapprehended and overlooked Petitioner’s
`obviousness position based on Cheriton in view of Jain with
`respect to claims 12-14. ....................................................................... 11 
`
`Additional Misapprehensions .............................................................. 11 
`
`CONCLUSION .......................................................................................... 12 
`
`
`
`i
`
`

`

`TABLE OF AUTHORITIES
`
`IPR2017-01430
`U.S. PATENT 5,978,951
`
`Page(s)
`
`
`CASES
`Star Fruits S.N.C. v. United States,
`393 F.3d 1277 (Fed. Cir. 2005) ........................................................................ 2-3
`KSR International Co. v. Teleflex Inc.,
`550 U.S. 398 (2007) .............................................................................................. 4
`Arisdyne Systems, Inc., v. Cavitation Technologies, Inc.,
`Case IPR2015-00977, slip op. at 20
`(P.T.A.B. Aug. 17, 2015) (Paper 16) ......................................................................... 9
`
`REGULATIONS
`37 C.F.R. § 42.71 ................................................................................................... 1, 2
`
`
`
`ii
`
`

`

`I.
`
`INTRODUCTION
`Petitioner respectfully requests a rehearing pursuant to 37 C.F.R. § 42.71(d)
`
`IPR2017-01430
`U.S. PATENT 5,978,951
`
`for claims 1-6, 12-14, and 21-24 of U.S. Patent 5,978,951. As required by 37
`
`C.F.R. § 42.71(d), the present request specifically identifies each of the matters
`
`that Petitioner believes to have been misapprehended or overlooked by the Board’s
`
`decision.
`
`On November 14, 2017, the Board instituted inter partes review of claims 8
`
`and 11 of U.S. Patent No. 5,978,951. The Board, however, denied institution of
`
`inter partes review of multiple grounds that challenged claims 1-6, 12-14, and 21-
`
`24. See Paper 8 (“Decision”). The denial concerned whether a person of ordinary
`
`skill in the art (“POSA”) would have understood that the 4-way set associative
`
`cache of Cheriton (Ex. 1002) used “rows.”
`
`In its decision, the Board misapprehended the teachings of Cheriton (Ex.
`
`1002) based on unsupported and inaccurate statements introduced by the Patent
`
`Owner. Indeed, in the Patent Owner’s Preliminary Response (“POPR”), the Patent
`
`Owner used attorney argument lacking corroborating expert testimony in alleging
`
`that Cheriton’s 4-way set associative cache memory did not use rows. See e.g.,
`
`POPR at 6-9. Moreover, the Patent Owner misled the Board by introducing
`
`another patent, Ross (Ex. 2001), and mischaracterizing the reference in relation to
`
`the 4-way set associative cache memory of Cheriton. Id. at 7.
`
`1
`
`

`

`IPR2017-01430
`U.S. PATENT 5,978,951
`In contrast, the Petition used sworn expert testimony of Dr. Srinivasan
`
`Seshan (Seshan Declaration, (Ex. 1007)) to support that Cheriton’s cache memory
`
`would have been understood by a POSA as having rows. See Pet. at 23; Seshan
`
`Declaration at ¶62 (Ex. 1007). The Petition further confirmed this understanding
`
`of a POSA using Fujishima (Ex. 1019). Pet. at 23.
`
`The evidentiary record in front of the Board is asymmetric. The Petitioner
`
`supplied expert testimony with corroborating evidence against the Patent Owner’s
`
`attorney argument. In relying on the Patent Owner’s attorney argument, the Board
`
`misapprehended the teachings of Cheriton (Ex. 1002) and improperly denied
`
`institution of claims 1-6, 12-14, and 21-24. Petitioner respectfully requests
`
`rehearing for these claims.
`
`II. LEGAL STANDARD
`A party requesting rehearing must show that a decision should be modified
`
`by identifying “all matters the party believes the Board misapprehended or
`
`overlooked, and the place where each matter was previously addressed in a motion,
`
`an opposition, or a reply.” 37 C.F.R. § 42.71(d). The Board reviews requests for
`
`rehearing under an abuse of discretion standard. Id. § 42.71(c). “An abuse of
`
`discretion occurs where the decision is based on an erroneous interpretation of the
`
`law, on factual findings that are not supported by substantial evidence, or
`
`represents an unreasonable judgment in weighing relevant factors.” Star Fruits
`
`2
`
`

