Prosecution Insights
Last updated: April 19, 2026
Application No. 18/697,601

DIGITAL SIGNAL PROCESSING CIRCUIT, METHOD, RECEIVER, AND COMMUNICATION SYSTEM

Non-Final OA §103§112
Filed
Apr 01, 2024
Examiner
KRETZER, CASEY L
Art Unit
2635
Tech Center
2600 — Communications
Assignee
NEC Corporation
OA Round
1 (Non-Final)
87%
Grant Probability
Favorable
1-2
OA Rounds
2y 2m
To Grant
99%
With Interview

Examiner Intelligence

Grants 87% — above average
87%
Career Allow Rate
608 granted / 700 resolved
+24.9% vs TC avg
Moderate +12% lift
Without
With
+12.2%
Interview Lift
resolved cases with interview
Fast prosecutor
2y 2m
Avg Prosecution
29 currently pending
Career history
729
Total Applications
across all art units

Statute-Specific Performance

§101
5.5%
-34.5% vs TC avg
§103
45.9%
+5.9% vs TC avg
§102
15.8%
-24.2% vs TC avg
§112
28.3%
-11.7% vs TC avg
Black line = Tech Center average estimate • Based on career data from 700 resolved cases

Office Action

§103 §112
DETAILED ACTION Notice of Pre-AIA or AIA Status The present application, filed on or after March 16, 2013, is being examined under the first inventor to file provisions of the AIA . Information Disclosure Statement The information disclosure statement(s) (IDS) submitted on 04/01/2024 is/are being considered by the Examiner. Priority Receipt is acknowledged of certified copies of papers required by 37 CFR 1.55. Specification The title of the invention is not descriptive. A new title is required that is clearly indicative of the invention to which the claims are directed. Claim Objections Claim 7 is objected to because of the following informalities: “the” is missing in front of “at least one processor”. Claim 13 is objected to because of the following informalities: an “and” should be after line 3. Appropriate correction is required. Claim Rejections - 35 USC § 112 The following is a quotation of 35 U.S.C. 112(b): (b) CONCLUSION.—The specification shall conclude with one or more claims particularly pointing out and distinctly claiming the subject matter which the inventor or a joint inventor regards as the invention. The following is a quotation of 35 U.S.C. 112 (pre-AIA ), second paragraph: The specification shall conclude with one or more claims particularly pointing out and distinctly claiming the subject matter which the applicant regards as his invention. Claims 1-19 are rejected under 35 U.S.C. 112(b) or 35 U.S.C. 112 (pre-AIA ), second paragraph, as being indefinite for failing to particularly point out and distinctly claim the subject matter which the inventor or a joint inventor (or for applications subject to pre-AIA 35 U.S.C. 112, the applicant), regards as the invention. Regarding independent claims 1, 9, and 19, each claim recites an adaptive equalizer to “multiply each of the input signals indicating the real component and the imaginary component of the first polarization and the input signals indicating the real component and the imaginary component of the second polarization by a complex impulse response, to add the signals each multiplied by the complex impulse response”. (emphasis added) Later in the claim, the adaptive equalizer is further recited to “multiply each of signals indicating phase conjugates of the real component and the imaginary component of the first polarization input and signals indicating phase conjugates of the real component and the imaginary component of the second polarization input by a complex impulse response, to add the signals each multiplied by the complex impulse response”. (emphasis added) However, the final clause of the claim recites a processor to “update the phase rotation for the carrier phase compensation and the complex impulse response that is multiplied by the adaptive equalizer”. Since there are two instances of complex impulse response previously recited, there is confusion on which of the two previous recitations the final recitation refers to or if it is to both. Dependent claim 7 also contains an instance of “the complex impulse response” with the same lack of clarity. Dependent claims 4, 11, and 15 exacerbate this issue by introducing four new instances of “a complex impulse response” then twice refers to “the complex impulse response”. One of ordinary skill would find which of the previous complex impulse responses are being referred to. Dependent claims 2, 3, 5, 6, 8, 10, 12-14, and 16-18 do not cure the independent claims of this issue and are similarly rejected. Claim Rejections - 35 USC § 103 In the event the determination of the status of the application as subject to AIA 35 U.S.C. 102 and 103 (or as subject to pre-AIA 35 U.S.C. 102 and 103) is incorrect, any correction of the statutory basis (i.e., changing from AIA to pre-AIA ) for the rejection will not be considered a new ground of rejection if the prior art relied upon, and the rationale supporting the rejection, would be the same under either status. The following is a quotation of 35 U.S.C. 103 which forms the basis for all obviousness rejections set forth in this Office action: A patent for a claimed invention may not be obtained, notwithstanding that