Ex Parte Chang et al

Board of Patent Appeals and Interferences

Apr 29, 2010

10228165 (B.P.A.I. Apr. 29, 2010)

UNITED STATES PATENT AND TRADEMARK OFFICE
____________________

BEFORE THE BOARD OF PATENT APPEALS
AND INTERFERENCES
____________________

Ex parte LI FUNG CHANG, NELSON SOLLENBERGER,
and BAOGUO YANG
____________________

Appeal 2009-006053
Application 10/228,1651
Technology Center 2400
____________________

Decided: April 30, 2010
____________________

Before ROBERT E. NAPPI, MAHSHID D. SAADAT,
and MARC S. HOFF, Administrative Patent Judges.

HOFF, Administrative Patent Judge.

DECISION ON APPEAL

1 The real party in interest is Broadcom Corporation.
Appeal 2009-006053
Application 10/228,165

STATEMENT OF THE CASE
Appellants appeal under 35 U.S.C. § 134(a) from a Final Rejection of
claims 1-24. We have jurisdiction under 35 U.S.C. § 6(b).
We reverse.
Appellants’ invention relates to a method and apparatus for acquiring
and verifying a code used by a base station, wherein acquisition time is
reduced and circuitry simplified by performing a Phase I and Phase II
acquisitions in series, which are in parallel with a Phase III code acquisition
and a verification stage implemented in series. The Phase III code
acquisition is implemented by despreading the input signal using each of the
possible codes in a code group. An estimation of the frequency offset
between the base station and the terminal's local reference is used to correct
the phase of the despread signals, which are coherently and non-coherently
integrated. The largest accumulated value corresponds to the code used by
the base station. The code is verified by despreading the received signal,
applying a frequency correction, and demodulating. The demodulated
output is a series of symbols, and a count of these symbols verifies the
acquired code (Abstract).
Claim 1 is exemplary:
1. A method for processing a wireless signal, comprising:
a) determining a plurality of time-slot boundaries for a current portion
of the wireless signal using a primary synchronizing signal within the
wireless signal; and
b) determining a plurality of frame boundaries and a code group
associated with the current portion and used by a base station for
transmitting the wireless signal, using a secondary synchronizing signal
within the wireless signal;
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c) determining a first code used by the base station associated with a
previous portion of the wireless signal, using a common pilot channel signal
within the wireless signal; and
d) verifying whether the first code is the code used by the base station,
wherein a) and b) are performed serially, wherein c) and d) are performed
serially, and wherein a) and b) are performed concurrently with respect to c)
and d).

The prior art relied upon by the Examiner in rejecting the claims on
appeal is:
Chennakeshu US 6,134,286 Oct. 17, 2000
Chen US 6,775,318 B2 Aug. 10, 2004
Sriram US 6,831,929 B1 Dec. 14, 2004

Claims 1, 2, and 20 stand rejected under 35 U.S.C. 5 103(a) as being
unpatentable over Sriram in view of Chen.
Claims 3-6 stand rejected under 35 U.S.C. § 103(a) as being
unpatentable over Sriram in view of Chen and Chennakeshu.
Claims 7-19 stand rejected under 35 U.S.C. § 103(a) as being
unpatentable over Sriram in view of Chennakeshu.
Claims 21-24 stand rejected under 35 U.S.C. § 103(a) as being
unpatentable over Sriram in view of Chen and Chennakeshu.
Rather than repeat the arguments of Appellants or the Examiner, we
make reference to the Appeal Brief (filed October 29, 2007), the Reply Brief
(filed March 24, 2008), and the Examiner’s Answer (mailed January 24,
2008) for their respective details.

