`
`Patent No. 7,061,997
`Petition For Inter Partes Review
`
`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 IPR2018-______
`____________________
`
`PETITION FOR INTER PARTES REVIEW OF U.S.
`PATENT NO. 7,061,997 UNDER 35 U.S.C. §§ 311-319 AND 37 C.F.R. § 42
`
`Mail Stop Patent Board
`Patent Trial and Appeal Board U.S.
`Patent and Trademark Office
`P.O. Box 1450
`Alexandria, VA 22313-1450
`
`
`
`

`

`
`
`TABLE OF CONTENTS
`
`Page
`
`I.
`
`INTRODUCTION ........................................................................................... 1
`
`II. MANDATORY NOTICES (37 C.F.R. § 42.8) ............................................... 2
`A.
`Real Party-in-Interest (37 C.F.R. § 42.8(b)(1)) ..................................... 2
`B.
`Related Matters (37 C.F.R. § 42.8(b)(2)) .............................................. 3
`C.
`Designation of Lead and Back-Up Counsel (37 C.F.R. § 42.8(b)(3)) .. 3
`D.
`Service Information (37 C.F.R. § 42.8(b)(4)) ....................................... 3
`
`III.
`
`PAYMENT OF FEES (37 C.F.R. § 42.103) ................................................... 4
`
`IV. REQUIREMENTS FOR INTER PARTES REVIEW UNDER 37 C.F.R. §
`42.104 .............................................................................................................. 4
`A. Grounds For Standing (37 C.F.R. § 42.104(a)) .................................... 4
`B.
`Identification of Challenged Claims (37 C.F.R. § 42.104(b)(1)) .......... 4
`C.
`The Prior Art and Specific Grounds on Which the Challenge to the
`Claims is Based (37 C.F.R. § 42.104(b)(2)) ......................................... 5
`Claim Construction (37 C.F.R. § 42.104(b)(3)) .................................... 6
`
`D.
`
`V.
`
`PERSON OF ORDINARY SKILL IN THE ART .......................................... 9
`
`VI. SUMMARY OF THE ’997 PATENT AND ITS TECHNICAL FIELD ......10
`A. OVERVIEW OF THE TECHNICAL FIELD ....................................10
`B.
`Brief Description of the ’997 patent ....................................................15
`C.
`Summary of the Prosecution History ..................................................19
`
`VII. THERE IS A REASONABLE LIKELIHOOD THAT AT LEAST ONE
`CLAIM OF THE ’997 PATENT IS UNPATENTABLE .............................22
`A. Grounds 1 & 2 For UNPATENTABILITY ........................................23
`B.
`Ground 3 FOr UNPATENTABILITY ................................................41
`
`VIII. CONCLUSION ..............................................................................................54
`
`i
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`

`

`
`
`I.
`
`INTRODUCTION
`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 of U.S. 7,061,997 (Ex. 1007;
`
`“the ’997 Patent”). Petitioner asserts there is a reasonable likelihood that at least
`
`one claim is unpatentable and respectfully requests review of, and judgment
`
`against, these claims as unpatentable under 35 U.S.C. § 102 and/or § 103.
`
`The ’997 Patent discloses a mechanism to measure and correct for a
`
`particular type of error, called a frequency deviation, that occurs during multi-
`
`carrier modulation (“MCM”) transmission of a signal between a transmitter and
`
`receiver. See generally, Ex. 1007; Ex. 1001, ¶76. An MCM transmission is one
`
`whereby information is transmitted over a series of carrier frequencies, also called
`
`subcarriers, that carry symbols that contain the information to be transmitted. Ex.
`
`1001, ¶¶ 56-63. Frequency deviation between the transmitter and the receiver’s
`
`carrier frequencies causes phases of symbols on an individual subcarrier frequency
`
`to rotate. Ex. 1001, ¶ 63. The ’997 Patent recites methods that measure and
`
`correct for the frequency deviation through determinations of the phase differences
`
`and related frequency offsets of the symbols being transmitted over the MCM
`
`subcarriers, and then uses the average of the frequency offsets for each of the
`
`carriers in the MCM transmission to correct for the frequency deviations. Ex.
`
`1007, claim 1. This practice of measuring and correcting for frequency deviations
`
`1
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`

