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`UNITED STATES PATENT AND TRADEMARK OFFICE
`_____________
`
`BEFORE THE PATENT TRIAL AND APPEAL BOARD
`_____________
`
`HTC CORPORATION, HTC AMERICA, INC.,
`and APPLE INC.,
`Petitioners,
`
`v.
`
`INVT SPE LLC,
`Patent Owner.
`_____________
`
`Case Nos. IPR2018-01555 and IPR2018-01581
`U.S. Patent No. 7,848,439
`_____________
`
`DECLARATION OF ZHI DING, PH.D. IN SUPPORT OF
`PETITIONERS’ CONSOLIDATED REPLY TO
`PATENT OWNER’S CONSOLIDATED RESPONSE
`
`
`
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`HTC Corp., HTC America, Inc. - Ex. 1016, Page 1
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`Ding Declaration re Petitioners’ Consolidated Reply
`(IPR2018-01555 and IPR2018-01581)
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`
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`INTRODUCTION
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`1. My name is Zhi Ding. I have been retained as a technical expert on
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`behalf of HTC Corporation and HTC America, Inc. to provide assistance in the
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`above-captioned matter. I understand that HTC Corporation and HTC America,
`
`Inc., along with Apple Inc., are the Petitioners in this proceeding. I have no
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`financial interest in or affiliation with the Petitioners or the Patent Owner, which I
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`understand is INVT SPE LLC. My compensation does not depend upon the
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`outcome of, or my testimony in, this inter partes review proceeding or any
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`litigation proceedings.
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`2.
`
`I have reviewed each of the following documents in this proceeding:
`
`EXHIBIT
`
`DESCRIPTION
`
`1001
`
`U.S. Patent No. 7,848,439 to She et al. (“the ’439 Patent”)
`
`1002
`
`File History of U.S. Patent No. 7,848,439 to She et al.
`
`1003
`
`U.S. Patent No. 6,904,283 to Li et al. (“Li”)
`
`1004
`
`U.S. Patent No. 7,221,680 to Vijayan et al. (“Vijayan”)
`
`1005
`
`U.S. Patent No. 6,721,569 to Hashem et al. (“Hashem”)
`
`1006
`
`U.S. Patent No. 5,596,604 to Cioffi et al. (“Cioffi”)
`
`1007
`
`Declaration of Zhi Ding, Ph.D.
`
`1008
`
`Curriculum Vitae of Zhi Ding, Ph.D.
`
`1009
`
`U.S. Patent No. 6,167,031 to Olofsson et al. (“Olofsson”)
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`-1-
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`EXHIBIT
`
`1018
`
`1019
`
`1020
`
`1021
`
`1022
`
`1023
`
`1024
`
`Ding Declaration re Petitioners’ Consolidated Reply
`(IPR2018-01555 and IPR2018-01581)
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`
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`DESCRIPTION
`
`Jacky S. Chow, Jerry C. Tu, and John M. Cioffi, A Discrete
`Multitone Transceiver System for HDSL Applications, IEEE
`JOURNAL ON SELECTED AREAS IN COMMUNICATIONS, Vol. 9, No.
`6, Pgs. 895-908 (Aug. 1991)
`
`N.M. Maslin, High data rate transmissions over h.f. links, Radio
`and Electronic Engineer, Vol. 52, No. 2, Pgs. 75-87 (Feb. 1982)
`
`Sections 6.3.10.1, 6.3.17.4 and 8.1.4.1.2.5 from the IEEE 802.16-
`2004 Standard
`
`Section 3.7 of Erik Dahlman, Stefan Parkvall, and Johan Sköld,
`4G LTE/LTE-ADVANCED FOR MOBILE BROADBAND (2011)
`
`Peter S. Chow, John M. Cioffi, and John A.C. Bingham, A
`Practical Discrete Multitone Transceiver Loading Algorithm for
`Data Transmission over Spectrally Shaped Channels, IEEE
`TRANSACTIONS ON COMMUNICATIONS, Vol. 43, No. 2/3/4, Pg. 773
`(1995)
`
`Andreas Czylwik, Adaptive OFDM for wideband radio channels,
`PROCEEDINGS OF 1996 IEEE GLOBAL TELECOMMUNICATIONS
`CONFERENCE, Vol. 1, pp. 713-718 (1996)
`
`Alexander M. Wyglinski, Fabrice Labeau, and Peter Kabal, An
`Efficient Bit Allocation Algorithm for Multicarrier Modulation,
`IEEE WIRELESS COMMUNICATIONS AND NETWORKING
`CONFERENCE, pp. 1194-1199 (2004) (Ex. 1024), at Pgs. 1194-95.
