united states patent and trademark office before the ... · the real party-in-interest is ericsson...

UNITED STATES PATENT AND TRADEMARK OFFICE __________________

BEFORE THE PATENT TRIAL AND APPEAL BOARD

___________________

ERICSSON INC. AND TELEFONAKTIEBOLAGET LM ERICSSON (“Ericsson”),

Petitioner

v.

REGENTS OF THE UNIVERSITY OF MINNESOTA (“Regents”), Patent Owner

___________________

PETITION FOR INTER PARTES REVIEW

OF

U.S. PATENT NO. 8,718,185

Petition for Inter Partes Review of U.S. 8,718,185

TABLE OF CONTENTS

I. Introduction .......................................................................................................... 1

II. Mandatory Notices ............................................................................................... 3

A. Real Party-in-Interest ................................................................................. 3

B. Related Matters .......................................................................................... 3

C. Lead and Back-up Counsel and Service Information ............................... 4

III. Grounds for Standing ........................................................................................... 4

A. This Petition is Timely Under 35 U.S.C. § 315(b) .................................... 5

B. Regents Waived Sovereign Immunity by Filing Federal District Court Litigation ......................................................................................... 8

IV. Relief Requested ................................................................................................ 10

V. Technology overview ........................................................................................ 10

A. Overview of the ’185 Patent .................................................................... 10

B. Background Technology Principles ........................................................ 10

C. Person of Ordinary Skill in the Art (“POSITA”) .................................... 14

VI. Identification of Challenges and Claim Construction ....................................... 15

A. Challenged Claims ................................................................................... 15

B. Claim Construction ................................................................................... 15

1. “block(s)” ................................................................................................ 15

2. “multiple-input multiple-output (MIMO) channel” ................................... 16

C. Statutory Grounds for Challenges ........................................................... 18

D. Identification of How the Claims are Unpatentable ................................... 19


1. Challenge #1: Claims 18, 24, and 25 are unpatentable as obvious under 35 U.S.C § 103 over Baum in view of Laroia. ................................................... 19

2. Challenge #2: Claims 1, 6, 9, and 15 are unpatentable as obvious under 35 U.S.C § 103 over Baum in view of Laroia and Siew. .................................... 52

3. Challenge #3: Claim 10 is unpatentable as obvious under 35 U.S.C § 103 over Baum in view of Laroia, Siew, and Barton. ........................................... 70

VII. Conclusion ............................................................................................... 73


1

I. INTRODUCTION

Modern wireless communication technology permits large numbers of

devices to communicate while “sharing” the same electromagnetic spectrum. One

of the key enabling technologies for this “sharing” is called “orthogonal frequency

division multiplexing” (“OFDM”). OFDM was developed in the 1980s and 1990s

and is widely used today for cellular and other wireless communications.

Over the years, different techniques have been developed to improve OFDM

communications by separating the desired signal from “noise,” i.e.,

electromagnetic interference. One technique used to eliminate interference

between consecutively transmitted blocks of information is to repeat a portion of

each block. The repeated portion is commonly referred to as a “cyclic extension.”

The cyclic extension can be attached to the beginning of the OFDM signal as a

“cyclic prefix” or to the end of the of the OFDM signal as a “cyclic postfix.”

Another technique includes broadcasting signals having known values,

referred to as “training symbols” or “pilot symbols,” as well as broadcasting

signals having zero values, referred to as “null symbols” or “zero symbols.” An

OFDM receiver compares the signal actually received for each of the broadcast

training symbols and null symbols to the signal expected to be received in order to

detect and account for problems in the communication channel. The positions of

the training symbols and null symbols were sometimes changed or “hopped”


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across various time slots and frequencies to help detect and account for problems

across the entire relevant communication spectrum.

The ’185 patent applies these known techniques to a particular type of

OFDM technology called “Multiple-Input/Multiple-Output” (“MIMO”). MIMO

OFDM technology uses multiple antennas at both the transmitter and receiver of a

communication system. Because it uses multiple antennas at both communication

endpoints, MIMO has additional sources for potential communication problems

compared to having a single antenna at each end. The claims of the ’185 patent are

directed at techniques for inserting training symbols and null symbols in MIMO

OFDM communications.

The problem with the ’185 patent, however, is that all of its claimed

techniques were already known. OFDM was a relatively developed field in 2003,

and many prior art patents and publications existed discussing various aspects of

the technology, such as U.S. Patent No. 5,867,478 (“Baum”). Baum discloses the

core techniques of the ’185 patent for use in an OFDM communication system.

The remaining claimed techniques are provided by U.S. Patent No. 6,954,481

(“Laroia”), a paper by Siew regarding MIMO-OFDM systems, and U.S. Patent No.

6,449,246 (“Barton”), all of which describe various known improvements to

OFDM systems. Collectively, Baum, Laroia, Siew, and Barton render obvious all

of the challenged claims of the ’185 patent.


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Ericsson accordingly requests that the Board institute review of the

challenged claims of the ’185 patent, and find each of them unpatentable.

II. MANDATORY NOTICES

A. Real Party-in-Interest

The real party-in-interest is Ericsson Inc. and Telefonaktiebolaget LM

Ericsson (collectively “Ericsson”).

B. Related Matters

As of the filing date of this petition, the ’185 patent has been asserted in the

following cases:

Regents of the University of Minnesota v. AT&T Mobility LLC et al., MND-0-

14-cv-04666 (D.Minn. 2014);

Regents of the University of Minnesota v. Sprint Solutions, Inc. et al. MND-0-

14-cv-04669 (D.Minn. 2014);

Regents of the University of Minnesota v. T-Mobile USA, Inc. et al., MND-0-

14-cv-04671 (D.Minn. 2014); and

Regents of the University of Minnesota v. Cellco Partnership et al., MND-0-14-

cv-04672 (D.Minn. 2014).

As of the filing date of this petition, petitions for inter partes review have

been filed and are pending against patents related to the ’317 patent as follows:

IPR2017-01186 – Challenging claims of U.S. Patent No. 8,774,309


4

C. Lead and Back-up Counsel and Service Information

Lead Counsel J. Andrew Lowes Phone: (972) 680-7557 HAYNES AND BOONE, LLP Fax: (214) 200-0853 2323 Victory Ave. Suite 700 [email protected] Dallas, TX 75219 USPTO Reg. No. 40,706 Back-up Counsel

John Russell Emerson Phone: (214) 651-5328 HAYNES AND BOONE, LLP Fax: (214) 200-0853 2323 Victory Ave. Suite 700 [email protected] Dallas, TX 75219 USPTO Reg. No. 44,098

Greg Webb Phone: (972) 739-8641 HAYNES AND BOONE, LLP Fax: (214) 200-0853 2323 Victory Ave. Suite 700 [email protected] Dallas, TX 75219 USPTO Reg. No. 59,859 Clint Wilkins Phone: (972) 739-6927 HAYNES AND BOONE, LLP Fax: (214) 200-0853 2323 Victory Ave. Suite 700 [email protected] Dallas, TX 75219 USPTO Reg. No. 62,448

Please address all correspondence to lead and back-up counsel. Ericsson

also consents to electronic service by email.

III. GROUNDS FOR STANDING

Ericsson certifies that U.S. Patent No. 8,718,185 (“the ’185 patent”) is available

for inter partes review and that Ericsson is not barred or estopped from requesting

inter partes review challenging the patent claims on the grounds identified in the

petition.


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A. This Petition is Timely Under 35 U.S.C. § 315(b)

This Petition is timely filed under 35 U.S.C. § 315(b). As an initial matter,

Ericsson has not been formally served with a complaint alleging infringement of

the ’185 patent. Instead, as noted above in the related matters section, Regents

asserted the ’185 patent against 4G LTE networks operated by multiple

telecommunication carriers. The 4G LTE networks that are accused of infringing

the ’185 patent are created by the carriers through a combination of customized

equipment received from many different suppliers. Ericsson is just one of many

suppliers that sell equipment to the carriers.

Because the carriers did not adequately represent Ericsson’s interests in the

district court litigations, Ericsson filed a motion to intervene to protect its interests.

The motion to intervene was granted by the district court on March 30, 2016 and

the court ordered Ericsson’s Answer and Counterclaims, filed concurrently with its

motion, to be considered filed as of the same date. ERIC-1015, p.3.

The date Ericsson’s motion to intervene was granted, March 30, 2016,

started the one-year time period for Ericsson to timely file this Petition. In similar

circumstances, the Board has concluded that, for purposes of the one-year bar, an

amended complaint cannot be considered “served” until the corresponding motion for

leave is granted by the district court. See TRW Automotive US LLC v. Magna

Electronics, Inc., IPR2014-00293, Paper 18 at 10 (PTAB Jun. 27, 2014) (informative).


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Similarly, in the present case Ericsson cannot be considered to have been “served”

until its motion to intervene was granted by the district court. Accordingly, the one-

year bar date for Ericsson begins more than one year after March 30, 2016. Since

the present Petition was filed on or before March 30, 2017, the present Petition is

timely filed under 35 U.S.C. § 315(b).

With respect to real party-in-interest and privy considerations under 35

U.S.C. § 315(b), Ericsson is neither a real party-in-interest nor privy to the other

parties in the district court litigations. In cases where a supplier intervenes in the

district court action because its interests are not adequately represented, the Board

has found that a party who sought to intervene in a litigation was not a real party-

in-interest to a petition filed by the defendant in the litigation, in part because the

petitioner-defendant could not adequately represent the intervener’s interests, and

therefore, the parties were not closely linked. See Caterpillar Inc. v. Esco Corp.,

IPR2015-00409, Paper 9 at 13-15 (PTAB June 18, 2015). Similarly, the Board has

not found privity between an intervening supplier and the original customer

defendant. See Ericsson Inc. v. Intellectual Ventures II LLC, IPR2015-01872,

Paper 10 at 10-14 (PTAB March 14, 2016).

Given the practical situation created by the complexity of the numerous

parties and interests involved in the underlying district court litigations, the facts of

the present case do not support a finding of privity between Ericsson and other


7

defendants in the district court. As a prime example, in opposing Ericsson’s

motion to intervene, Regents initially argued that Ericsson’s (and the other

suppliers) interests could be adequately represented by the carriers. ERIC-1013,

pp.11-12. However, during oral arguments for the motion to intervene, Regents

conceded that “all these parties really have different interests. And that’s the

real problem. Everybody’s interests are a little bit different. Their

motivations are a little bit different.” ERIC-1014, Transcript pp.30-31

(statements of Regents counsel) (emphasis added).

Ultimately, after considering briefing and oral arguments on the issue, the

district court determined that Ericsson’s interests could not be adequately

represented by the carriers and allowed Ericsson to intervene so it could present

evidence and arguments related to its own products. The court also permitted two

additional equipment suppliers—Alcatel-Lucent USA, Inc. and Nokia Solutions

and Networks US LLC—to intervene to protect interests related to their products.

