UNITED STATES PATENT AND TRADEMARK OFFICE
`
`____________
`
`BEFORE THE PATENT TRIAL AND APPEAL BOARD
`____________
`
`SPRINT SPECTRUM L.P., CELLCO PARTNERSHIP D/B/A VERIZON WIRELESS,
`AND AT&T MOBILITY LLC
`Petitioners
`
`v.
`
`ADAPTIX, INC.
`Patent Owner
`
`
`Case No. IPR2016-00824
`Patent 8,934,375
`
`
`PETITION FOR INTER PARTES REVIEW
`OF U.S. PATENT NO. 8,934,375
`Claims 2, 4-8, 11, 13-14, 18, 20-24, 27, 29, 30
`
`
`
`

`
`
`
`Petition for Inter Partes Review of
`U.S. Patent No. 8,934,375
`
`TABLE OF CONTENTS
`
`Page
`
`INTRODUCTION ............................................................................................ 1
`I.
`II. GROUNDS FOR STANDING UNDER 37 C.F.R. § 42.104(A) .......................... 2
`III.
`IDENTIFICATION OF CHALLENGE AND RELIEF REQUESTED .......... 2
`IV. OVERVIEW OF THE ’375 PATENT ................................................................ 2
`A. The Alleged Invention of the ’375 Patent ............................................................. 3
`B. Summary of the Prosecution History of the ’375 Patent ..................................... 3
`C. Level of Ordinary Skill in the Art .......................................................................... 4
`D. Claim Construction Under 37 C.F.R. § 42.104(b)(3) .......................................... 4
`PRIOR ART ...................................................................................................... 7
`A. Summary of the Prior Art ....................................................................................... 7
`B. Overview of Ritter ................................................................................................... 7
`C. Overview of Gesbert ............................................................................................... 8
`D. Overview of Thoumy .............................................................................................. 9
`E. Overview of Gitlin ................................................................................................ 10
`VI. SPECIFIC GROUNDS FOR PETITION ....................................................... 10
`A. Ground 1: Ritter in View of Gesbert and Thoumy Renders Claims 2, 8,
`14, 18, 24, and 30 Obvious ................................................................................... 10
`B. Ground 2: Ritter in View of Gesbert, Thoumy, and Gitlin Renders
`Claims 4-7, 11, 13, 20-23, 27, and 29 Obvious .................................................. 33
`C. Ground 3: Thoumy in View of Gesbert and Gitlin Renders Claims 6-8,
`11, 13, 22-24, 27, and 29 Obvious ....................................................................... 42
`D. Ground 4: Thoumy in View of Gesbert and Ritter Renders Claims 2,
`14, 18, and 30 Obvious ......................................................................................... 56
`E. Ground 5: Thoumy in View of Gesbert, Gitlin, and Ritter Renders
`claims 4, 5, 20 and 21 Obvious ............................................................................ 56
`VII. MANDATORY NOTICES UNDER 37 C.F.R. § 42.8(A)(1) ............................. 58
`A. Real Party-In-Interest and Related Matters ......................................................... 58
`
`V.