`
`2001
`
`Expert Declaration of Dr. Branimir Vojcic
`
`2002
`
`Curriculum Vitae of Dr. Branimir Vojcic
`
`2101
`
`Expert Declaration of Dr. Branimir Vojcic in Support of Patent
`Owner’s Response
`
`2102
`
`Curriculum Vitae of Dr. Branimir Vojcic
`
`
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`-2-
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`3.
`
`I understand that the application leading to U.S. Patent No. 7,848,439
`
`(“the ’439 Patent”) was U.S. Application No. 11/719,611 filed on May 17, 2007.
`
`This application was a national stage filing of PCT/JP2005/021246, filed on
`
`November 18, 2005. The PCT application claimed priority to Chinese Application
`
`No. 2004 1 0094967, filed on November 19, 2004, which I have been asked to treat
`
`as the effective filing or priority date of the ’439 Patent.
`
`QUALIFICATIONS AND PROFESSIONAL EXPERIENCE
`
`4.
`
`I presently serve as Professor in the Department of Electrical and
`
`Computer Engineering at the University of California, Davis. I have held this
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`position since my appointment on July 1, 2000. I am also a private technical
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`consultant on various technologies related to information systems. I have more
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`than three decades of research experience on a wide range of topics related to data
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`communications and signal processing.
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`5.
`
`I earned my Bachelor of Science degree in 1982, majoring in wireless
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`engineering from the Nanjing Institute of Technology (later renamed as Southeast
`
`University) in Nanjing, China. I earned my Master of Science degree in 1987 in
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`electrical engineering from the University of Toronto in Toronto, Canada. I earned
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`my Ph.D. in 1990 in electrical engineering from Cornell University in Ithaca, New
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`York.
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`6. My responsibilities as Professor at University of California, Davis,
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`include classroom instruction on various topics of communication systems and
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`signal analysis, as well as mentoring undergraduate students and supervising
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`graduate students in their research and development efforts on various topics
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`related to digital communications. I have directly supervised research and
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`development works ranging from signal transmissions and data detection to
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`wireless networking. As the chief academic advisor, I have also directly
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`supervised the completion of over 20 Masters theses and 27 Ph.D. dissertations on
`
`various topics related to digital communications and networking. I have served
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`full time as a faculty member at three major research universities in the United
`
`States over the past 29 years, including Auburn University from 1990 to 1998,
`
`University of Iowa from 1999 to 2000, and University of California, Davis, from
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`2000 to present.
`
`7.
`
`Since 1990, I have been selected as the principal investigator of
`
`multiple highly competitive federal and local research grants, including sixteen
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`major research projects supported by the National Science Foundation and two
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`research projects funded by the U.S. Army Research Office. These competitive
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`research projects focused on developing more efficient and effective digital
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`communication transceivers, networks, and signal processing tools. I have also
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`participated in several large-scale projects supported by the Defense Advanced
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`Research Projects Agency (DARPA) with teams of researchers. I have applied for,
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`and received support from, other federal, state, and industry sponsors.
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`8.
