Acorn Technologies, Inc.

Patent Trials and Appeals Board

Jun 12, 2020

2019000738 (P.T.A.B. Jun. 12, 2020)

UNITED STATES PATENT AND TRADEMARK OFFICE
UNITED STATES DEPARTMENT OF COMMERCE
United States Patent and Trademark Office
Address: COMMISSIONER FOR PATENTS
P.O. Box 1450
Alexandria, Virginia 22313-1450
www.uspto.gov
APPLICATION NO. FILING DATE FIRST NAMED INVENTOR ATTORNEY DOCKET NO. CONFIRMATION NO.
14/811,507 07/28/2015 Steven C Thompson 21074.4042 5808
7590 06/12/2020
William H. Wright
703 Pier Ave
Ste B # 357
Hermosa Beach, CA 90254
EXAMINER
LIU, JUNG-JEN
ART UNIT PAPER NUMBER
2473
MAIL DATE DELIVERY MODE
06/12/2020 PAPER
Please find below and/or attached an Office communication concerning this application or proceeding.
The time period for reply, if any, is set in the attached communication.
PTOL-90A (Rev. 04/07)

UNITED STATES PATENT AND TRADEMARK OFFICE
____________

BEFORE THE PATENT TRIAL AND APPEAL BOARD
____________

Ex parte STEVEN C. THOMPSON and
FERNANDO LOPEZ DE VICTORIA
____________

Appeal 2019-000738
Application 14/811,507
Technology Center 2400
____________

Before MAHSHID D. SAADAT, CARL L. SILVERMAN, and
MICHAEL J. ENGLE Administrative Patent Judges.

SILVERMAN, Administrative Patent Judge.

DECISION ON APPEAL
Appellant1 appeals under 35 U.S.C. § 134(a) from the Examiner’s
Final Rejection2 of claims 1–6, 8–12, 14–17, 20–22, and 24–31. We have
jurisdiction under 35 U.S.C. § 6(b). A telephonic Hearing was held May 14,
2020.
We REVERSE.

1 Throughout this Decision, we use the word “Appellant” to refer to
“applicant” as defined in 37 C.F.R. § 1.42(a). Appellant identifies Acorn
Technologies, Inc. as the real party in interest. Appeal Br. 2.
2 The Examiner states claims 5, 11, 15, 22, and 24–31 are allowable. Ans.
46.
Appeal 2019-00738
Application 14/811,507
2
STATEMENT OF THE CASE
The invention relates to determining time of arrival in a wireless
network using matching pursuit. Abstract; Spec. ¶¶ 17; Figs. 6, 7. Claim 1,
reproduced below, is exemplary of the subject matter on appeal (emphases
added):
1. A method of determining time of arrival in a wireless
network, comprising:
receiving at a receiver from a wireless network a signal
comprising a plurality of orthogonal frequency division multiplexing
signals from a single base;
extracting location pilot signals from the received signal;
determining a power delay profile corresponding to the
extracted location pilot signals;
identifying a first path associated with the extracted location
pilot signals by performing matching pursuit estimation on the power
delay profile for the extracted location pilot signals;
determining a time of arrival based on the identified first path.

Appeal Br. (Claims App’x 1).

THE REJECTION
Claims 1–6, 8–12, 14–17, 20–22, and 24–31 are rejected under
35 U.S.C. § 103(a) as being unpatentable over Kangas in view of
Annavajjala. Final Act. 4–32.

REFERENCES
Prior art relied upon by the Examiner:
Name Reference Date
Kangas et al. US 2011/0143773 Al June 16, 2011
Annavajjala et al. US 2012/0082252 Al Apr. 5, 2012