`

`
`
`in communications systems utilizing differential phase modulation between phases
`
`of the same subcarrier in different MCM symbols, i.e., phase differences in the
`
`time domain, was well-known in the art at the time the ’997 Patent was filed.
`
`Indeed, during prosecution of the ’997 patent, Applicants were unable
`
`to overcome well-known art related to measuring and correcting for frequency
`
`deviation. Instead, the claims were issued over the art based on the addition of a
`
`“wherein” clause that required averaging the frequency offsets determined for each
`
`individual frequency of an MCM transmission and then using the averaged value
`
`of the frequency offsets to correct for that frequency deviation. However, prior art
`
`that was not before the Examiner during prosecution clearly disclosed the
`
`challenged claims, including the wherein clause added to obtain issuance. Such art
`
`includes, at least, U.S. Patent No. 6,341,123 to Tsujishita (“Tsujishita”) (Ex. 1002)
`
`and Classen et al., Frequency Synchronization Algorithms for OFDM Systems
`
`Suitable for Communication over Frequency Selective Fading Channels, IEEE,
`
`1994 (“Classen”) (Ex. 1003).
`
`For the reasons set forth herein, Petitioner requests that the
`
`Challenged Claims be found unpatentable.
`
`II. MANDATORY NOTICES (37 C.F.R. § 42.8)
`A. REAL PARTY-IN-INTEREST (37 C.F.R. § 42.8(b)(1))
`Petitioner certifies that it is the real party-in-interest.
`
`2
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`