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`I have published over 190 peer-reviewed research articles in premier
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`international journals, in addition to over 230 peer-reviewed technical articles at
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`top international conferences on communications and information technologies. I
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`also authored two books on communications technologies. My most recent book,
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`co-authored with B.P. Lathi, is entitled, “Modern Digital and Analog
`
`Communication Systems,” 5th edition, and was published by the Oxford
`
`University Press in 2018. The 4th edition of this book (published in 2009) had
`
`been widely adopted as an introductory textbook to communication systems.
`
`9.
`
`In addition to the over 400 published technical papers that have been
`
`cited over 11,000 times according to Google Scholar, I am also co-inventor of 3
`
`issued U.S. patents on communication technologies.
`
`10.
`
`I am a member of the Institute of Electrical and Electronics Engineers
`
`(IEEE) and was elevated to the grade of Fellow in January 2003 for contributions
`
`made in signal processing for communication. The IEEE is the world’s largest
`
`professional society of engineers, with over 400,000 members in more than 160
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`countries. The IEEE has led the development of many standards for modern
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`digital communications and networking, most notably, the IEEE 802 series of
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`network standards. The IEEE Grade of Fellow is conferred by the Boards of
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`Directors upon a person with an extraordinary record of accomplishments in any of
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`the IEEE fields of interest. The total number selected in any one year does not
`
`exceed one-tenth of one percent of the total voting Institute membership.
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`11.
`
`I have served the IEEE in the following capacities:
`
`• Chief Information Officer of the IEEE Communications Society from
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`Jan. 2018 to present.
`
`• General Chair of the 2016 IEEE International Conference on Acoustics,
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`Speech, and Signal Processing, the flagship conference of the IEEE
`
`Signal Processing Society.
`
`• Chair of the Steering Committee for the IEEE Transactions on Wireless
`
`Communications from 2008 to 2010.
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`• Distinguished Lecturer of the IEEE Communications Society from
`
`January 2008 to December 2009.
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`• Technical Program Chair of the 2006 IEEE Globecom, one of two
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`flagship annual IEEE Communication Society conferences.
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`• Distinguished Lecturer of the IEEE Circuits and Systems Society from
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`2004 to 2005.
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`• Associate Editor of the IEEE Transactions on Signal Processing from
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`1994 to 1997 and from 2001 to 2004.
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`• Member of the IEEE Statistical Signal and Array Processing for
`
`Communications Technical Committee from 1993 to 1998.
`
`• Member of the IEEE Signal Processing for Communications Technical
`
`Committee from 1998 to 2004.
`
`12.
`
`In 2012, I received the annual Wireless Communications Technical
`
`Committee Recognition Award from the IEEE Communications Society, a peer
`
`award given to a person with a high degree of visibility and contribution in the
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`field of “Wireless and Mobile Communications Theory, Systems, and Networks.”
`
`13.
`
`I have also served as a technical consultant for the telecommunication
`
`industry. For example, in 1995 I consulted for Analog Devices, Inc. to develop the
`
`first generation DOCSIS cable modem systems. I have also consulted for other
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`companies, including Nortel Networks and NEC US Laboratories. I worked as a
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`visiting faculty research fellow at NASA Glenn Research Center in 1992 and at
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`U.S. Air Force Wright Laboratory in 1993. I have served on multiple review
`
`panels of the National Science Foundation to evaluate competitive research
`
`proposals in the field of communication. I have also reviewed a large number of
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`research proposals at the request of the National Science and Engineering Research
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`Council (NSERC) of Canada as an expert panelist from 2010 to 2013, and also at
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`the request of the Research Grant Council (RGC) of Hong Kong as an external
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`reviewer.
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`14.
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`I have served as an expert witness or consulting expert on a number of
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`matters related to intellectual property, mostly in the arena of telecommunications,
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`including cellular communications, Wi-Fi technologies, Bluetooth, and optical
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`communications. For example, since 2007, I have been engaged to work on
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`various litigations involving cellular, IEEE 802.11, and optical communication
`
`networks.
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`15. Further experience and a complete list of my publications are
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`presented in my curriculum vitae, which was previously submitted as Exhibit 1008.