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`B. Lead and Back-Up Counsel under 37 C.F.R. § 42.8(b)(3) ............................... 60
`VIII. CONCLUSION ................................................................................................ 60
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`Petition for Inter Partes Review of
`U.S. Patent No. 8,934,375
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`Petition for Inter Partes Review of
`U.S. Patent No. 8,934,375
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`TABLE OF AUTHORITIES
`
` Page(s)
`
`Federal Cases
`In re ICON Health & Fitness, Inc.,
`496 F.3d 1374 (Fed. Cir. 2007) ...................................................................... 5, 45
`
`KSR Int’l Co. v. Teleflex Inc.,
`550 U.S. 398 (2007) .....................................................................................passim
`
`Phillips v. AWH Corp.,
`415 F.3d 1303 (Fed. Cir. 2005) ............................................................................ 5
`
`In re Yamamoto,
`740 F.2d 1569 (Fed. Cir. 2004) ............................................................................ 5
`
`Federal Statutes
`
`35 U.S.C. § 102(a) ................................................................................................... 10
`
`35 U.S.C. § 102(b) ..................................................................................................... 7
`
`35 U.S.C. § 102(e) ................................................................................................. 8, 9
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`35 U.S.C. § 103 ........................................................................................................ 10
`
`35 U.S.C. § 112 .......................................................................................................... 4
`
`35 U.S.C. §§ 311-319 ................................................................................................ 1
`
`35 U.S.C. § 315 ........................................................................................................ 59
`
`35 U.S.C. § 325 ........................................................................................................ 59
`
`Regulations
`
`37 C.F.R. § 42.8(A)(1) ............................................................................................. 58
`
`37 C.F.R. § 42.8(b)(1) .............................................................................................. 58
`
`37 C.F.R. § 42.8(b)(2) .............................................................................................. 59
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`Petition for Inter Partes Review of
`U.S. Patent No. 8,934,375
`37 C.F.R. § 42.8(b)(3) .............................................................................................. 60
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`37 C.F.R. § 42.100 ..................................................................................................... 1
`
`37 C.F.R. § 42.100(b) ................................................................................................ 4
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`37 C.F.R. § 42.104(A)................................................................................................ 2
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`37 C.F.R. § 42.104(b)(3) ............................................................................................ 4
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`37 C.F.R. §§ 42.104(b)(4)-(5) .................................................................................. 10
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`Petition for Inter Partes Review of
`U.S. Patent No. 8,934,375
`
`I.
`
`INTRODUCTION
`
`Pursuant to 35 U.S.C. §§ 311-319, and 37 C.F.R. § 42.100, Petitioners Sprint
`
`Spectrum L.P., Cellco Partnership d/b/a Verizon Wireless, and AT&T Mobility LLC
`
`(collectively “Petitioners”) request inter partes review (“IPR”) of claims 2, 4-8, 11, 13-
`
`14, 18, 20-24, 27, and 29-30 (the “challenged claims”) of U.S. Patent No. 8,934,375 (the
`
`“’375 Patent,” attached as Ex. 1101), issued on January 13, 2015.1
`
`The ’375 Patent is currently being asserted against Petitioners in the United States
`
`District Court for the Eastern District of Texas. The ’375 Patent was applied for and
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`issued in seven months during the course of other litigation against Petitioners involving
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`related U.S. Patent Nos. 7,454,212 (“the ’212 Patent” attached as Ex. 1118) and
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`6,947,748 (“the ’748 Patent” attached as Ex. 1117).2 The ’375 Patent relates to a well-
`
`known technique for adaptively allocating wireless frequency channels, called
`
`“subcarriers,” in an orthogonal frequency division multiple access (“OFDMA”) system.
`
`In particular, the ’375 Patent relates to a system and method for allocating subcarriers to
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`remote devices, called “subscriber units,” and dynamically adjusting those allocations
`
`based on changing channel conditions.
`
`As set forth below, the subject matter of the ’375 Patent was well known, and the
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`claimed inventions obvious, to those of ordinary skill in the art. Accordingly, Petitioners
`
`
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`1 Petitioners are filing another petition challenging different claims of the ’375 Patent.
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`2 Final judgments were entered in favor of Verizon and AT&T in those other litigations.
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`Petition for Inter Partes Review of
`U.S. Patent No. 8,934,375
`request inter partes review and subsequent cancellation of the challenged claims.
`
`II. GROUNDS FOR STANDING UNDER 37 C.F.R. § 42.104(A)
`Petitioners certify that the ’375 Patent is available for IPR and that Petitioners are
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`not barred or estopped from requesting IPR of any claim of the ’375 Patent.
`
`III.