`

`
`
`B. RELATED MATTERS (37 C.F.R. § 42.8(b)(2))
`Patent Owner asserted the ’997 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”).
`
`Petitioner has also filed petitions for inter partes review of U.S. Patent Nos.
`
`6,314,289; 6,931,084 and 6,933,084, which Patent Owner also asserted against
`
`Petitioner in the foregoing litigation. Shortly after the Patent Owner filed the
`
`Litigation, Petitioner filed a motion to dismiss the Complaint on grounds that
`
`Petitioner has had a license to the ’997 Patent because of a license granted to
`
`Petitioner by the Patent Owner through an intermediary. Litigation at D.I. 10-13,
`
`19-21, 29. That motion is currently pending before the District Court.
`
`C. DESIGNATION OF LEAD AND BACK-UP COUNSEL (37
`C.F.R. § 42.8(b)(3))
`
`Lead Counsel
`
`
`Jonathan Caplan (Reg. No. 38,094)
`Kramer Levin Naftalis & Frankel LLP,
`1177 Avenue of the Americas
`New York, NY 10036
`Tel: 212.715.9100 Fax: 212.715.8000
`
`
`Back-Up Counsel
`
`
`Mark Baghdassarian (pro hac vice to
`be filed)
`Kramer Levin Naftalis & Frankel LLP,
`1177 Avenue of the Americas,
`New York, NY 10036
`Tel: 212.715.9100 Fax: 212.715.8000
`
`
`D.
`
`SERVICE INFORMATION (37 C.F.R. § 42.8(b)(4))
`
`Please address all correspondence to the lead counsel at the address
`
`provided in Section I(C) of this Petition. Petitioner also consents to service by
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`3
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`
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`email to: JCaplan@kramerlevin.com with a copy to
`
`MBaghdassarian@kramerlevin.com.
`
`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 ’997 Patent is eligible for inter partes
`
`review and that it is not barred or estopped from requesting inter partes review
`
`challenging the identified claims on the grounds set forth herein. Patent Owner
`
`served Petitioner with a complaint asserting infringement of the ’997 Patent on
`
`February 22, 2017, and Petitioner has not filed a civil action challenging the
`
`validity of the ’997 Patent. Therefore, this petition is timely filed.
`
`B.
`
`IDENTIFICATION OF CHALLENGED CLAIMS
`(37 C.F.R. § 42.104(b)(1))
`Petitioner requests inter partes review of claims 1-3 of the ’997 Patent
`
`(hereinafter, the “Challenged Claims”) on the grounds set forth below, and requests
`
`that these claims be found unpatentable.
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`4
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`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 ’997 Patent is April 14, 1998, the filing date
`
`of the PCT international stage application PCT/EP98/02184 to which the ’997
`
`Patent claims priority. Petitioner requests inter partes review of the ’997 Patent in
`
`view of the following prior art references: U.S. Patent No. 6,341,123 to Tsujishita
`
`(“Tsujishita”) and Classen et al., Frequency Synchronization Algorithms for
`
`OFDM Systems Suitable for Communication over Frequency Selective Fading
`
`Channels, IEEE, 1994 (“Classen”). 1
`
`The following specific grounds of invalidity are asserted:
`
`1 Classen is prior art to the ’997 Patent, as it is an IEEE publication that bears a
`
`copyright date of 1994. See Ericsson Inc. v. Intellectual Ventures I LLC, IPR2014-
`
`00527, Paper 41 at 10-12 (PTAB May 18, 2015) (holding that copyright date of
`
`IEEE publication was not hearsay and provided sufficient evidence of the date of
`
`public availability); Valeo N. Am., et al. v. Magna Elecs. Inc., IPR2015-01410,
`
`Paper 23 at 42–46 (PTAB Dec. 22, 2016); Ex. 1009 (IEEE webpage showing
`
`conference date); Ex. 1001, p. 1 note 1; Ex. 1010 (patent filed April 26, 1996,
`
`citing Classen on its face). See also 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”).
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`5
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`
`
`Ground
`1
`
`Claim(s)
`1-3
`
`Basis
`Anticipation under 35 U.S.C. § 102(e) by U.S. Patent
`No. 6,341,123 (“Tsujishita”) (Ex. 1002)
`
`2
`
`3
`
`1-3
`
`1-3
`
`Obviousness under 35 U.S.C. § 103 by Tsujishita (Ex.
`1002) in view of the knowledge of a person of ordinary
`skill in the art
`
`Obviousness under 35 U.S.C. § 103 by Tsujishita (Ex.
`1002) in view Classen et al., Frequency Synchronization
`Algorithms for OFDM Systems Suitable for
`Communication over Frequency Selective Fading
`Channels, IEEE, 1994 (“Classen”) (Ex. 1003)
`
`An explanation of the unpatentability of the Challenged Claims,
`
`including an identification of where each element is found in the prior art, is
`
`provided in the detailed claim charts in Section VII below. Additional support is
`
`set forth in the Declaration of David Lyon, PhD. (Ex. 1001).
`
`D. CLAIM CONSTRUCTION (37 C.F.R. § 42.104(b)(3))
`Pursuant to § 42.100(b), for the purposes of this review, Petitioners
`
`construe the claim language such that it is “given its broadest reasonable
`
`construction in light of the specification of the patent in which it appears” (“BRI”).
`
`The BRI of the claim language is the position the Patent Owner appears to have
`
`taken in the litigation. Because the BRI standard for claim construction at the
`
`USPTO is different than that used in District Court litigation (see In re Am. Acad.
`
`of Sci. Tech Ctr., 367 F.3d 1359, 1364, 1369 (Fed. Cir. 2004); MPEP § 2111),
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`6
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`
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`Petitioner reserves the right to argue a different claim construction in a different
`
`forum for any term in the ’997 Patent as appropriate in that proceeding.
`
`Petitioner requests a construction that the preamble of claim 1 is not
`
`limiting. The preamble of claim 1 recites “each symbol being differentially coded
`
`in the direction of the frequency axis.” Ex. 1007, claim 1. This portion of the
`
`preamble is entirely divorced from the body of the claim. This language recited in
`
`the preamble relates to coding and phase differences in the frequency axis or
`
`frequency domain. Ex. 1001, ¶ 97-99, ¶ 113-114. In contrast, the body of the
`
`claim relates to processing of received signals in the time domain. Id. Indeed, the
`
`frequency language of the preamble has no effect on, and is inconsequential to, the
`
`performance of the limitations in the body of the claim – that is, “deletion of the
`
`preamble phrase does not affect the structure of steps of the claimed invention.”
`
`See Am. Med. Sys., Inc. v. Biolitec, Inc., 618 F.3d 1354, 1358–59 (Fed. Cir. 2010)
`
`(“A preamble is not regarded as limiting ... when the claim body describes a
`
`structurally complete invention such that deletion of the preamble phrase does not
`
`affect the structure of steps of the claimed invention.”). Because of the disconnect
`
`between the preamble and body of the claim, the preamble should not be limiting.
`
`To the extent that the preamble phrase “being differentially coded in
`
`the frequency axis direction” is found to be limiting (which it is not), and therefore
`
`requires each symbol to be differentially coded in the frequency axis direction, the
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`7
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`