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`16. Based on my above-described 3 decades of experience in
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`communications technologies, and the acceptance of my publications and
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`professional recognition by societies in my field, I believe that I am qualified to be
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`an expert in wireless communication systems, communication networks, and signal
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`processing.
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`LEGAL STANDARDS AND BACKGROUND
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`17.
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`I have been informed by counsel of several legal standards that govern
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`my analysis, including those discussed below. For example, a proper validity
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`analysis includes resolving the level of ordinary skill in the pertinent art,
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`determining the scope and content of the prior art, and ascertaining the differences
`
`between the claimed invention and the prior art. I address all of these factors in my
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`declaration below.
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`Person of Ordinary Skill in the Art
`
`18.
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`I have been advised that the claims of a patent are reviewed from the
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`perspective of a hypothetical person of ordinary skill in the art at the time of the
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`alleged invention. The “art” is the field of technology to which a patent is related.
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`I understand that the purpose of using the viewpoint of a person of ordinary skill in
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`the art (“POSITA”) is for objectivity.
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`Claim Construction
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`19.
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`It is my understanding that terms should be given their broadest
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`reasonable construction in an inter partes review proceeding. Under this standard,
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`the terms should be given their ordinary and customary meaning to a person of
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`ordinary skill in the art, unless the patent teaches a different meaning in the
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`specification.
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`20.
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`I understand that the appropriate context in which to read a claim term
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`includes both the specification and the claim language itself.
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`Validity
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`21.
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`I understand that the Petitioners bear the burden of proving the
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`instituted grounds of invalidity by a preponderance of the evidence. I understand
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`that “preponderance” means “more likely than not.” I understand that general and
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`conclusory assertions, without underlying factual evidence, may not support a
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`conclusion that something is “more likely than not.”
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`22. Rather, the “preponderance of the evidence” standard requires that a
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`reasonable finder of fact be convinced that the existence of a specific material fact
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`is more probable than the non-existence of that fact. The preponderance of the
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`evidence standard does not support speculation regarding specific facts and is
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`instead focused on whether the evidence more likely than not demonstrates the
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`existence or non-existence of specific material facts. Here, I understand that
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`Petitioners have argued that the claims at issue are rendered obvious by certain
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`prior-art references.
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`23.
`
`I have been informed that a reference may qualify as prior art to a
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`patent if the reference was known or used by others in this country, or patented or
`
`described in a printed publication in this or a foreign country, before the invention
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`by the patent holder. I have also been informed that a reference may qualify as
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`prior art to a patent if the invention was patented or described in a printed
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`publication in this or a foreign country or in public use or on sale in this country,
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`more than one year before the effective filing date of the patent. For a printed
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`publication to qualify as prior art, I understand that the Petitioner must demonstrate
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`that the publication was disseminated or otherwise sufficiently accessible to the
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`public.
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`24.
`
`I have further been informed that a reference may qualify as prior art
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`to a patent if the invention was described in a published application for a patent
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`filed in the United States before the invention by the applicant of the challenged
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`patent.
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`Obviousness
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`25.
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`I understand that a patent claim may be found unpatentable as obvious
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`if the Petitioners establish by a preponderance of the evidence that, as of the
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`priority date, the subject matter of the claim, considered as a whole, would have
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`been obvious to a person having ordinary skill in the field of the technology (the
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`“art”) to which the claimed subject matter belongs.
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`26.
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`I understand that the analysis of whether a claim is obvious depends
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`upon a number of factual inquiries, for example, (1) the scope and content of the
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`prior art; (2) the differences between the claimed subject matter and the prior art;
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`(3) the level of ordinary skill in the art; and (4) objective evidence of non-
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`obviousness.
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`27.
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`I have also been informed that the claimed invention must be
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`considered as a whole in analyzing obviousness or non-obviousness. In
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`determining the differences between the prior art and the claims, the question
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`under the obviousness inquiry is not whether the differences themselves would
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`have been obvious, but whether the claimed invention as a whole would have been
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`obvious.
