Declaration of Douglas Chrissan, PhD
`IPR2016-01006, -01007, -01008, -01009 
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`EXPERT DECLARATION OF DOUGLAS CHRISSAN, PhD
`FOR
`INTER PARTES REVIEW NOS. IPR2016-01006, -01007, -01008, -01009
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`i
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`TQ Delta Exhibit 2001
`Cisco Systems, Inc. v. TQ Delta LLC
`IPR2016-01009
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`Declaration of Douglas Chrissan, PhD
`IPR2016-01006, -01007, -01008, -01009 
`
`I.
`
`INTRODUCTION & SUMMARY OF OPINIONS
`
`1. My name is Douglas A. Chrissan. I have been engaged by TQ Delta,
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`LLC in connection with IPR numbers 2016-01006 (relating to U.S. Pat. No.
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`7,835,430 (“the ‘430 patent”)), -01007 (relating to U.S. Pat. No. 8,432,956 (“the
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`‘956 patent”)), -01008 (relating to U.S. Pat. No. 8,238,412 (“the ‘412 patent”)),
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`and -01009 (also relating to the ‘412 patent”) before the United States Patent and
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`Trademark Office. In this declaration I provide my opinion that the challenged
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`claims of the ’430, ’412 and ’956 patents, collectively the “Diagnostic Mode
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`Patents,” are not anticipated or obvious in view of the references and grounds
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`asserted by the Petitioner, Cisco Systems, Inc. (“Cisco”).1
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`II.
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`PROFESSIONAL QUALIFICATIONS
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`A. Background and Experience
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`2.
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`I am presently a technical consultant in the areas of communications
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`systems, multimedia systems, computer systems, and digital signal processing.
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`3.
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`I earned a B.S. and M.S. in Electrical Engineering from the University
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`of Southern California in 1988 and 1990, respectively, and a Ph.D. in Electrical
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`Engineering from Stanford University in 1998.
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`                                                            
`1 When referring to exhibits, I note that Cisco’s exhibits are identical across the four IPR proceedings except for Ex.
`1001 (the relevant patent at issue) and Exhibit 1009 (Kiaei declaration), which I will cite specifically. TQ Delta’s
`exhibits are also identical across the four IPRs (including my global declaration). In addition, when I address a
`given argument made by Cisco or Cisco’s expert, my comments are intended to address that argument whereever it
`is present in each of the IPRs. Also, I understand that in the 1006 IPR, Dish Network has joined as a petitioner, and
`that motions for joinder are pending with respect to other of the IPRs; my opinions are directed to the Petitioners
`collectively, as they rely on the same petition and same declaration of Dr. Kiaei. 
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`1
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`4.
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`5.
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`A copy of my current CV is attached.
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`I was a Masters Fellow and Member of the Technical Staff at Hughes
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`Aircraft Company in El Segundo, California, from 1988–1993. While at Hughes
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`Aircraft, I designed and developed communication systems for commercial and
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`military spacecraft, including for the MILSTAR satellite program.
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`6.
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`Between 1992 and 1993, while at Hughes Aircraft Company, I
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`designed and built a
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`state-of-the-art, 800 megabit-per-second
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`(Mbps)
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`telecommunications modem for the NASA Lewis Research Center.
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`7.
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`From 1997–2003, I worked at 8x8, Inc., starting as a DSP software
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`engineer in 1997, becoming a manager in 1998, a director in 1999, and Vice
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`President of Engineering in 2000 (managing a team of approximately 60 engineers
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`in the company’s microelectronics group). I played a key role in developing
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`several
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`semiconductor products used worldwide
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`in multimedia
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`and
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`communications devices, mainly for video conferencing systems and Internet
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`Protocol (“IP”) telephones. Some of these semiconductor products were in
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`production more than ten years.
`
`8.
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`From 2003–2007, I was a Systems Architect and Engineering
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`Program Manager at Texas Instruments in the Digital Subscriber Line (“DSL”)
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`product business unit. At Texas Instruments, I was directly involved in the
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`architecture, design, development and production of multicarrier DSL modem
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`2
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`products. My work specifically included architecting a multicarrier DSL
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`semiconductor and software product and managing all aspects of its development
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`from inception to production.
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`9. My Ph.D. dissertation and related publications are in the fields of
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`statistical signal processing and communication systems, and more specifically in
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`the area of impulsive noise modeling for communication systems.
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`10.