`
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`claims would be indefinite because a POSA would not understand whether the
`
`claims covered coding symbols in the frequency domain or the time domain. Ex.
`
`1001, ¶ 97-99. As set forth below, in claim limitation 1a, the claim makes clear
`
`that coding is in the time domain. See Ex. 1007, claim 1. Further, claim 2 recites a
`
`claim element comprising a “step of determining a phase difference between
`
`phases of the same carrier in symbols which are adjacent in the time axis
`
`direction.” See Ex. 1007, claim 2. Thus, if the preamble is limiting, the claim
`
`limitations of 1a and claim 2 contradict the preamble’s recitation of coding in the
`
`direction of the frequency axis, and a POSA would not understand the claims
`
`limitations recited. Id. Alternatively, if the preamble is determined to be limiting
`
`and the claims require coding in the direction of the frequency axis, it was well-
`
`known to a POSA that corrections for frequency offsets in the time domain could
`
`also be applied to such corrections in the frequency domain. Id. See also Ex.
`
`1006, p. 273 (describing differentially encoding symbols in frequency as an
`
`alternative to differentially encoding symbols in time to improve system
`
`performance under certain circumstances, e.g., in systems with large delay spread
`
`to avoid loss of data rate that can occur when using the time domain approach).2
`
`2 Ex. 1006, Moose 1990, is prior art to the ’997 Patent, as it is an IEEE publication
`
`that bears a copyright date of 1990. See Ericsson Inc. v. Intellectual Ventures I
`
`LLC, IPR2014-00527, Paper 41 at 10-12 (PTAB May 18, 2015) (holding that
`
`8
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`

`
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`Thus, the art cited herein that supports anticipation and/or obviousness of the claim
`
`elements of correcting for frequency offset in the time domain (claim limitations
`
`1a and 2) would also render the preamble claim phrase “being differentially coded
`
`in the frequency axis direction” anticipated and/or obvious. Id.
`
`V.
`
`PERSON OF ORDINARY SKILL IN THE ART
`
`Petitioner submits that the applicable person of ordinary skill in the art
`
`(“POSA”) would have a minimum of a bachelor's degree in Electrical Engineering
`
`and three or more years of industry experience relating to design, installation,
`
`and/or operation of digital, wireless communication networks operating over
`
`satellite and terrestrial channels and utilizing various modulation methods
`
`including multi-carrier modulated systems. Ex. 1001, ¶ 33-35.
`
`
`copyright date of IEEE publication was not hearsay and provided sufficient
`
`evidence of the date of public availability); Valeo N. Am., et al. v. Magna Elecs.
`
`Inc., IPR2015-01410, Paper 23 at 42–46 (PTAB Dec. 22, 2016); Ex. 1009 (IEEE
`
`webpage showing conference date); Ex. 1001, p. 51 note 2. See also 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”).
`
`9
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`
`
`VI. SUMMARY OF THE ’997 PATENT AND ITS TECHNICAL FIELD
`A. OVERVIEW OF THE TECHNICAL FIELD
`The ’997 Patent generally relates to a mechanism to correct for
`
`corruption in a signal that occurs in communication systems between a transmitter
`
`and receiver. Ex. 1001, ¶¶ 37-42. To transport information, the information to be
`
`sent is represented by a series of bits (1’s and 0’s). These bits are mapped on to a
`
`sequence of symbols that are used to modify a carrier wave through modulation so
`
`that a signal may be electromagnetically transmitted, for example via an antenna
`
`over particular radio frequencies to the receiver. Ex. 1001, ¶40.
`
`Two of the more common forms of modulation found in the prior art
`
`are amplitude modulation and phase modulation. Ex. 1001, ¶ 46, citing Ex. 1022 at
`
`p. 12. Amplitude modulation refers to modifying the amplitude, (i.e. peak to peak
`
`size), of the carrier in order to convey information. Ex. 1001, ¶ 47-48, citing Ex.
`
`1022, pp. 12-13, 223-224, 234-235. For example, an amplitude of 1.0 in a carrier
`
`might represent a ‘0’ bit and an amplitude of 2.0 in that same carrier might
`
`represent a ‘1’ bit. Id. And so, the sequence of bits “00101110” (which might
`
`represent audio information that is to be transmitted) would be represented by the
`
`amplitudes of 1.0 and 2.0. Ex. 1001, ¶ 47, Fig. 2.
`
`Phase modulation is another mechanism to transport bits. Ex. 1001,
`
`¶¶ 49-63. The simplest form of phase modulation is called “binary phase shift
`
`10
`
`

