`
`
`
`UNITED STATES PATENT AND TRADEMARK OFFICE
`
`__________________
`
`BEFORE THE PATENT TRIAL AND APPEAL BOARD
`
`___________________
`
`SIRIUS XM RADIO INC.,
`Petitioner,
`
`v.
`
`FRAUNHOFER-GESELLSCHAFT ZUR
`FÖRDERUNG DER ANGEWANDTEN
`FORSCHUNG E.V.,
`Patent Owner.
`
`____________________
`
`Case No. _____________
`Patent No. 6,993,084
`
`__________________________________________________________
`
`PETITION FOR INTER PARTES
`REVIEW OF U.S. PATENT NO. 6,993,084
`
`
`
`
`
`

`

`Petition for Inter Partes Review
`U.S. Patent No. 6,993,084
`
`
`TABLE OF CONTENTS
`
`Page
`
`INTRODUCTION ........................................................................................... 1 
`I. 
`II.  MANDATORY NOTICES (37 C.F.R. § 42.8) ............................................... 3 
`A. 
`Real Party-in-Interest (37 C.F.R. § 42.8(B)(1)) .................................... 3 
`B. 
`Related Matters (37 C.F.R. § 42.8(B)(2)) ............................................. 4 
`C.  Designation of Lead and Back-Up Counsel (37 C.F.R. §
`42.8(B)(3)) ............................................................................................. 4 
`Service Information (37 C.F.R. § 42.8(B)(4)) ...................................... 5 
`D. 
`III.  PAYMENT OF FEES (37 C.F.R. § 42.103) ................................................... 5 
`IV.  REQUIREMENTS FOR INTER PARTES REVIEW UNDER
`37 C.F.R. §§ 42.104 ......................................................................................... 5 
`A.  Grounds for Standing (37 C.F.R. § 42.104(A)) .................................... 5 
`Identification of Challenged Claims (37 C.F.R. §
`B. 
`42.104(B)(1)) and Relief Requested (37 C.F.R. §
`42.22(A)(1)) .......................................................................................... 6 
`The Prior Art and Specific Grounds on Which the
`Challenge to the Claims is Based (37 C.F.R. §
`42.104(B)(2)) ......................................................................................... 6 
`Claim Construction (37 C.F.R. § 42.104(B)(3)) ................................... 7 
`D. 
`SUMMARY OF THE ‘3084 PATENT AND ITS TECHNICAL
`FIELD .............................................................................................................. 7 
`A.  Overview of the Technical Field ........................................................... 7 
`1.  Modulation .................................................................................. 7 
`2.  Multi-Carrier Modulation (MCM) .............................................. 9 
`3.  MCM Frame Synchronization .................................................. 10 
`The Fourier Transform .............................................................. 13 
`4. 
`B.  Overview of the ‘3084 Patent .............................................................. 14 
`C. 
`Take-Aways From the Prosecution History ........................................ 19 
`
`V. 
`
`C. 
`
`
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`

`

`Petition for Inter Partes Review
`U.S. Patent No. 6,993,084
`
`VI.  PERSON OF ORDINARY SKILL IN THE ART ........................................ 20 
`VII.  GROUNDS FOR UNPATENTABILITY – THERE IS A
`REASONABLE LIKELIHOOD THAT AT LEAST ONE
`CLAIM OF THE ‘3084 PATENT IS UNPATENTABLE ........................... 20 
`A.  Ground 1: Cimini Anticipates Claims 1, 2, 6, 7, 9 and 18 .................. 20 
`1. 
`Cimini Anticipates Independent Claim 1 .................................. 22 
`2. 
`Cimini Anticipates Dependent Claim 2 .................................... 30 
`3. 
`Cimini Anticipates Claim 6 ...................................................... 32 
`4. 
`Cimini Anticipates Claim 7 ...................................................... 38 
`5. 
`Cimini Anticipates Claim 9 ...................................................... 38 
`6. 
`Cimini Anticipates Claim 18 .................................................... 43 
`B.  Ground 2: Cimini in View of ADSL and/or the
`Knowledge of a POSA Render Claims 1, 2, 6, 7, 9 and 18
`Obvious ............................................................................................... 46 
`C.  Ground 3: Cimini in View of Palacherla Render Claims
`11 and 20 Obvious ............................................................................... 50 
`D.  Ground 4: Cimini in View of Schmidl Render Claims 3,
`8, 10, 14, 19 and 23 Obvious ............................................................... 51 
`1. 
`Claims 3 and 8 ........................................................................... 51 
`2. 
`Claims 10 and 19....................................................................... 55 
`3. 
`Claims 14 and 23....................................................................... 58 
`Ground 5: Cimini in View of the Teachings of Spilker
`Render Claims 12, 15 and 21 Obvious ................................................ 60 
`1. 
`Claims 12 and 21....................................................................... 60 
`2. 
`Claim 15 .................................................................................... 63 
`Ground 6: Cimini in View of Spilker and Further in View
`of Turin Render Claim 16 Obvious ..................................................... 64 
`1. 
`Claim 16 .................................................................................... 64 
`G.  Ground 7: Cimini in View of Spilker and Turin and
`Further in view of Schmidl Render Claim 17 Obvious ...................... 68 
`1. 
`Claim 17 .................................................................................... 68 
`VIII.  CONCLUSION .............................................................................................. 70 
`
`E. 
`
`F. 
`
`
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`- ii -
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`