the claimed invention is not identically disclosed as set forth in section 102, if the differences between the claimed invention and the prior art are such that the claimed invention as a whole would have been obvious before the effective filing date of the claimed invention to a person having ordinary skill in the art to which the claimed invention pertains. Patentability shall not be negated by the manner in which the invention was made. Claim(s) 1, 8, 9, and 13 is/are rejected under 35 U.S.C. 103 as being unpatentable over Kobayashi et al, WO 2020/175014 A1 (citations will be given to U.S. Publication No. 2022/0149974 which is an official translation) in view of Zhou et al, U.S. Publication No. 2016/0142149. Regarding claim 9, Kobayashi teaches a receiver (see Kobayashi Figure 1, receiver 50) comprising: a detector (see Figure 1, optical front end 520) configured to coherently receive (see paragraph [0022]) a polarization-multiplexed optical signal transmitted from a transmitter via a transmission line (see Figure 1, output from transmitter 10 to path 30 and paragraph [0030]); and a digital signal processing circuit (see Figure 1, unit 530 and paragraph [0029]) configured to perform equalization signal processing on the reception signal coherently received (see Figure 1, adaptive equalization unit 534), wherein the digital signal processing circuit includes a chromatic dispersion compensation filter (see Figure 1, wavelength dispersion compensation unit 533) configured to multiply each of a real component and an imaginary component of each of a first polarization and a second polarization of the reception signal by a filter coefficient that compensates for chromatic dispersion (see Figure 2, which shows details of unit 533 of Figure 1, inputs XI, XQ, YI, YQ to Hr and Hcd units and paragraph [0050]), an adaptive equalizer (see Figure 1, adaptive equalization unit 534) configured to receive input of signals indicating the real component and the imaginary component of the first polarization output from the chromatic dispersion compensation filter and signals indicating the real component and the imaginary component of the second polarization output from the chromatic dispersion compensation filter (see Figure 2, which shows details of unit 534 of Figure 1, “complex signals” input into “adaptive equalization”) to multiply each of the input signals indicating the real component and the imaginary component of the first polarization and the input signals indicating the real component and the imaginary component of the second polarization by a complex impulse response (see Figure 2, XI, XQ, YI, YQ outputs to two different “h” units and paragraph [0052]), to add the signals each multiplied by the complex impulse response (see Figure 2, outputs from respective “h” units to the first addition unit for the X polarization and to the third addition unit for the Y polarization), and to subject the added signals to phase rotation for carrier phase compensation including a frequency offset for each polarization (see Figure 2, output of first addition unit to first multiplier and third addition unit to the third multiplier and paragraph [0052]), and further configured to multiply each of signals indicating phase conjugates of the real component and the imaginary component of the first polarization input and signals indicating phase conjugates of the real component and the imaginary component of the second polarization input by a complex impulse response (see Figure 2, “conjugates” of XI, XQ, YI, and YQ to two different “h” units” and paragraph [0052]), to add the signals each multiplied by the complex impulse response (see Figure 2, outputs from respective “h” units to the second addition unit for the conjugate of the X polarization and to the fourth addition unit for the conjugate of the Y polarization), to subject the added signals to rotation reverse to the phase rotation for the carrier phase compensation for each polarization (see Figure 2, outputs of the second addition unit to the second multiplier and of the fourth addition unit to the fourth multiplier and paragraph [0052]), to add, for each polarization, the signals subjected to the phase rotation for the carrier phase compensation and the signals subjected to the rotation reverse to the phase rotation for the carrier phase compensation, and to output the added signals (see Figure 2, outputs from first two multipliers to addition unit which produces Xrsig and outputs from bottom two multipliers to addition unit which outputs Yrisg), and at least one memory storing instructions; and at least one processor configured to execute the instructions to (see claim 5) update the phase rotation for the carrier phase compensation and the complex impulse response that is multiplied by the adaptive equalizer (see paragraph [0054]). Kobayashi does not expressively teach wherein the updates are made by use of an output of the adaptive equalizer. However, Zhou in a similar invention in the same field of endeavor teaches a receiver (see Zhou Figure 2b and paragraph [0010]) comprising an adaptive equalizer (see Figure 3, which is an embodiment of the digital signal processor of Figure 2b per paragraph [0011], adaptive equalizer 330) configured for updates to various coefficients (see paragraph [0025]) as taught in Zhou wherein the updates are made by use of an output of the adaptive equalizer (see Figure 3, feedback from outputs of adaptive equalizer 330 to processes 392, 394 and paragraph [0025]). One of ordinary skill in the art before the effective filing date of the invention would have found it obvious as a matter of simple substitution to replace the method of updating values taught in Kobayashi with the method of using output from an adaptive equalizer as taught in Zhou, to yield the predictable results of accurately determining updated values for compensation. Independent claims 1 and 19 recite similar limitations as claim 9, and are rejected under similar rationale. Regarding claim 8, Kobayashi in view of Zhou teaches all the limitations of claim 1, and further teaches wherein the adaptive equalizer is configured to compensate for distortion produced in the transmitter (see Kobayashi paragraph [0063]), distortion produced in the receiver (see Kobayashi paragraph [0058]), polarization mode dispersion, frequency offset, or phase noise of a light source. Regarding claim 13, Kobayashi in view of Zhou teaches communication system comprising: a transmitter configured to transmit a polarization-multiplexed optical signal via a transmission line (see Kobayashi Figure 1, transmitter 10 sending signal over line 30 and paragraph [0035]); the receiver according to claim 9 (see above). Claim(s) 2, 3, 10, and 14 is/are rejected under 35 U.S.C. 103 as being unpatentable over Kobayashi et al, WO 2020/175014 A1 (citations will be given to U.S. Publication No. 2022/0149974 which is an official translation) in view of Zhou et al, U.S. Publication No. 2016/0142149 and Kobayashi et al, “35-Tb/s C-band Transmission over 800 km Employing 1-Tb/s PS-64QAM signals enhanced by Complex 8 × 2 MIMO Equalizer” (published in 2019 Optical Fiber Communications Conference and Exhibition (OFC), March 2019, hereafter referred to as Kobayashi 2). Regarding claim 10, Kobayashi in view of Zhou teaches all the limitations of claim 9, and further teaches wherein the adaptive equalizer includes a complex widely linear (WL) MIMO filter (see Kobayashi Figure 2, and paragraph [0049] indicates the MIMO nature. WL is implied by paragraph [0039]). Kobayashi in view of Zhou does not expressively teach wherein the complex MIMO filter is a complex 8x2 MIMO filter. However, Kobayashi 2 in a similar invention in the same field of endeavor teaches an adaptive equalizer comprising a complex MIMO filter (see Kobayashi 2, Figure 2 and Abstract) configured to act on a real and imaginary component of a first and second polarization (see Figure 2, XI, XQ, YI, YQ inputs) and phase conjugates of a real and imaginary component of a first and second polarization (see Figure 2, “conj” and section 2, first paragraph) as taught in Kobayashi in view of Zhou as taught in Kobayashi in view of Zhou wherein the complex MIMO filter is a complex 8x2 MIMO filter (see caption for Figure 2). One of ordinary skill in the art before the effective filing date of the invention would have found it obvious as a matter of simple substitution to replace the MIMO filter of Kobayashi in view of Zhou with that of Kobayashi 2 to yield the predictable results of successfully equalizing the polarizations. Claim 2 recites similar limitations as claim 10, and is rejected under similar rationale. Regarding claim 3, Kobayashi in view of Zhou and Kobayashi 2 teaches all the limitations of claim 2, and further teaches wherein the 8x2 WL MIMO filter is a WL filter (see Kobayashi paragraph [0039] as combined with Kobayashi 2, Figure 2) configured to receive input of a complex signal indicating the real component and a complex signal indicating the imaginary component of the first polarization, a complex signal indicating the real component and a complex signal indicating the imaginary component of the second polarization (see Kobayashi 2, Figure 2, XI, XQ, YI, YQ inputs), a complex signal indicating the phase conjugate of the real component and a complex signal indicating the phase conjugate of the imaginary component of the first polarization, and a complex signal indicating the phase conjugate of the real component and a complex signal indicating the phase conjugate of the imaginary component of the second polarization (see Kobayashi 2, Figure 2, “conj” for each signal), and to output a complex signal of the first polarization and a complex signal of the second polarization (see Kobayashi 2, Figure 2, X-pol and Y-pol outputs, wherein the operations performed in the equalizer implies complex outputs from complex inputs). Regarding claim 14, Kobayashi in view of Zhou teaches all the limitations of claim 13, and further teaches wherein the adaptive equalizer includes a complex widely linear (WL) MIMO filter (see Kobayashi Figure 2, and paragraph [0049] indicates the MIMO nature. WL is implied by paragraph [0039]). Kobayashi