`

`
`
`keying” (also known as “BPSK”). Ex. 1001, ¶ 50, citing Ex. 1021, p. 232, 245.
`
`By way of example, in BPSK, a 0 bit corresponds to a starting phase of the symbol
`
`of a carrier at 0° and a 1 bit corresponds to a starting phase of a symbol of a carrier
`
`at 180°. And so, the sequence of bits “00101110” described above would be
`
`represented by the phases 0° and 180°. Ex. 1001, ¶ 50-52, citing Ex. 1021, pp. 225-
`
`226, 232 245, Fig. 3 and Fig. 4. Four phases can also be used to give two bits per
`
`symbol whereby the symbols and their corresponding phases are: ‘00’ with a phase
`
`of 0°, ‘01’ with phase 90°, ‘10’ is -90°, and ‘11’ is 180°. Ex. 1001, ¶ 53, Fig. 5,
`
`citing Ex. 1021, pp. 265-271. These four points all have the same amplitude and
`
`are differentiated from each other by their phase. Grouping bits together in pairs
`
`and mapping them to these four different phases is called Quadrature Phase Shift
`
`Keying (“QPSK”). Id.
`
`Amplitude modulated schemes and BPSK and QPSK modulation
`
`schemes are transmitted in symbols using various transmission mechanisms. Ex.
`
`1001, ¶¶ 40, 49-50, 53-54, citing Ex. 1021, pp. 225, 232, 245. One of those
`
`transmission mechanisms is called multi-carrier modulation (“MCM”)
`
`transmissions. Ex. 1001, ¶ 56-63, citing Ex. 1023 at pp. 2-5 MCM is also
`
`commonly referred to as OFDM (which stands for Orthogonal Frequency Division
`
`Multiplexing) and is a transmission mechanism whereby information is transmitted
`
`over a series of carrier frequencies (akin to the transmission of information over a
`
`11
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`

`

`
`
`number of skinny pipes) as opposed to a single carrier frequency transmission
`
`(akin to the transmission of information over one large pipe), as shown in the
`
`illustration below:
`
`Ex. 1001, ¶¶ 55-56, Fig. 7, citing Ex. 1023 at p. 2.
`
`
`
`For an MCM transmission of QPSK symbols, the sequence of QPSK
`
`symbols are “mapped” onto subcarriers in the MCM system. Ex. 1001, ¶ 58. The
`
`following figure shows an example of this for six subcarriers (for a single MCM
`
`symbol) at the transmitter for the bit sequence ‘010110110010’:
`
`12
`
`
`
`