`

`Petition for Inter Partes Review
`U.S. Patent No. 6,993,084
`
`CERTIFICATE OF COMPLIANCE WITH 37 C.F.R. § 42.24 .............................. 71 
`
`
`
`
`
`
`
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`- iii -
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`

`

`Petition for Inter Partes Review
`U.S. Patent No. 6,993,084
`
`
`TABLE OF AUTHORITIES
`
` Page(s)
`
`Cases
`Ericsson Inc. v. Intellectual Ventures I LLC,
`IPR2014-00527, Paper 41 (May 18, 2015) ........................................................... 3
`
`Fraunhofer v. Sirius XM Radio Inc.,
`1:17-cv-00184 (D. Del. Feb. 22, 2017) .......................................................passim
`
`Global Tel*Link Corp. v. Securus Technologies, Inc.,
`IPR2017-01437, Paper No. 7 (PTAB Dec. 4, 2017) .................................... 46, 60
`
`LG Elecs., Inc. v. Advanced Micro Devices, Inc.,
`IPR2015-00329, Paper 13 (July 10, 2015) ........................................................... 3
`
`Statutes
`
`35 U.S.C. § 102 .................................................................................................passim
`
`35 U.S.C. § 103 ...................................................................................................... 1, 3
`
`35 U.S.C. §§ 311–319 ................................................................................................ 1
`
`Other Authorities
`37 C.F.R. § 42 ...................................................................................................passim
`
`
`
`
`
`- iv -
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`

`

`Petition for Inter Partes Review
`U.S. Patent No. 6,993,084
`
`
`PETITIONER’S EXHIBIT LIST
`
`
`EXHIBIT NO.
`
`Exhibit-1001
`
`Exhibit-1002
`
`Exhibit-1003
`
`Exhibit-1004
`
`Exhibit-1005
`
`Exhibit-1006
`
`DESCRIPTION
`
`U.S. Patent No. 6,993,084 (the “’3084 Patent”) titled, Coarse
`Frequency Synchronisation in Multicarrier Systems, issued on
`January 31, 2006
`
`Declaration of David Lyon, Ph.D., in support of Petition for
`Inter Partes Review of U.S. Patent 6,993,084, dated February
`22, 2018 (“Lyon Dec.”)
`
`U.S. Patent No. 5,914,933 (“Cimini”) titled, Clustered OFDM
`Communication System, issued on June 22, 1999
`
`American National Standard for Telecommunications, Network
`and Consumer Installation Interfaces, Asymmetric Digital
`Subscriber Line (ADSL) Metallic Interface, approved for
`publication August 18, 1995 (“ADSL”)
`
`A. Palacherla, DSP-µP Routine Computes Magnitude,
`Electrical Design News, Vol. 34, No. 22, Oct. 26, 1989
`(“Palacherla”)
`
`U.S. Patent No. 5,732,113 (“Schmidl”) titled, Timing and
`Frequency Synchronization of OFDM Signals, issued on March
`24, 1998
`
`Exhibit-1007
`
`Spilker, Digital Communications by Satellite, 1977 (“Spilker”)
`
`Exhibit-1008
`
`G. Turin, Introduction to Spread-Spectrum Antimultipath
`Techniques and Their Application to Urban Digital Radio,
`Proceedings of the IEEE, Vol. 68, No. 3, March 1980 (“Turin”)
`
`Exhibit-1009
`
`RESERVED
`
`Exhibit-1010
`
`Prosecution History of U.S. Patent No. 6,993,084 (excerpts)
`
`Exhibit-1011
`
`U.S. Patent No. 5,353,352 (the “‘352 Patent”) titled, Multiple
`Access Coding for Radio Communications, issued on October
`4, 1994
`
`
`
`- vi -
`
`

