IN THE UNITED STATES PATENT AND TRADEMARK OFFICE
`
`
`Yeong Hyeon Kwon, et al.
`In re Patent of:
`8,218,481 Attorney Docket No.: 00035-0010IP1
`U.S. Patent No.:
`July 10, 2012
`
`Issue Date:
`Appl. Serial No.: 12/303,947
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`Filing Date:
`July 7, 2010
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`Title:
`Method of Transmitting Data in a Mobile Communication
`System
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`Mail Stop Patent Board
`Patent Trial and Appeal Board
`U.S. Patent and Trademark Office
`P.O. Box 1450
`Alexandria, VA 22313-1450
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`DECLARATION OF JONATHAN WELLS, PH.D.
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`APPLE 1003
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`1
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`I. 
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`II. 
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`Table of Contents
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`Introduction ...................................................................................................... 4 
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`Qualifications ................................................................................................... 4 
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`III.  Materials Considered ....................................................................................... 7 
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`IV.  Applicable Legal Standards ............................................................................. 9 
`
`A.  My Understanding of Anticipation ....................................................... 9 
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`B.  My Understanding of Obviousness ..................................................... 10 
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`C.  My Understanding of Claim Construction .......................................... 14 
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`V. 
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`Level of Ordinary Skill in the Art ................................................................. 15 
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`VI.  Overview of the Technology ......................................................................... 16 
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`A. 
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`Random Access Overview .................................................................. 16 
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`1. 
`
`Introduction ............................................................................... 16 
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`2.  When is Random Access Used? ............................................... 19 
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`3. 
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`4. 
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`Types of Random Access Procedures ....................................... 20 
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`The Random Access Preamble ................................................. 21 
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`B. 
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`Preamble Code Sequences .................................................................. 23 
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`1. 
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`2. 
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`Hadamard Code Sequences ....................................................... 25 
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`CAZAC Sequences ................................................................... 26 
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`Zadoff–Chu Sequences ................................................... 27 
`a) 
`GCL Sequences .............................................................. 28 
`b) 
`3.  Manipulation of Code Sequences ............................................. 28 
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`VII.  Brief Overview of the ‘481 Patent ................................................................. 31 
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`VIII.  Claim Construction ........................................................................................ 34 
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`IX.  Application of IEEE802.16-2004 to the Challenged Claims of the ‘481
`Patent ............................................................................................................. 45 
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`A. 
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`B. 
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`C. 
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`D. 
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`Preamble structure (Claims 1 and 8) ................................................... 46 
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`Transmitting/transmitter configured to transmit, on a random access
`channel, said preamble sequence (Claims 1 and 8) ............................ 49 
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`An N-th sequence (Claims 15 and 16) ................................................ 52 
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`CP is identical to a rear part of said N-th sequence (Claims 15 and 16)
` ............................................................................................................. 52 
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`X.  Application of IEEE802.16-2004 and Chou to the Challenged Claims of the
`‘481 Patent ..................................................................................................... 55 
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`A. 
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`Preamble generation unit (Claim 8) .................................................... 55 
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`XI.  Application of IEEE802.16-2004 and Tan to the Challenged Claims of the
`‘481 Patent ..................................................................................................... 61 
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`A. 
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`B. 
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`C. 
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`CAZAC sequence (Claims 2 and 9) .................................................... 61 
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`Cyclic shift (Claims 3 and 10) ............................................................. 65 
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`Value of cyclic shift being an integer multiple of a predetermined
`circular shift unit (Claims 4 and 11) ................................................... 70 
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`D.  Applying said cyclic shift comprises multiplying said specific se-
`quence by an exponential sequence (Claims 6 and 13) ...................... 72 
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`XII.  Application of IEEE802.16e-2004, Chou and Tan to the Challenged Claims
`of the ‘481 Patent ........................................................................................... 74 
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`XIII.  Application of IEEE802.16e-2005 and IEEE802.16-2004 to the Challenged
`Claims of the ‘481 Patent .............................................................................. 75 
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`XIV.  Application of IEEE802.16e-2005, IEEE802.16-2004 and Chou to the
`Challenged Claims of the ‘481 Patent ........................................................... 80 
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`XV.  Application of IEEE802.16e-2005, IEEE802.16-2004 and Tan to the
`Challenged Claims of the ‘481 Patent ........................................................... 81 
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`XVI.  Application of IEEE802.16e-2005, IEEE802.16-2004, Chou and Tan to the
`Challenged Claims of the ‘481 Patent ........................................................... 82 
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`XVII. Conclusions .................................................................................................... 83 
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`4
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`I.