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`In 1995 I was the instructor for the graduate Statistical Signal
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`Processing class (EE278) in the Electrical Engineering department at Stanford
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`University. Prior to teaching this class, I was a teaching assistant for ten different
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`classes in signal processing and radio frequency electronics at Stanford.
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`11.
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`I have developed, and managed the development of, several
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`successful semiconductor, software and systems products in the communications
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`and multimedia fields. These products are listed in the attached curriculum vitae.
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`B. Compensation
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`12.
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`I am being compensated for my time in this case at the rate of $250
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`per hour (plus expenses) for analysis, depositions, and, if necessary, trial
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`testimony. My compensation for this matter is not determined by or contingent on
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`the outcome of this case.
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`C. Materials Relied Upon
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`13.
`
`I reviewed and considered the challenged TQ Delta patents and their
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`prosecution histories, Cisco’s petitions, the references asserted by Cisco against the
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`TQ Delta patents, the other documents provided by Cisco in its petitions (including
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`the declarations of Dr. Sayfe Kiaei), the transcript of Dr. Kiaei’s deposition, and
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`other documents cited below.
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`III. BACKGROUND
`
`A. Technical Overview of the ‘430, ‘956, and ‘412 Patents
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`14. The Diagnostic Mode Patents claim improvements to multicarrier
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`transceiver devices used for data communication. The multicarrier transceivers
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`disclosed in the Diagnostic Mode Patents are capable of communicating certain
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`specified test and diagnostic information about the communication channel over
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`which the multicarrier transceiver communicates, as recited in the Diagnostic
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`Mode Patent claims.
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`15. The claims claim are all related. In all of the challenged claims of the
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`‘430, ‘956, and ‘412 patents, bits in a diagnostic message or test message must be
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`transmitted or received using DMT/QAM (“Discrete Multitone” / “Quadrature
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`Amplitude Modulation”) with more than 1 bit per subchannel, and the given
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`parameter must be transmitted or received in an “array.” The claims differ by
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`variously requiring transmitting or receiving either test information or diagnostic
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`information that includes different ones of the measured parameters.
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`16. Claims 1-8 of the ‘956 patent and claims 1-8 and 21 of the ‘412 patent
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`require transmitting or receiving an array representing “power level per subchannel
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`information.” The power level per subchannel information corresponds to the
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`power level measured by the remote transceiver on the different subchannels of the
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`multicarrier communication channel. See, e.g., ’956 patent, 4:31–40. The power
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`level per subchannel information allows characterization across the frequency
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`spectrum of the multicarrier communication channel used by the multicarrier
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`transceiver. Because this information is generated by an already-installed remote
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`transceiver and may be communicated to a more convenient location (e.g., a near-
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`end transceiver located in a service provider’s central office), the need to send out
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`a service technician with complex test equipment, such as a spectrum analyzer or
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`line analyzer, is eliminated.2
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`17. Subchannels experiencing excessive attenuation (i.e.,
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`impaired
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`subchannels) will be associated with lower power levels per subchannel values in
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`general. Because the near-end transceiver has knowledge of the transmit power
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`level at which the transmission signal (e.g., a Reverb signal) was transmitted, and
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`because the power level per subchannel information is representative of the power
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`levels of the different subchannels as measured by a remote transceiver, the near-
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`                                                            
`2 The terms “remote” transceiver and “near-end” transceiver in this declaration are used by way
`of example. They are not found in the challenged claims and are not intended to indicate
`geographic location, other than to the extent it is advantageous from a system and service
`standpoint to have certain information located or generated in a remote transceiver be available
`at a near-end transceiver.
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`end transceiver can compare the information representative of the transmitted
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`power level per subchannel with the information representative of the received
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`power level per subchannel to identify the subchannels that are experiencing
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`excessive attenuation.
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`18. Claims 2, 4, 6, and 8 of the ‘956 patent and claims 2, 4, 6, and 8 of the
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`‘412 patent recite the same thing as above, except the parameter is “power level
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`per subchannel information . . . based on a Reverb signal” instead of just “power
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`level per subchannel information.”
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`19. Claims 9–10 of the ‘956 patent and claims 13–14, 15 of the ‘412
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`patent require transmitting and receiving an array representing “Signal to Noise
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`ratio per subchannel during Showtime information.” The “Signal to Noise ratio
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`per subchannel during Showtime information” is representative of the ratio of
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`signal power to noise power of subchannels, measured by the remote transceiver
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`during normal data communication that occurs after initialization. The claims
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`provide that the information is communicated as an array, meaning that each entry
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`in the array corresponds to a value representative of the SNR values for the
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`subchannels.