`

`
`
`Ex. 1001, ¶ 58, Fig. 8.
`
`MCM has a time and a frequency dimension as illustrated below:
`
`
`
`Ex. 1001, ¶ 59, Fig. 9, citing Ex. 1023, pp. 3-4.
`
`The first dimension in an MCM transmission is the “frequency”
`
`dimension. Ex. 1001, ¶¶ 59-60, citing Ex. 1023, pp. 3-4. Each set of subcarrier
`
`symbols is transmitted over its own distinct frequency and each unit in the
`
`frequency direction is called a “subcarrier.” Id. The frequency dimension in the
`
`figure above is represented by each of the subcarriers – i.e., SC1 represents
`
`subcarrier 1; SC2 represents subcarrier 2; SC3 represents subcarrier 3; and so on
`
`until the last subcarrier, which is SC100 in the figure above. Id.
`
`The second dimension is the “time” dimension and each complete unit
`
`in the time direction (containing all the subcarriers in frequency) is called an MCM
`
`or OFDM symbol. Ex. 1001, ¶ 59-62, citing Ex. 1023, p. 3. Each individual
`
`subcarrier carries a number of subcarrier symbols over time, and those symbols are
`
`13
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`

`
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`transmitted one at a time on each individual subcarrier. Id. In the figure above, the
`
`subcarrier symbols are represented by the rows of colored boxes, one MCM
`
`symbol per row of uniform color. Ex. 1001, ¶ 61, Fig. 9. In the figure, SC1
`
`represents the first subcarrier of the MCM transmission and the individually
`
`colored boxes represent each of the subcarrier symbols found on that subcarrier
`
`over some period of time. SC2 represents the second subcarrier and the
`
`individually colored boxes represent each of the subcarrier symbols found on that
`
`subcarrier. Id.
`
`An MCM transmission can have hundreds of subcarriers with each
`
`subcarrier carrying sequences of subcarrier symbols. Id. For purposes of this
`
`illustration, the above figure shows 100 subcarriers with each subcarrier carrying
`
`three subcarrier symbols in three successive symbol periods. Id.
`
`When a receiver receives transmitted signals, such as through the
`
`MCM transmission described above, it processes them to retrieve the information
`
`(such as digitized audio content) that was originally transmitted. Ex. 1001, ¶42,
`
`citing Ex. 1021, pp. 719-728. When the signal becomes corrupted during
`
`transmission by one or more of the well-known causes of corruption (such as
`
`fading, shadowing, added noise, nonlinear distortion, and interference from other
`
`signals), receivers employ a variety of well-known techniques to mitigate and
`
`compensate for these sources of corruption, such that the receiver can successfully
`
`14
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`