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`Introduction
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`I, Dr. Jonathan Wells, declare as follows:
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`1.
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`I have been retained on behalf of Petitioner (Apple Inc., Microsoft
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`Corporation, Microsoft Mobile Oy, and Microsoft Mobile Inc. (f/k/a Nokia Inc.) to
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`provide expert opinions in connection with this inter partes review. Specifically, I
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`have been asked to provide my opinion relating to an inquiry into the patentability
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`of claims of the U.S. Patent No. 8,218,481 (the “‘481 patent”).
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`II. Qualifications
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`2.
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`I have over 25 years of academic and industry experience in wireless
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`networks (e.g., 2G, 3G and 4G networks, comprising GSM, EDGE, WCDMA,
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`HSDPA and LTE technologies), cellular infrastructure equipment (base stations,
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`backhaul and handsets), and wireless standards, rules and regulations (e.g., 3GPP,
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`FCC, ETSI and CEPT). Over my career, I have worked with companies to develop
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`and deploy radio frequency (RF) hardware for telecommunication infrastructure
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`equipment for worldwide export, to implement marketing and product develop-
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`ment strategies for cellular wireless products, and to participate in Federal Com-
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`munications Commission (“FCC”), European Conference of Postal and Telecom-
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`munications Administrations (“CEPT”), European Telecommunications Standards
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`Institute (“ETSI”) and other technical body meetings.
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`3.
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`In 1987, I received my Bachelor of Science degree in Physics with
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`Physical Electronics (with 1st Class Honours) from the University of Bath, Bath,
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`United Kingdom. In 1991, I received the Doctor of Philosophy (Ph.D.) degree in
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`Physics from the University of Bath. In 1998, I received a Master of Business Ad-
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`ministration (with distinction) from Massey University, New Zealand.
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`4.
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`After completing my Ph.D., I began working at the University of Bath
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`as a Postdoctoral Research Officer. I continued to work at the University of Bath
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`until 1992. During this time, I built novel electronic devices, and developed soft-
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`ware models to predict their performance in wireless communication systems.
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`5.
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` For more than 20 years I worked in private industry designing, devel-
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`oping and implementing various wireless communication products throughout the
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`world.
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`6.
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`Specifically, from 1993 to 1994, I was a Senior Design Engineer at
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`Matra Marconi Space, where I developed space-qualified electronic components
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`and sub-systems for two satellite systems.
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`7.
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`From 1994 to 1995, I was a Senior RF Design Engineer, and from
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`1995-1998, I was RF Group Manager, at MAS Technology (now Aviat Networks),
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`where I, among other things, led the development of three families of innovative
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`wireless products, oversaw the company’s European regulatory approvals, and per-
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`sonally designed a wide range of RF devices.
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`8.
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`From 1998 to 1999, I was an Engineering Group Leader, and from
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`1999-2000 I was the Director of Wideband Products, at Adaptive Broadband (now
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`GE Digital Energy), where I oversaw the Terrestrial Infrastructure Group, and led
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`the development of a family of digital radio products.
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`9.
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`From 2000 to 2004, I was the Director of Product Development at
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`Stratex Networks (now Aviat Networks), where I was responsible for the global
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`product development of the company’s Outdoor Unit (ODU) portfolio of high-end
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`digital microwave radios, which were primarily directed towards cellular applica-
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`tions.