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`IDENTIFICATION OF CHALLENGE AND RELIEF REQUESTED
`
`Petitioners request IPR on the following grounds:
`
`Challenged Claims
`2, 8, 14, 18, 24, 30
`4-7, 11, 13, 20-23, 27, 29
`6-8, 11, 13, 22-24, 27, 29
`2, 14, 18, 30
`4, 5, 20, 21
`
`
`Section IV.D identifies how the challenged claims are to be construed. Section VI
`
`Basis
`§ 103(a)
`§ 103(a)
`§ 103(a)
`§ 103(a)
`§ 103(a)
`
`References
`Ritter, Gesbert, & Thoumy
`Ritter, Gesbert, Thoumy, & Gitlin
`Thoumy, Gesbert, & Gitlin
`Thoumy, Gesbert, & Ritter
`Thoumy, Gesbert, Gitlin, & Ritter
`
`identifies (1) the specific statutory grounds on which the challenge to each claim is
`
`based, (2) an explanation of how each challenged claim is unpatentable for each
`
`ground, and (3) the exhibit numbers and relevance of the supporting evidence. The
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`expert declaration of Richard Gitlin, Sc.D. (Ex. 1102), is provided in further
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`support of this Petition. Taken together, this evidence establishes a reasonable
`
`likelihood that Petitioners will prevail as to the challenged claims.
`
`IV. OVERVIEW OF THE ’375 PATENT
`
`The ’375 Patent issued on January 13, 2015, from Application No. 14/294,106,
`
`which was filed seven months earlier on June 2, 2014 with a Track 1 Request. The ’375
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`Petition for Inter Partes Review of
`U.S. Patent No. 8,934,375
`Patent claims priority to, among other applications, Application No. 09/738,086, filed on
`
`December 15, 2000, and issued as the ’748 Patent, and Application No. 11/199,586, filed
`
`on August 8, 2005, and issued as the ’212 Patent. All three patents share a common
`
`specification. According to Patent Office records, the ’375 Patent is assigned to Adaptix,
`
`Inc. (“Adaptix” or “Patent Owner”). Ex. 1102, Gitlin Decl. at ¶¶ 42-44.
`
`The Alleged Invention of the ’375 Patent
`
`A.
`The claims of the ’375 Patent recite a method and apparatus for adaptively
`
`allocating subcarriers in an OFDMA system. Generally speaking, the claims require a
`
`subscriber unit (1) measuring channel information for subcarriers based on pilot symbols
`
`received from a base station; (2) providing feedback information to the base station,
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`including a modulation and coding rate, for clusters of subcarriers based on the
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`measurements; (3) receiving an allocation of OFDMA subcarriers from the base station,
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`including a modulation and coding rate, selected by the base station for use by the
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`subscriber unit; and (4) repeating these steps at a second time to receive a second
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`allocation of OFDMA subcarriers that is different from the first allocation. See, e.g.,
`
`Claim 1; Ex. 1102, Gitlin Decl. at ¶ 43.
`
`Summary of the Prosecution History of the ’375 Patent
`
`B.
`During prosecution, the Patent Owner submitted five Information Disclosure
`
`Statements (including a 48 page Form PTO-1449 upon initial filing), citing over 1,400
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`references, including hundreds of documents from pending litigation involving the
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`Petition for Inter Partes Review of
`U.S. Patent No. 8,934,375
`related ’748 and ’212 Patents. The Examiner noted, “the number of references submitted
`
`is unreasonably large in quantity and without any indication of relevancy. Examiner
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`made only a best effort in considering all of them. Any reference that may have escaped
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`the Examiner’s attention thus is because of this large number of reference[s] and
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`application shares the burden for both, submitting a large quantity of references and
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`failing to indicate the relevant ones.” Ex. 1113, File History of 14/294,106, June 27, 2014
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`Non-Final Rejection at page 2. After multiple clarifying amendments to address
`
`rejections under 35 U.S.C. § 112, the Examiner issued a final notice of allowance. Id. at
`
`December 2, 2014, Notice of Allowance. Ex. 1102, Gitlin Decl. at ¶ 45.
`
`Level of Ordinary Skill in the Art
`
`C.
`A person having ordinary skill in the art in 2000 (when the first application leading
`
`to the ’375 Patent was filed) would have had either a Bachelor’s degree in electrical
`
`engineering or a similar degree, with at least three to four years of experience in wireless
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`communication technology or other communication-related technology, or a Master’s
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`degree in electrical engineering or a similar degree, with at least two years of experience
`
`in wireless communication technology or other communication-related technology. Ex.
`
`1102, Gitlin Decl. at ¶ 25-29.