Because the carriers’ networks are compilations of equipment from many different

suppliers, each of which has different interests with respect to the carriers and the

other suppliers, a single equipment supplier, such as Ericsson, does not control and

cannot control the diverging interests of the other parties in this situation.

Based on the practicalities of the situation and consistent with the

determinations by the district court that the numerous parties’ interests are not


8

aligned and no one party is properly situated to adequately represent and control

the interests of the other parties, the facts of the present case do not support a

finding of privity between Ericsson and any of the other parties in the district court

litigation. Thus, the present Petition has been timely filed under 35 U.S.C.

§ 315(b).

B. Regents Waived Sovereign Immunity by Filing Federal District Court Litigation

Regents waived sovereign immunity by filing four federal district court

lawsuits against Ericsson’s customers alleging infringement of the ’185 patent.

While a panel of the Patent Trial and Appeal Board (“PTAB”) recently held that a

state university’s licensing arm was immune from inter partes review under the

Eleventh Amendment, see Covidien LP v. University of Florida Research

Foundation Inc., IPR2016-01274, Paper 21 (PTAB Jan. 25, 2017), the university

patent owner in that case had not filed federal court litigation asserting the patents-

at-issue. The PTAB in Covidien expressly stated that they did not “decide whether

the existence of a [federal district court infringement] case would effect a waiver of

sovereign immunity.” Id., 26, n. 4.

Here, Regents waived sovereign immunity by filing federal district court

lawsuits, thereby consenting to jurisdiction before the PTAB. In similar

circumstances, the Federal Circuit has held that filing patent litigation waives

sovereign immunity as to all compulsory counterclaims. Regents of Univ. of New


9

Mexico v. Knight, 321 F.3d 1111, 1126 (Fed. Cir. 2003). The Federal Circuit

based its holding on the fact that “a state as plaintiff can surely anticipate that a

defendant will have to file any compulsory counterclaims or be forever barred

from doing so” and thus “it is not unreasonable to view the state as having

consented to such counterclaims.” Id.

A petition for inter partes review is, in effect, a compulsory counterclaim, as

Congress intended these procedures to be a “complete alternative” and “complete

substitute” for a portion of invalidity arguments in district court litigation. See SAS

Institute, Inc. v. Complementsoft, LLC., 825 F.3d 1341, 1354 (Fed. Cir. 2016)

(Newman, J. dissenting). Thus, Regents has consented to jurisdiction in the PTAB

by filing lawsuits that it could “surely anticipate” would lead to invalidity claims

before the PTAB. Indeed, Regents appears to agree with this view, as it stated in a

separate proceeding, “[b]y voluntarily invoking federal jurisdiction in the

infringement litigation, the state entity could be deemed to have waived its

sovereign immunity to the IPR process.…” Reactive Surfaces Ltd. LLP v. Toyota

Motor Corp., IPR2016-01914, Paper 23 at 19-20 (PTAB March 3, 2017). That is,

Regents appears to agree with the proposition that invoking federal jurisdiction by

filing infringement litigation (as it has done in the District of Minnesota) waives

sovereign immunity in the PTAB.


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IV. RELIEF REQUESTED

Ericsson asks that the Board review the accompanying prior art and analysis,

institute a trial for inter partes review of claims 1, 6, 9, 10, 15, 18, 24, and 25 of the

’185 patent, and cancel those claims as unpatentable.

V. TECHNOLOGY OVERVIEW

A. Overview of the ’185 Patent

The ’185 patent was issued on May 6, 2014 based on a series of applications

dating back to May 21, 2003. Thus, May 21, 2003 is the earliest possible filing

date of the ’317 patent and the priority date assumed herein. The ’185 patent

relates to alleged improvements to OFDM transmissions and purports to extend

known OFDM techniques to a Multiple-Input-Multiple-Output (MIMO) OFDM

system. A detailed overview of the file history and technology presented in the

’185 patent is set forth in the testimony of Dr. Akl, ERIC-1012, ¶¶ 20-39.

B. Background Technology Principles

OFDM is a technique that can be used to transmit information in a “noisy”

or “hostile” electromagnetic environment. OFDM transmits information over an

assigned portion of the electromagnetic spectrum. The assigned spectrum is

further broken into smaller sections of the spectrum, called “subcarriers.” Each

individual subcarrier may only be able to transmit a limited amount of data, but by

combining a number of subcarriers together, an OFDM system is able to carry

large amounts of data. ERIC-1012, ¶ 20.


11

Information is transmitted over OFDM using “symbols.” Symbols are used

to turn binary numbers into sinusoidal signals that can be easily modulated onto a

carrier (or subcarrier) frequency. Symbols can be used to represent a sequence of

data bits. Barton Figures 4-8 show various examples of converting binary data into

a symbol. See ERIC-1012, ¶ 21; see also ERIC-1004. In addition to transmitting

the data symbols, OFDM systems transmit other symbols with known values,

referred to as “training symbols” or “pilot symbols,” as well as symbols having

zero values, referred to as “null symbols” or “zero symbols.” ERIC-1012, ¶ 21.

In OFDM communications, symbols are assigned a particular position in

terms of frequency (i.e. subcarrier) and time. The transmission of symbols over an

OFDM system is often represented as a grid of subcarriers and time or baud

intervals, such as shown below in Figure 1 of Baum.


12

ERIC-1003, Fig. 1. In this figure, each row represents a subcarrier. Going from

left to right along the row provides the sequence of symbols transmitted along each

subcarrier over time. The collection of symbols in a column represents the

symbols that are transmitted during a given time period or “baud interval.” ERIC-

1012, ¶ 22.

OFDM systems can be designed to account for various types of problems in

a wireless communication channel. One of these problems is “inter-symbol

interference” (“ISI”). ERIC-1001, 1:34-37. ISI occurs when two copies of the


13

same transmission are received at different times. This is often called “multipath

interference” because it occurs when a signal has two paths to a receiver, one of

which is longer than the other (i.e., just as an echo is the same sound arriving at

two different times by two different paths). Other types of problems include

“carrier frequency offset” (“CFO”), “inter-block interference” (“IBI”), “inter-

subcarrier interference” (“ICI”), and co-channel interference. ERIC-1012, ¶ 23.

OFDM engineers have developed a variety of tools for addressing these

problems. One is the use of “training symbols,” also called “pilot symbols.”

Training symbols are symbols that are “know a priori to the receiver.” ERIC-1001,

2:4-6. Training symbols permit the receiver to compare the received signal to the

expected signal for the known symbol to estimate the amount interference on the

channel. Sometimes symbols having no information (i.e., “null symbols” or “zero

symbols”) are used for the same purpose. Id., 1:59-62. Further, null symbols are

often used in estimating a carrier frequency offset between a transmitter and

receiver. ERIC-1004, 15:5–16:62; ERIC-1007, p. 1; ERIC-1012, ¶ 24.

Another technique for improving OFDM communications involves

retransmitting a portion of the signal by using a “cyclic prefix” or “cyclic

extension.” See ERIC-1001, 14:23-26; see also ERIC-1003 at 3:64-66 (“As is

known in the art, the extension is used to eliminate inter-symbol interference (ISI)


14

and inter subcarrier interference (ICI) due to multipath delay spread channels.”). A

representation of a cyclic extension is found in Baum Figure 2.

ERIC-1003, Fig. 2 (annotated); ERIC-1012, ¶ 25.

C. Person of Ordinary Skill in the Art (“POSITA”)

Ericsson submits that a POSITA in the field of the ’185 patent would have

had at least a bachelor’s degree in computer science, electrical engineering, or

computer engineering, and four years of experience with the design and/or

implementation of communication systems or equivalent. Such experience would

have led to familiarity with communication systems in general and, more

specifically, OFDM and MIMO communication systems. As such, individuals

with additional education or additional industrial experience could still be of

ordinary skill in the art if that additional aspect compensates for a deficit in one of

the other aspects of the requirements stated above. ERIC-1012, ¶¶ 16-17.

Cyclic extension inserter

Cyclic extension


15

VI. IDENTIFICATION OF CHALLENGES AND CLAIM CONSTRUCTION

A. Challenged Claims

Ericsson challenges claims 1, 6, 9, 10, 15, 18, 24, and 25 of the ’185 patent.

B. Claim Construction

This petition presents claim analysis in a manner that is consistent with the

broadest reasonable interpretation in light of the specification. See 37 C.F.R.

§ 42.100(b). Further, the claim terms are construed only to the extent necessary to

resolve the IPR. See Vivid Techs., Inc. v. Am. Sci. & Eng’g, Inc., 200 F.3d 795, 803

(Fed. Cir. 1999).

Ericsson respectfully requests that the Board construe the terms “block” and

“multiple-input multiple-output (MIMO) channel” in connection with this IPR

petition. The other terms do not appear to require construction in relation to the ’185

patent. ERIC-1012, ¶¶ 40-41.

1. “block(s)”

Ericsson requests that the Board construe the terms “block” and “blocks” to

refer to “a group of two or more.” ERIC-1012, ¶¶ 42-46.

Each of independent claims 1, 9, and 18 of the ’185 patent recite “blocks of

output symbols” and “blocks of information-bearing symbols.” See ERIC-1001,

18:20-33, 19:12-26, 20:11-25. This claim language requires each block to have


16

multiple symbols. The claims do not set a lower limit on the number of symbols in a

block, except that they must be plural.

The ’185 patent also uses the terms “block” and “blocks” in the specification,

but it does not provide an express definition. It does make clear, however, in

reference to symbols that a block constitutes more than a single symbol. Like the

claims, the specification does not set a lower limit for the term “block” either. To the

contrary, the specification refers to inserting “training symbols” inside of a block of

“information-bearing symbols” to form a “transmission block.” ERIC-1001, 2:25-27.

Similarly, the ’185 patent refers to the “[t]he nth entry of the kth block of the block of

information-bearing symbols,” implying that the term “block” has a plural number of

symbols and an arbitrary size. Id., 5:26-28; see also 7:63-66 (block of training

symbols has a “length Nb”).

Based on the requirements of the claims and these statements in the

specification, Ericsson submits that a block includes at least “a group of two or

more.” See ERIC-1012, ¶ 46.

2. “multiple-input multiple-output (MIMO) channel”

Ericsson submits that a “multiple-input multiple-output (MIMO) channel” is

“a communication channel between two or more transmit antennas and two or

more receive antennas.” ERIC-1012, ¶ 51.


17

The ’185 patent does not expressly define a MIMO channel, and the

challenged claims do not place any limitations that help to define the term.

However, the specification provides several statements that help to explain what a

MIMO channel is.

The’185 patent describes that “FIG. 1 is a block diagram illustrating a multi-

user wireless communication system 2 in which multiple transmitters

communicate with multiple receivers 6 … over multiple-input multiple-output

(MIMO) frequency-selective fading channel 8.” ERIC-1001, 4:11-19 (emphasis

added). This language identifies Figure 1 of the ’185 patent, reproduced below, as

an example of a MIMO channel.