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`20. The near-end transceiver may use the SNR per subchannel during
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`Showtime information to analyze the condition of the link. See ’412 at 4:32–34.
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`For example, link condition may be analyzed over time to identify service
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`degradation as system deployment grows with the addition of new communication
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`links (e.g., from adding new customers) that create increased crosstalk.
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`21. Claims 1–6 of the ’430 patent and claims 9–12 and 16–18 of the ’412
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`patent require transmitting and/or receiving an array representing “frequency
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`domain received idle channel noise information.” The frequency domain received
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`idle channel noise information corresponds to the idle channel noise measured by
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`the remote transceiver at different subchannels. The frequency domain idle
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`channel noise information allows characterization across the subchannels of the
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`multicarrier communication channel used by the multicarrier transceiver. Because
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`this information is generated by an already-installed transceiver and may be
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`communicated to a more convenient location (i.e., a near-end transceiver), again,
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`the need for a service technician visit may be eliminated. Also, because the
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`frequency domain received idle channel noise information is representative of the
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`idle channel noise measured by the remote transceiver for subchannels of the
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`multicarrier communication channel, the result is that the near-end transceiver
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`itself, a monitoring system and/or a technician may identify subchannels that are
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`experiencing excessive background noise, impulse noise or crosstalk.
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`22. The above described features of the claims of the Diagnostic Mode
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`Patents facilitate remote diagnosis of potential service problems through detailed
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`characterization of the multicarrier communication channel. This helps avoid a
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`costly site visit by a technician. See, e.g., ’430 patent, 2:20–24.
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`B.
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`23.
`
`The Board’s Institution Decisions
`
`In each of the four IPR proceedings, I understand the Board granted
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`review based on a single obviousness ground premised on the same primary
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`reference: U.S. Patent No. 6,636,603 to Milbrandt (“Milbrandt”). Specifically,
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`the Board granted review of claims 1–10 of the ’956 patent (IPR2016-01007)
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`and claims 1-8, 13–14, 19–20 of the ‘412 patent (IPR2016-01008) based on the
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`following, which also includes references U.S. Pat. No. 6,590,893 to Hwang et
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`al. (“Hwang”) and the ANSI T1.413-1995 Standard (“ANSI T1-413”):
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`Ground 1. Unpatentability of claims 1–10 under 35 U.S.C. § 103(a) over
`U.S. Patent No. 6,636,603 to Milbrandt (“Milbrandt”), in view of U.S. Pat.
`No. 6,590,893 to Hwang et al. (“Hwang”) and American Nat. Standards
`Inst. (ANSI) T1.413-1995 Standard, entitled “Network and Customer
`Installation Interfaces—Asymmetric Digital Subscriber Line (ADSL)
`Metallic Interface” (“ANSI T1.413”).
`
`I further understand that the instituted grounds in IPR2016-01006 and -01009
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`add an additional reference, U.S. Pat. No. 6,891,803 to Chang et al. (“Chang”), to
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`the combination. The Board granted review of claims 1–6 of the ’430 patent
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`(IPR2016-01006) and claims 9–12, 15–18, and 21 of the ’412 patent (IPR2016-
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`01009) based on the following ground:
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`Ground 1. Unpatentability under 35 U.S.C. § 103(a) over U.S. Patent No.
`6,636,603 to Milbrandt (“Milbrandt”), in view of U.S. Pat. No. 6,891,803 to
`Chang et al. (“Chang”), U.S. Pat. No. 6,590,893 to Hwang et al. (“Hwang”),
`and American National Standards Institute (ANSI) T1.413-1995 Standard,
`entitled “Network and Customer Installation Interfaces—Asymmetric Digital
`Subscriber Line (ADSL) Metallic Interface” (“ANSI T1.413”)
`
`
`C. Legal Standards Applied
`
`24.
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`I am not an expert in patent law, and I am not purporting to provide
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`any opinions regarding the correct legal standards to apply in these proceedings. I
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`have been asked, however, to provide my opinions in the context of the following
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`legal standards that have been provided to me by TQ Delta’s attorneys.