`

`EXHIBIT NO.
`
`Exhibit-1012
`
`Exhibit-1021
`
`Exhibit-1022
`
`Petition for Inter Partes Review
`U.S. Patent No. 6,993,084
`
`
`DESCRIPTION
`
`IEEE Xplore web archive denoting, G. Turin, Introduction to
`Spread-Spectrum Antimultipath Techniques and Their
`Application to Urban Digital Radio, Proceedings of the IEEE,
`Vol. 68, No. 3, March 1980 (“Turin”), available at
`http://ieeexplore.ieee.org/document/1455914/
`
`J. G. Proakis, Digital Communications, McGraw Hill, Inc., 2nd
`Ed. 1989, (“Proakis”) (excerpts)
`
`B. P. Lathi, Modern Digital and Analog Communication
`Systems, The Dryden Press, Saunders College Publishing, 2nd
`Ed., 1989 (“Lathi”) (excerpts)
`
`Exhibit-1023 W. Zou and Y. Wu, COFDM: An Overview, IEEE Transactions
`on Broadcasting, Vol. 41, No. 1, March 1995 (“Zou”)
`
`Exhibit-1024 M. Abramowitz and I. A. Stegun, Handbook of Mathematical
`Functions with Formulas, Graphs, and Mathematical Tables,
`Dover Publications, Inc. (1968) (“Abramowitz”)
`
`
`
`
`
`- vii -
`
`

`

`Petition for Inter Partes Review
`U.S. Patent No. 6,993,084
`
`
`Sirius XM Radio Inc. petitions for inter partes review under 35 U.S.C.
`
`
`
`§§ 311–319 and 37 C.F.R. § 42 of claims 1-3, 6-12, 14-21 and 23 of U.S.
`
`6,993,084 (Ex. 1001, the “‘3084 Patent”). Petitioner asserts that there is a
`
`reasonable likelihood that at least one claim is unpatentable and respectfully
`
`requests review of, and judgment against, claims 1-3, 6-12, 14-21 and 23 (the
`
`“Challenged Claims”) as unpatentable under 35 U.S.C. § 102 and § 103.
`
`I.
`
`INTRODUCTION
`
`The ‘3084 Patent is directed to the broadcast transmission and processing of
`
`digital information such as used in known multi-carrier modulation (“MCM”)
`
`radio transmission systems using orthogonal frequency division multiplexing
`
`(“OFDM”). Ex. 1001, 1:5-16. Specifically, with the underlying aim of combating
`
`signal corruption, the ‘3084 Patent claims the use of signals having a frame
`
`structure, which includes a reference symbol. Id., Claims 1, 6, 9, 18; 1:27-2:2.
`
`The reference symbol is transmitted at the beginning of each frame to enable a
`
`receiver to identify the start of the incoming frame—that is, to facilitate frame
`
`synchronization of signals received by the receiver. Id., 2:3-8; FIG. 1. The
`
`particular reference symbol is inserted in the time domain into the signal and has a
`
`real part and an equal imaginary part formed by an amplitude modulated bit
`
`sequence. Id., Claims 1, 6, 9, 18.
`
`
`
`- 1 -
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`