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ISSUES
The Examiner finds that the verification process is inherent since
without properly identifying and verifying the thirty-two long code
sequence, the sequence could not be demodulated appropriately (Ans. 20-
21). The Examiner finds that Chennakeshu discloses that the received
samples are multiplied with conjugates of the coarse frequency offset
estimates which is equivalent to multiplying each series of symbols in a first
plurality of symbols with frequency offset estimation signals (Ans. 26). The
Examiner finds that the coarse frequency correction disclosed in
Chennakeshu oscillates back and forth towards the correct frequency using
the second frequency offset estimation to frequency adjust the first
frequency adjusted signal (Ans. 30).
Appellants contend that there is simply no support in Sriram that once
a code is identified, it is also verified (App. Br. 15, Reply Br. 4). Appellants
contend that Chennakeshu discloses that the received samples are multiplied
by conjugate values, rather than multiplying each series of symbols with a
frequency offset estimation signal selected from a plurality of frequency
offset estimation signals as recited (App. Br. 30-31). Appellants contend
that Chennakeshu discloses coarse frequency correction using signal rotation
and using only a single coarse frequency offset estimate (App. Br. 30).
Appellants’ contentions present us with the following three issues:
1. Does Sriram disclose that the detected first code used by the base
station is verified?
2. Does Chennakeshu disclose that the samples which represent a
series of symbols are multiplied by the frequency offset estimation signal?
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3. Does Chennakeshu disclose a first and a second frequency offset
correction circuit?

FINDINGS OF FACT
The following Findings of Fact (FF) are shown by a preponderance of
the evidence.
The Invention
1. According to Appellants, the invention relates to a method and
apparatus for acquiring and verifying a code used by a base station, wherein
acquisition time is reduced and circuitry simplified by performing a Phase I
and Phase II acquisitions in series, which are in parallel with a Phase III
code acquisition and a verification stage implemented in series. The Phase
III code acquisition is implemented by despreading the input signal using
each of the possible codes in a code group. An estimation of the frequency
offset between the base station and the terminal's local reference is used to
correct the phase of the despread signals, which are coherently and non-
coherently integrated. The largest accumulated value corresponds to the
code used by the base station. The code is verified by despreading the
received signal, applying a frequency correction, and demodulating. The
demodulated output is a series of symbols, and a count of these symbols
verifies the acquired code (Abstract).
Sriram
2. Sriram discloses that when a mobile unit selects a base station
from several candidate base stations at power-up and during soft handoff
within a cell, selection requires cell acquisition made of each base station to
develop a candidate list. The cell acquisition includes three stages. The first
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stage includes detecting a primary synchronization channel (PSC) code from
a serial pseudorandom noise (PN) sequence. The second stage uses the time
of the PSC code to extract a code from a secondary synchronization channel
(SSC). This SSC code includes sixteen code sequences and is transmitted
simultaneously with the PSC code. The SSC code, however, is unique to
each base station. Furthermore, the order of the SSC code sequences
identifies the position within the frame where the PSC code was identified
during first-stage acquisition and a group of thirty-two long codes used by
the base station. Finally, in the third stage, the mobile unit must identify the
one of thirty-two long code sequences to demodulate the received signal
(col. 4, l. 55-col. 5, l. 12).
Chen
3. Chen discloses the mobile terminal determines the exact
primary scrambling code used by the found base station. The primary
scrambling code is typically identified through symbol-to-symbol correlation
over the Common Pilot Channel (hereinafter CPICH) with all codes within
the code group identified in the second step (col. 2, ll. 35-42).
Chennakeshu
4. Chennakeshu discloses a coarse frequency corrector wherein an
input signal is sampled a predetermined number of times, e.g., four times per
bit, to provide an input sample stream. Since each bit is sampled four times,
it is possible to take the first sample from each bit to form a first set of
samples, the second sample from each bit to form a second set of samples,
and so on. A differential detector 22 to differentially detect each set of
samples to provide four sets of differential samples. The coarse frequency
corrector averages and scales the differential samples using an averager and
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a scaler to provide a coarse frequency offset estimate. At block 28, the
conjugate of the coarse frequency offset estimate is formed to prepare the
estimate for use in correcting the frequency offset at multiplier. That is, by
multiplying the received samples with the conjugates of the coarse
frequency offset estimates, the input sample stream is rotated back toward
the correct (tuned) frequency (Figs. 1 and 2, col. 4, ll. 6-39, col. 4, l. 67-col.
5, l. 5).
5. Chennakeshu discloses that the coarse frequency corrector
rotates the pre-filtered signal according to a coarse frequency offset estimate
to provide a coarsely (frequency) corrected signal (col. 3, ll. 41-47).