`
`D. Claim Construction Under 37 C.F.R. § 42.104(b)(3)
`A claim in inter partes review is given the “broadest reasonable construction in
`
`light of the specification in which it appears.” 37 C.F.R. § 42.100(b). The broadest
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`Petition for Inter Partes Review of
`U.S. Patent No. 8,934,375
`reasonable construction is the broadest reasonable interpretation of the claim language.
`
`See In re Yamamoto, 740 F.2d 1569, 1572 (Fed. Cir. 2004). Any claim term that lacks a
`
`definition in the specification is therefore also given a broad interpretation. In re ICON
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`Health & Fitness, Inc., 496 F.3d 1374, 1379 (Fed. Cir. 2007). Further, applying the claim
`
`construction standard of Phillips v. AWH Corp., 415 F.3d 1303 (Fed. Cir. 2005) would
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`not change the analysis or conclusions covered in this petition. The prior art teaches each
`
`claim limitation under any reasonable interpretation of the claim terms, and the analysis is
`
`not dependent on application of the “broadest reasonable interpretation” standard. Ex.
`
`1102, Gitlin Decl. at ¶ 31.
`
`“pilot symbols”
`
`1.
`In other litigation and a PTAB proceeding involving the ’748 Patent “pilot
`
`symbols” was construed to mean “symbols, sequences, or signals known to both the base
`
`station and subscriber.” Ex. 1112, Claim Construction Order, 6:13-cv-438, Dkt. 901
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`(E.D. Tex., Sept. 19, 2-14) at 17; Ex. 1111, IPR2015-00319 Paper 10. Further, the
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`specification of the ’375 Patent discloses that “pilot symbols, often referred to as a
`
`sounding sequence or signal, are known to both the base station and the subscribers.” Ex.
`
`1101, 5:38-40. Accordingly, the broadest reasonable construction of “pilot symbols” is
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`“symbols, sequences, or signals known to both the base station and subscriber.” Ex.
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`1102, Gitlin Decl. at ¶ 32.
`
`2.
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`“cluster”
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`Petition for Inter Partes Review of
`U.S. Patent No. 8,934,375
`The specification of the ’375 Patent defines a “cluster” as “a logical unit that
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`contains at least one physical subcarrier.” Ex. 1101 at 5:20-21. Accordingly, the broadest
`
`reasonable construction of “cluster” is “a logical unit that contains at least one physical
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`subcarrier.” Ex. 1102, Gitlin Decl. at ¶ 33.
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`“diversity cluster”
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`3.
`The specification of the ’375 Patent describes a “diversity cluster” as a cluster
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`“containing multiple subcarriers with at least some of the subcarriers spread far apart over
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`the spectrum.” Ex. 1101 at 14:28-30. Accordingly, the broadest reasonable construction
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`of a diversity cluster is “a cluster containing multiple subcarriers with at least some of the
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`subcarriers spread far apart over the spectrum.” Ex. 1102, Gitlin Decl. at ¶ 34.
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`“coherence cluster”
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`4.
`The specification of the ’375 Patent describes a “coherence cluster” as a cluster
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`“containing multiple subcarriers close to each other.” Ex. 1101 at 14:27-28. Accordingly,
`
`the broadest reasonable construction of a coherence cluster is “a cluster containing
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`multiple subcarriers close to each other.” Ex. 1102, Gitlin Decl. at ¶ 35.
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`“coherence bandwidth”
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`5.
`The specification of the ’375 Patent describes channel “coherence bandwidth” as
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`“the bandwidth within which the channel response remains roughly the same.” Ex. 1101
`
`at 11:55-60. Accordingly, the broadest reasonable construction of “coherence bandwidth”
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`is “the bandwidth within which the channel response remains roughly the same.” Ex.
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`1102, Gitlin Decl. at ¶ 36.
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`Petition for Inter Partes Review of
`U.S. Patent No. 8,934,375
`
`V.
`
`PRIOR ART
`A.