ERIC-1001, Figure 1. The ’185 patent notes that MIMO involves “Nt transmit

antennas and Nr receive antennas.” ERIC-1001, 13:26.

Based on the above, the proper construction of “multiple-input multiple-

output (MIMO) channel” is “a communication channel between two or more

transmit antennas and two or more receive antennas.” Ericsson’s expert Dr. Akl


18

has testified that this definition is consistent with the standard usage of the term for

a POSITA in 2003. ERIC-1012, ¶¶ 47-51.

C. Statutory Grounds for Challenges

Challenge #1: Claims 18, 24, and 25 are unpatentable as obvious under 35

U.S.C § 103 over U.S. Patent No. 5,867,478 to Baum et al. (“Baum”) in view of U.S.

Patent No. 6,954,481 to Laroia et al. (“Laroia”).

Baum issued on Feb. 2, 1999. Accordingly, Baum is prior art to the ’185 patent

at least under (pre-AIA) 35 U.S.C. § 102(b).

Laroia was filed on April 18, 2000 and issued on October 11, 2005.

Accordingly, Laroia is prior art to the ’185 patent at least under (pre-AIA) 35 U.S.C.

§ 102(e).

Challenge #2: Claims 1, 6, 9, and 15 are unpatentable as obvious under 35

U.S.C § 103 over Baum in view of Laroia and further in view of “A Channel

Estimation Method for MIMO-OFDM Systems” by Siew et al. (“Siew”).

Siew was published in 2002 in connection with the London Communications

Symposium. ERIC-1016 (Declaration of John Mitchell). The paper was presented at

the Symposium on September 9, 2002. Id., ¶ 16. It was also part of the proceedings

book that was provided to attendees of the conference at that time. Id., ¶¶ 12-14.

Siew was also published on the Internet by December 2002. Id., ¶ 20; see also pp. 31-

35. Siew is thus a prior art publication at least under (pre-AIA) 35 U.S.C. § 102(a).


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Challenge #3: Claim 10 is unpatentable as obvious under 35 U.S.C § 103 over

Baum in view of Laroia and Siew and further in view of U.S. Patent No. 6,449,246 to

Barton et al. (“Barton”).

Barton was filed on December 30, 1999 and issued on September 10, 2002.

Accordingly, Barton is prior art to the ’185 patent at least under (pre-AIA) 35 U.S.C.

§§ 102(a) and 102(e).

D. Identification of How the Claims are Unpatentable

1. Challenge #1: Claims 18, 24, and 25 are unpatentable as obvious under 35 U.S.C § 103 over Baum in view of Laroia.

The combination of Baum and Laroia renders obvious claims 18, 24, and 25.

ERIC-1012, ¶¶ 146-220.

Independent Claim 18

[18.0] A method comprising:

To the extent the preamble is limiting, Baum discloses a method. Baum is

entitled “Synchronous Coherent Orthogonal Frequency Division Multiplexing

System, Method, Software, and Device.” ERIC-1003, Title (emphasis added).

Baum discloses methods for “reducing the impact of interference in OFDM

wireless communication systems.” Id., 1:7-10; ERIC-1012, ¶¶ 53-62. Thus, Baum

discloses “a method,” as recited in the preamble of claim 1. ERIC-1012, ¶¶ 146-

147.

[18.1] in a base station:


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Baum discloses “a single base unit which generates a plurality of OFDM

signals simultaneously and transmits them with sectored, distributed, or an array of

antennas.” ERIC-1003, 8:23-26 (emphasis added). Baum explains that “[t]he

transmission from a base unit to a subscriber unit is referred to as a downlink,

while the transmission from a subscriber unit to a base unit is referred to as an

uplink.” ERIC-1003, 5:65-67. Dr. Akl testifies that Baum’s “base unit” is the

same as the ’185 patent’s “base station.” ERIC-1012, ¶¶ 149-150.

[18.2] forming two or more blocks of output symbols for orthogonal frequency division multiplexing (OFDM) transmissions over a multiple-input multiple-output (MIMO) channel;

Baum discloses limitation [18.2] as follows.

Forming two or more blocks of output symbols for orthogonal frequency

division multiplexing (OFDM) transmissions: Baum is directed at a mechanism

called “Synchronous Coherent OFDM,” or SC-OFDM. ERIC-1003, 3:15-26. In

this regard, Baum forms blocks of output symbols for OFDM transmissions.

ERIC-1012, ¶¶ 151-153. Thus, Baum discloses the OFDM element of limitation

[18.2].

Baum discloses several examples of forming blocks, including Figure 12,

copied below, which shows “a frame which includes slots for data transmission.”

ERIC-1003, 2:6-9.


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Id., Fig. 12 (annotated).

Each row of the frame of Fig. 12 represents a subcarrier and each column

represents a baud interval or OFDM symbol time period. See id., 14:6-23. “Each

small square represents a symbol,” which is the smallest unit of data for

transmission. Id., 3:37-38. Baum explains that “[a] frame is a grouping of one or

more OFDM symbol time intervals and one or more subcarrier locations,” while

“[a] slot in OFDM may contain both a plurality of symbols in time and a plurality

of symbols in frequency.” Id., 8:29-30, 3:32-34. Each of the slots of Fig. 12 (e.g.,

slot 1206) “spans four baud intervals and five subcarriers, as indicated by the bold

lined boxes.” Id., 14:13-15. Baum Figure 12 discloses several such slots. Each

slot in Baum is a “block” of output symbols formed for OFDM. ERIC-1012,

Blocks (slots) of output symbols for OFDM transmissions

Block (frame) of output symbols for OFDM transmissions


22

¶¶ 151-153. Similarly, each baud interval in Baum is a “block” of output symbols

formed for OFDM.

While this Petition focuses on the slots and baud intervals of Baum as being

the claimed blocks of output symbols, each of Baum’s “frames,” “slots,” and “baud

intervals” form a group of two or more output symbols. ERIC-1003, 3:32-34

(describing slots), 8:29-49 (describing frames and baud intervals). Thus, Baum

discloses the forming blocks of output symbols element of limitation [18.2].

Over a multiple-input multiple-output (MIMO) channel: Baum discloses

transmission over a MIMO channel. As noted in the claim construction section

above, a MIMO channel is a communication channel between two or more

transmit antennas and two or more receive antennas.

Baum describes an OFDM system that “generates a plurality of OFDM

signals simultaneously and transmits them with sectored, distributed, or an array

of antennas.” ERIC-1003, 8:23-26 (emphasis added). Thus, Baum discloses a

transmitter with two or more transmit antennas. Baum also discloses a receiver

having multiple antennas. For example, Baum discloses that “in a preferred

embodiment, an SC-OFDM receiver unit with multiple antennas and receivers

uses MMSE diversity combining to combine the signals received on each

antenna.” Id., 15:47-49 (emphasis added); ERIC-1012, ¶¶ 154-156.

Based on the above, Baum discloses a MIMO communication channel


23

between two or more transmit antennas and two or more receive antennas. Thus,

Baum discloses all of the elements of limitation [18.2].

[18.3] identifying, via a hopping code and based at least on a cyclic prefix parameter, different positions within the two or more blocks of output symbols, the different positions comprising a block index value, a subcarrier index value, and the cyclic prefix parameter selected to compensate for intersymbol interference (ISI) associated with the MIMO channel;

Baum and Laroia disclose the elements of limitation [18.3].

Overview of Limitation [18.3]: Limitation [18.3] primarily concerns the

selection of positions for training symbols and for null subcarriers. These positions

are determined by a hopping code. The claim language indicates that these

positions are specified with reference to “block index value,” “subcarrier index

value,” and a “cyclic prefix parameter selected to compensate . . . .” Figure 3 of

the ’185 patent gives an example of identifying positions for null subcarriers:

ERIC-1001, Fig. 3 (annotated). In Figure 3, rows 40A, 40B, and 40C are each

“transmission blocks” having “space-time encoded information bearing symbols

Block 0

Block 1

Block 2


24

42A-C, null subcarriers 44A-44C, and training symbols 46A-46C.” ERIC-1001 at

13:45-48. Each row has a “block index value.” In Figure 3, the block index value

“k” for blocks 40A, 40B, and 40C is “k=0, k=1, and k=2 respectively.” Id., 13:40-

45. Transmission blocks 40A-40C are described as being “consecutive

transmission blocks,” meaning that 40A is transmitted before 40B, and 40B is

transmitted before 40C. Thus, each “block index value” in Figure 3 of the ’185

patent corresponds to a baud (time) interval or a group of baud intervals. ERIC-

1012, ¶¶ 157-159.

The term “subcarrier index value” is not used in the specification of the ’185

patent but it refers to the location of a subcarrier within a block. Figure 3 shows

the use of subcarrier index values, with each of the null subcarriers 44A-44C

positioned inside the blocks 40A-40C at a different relative position. This is an

example of blocks being modified according to a hopping code “so that the

position of null subcarriers 44A-44C change from block to block.” Id., 13:59-62.

In this regard, each subcarrier has an associated index value that distinguishes it

from the other subcarriers. The ’185 patent illustrates the use of subcarrier index

values when it shows the null subcarriers in different locations in Figure 3.1

Limitation [18.3] also refers to a “cyclic prefix parameter selected to

compensate for intersymbol interference (ISI) associated with the MIMO channel.”

1 The use of subcarrier index values in the ’185 patent is consistent with the use of subcarrier index values (k) in Siew. See, e.g., ERIC-1010, pp. 2-3.


25

The ’185 patent gives an example of how a cyclic prefix parameter could impact

positioning when it states that “[i]n some embodiments, training symbols 46A-46C

are inserted every N+L transmitted symbols, where a cyclic prefix of L symbols is

inserted by cyclic prefix insertion unit 19.” ERIC-1001, 13:52-56. In this

example, the number L is the cyclic prefix length. The cyclic prefix length L in the

’185 patent is an example of a cyclic prefix parameter that impacts the positioning

of null and training symbols. ERIC-1012, ¶¶ 160-161.

[identifying] . . . different positions comprising a block index value, a

subcarrier index value and the cyclic prefix parameter selected to compensate for

intersymbol interference (ISI) associated with the MIMO channel: Baum provides

a framework for identifying different output symbol positions according to “block

index value,” “subcarrier index value,” and a “cyclic prefix parameter” related to

ISI. For example, Baum teaches both the block index value and the subcarrier

index value limitations when it states that “the symbol to be transmitted on the mth

subcarrier [i.e., row m] during the nth baud interval [column n] is denoted as

x(m,n).”


26

ERIC-1003 at Fig.1, 3:43-45, FIG. 1. In this example, each baud interval “n” is a

block of data. ERIC-1012, ¶ 163. These baud intervals are transmitted

consecutively, just as blocks 40A-40C of the ’185 patent are transmitted

consecutively. ERIC-1001, 13:42-43. The “n” value in Baum is a block index

value in the same way as the “k” value in the ’185 patent discussed above. ERIC-

1012, ¶¶ 162.