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`10. From 2005 to 2007, I was the Director of Product Management and
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`Global Regulatory Affairs at GigaBeam Corporation, where I developed the over-
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`all product strategy for a wideband communication system for future cellular ap-
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`plications. During this time I had responsibility for establishing a global regulatory
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`framework for this new product, which included developing FCC (Federal Com-
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`munications Commission) and ETSI (European Telecommunications Standards In-
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`stitute) standards to cover the specification and regulation of the system.
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`11. Since 2007, I have been the Managing Partner of AJIS Consulting––
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`an independent consulting firm specializing in wireless communications and
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`emerging wireless fields. Specifically, I analyze cellular and wireless technologies,
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`as well as conduct technical workshops on various wireless technologies; including
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`cellular networks, mm-wave radios, security sensors and short range radios.
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`12.
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`I have given guest lectures on various aspects of technology at UC
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`Berkeley and Carnegie Mellon University. I have authored or co-authored more
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`than 40 scientific and industry publications relating to wireless networks, cellular
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`infrastructure equipment, and wireless standards, rules and regulations. I also pub-
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`lished a book titled “Multi-Gigabit Microwave and Millimeter-Wave Wireless
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`Communications” in 2010. I have presented numerous tutorials, workshops, and
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`lectures to industry and academic audiences on these topics. I am listed as the lead
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`inventor on multiple patents that relate to these topics as well. I was elected a Sen-
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`ior Member of the Institute of Electrical and Electronic Engineers (IEEE) in 1999.
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`13. My Curriculum Vitae is attached as Exhibit APPL-1004, which con-
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`tains further details on my education, experience, publications, and other qualifica-
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`tions to render an expert option. My work on this case is being billed at an hourly
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`rate, with reimbursement for actual expenses. My compensation is not contingent
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`upon the outcome of this inter partes review.
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`III. Materials Considered
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`14.
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`In forming my opinions expressed in this declaration, I have consid-
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`ered and relied upon my education, background, and experience. I reviewed U.S.
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`Patent No. 8,218,481 (the “‘481 patent”, Exhibit APPL-1001) and its patent file
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`history (Exhibit APPL-1002).
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`15. Additionally, I have reviewed and relied upon the following list of
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`materials in preparation of this declaration:
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`
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`IEEE 802.16-2004 Standard, entitled “IEEE Standard for Local and Met-
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`ropolitan Area Networks Part 16: Air Interface for Fixed Broadband Wireless
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`Access Systems” (“IEEE802.16-2004,” Exhibit APPL-1005)
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`
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`IEEE 802.16e-2005 Standard, entitled “802.16e-2005 and IEEE Std
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`802.16-2004/Cor1-2005 - IEEE Standard for Local and Metropolitan Area
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`Networks Part 16: Air Interface for Fixed and Mobile Broadband Wireless Ac-
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`cess Systems Amendment 2: Physical and Medium Access Control Layers for
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`Combined Fixed and Mobile Operation in Licensed Bands and Corrigendum 1”
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`(“IEEE802.16e-2005,” Exhibit APPL-1008)
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`
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`Provisional Application No. 60/759,697 of U.S. Patent No. 8,000,305 to
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`Tan et al. (“Tan,” Exhibit APPL-1007)
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`
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`
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`U.S. Patent No. US 8,977,258 to Chou (“Chou,” Exhibit APPL-1010);
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`U.S. Patent No. US 7,417,970 to Shaheen (“Shaheen,” Exhibit APPL-
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`1011);
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`
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`U.S. Patent No. US 6,944,453 to Faerber et al. (“Faerber,” Exhibit
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`APPL-1012);
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`
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`U.S. Patent No. US 7,599,327 to Zhuang et al. (“Zhuang,” Exhibit
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`APPL-1013);
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`
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`U.S. Patent Application Publication Number 2006/0274843 to Koo et al.
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`(“Koo,” Exhibit APPL-1014)
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`
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`U.S. Patent No. US 6,374,080 to Uchida (“Uchida,” Exhibit APPL-
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`1015);
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`
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`PCT Application Publication Number WO2001041471 A1 to Bailey
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`(“Bailey,” Exhibit APPL-1016)
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`16.