`The subject matter claimed in the ’375 Patent—adaptive allocation of subcarriers
`
`Summary of the Prior Art
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`in an OFDMA system based on channel quality measurements—was well known as of
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`December 15, 2000, the filing date of the ’375 Patent’s priority application. Each of the
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`prior art references relied upon in this petition has an effective filing date earlier than
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`December 15, 2000. Ex. 1102, Gitlin Decl. at ¶ 27.
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`B. Overview of Ritter
`German Patent DE 19800953 C1 to Ritter (Ex. 1103) is entitled “Procedure and
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`Radio Communication System to Allocate the Radio Resources of a Radio Interface”
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`(“Ritter”). Ritter was published on July 29, 1999, and is prior art to the ’375 Patent under
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`35 U.S.C. § 102(b). Ex. 1103, Ritter at 1. Ritter was cited on the face of the ’375 Patent,
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`but was not substantively discussed during prosecution of the application that issued as
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`the ’375 Patent. The English translation of Ritter (Ex. 1104) was substantively considered
`
`during prosecution of the ’212 Patent. See, e.g., Ex. 1108, ’212 Pros. Hist. Ritter was also
`
`substantively considered by the Board in multiple IPR petitions challenging claims of the
`
`related ’748 and ’212 Patents. See Ex. 1109 IPR2014-01525 Institution Decision; Ex.
`
`1110 IPR2014-01524 Institution Decision; Ex. 1111 IPR2015-00319 Institution
`
`Decision; Ex. 1114 IPR2014-01525, Termination; Ex. 1115 IPR2014-01524,
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`Termination; Ex. 1116 IPR2015-00319, Judgment; Ex. 1102, Gitlin Decl. at ¶ 47.
`
`Ritter teaches an OFDMA wireless communication system in which sets of
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`Petition for Inter Partes Review of
`U.S. Patent No. 8,934,375
`OFDMA subcarriers, referred to as “segments,” are allocated between a base station and
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`multiple mobile stations. Ex. 1104, Ritter at 2-3. Each mobile station uses a training
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`sequence to measure the channel quality of segments of the frequency spectrum and
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`transmits feedback information to the base station identifying suitable segments. Using
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`this feedback information, the base station allocates a segment to each mobile station for
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`data transmission. Id. at 4-5. A “segment” in Ritter, like a “cluster” in the ’375 Patent,
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`may comprise a plurality of subcarriers. Id. at 12-13 (disclosing, as an example, segment
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`Sx comprising subcarriers oc00 – oc40); see also Ex. 1102, Gitlin Decl. at ¶ 48.
`
`C. Overview of Gesbert
`U.S. Patent No. 6,760,882 to Gesbert (“Gesbert”) was filed on September 19,
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`2000, and issued on July 6, 2004. Gesbert is prior art to the ‘375 Patent under 35 U.S.C. §
`
`102(e). Ex. 1105. Gesbert was cited on the face of the ’375 Patent, but was not
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`substantively discussed during prosecution. Gesbert generally teaches a wireless
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`communication system in which modulation and coding rates are dynamically selected
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`based on measured channel quality between a base station and subscriber units. Ex. 1105,
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`Gesbert at 3:60-4:6, Fig. 1; Ex. 1102, Gitlin Decl. at ¶ 49. Gesbert expressly teaches that
`
`its concepts can be used in an OFDMA wireless system. Ex. 1105, Gesbert at 3:57-59.
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`To assess channel quality, Gesbert teaches that “training tones” are transmitted on each
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`subcarrier by the base station. Id. at 8:14-19. These training tones are then used by the
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`subscriber units to measure the quality of each channel. Id. at 5:24-54, 7:7-62, 8:13-34,
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`Petition for Inter Partes Review of
`U.S. Patent No. 8,934,375
`Fig. 5. Based on these measurements, feedback information is transmitted from each
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`subscriber unit to the base station. Id. at 9:52-10:8. Within this feedback information, the
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`subscriber unit includes a “mode” that indicates a modulation and coding rate to be used
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`for subsequent communications. Id. at 4:30-32 (“The system also has a feedback
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`mechanism for communicating the subsequent mode from the receive unit to the transmit
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`unit.”) 3, 6:35-39 (explaining that modes “identify the modulation and coding rates which
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`are to be applied to data”) & Table 1; see also Ex. 1102, Gitlin Decl. at ¶ 50.