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`25. Anticipation: It is my understanding that a patent is invalid as
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`anticipated if each and every limitation of the claimed invention is disclosed in a
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`single prior art reference, either expressly or inherently, such that one of ordinary
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`skill in the art would be enabled to make the claimed invention without undue
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`experimentation. For anticipation, every limitation of a claim must appear in a
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`single prior art reference as arranged in the claim. An anticipating reference must
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`describe the patented subject matter with clarity and detail to establish that the
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`subject matter existed in the prior art and that such existence would be recognized
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`by one of ordinary skill. The prior art is enabling if the disclosure would have put
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`the public in possession (i.e., provided knowledge) of the claimed invention and
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`would have enabled one of ordinary skill to make or carry out the invention
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`without undue experimentation.
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`26.
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`Inherency: I understand that if a prior art reference does not
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`expressly disclose a claimed feature, but the teaching of the reference would
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`necessarily result in a product with the claimed feature, then anticipation may be
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`met inherently. For a prior art reference to inherently disclose a claimed feature,
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`however, the feature must be necessarily present and may not be established just
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`because it may be probable or possible. The mere fact that a condition may result
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`from a set of circumstances, or even probably results from the set of
`
`circumstances, is not sufficient for proof of inherency. Further, I understand that
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`for the purposes of evaluating anticipation of a prior art reference, the reference
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`must be interpreted from the understanding of one of ordinary skill in the art.
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`27. Obviousness in General: I have been informed that a patent can also
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`be invalidated through obviousness if the subject matter of a claim as a whole
`
`would have been obvious at the time of the invention to a person of ordinary skill
`
`in the art. I understand that obviousness allows for the combination of prior art
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`references. I have been informed that there are three basic inquiries that must be
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`considered for obviousness:
`
`a. What is the scope and content of the prior art?
`
`b. What are the differences, if any, between the prior art and each claim
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`of the patent?
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`c. What is the level of ordinary skill in the art at the time the invention
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`of the patent was made?
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`28.
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`I also understand that when prior art references require selective
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`combination to render a patent obvious, there must be some reason to combine the
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`references other than hindsight. Even if there would have been an apparent reason
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`for combining prior art references, however, there must also have been a
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`reasonable expectation of success. I understand that features from prior art
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`references need not be physically combinable (i.e., a combination may be obvious
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`if one of ordinary skill in the art would know how to make any necessary
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`modifications to combine features from prior art references), but that this concept
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`does not negate the requirement of a reasonable expectation of success. One must
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`also consider the evidence from secondary considerations including commercial
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`success, copying, long-felt but unresolved needs, failure of others to solve the
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`problem, unexpected results, and whether the invention was made independently
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`by others at the same time of the invention. I understand that these secondary
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`considerations can overcome a finding of obviousness.
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`D. Claim Construction
`
`29.
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`I have applied the claim constructions that the Board adopted in its
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`Institution decision in arriving at my opinions, with one exception where the
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`Board in my opinion adopted an incorrect construction offered by Cisco. To the
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`extent that the Board did not construe a claim term, I applied the plain and
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`ordinary meaning of the term to a person of ordinary skill in the art.
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`30. Specifically, the Board construed the term “array,” as “an ordered
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`collection of multiple data items of the same type.” “Transceiver” was construed
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`as “a device, such as a modem, with a transmitter and receiver.” I do not
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`specifically agree or disagree with these constructions, as they do not matter in
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`resolving any of the disputes in these proceedings. The Board also construed the
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`term “frequency domain received idle channel noise information” to mean
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`“information about the background noise present in each of a plurality of
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`frequency subchannels when the subchannels are not in use.” I do not agree that
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`this is the correct construction, but for purposes of this IPR there is no dispute
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`over the dispositive aspects of this construction.”3
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`31. Cisco proposes that “during Showtime” should be construed as
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`“during normal communications of an ANSI T1.413 compliant device.” To the
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`extent Cisco’s construction and the Board’s interpretation for “during Showtime”
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`purports to include modem initialization and training as part of “normal
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`communication,” Cisco’s proposed construction is incorrect. It is well accepted in
`                                                            
`3 In my opinion, the correct construction is an “ordered set of values representative of noise in
`the frequency domain measured on respective subchannels while no input signals are being
`transmitted on the subchannels.” This is similar to the construction adopted by the District Court
`in related litigation, which is an “ordered set of values representative of noise in the frequency
`domain that was received by a transceiver on respective subchannels in the absence of a
`transmission signal.”