`

`Petition for Inter Partes Review
`U.S. Patent No. 6,993,084
`
`This purported invention was, however, within the knowledge of a person of
`
`ordinary skill in the art (“POSA”) prior to April 14, 1998, the effective filing date.
`
`Expert Declaration of David Lyon, Ph.D. (Ex. 1002, “Lyon”) ¶¶83-97. The
`
`claimed invention was also readily discernible in prior art printed publications not
`
`considered by the USPTO during prosecution—particularly, Cimini, U.S. Patent
`
`5,914,933, “Clustered OFDM Communication System,” which issued on June 22,
`
`1999, based on an application filed on October 15, 1996 (Ex. 1003, “Cimini”).
`
`For many of the Challenged Claims (including all the independent claims),
`
`Cimini teaches all the ‘3084 claim limitations. Furthermore, the combined
`
`teachings of Cimini and the following additional references render obvious the
`
`Challenged Claims: (i) ANSI T1.413-1995, Asymmetric Digital Subscriber Line
`
`(ADSL) Metallic Interface, 18 August 1995 (Ex. 1004, “ADSL”); (ii) Palacherla,
`
`DSP-mP Routine Computes Magnitude, EDN, Oct. 26, 1989 (Ex. 1005,
`
`“Palacherla”)1; (iii) Schmidl U.S. Patent 5,732,113, “Timing and Frequency
`
`
`
`
`1 Palacherla is a prior art printed publication bearing the copyright date of 1989.
`
`EX. 1005 (also showing that it was published in EDN on Oct. 26, 1989). Further,
`
`the ‘3084 Patent cites to Palacherla. ‘3084 Patent at 2 (“OTHER
`
`PUBLICATIONS”).
`
`
`
`- 2 -
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`

`

`Synchronization of OFDM Signals,” which issued March 24, 1998, based on an
`
`Petition for Inter Partes Review
`U.S. Patent No. 6,993,084
`
`
`application filed on June 20, 1996 (Ex. 1006, “Schmidl”); (iv) Spilker, Digital
`
`Communications by Satellite, 1977 (Ex. 1007, “Spilker”) and (v) Turin,
`
`Introduction to Spread-Spectrum Antimultipath Techniques and Their Application
`
`to Urban Digital Radio, 1980 (Ex. 1008, “Turin”)2.
`
`Accordingly, Petitioner respectfully requests that the Board find all the
`
`Challenged Claims unpatentable under 35 U.S.C. § 102 and § 103 in view of the
`
`foregoing prior art references on the Grounds presented below.
`
`II. MANDATORY NOTICES (37 C.F.R. § 42.8)
`A. Real Party-in-Interest (37 C.F.R. § 42.8(B)(1))
`The real party-in-interest is Sirius XM Radio, Inc.
`
`
`
`
`2 Turin is an IEEE article that was publicly available as of March 1980. Ericsson
`
`Inc. v. Intellectual Ventures I LLC, IPR2014-00527, Paper 41 at 10-12 (May 18,
`
`2015) (copyright date of IEEE publication provided sufficient evidence of date of
`
`public availability); LG Elecs., Inc. v. Advanced Micro Devices, Inc., IPR2015-
`
`00329, Paper 13 at 12 (July 10, 2015) (“a copyright notice…[is] prima facie
`
`evidence of publication”); Ex. 1012 (conference date); Ex. 1011 (citing Turin
`
`under “OTHER PUBLICATIONS”); Lyon ¶¶118-19.
`
`
`
`- 3 -
`
`

`

`Petition for Inter Partes Review
`U.S. Patent No. 6,993,084
`
`
`B. Related Matters (37 C.F.R. § 42.8(B)(2))
`Patent Owner asserted the ‘3084 Patent against Petitioner in Fraunhofer-
`
`Gesellschaft zur Förderung der angewandten Forschung e.V. v. Sirius XM Radio
`
`Inc., 1:17-cv-00184 (D. Del. Feb. 22, 2017) (the “Litigation”). In addition to this
`
`petition, Petitioner has filed petitions for inter partes review of U.S. Patent Nos.
`
`6,314,289, 6,931,084 and 7,061,997, which Patent Owner also asserted against
`
`Petitioner in the Litigation. Shortly after the Patent Owner filed the Litigation,
`
`Petitioner filed a motion to dismiss on the grounds that Petitioner has had a license
`
`to the ‘3084 Patent—one granted to Petitioner by Patent Owner through an
`
`intermediary. Litigation at D.I. 10-13, 19-21, 29. That motion is currently pending
`
`before the District Court. Petitioner knows of no other matters that might affect or
`
`be affected by this requested inter partes review.
`
`C. Designation of Lead and Back-Up Counsel (37 C.F.R. §
`42.8(B)(3))
`
`Lead Counsel
`Jonathan S. Caplan
`jcaplan@kramerlevin.com
`Reg. No. 38,094
`
`Backup Counsel
`Mark A. Baghdassarian
`mbaghdassarian@kramerlevin.com
`Pro Hac Vice to be requested
`Jeffrey H. Price
`jprice@kramerlevin.com
`Reg. No. 69,141
`Shannon Hedvat
`shedvat@kramerlevin.com
`Reg. No. 68,417
`
`
`
`- 4 -
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`