`
`D. Overview of Thoumy
`U.S. Patent No. 7,039,120 to Thoumy (“Thoumy”) was filed on November 30,
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`1999, and issued on May 2, 2006. Ex. 1107. Thoumy is prior art to the ’375 Patent
`
`under 35 U.S.C. § 102(e) and was not cited on the face of the ’375 Patent. Thoumy
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`discloses a system for dynamic allocation of carrier frequencies in an OFDMA
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`system. Ex. 1107, at 13:10-19. Thoumy discloses a network with multiple peripheral
`
`stations (id. at 15:17-19 (“FIG. 14 is a general view of a network according to the
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`invention including a base station SIB [sic] and several peripheral stations SPi”) &
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`Fig. 14), implementing OFDM (id. at 1:28-41 (“one particular case is Orthogonal
`
`Frequency Division Multiplex, or OFDM.”)). Thoumy discloses continuously
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`monitoring the actual conditions of the channel for transmission, providing feedback
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`to the base station, and adapting the number of carriers and modulation based on those
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`
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`3 Unless otherwise indicated, all emphasis is added.
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`Petition for Inter Partes Review of
`U.S. Patent No. 8,934,375
`measurements. Id. at 13:20-23; see also Ex. 1102, Gitlin Decl. at ¶ ¶51-52.
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`E. Overview of Gitlin
`U.S. Patent No. 6,018,528 to Gitlin (“Gitlin”) was filed on April 28, 1994, and
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`issued on January 25, 2000. Ex. 1106. Gitlin is prior art to the ’375 Patent under at
`
`least 35 U.S.C. § 102(a). Gitlin was cited on the face of the ’375 Patent, but was not
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`substantively discussed during prosecution. Gitlin discloses a system and method for
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`optimizing frequency allocation to multiple subscribers by using contiguous and non-
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`contiguous frequency assignments for multi-tone, i.e., OFDMA, systems. Ex. 1106,
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`Gitlin at 3:1-12, 5:32-6:18, Fig. 6; see also Ex. 1102, Gitlin Decl. at ¶ 53.
`
`VI. SPECIFIC GROUNDS FOR PETITION
`Pursuant to 37 C.F.R. §§ 42.104(b)(4)-(5), as demonstrated below and
`
`confirmed by Dr. Gitlin (Ex. 1102), the challenged claims are obvious under 35
`
`U.S.C. § 103.
`
`A. Ground 1: Ritter in View of Gesbert and Thoumy Renders Claims 2,
`8, 14, 18, 24, and 30 Obvious
`1.
`Claims 2 and 18, which depend from independent claims 1 (method) and 17
`
`Claims 2 and 18
`
`(apparatus), contain nearly identical limitations. Petitioners address these common
`
`limitations of claims 2 and 18 together, with reference to claim 2 (including the
`
`limitations of independent claim 1), in the ground below. Claim 18 additionally
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`requires a processor in the subscriber unit to perform the recited steps. Ritter
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`Petition for Inter Partes Review of
`U.S. Patent No. 8,934,375
`discloses a control means in the mobile station for measuring channel quality,
`
`selecting carriers, and transmitting and receiving information from the base station.
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`Ex. 1104, Ritter at 5 (“Control means in each mobile station to measure the quality
`
`of various segments…[and] transmit appropriate information to the base station”).
`
`Accordingly, Ritter teaches this limitation. Ex. 1102, Gitlin Decl. at ¶ 54.
`
`(a)
`
`[Claim 1] The preamble: A method for a wireless
`system employing orthogonal frequency division
`multiple access (OFDMA)
`Ritter discloses a wireless system employing OFDMA. See Ex. 1104, Ritter
`
`at 4-5; Ex. 1102, Gitlin Decl. at ¶ 56.