The “subcarrier index value” in Baum is denoted by the letter “m.” ERIC-

1012, ¶ 162. Each subcarrier is provided with a different subcarrier index value, as

Subcarrier Index Value

“m”

Block Index Value “n”


27

shown in Baum Figure 1 and the accompanying text. ERIC-1003, 3:43-45. Fig. 2

of Baum illustrates the “block index value” and “subcarrier index value” being

used together to identify the time-frequency positions of symbols.

Baum discloses a “cyclic extension” and states that signals “will be received

with no ISI and ICI if the cyclic extension has sufficient length.” Id., 4:52-56. As

noted above for limitation [18.2], the cyclic extension in Baum is used in a MIMO

channel having multiple transmit and receive antennas. ERIC- 1012, ¶ 163.

One skilled in the art understands that a cyclic extension can come either

before or after the underlying data signal. ERIC-1012, ¶¶ 85-88. For example,

U.S. Patent No. 6,928,046 to Sajadieh et al. (“Sajadieh”), ERIC-1008, explains that

a cyclic extension, such as disclosed in Baum, “relates to the cyclical extension of

a number of bits, copied either from the end of the data frame and/or from the

beginning of the data frame, and adding the same to the opposite end of the data

frame. … Repetition of bits at the beginning of each data frame and/or at the end of

each data frame are known collectively as ‘prefix extension’ or ‘cyclic extension.’”

ERIC-1008, 2:23-42; ERIC-1012, ¶¶ 172-173.

Baum does not expressly show the use of a “cyclic prefix,” which is a cyclic

extension that is inserted at the beginning of a signal (as opposed to the end).

However, Laroia expressly discloses the use of a cyclic prefix where part of the

end of the information portion of the OFDM signal is repeated at the beginning of


28

the information portion of the OFDM signal. See, e.g., ERIC-1009, 5:17-22; see

also ERIC-1012, ¶¶ 63-67. Laroia teaches that its signal structure (including the

number of subcarriers used for the OFDM process) “depends on parameters of

the system, such as, the data rate to be supported on each individual tone and the

length of a cyclic prefix that is required to be used to ensure orthogonality in a

multipath environment.” ERIC-1009, 5:17-22 (emphasis added). The

explanation by Laroia that the cyclic prefix length is specifically selected as a

“parameter[] of the system” confirms that the length of a cyclic prefix is a

parameter that is relevant to defining the position of a symbol in an OFDM signal.

ERIC-1012, ¶ 174.

Thus, the combination of Baum and Laroia teaches identifying different

positions using a block index value, a subcarrier index value, and a cyclic prefix

parameter selected to compensate for intersymbol interference in a MIMO channel.

ERIC-1012, ¶¶ 164, 177-178.

identifying, via a hopping code and based at least on a cyclic prefix

parameter, different positions within the two or more blocks of output symbols:

Baum and Laroia teach the identification of different positions based on a hopping

code and a cyclic prefix parameter.

Baum discloses two position-selection techniques that satisfy this claim

element. First, Baum’s pilot codes are inserted at positions identified by


29

“step[ping] through the available pilot codes in a coordinated fashion.” ERIC-

1003, 11:13-17. Baum states that “[t]his coordination or allocation can be treated

as ‘code hopping’” and notes that “any techniques known in the art for

implementing orthogonal hopping patterns can be applied to the pilot code

selection process as a part of the pilot code scheme.” Id., 11:21-25; ERIC-1012,

¶¶ 165-166.

Baum provides examples of pilot codes having both constellation (training)

symbols and null symbols (i.e., null subcarriers). A pilot code set consisting of

four such pilot codes is copied below:

ERIC-1003, 12:32-39. In this example, there are four pilot codes (W1

through W4). W1 includes two training symbols (√2 and √2) and two null symbols

(0 and 0). W2 through W4 contain similar combinations of training symbols and

null subcarriers, but in different orders.2 ERIC-1012, ¶¶ 58, 167.

The process of hopping through Baum’s pilot code set results in the

selection of different positions for training symbols and null subcarriers. For

2 Note that W3 (or W4) contains a typo and that one of the -√2 entries should be a positive √2. ERIC-1012, ¶ 58


30

example, the training symbols in W1 and W2 are at different positions than they are

in W3 and W4. Similarly, the null subcarriers in W1 and W2 are at different

positions than they are in W3 and W4. Thus, Baum’s pilot code hopping process

identifies different positions for inserting the training symbols and null symbols of

the pilot code in different blocks. The pilot code hopping also determines the

block index values (n) and subcarrier index values (m) for the training and null

symbols and, as discussed above, the positioning of the symbols within the output

signal depends on the length of the cyclic extension. ERIC-1012, ¶¶ 167, 177.

Second, Baum’s pilot codes can also be inserted at positions identified by a

frequency hopping code. In frequency hopping, “the predetermined pilot codes

and data are moved from the set of predetermined frequency locations to another

set of predetermined frequency locations according to a predetermined frequency

hopping method.” ERIC- 1003 at 24:55-58. When used with the pilot codes

discussed above (e.g., (√2 √2 0 0)), this is another example of inserting the

training (constellation) symbols and null subcarriers (symbols) at positions

identified by a hopping code. ERIC-1012, ¶¶ 168-169. Baum’s frequency hopping

process identifies different positions for inserting the training symbols and null

symbols of the pilot code in different blocks. In this regard, the frequency hopping

determines the block index values (n) and subcarrier index values (m) for the

training and null symbols and, as discussed above, the positioning of the symbols


31

within the output signal depends on the length of the cyclic extension. ERIC-1012,

¶ 177.

Laroia also discloses selecting positions based on a hopping code. For

example, Laroia describes an OFDM system in which “the symbols used in the

pilots are uniquely located in a time-frequency grid, where the locations are

specified by periodic pilot tone hopping sequences.” ERIC-1009, Abstract

(emphasis added). Examples of this location-selection process are given in Figures

3 and 4 of Laroia:

ERIC-1009, Figs. 3 and 4. These figures show a time-frequency grid (similar to

the one in Baum). The marked positions (i.e., X or O) represent “pilot tones,”

which are equivalent to the training symbols of the ’185 patent and the symbols of

the pilot codes of Baum. ERIC-1009, 2:56-64. “[D]uring each symbol interval, a

distinct pilot tone is employed,” until the end of the period when the pilot tones

repeat. Id., 3:6-9. Figure 4 provides an example of hopping locations for two


32

different pilot tones (i.e., a pilot code set). Thus, Laroia discloses identifying

different positions for symbols of a pilot code in a block of output symbols based

on a hopping code. ERIC-1012, ¶¶ 63-65, 170.

As explained by Laroia “[t]he number of tones into which a certain

bandwidth can be divided into depends on parameters of the system, such as, the

data rate to be supported on each individual tone and the length of a cyclic prefix

that is required to be used to ensure orthogonality in a multipath environment.”

ERIC-1009, 5:17-22 (emphasis added). That is, Laroia teaches that the number of

subcarriers (i.e., tones) available for transmission of the pilot symbols and null

subcarriers and, therefore, the number of subcarrier positions available for the pilot

symbols and null subcarriers to hop between, is dependent on the cyclic prefix

length. In addition, the ultimate position of the pilot tones in the transmitted signal

depends on the length of the cyclic prefix because the cyclic prefix length

determines how much of the end of the signal will be repeated at the beginning of

the signal. Laroia thus discloses identifying different positions for symbols of a

pilot code in a block of output symbols based on a hopping code and based in part

on a parameter (i.e., length) of the cyclic prefix.

Thus, Baum in combination with Laroia discloses the elements of limitation

[18.3]. See ERIC-1012, ¶¶ 157-178.

[18.4] inserting, using the different positions identified via the hopping code, a first set of two or more training symbols and two or more null


33

subcarriers (i) into a first block of two or more blocks of information-bearing symbols and (ii) at a first position within the first block of information-bearing symbols;

[18.5] inserting, using the different positions identified via the hopping code, a second set of two or more training symbols and two or more null subcarriers (i) into a second block of the two or more blocks of information-bearing symbols and (ii) at a second position within the second block of information-bearing symbols, wherein the hopping code directs the first position to be different from the second position; and

The elements of [18.4] and [18.5] are substantially similar, requiring

insertion of a set of two or more training symbols and two or more null subcarriers

into a block of information-bearing symbols. The difference between [18.4] and

[18.5] is that [18.4] requires insertion into a “first block” at a “first position,”

whereas [18.5] requires insertion into a “second block” at a “second position” that

is different than the “first position.” Baum in combination with Laroia discloses

the elements of limitations [18.4] and [18.5] for the following reasons.

Training symbols: Baum discloses training symbols. In the challenged ’185

patent, the training symbols are symbols “that are known a priori to the receiver.”

ERIC-1001, 2:4-6. These training symbols are used to determine channel state

information. Id., 1:1-3. Baum discloses “pilot symbols,” which are “known”

symbols that are used to “measure the channel response.” ERIC-1003, 1:20-35.

Baum explains that “known pilot symbols are periodically transmitted along with

the data symbols.” Id., 1:22-24. Baum’s “pilot symbols” are the same as the


34

training symbols disclosed by the challenged ’185 patent; they are merely called by

a different name. ERIC-1012, ¶¶ 179-180.

Baum also uses “pilot codes” to measure channel interference. ERIC-1003,

4:62-65. A “pilot code” is an ordered collection (or “vector”) of symbols. Id., 7:7-

8. Baum discloses the use of pilot codes “rather than individual pilot symbols.”

Id., 5:24-27. These pilot codes are known by Baum’s receiving unit. Id., 12:44-

50. “To estimate the channel response,” Baum’s “receiver correlates a composite

pilot code portion of a received slot with a known, stored pilot code.” Id., 15:3-6.

Thus, Baum’s pilot codes include training symbols. ERIC-1012, ¶¶ 136-137.

Null Subcarriers: Baum discloses the use of “null subcarriers.” In the ’185

patent, “null subcarriers” are also called “zero symbols.” See ERIC-1001, 2:29-34.

Baum describes this same concept as a “null symbol,” which are “symbols with a

constellation value of (0,0).” Id., 9:44-48; ERIC-1012, ¶ 136-137. Baum’s “null

symbols” are the same as the “null subcarriers” disclosed by the challenged ’185

patent. ERIC-1012, ¶ 137.

inserting, using the different positions identified via the hopping code, a first

(second) set of two or more training symbols and two or more null subcarriers (i)

into a first (second) block of the two or more blocks of information-bearing

symbols and (ii) at a first (second) position within the first (second) block of

information-bearing symbols:


35

As discussed above with respect to [18.3], Baum and Laroia disclose

identifying different positions for inserting symbols of a pilot code in a block of

output symbols based on a hopping code and based in part on a parameter (i.e.,

length) of the cyclic prefix. Baum and Laroia further disclose inserting two

training symbols (i.e. constellation symbols) and two null subcarriers (i.e., null

symbols) at the identified positions within two or more information-bearing

symbols.