`

`Petition for Inter Partes Review
`U.S. Patent No. 6,993,084
`
`
`Kramer Levin Naftalis & Frankel LLP
`1177 Avenue of the Americas
`New York, NY 10036
`Tel: 212.715.9100 Fax: 212.715.8000
`
`Service Information (37 C.F.R. § 42.8(B)(4))
`
`D.
`Please address all correspondence to the lead counsel at the address provided
`
`above Petitioner consents to service by email to the addresses identified above.
`
`III. PAYMENT OF FEES (37 C.F.R. § 42.103)
`Petitioner authorizes the U.S. Patent and Trademark Office to charge
`
`Deposit Account No. 50-0540 for the fee set in 37 C.F.R. § 42.15(a) for this
`
`Petition and for any additional fees.
`
`IV. REQUIREMENTS FOR INTER PARTES REVIEW UNDER
`37 C.F.R. §§ 42.104
`A. Grounds for Standing (37 C.F.R. § 42.104(A))
`Petitioner certifies that the ‘3084 Patent is eligible for inter partes review
`
`and that Petitioner is not barred or estopped from requesting inter partes review
`
`challenging the identified claims on the grounds set forth herein. Patent Owner
`
`filed and served Petitioner with its Litigation complaint asserting infringement of
`
`the ‘3084 Patent on February 22, 2017, and Petitioner has not filed a civil action
`
`challenging the validity of the ‘3084 Patent. Therefore, this Petition is timely filed.
`
`
`
`- 5 -
`
`

`

`Petition for Inter Partes Review
`U.S. Patent No. 6,993,084
`
`Identification of Challenged Claims (37 C.F.R. § 42.104(B)(1)) and
`Relief Requested (37 C.F.R. § 42.22(A)(1))
`
`B.
`
`Petitioner requests inter partes review of the Challenged Claims of the ‘3084
`
`Patent (i.e., claims 1-3, 6-12, 14-21 and 23) on the Grounds below, and requests
`
`that these claims be found unpatentable.
`
`C. The Prior Art and Specific Grounds on Which the Challenge to
`the Claims is Based (37 C.F.R. § 42.104(B)(2))
`
`The priority date for the ‘3084 Patent is April 14, 1998, the filing date of the
`
`PCT international stage application (PCT/EP98/02169) to which the ‘3084 Patent
`
`claims priority.
`
`Petitioner asserts that the Challenged Claims are unpatentable as follows:
`
`Ground
`1
`
`2
`
`3
`
`4
`
`5
`
`6
`
`
`
`Basis
`Claim(s)
`1, 2, 6, 7, 9, 18 Anticipated under § 102(e) by Cimini.
`1, 2, 6, 7, 9, 18 Obvious under § 103(a) by Cimini in view of
`ADSL and/or the knowledge of a POSA.
`
`11, 20
`
`Obvious under § 103(a) by Cimini in view of
`Palacherla (Patent Owner admitted prior art).
`3, 8, 10, 14, 19, 23 Obvious under § 103(a) by Cimini in view of
`Schmidl.
`
`12, 15, 21
`
`Obvious under § 103(a) by Cimini in view of
`Spilker.
`
`16
`
`Obvious under § 103(a) by Cimini in view of
`Spilker and further in view of Turin.
`
`- 6 -
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`