`
`(b)
`
`[Claim 1] Limitation (a): measuring, at a first time by
`a subscriber unit, a first channel information for a
`plurality of subcarriers based on a first plurality of
`pilot symbols received from a base station
`
`Ritter teaches that each subscriber unit measures channel quality information for
`
`subcarriers between it and a base station. For example, Ritter discloses that:
`
`“[a]nother advantageous model of the invention to measure the quality of
`segments of the frequency spectrum envisions, that the mobile station
`receives all subcarriers in the time slot allocated to it, checks for each
`subcarrier, whether an amplitude modulation of the data symbols
`transmitted in the time slot is present, and forms an average value from the
`results of the test for all subcarriers belonging to the respective segment.
`The advantage lies in the two-step procedure in which initially the quality
`is determined for the individual subcarriers and then the quality of the
`subcarriers can be ascertained to determine the quality of the segment
`
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`Petition for Inter Partes Review of
`U.S. Patent No. 8,934,375
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`that was examined in particular.”
`Ex. 1104, Ritter at 8-9; see also id. at 12; Ex. 1102, Gitlin Decl. at ¶ 57.
`
`To the extent the Patent Owner argues that Ritter does not explicitly disclose
`
`“measuring . . . based on a first plurality of pilot symbols,” it would have nevertheless
`
`been obvious to measure channel quality using pilot symbols in view of Gesbert. In
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`particular, Gesbert teaches an OFDMA system that performs subcarrier quality
`
`measurements based on training tones (known to both the subscriber and base station)
`
`received from the base station. Ex. 1105, at 8:13-34. Gesbert explains that “FIG. 5
`
`indicates that training is performed on all tones during an OFDM training symbol, it
`
`will be clear to a person skilled in the art that a subset of these tones could be used for
`
`training and the corresponding frequency response could be computed at the receiver by
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`interpolating.” Id. at 7:16-20. Gesbert uses these training tones to measure channel
`
`quality:
`
`“SINR is sampled during training tones T occurring during sampling
`window τ1. The present embodiment uses multiple carrier frequencies fc
`and thus the SINR is sampled and computed by block 102 for data 52
`transmitted at each of the n carrier frequencies fc. By buffering the SINR
`values for all the training tones T during time window τ1 statistics
`computation block 102 constructs the following matrix:
`
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`Petition for Inter Partes Review of
`U.S. Patent No. 8,934,375
`where SINRi,j is the SINR at the i-th carrier frequency fci during training
`phase j. There are thus 1 to n carrier frequencies fc and 1 to w training
`phases.”
`Id. at 8:13-34; id. at 7:57-59 (“quality parameters include signal-to-interference and noise
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`ratio (SINR)”). One of ordinary skill in the art would understand the training tones of
`
`Gesbert to be the claimed “pilot symbols” according to the construction proffered above
`
`at least because the training tones are necessarily known to both the base station and
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`subscriber. See supra IV.D.1. Indeed, the use of training tones was well known by those
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`skilled in the art in 2000.4 Ex. 1102, Gitlin Decl. at ¶ ¶58-60. Like Ritter and the ’375
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`Patent, Gesbert teaches an OFDMA system in which subscriber units (e.g.,
`
`handsets) measure the quality of a wireless channel and provide feedback to the
`
`base station based on those measurements. Compare Ex. 1105, Gesbert at 2:61-65
`
`(“One or more quality parameters are sampled in the data received by the receive
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`unit. Then, a first-order statistical parameter and a second-order statistical
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`parameter of the quality parameter are computed and used for selecting a
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`subsequent mode for encoding the data.”), 4:30-32 (“The system also has a
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`feedback mechanism for communicating the subsequent mode from the receive
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`
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`4 See, e.g., Bahai and Saltzberg, “Multi-Carrier Digital Communications Theory and
`
`Applications of OFDM,” (Kluwer Academic Publishers, 1999), Ex. 1120, at 29
`
`(“Usually OFDM systems provide pilot signals for channel estimation.”).
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`Petition for Inter Partes Review of
`U.S. Patent No. 8,934,375
`unit to the transmit unit.”), with Ex. 1104, Ritter at 12-13 (“According to the
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`device of the invention every mobile station, MS, measures the quality of various
`
`segments of the frequency spectrum, whereby it receives all subcarriers in the
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`time slot assigned to it, checks the quality of each individual subcarrier and then
`
`determines the quality of the subcarriers. Then each mobile station determines at
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`least a suitable segment preferred for its own communication link and transmits
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`appropriate information to the base station, BS.”); see also Ex. 1102, Gitlin Decl.