ANALYSIS
Appeal 2019-00738
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The Examiner finds the combination of Kangas and Annavajjala
teaches the limitations of claim 1. Final Act. 4–14; Ans. 31–44. The
Examiner finds Kangas teaches equations utilized to estimate the arrival
time but “does not elaborate MP–PDP.” Final Act. 11 (citing Kangas ¶¶ 78,
80, 81, 116, 117; Figs. 2–6B). The Examiner’s use of “MP–PDP” appears to
refer to claim 1 terms “matching pursuit” and “power delay profile.” The
term “PDP” refers to “power delay profile” and the term “MP” refers to
“matching pursuit.” Spec. ¶¶ 24, 25, 57, 61, 62, 64 for “PDP;” ¶¶ 29, 30, 33,
41, 46, 48 for “MP;” ¶¶ 24, 25, Figs. 6, 7 for “MP–DP.” The Examiner then
finds Annavajjala teaches the claimed use of “matching pursuit” and “power
delay profile.” Final Act. 11–13 (citing Annavajjala ¶¶ 23, 25–30; Figs. 2,
3).
According to the Abstract, “[a] wireless receiver receives location
pilots embedded in received symbols and uses the location pilots to detect
the first path for every base station the network has designated for the
receiver to use in time of arrival estimation” and “[t]he receiver preferably
applies matching pursuit strategies to offer a robust and reliable
identification of a channel impulse response’s first path.” Appellant asserts
the claimed method determines a power delay profile (PDP) by computing
the absolute value squared of the correlator output. Appeal Br. 2–3 (citing
Figs. 6, 7; Spec. ¶ 61). Appellant asserts the receiver then determines a
channel impulse response using matching pursuit on the power delay profile
to determine time of arrival. Id. at 3 (citing Spec. ¶¶ 45, 56, 62, 64).
According to Appellant, the claimed invention relates to identifying first
paths using matching pursuit analysis on the power delayed profiles and this
is a comparatively simple process using less complicated circuitry in part
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because the power delay profile is real valued and does not contain phase
information. Id. at 4 (citing Spec. ¶¶ 61, 63).
Appellant argues, inter alia, the Examiner errs because neither
Kangas nor Annavajjala teaches performing matching pursuit estimation on
a power delay profile as recited in claim 1 “identifying a first path associated
with the extracted location pilot signals by performing matching pursuit
estimation on the power delay profile for the extracted location pilot signals”
(also referred to as “disputed limitation”). Appeal Br. 13–14. Appellant
argues “power delay profile” is a well-understood term that describes the
power received through a multipath channel as a function of delay and,
because the power delay profile describes power, it is a real quantity. Id. at
13–14. Appellant argues Annavajjala does not teach the claimed “power
delay profile:”
In contrast, the Annavajjala publication describes performing
matching pursuit on complex-valued signals to determine the
complex-valued function h[k]. It is clear from how the
Annavajjala publication describes the signals used to determine
h[k] that these signals cannot be a power delay profile. This
conclusion is confirmed by how the Annavajjala publication
describes the power delay profile. Indeed, the Annavajjala
publication teaches that the power delay profile is not available
at the receiver and cannot be used in characterizing the channel.
See Annavajjala at ¶ 26 (“a power delay profile (PDP) of the
channel is assumed to be fixed even when the instantaneous
channel gain is time-varying”), ¶ 30 (“PDP is a constant or
exponentially decaying function”).
The present application teaches that performing matching
pursuit on a power delay profile is a fast and efficient way to
characterize a channel to facilitate identifying a first path,
determining a time of arrival and, as desired, a receiver
location. One of ordinary skill in the art reviewing the
Annavajjala publication would find the claims of the present
application to be directly contrary to the teachings of the
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Annavajjala publication. The Annavajjala publication refers to
a power delay profile in two paragraphs, 26 and 30. In each,
the Annavajjala publication makes clear that it does not use the
power delay profile and instead makes assumptions about the
power delay profile because, as explicitly stated in paragraph
30, the power delay profile “is not available at the receiver”
(and so cannot be used to determine a power delay profile for a
specific set of pilot signals). First, paragraph 26 states that the
“power delay profile (PDP) of the channel is assumed to be
fixed.” Second, paragraph 30 states “that the PDP is a constant
or exponentially decaying function.” Thus, because the power
delay profile “is not available at the receiver,” Annavajjala at
¶ 30, the Annavajjala publication assumes that the power delay
profile is a constant value or the same simplistic function. Id. at
¶ 30. By assuming that the power delay profile is always a
constant value or the same simplistic function, the Annavajjala
publication shows that it does not use the power delay profile in
characterizing the channel.
In addition, these assumptions show that the Annavajjala
publication’s power delay profile does not correspond to the set
of extracted location pilot symbols. For any set of location
pilot symbols, the Annavajjala publication would assume the
same trivial power delay profile. As an example, the
Annavajjala publication would assume the same power delay
profile even if its system were presented with sets of location
pilot symbols from two different, distinctly located servers. As
an even more degenerate example, the Annavajjala publication
would assume the same power delay profile even when there
are no location servers and no location pilot signals present.
Accordingly, the Annavajjala publication does not
describe or suggest performing matching pursuit on a power
delay profile for any purpose, much less for identifying a first
path. Because neither of the cited references describe or
suggest performing matching pursuit on a power delay profile,
the rejections of the pending claims should be reversed.