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`28. Relatedly, I understand that it might be appropriate to consider
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`whether there is evidence of a “teaching, suggestion, or motivation” to combine the
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`teachings in the prior art, the nature of the problem, or the knowledge of a person
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`of ordinary skill in the art.
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`29.
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`I have been informed and understand that a prior-art reference
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`inherently discloses a limitation if the reference must necessarily function in
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`accordance with, or include, the limitation in the context of the patented
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`technology.
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`30.
`
`I understand that one indicator of non-obviousness is when prior art
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`“teaches away” from combining certain known elements. For example, a prior art
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`reference teaches away from the patent’s particular combination if it leads in a
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`different direction or discourages that combination, recommends steps that would
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`not likely lead to the patent’s result, or otherwise indicates that a seemingly
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`inoperative device would be produced.
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`31.
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`I further understand that certain objective indicia can be important
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`evidence regarding whether a patent is obvious or nonobvious, including the
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`existence of a long-felt but unsolved need, unexpected results, commercial success,
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`copying, and industry acceptance or praise.
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`STATE OF THE ART AT THE TIME THE ’439 PATENT WAS FILED
`
`Cellular Networks
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`32. As discussed in my original declaration in support of the petitions for
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`inter partes review, the ’439 Patent generally concerns technologies related to
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`wireless cellular telephones and operating such phones within a cellular network.
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`A cellular network is a wireless communication infrastructure that provides voice
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`and data services to subscribing cellular phones, also known as mobile terminals or
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`user equipment (“UE”).
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`33.
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`In a cellular network, the network coverage area is divided into many
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`cells that typically take the shape of a hexagon. Each cell is served by a base
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`station (BS), which directly communicates with the mobile terminals or user
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`equipment (UE) within the cell. In the basic cellular mode, each mobile terminal
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`communicates directly only with the serving base station. The signal flow from the
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`base station to the mobile terminal is known as the downlink (or forwardlink). The
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`signal flow from the mobile terminal to the base station is known as the uplink (or
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`reverselink).
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`34.
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`In general, many subscriber mobile terminals are served within each
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`cell by its serving base station in both the uplink and downlink directions. To
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`serve many mobile terminals simultaneously without detrimental mutual
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`interferences, the mobile terminals must follow a strict channel sharing process
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`known as multiple channel access or “multiple accesses.”
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`35. The best known multiple access schemes are frequency division
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`multiple access (FDMA), in which each mobile terminal has its own access
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`frequency band, time division multiple access (TDMA), in which each mobile
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`terminal has a unique access time slot, and code division multiple access (CDMA),
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`in which each mobile terminal has a unique access code. Before the priority date
`
`of the ’439 Patent, CDMA was the predominant technology in 3G cellular wireless
`
`standards and included two major families: UMTS and CDMA2000. In 4th
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`generation (4G) LTE networks, another multiple access technology known as
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`OFDMA (orthogonal frequency division multiple access) was proposed that would
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`jointly apply TDMA and FDMA.
`
`Orthogonal Frequency Division Multiplexing (OFDM)
`
`36. There are many ways for a wireless link to use an allocated amount of
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`bandwidth to transmit and receive data signals. Orthogonal Frequency Division
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`Multiplexing (OFDM) was one way to transmit data signals that existed before the
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`priority date of the ’439 Patent. In general, OFDM is a way to modulate digital
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`data on multiple subcarrier frequencies in a wireless network for high-speed data
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`transmission between a base station (BS) and a user equipment (UE).
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`37. With OFDM, a transmitter (such as a base station or a mobile
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`terminal) can divide its allocated frequency band into K orthogonal (non-
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`overlapping) subcarriers to simultaneously transmit K data-bearing signals in each
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`time slot. As shown in Figure 1 of the ’439 Patent (labeled “prior art”), the signal
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`bandwidth can be divided into hundreds of orthogonal subcarriers along the
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`frequency axis and a number of OFDM symbol intervals along the time axis. In
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`each subcarrier for each OFDM symbol interval, the BS can transmit a data symbol
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`to a UE.