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`the art that “Showtime” does not include any modem initialization or modem
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`training. See U.S. Pat. Pub. No. 20050190826 at ¶ 6 (“[i]nitialization (aka
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`training) is the state or time period immediately preceding “Showtime,” during
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`which signals are exchanged between the modems in order to prepare showtime,
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`but in which no user data are being communicated”). Dr. Kiaei agreed that
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`“Showtime” is a term of art that is “used to refer to the mode that follows the
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`completion of initialization and handshake equipment….” See, e.g., 1007 IPR Ex.
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`1009, Kiaei Decl. at ¶ 43. In addition, neither the concept of “Showtime” nor the
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`claims of the ’956 patent are limited to an “ANSI T1.413 compliant device.”
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`Even as of the priority date of the ’430 patent in 2000, “Showtime” was a concept
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`that was also used in connection with the ITU-T G.992.1 and G.992.2 DSL
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`communications standards, and its definition was—and still is—not specific to
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`any one DSL standard. For example, ITU-T G.992.1 states that “Showtime” is a
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`“state of either ATU-C or ATU-R – reached after all initialization and training is
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`completed – in which user data is transmitted.” ITU-T G.992.1 (06/99), § 3.28.
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`Further, the challenged ’956 patent claims recite a transceiver “capable of
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`transmitting diagnostic
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`information over a communication channel using
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`multicarrier modulation,” which is not just an ANSI T1.413 compliant transceiver.
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`Dr. Kiaei showed at his deposition that he was importing the example of an ANSI
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`T1.413 compliant device from the ’956 specification into the claims, which I
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`understand to be improper under the law for claim construction. See Kiaei Dep.
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`Tr. at 67:10-18, 68:7-11, 68:18-69:15, 70:21-72:6. In light of the foregoing, a
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`person of ordinary signal in the art would have understood “During Showtime” to
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`mean “during normal data communication that occurs after initialization.”
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`32.
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`I also understand that Cisco’s Expert, Dr. Kiaei, has effectively
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`offered a construction for the terms “channel” and “subchannel.” See e.g., 1007
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`IPR Kiaei Decl. at ¶¶ 56–59. In view of the Diagnostic Mode Patents, I
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`understand Dr. Kiaei’s construction of “subchannel” to be overly broad. As I
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`previously stated at Section III.A, the Diagnostic Mode Patents are directed, in
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`part, to the exchange of diagnostic and test information between transceivers, such
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`as ADSL transceivers. See, e.g., ’956 patent at 1:32–35. The Diagnostic Mode
`
`Patents explain that communication between ADSL transceivers “is accomplished
`
`by modulating the data to be transmitted onto a multiplicity of discrete frequency
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`carriers which are summed together and then transmitted over the subscriber loop.
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`Individually,
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`the carriers
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`form discrete, non-overlapping communication
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`subchannels of limited bandwidth.” ’956 patent, 1:44–47. Thus, based on the
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`disclosure of the Diagnostic Mode Patents, I understand that each of these
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`individual carriers is a subchannel. The Diagnostic Mode Patents explain that
`
`“[c]ollectively, the carriers form what is effectively a broadband communications
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`channel.” ’956 patent, 1:47–50. The broadband communications channel
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`comprising the individual carriers constitutes the multicarrier communication
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`channel recited in the claims. See e.g., ’956 patent, Claim 1. The data is
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`modulated on the subchannels of a multicarrier communication channel using a
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`multicarrier modulation scheme such as DMT or OFDM (“Orthogonal Frequency
`
`Division Multiplexing”). Thus, in the context of the Diagnostic Mode Patent, I
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`understand the term “subchannel” recited in the claims to mean “a carrier of a
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`multicarrier communication channel.”
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`IV. OPINIONS
`
`A. Level of Ordinary Skill in the Art
`
`33.
`
`I understand that a person of ordinary skill in the art is considered to
`
`have the normal skills and knowledge of a person in a certain technical field, as of
`
`the time of the invention at issue. I understand that factors that may be considered
`
`in determining the level of ordinary skill in the art include: (1) the education level
`
`of the inventor; (2) the types of problems encountered in the art; (3) the prior art
`
`solutions to those problems; (4) the rapidity with which innovations are made; (5)
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`the sophistication of the technology; and (6) the education level of active workers
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`in the field.