in view of Zhou does not expressively teach wherein the complex MIMO filter is a complex 8x2 MIMO filter. However, Kobayashi 2 in a similar invention in the same field of endeavor teaches an adaptive equalizer comprising a complex MIMO filter as taught in Kobayashi in view of Zhou (see Figure 2 and Abstract) as taught in Kobayashi in view of Zhou wherein the complex MIMO filter is a complex 8x2 MIMO filter (see caption for Figure 2). One of ordinary skill in the art before the effective filing date of the invention would have found it obvious as a matter of simple substitution to replace the MIMO filter of Kobayashi in view of Zhou with that of Kobayashi 2 to yield the predictable results of successfully equalizing the polarizations. Claim(s) 7 is/are rejected under 35 U.S.C. 103 as being unpatentable over Kobayashi et al, WO 2020/175014 A1 (citations will be given to U.S. Publication No. 2022/0149974 which is an official translation) in view of Zhou et al, U.S. Publication No. 2016/0142149 and Arikawa et al, “Transmitter and receiver impairment monitoring using adaptive multi-layer linear and widely linear filter coefficients controlled by stochastic gradient descent” (published at Optics Express, Vol. 29, Issue 8, pages 11548-11561, April 2021, provided by Applicant as an IDS submission on 04/01/2024). Regarding claim 7, Kobayashi in view of Zhou teaches all the limitations of claim 1, but does not expressively teach at least one processor is further configured to execute the instructions to estimate at least one of distortion produced in the transmitter or distortion produced in the receiver, based on the complex impulse response in the adaptive equalizer. However, Arikawa in a similar invention in the same field of endeavor teaches a system comprising a transmitter, receiver (see Arikawa section 2.2, first paragraph), and an adaptive equalizer (see Figure 2 and caption) using a complex impulse response (see section 2.2, second paragraph, “All the filters are assumed finite impulse response filters with half-symbol spaced”) as taught in Kobayashi in view of Zhou wherein the system is further configured to estimate at least one of distortion produced in the transmitter or distortion produced in the receiver, based on the complex impulse response in the adaptive equalizer (see section 2.2, final paragraph). One of ordinary skill in the art before the effective filing date of the invention would have found it obvious to combine the teaching of monitoring transmitter and receiver distortion based on complex impulse response in an adaptive equalizer as taught in Arikawa with the system taught in Kobayashi in view of Zhou, the motivation being to quickly know where a dramatic increase in distortion is occurring in the system thereby remedying it rapidly. Allowable Subject Matter Claims 4-6, 11, 12, and 15-18 would be allowable if rewritten to overcome the rejection(s) under 35 U.S.C. 112(b) or 35 U.S.C. 112 (pre-AIA ), 2nd paragraph, set forth in this Office action and to include all of the limitations of the base claim and any intervening claims. Conclusion Any inquiry concerning this communication or earlier communications from the examiner should be directed to CASEY L KRETZER whose telephone number is (571)272-5639. The examiner can normally be reached M-F 10:00-7:00 PM Pacific Time. Examiner interviews are available via telephone, in-person, and video conferencing using a USPTO supplied web-based collaboration tool. To schedule an interview, applicant is encouraged to use the USPTO Automated Interview Request (AIR) at http://www.uspto.gov/interviewpractice. If attempts to reach the examiner by telephone are unsuccessful, the examiner’s supervisor, David Payne can be reached at (571)272-3024. The fax phone number for the organization where this application or proceeding is assigned is 571-273-8300. Information regarding the status of published or unpublished applications may be obtained from Patent Center. Unpublished application information in Patent Center is available to registered users. To file and manage patent submissions in Patent Center, visit: https://patentcenter.uspto.gov. Visit https://www.uspto.gov/patents/apply/patent-center for more information about Patent Center and https://www.uspto.gov/patents/docx for information about filing in DOCX format. For additional questions, contact the Electronic Business Center (EBC) at 866-217-9197 (toll-free). If you would like assistance from a USPTO Customer Service Representative, call 800-786-9199 (IN USA OR CANADA) or 571-272-1000. /CASEY L KRETZER/Primary Examiner, Art Unit 2635
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Prosecution Timeline

Apr 01, 2024
Application Filed
Mar 04, 2026
Non-Final Rejection — §103, §112 (current)

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Prosecution Projections

1-2
Expected OA Rounds
87%
Grant Probability
99%
With Interview (+12.2%)
2y 2m
Median Time to Grant
Low
PTA Risk
Based on 700 resolved cases by this examiner. Grant probability derived from career allow rate.

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