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`I have also considered all other materials cited herein.
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`IV. Applicable Legal Standards
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`A. My Understanding of Anticipation
`
`A1.
`I understand that documents and materials that qualify as prior art can
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`be used to invalidate a patent claim as anticipated or as obvious.
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`A2.
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`I understand that, once the claims of a patent have been properly con-
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`strued, the second step in determining anticipation of a patent claim requires a
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`comparison of the properly construed claim language to the prior art on a limita-
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`tion-by-limitation basis.
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`A3.
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`I understand that a prior art reference “anticipates” an asserted claim,
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`and thus renders the claim invalid, if all elements of the claim are disclosed in that
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`prior art reference, either explicitly or inherently (i.e., necessarily present).
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`A4.
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`I understand that anticipation in an inter partes review must be shown
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`by a preponderance of the evidence.
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`B. My Understanding of Obviousness
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`17.
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`I understand that a patent claim is invalid if the claimed invention
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`would have been obvious to a person of ordinary skill in the field at the time of the
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`claimed invention. This means that even if all of the requirements of the claim
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`cannot be found in a single prior art reference that would anticipate the claim, the
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`claim can still be invalid.
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`18. As part of this inquiry, I have been asked to consider the level of ordi-
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`nary skill in the field that someone would have had at the time the claimed inven-
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`tion was made. In deciding the level of ordinary skill, I considered the following:
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`
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`the levels of education and experience of persons working in the field;
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`the types of problems encountered in the field; and
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`the sophistication of the technology.
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`19. To obtain a patent, a claimed invention must have, as of the priority
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`date, been nonobvious in view of the prior art in the field. I understand that an in-
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`vention is obvious when the differences between the subject matter sought to be
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`patented and the prior art are such that the subject matter as a whole would have
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`been obvious at the time of the invention to a person having ordinary skill in the
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`art.
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`20.
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`I understand that a person of ordinary skill in the art provides a refer-
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`ence point from which the prior art and claimed invention should be viewed. This
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`reference point prevents one from using his or her own insight or hindsight in de-
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`ciding whether a claim is obvious.
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`21.
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`I also understand that an obviousness determination includes the con-
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`sideration of various factors such as (1) the scope and content of the prior art, (2)
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`the differences between the prior art and the asserted claims, (3) the level of ordi-
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`nary skill in the pertinent art, and (4) the existence of secondary considerations
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`such as commercial success, long-felt but unresolved needs, failure of others, etc.
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`22.
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`I understand that an obviousness evaluation can be based on a combi-
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`nation of multiple prior art references. I understand that the prior art references
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`themselves may provide a suggestion, motivation, or reason to combine, but other
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`times the nexus linking two or more prior art references is simple common sense. I
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`further understand that obviousness analysis recognizes that market demand, rather
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`than scientific literature, often drives innovation, and that a motivation to combine
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`references may be supplied by the direction of the marketplace.
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`23.
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`I understand that if a technique has been used to improve one device,
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`and a person of ordinary skill in the art would recognize that it would improve sim-
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`ilar devices in the same way, using the technique is obvious unless its actual appli-
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`cation is beyond his or her skill.
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`24.
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`I also understand that practical and common sense considerations
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`should guide a proper obviousness analysis, because familiar items may have ob-
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`vious uses beyond their primary purposes. I further understand that a person of or-
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`dinary skill in the art looking to overcome a problem will often be able to fit to-
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`gether the teachings of multiple publications. I understand that obviousness analy-
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`sis therefore takes into account the inferences and creative steps that a person of
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`ordinary skill in the art would employ under the circumstances.
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`25.
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`I understand that a particular combination may be proven obvious by
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`showing, among other things, that it was obvious to try the combination. For ex-
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`ample, when there is a design need or market pressure to solve a problem and there
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`are a finite number of identified, predictable solutions, a person of ordinary skill
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`has good reason to pursue the known options within his or her technical grasp be-
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`cause the result is likely the product not of innovation but of ordinary skill and
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`common sense.