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`HTC Corp., HTC America, Inc. - Ex. 1016, Page 17
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`Ding Declaration re Petitioners’ Consolidated Reply
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`Channel Conditions and “Adaptive Modulation and Coding”
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`38. The BS may modulate each subcarrier with data using a specific
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`modulation scheme combined with a specific coding scheme. The modulation and
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`coding schemes are chosen according to channel conditions, which can be affected
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`by phenomena such as interference and fading due to multipath propagation.
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`When the channel quality is high, higher-rate modulation and higher-rate coding
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`can be applied to achieve a higher data rate while maintaining a sufficiently low bit
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`error rate (BER). When the channel quality is poor, lower-rate modulation and
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`coding must be applied to reduce the data rate and maintain a sufficiently low bit
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`error rate.
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`39.
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`In general, the signals transmitted on different subcarriers will pass
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`through physical propagation channels to reach the intended receiver unit (mobile
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`terminal or base station). Because of pathloss, multipath effect, Doppler effect, co-
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`channel interferences, and additive channel noises, the transmitted signal quality
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`will degrade by the time it reaches the receiver. Because channel conditions on
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`different subcarriers might vary, signal qualities due to channel degradation might
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`also vary across the K subcarriers in OFDM. This phenomenon is known as
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`frequency selective fading and leads to a lower achievable data rate (channel
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`capacity) for a given channel bandwidth. This frequency selective fading problem
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`HTC Corp., HTC America, Inc. - Ex. 1016, Page 18
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`was well known before the priority date of the ’439 Patent. It was also well known
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`before the priority date of the ’439 Patent that one effective counter-measure
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`against frequency selective fading is to adjust the modulation and coding for each
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`subcarrier in response to the channel quality.
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`40.
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`In cellular systems, channel conditions vary over time because of UE
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`mobility. To compensate against time-varying channel conditions, a cellular UE
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`periodically estimates the downlink channel quality of its subcarriers. A
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`modulation and coding combination can then be chosen for each subcarrier or a
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`group of subcarriers based upon estimated channel conditions, often known as
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`channel state information (or CSI). Adjusting modulation and coding in response
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`to channel quality is known as adaptive modulation and coding (AMC). AMC was
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`mainstream technology before the priority date of the ’439 Patent.
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`OVERVIEW OF THE ’439 PATENT
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`Prior-Art Systems Alleged in the ’439 Patent
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`41. As discussed in my original declaration in support of the petitions for
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`inter partes review of the ’439 Patent, to execute AMC at the base station on a
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`subcarrier-by-subcarrier basis during downlink, channel conditions in the form of
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`channel state information (“CSI”) estimates for K subcarriers needs to be sent from
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`the mobile terminals to the base station. The value of K depends on the downlink
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`HTC Corp., HTC America, Inc. - Ex. 1016, Page 19
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`channel bandwidth and is typically in the hundreds or thousands. If the value of K
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`is too large, it was well known to people of ordinary skill in the art, before the
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`priority date of the ’439 Patent, that AMC of subcarrier granularity would require
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`too much feedback signaling overhead. It was also recognized by people of
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`ordinary skill in the art, before the priority date of the ’439 Patent, that neighboring
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`subcarriers typically experience similar channel conditions.
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`42.
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`In its background, the ’439 Patent acknowledges that, to reduce the
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`feedback overhead, multiple subcarriers can be bundled into subbands—groups of
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`multiple subcarriers in neighboring positions in the frequency domain—and that
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`this was done in the prior art. Ex. 1001, 2:12-31, 4:56-60. With AMC applied on
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`subband basis, a joint (i.e., common) modulation parameter and a joint (i.e.,
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`common) coding parameter can be applied to all of the subcarriers in a particular
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`subband. With less-granular CSI needing to be sent back from the UE to the base
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`station, the uplink spectral efficiency (i.e., spectrum utilization rate) can be
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`improved. Such AMC based on subbands was typically used before the priority
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`date of the ’439 Patent.