In particular, as noted above, Baum discloses the use of pilot codes having

two constellation (training) symbols and two null symbols (i.e., null subcarriers),

such as the following pilot code set:

Id., 12:32-39. When the pilot code includes at least two constellation symbols and

at least two null symbols and is inserted at the positions identified in [18.3], then

this claim element is satisfied. ERIC-1012, ¶¶ 181-185.

In this regard, Dr. Akl provides several diagrams (reproduced below)

showing the insertion of training symbols and null subcarriers at the positions

identified by a hopping code and based on a cyclic prefix length in accordance

with the disclosures of Baum and Laroia as discussed above with respect to [18.3].


36

For example, Dr. Akl has testified that for a system with two transmit antennas, the

use of orthogonal pilot codes and pilot code hopping (as taught by Baum) with

sloped frequency hopping (as taught by Laroia) would result in time-frequency

grids as follows:

ERIC-1012, ¶¶ 189-191, 195-196. These diagrams show pilot code hopping,

multiple antennas, and pilot codes having two training symbols and two null

subcarriers as claimed. Id.

Antenna 1: Antenna 2:

Time (OFDM symbols)

Fre

quen

cy

(Sub

carr

iers

)

Time (OFDM symbols)

Fre

quen

cy

(Sub

carr

iers

)

A combination of pilot code hopping and frequency hopping based on FIG. 7 of Baum and Fig. 3 of

Laroia


37

wherein the hopping code directs the first position to be different from the second

position:

As shown in the time-frequency grids, the positions for the sets of the two or

more training symbols and two or more null subcarriers is different and changes

across the groups of two or more information-bearing symbols. For example, as

shown in the annotated version below, the positions of the training symbols and

null subcarriers within the group of symbols for antenna 1 are different from the

positions of the training symbols and null subcarriers within the group of symbols

for antenna 2.


38

As another example of the different positions, for each antenna the positions

of the training symbols and null subcarriers within the group of symbols in the

second baud interval are different from the positions of the training symbols and

null subcarriers within the group of symbols in the third, fourth, and fifth baud

intervals as shown in the annotated version below.


Time (OFDM symbols)

Fre

quen

cy

(Sub

carr

iers

)

Time (OFDM symbols)

Fre

quen

cy

(Sub

carr

iers

)

A combination of pilot code hopping and frequency hopping based on FIG. 7 of Baum and Fig. 3 of Laroia

annotated to emphasize different positions between antennas

Second set of training

symbols and null

subcarriers at a second,

different position in a second block

First set of training

symbols and null

subcarriers at a first

position in a first block


39

As yet another example of the different positions, if a slot structure is

utilized as disclosed in Baum (e.g., consisting of 4 baud intervals and 5 subcarriers

as shown in Fig. 12 of Baum), then the positions of the training symbols and null

subcarriers within the group of symbols of a slot are different from (1) the

positions of the training symbols and null subcarriers within the group of symbols

in other slots of the same antenna as well as (2) the positions of the training


Time (OFDM symbols)

Fre

quen

cy

(Sub

carr

iers

)

Time (OFDM symbols)

Fre

quen

cy

(Sub

carr

iers

)


annotated to emphasize different positions between baud intervals of the same antenna and across antennas

Second set of training

symbols and null

subcarriers at a second,

different position in a second

block


symbols and null




symbols and null




40

symbols and null subcarriers within the group of symbols in slots of the other

antenna. ERIC-1012, ¶¶ 96-97.

Dr. Akl provides similar diagrams based on frequency hopping alone (i.e.,

without pilot code hopping) and based on other distributions of the symbols of the

pilot code (e.g., based on Fig. 9 of Baum). ERIC-1012, ¶¶ 191-194, 197-199.

Each of the diagrams provided by Dr. Akl reflects implementation of a hopping

code and the relationship to the placement of the training symbols and null

subcarriers according to the combination of Baum and Laroia. These examples

show how a POSITA would have envisioned the combination of Baum and Laroia,

and confirm that the references render obvious the elements of limitations [18.4]

and [18.5].

[18.6] transmitting over the MIMO channel, via two or more antennas, transmission signals in accordance with the two or more blocks of output symbols.

Baum discloses the elements of limitation [18.6]. As noted for limitation

[18.2], Baum discloses transmitting over a MIMO channel (i.e., over a system

having multiple transmit antennas and multiple receive antennas. ERIC-1003,

Abstract, 8:23-26; ERIC-1012, ¶¶ 200-202. Baum also discloses the transmission

of transmission signals in accordance with the blocks of output symbols as formed

in accordance with [18.1]-[18.5]. See, e.g., id., Fig. 2 and Figure 12 (showing

transmission of multiple baud intervals and multiple slots). Baum’s teaching to use


41

multiple antennas to transmit signals according to the output symbol blocks (e.g.,

baud intervals, slots, etc.) satisfies the elements of limitation [18.6].

Claim 18 obviousness rationale

Combining Baum and Laroia together in the manner discussed above would

have been obvious to a POSITA for several reasons.

Reasons for combining Baum’s pilot codes, hopping codes, and MIMO

channel together: As an initial matter, it would have been obvious to a POSITA to

combine Baum’s SC-OFDM techniques with orthogonal pilot codes, hopping

codes, and a MIMO channel. As noted, a MIMO channel has two or more transmit

antennas and two or more receive antennas. The teaching of multiple transmit

antennas is disclosed by Baum as an alternative embodiment. ERIC-1003, 8:23-26

(describing an “array” of antennas). This array of antennas is specifically designed

to transmit a “plurality of OFDM signals.” Id. The use of multiple receive

antennas is taught throughout Baum. For example, Baum discloses that “[i]n a

preferred embodiment, an SC-OFDM receiver unit with multiple antennas and

receivers uses MMSE diversity combining to combine the signals received on each

antenna.” Id., 15:47-49 (emphasis added). Thus, there is an express teaching or

suggestion in Baum to use a MIMO channel with OFDM. ERIC- 1012, ¶¶ 68-70.

The use of pilot codes with SC-OFDM is also described as part of Baum’s

invention. ERIC-1003, Abstract (“the SC-OFDM signals from each SC-OFDM


42

transmitter include at least one pilot code in accordance with a predetermined pilot

code scheme”). Baum states that “SC-OFDM is based on the combination of the

following [four] elements/requirements,” the third of which is “[r]eference/pilot

signals in the transmitted OFDM signals.” ERIC-1003 at 4:32-45. Baum goes on

to say that this “third requirement can be satisfied by using pilot codes rather than

individual pilot symbols in each OFDM slot for channel response estimation.” Id.,

5:24-27. Thus, there is an express teaching in Baum suggesting using pilot codes

with Baum’s SC-OFDM technique. Further, using pilot codes with Baum’s SC-

OFDM technique is using a known technique to improve a similar method in the

same way and implementing the pilot codes would have a predictable result.

ERIC-1012, ¶¶ 71-79.

Finally, the use of hopping codes as part of an SC-OFDM system is also

taught or suggested by Baum. Baum states that code hopping is useful to

implement an SC-OFDM system in order to maintain orthogonality of the pilot

codes between different transmitters. ERIC-1003 at 11:17-29. Moreover, “any

techniques known in the art for implementing orthogonal hopping patterns can be

applied to the pilot code selection process as part of the pilot code scheme.” Id.,

11:21-25. Baum also describes an SC-OFDM system that implements frequency

hopping, which involves “predetermined pilot codes and data are moved from the

set of predetermined frequency locations to another set of predetermined frequency


43

locations according to a predetermined frequency hopping method.” ERIC-1003,

24:55-58, ERIC-1012, ¶¶ 71-79. Thus, Baum has an express teaching and

suggestion to use code hopping with an SC-OFDM system.

The combination of Baum’s SC-OFDM with a MIMO channel, pilot codes,

and hopping codes would also be obvious for additional reasons. For example, the

transmission of data from a single base station using multiple antennas results in

many of the same issues as transmitting data using multiple base stations. The

orthogonal pilot codes provide the receiving unit with information that can be used

to estimate and account for problems in the communication channel, such as

interference and/or frequency offset. ERIC-1012, ¶¶ 75-79. Use of the same

techniques would improve communications being sent from a single base station

via a plurality of antennas in the same way. Id.

The combined use of MIMO and orthogonal pilot codes is also obvious to

try in view of the limited number of antenna arrangements (single vs. multiple) and

limited number of types of training schemes (pilot symbols vs. pilot codes) that

Baum discloses for use with its SC-OFDM methods and systems. Moreover,

frequency hopping is also an obvious option to try with the multiple antennas and

orthogonal pilot codes since it allows for better detection of interference, poor

channel conditions, or other frequency-dependent factors. ERIC-1012, ¶¶ 80-84.

These are predictable techniques and a POSITA would have been motivated to try


44

various combinations of these techniques to explore their relative merits, with a

reasonable expectation of success. ERIC-1012, ¶¶ 71-84.

Reasons for combining Baum with a cyclic prefix as taught by Laroia: It

would also have been obvious to modify Baum to use the cyclic prefix of Laroia.

Baum discloses use of a cyclic extension that is transmitted the back end of a

signal (but otherwise operates in the same manner as a cyclic prefix). ERIC- 1012,

¶ 85. Laroia discloses OFDM systems and methods that use a cyclic prefix.

ERIC- 1012, ¶ 87. Both Laroia and Baum use the cyclic prefix/extension in the

same manner, to account for potential interference. A POSITA would have been

motivated to modify Baum to use a cyclic prefix as taught by Laroia for the

following reasons. ERIC-1012, ¶¶ 85-88.

A POSITA would understand that the use of a cyclic prefix or extension is a

standard part of OFDM systems. Laroia explains that a cyclic prefix (or extension)

is “required to ensure orthogonality in a multipath environment.” ERIC-1009,

5:17-22. This is another way of saying that a purpose of a cyclic prefix/extension is

to eliminate intersignal interference (ISI). ERIC- 1012, ¶ 85. This is consistent

with the purpose of the cyclic extension in Baum, which is also to “eliminate inter-

symbol interference (ISI) and inter subcarrier interference (ICI) due to multipath

delay spread channels).” ERIC-1003, 3:64-66. Thus, a POSITA considering


45

Baum and Laroia would need to maintain some sort of cyclic extension or prefix

capability.

A POSITA would have been motivated to use the “cyclic prefix” approach

of Laroia. Baum discloses a “cyclic extension” embodiment that comes after the

transmitted signal and thus may not be a “prefix.” ERIC-1003, Figure 2. However,

cyclic extensions can come either before or after the underlying data signal. See

ERIC-1008, 2:23-42; ERIC- 1012, ¶ 86. Thus, Baum’s use of the term “cyclic

extension” is an express suggestion to use a cyclic prefix. ERIC-1012, ¶¶ 89-94.