Id. at 14–15.
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Appellant argues neither Kangas nor Annavajjala teaches “performing
matching pursuit on a power delay profile.” Appeal Br. 13–14. According
to Appellant, the Examiner acknowledges that Kangas does not disclose
“MP-PDP,” and Annavajjala’s disclosure of matching pursuit is to determine
a complex valued impulse response h[k]. Id. at 13 (citing Annavajjala ¶¶ 21,
25). Appellant additionally argues Annavajjala does not describe or suggest
performing matched pursuit estimation on a (real-valued) power delay
profile, as in claim 1. Id.
In the Answer, the Examiner utilizes a Table to map claim 1 to
Kangas and Annavajjala. Ans. 32–37. The Examiner additionally finds
Kangas discloses creating power spectra density, a type of received signals
power profile. Id. at 33 (citing Table, row 4). The Examiner finds Kangas
teaches “correlating or matching” delayed output signals. Id. at 35 (citing
Table, row 6). The Examiner finds Annavajjala’s complex values comprise
real-value and imaginary-value components and “Annavajjala’s invention is
patentably equivalent and work with real-value operations.” Id. at 40–41
(citing Annavajjala ¶ 96). The Examiner notes that the claim does not recite
“real-value power delay profile” (emphasis added). Id. at 41.
In the Reply Brief, Appellant argues the Answer includes new
arguments and does not correctly summarize Appellant’s arguments. Reply
Br. 2–3 (citing Ans. 32–37). Appellant argues the Examiner does not rebut
Appellant’s argument that neither Kangas nor Annavajjala performs
matching pursuit on a power delay profile. Id. at 4. Appellant argues the
Examiner errs in suggesting that the Kangas power spectral density is a
power delay profile. Id. at 6. According to Appellant, Kangas does not
describe or suggest a power delay profile, because Kangas’ power spectral
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density does not vary over time and, instead, the Examiner discusses another
term (“a type of received signals power profile”). Id. at 6–7. Appellant
argues the Examiner errs in finding Kangas’ “correlation” corresponds to
matching pursuit estimation because matching pursuit estimation involves
signal modeling whereas correlation is a form of signal analysis. Reply Br.
5 (citing Ans. 35; Kangas equation 4). Additionally, Appellant argues
Annavajjala and the Specification expressly describe correlation as a distinct
operation prior to matching pursuit estimation. Id. at 15, 16 (citing
Annavajjala ¶ 25; Spec. ¶¶ 44, 45, 60–62, Fig. 6).
Appellant argues the Examiner errs in finding Annavajjala teaches
using power delay profile to detect pilot signals in the communication
channel. Id. at 7 (citing Ans. 34). According to Appellant:
There is simply nothing in Annavajjala to support the assertion
that “Annavajjala discloses using ‘Power Delay Profile’ (PDP)
to detect pilot signals in the communication channel.” This is
readily apparent because OFDM receivers receive pilot signals
from the communication channel and use those received
pilot signals to characterize the channel (i.e., channel estimation).
There is no need to use a power delay profile or any calculation
to detect the pilot signals; rather this is accomplished by the
receiver front end electronics before any processing occurs.
Thus, of course, the Annavajjala publication does not
describe or suggest or otherwise “disclose” using “a power
delay profile to detect pilot signals in the communication
channel.”

Id. at 7.
We are persuaded by Appellant’s arguments because the Examiner
has not sufficiently shown that either Kangas or Annavajjala teaches the
claimed use of the “power delay profile” or the “matching pursuit” as recited
in the disputed limitation. We agree that Kangas does not teach or suggest
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the claimed PDP or MDP. Regarding the Examiner’s finding in the Answer
that Kangas’ “correlation” is MDP, we are persuaded by Appellant’s
argument that correlation and MDP are two separate activities. The
Annavajjala recitation to PDP and MP are to contexts significantly different
from the disputed limitation. In Annavajjala, PDP is not available at the
receiver, and Annavajjala does not utilize PDP in characterizing the channel
and instead assumes PDP is a constant value. Annavajjala ¶¶ 26, 30.
Additionally, the Examiner’s determination that PDP can be interpreted to
include the Annavajjala non-real value PDP is unreasonably broad as PDP is
described in the Specification as absolute value squared from the correlators,
and the phase information is removed. Spec. ¶ 61. The Examiner’s
interpretation is inconsistent with the claim and the Specification. During
prosecution, claims must be given their broadest reasonable interpretation
when reading claim language in light of the Specification as it would have
been interpreted by one of ordinary skill in the art. In re Am. Acad. of Sci.
Tech. Ctr., 367 F.3d 1359, 1364 (Fed. Cir. 2004).
Therefore, we do not sustain the rejection3 of claim 1, independent
claims 17 and 22 which include the disputed limitation, and dependent
claims 2–4, 8–10, 14, 20, and 21. Cf. In re Fritch, 972 F.2d 1260, 1266
(Fed. Cir. 1992).
Because our decision with regard to the disputed limitation is
dispositive of the rejections made, we do not address additional arguments
raised by Appellant.

3 See footnote 2. The Examiner states claims 5, 11, 15, 22, and 24–31 are
allowable. Ans. 46. Appellant argues claim 16 is also allowable as it
depends from allowable claim 15. Reply Br. 2.
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Application 14/811,507
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DECISION SUMMARY
In summary:

Claims
Rejected
35 U.S.C.
§
References/Basis Affirmed Reversed
1–6, 8–12,
14–17, 20–22,
24–31
103(a) Kangas,
Annavajjala
1–6, 8–12,
14–17, 20–22,
24–31

REVERSED