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`26. The combination of familiar elements according to known methods is
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`likely to be obvious when it does no more than yield predictable results. When a
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`work is available in one field of endeavor, design incentives and other market forc-
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`es can prompt variations of it, either in the same field or a different one. If a per-
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`son of ordinary skill can implement a predictable variation, the patent claim is like-
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`ly obvious.
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`27.
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`It is further my understanding that a proper obviousness analysis fo-
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`cuses on what was known or obvious to a person of ordinary skill in the art, not
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`just the patentee. Accordingly, I understand that any need or problem known in
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`the field of endeavor at the time of invention and addressed by the patent can pro-
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`vide a reason for combining the elements in the manner claimed.
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`28.
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`I understand that a claim can be obvious in light of a single reference,
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`without the need to combine references, if the elements of the claim that are not
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`found explicitly or inherently in the reference can be supplied by the common
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`sense of one of skill in the art.
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`29.
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`I understand that secondary indicia of non-obviousness may include
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`(1) a long felt but unmet need in the prior art that was satisfied by the invention of
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`the patent; (2) commercial success of processes covered by the patent; (3) unex-
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`pected results achieved by the invention; (4) praise of the invention by others
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`skilled in the art; (5) taking of licenses under the patent by others; (6) deliberate
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`copying of the invention; (7) failure of others to find a solution to the long felt
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`need; and (8) skepticism by experts. I understand that evidence of secondary indi-
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`cia of non-obviousness, if available, should be considered as part of the obvious-
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`ness analysis.
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`30.
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`I also understand that there must be a relationship between any such
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`secondary considerations and the invention. I further understand that contempora-
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`neous and independent invention by others is a secondary consideration supporting
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`an obviousness determination.
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`31.
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`In sum, my understanding is that prior art teachings are properly com-
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`bined where a person of ordinary skill in the art having the understanding and
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`knowledge reflected in the prior art and motivated by the general problem facing
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`the inventor, would have been led to make the combination of elements recited in
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`the claims. Under this analysis, the prior art references themselves, or any need or
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`problem known in the field of endeavor at the time of the invention, can provide a
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`reason for combining the elements of multiple prior art references in the claimed
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`manner.
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`32.
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`I understand that obviousness in an inter partes review must be shown
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`by a preponderance of the evidence.
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`C. My Understanding of Claim Construction
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`33.
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`I understand that, during an inter partes review, claims are to be given
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`their broadest reasonable construction in light of the specification as would be read
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`by a person of ordinary skill in the relevant art at the time of invention. For the
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`purpose of this proceeding, as discussed in greater detail below, I have used June 9,
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`2006 as the approximate time of the invention.1
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`V. Level of Ordinary Skill in the Art
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`34. A person of ordinary skill in the art (“POSA”) at or before the time of
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`the invention of the ‘481 patent2 would have had a Master’s of Science Degree in
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`an academic area emphasizing Electrical Engineering, Physics, Computer Engi-
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`neering, or an equivalent field (or a similar technical Master’s Degree, or higher
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`degree) with a concentration in wireless communication and networking systems.
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`Alternatively, a POSA would have had a Bachelor’s degree (or higher) in an aca-
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`demic area emphasizing Electrical Engineering, Physics, Computer Engineering, or
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`an equivalent field as well as at least 2 years of academic or industry experience in
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`wireless communications and networking systems. A POSA would also have had
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`1 The ‘481 patent claims priority to two Korean applications, the earliest of
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`which was filed on June 9, 2006. I have been asked to use this as the invention
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`date without acquiescence as to whether or not the ‘481 patent is actually entitled
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`to this priority date.
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`2 Unless noted otherwise, references herein to what would have been known
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`or understood by a POSA refers to the knowledge of a POSA at or before the time
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`of the purported invention of the ‘481 patent.