`

`IPR2017-01430
`U.S. PATENT 5,978,951
`S.N.C. v. United States, 393 F.3d 1277, 1281 (Fed. Cir. 2005).
`
`As presented below, the legal and factual errors in the Decision constitute an
`
`abuse of discretion which requires rehearing and institution of the challenged
`
`claims.
`
`III. BASIS FOR REQUESTED RELIEF
`
`
`
` The Board misapprehended the teachings of Cheriton based on
`inaccuracies introduced by the Patent Owner with respect to
`claims 1, 2, and 21 and overlooked supportive evidence.
`Independent claims 1, 2, and 21 recite the following with respect to rows of
`
`a cache:
`
` Claim 1: “comparing said coded address to a value associated with a
`
`row within a cache” and “comparing said received destination address
`
`with a cached destination address associated with a first entry in said
`
`row….” ’951 patent at 16:35-40.
`
` Claim 2: “a network element having a cache comprised of plural
`
`rows,” “using said received, encoded address information to identify
`
`one of said cache rows,” and “retrieving first address information
`
`from a first entry of said identified row….” Id. at 16:47-48.
`
` Claim 21: “a cache having plural rows, each of said rows having
`
`plural entries,” in the view of one of skill in the art….” Id. at 18:55-
`
`56.
`
`3
`
`

`

`IPR2017-01430
`U.S. PATENT 5,978,951
`The Board found that there is “no disclosure that the 4-way set associative
`
`cache in Cheriton is organized by rows.”1 Decision at 15. The Board cites to the
`
`following arguments advanced by the Patent Owner regarding Cheriton. It is
`
`respectfully submitted that the Petitioner’s positions were misapprehended and
`
`overlooked based on the inaccurate arguments advanced by the Patent Owner.
`
`First, the Decision cites to the Patent Owner’s argument that “Cheriton does
`
`not once use the words ‘row’ or ‘rows’ to describe the organization of its cache.”
`
`Id. at 14. This argument focuses on whether the term “row” or “rows” is used
`
`verbatim in Cheriton—relevant to inherent anticipation—as opposed to focusing
`
`on what a POSA would have understood by the disclosure of Cheriton. A finding
`
`of obviousness does not require that claim terms be found verbatim in the prior art,
`
`instead asking whether differences between the claimed subject matter and the
`
`prior art would have been obvious to a person having ordinary skill in the art. KSR
`
`Int’l Co. v. Teleflex Inc., 550 U.S. 398, 406 (2007).
`
`The Petition sets forth expert testimony of Dr. Seshan explaining that a
`
`POSA would have understood that Cheriton’s 4-way set associative cache would
`
`organize entries in rows. See Pet. at 23; Seshan Declaration at ¶62 (EX1007). The
`
`
`1 Petitioner respectfully notes that its positions are based on obviousness and not
`
`anticipation. See, e.g., Pet. at 23 and 30-31.
`
`4
`
`