Using Laroia’s cyclic prefix is also obvious because it is improving a similar

device or method (Baum’s SC-OFDM communication systems and methods) in the

same way (as disclosed in Laroia). ERIC-1012, ¶¶ 95-100. Use of a cyclic prefix

(as opposed to a cyclic suffix or post-fix) is also a simple substitution, a design

choice, and obvious to try because there are only two positions for placement of a

cyclic extension—either at the beginning or at the end of the signal—and it doesn’t

make a substantial difference which one is chosen. ERIC-1012, ¶¶ 101-118. Thus,

there is ample rationale for modifying Baum to use the cyclic prefix of Laroia.

Reasons for combining Baum with hopping pilot symbols as taught by

Laroia: As noted above for limitations [18.3]-[18.5], Baum discloses several

mechanisms for hopping training symbols and null symbols across different

positions. However, Baum does not provide any details regarding the frequency


46

hopping technique. ERIC-1003, 24:51-58. It would have been obvious to a

POSITA to use Laroia’s particular frequency hopping technique in the context of

Baum for the following reasons. ERIC-1012, ¶¶ 119-121.

First, Baum teaches that its pilot codes may be frequency hopped “according

to a predetermined frequency hopping method.” ERIC-1003, 24:51-58; ERIC-

1012, ¶ 123. This is an express teaching or suggestion to combine Baum with any

known frequency hopping techniques suitable for OFDM. Laroia discloses exactly

these types of hopping techniques for use with pilot codes of OFDM

communications. ERIC- 1012, ¶ 124.

Second, it was known to be desirable to provide frequency diversity of the

transmitted pilot codes over time to account for interference, poor channel

conditions, or other factors that may be associated with a particular frequency or

frequency range. For example, U.S. Patent Application Publication No.

2004/0166887 to Laroia et al. (“Laroia ’887”, ERIC-1005) also teaches inserting

training symbols and null subcarriers at positions identified by a frequency

hopping code. See, e.g., ERIC-1005, ¶¶ [0087]-[0089]. Laroia ’887 explains that

it may be desirable to hop the frequency positions over time “for various reasons

such as frequency diversity.” Id., ¶ [0087]. This also provides an express

motivation for a POSITA to use a frequency-hopping code as taught by Laroia to

select pilot code positions in Baum. ERIC- 1012, ¶¶ 125-126.


47

There are other additional reasons why it would have been obvious to

modify Baum to use the hopping codes of Laroia. Applying the frequency hopping

technique from Laroia would improve a similar method or system (Baum’s SC-

OFDM methods and systems) in the same way (providing frequency diversity).

ERIC-1012, ¶¶ 127-132. Further, using the hopping code of Laroia in lieu of

Baum’s general disclosure of frequency hopping is also mere simple substitution

(one hopping scheme for another) to obtain predictable results (the ability to

estimate channel conditions and provide frequency diversity). ERIC-1012, ¶¶ 133-

138; ERIC-1003, 4:62-65 (using pilot codes to estimate channel conditions).

Finally, the use of Laroia’s frequency hopping technique is obvious to try in the

context of Baum, since there are a finite number of available frequency hopping

techniques for OFDM. ERIC-1012, ¶¶ 139-145.

Based on the above, the subject matter of claim 18 of the ’185 patent would

have been obvious to a POSITA.

Dependent Claims 24 and 25

Dependent claims 24 and 25 are also rendered unpatentable by the

combination of Baum and Laroia. Because the claims are nearly identical and

involve the same evidence and arguments, they are grouped together for analysis.

[24.0] The method of claim 18, wherein inserting the training symbols into the first block of the two or more blocks of information-bearing symbols further comprises inserting the training symbols into the first block of the two or more blocks of information-bearing symbols such that there is at


48

least one information-bearing symbol between each of the training symbols in the first block of the two or more blocks of information-bearing symbols.

[25.0] The method of claim 18, wherein inserting the training symbols into the first and second blocks of the two or more blocks of information-bearing symbols further comprises inserting the training symbols into the first and second blocks of the two or more blocks of information-bearing symbols such that there is at least one information-bearing symbol between each of the training symbols in the first and second blocks of the two or more blocks of information-bearing symbols.

Claim 24 depends from claim 18 and further requires, in summary, that there

is “at least one information-bearing symbol between each of the training symbols

in the first block of . . . symbols.” Claim 25 also depends from claim 18 and

requires that the training symbols in both a first block and a second block be

separated by at least one information-bearing symbol. The combination of Baum

and Laroia render the subject matter of these claims obvious as follows:

Baum discloses a number of embodiments that satisfy the requirements of

claim 24 and claim 25. As one example, Dr. Akl shows how Figure 7 of Baum

shows an embodiment in which there are information-bearing symbols between the

training symbols in each block.


49

ERIC-1012, ¶¶ 203-204, 212-213. Dr. Akl provides similar illustrations for

Figures 8 and 12. Id. Figure 9 also shows pilot codes (which include training

symbols) that are time-separated from other training symbols on the same

subcarrier such that at least one data symbol is positioned between the training

symbols.

Laroia also shows embodiments in which pilot symbols are separated from

one another by at least one information-bearing symbol. Dr. Akl’s testimony

shows how Figure 4 of Laroia satisfies this claim element.

Annotated Fig. 7 of Baum

Information-bearing symbols

positioned between each of

the training symbols of the

pilot code.


Training symbols


50

ERIC-1012, ¶¶ 205, 214. Figure 3 of Laroia also provides pilot (i.e., training)

symbols that are separated from other pilot symbols by at least one information-

bearing symbol.

In addition, the proposed combination of Baum and Laroia also results in

training symbols that are separated from one another by at least one information-

bearing symbol. For example, the exemplary time-frequency grids discussed

above for claim limitation [18.5] are annotated below to illustrate the positioning

of at least one information-bearing symbol between the training symbols of the

pilot codes.

FIG. 4 of Laroia (annotated)


positioned between each of the training symbols of the

pilot code.


51

ERIC-1012, ¶¶ 209, 218. As shown, at least one information-bearing symbol (i.e.,

blank square) is positioned between each of the training symbols (i.e., X or -X) in

first and second groups of two or more symbols. For example, at least one

information-bearing symbol is positioned between each of the training symbols for

the first antenna (first group of two or more symbols) and the second antenna

(second group of two or more symbols). As another example, for each antenna, at

least one information-bearing symbol is positioned between each of the training

symbols for each of the baud intervals having training symbols, where each baud

interval is a group of two or more symbols (i.e., one baud interval is the first group


Time (OFDM symbols)

Fre

quen

cy

(Sub

carr

iers

)

Time (OFDM symbols)

Fre

quen

cy

(Sub

carr

iers

)



positioned between each of the training symbols of the

pilot code.


52

of two or more symbols and another baud interval is the second group of two or

more symbols). See generally ERIC-1012, ¶¶ 203-220.

This combination of Baum and Laroia would have been obvious for the

same reasons stated above in regards to claim 18. Based on the above, the

combination of Baum and Laroia render claims 24 and 25 obvious.

2. Challenge #2: Claims 1, 6, 9, and 15 are unpatentable as obvious under 35 U.S.C § 103 over Baum in view of Laroia and Siew.

The combination of Baum, Laroia and Siew render obvious claims 1, 6, 9,

and 15 of the ’185 patent. See ERIC-1012, ¶¶ 221-382.

Independent Claim 1

[1.0] A method comprising:

This limitation is disclosed for the reasons stated above for limitation [18.0].

See also ERIC- 1012, ¶¶ 261-262.

[1.1] in a base station:


See also ERIC- 1012, ¶¶ 263-265.

[1.2] forming two or more blocks of output symbols for orthogonal frequency division multiplexing (OFDM) transmissions over a multiple-input multiple-output (MIMO) channel,


See also ERIC- 1012, ¶¶ 266-271.


53

[1.3] wherein the forming comprises (i) identifying different positions within the two or more blocks of output symbols based at least on (a) one or more block index values, (b) one or more subcarrier index values, (c) a cyclic prefix parameter selected to compensate for intersymbol interference (ISI) associated with the MIMO channel, and (d) a hopping code that is based, at least in part, on the cyclic prefix parameter, and

Most of the elements of this limitation are disclosed for the reasons stated

above for limitation [18.3] (which uses similar language to claim the same

concepts). See ERIC- 1012, ¶¶ 272-286. The only limitation that is not discussed

for limitation [18.3] is the requirement of “a hopping code that is based, at least in

part, on the cyclic prefix parameter.”3 This element is disclosed by the

combination of Baum, Laroia, and Siew.

As noted above for limitation [18.3], the combination of Baum and Laroia

discloses that the cyclic prefix length (i.e., the recited cyclic prefix parameter) is

used to position the symbols. Laroia also describes that the hopping code is based

on the number of subcarriers, which is, in turn, dependent on the cyclic prefix

length. Laroia thus discloses a hopping code that is based, at least in part, on a

cyclic prefix length. ERIC-1012, ¶ 287.

As a general matter, the number of available subcarriers determines the

available positions in the frequency dimension for the symbols of the pilot code to

hop between. ERIC-1012, ¶ 288. Because the symbols of the pilot code must be

3 Claim 18 requires selecting a position based on a hopping code and a cyclic prefix parameter, but it does not require that the hopping code itself be based on the cyclic prefix parameter.


54

assigned to one of the available subcarriers to be transmitted, the hopping code

must be based, at least in part, on the available subcarriers. Id. This is consistent

with Laroia, which discloses that its hopping codes depend on the number of

available subcarriers in its mathematical equations. See ERIC-1009, 2:34-35;

4:11-22; ERIC-1012, ¶ 288-289.

Laroia also discloses that the number of available subcarriers in the system

is dependent on the cyclic prefix length. Specifically, Laroia states that “[t]he

number of tones into which a certain bandwidth can be divided into depends on

parameters of the system, such as . . . the length of a cyclic prefix.” ERIC-1009,

5:17-22. Because Laroia discloses a hopping code that depends on the number of

subcarriers, which in turn depends on a cyclic prefix parameter (i.e., cyclic prefix

length), it discloses element (d) of limitation [1.3]. ERIC- 1012, ¶ 287.

In addition, Siew discloses that the number of subcarriers used for

transmitting symbols of a pilot code from the total number of available subcarriers

can be selected based on the cyclic prefix length and the number of transmit

antennas. Among other teachings, Siew teaches how to create a “training

sequence” that includes “pilot symbols on select subcarriers.” ERIC-1010, p.2.

Siew explains that the “total number of subcarriers needed for pilot symbols are κ

≥MCP, where CP is the size of the Cyclical Prefix of the OFDM symbol.” Id.

(emphasis added). Using Siew’s technique (based on the cyclic prefix length) to


55

select the number of subcarriers used by the hopping code for pilot code symbols

from among the total available subcarriers (also based on the cyclic prefix length),

results in a hopping code that is based in part on the cyclic prefix length. ERIC-

1012, ¶¶ 290-296.