`

`Ground
`7
`
`Claim(s)
`17
`
`Petition for Inter Partes Review
`U.S. Patent No. 6,993,084
`
`
`Basis
`Obvious under § 103(a) by Cimini in view of
`Spilker and Turin and further in view of Schmidl.
`
`The discussions below and accompanying Declaration of Dr. Lyon (Ex.
`
`1002) lay out these bases for unpatentability.
`
`D. Claim Construction (37 C.F.R. § 42.104(B)(3))
`For purposes of this review, Petitioner construes the ‘3084 Patent claim
`
`language to give it its broadest reasonable construction in light of the specification
`
`(“BRI”). Because the BRI standard for claim construction at the USPTO is
`
`different than that used in District Court litigation, Petitioner reserves the right to
`
`argue a different claim construction in a different forum for any term in the ‘3084
`
`Patent as appropriate in that proceeding.
`
`V.
`
`SUMMARY OF THE ‘3084 PATENT AND ITS TECHNICAL FIELD
`A. Overview of the Technical Field
`1. Modulation
`The ‘3084 Patent concerns transmitting signals from transmitters to receivers
`
`in specific formats, with certain payload information contained in the transmitted
`
`signals, and then processing the received information. Lyon, ¶¶83-97. At the
`
`transmitter, the information to be sent is represented by a series of bits (1’s and
`
`0’s), which are mapped on to a sequence of symbols. Id., ¶¶40-43 (citing Proakis,
`
`
`
`- 7 -
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`

`

`719-728). These symbols are used to modify, or “modulate,” a carrier wave in a
`
`Petition for Inter Partes Review
`U.S. Patent No. 6,993,084
`
`
`specific way so that a signal can be electromagnetically transmitted to the receiver
`
`over one or more particular radio frequencies. Id.
`
`Communications systems typically use two carrier waveforms of the same
`
`frequency and differing in phase from one another when forming data bearing
`
`symbols through modulation. Lyon, ¶¶ 50-55 (citing Proakis at 225, 258-261).
`
`The two carriers differ by a constant phase difference of 90 degrees, equivalent to a
`
`quarter of a cycle (thus, they are referred to as “quadrature carriers”). Id. When
`
`modulation is applied to these quadrature carriers, a positive or negative amplitude
`
`will be assigned to one (the cosine) and a separate and independent amplitude to
`
`the other (the sine). Id. Although they oscillate at the same frequency, the
`
`modulated cosine and sine waveforms can be separated at the receiver due to a
`
`mathematical property known as “orthogonality.” Id.
`
`Modulated quadrature symbols may also be described using complex
`
`numbers. Id. Complex numbers have a real and imaginary part and are usually
`
`expressed in the form: a + jb, where j = √ -1. Id. Communications engineers refer
`
`to the amplitude of the modulated cosine carrier as the “real” part, and the
`
`amplitude of the modulated sine carrier as the “imaginary” part. Id.
`
`Modifying the amplitude of a signal and phase modulation are two ways to
`
`represent information as bits. By amplitude modulating both the cosine (real)
`
`
`
`- 8 -
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`

`

`carrier and sine (imaginary) carrier, a transmitter can produce amplitude and/or
`
`Petition for Inter Partes Review
`U.S. Patent No. 6,993,084
`
`
`phase modulated symbols.
`
`2. Multi-Carrier Modulation (MCM)
`OFDM is a technique for encoding digital information onto multiple sub-
`
`carrier frequencies that are transmitted simultaneously. Lyon, ¶¶56-65 (citing Zou
`
`at 2-5, Proakis; 258-269, 272-273, 702-713). OFDM, which is a type of MCM, is
`
`well suited to wireless communications because it performs well in multi-path
`
`systems with large delay spread, where the transmitted signal can propagate along
`
`multiple paths before reaching the receiver. Id.
`
`MCM/OFDM has a time and a frequency dimension. Lyon, ¶¶56-65 (citing
`
`Zou at 2-5; Proakis, 258-269, 272-273, 702-713. An MCM/OFDM symbol is
`
`made up of N subcarriers of different frequencies, and each subcarrier bears a
`
`complex subcarrier symbol. Id. These subcarrier symbols are transmitted
`
`sequentially in time, once per MCM/OFDM symbol, with modulation that
`
`represents the bits being transmitted. Id.
`
`Communications systems typically transmit multiple MCM/OFDM symbols
`
`in extended length structures referred to as “frames” (as in the ‘3084 Patent) or as
`
`“superframes.” Lyon, ¶¶66-81 (citing Lathi at 234-235; Zou at 3).
`
`
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`