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`34. With respect to Diagnostic Mode Patents, a person of ordinary skill in
`
`the art would have an electrical engineering background and experience in the
`
`design of multicarrier communication systems, such as those employing OFDM or
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`DMT modulation. More particularly, a person of skill in the art would be a person
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`with a bachelor’s degree in electrical engineering (or a similar technical degree or
`
`equivalent work experience) and at least three years of experience working with
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`such multicarrier communication systems.
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`35.
`
`I have 18 years of combined industrial and academic experience in
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`the architecture, design, development, testing and production of communication
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`systems. Furthermore, I have worked directly in the field of multicarrier
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`communication systems, including product design and development, with many
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`engineers meeting the standard defined in the previous paragraph for a person of
`
`skill in the art.
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`B.
`
`Transmitting or Receiving a Test or Diagnostic Message
`Comprising “Power Level Per Subchannel Information” (Claims
`1–8 of the ‘956 Patent, claims 1–8 and 21 of the ‘412 Patent)
`
`36. For each of the claims (in each of the respective IPRs) that require
`
`transmitting or receiving a test message or diagnostic message comprising an
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`“array representing power level per subchannel information,” Cisco relies on
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`Milbrandt as disclosing this limitation.4 See, e.g., 1007 Petition at p. 24.
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`Specifically, Cisco alleges that “Milbrandt’s power spectrum density per sub-
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`frequency
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`information
`
`is representative of ‘power
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`level per subchannel
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`information.’” See, e.g.,1007 Petition at p. 24. I disagree for two reasons. First,
`
`                                                            
`4 I understand that Cisco does not contend that the other cited references disclose this claim element.  
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`Milbrandt’s sub-frequency does not correspond to the claimed “subchannel,” and
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`second, power spectrum density that is measured over Milbrandt’s “sub-
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`frequency” does not represent the claimed “power level per subchannel
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`information.”
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`(1) Milbrandt’s sub-frequency is not the claimed sub-channel
`37. Cisco alleges in each of the IPRs that Milbrandt teaches determining
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`“power spectrum density for a received signal at ‘one or more sub-frequencies over
`
`which the connection between modem 60 and 42 is established.’” See, e.g., 1007
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`Pet. at 24, citing Milbrandt at 11:38–45. Specifically, Cisco alleges that
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`“Milbrandt’s disclosure of ‘sub-frequencies,’ over which the connection between
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`modem 60 and 42
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`is established, would have been understood
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`to be
`
`‘subchannels.’” 1007 Pet at 24. I disagree. To support this allegation, Cisco relies
`
`on Dr. Kiaei’s assertion equating Milbrandt’s “sub-frequency” and the claimed
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`“subchannels” to an ANSI T1.413 “frequency subcarrier.” See 1007 Kiaei Decl. at
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`p. 55 (“A POSITA would have recognized that the term “frequency sub-carrier” in
`
`the ANSI T1.413 standard corresponds to Milbrandt’s “sub-frequency,” and that
`
`both of these terms correspond to the claimed “subchannel.”). I disagree.
`
`Milbrandt’s “sub-frequency” is not the claimed “subchannel” or the ANSI T1.413
`
`“frequency subcarrier.”
`
`38. As I explained in the Claim Construction of this Declaration, the
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`claimed “subchannels” in each of the Diagnostic Mode patents are the smallest
`
`discrete divisions, i.e., carriers, of the multicarrier communication channel that are
`
`modulated using multicarrier modulation. See , e.g., ’956 patent 1:42–51
`
`(“Individually,
`
`the carriers form discrete, non-overlapping communication
`
`subchannels of limited bandwidth. Collectively, the carriers form what is
`
`effectively a broadband communication channel.”). For example, ADSL1 and
`
`ADSL2 have 256 subchannels, ADSL2+ has 512 subchannels and VDSL2 has
`
`4096 subchannels (for the 17 MHz profile).
`
`39.
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`In ADSL1 and ADSL2, the upstream band comprises subchannels in
`
`the 25–138 kHz range and is used for upstream communications, i.e., from the
`
`subscriber site modem to the central office modem; the downstream band
`
`comprises subchannels in the 138–1104 kHz range and is used for downstream
`
`communications, i.e., from the central office modem to the subscriber site modem.
`
`Typically, no subcarriers in the 0–25 kHz frequency range are used for data
`
`transmission, since this frequency range is reserved for plain old telephone service
`
`(“POTS”) and a “guard band” between POTS frequencies and ADSL upstream
`
`frequencies so that the latter do not interfere with simultaneous POTS phone calls
`
`on the line. See ANSI T1.413 at § 6.12 and Figure 17; ANSI T1.413-1998 at §
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`6.14 and Figure 27.