[1.4] (ii) inserting, based at least on the hopping code, training symbols and null subcarriers within two or more blocks of information-bearing symbols, the hopping code directing at least a portion of the null subcarriers to be inserted at the different positions within the two or more blocks of output symbols; and

This limitation is similar in many respects to limitations [18.4] and [18.5]

discussed above. Accordingly, the analysis of [18.4] and [18.5] is incorporated

here. However, [1.4] requires the inserting to be based on “the hopping code,”

which as discussed above is required to be based on the cyclic prefix parameter in

claim 1. As discussed above, the combination of Baum, Laroia, and Siew discloses

identifying different positions as required by [1.3], including being based on a

hopping code that is base, at least in part, on a cyclic prefix parameter. See ERIC-

1012, ¶¶ 297-302.

Dr. Akl provides several diagrams showing the insertion of training symbols

and null subcarriers at the positions identified in accordance with the disclosures of

Baum, Laroia, and Siew as discussed above with respect to [1.3]. For example, Dr.

Akl has testified that the following time-frequency grids illustrate insertion of

training symbols and null subcarriers at positions, identified by a hopping code


56

based at least in part on a cyclic prefix, within groups of two or more information-

bearing symbols such that the null subcarriers are inserted at different positions

within the two or more groups of two or more output symbols as taught by Baum,

Laroia, and Siew.


57

Frequency hopping based on FIG. 9 of Baum, Fig. 3 of Laroia, and Siew

Time (OFDM symbols)

Fre

quen

cy

(Sub

carr

iers

)

Time (OFDM symbols)

Fre

quen

cy

(Sub

carr

iers

)

Antenna 1 (Pilot Code W1): Antenna 2 (Pilot Code W1): Null subcarriers at

different subcarrier positions between antennas

Null subcarriers at

different subcarrier positions

between baud intervals


58

As shown, for both examples (with and without pilot code hopping) the

training symbols and null subcarriers are inserted at the positions identified by the

A combination of pilot code hopping and frequency hopping based on FIG. 9 of Baum,

Fig. 3 of Laroia, and Siew

Time (OFDM symbols)

Fre

quen

cy

(Sub

carr

iers

)

Time (OFDM symbols)

Fre

quen

cy

(Sub

carr

iers

)

Antenna 1: Antenna 2: Null subcarriers at

different subcarrier positions between antennas

Null subcarriers at

different subcarrier positions

between baud intervals


59

hopping code such that the null subcarriers are inserted at different positions within

the two or more groups of two or more output symbols. For example, the positions

of the null subcarriers within the group of symbols for antenna 1 are different from

the positions of the null subcarriers within the group of symbols for antenna 1. As

another example, for each antenna, the positions of the null subcarriers within the

group of symbols in the first baud interval are different from the positions of the

null subcarriers within the group of symbols in the fourth and seventh baud

intervals. As yet another example, if a slot structure is utilized as disclosed in

Baum (e.g., consisting of 4 baud intervals and 5 subcarriers as shown in Fig. 12 of

Baum), then the positions of the training symbols and null subcarriers within the

group of symbols of a slot are different from (1) the positions of the training

symbols and null subcarriers within the group of symbols in other slots of the same

antenna as well as (2) the positions of the training symbols and null subcarriers

within the group of symbols in slots of the other antenna. ERIC- 1012, ¶¶ 303-305.

As shown, in each of these examples, a first null subcarrier is inserted within a first

group of two or more output symbols at a first subcarrier position and a second null

subcarrier is positioned within a second group of two or more output symbols at a

second subcarrier position that is different than the first subcarrier position.

Thus, the combination of Baum, Laroia, and Siew discloses limitation [1.4]

for the reasons stated above for limitations [18.4] and [18.5].


60

[1.5] transmitting, via two or more antennas, transmission signals in accordance with the two or more blocks of output symbols, wherein the two or more blocks of output symbols include a first block of output symbols and a second block of output symbols, and

As noted for limitation [1.2], Baum discloses transmitting over a MIMO

channel (i.e., over a system having multiple transmit antennas and multiple receive

antennas). ERIC-1003, Abstract, 8:23-26; ERIC- 1012, ¶¶ 306-308. Baum also

discloses the transmission of transmission signals in accordance with the blocks of

output symbols as formed in accordance with [1.2]-[1.4]. See, e.g., Fig. 2 and

Figure 12 (showing transmission of multiple baud intervals and multiple slots). As

discussed above, the blocks of output symbols formed in accordance with [1.2]-

[1.4] include a first block of output symbols and a second block of output symbols.

Baum’s teaching to use multiple antennas to transmit signals according to the

output symbol blocks (e.g., baud intervals, slots, etc.) satisfies the elements of

limitation [1.5]. ERIC-1012, ¶¶309-310.

[1.6] wherein inserting the training symbols and null subcarriers comprises: inserting a first null subcarrier at a first subcarrier position within the first block of output symbols; and inserting a second null subcarrier at a second subcarrier position within the second block of output symbols, wherein the first subcarrier position is different from the second subcarrier position.

Limitation [1.6] is taught or rendered obvious by the combination of Baum,

Laroia, and Siew. As discussed above with respect to limitation [1.4] and shown in

exemplary time-frequency grids reproduced there, the combination of Baum,


61

Laroia, and Siew discloses inserting null subcarriers (i.e., null symbols) within two

or more blocks of information-bearing symbols at different subcarrier positions.

ERIC-1012, ¶¶ 311-315.

Thus, the combination of Baum, Laroia, and Siew disclose the elements of

limitation [1.6].

Claim 1 Obviousnsess Rationale

The rationale for combining Baum and Laroia together is the same for claim

1 as established above for claim 1. The rationale for further combining Siew with

Baum and Laroia is set forth below. ERIC-1012, ¶ 223.

As discussed above, the combination of Baum and Laroia discloses

frequency hopping the pilot symbols of orthogonal pilot codes. Baum discloses

that the pilot symbols and null symbols of a pilot code can be distributed in any

manner across time and frequency and Laroia describes pilot tone hopping

sequences where “the locations are specified by periodic pilot tone hopping

sequences.” ERIC-1003, 13:7-11; ERIC-1009, Abstract. Further, Laroia explains

that “[t]he number of tones into which a certain bandwidth can be divided into

depends on parameters of the system, such as, the data rate to be supported on each

individual tone and the length of a cyclic prefix that is required to be used to

ensure orthogonality in a multipath environment.” ERIC-1009, 5:17-22. That is,

Laroia teaches that the number of tones (i.e., subcarriers) available for transmission


62

of pilot symbols and data symbols is dependent on system parameters, such as the

cyclic prefix length and data rate. As a result, the number of subcarriers available

for transmitting and hopping the pilot symbols of Baum’s orthogonal pilot codes

between is likewise dependent on the cyclic prefix length.

Baum and Laroia do not explicitly disclose selecting the number of

subcarriers for the pilot symbols to hop between based on the cyclic prefix length.

However, in the same field of OFDM communication systems and methods, Siew

explicitly describes selecting the number of subcarriers for the pilot symbols based

on the cyclic prefix length and the number of transmit antennas. ERIC-1012, ¶¶

224-226.

Siew explains that “the minimum number of pilot symbols needed per

transmit antenna is dependent on the channel order, L. Hence, for a training

sequence, the total number of subcarriers needed for pilot symbols are, κ ≥

MCP, where CP is the size of the Cyclical Prefix of the OFDM symbol” and M is

the number of transmit antennas. ERIC-1010, p.2. Siew further explains that

“[i]deally, κ should be determined by L. However, since systems are designed with

a predetermined CP length and subcarrier orthogonality is lost when L > CP, it is

only sensible to design a training sequence for the worst case. Obviously, for a

fixed CP size, M is limited to K/CP.” Id. Accordingly, Siew discloses that the

number of subcarriers used for transmitting the pilot symbols of a pilot code is


63

selected based on the cyclic prefix length and the number of transmit antennas.

ERIC-1012, ¶¶ 227-228.

A POSITA considering the combination of Baum and Laroia in a MIMO

configuration would have been motivated to use the teachings of Siew to determine

the minimum number of pilot symbols needed for the hopping code. This would

be using a known technique (Siew) to improve a known system/method (the

hopping codes of Baum and Laroia) in the same way to achieve predictable results.

ERIC- 1012, ¶¶ 229-236. For similar reasons, this combination would have been

obvious as a simple substitution of Siew’s technique of determining the number of

subcarriers to use for pilot code symbols based on cyclic prefix length in lieu of the

selection techniques of Baum and Laroia. ERIC- 1012, ¶¶ 237-244. Similarly,

given that there are only a limited number of ways to determine the number of

subcarriers to use for pilot code symbols such that using Siew’s approach based on

cyclic prefix length would have been both a design choice and obvious to try.

ERIC- 1012, ¶¶ 245-260.

Dependent Claim 6

[6.0] The method of claim 1, wherein inserting the training symbols and the null subcarriers comprises inserting at least one training symbol adjacent to at least one null subcarrier.

The combination of Baum, Laroia, and Siew renders obvious the limitations

of claim 6. For example, as discussed above, the time-frequency grids from [1.4]


64

illustrate the insertion of pilot codes having training symbols and null subcarriers

within first and second blocks of output symbols as taught by the combination of

Baum, Laroia, and Siew. ERIC-1012, ¶¶ 316-318. As shown in the annotated

versions below, the time-frequency grids for both examples (with and without pilot

code hopping) have at least one training symbol inserted adjacent to at least one

null subcarrier.


65

Frequency hopping based on FIG. 9 of Baum, Fig. 3 of Laroia, and Siew

Time (OFDM symbols)

Fre

quen

cy

(Sub

carr

iers

)

Time (OFDM symbols)

Fre

quen

cy

(Sub

carr

iers

)

Antenna 1 (Pilot Code W1): Antenna 2 (Pilot Code W1):

Training symbol

adjacent to null

subcarrier.


66

The combination of Baum, Laroia, and Siew therefore renders obvious the

limitations of claim 6. ERIC-1012, ¶¶ 319-321.

A combination of pilot code hopping and frequency hopping based on FIG. 9 of Baum,

Fig. 3 of Laroia, and Siew

Time (OFDM symbols)

Fre

quen

cy

(Sub

carr

iers

)

Time (OFDM symbols)

Fre

quen

cy

(Sub

carr

iers

)


Training symbol

adjacent to null

subcarrier.


67

Independent Claim 9

Claim 9 is a system claim that uses identical or nearly identical limitations as

corresponding method claims 1 and 18. The analysis below largely incorporates

by reference the discussion of those claim elements. The fact that claim 9 is

directed to a system rather than a method does not make a difference for purposes

of this Petition because the prior art discloses OFDM systems that implement the

OFDM communication methods. The combination of Baum, Laroia, and Siew

thus renders obvious claim 9 for the similar reasons as stated above for claims 1

and 18.