`

`IPR2017-01430
`U.S. PATENT 5,978,951
`Petition corroborated this understanding—i.e., a 4-way set associative cache is
`
`organized by rows—and referred to Fujishima.2 Id. An obviousness analysis
`
`focusing on whether a claim term is used explicitly in the prior art is legally
`
`improper and overlooks what the prior art in general taught or suggested to one of
`
`ordinary skill in the art. Here, the Petition demonstrated that Cheriton’s 4-way set
`
`associative cache would have taught or at minimum suggested organizing the
`
`entries in rows given the knowledge of a POSA at the time, as supported by Dr.
`
`Seshan and through Fujishima. Pet. at 23. The Board’s analysis based on the
`
`presence or absence of the word row is legal error in the context of an obviousness
`
`determination.
`
`Second, the Decision cites to the Patent Owner argument that Cheriton
`
`“does not teach the use of rows of data because data can be stored sequentially in
`
`blocks, instead of rows.” Decision at 14 (emphasis added). The record is devoid
`
`of any evidence, expert or otherwise, to support the proposition that blocks are
`
`alternatives to rows— indeed, the record teaches the opposite. U.S. Patent
`
`
`2 Fujishima was submitted to further illustrate the known concept of set-associative
`
`cache memory being organized in rows. Fujishima at 12:49-54 (Ex. 1019). See also
`
`Id. at 11:47-57 (describing the system of SRAM memory cell array 12 as a 4-way
`
`set associative cache system) (Ex. 1019).
`
`5
`
`

`

`IPR2017-01430
`U.S. PATENT 5,978,951
`6,711,562 to Ross et al. (“Ross”) (Ex. 2001), introduced by Patent Owner in the
`
`POPR and cited in the Decision at 14, was relied on for the suggestion that tree
`
`structures were an alternative to rows. Ross, however, teaches that a block forms a
`
`part of cache row. In particular, Ross discloses that “block size is the size of the
`
`basic memory unit which is transferred between cache and main memory.” The
`
`reference thus discloses that a block is the data contained within a row, not that it
`
`is an alternative to rows. Ross at 2:44-50.
`
`Thus, it appears the Board relied upon a misapprehension concerning Ross
`
`by the Patent Owner, which led to misunderstanding the nature of Cheriton’s
`
`disclosure and the Board’s finding that Cheriton's disclosure was insufficient. This
`
`factual misunderstanding constitutes an abuse of discretion requiring rehearing and
`
`institution of the challenged claims.
`
`Third, the Decision asserts that Fujishima does not disclose that all 4-way
`
`set associative caches use rows. Decision at 14-16. The Petition cites Fujishima
`
`as evidence to show the knowledge of one of ordinary skill in the art and indicates
`
`that Fujishima discloses a 4-way set associative cache configuration that includes
`
`rows. Pet. at 23; Ex. 1019 at 12:49-54. Fujishima further discloses that its cache
`
`is in the form of SRAM—the same type of cache disclosed in Cheriton. Pet. at 23,
`
`30; Ex. 1002 at 9-34-39; Ex. 1019 at 12:49-54.
`
`6
`
`

`

`IPR2017-01430
`U.S. PATENT 5,978,951
`The Decision asserts that “Petitioner’s reference to Fujishima also fails to
`
`demonstrate that it was known to one of skill in the art that caches, such as those in
`
`Cheriton, would have to use rows.” Decision at 15 (emphasis added). It is
`
`respectfully submitted that the Board committed legal error by requiring an explicit
`
`showing that no other type of organizational structure could be used in a 4-way set
`
`associative cache aside from rows. Obviousness is based on what the prior art
`
`would have reasonably taught or suggested to one of ordinary skill in the art. The
`
`Petition sets forth expert testimony indicating that one of ordinary skill in the art
`
`would have understood Cheriton’s 4-way set associative cache to include rows.
`
`Pet. at 23, 30. Fujishima is corroborating evidence of what one of ordinary skill in
`
`the art would have known regarding the use of rows. Id. at 23. It is respectfully
`
`submitted that any lacking explicit disclosure regarding all 4-way set associative
`
`caches in Fujishima does not detract from—and certainly is not dispositive as to—
`
`Cheriton’s teachings and the knowledge of one of ordinary skill in the art. The
`
`Board’s legally erroneous requirement that Fujishima or some other evidence
`
`disclose all 4-way associative caches as having rows constitutes an abuse of
`
`discretion requiring rehearing and institution of the challenged claims.
`
`Further with respect to claim 1, the Board held that there is no factual
`
`support provided for Dr. Seshan’s opinion that the “first entry in said row” would
`
`be the data that is used for comparison in Cheriton. Decision at 16. The Petition
`
`7
`
`