`
`at ¶ 61.It would have been obvious to use pilot symbols to measure channel quality
`
`in the system of Ritter as taught by Gesbert for at least the following reasons. One
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`rationale to combine is: “application of a known technique to a piece of prior art
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`ready for the improvement” to “yield predictable results.” KSR Int'l Co. v. Teleflex
`
`Inc., 550 U.S. 398, 401 (2007). Base system: Ritter discloses an OFDMA system
`
`that dynamically allocates subcarrier segments (i.e., subcarriers) to a mobile station
`
`(i.e., subscriber unit) based on the quality of the segments. Ex. 1104, at 8-9, 14.
`
`Ritter discloses using pilot symbols. Id. at 16. Known technique: As shown by
`
`Gesbert, using pilot symbols within an OFDMA wireless communication system to
`
`measure channel quality was well known in the art at the time of the alleged
`
`inventions, and was a simple design choice from among many possible
`
`alternatives. Ex. 1105, at 8:13-34. Even the ’375 Patent acknowledges that
`
`measuring channel quality based on pilot symbols was a well-known technique.
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`Petition for Inter Partes Review of
`U.S. Patent No. 8,934,375
`Ex. 1101, at 9:14-17. Predictable results and improved system: One of ordinary
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`skill in the art would have been motivated to modify Ritter to measure channel
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`quality using pilot symbols, as taught by Gesbert, to obtain the predictable and
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`desirable result of an improved channel allocation process. Ex. 1102, Gitlin Decl.
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`at ¶¶ 62-65. Another rationale to combine is where “the substitution of one known
`
`element for another” yields predictable results. See KSR, 550 U.S. at 401. As
`
`discussed above, using pilot symbols to measure channel quality was a well-known
`
`technique in the art at the time of the alleged invention. And both Ritter and
`
`Gesbert disclose allocating channels based on channel quality measurements and
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`using pilot symbols transmitted from the base station (in some form). As such,
`
`those of ordinary skill in the art would recognize that it would be easy to modify
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`Ritter to measure channel quality using pilot symbols, as described in Gesbert.
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`Such a modification would have yielded predictable results without requiring
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`undue experimentation. Therefore, it would have been obvious to modify Ritter’s
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`OFDMA system to perform the channel quality measurements using pilot symbols,
`
`as in Gesbert. Ex. 1102, Gitlin Decl. at ¶ 66. Further, those of ordinary skill in the
`
`art in 2000 would have been motivated to modify Ritter’s communication system
`
`to measure channel quality using pilot symbols, as in Gesbert, based on the similar
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`nature of the problem solved: both references provide solutions for adapting to
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`varying channel conditions in wireless OFDMA systems. Ex. 1104, Ritter at 4, 7-8;
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`Petition for Inter Partes Review of
`U.S. Patent No. 8,934,375
`Ex. 1105, Gesbert at 2:45-48, 11:44-48. Thus, the similar nature of the problem
`
`solved by Ritter and Gesbert, and the similar manner in which they each solve that
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`problem, would have motivated those of ordinary skill in the art to modify Ritter’s
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`OFDMA system to use channel quality measurements based on pilot symbols, as
`
`described in Gesbert, as a substitute for Ritter’s amplitude-based measurements, to
`
`yield predictable results. Moreover, both Ritter and Gesbert are in the same field of
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`endeavor as the ’375 Patent. Accordingly, the combination of Ritter and Gesbert
`
`teaches this limitation. Ex. 1102, Gitlin Decl. at ¶¶ 67-68.
`
`(c)
`
`[Claim 1] Limitation (b): providing, by the subscriber
`unit, a first feedback information relating to a
`plurality of feedback clusters based on at least the
`measuring of the first channel information for the
`plurality of subcarriers based on the first plurality of
`pilot symbols, each feedback cluster of the plurality of
`feedback clusters being at least two subcarriers, the
`first feedback information relating to the pluralit