`
`40. The Milbrandt patent provides evidence that the inventor is using the
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`terms “sub-frequency” and “subchannel” to refer to different things. First,
`
`Milbrandt refers to dividing the ADSL spectrum into “sub-frequencies” for
`
`downstream and upstream transmission, but refers to “sub-channels” when
`
`discussing DMT multicarrier units. See Milbrandt at 11:2–9. He does not
`
`describe these terms to be the same thing. Based on Milbrandt’s use of the term
`
`“sub-frequency,” one of ordinary skill in the art would conclude that the term
`
`refers to the upstream or downstream frequency bands in ADSL or to the
`
`frequency bands used for communication protocols other than ADSL (such as
`
`VDSL, SDSL or the voice spectrum protocols such as V.90.) See Milbrandt at
`
`12:9–15 (“sub-frequency of communication, such as frequencies supported by
`
`subscriber line 16 for downlink or uplink transmission of data”). Thus, in contrast
`
`to the Diagnostic Mode Patents that define an individual “subchannel” as a portion
`
`of a larger multicarrier communication channel or band, Milbrandt’s “sub-
`
`frequency” is an independent channel or band. Compare Milbrandt at 11:4–5
`
`(“[e]ach sub-frequency is an independent channel and supports transmission of its
`
`own stream of data signals”) with’956 patent at 1:42–51 (“Individually, the
`
`carriers form discrete, non-overlapping communication subchannels of limited
`
`bandwidth. Collectively, the carriers form what is effectively a broadband
`
`communication channel.”).
`
`41. Second, Milbrandt teaches that there is at least one sub-frequency in
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`the voice frequency spectrum
`
`that
`
`is capable of supporting
`
`the V.90
`
`communication protocol. See Milbrandt at 11:50–53 (describing communication
`
`“over any achievable range of sub-frequencies using any suitable communication
`
`protocols, such as, for example, over a sub-frequency in the voice frequency
`
`spectrum using the V.90 communication protocol”).   This teaching alone from
`
`Milbrandt informs a person of skill in the art that Milbrandt’s “sub-frequency” is
`
`not the same as an ANSI T.413 compliant subchannel—and is also therefore not
`
`the claimed “subchannel”—for the following reason: there is no ANSI T.413
`
`ADSL subchannel in the voice frequency spectrum capable of supporting the V.90
`
`protocol. See Milbrandt at 11:35–36, 11:50–53 and 13:9–11. ADSL’s lowest
`
`subcarriers are centered at 0 Hz (which is not used) and 4312.5 Hz, and neither of
`
`these alone nor in combination can support the V.90 communication protocol
`
`because the V.90 protocol is fundamentally different from ADSL and uses the 0–4
`
`kHz voice band without partitioning it into subchannels. See V.90 at p. 41
`
`(Appendix 1 Overview). Therefore, Milbrandt’s sub-frequency does not refer to
`
`an ANSI T1.413 “frequency subcarrier” or multicarrier subchannel. 
`
`42. Furthermore,
`
`the
`
`invention disclosed
`
`in Milbrandt
`
`includes
`
`determining the appropriate communication protocol for providing data services
`
`based on measured parameters for the different sub-frequencies, corresponding to
`
`the respective communication protocols. See Milbrandt at 15:2–5 (“[s]erver 18
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`20
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`determines the communication protocol that is best adapted to provide the
`
`determined transmit power spectrum density of modem 60 or 42 for the frequency
`
`spectrum supported by subscriber line 16”). Milbrandt discloses that the modems
`
`support many different communication protocols, such as “any suitable digital
`
`subscriber
`
`line
`
`technology (xDSL), referred
`
`to generally as an XDSL
`
`communication protocol” as well as “Ethernet; fast Ethernet; V-series data
`
`protocols such as V.32bis, V.32terbo, V.34, V.42, V.42bis, and V.90.” Id. at 4:66–
`
`5:3 et. seq.
`
`43. To determine the best communication protocol based on the transmit
`
`power spectrum density, Milbrandt discloses computing the power spectrum
`
`density and attenuation information for sub-frequencies corresponding to the
`
`communication protocols, e.g. 0 kHz to 128 kHz, or 129 kHz to 1.1 MHz, for
`
`xDSL.