`
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`estimate (i.e., retrieve) the information bits that were originally sent by the
`
`transmitter. Id. This corruption can include amplitude distortion (i.e., not all
`
`signals experience the same amplitude gain during transmission), carrier phase
`
`rotation (i.e., the entire signal is systematically rotated in the complex plane due to
`
`a mismatch in frequency or phase between the radio transmitter and the radio
`
`receiver), and phase distortion (i.e., phase delays experienced by the signals that
`
`vary among the subcarriers). Ex. 1001, ¶ 63, citing Ex. 1021, pp. 258-269, 272-
`
`273, 702-713. These various forms of corruption are constantly changing, and so
`
`the receiver must account for and correct for those changes. Id.
`
`An issue that occurs, particularly with MCM transmissions, is a
`
`mismatch between the carrier frequency of the transmitted signal and the carrier
`
`frequency the receiver expects – referred to as a “frequency offset.” Ex. 1001, ¶66.
`
`The impact of this frequency offset is to rotate the phase of the subcarrier symbols
`
`from one OFDM symbol to the next. Ex. 1001, ¶¶ 64-75. This causes problems in
`
`successfully receiving the transmitted signal and extracting the data from it. Id.
`
`B.
`
`BRIEF DESCRIPTION OF THE ’997 PATENT
`
`The ’997 Patent discloses a mechanism to measure the size of a
`
`frequency offset in the time domain and correct for it so that the receiver can
`
`process the transmitted signal and extract the information from the data bits found
`
`in the signal:
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`15
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`
`
`The present invention relates to methods and apparatus
`for performing a fine frequency synchronization
`compensating for a carrier frequency deviation from an
`oscillator frequency. This fine frequency synchronization
`is preferably performed after completion of a coarse
`frequency synchronization, such that the frequency
`offsets after the coarse frequency synchronization are
`smaller than half the sub-carrier distance in the MCM
`signal. Since the frequency offsets which are to be
`corrected by the inventive fine frequency
`synchronization methods and apparatus, a correction of
`the frequency offsets by using a phase rotation with
`differential decoding and de-mapping in the time axis
`can be used. The frequency offsets are detected by
`determining the frequency differences between time
`contiguous sub-carrier symbols along the time axis. The
`frequency error is calculated by measuring the rotation of
`the I-Q Cartesian coordinates of each sub-carrier and, in
`preferred embodiments, averaging them over all n sub-
`carriers of a MCM symbol.
`
`Ex. 1007, col. 3:42-59 (emphasis added).
`
` See also Ex. 1001, ¶¶ 76-80.
`
`The Challenged Claims outline a number of steps to perform this
`
`correction of the frequency offset as shown in claim 1 recited below:
`
`[Preamble] 1. A method of performing a fine frequency
`synchronization compensating for a carrier frequency
`deviation from an oscillator frequency in a multi-carrier
`demodulation system capable of carrying out a
`differential phase decoding of multi-carrier modulated
`signals, said signals comprising a plurality of symbols,
`each symbol being differentially coded in the direction of
`the frequency axis, said method comprising the steps of:
`[1a] a) determining a phase difference between phases of
`the same carrier in different symbols;
`
`16
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`
`
`[1b] b) determining a frequency offset by eliminating
`phase shift uncertainties related to the transmitted
`information from said phase difference making use of a
`M-PSK decision device; and
`[1c] c) performing a feedback correction of said carrier
`frequency deviation based on said determined frequency
`offset, wherein
`[1d] said steps a) and b) are performed for a plurality of
`carriers in said symbols,
`[1e] an averaged frequency offset is determined by
`averaging said determined frequency offsets of said
`plurality of carriers, and
`[1f] said feedback correction of said frequency deviation
`is performed based on said averaged frequency offset.
`
`Ex. 1007, claim 1 (brackets added to delineate claim elements for discussion). See
`
`also Ex. 1001, ¶¶ 81-91.
`
`Limitation 1a is the first step and requires “determining a phase
`
`difference between phases (i.e., angles) of the same carrier in different symbols.”
`
`Ex. 1007, claim 1. This is determining the phase difference (also referred to as a
`
`phase offset) in the phases (or angles) between adjacent symbols (e.g., between
`
`Symbol 1 and Symbol 2) on the same carrier frequency. To calculate the phase
`
`difference between two symbols on the same carrier, the phase of the first symbol
`
`is subtracted from the phase of the second symbol. Ex. 1001, ¶ 82. This step is
`
`done for each of the “plurality of carriers in said symbols” as required by limitation
`
`1d. Ex. 1007, claim 1.
`
`17
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`