`

`IPR2017-01430
`U.S. PATENT 5,978,951
`indicates that after looking up the row within the cache, Cheriton compares the
`
`received address against the stored tag fields in the sets stored in the indexed row.
`
`Pet at 23; Cheriton at 9:38-42. The tag field 310 is shown in Figure 3 of Cheriton
`
`as the first entry in the row. Cheriton at Fig. 3; see also Pet. at 33 (the “tag field
`
`310 has four subfields: the destination address field 411, the source address field
`
`312.…”). Based upon the proper understanding of Cheriton as having rows, it is
`
`respectfully submitted that the Board will appreciate that Cheriton teaches that the
`
`“first entry in said row” would be the data that is used for comparison, as discussed
`
`in the Petition and supported by the expert declaration. See, e.g., Pet. at 23, 30-31.
`
`
`
`The Board misapprehended and overlooked inaccuracies
`introduced by the Patent Owner with respect to Ross.
`The Board’s Decision includes reference to Ross3 (Ex. 2001), which the
`
`Patent Owner cites for the proposition that “cache memories may be organized by
`
`several methods other than rows and columns, including, for example, by tree
`
`structures.” See POPR at 7. The first portion of Ross cited in the Decision refers
`
`to “B+-Trees” and “T-Trees” and the second portion cited in Ross mentions a
`
`“cache sensitive search tree.” Decision at 14; Ex. 2001 at 4:24-26; 7:24-41. To
`
`the extent that the Board relied on Ross, such reliance is in error because the Patent
`
`
`3 Ross was not submitted by the Petitioner and is neither related to the challenged
`
`patent nor to Cheriton.
`
`8
`
`

`

`IPR2017-01430
`U.S. PATENT 5,978,951
`Owner’s application of Ross is inaccurate and this factual dispute should be
`
`addressed during trial. See Arisdyne Systems, Inc., v. Cavitation Technologies,
`
`Inc., Case IPR2015-00977, slip op. at 20 (P.T.A.B. Aug. 17, 2015) (Paper 16).
`
`Indeed, Ross does not show that a 4-set associative cache may be organized using
`
`tree structures, and the Patent Owner’s assertion that it does is inaccurate.
`
`In contrast, Ross’s disclosure is directed to organizing data to maximize the
`
`use of a cache and not how to organize the cache itself. See Ross, Abstract. Ross
`
`teaches that characteristics of the cache should be used to organize data, and not
`
`how to structure a cache. The references to tree structures in Ross are about
`
`organizing data in main memory that will be put into a cache, and not about
`
`organization of a 4-set associative cache. Further, Ross indicates that “[c]aches
`
`inherently have such conflicting regions because they have finite levels of
`
`associativity, which results in only a limited number of concurrently accessed data
`
`elements being able to be mapped to the same cache line without generating a
`
`conflict.” Ross at 3:1-5 (emphasis added). Ross is referring to a row in a cache
`
`when it refers to a “cache line,” a point the Board overlooked, and one that further
`
`supports Petitioner’s position and highlights the inaccuracies raised by the Patent
`
`Owner. The Board’s reliance on the tree structures of Ross is misplaced because
`
`the Patent Owner mischaracterized the reference.
`
`9
`
`