PRINCIPLES OF LAW
On the issue of obviousness, the Supreme Court has stated that “the
obviousness analysis cannot be confined by a formalistic conception of the
words teaching, suggestion, and motivation.” KSR Int’l Co. v. Teleflex Inc.,
550 U.S. 398, 419 (2007). Further, the Court stated “[t]he combination of
familiar elements according to known methods is likely to be obvious when
it does no more than yield predictable results.” Id. at 416. “One of the ways
in which a patent’s subject matter can be proved obvious is by noting that
there existed at the time of the invention a known problem for which there
was an obvious solution encompassed by the patent’s claims.” Id. at 419-
420.
The determination of obviousness must consider, inter alia, whether a
person of ordinary skill in the art would have been motivated to combine the
prior art to achieve the claimed invention and whether there would have
been a reasonable expectation of success in doing so. Brown & Williamson
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Tobacco Corp. v. Philip Morris Inc., 229 F.3d 1120, 1125 (Fed. Cir. 2000).
Where the teachings of two or more prior art references conflict, the
Examiner must weigh the power of each reference to suggest solutions to
one of ordinary skill in the art, considering the degree to which one
reference might accurately discredit another. In re Young, 927 F.2d 588,
591 (Fed. Cir. 1991). If the proposed modification would render the prior
art invention being modified unsatisfactory for its intended purpose, then
there is no suggestion or motivation to make the proposed modification. In
re Gordon, 733 F.2d 900, 902 (Fed. Cir. 1984). Further, our reviewing court
has held that “[a] reference may be said to teach away when a person of
ordinary skill, upon reading the reference, would be discouraged from
following the path set out in the reference, or would be led in a direction
divergent from the path that was taken by the applicant.” In re Gurley, 27
F.3d 551, 553 (Fed. Cir. 1994); Para-Ordnance Mfg., Inc. v. SGS Importers
Int’l., Inc., 73 F.3d 1085, 1090 (Fed. Cir. 1995).
Under the doctrine of inherency, if a claimed element is not expressly
disclosed in a prior art reference, the teachings of the reference nevertheless
anticipates the claim if the missing element is necessarily present in the
reference, and it would be so recognized by skilled artisans. Rosco, Inc. v.
Mirror Lite Co., 304 F.3d 1373, 1380 (Fed. Cir. 2002). In the context of
anticipation and obviousness, the missing element must be necessarily
present in the prior art—not merely probably or possibly present. Id.
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ANALYSIS
Claims 1, 2, and 20
Independent claim 1 recites “verifying whether the first code is the
code used by the base station.”
Independent claim 20 recites “a fourth circuit configured to verify that
the common pilot channel signal within the previous portion of the received
wireless signal is encoded using the first code.”
The Examiner finds that Sriram teaches that in the third stage
acquisition, the mobile unit identifies one of thirty-two long code sequences
to demodulate the received signal (Ans. 20). The Examiner finds that the
verification process is inherent to the operation performed in the third stage
acquisition (Ans. 20). The Examiner reasons that without properly
identifying and verifying the thirty-two long code sequence, the signal could
not be demodulated appropriately (Ans. 20-21). In the case of receipt of an
incorrect code sequence, the Examiner concludes that mobile unit would not
generate the corresponding correct resultant, since a false code cannot be
demodulated (Ans. 21). The Examiner finds further that after identification
of only one of thirty-two long code sequences, a match must be found before
the demodulation can begin since demodulation will not begin with a false
code; thereby verification is inherently part of the identification process. As
such, the Examiner concludes that Sriram discloses “verifying whether the
first code is the code used by the base station” (Ans. 21).
Appellants contend neither Sriram nor Chen discloses or suggests
"verifying whether the first code is the code used by the base station" (App.
Br. 15). Appellants contend that there is simply no support in Sriram that
once a code is identified, it is also verified (App. Br. 15, Reply Br. 4).
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Appellants contend that “identification” is different from “verification
and verification is not necessarily included in identification” (App. Br.
16). Appellants contend that once the long code sequence is selected in the
third-stage acquisition process of Sriram, a subsequent error correction
technique may need to be used in the event of mis-detection or mis-
identification (Reply Br. 5).