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`experience with the wireless Standard Setting Organizations such as ETSI, IEEE,
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`and 3GPP, and would have been familiar with relevant standards and draft stand-
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`ards directed to wireless communications. Additional education in a relevant field,
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`such as electrical engineering or physics, or industry experience may compensate
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`for a deficit in one of the other aspects of the requirements stated above. I am fa-
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`miliar with the knowledge and capabilities of one of ordinary skill in these areas
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`based on my experience working with industry, with undergraduate and post-
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`graduate students, with colleagues from academia, and with engineers practicing in
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`industry.
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`VI. Overview of the Technology
`
`A. Random Access Overview
`1.
`Introduction
`35. A mobile wireless communication system is a wireless system that
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`supports communications with mobile subscribers (e.g., mobile handsets). Sub-
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`scribers of such a system, which may include both fixed and mobile subscribers,
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`communicate via a central controller (e.g., a base station) within a communication
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`network. When individual subscribers have traffic to transmit (for example, mak-
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`ing a phone call or sending an email), the centralized controller coordinates the ac-
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`tivity.
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`36.
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`In a cellular system, there can be many subscribers who have data to
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`transmit, and need access to the shared communication channel (the time-
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`bandwidth resources available to users in that area). Such transmissions are not
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`regular, and often multiple users wish to send data simultaneously. A given proto-
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`col might make use of a centralized controller (such as a teacher in a classroom) to
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`coordinate the transmissions of different users (such as students asking questions
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`or giving answers). Such a system might be simple or complex, depending on the
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`nature of the communication, the number of users potentially wishing to access the
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`shared communications channel at the same time, and the amount of resources that
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`are available for allocation by the central controller. In a cellular system, such a
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`process is sometimes referred to as “random access.”
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`37. One of the first random access systems was a protocol called ALO-
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`HA, developed by the University of Hawaii around 1970.3 Here a satellite system
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`was used to connect remote campuses on different islands with a central campus
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`near Honolulu containing a shared, central computer. When a user at a remote
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`campus wanted to access the central computer, a radio device at the remote campus
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`3 N. Abramson, "THE ALOHA SYSTEM—Another alternative for comput-
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`er communications," Proceedings of the Fall Joint Computer Conference, pp. 281-
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`5, Nov. 1970. (Exhibit APPL-1017).
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`would transmit a message to the satellite, which would relay the signal onto a radio
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`device located at the central campus. If (and only if) the message was properly re-
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`ceived, the central campus would transmit an acknowledgement message. The
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`remote station would wait a given time for this acknowledgment. If none was re-
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`ceived, the initial access would be considered unsuccessful, and the remote termi-
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`nal would continue to retransmit the initial message until an acknowledgment was
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`successfully received.
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`38. The main reason why an acknowledgement may not be received is
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`that, in a system with many users, more than one user may be trying to access the
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`communication channel at the same time. In such a case, the multiple messages
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`may interfere, and a garbled message may be received at the central terminal,
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`which could not then issue an acknowledgement signal. To stop the retransmitted
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`messages from the multiple users from continuing to interfere with each other, the
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`retransmission protocol needs to ensure that the retransmission times from the mul-
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`tiple users are different. Thus, in the ALOHA system, retransmissions occurred
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`after a random period of time.
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`39. This is depicted in the figure below. Here user 1 communicates suc-
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`cessfully, but transmissions from users 2 and k overlap. However the retransmis-
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`sions from these two users, now at different times, do not interfere and thus both
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`successfully access the communication channel.
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`19
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`[Source: Fn. 1.]
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`40. Such a system works well in the case of a few users, where messages
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`need to be sent relatively infrequently. The basic ALOHA protocol has been ex-
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`tensively modified over the years to support more users, more efficiently, over dif-
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`ferent communications channels. Even today’s cellular systems retain some as-
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`pects of the early ALOHA systems.
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`2. When is Random Access Used?
`41. Random access is used in a cellular system whenever a user device
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`has a desire to connect to a channel in order to transmit data. Two examples of
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`when random access is required include the following:
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`42.