[9.0] A system, comprising:

To the extent the preamble is limiting, the combination of Baum, Laroia, and

Siew discloses a system. Baum is entitled “Synchronous Coherent Orthogonal

Frequency Division Multiplexing System, Method, Software, and Device.” ERIC-

1003, Title (emphasis added). Baum discloses systems for “reducing the impact of

interference in OFDM wireless communication systems.” Id., 1:7-10. Thus, the

asserted prior art discloses “a system,” as recited in the preamble of claim 1.

ERIC-1012, ¶ 322.

[9.1] two or more antennas; and

As noted above, Baum discloses a MIMO channel having multiple transmit

antennas. ERIC-1003, 8:23-26 (transmitting via “an array of antennas.”). Siew

also discloses a MIMO channel (which has two or more antennas). ERIC-1012,


68

¶¶ 323-325.

[9.2] a base station configured to

This limitation is disclosed for the reasons stated above with regards to

corresponding claim limitation [18.1]. See also ERIC-1012, ¶¶ 326-328.

[9.3] (i) form two or more blocks of output symbols for orthogonal frequency division multiplexing (OFDM) transmissions over a multiple-input multiple-output (MIMO) channel by



[9.4] identifying different positions within the two or more blocks of output symbols based at least on (a) one or more block index values, (b) one or more subcarrier index values, (c) a cyclic prefix parameter selected to compensate for intersymbol interference (ISI) associated with the MIMO channel, and (d) a hopping code that is based, at least in part, on the cyclic prefix parameter, and



[9.5] inserting, based at least on the hopping code, training symbols and null subcarriers within two or more blocks of information-bearing symbols, the hopping code directing at least a portion of the null subcarriers to be inserted at the different positions within the two or more blocks of output symbols, and



[9.6] (ii) transmit, via the two or more antennas, transmission signals in accordance with the two or more blocks of output symbols, wherein the two or more blocks of output symbols include a first block of output symbols and a second block of output symbols, and


69



[9.7] wherein the base station is further configured to: insert a first null subcarrier at a first subcarrier position within the first block of output symbols; and insert a second null subcarrier at a second subcarrier position within the second block of output symbols, wherein the first subcarrier position is different from the second subcarrier position.


corresponding claim limitation [1.6]. See also ERIC-1012, ¶ 372-376.

Claim 9 Obviousness Rationale

Claim 9 is rendered obvious by Baum, Laroia, and Siew for the same

reasons as stated above for claims 1 and 18. The obviousness rationale discussion

of claim 18 provides the reasons why it would have been obvious to combine

Baum and Laroia to satisfy most of the claim elements. The obviousness

discussion of claim 1 provides the reasons why it would have been obvious to

further modify Baum and Laroia with the teachings of Siew. The same analysis

applies with respect to claim 9. As noted above, the fact that claim 9 is a system

claim rather than a method claim does not impact the obviousness rationale

analysis since Baum, Laroia, and Siew disclose implementing OFDM methods

within an OFDM system as claimed. Thus, claim 9 is rendered obvious by Baum,

Laroia, and Siew. See ERIC-1012, ¶¶ 223-260.

Dependent Claim 15


70

[15.0] The system of claim 9, wherein the base station is configured to insert at least one training symbol adjacent to at least one null subcarrier.

This claim is rendered obvious by the combination of Baum, Laroia, and

Siew for the reasons stated above with regards to corresponding claim [6.0]. See

also ERIC-1012, ¶¶ 377-382.

3. Challenge #3: Claim 10 is unpatentable as obvious under 35 U.S.C § 103 over Baum in view of Laroia, Siew, and Barton.

Dependent Claim 10

[10.0] The system of claim 9, further comprising: a wireless communication device configured to receive the transmission signals as received signals, wherein the wireless communication device is configured to (i) estimate a carrier frequency offset based on the received signals and (ii) perform channel estimation of the MIMO channel based on the received signals.

Claim 10 is rendered obvious by the combination of Baum, Laroia, Siew,

and Barton. ERIC-1012, ¶¶ 383-412.

The system of claim 9: As discussed above for limitation [9.0], Baum discloses

a system. See ERIC-1012, ¶ 322.

further comprising: a wireless communication device configured to receive the

transmission signals as received signals: Baum states that it “relates generally to . . .

OFDM wireless communications systems.” ERIC-1003, 1:7-11. Baum’s teachings

“include a plurality of SC-OFDM transmitters and a plurality of SC-OFDM

receivers,” where “[t]he plurality of SC-OFDM receivers is arranged to receive the

SC-OFDM signals from at least one of the plurality of SC-OFDM transmitters.” Id.,


71

Abstract. Barton also discloses a wireless communication device configured to receive

the transmission signals. ERIC-1004, Abstract (“the system is arranged to support

high-speed . . . wireless access services.”). ERIC-1012, ¶¶ 407-408. Thus, Baum

discloses this claim element.

wherein the wireless communication device is configured to (i) estimate a

carrier frequency offset based on the received signals and: Baum discloses

transmission signals that provide information for estimating a carrier frequency offset.

Baum explains that “the measurement and compensation of subcarrier phase

difference in OFDM signals may be based on methods in the art for measuring and

compensating a frequency offset in time domain signals.” ERIC-1003, 22:1-6;

ERIC-1012, ¶¶ 408-409 (emphasis added).

Barton also discloses methods for measuring and compensating carrier

frequency offset based on the received versions of the transmitted signals. See, e.g.,

ERIC-1004, 15:5 – 16:62; ERIC-1012, ¶¶ 383-384. Barton teaches that pilot symbols

can be used by a receiver for “Symbol Timing and Carrier Frequency Offset

Estimation.” ERIC-1004, 11:39-41. More specifically, Barton explains that the pilot

symbols used for carrier frequency offset (CFO) estimation “are simply null symbols,

i.e. 0.” Id., 11:45-50. Accordingly, Barton discloses that the null symbols transmitted

in the OFDM transmission signals, such as those of Baum, are used for CFO

estimation. ERIC-1012, ¶ 410.


72

(ii) perform channel estimation of the MIMO channel based on the received

signals: As discussed above for limitation [18.2], Baum discloses a MIMO channel.

Baum also discloses channel estimation, noting that “A multi-channel channel

response estimator is used to estimate the channel response of signals from a

plurality of SC-OFDM transmitters.” ERIC-1003, 15:1-11 (emphasis added).

Baum also discloses that one of the preferred embodiments of SC-OFDM is to use

“pilot codes rather than individual pilot symbols in each OFDM slot for channel

response estimation.” Id., 4:41-44; 5:24-26 (emphasis added). Performing such

channel estimation based on the signal received from the plurality of transmit

antennas in the context of a MIMO channel satisfies this claim element. ERIC-1012,

¶¶ 408-412.

Obviousness Rationale for Claim 10

Baum discloses all of the dependent claim elements of claim 10, but describes

the measurement of carrier frequency offsets only generally. Barton provides details

that a POSITA would rely on in implementing the teachings of Baum. Whereas

Baum simply notes that “subcarrier phase difference in OFDM signals may be based

on methods in the art for measuring and compensating a frequency offset in time

domain signals,” Barton describes in detail methods for measuring and compensating

for carrier frequency offset. ERIC-1003, 22:2-6; ERIC-1004, 15:5-16:62. A POSITA

would have been motivated to use Barton’s technique for measuring carrier frequency


73

offset due to Baum’s express teaching that detecting the frequency offset “may be

based on methods in the art for measuring and compensating a frequency offset.”

ERIC-1003, 22:2-6; ERIC-1012, ¶¶ 385-394.

Further, using Barton’s carrier frequency offset measurement techniques in

Baum would also have been obvious because it would be using a known technique

(Barton’s CFO estimation technique) to improve a similar device or method (Baum’s

SC-OFDM communication systems and methods) in the same way. Id., ¶¶ 395-400.

Barton’s CFO estimation techniques are also obvious to try, as there are a limited

number of known ways to do CFO estimation. Id., ¶ 401-406.

Based on the above, the combination of Baum, Laroia, and Siew, as further

modified by Barton, renders claim 10 obvious.

VII. CONCLUSION

For the reasons set forth above, Ericsson asks that the Patent Office order an

inter partes review trial and then proceed to cancel claims 1, 6, 9, 10, 15, 18, 24, and

25 of the ’185 patent. The undersigned further authorizes payment for any additional

fees that may be due in connection with this Petition to be charged to Deposit Account

No. 08-1394.


74

Respectfully submitted, /J. Andrew Lowes/ J. Andrew Lowes Counsel for Petitioner Registration No. 40,706 HAYNES AND BOONE, LLP Telephone: (972) 680-7557

Dated: March 30, 2017


PETITIONER’S EXHIBIT LIST

Exhibit Number

Description

1001 U.S. Patent No. 8,774,185 (“the ’185 Patent”) 1002 Prosecution History of the ’185 Patent 1003 U.S. Patent No. 5,867,478 to Baum et al. (“Baum”) 1004 U.S. Patent No. 6,449,246 to Barton et al. (“Barton”) 1005 U.S. Patent Application Publication No. 2004/0166887 to Laroia

et al. (“Laroia ’887”) 1006 U.S. Provisional Patent Application No. 60/449,729 to Laroia et

al. (“Laroia Provisional”) 1007 Ma, Xiaoli, Giannakis, Georgios B., and Barbarossa, Sergio,

“Non-Data-Aided Carrier Offset Estimators for OFDM With Null Subcarriers: Identifiability, Algorithms, and Performance” (“Ma”)

1008 U.S. Patent No. 6,928,046 to Sajadieh et al. (“Sajadieh”) 1009 U.S. Patent No. 6,954,481 (“Laroia”) 1010 Siew et. Al, “A Channel Estimation Method for MIMO-OFDM

Systems (‘Siew”) 1011 Declaration of David Bader 1012 Declaration of Dr. Akl 1013 Plaintiff’s Opposition to Ericsson’s Motion to Intervene 1014 Transcript from Oral Hearing regarding Motion to Intervene 1015 Decision Granting Motion to Intervene 1016 Declaration of John Mitchell regarding the Siew reference.


CERTIFICATE OF WORD COUNT

Pursuant to 37 CFR § 42.24, the undersigned hereby certifies that according

to Microsoft Word’s automatic word-counting tool, there 13,918 words in this

paper, not including table of contents, table of authorities, mandatory notices under

§ 42.8, certificate of service or word count, or appendix of exhibits or claim listing.

/J. Andrew Lowes/ J. Andrew Lowes Counsel for Petitioner Registration No. 40,706


CERTIFICATE OF SERVICE

The undersigned hereby certifies that a copy of the foregoing Petition for

Inter Partes Review of U.S. Patent No. 8,718,185, and associated exhibits, were

served on the following counsel on March 30, 2017 by Express Mail as follows:

Fish & Richardson P.C. (TC) P.O. Box 1022 Minneapolis MN 55440-1022

/J. Andrew Lowes/ J. Andrew Lowes Counsel for Petitioner Registration No. 40,706

united states patent and trademark office before the ... · the real party-in-interest is ericsson...

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