`

`Petition for Inter Partes Review
`U.S. Patent No. 6,993,084
`
`
`
`
`As shown above, each frame is comprised of multiple MCM symbols each
`
`having a cyclic prefix (“CP”) or “guard interval.” Lyon, ¶¶66-81 (citing Lathi at
`
`234-235; Zou at 3). The guard interval adds some time between adjacent MCM
`
`symbols so that they will not interfere with each other, a problem known as “inter-
`
`symbol interference” (ISI). Id. Providing a guard interval between MCM symbols
`
`reduces ISI and makes it easier to properly receive and demodulate the signal. Id.
`
`3. MCM Frame Synchronization
`Because communications systems transmit frames containing multiple MCM
`
`symbols, mechanisms are needed for the receiver to determine where each frame
`
`begins in time. Lyon, ¶¶66-81 (citing Lathi at 234-235; Zou at 3). This well-
`
`known process of determining the start of the frame is “frame synchronization.”
`
`Id.
`
`To aid frame synchronization, as data is prepared for transmission, a
`
`“reference symbol” containing a fixed signal pattern is inserted at the start of each
`
`
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`- 10 -
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`

`

`frame to mark the beginning of the frame. Lyon, ¶¶66-81 (citing Lathi at 234-235;
`
`Petition for Inter Partes Review
`U.S. Patent No. 6,993,084
`
`
`Zou at 3). The receiver uses this reference symbol to determine the starting point
`
`of the MCM symbols that contain the bits being transmitted. Id. By determining
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`the starting position in time, the position of every other symbol is known because
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`the number of samples within the MCM symbol is a fixed, known value. Id.
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`The figure below illustrates the frame structure including the reference
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`symbol allowing a receiver to perform frame synchronization. Lyon, ¶¶66-81
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`(citing Lathi at 234-235; Zou at 3).
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`The reference symbol contains a reference pattern that may be defined by
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`the envelope of the amplitude modulation of a predetermined sequence of bits.
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`Lyon, ¶¶66-81 (citing Lathi at 234-235; Zou at 3). The envelope is the amplitude
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`of the modulated carrier. Id. The following shows a carrier amplitude modulated
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`by a bit sequence:
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`At the transmitter, the reference pattern and the envelope are the same
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`because the reference pattern is defined as the envelope of the transmitted signal.
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`Lyon, ¶¶66-81 (citing Lathi at 234-235; Zou at 3). However, as the channel
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`corrupts the amplitude of the signal on its way to the receiver, the envelope
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`changes. Id. The following shows the change in the envelope as received by the
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`receiver and the difference between the envelope and reference pattern. Id.
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`Because the reference pattern of the reference symbol is known by the
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`receiver, the receiver is programmed to search for and find the known reference
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`pattern from the envelope of the received signal. Id. When the receiver locates the
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`reference symbol by matching (i.e., correlating) to the reference pattern with the
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`received envelope, frame synchronization is achieved – i.e., the timing of the frame
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`containing the transmitted MCM symbols has been identified – and further
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`processing on the received signal may begin so that information may be extracted
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`from the transmitted signal symbols. Id.
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`The Fourier Transform
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`4.
`The Fourier Transform is a well-known mathematical operation by which a
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`signal that varies as a function of time is decomposed into its frequency
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`components, or “spectrum.” Lyon, ¶82. Similarly, an “inverse” Fourier Transform
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`is used to generate a time domain signal from the signal’s spectrum. The Fast
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`Fourier Transformation (“FFT”) process is a type of Fourier transformation
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`performed on digitized signal samples and is fundamental to the efficient
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`implementation of the MCM/OFDM communication process. Id. For example, in
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`MCM/OFDM the transmission of data typically requires Inverse Fast Fourier
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`Transformation (“IFFT”) to map the N complex subcarrier symbols to N complex
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`time domain discrete amplitudes (where N corresponds to the number of
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`subcarriers within the system). Id. Receiving data typically requires Fast Fourier
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`Transformation (“FFT”) to perform the opposite function, mapping the sampled
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`time domain amplitudes back to subcarrier symbols. Id. For OFDM systems, the
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`IFFT and FFT operations are essentially mathematically identical. Id.
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`B. Overview of the ‘3084 Patent
`The ‘3084 Patent describes techniques well-known in the prior art to combat
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`signal corruption (e.g., fading, shadowing, added noise, nonlinear distortion and
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`signal interference) that can occur during transmission so that the receiver can
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`achieve frame synchronization to retrieve the payload information transmitted to a
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`receiver. Lyon, ¶43 (citing Proakis at 719-728). According to the ‘3084 Patent, a