We agree with Appellants that a verification step is not taught in
either Sriram or Chen (App. Br. 15). Specifically, Sriram discloses cell
acquisition, which includes three stages (FF 2). The first stage includes
detecting a primary synchronization channel (PSC) code from a serial
pseudorandom noise (PN) sequence (FF 2). The second stage uses the time
of the PSC code to extract a code from a secondary synchronization channel
(SSC) (FF 2). Finally, in the third stage, the mobile unit must identify the
one of thirty-two long code sequences to demodulate the received signal (FF
2). Chen discloses the use of the Common Pilot Channel to determine the
primary scrambling code used by the found base station (FF 3). Both Sriram
and Chen are silent as to a verification step in the process of cell acquisition.
Although we agree with the Examiner’s finding that a mobile unit
cannot generate a corresponding correct resultant when an incorrect code
sequence is present (since a false code cannot be demodulated) (Ans. 21),
we do not agree that the identification step of cell acquisition would
inherently include a verification step since both references are silent
regarding the presence of a verification step. We find that the Examiner has
not provided a basis in fact or technical reasoning to reasonably support the
determination that the alleged inherent characteristic of a verification step
necessarily flows from the teachings of Sriram and Chen.
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We find that the combined teachings of Sriram and Chen do not
disclose all the limitations of independent claims 1 and 20. Thus, we find
error in the Examiner’s rejection of claims 1, 2, and 20 under 35 U.S.C. §
103(a) as unpatentable over Sriram in view of Chen, and we will not sustain
the rejection.
Claims 3-6
As noted supra, we reversed the rejection of claim 1 from which
claims 3-6 depend. We have reviewed Chennakeshu (the additional
reference applied by the Examiner to reject these claims), and find that the
cited reference does not teach the limitations deemed to be absent from
Sriram and Chen.
We therefore reverse the Examiner’s rejections of claims 3-6 under 35
U.S.C. § 103, for the same reasons expressed with respect to the § 103
rejection of parent claim 1, supra.
Claims 7-11
Independent claim 7 recites “multiplying each series of symbols in the
first plurality of series of symbols with a frequency offset estimation signal
from the plurality of frequency offset estimation signals to generate a second
plurality of series of symbols."
The Examiner finds that Chennakeshu discloses that the received
samples are multiplied with conjugates of the coarse frequency offset
estimates which is equivalent to multiplying each series of symbols in a first
plurality of symbols with frequency offset estimation signals (Ans. 26).
Appellants contend that the combination of Sriram and Chennakeshu
does not teach "multiplying each series of symbols in the first plurality of
series of symbols with a frequency offset estimation signal from the
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plurality of frequency offset estimation signals to generate a second plurality
of series of symbols" (App. Br. 29). Appellants contend that Chennakeshu
discloses that the received samples are multiplied by conjugate values, rather
than multiplying each series of symbols with a frequency offset estimation
signal selected from a plurality of frequency offset estimation signals as
recited (App. Br. 30-31, FF 4).
We agree with the Appellants that multiplying the received samples
with conjugate values of the frequency offset estimation signals is not the
same as multiplying with the frequency offset estimation signals as recited in
the claim (FF 4). Conjugate or complex conjugation by definition implies
that the imaginary part of a complex number is multiplied by −1. Thereby,
the conjugate values of the frequency offset estimation signals are not the
same as the frequency offset estimation signals without conjugation.
We find that the combined teachings of Sriram and Chennakeshu do
not teach all the limitations of independent claim 7. Thus, we find error in
the Examiner’s rejection of claims 7-11 under 35 U.S.C. § 103(a) as
unpatentable over Sriram in view of Chennakeshu, and we will not sustain
the rejection.
Claims 12-15
Independent claim 12 recites “verifying the code used by the base
station.”
Similar to claim 1, as noted supra, the Examiner finds that Sriram
teaches in the third stage acquisition, the mobile unit identifies the one of
thirty-two long code sequences to demodulate the received signal (Ans. 28).
The Examiner concludes that the verification step is inherent to the operation
performed in the third stage acquisition (Ans. 28).