`
`
`In the next step, limitation 1b requires “determining a frequency
`
`offset” and eliminating phase shift uncertainties related to the transmitted
`
`information from said phase difference to determine respective phase deviations
`
`through the use of a “M-PSK decision device.” Ex. 1007, claim 1; Ex. 1001, ¶ 83.
`
`A frequency offset must be determined for a plurality of the determined phase
`
`differences (limitation 1d). Ex. 1007, claim 1; Ex. 1001, ¶¶ 84-85. The claim
`
`requires determining an “averaged frequency offset” (limitation 1e) and then
`
`“performing a feedback correction of said carrier frequency deviation” (limitation
`
`1c) based on the determined “averaged frequency offset” (limitation 1f). Id.
`
`Dependent Claim 2 recites a limitation “wherein said step a)
`
`comprises the step of determining a phase difference between phases of the same
`
`carrier in symbols which are adjacent in the time axis direction” – that is, to
`
`determine the phase difference between symbol 1 and 2 on the same carrier
`
`frequency, then symbol 2 and 3 on the same carrier frequency, and so on. See Ex.
`
`1007, claim 2. Claim 2 is merely reciting the time axis direction, even though
`
`claim 1 already makes that limitation clear. Ex. 1001, ¶¶ 87-89.
`
`
`
`Dependent Claim 3 recites a limitation “wherein step b) comprises the
`
`step of eliminating phase shift uncertainties corresponding to M-ary phase shifts.”
`
`Ex. 1007, claim 2. M-ary phase shifts refers to mapping wherein M designates the
`
`18
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`
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`number of phase states used for encoding the subcarriers, for example 2, 4, 8, 16.
`
`See Ex. 1001, ¶ 90, citing Ex. 1007, col. 9:7-10.
`
`SUMMARY OF THE PROSECUTION HISTORY
`
`C.
`The prosecution history of the ’997 patent demonstrates that the limitations
`
`of the claimed invention were known in the art and that the claims were issued
`
`over the art only because of a “wherein” clause added to issued claim 1 during
`
`prosecution.
`
`During prosecution, claim 1 evolved from pending claim 19:3
`
`A method of performing a fine frequency
`synchronization compensating for a carrier frequency
`deviation from an oscillator frequency in a multi-carrier
`demodulation system of the type capable of carrying out
`a differential phase decoding of multi-carrier modulated
`signals, said signals comprising a plurality of symbols,
`each symbol being defined by phase differences between
`simultaneous carriers having different frequencies, said
`method comprising the steps of:
`a) determining a phase difference between phases
`of the same carrier in different symbols;
`b) determining a frequency offset by eliminating
`phase shift uncertainties related to the transmitted
`information from said phase difference making use of a
`M-PSK decision device; and
`
`
`3 Pending claims 19, 23 and 24 of the October 13, 2000 Preliminary Amendment
`
`issued as claims 1, 2 and 3 of the ’997 patent, after amendment of claim 19 during
`
`prosecution. Pending claims 23 and 24 depend from pending claim 19.
`
`19
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`

`
`
`c) performing a feedback correction of said carrier
`frequency deviation based on said determined frequency
`offset.
`
`Ex. 1005, 10/13/00 Preliminary Amendment.
`
`Throughout prosecution, this claim was repeatedly rejected as anticipated.
`
`For example, the pending claims were rejected as anticipated by U.S. Patent
`
`5,345,440 (“Gledhill”) (Ex. 1004). See Ex. 1005, 06/06/2004 Office Action at 3-4.
`
`The Examiner cited Gledhill as disclosing the method of certain pending claims,
`
`including claims 19, 23 and 24, and each of recited steps a, b, and c of claim 19.
`
`See Ex. 1005, 06/06/2004 Office Action at p. 3-4. Applicants attempted to argue
`
`over the rejection without amending the claims over the art.4 See Ex. 1005,
`
`09/23/04 Amendment and Remarks at p. 7-8. The Examiner maintained the
`
`rejection. See Ex. 1005, 1/12/05 Office Action at p. 2-4.
`
`Applicants then attempted to amend the claims to overcome the anticipation
`
`rejection. For example, the preamble of pending claim 19 was amended to delete
`
`the phrase “defined by phase differences between simultaneous carriers having
`
`different frequencies” and to replace it with the phrase “differentially coded in the
`
`
`4 A minor amendment of deleting the phrase “type capable of” in the preamble was
`
`entered in order to overcome a § 112(2) rejection. See Ex. 1005, 09/23/04
`
`Amendment and Remarks at p. 2.
`
`20
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`

`
`
`direction of frequency axis.” See Ex. 1005, April 26, 2005 Amendment and
`
`Remarks at p. 2, 8-9; see also 05/18/05 Response to Non-Compliant Amendment
`
`at p. 2. The examiner, however, maintained the anticipation rejection over Gledhill
`
`(Ex. 1004), finding that it discloses every element of the recited claims 19, 23 and
`
`24. See Ex. 1005, 08/06/05 Office Action at p. 2-4.
`
`In order to overcome the anticipation rejection over Gledhill, claim 19 was
`
`amended to add the “wherein” clause of issued claim 1. Pending claim 19, as
`
`amended and subsequently issued as claim 1, reads as follows:
`
`A method of performing a fine frequency
`synchronization compensating for a carrier frequency
`deviation from an oscillator frequency in a multi-carrier
`demodulation system [of the type capable of] carrying
`out a differential phase decoding of multi