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`Initial access: When not in active use, a mobile device will go into a
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`low power state to conserve battery power. This is often known as an “idle” mode.
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`When data arrives to be transmitted (e.g., a user wants to make a call or send a
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`message), a phone waking up from idle mode will need to perform random access
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`to connect and resynchronize with the network. Similarly, when a mobile device is
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`first powered on, it needs to connect to and synchronize with the network, and will
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`perform random access to accomplish this.
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`43. Handover: When an active user is mobile, and travels from the cover-
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`age area of one base station to the coverage area of another, a random access pro-
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`cedure may be required to connect and synchronize to the new base station.
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`3.
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`Types of Random Access Procedures
`44. There are many different types of random access protocols and proce-
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`dures. However each of these can be categorized into two distinct forms:
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`45. Contention-based random access: In a contention-based random ac-
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`cess procedure, there is an expectation that multiple subscribers will be requesting
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`access to the communication channel at the same time, and thus collisions may oc-
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`cur. For example, during normal cellular operation, there may be many users in
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`the same area (i.e., the same cell) sending the same request to access the channel at
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`the same time, all of which may be colliding. As such, the random access proce-
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`dure will need to properly determine which of many users sent which of many re-
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`21
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`quests, in order to properly allocate resources amongst the many competing users.
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`Further, the random access procedure will need to recognize when such a collision
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`has occurred, and resolve the contention in a predictable way.
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`46. Non-contention based random access (or contention-free random ac-
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`cess): In this type of procedure, the possibility of collision for a particular user ac-
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`cessing a resource is effectively eliminated, such as by ensuring that no other user
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`will access the resource at the same time in a way that will cause such a collision.
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`An example of such a scenario may be during handover where a known user’s
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`connection is being handed over from one base station to another base station. In
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`such a controlled event, the network can inform the user of some unique identity to
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`prevent its request from colliding with requests from other users.
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`4.
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`The Random Access Preamble
`47. The random access procedure in modern cellular systems is handled
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`not by retransmission after a random delay such as in the early ALOHA systems,
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`but with an initial transmission in a known format, known as a preamble.
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`48.
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`In a practical random access procedure, a user terminal may select and
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`transmit one of a limited number of patterns or signatures called a preamble, where
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`the preamble value differentiates requests coming from different users. If two us-
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`ers happen to use the same preamble at same time then a collision occurs. Sup-
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`pose, for example, that there are 16 such patterns or signatures available for the us-
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`er to choose for the very first message of a connection procedure. If all users are
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`required to select one of the 16 preambles at random, there is only a 1/16 chance
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`that a second user will pick the same preamble. Thus the chances of the two users’
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`access requests colliding are relatively small. However if there are 16 users re-
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`questing access at the same time, there is a much higher risk of a collision because
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`there is a large amount of contention for the resource. Thus the selection of the
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`number of preambles from which user terminals can choose is a trade-off between
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`the designed capabilities of the network and implementation complexities.
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`49.
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`In a practical connection procedure, the user terminal selects one of
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`the preambles randomly. This results in the possibility of collision if the same pre-
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`amble is being used by another user terminal at the same time. Thus a contention-
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`based random access procedure is required for allocating access and resources to
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`the individual users. However, in the case of the user terminal already being con-
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`nected to the network, the network can inform the user terminal about which pre-
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`amble it should use, and thus a non-contention based procedure can be employed.
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`For example, in a handover scenario, the user terminal may already be connected
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`to one base station, and can receive from it an indication of a preamble to use when
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`connecting to a new base station.
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`50. Furthermore, the transmission of a preamble as part of the random ac-
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`cess procedure allows a number of additional benefits. For example, the preamble
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`23
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`can be repetitively transmitted to form a reference signal upon which the network
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`can perform useful channel measurements – such as, for example, estimating the
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`quality of the channel or determining the delay between the user terminal seeking
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`access and the connected base station. Additionally, the preambles themselves can
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`be used to provide additional