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Appellants contend that Sriram only discloses a three-stage cell
acquisition process which does not include verification by using despreading
as recited in the claim (App. Br. 37).
As noted supra, we reversed the rejection of claim 1 which includes
the claimed verification step.
We therefore reverse the Examiner’s rejections of claims 12-15 under
35 U.S.C. § 103, for the same reasons expressed with respect to the § 103
rejection of claim 1, supra.
Claims 16-19
Independent claim 16 recites a first and a second frequency correction
circuit.
The Examiner finds that although Sriram does not disclose using a
first series of symbols to generate a first frequency offset (a first frequency
offset correction circuit), Chennakeshu teaches a synchronization technique
and system for radio communications utilizing Coarse Frequency Correction
and Fine Frequency Correction which output the synchronized signal to a
demodulator (Ans. 14). In addition, the Examiner finds that Chennakeshu
teaches using the second series of symbols to generate a second frequency
offset estimation (using a second frequency offset correction circuit) (Ans.
30). The Examiner finds that the coarse frequency corrector of
Chennakeshu utilizes a set of samples which thereby comprises a set of
frequency offsets (Ans. 30). The Examiner reasons that coarse frequency
correction of Chennakeshu is done in an iterative manner; thereby
generating a series of frequency offset estimation signals which correspond
to the first series of symbols (Ans. 30). The Examiner concludes that in this
manner the coarse frequency correction oscillates back and forth towards the
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correct frequency (using the second frequency offset estimation to frequency
adjust the first frequency adjusted signal) (Ans. 30). The Examiner finds
that this interpretation of the claim is based upon a broad literal reasonable
interpretation of the claim (Ans. 30). The Examiner finds that the claim
does not preclude such an interpretation, because the claim limitations do
not recite the period in time which the estimation signals are generated
(instantaneously or periodic) (Ans. 30).
Appellants contend the combination of Sriram and Chennakeshu does
not disclose or suggest at least the limitation of "a first frequency correction
circuit configured to adjust the frequency of an input signal using a
frequency offset estimation symbol selected from a plurality of frequency
offset estimation symbols” (App. Br. 42). Appellants contend that
Chennakeshu discloses coarse frequency correction using signal rotation and
using only a single coarse frequency offset estimate (App. Br. 43, FF 5).
We agree with Appellants that the combination of Sriram and
Chennakeshu does not disclose a first frequency correction circuit, in
addition to a second frequency correction circuit as recited. Specifically,
Sriram discloses cell acquisition using three stages: a first stage that includes
detecting a primary synchronization channel (PSC) code from a serial
pseudorandom noise sequence; a second stage that uses the time of the PSC
code to extract a code from a secondary synchronization channel; and a third
stage, wherein the mobile unit must identify the one of thirty-two long code
sequences to demodulate the received signal (FF 2). Chennakeshu discloses
one coarse frequency corrector (FF 5). Chennakeshu is silent as to a first
and a second frequency correction circuit.
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We find that the combined teachings of Sriram and Chennakeshu do
not teach all the limitations of independent claim 16. Thus, we find error in
the Examiner’s rejection of claims 17-19 under 35 U.S.C. § 103(a) as
unpatentable over Sriram in view of Chennakeshu, and we will not sustain
the rejection.
Claims 21-24
As noted supra, we reversed the rejection of claim 20 from which
claims 21-24 depend. We have reviewed Chennakeshu (the additional
reference applied by the Examiner to reject these claims), and find that the
cited reference does not teach the limitations deemed to be absent from
Sriram and Chen.
We therefore reverse the Examiner’s rejections of claims 21-24 under
35 U.S.C. § 103, for the same reasons expressed with respect to the § 103
rejection of parent claim 20, supra.

CONCLUSIONS OF LAW
Sriram does not disclose that the detected first code used by the base
station is verified.
Chennakeshu does not disclose that the samples which represent a
series of symbols are multiplied by the frequency offset estimation signal.
Chennakeshu does not disclose a first and a second frequency offset
correction circuit.
ORDER
The Examiner’s rejection of claims 1-24 is reversed.
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REVERSED

ELD

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