`

`IPR2017-01430
`U.S. PATENT 5,978,951
` In sum, Dr. Seshan provided expert testimony that the disclosure of
`
`
`
`Cheriton would have been understood as disclosing rows. Corroborative
`
`evidence was provided in the Petition in the form of Fujishima that 4-way set
`
`associative caches are organized into rows. Patent Owner’s evidence, Ross,
`
`discloses that blocks are part of a cache row, not a way to arrange a cache.
`
`Further, the tree structures of Ross are not disclosed as being an alternative to
`
`using rows in a cache.
`
` The Board misapprehended and overlooked Petitioner’s
`obviousness position based on Cheriton in view of Kessler with respect to
`claims 3, 5, and 6.
`The Board found that Petitioner has not demonstrated a reasonable
`
`likelihood of prevailing on claims 3, 5, and 6 being obvious over Cheriton in view
`
`of Kessler due to these claims depending upon independent claim 2. Decision at
`
`17. Because Petitioner believes that it has demonstrated a reasonable likelihood of
`
`prevailing with respect to independent claim 2, a reasonable likelihood exists of
`
`prevailing with respect to depending claims 3, 5, and 6.
`
` The Board misapprehended and overlooked Petitioner’s
`obviousness position based on Cheriton in view of Kessler and Jain with
`respect to claims 4 and 22-24.
`The Board found that Petitioner has not demonstrated a reasonable
`
`likelihood of prevailing on claims 4 and 22-24 being obvious over Cheriton in
`
`view of Kessler and Jain due to claim 4 depending on independent claim 2 and due
`
`10
`
`

`

`IPR2017-01430
`U.S. PATENT 5,978,951
`to claims 22-24 depending on independent claim 21. Decision at 17-18. Because
`
`Petitioner believes that it has demonstrated a reasonable likelihood of prevailing
`
`with respect to independent claims 2 and 21, a reasonable likelihood exists of
`
`prevailing with respect to dependent claims 4 and 22-24.
`
`
`The Board misapprehended and overlooked Petitioner’s
`obviousness position based on Cheriton in view of Jain with respect to
`claims 12-14.
`The Board held that Petitioner has not demonstrated a reasonable likelihood
`
`of prevailing with respect to claims 12-14 being obvious over Cheriton in view of
`
`Jain because the Petition “relies on arguments related to Cheriton’s alleged
`
`teachings of claim limitations as to the use of ‘rows,’ which [the Board] found
`
`insufficient for claims 1, 2, and 21.” Decision at 22-23. Because Petitioner
`
`believes that it has demonstrated a reasonable likelihood of prevailing with respect
`
`to independent claims 1, 2 and 21 for the reasons noted herein, a reasonable
`
`likelihood exists of prevailing with respect to depending claims 12-14.
`
` Additional Misapprehensions
`The Board also appeared to state that Petitioner’s grounds for using Cheriton
`
`and Fujishima required motivation to modify Cheriton. See Decision at 16. The
`
`Petition, however, did not utilize Fujishima to modify Cheriton. Rather, as noted
`
`above, the Petition properly used Fujishima to demonstrate that a POSA would
`
`11
`
`

`

`IPR2017-01430
`U.S. PATENT 5,978,951
`have understood Cheriton’s 4-set associative cache memory as having rows. Pet. at
`
`23.
`
`Moreover, the declaration of Dr. Seshan provided expert testimony that the
`
`disclosure of Cheriton would have been understood as disclosing rows. As is
`
`proper, corroborative evidence was provided in the Petition in the form of
`
`Fujishima that set associative caches are organized into rows. Therefore, the
`
`declaration of Dr. Seshan is not conclusory.
`
`IV. CONCLUSION
`
`Petitioner respectfully requests that the Board grant rehearing and institute
`
`an inter partes review of claims 1-6, 12-14, and 21-24 of the ’915 patent.
`
`
`
`Respectfully Submitted,
`
`/ David L. Cavanaugh /
`
`
`
`David L. Cavanaugh
`Registration No. 36,476
`
`12
`
`

`

`IPR2017-01430
`U.S. PATENT 5,978,951
`CERTIFICATE OF SERVICE
`I hereby certify that on November 28, 2017, I caused a true and correct copy
`
`of the foregoing materials:
`
`• Petitioner’s Request for Rehearing
`
`to be served upon the following by ELECTRONIC MAIL:
`
`Zachariah S. Harrington: zac@ahtlawfirm.com
`Larry D. Thompson, Jr : larry@ahtlawfirm.com
`Matthew J. Antonelli: matt@ahtlawfirm.com
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`/Daniel V. Williams/
`Daniel V. Williams
`Registration No. 45.221
`
`
`
`
`
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`

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