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`43. Figure 2 of the ’439 Patent, labeled “prior art,” helps explain AMC
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`based on subbands. In Figure 2, all of the occupied subcarriers along the
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`frequency (vertical) axis are bundled into subbands 1 through N. A single
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`HTC Corp., HTC America, Inc. - Ex. 1016, Page 20
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`(common) modulation parameter and a single (common) coding parameter are then
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`applied to all of the subcarriers in each subband, as shown by the classification
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`numbers in each coding and modulating block. Each classification number denotes
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`a specific coding parameter and a specific modulation parameter, given in Table 1
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`of the “Background Art” section of the ’439 Patent. Ex. 1001, 2:12-49.
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`FIG. 2 of ’439 Patent
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`44. Figures 3 and 4 of the ’439 Patent show an alleged prior-art system
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`implementing AMC based on subbands. As shown in Figures 4A and 4B, each
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`subband has a modulation parameter M and a coding parameter C, which are
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`applied to all of the subcarriers in the subband. Ex. 1001, 2:50-4:60.
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`HTC Corp., HTC America, Inc. - Ex. 1016, Page 21
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`Ding Declaration re Petitioners’ Consolidated Reply
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`45. On the downlink receiving side (the mobile terminal) shown in
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`Figures 3B and 4B of the ’439 Patent, a subband AMC parameter section 318
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`analyzes the condition of the OFDM subbands based on channel characteristics
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`received from a channel estimation section 319. The subband AMC parameter
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`section 318 also selects subband modulation parameters MN and coding parameters
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`CN to be sent back to the transmission side (the base station) via a feedback path
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`implemented by an uplink transmission section 320. These subband modulation
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`parameters M1 to MN and coding parameters C1 to CN are also stored by the
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`receiving side in a parameter storage section 410 so that the receiving side can later
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`use them to demodulate and decode the serial data stream sent by the transmission
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`side (at BS). Ex. 1001, 3:14-61, 4:29-55.
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`46. On the transmission side (the BS) shown in Figures 3A and 4A of the
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`’439 Patent, an AMC control section 308 controls an AMC section 301 using the
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`subband modulation parameters M1 to MN and the subband coding parameters C1
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`to CN obtained from the receiving side (the UE) via a parameter reception or
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`parameter extraction section 307. The result is a serial data stream 404 in which
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`each subband k from 1 through N has its own modulation and coding. Ex. 1001,
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`2:61-3:13, 4:1-28.
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`HTC Corp., HTC America, Inc. - Ex. 1016, Page 22
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`Ding Declaration re Petitioners’ Consolidated Reply
`(IPR2018-01555 and IPR2018-01581)
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`47. Thus, in subband-based AMC of the alleged prior art acknowledged in
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`the ’439 Patent, each UE estimates the channel conditions for its downlink
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`subbands, determines the subband AMC parameters, and feeds parameters back to
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`the BS on a subband-by-subband basis. The BS then applies the subband AMC
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`parameters to modulate and encode each downlink subband in its downlink
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`transmission to achieve an acceptable bit error rate. The ’439 Patent acknowledges
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`that such an alleged prior-art system using subband-level coding and modulation
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`reduces the difficulty of implementation and the feedback overhead of the system
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`compared to AMC based on subcarriers. Ex. 1001, 4:56-60.
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`The Purported Improvement of the ’439 Patent
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`48. The ’439 Patent alleges that prior-art systems implementing AMC
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`based on subbands still required too much feedback overhead and thus still suffer
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`from low uplink spectrum utilization rate and difficulty of adaptivity. In particular,
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`the ’439 Patent identifies a problem of “increasing spectrum utiliza