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`generated signal includes a reference symbol as part of the frame structure for
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`transmitting the signal via MCM in order to allow for and perform frame
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`synchronization of signals received by the receiver:
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`The present invention relates to methods and apparatus for generating
`a signal having a frame structure, wherein each frame of the frame
`structure is composed of useful symbols, a guard interval associated
`to each useful symbol and one reference symbol. In addition, the
`present invention relates to methods and apparatus for frame
`synchronization of signals having the above structure.
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`The present invention is particularly useful in a MCM transmission
`system
`(MCM=Multi-carrier modulation) using an orthogonal
`frequency division multiplexing (OFDM) for digital broadcasting.
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`Ex. 1001, 1:6–16 (emphasis added).
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`This frame structure is illustrated in FIG. 1 below:
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`To allow for frame synchronization by the receiver, the ‘3084 Patent
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`instructs that the reference symbol must be inserted in time domain as part of the
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`frame of the transmitted signal:
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`Performing the above described method, the following problem
`occurs in the receiver. The exact position of the guard interval and
`hence the position of the original useful parts of the time domain
`MCM symbols is generally unknown. Extraction of the guard interval
`and the subsequent FFT-transform of the resulting useful part of the
`time signal is not possible without additional information. To provide
`this additional information, a known (single carrier) sequence in the
`form of a (time domain) reference symbol is inserted into the time
`signal. With the knowledge about the positions of the reference
`symbols in the received signal, the exact positions of the guard
`intervals and thus the interesting information carrying time samples
`are known.
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`The periodical insertion of the reference symbol results in a frame
`structure of the MCM signal. This frame structure of a MCM signal is
`shown in FIG. 1. One frame of the MCM signal is composed of a
`plurality of MCM symbols 10. Each MCM symbol 10 is formed by an
`useful symbol 12 and a guard interval 14 associated therewith. As
`shown in FIG. 1, each frame comprises one reference symbol 16.
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`A functioning synchronization in the receiver, i.e. frame, frequency,
`phase, guard interval synchronization is necessary for the subsequent
`MCM demodulation. Consequently, the first and most important task
`of the base band processing in the receiver is to find and synchronize
`to the reference symbol.
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`Ex. 1001, 1:50–2:8 (emphasis added).
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`Indeed, the ‘3084 Patent specifically calls out the reference symbol as the
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`purported novelty of the claimed invention:
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`The present invention provides a novel structure of the reference
`symbol along with a method to determine the position of the reference
`symbol and thus the start of a frame in a signal having a frame
`structure as shown for example in FIG. 1.
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`Ex. 1001, 6:55–59.
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`The ‘3084 Patent further explains how the reference symbol is used for
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`frame synchronization:
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`The method is based on the detection of a known reference symbol of
`the frame header in the reception signal, e.g. in the digital complex
`baseband. The new frame synchronization will be performed as the
`first synchronization task.
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`Ex. 1001, 6:63–67.
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`The ‘3084 Patent then specifies the requisite attributes of the reference
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`symbol -- namely, that the information in the reference symbol used for frame
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`synchronization must be an amplitude modulated bit sequence:
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`[I]n accordance with the present invention, the form of the reference
`symbol selected is an amplitude modulated sequence (AM sequence)
`in the complex baseband. Thus, the information contained in the
`reference symbol is only that given in the amplitude and not that in
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`the phase.
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`Ex. 1001, 7:6–11.
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`An amplitude modulated bit sequence is used because the phase information
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`in a symbol may be corrupted or impaired due to the effects of frequency offset:
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`The information contained in the reference symbol must therefore be
`independent of other synchronization parameters, e.g. frequency
`offset. . . . Note that the phase information will be corrupted by a
`possible frequency offset.
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`Ex. 1001, 7:3-12 (emphasis added).
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`The ‘3084 Patent then explains that a correlation of the received reference
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`pattern with a replica of the pattern stored at the receiver is performed to achieve
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`frame synchronization:
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`In the receiver, the first step after the down-conversion of the received
`signal is to perform an amplitude-demodulation of the down-
`converted signal in order to generate an envelope, i.e. in order to
`determine the amplitude of the signal. This envelope is correlated
`with a replica reference pattern in order to detect the signal reference
`pattern of the reference symbol in the signal.
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`Ex. 1001, 8:15–21.
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`As discussed in the Overview of the Technical Field, the techniques of the
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`‘3084 Patent were well-known to POSAs at the time of the alleged invention.
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