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 .
Specification
The lengthy specification has not been checked to the extent necessary to determine the presence of all possible minor errors. Applicant’s cooperation is requested in correcting any errors of which applicant may become aware in the specification.
Claim Rejections - 35 USC § 112 – Scope of Enablement
The following is a quotation of 35 U.S.C. 112(a):
(a) IN GENERAL.—The specification shall contain a written description of the invention, and of the manner and process of making and using it, in such full, clear, concise, and exact terms as to enable any person skilled in the art to which it pertains, or with which it is most nearly connected, to make and use the same, and shall set forth the best mode contemplated by the inventor or joint inventor of carrying out the invention.
The following is a quotation of 35 U.S.C. 112 (pre-AIA ), first paragraph:
The specification shall contain a written description of the invention, and of the manner and process of making and using it, in such full, clear, concise, and exact terms as to enable any person skilled in the art to which it pertains, or with which it is most nearly connected, to make and use the same and shall set forth the best mode contemplated by the inventor of carrying out his invention.
Claims 1-11 and 13-21 are rejected under 35 U.S.C. 112(a) or 35 U.S.C. 112 (pre-AIA ), first paragraph, because the specification, while being enabling for a limited scope based on the teachings in the application, does not reasonably provide enablement for the full scope recited in the claims. The specification does not enable any person skilled in the art to which it pertains, or with which it is most nearly connected, to make and use the invention commensurate in scope with these claims.
MPEP 2164.08 states: “The Federal Circuit has repeatedly held that ‘the specification must teach those skilled in the art how to make and use the full scope of the claimed invention without ‘undue experimentation’.” In re Wright, 999 F.2d 1557, 1561, 27 USPQ2d 1510, 1513 (Fed. Cir. 1993).
Summary of the Rejection.
The independent claims have been amended to remove the structural elements (e.g., “optical modulation means” and “pilot addition means”) and to replace them with “memory” and a “processor” (see the amendment filed Nov. 20, 2023). The Examiner can find no teachings in the specification to make and use the claimed invention with a memory and processor substituted for the elements removed from the claim, and the Examiner can find no support in the prior art for such a substitution. As discussed in more detail below, the teachings of the application are not commensurate with the amended claims.
Scope of the Claims and Teachings of the Application.
Claim 1 recites (emphasis by Examiner):
An optical transmission apparatus comprising:
at least one memory storing instructions, and
at least one processor configured to execute the instructions to;
generate a first digital signal by adding a first pilot signal to a first data signal and generate a second digital signal by adding a second pilot signal to a second data signal; and
generate an optical modulation signal by
optically modulating the first digital signal with a first subcarrier included in a negative frequency band to a center frequency of a used frequency band,
optically modulate the second digital signal with a second subcarrier included in a positive frequency band to the center frequency of the used frequency band, and
transmit the optical modulation signal, wherein
the at least one processor configured to execute the instructions
not to transmit the second pilot signal during transmission of the first pilot signal, and
not to transmit the first pilot signal during transmission of the second pilot signal.
This is an apparatus claim with a scope that requires no more than a memory and processor to perform the recited functionality. In other words, the claim has a scope in which memory and a processor optically modulate signals, transmit the optical signals, and perform other functionality without any additional structure.
The present application at FIG. 5 appears teaches an optical transmission apparatus 11 that performs the functionality recited in the claim.
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This embodiment uses a pilot addition means 111 and the optical modulation means 112 to achieve the results recited in the claim. See, for example, the PG pub of the present application:
[0096] The pilot addition means 111 adds (inserts) a first pilot signal to a first data signal to generate a first digital signal, and adds (inserts) a second pilot signal to a second data signal to generate a second digital signal.
[0097] The optical transmission apparatus 11 may include data signal generation means for generating a data signal by performing processing such as encoding on the information to be transmitted. The data signal includes a first data signal and a second data signal. The pilot addition means is sometimes referred to as pilot insertion means. The first pilot signal and the second pilot signal are sometimes collectively referred to as a pilot signal. The pilot signal is a known signal required to reproduce the data signal.
[0098] The optical modulation means 112 optically modulates a digital subcarrier multiplexed signal as follows.
[0099] The optical modulation means 112 generates an optical modulation signal by optically modulating the first digital signal with the first subcarrier SC1 included in a negative frequency band to a center frequency of a used frequency band and optically modulating the second digital signal with the second subcarrier SC2 included in a positive frequency band to the center frequency of the used frequency band. Specifically, the optical modulation means 112 generates an optical modulation signal by optically modulating an inphase component SC1-I and a quadrature component SC1-Q of the first digital signal with the first subcarrier SC1, and optically modulating an inphase component SC2-I and a quadrature component SC2-Q of the second digital signal with the second subcarrier SC2. After that, the optical modulation means 112 transmits the generated optical modulation signal. The negative frequency band to the center frequency indicates a frequency band lower than the center frequency. The positive frequency band to the center frequency indicates a frequency band higher than or equal to the center frequency.
[0101] The optical modulation means 112 may optically modulate digital signals by means of a Mach-Zender (MZ) modulator.
[0102] The pilot addition means 111 does not transmit the second pilot signal during the transmission of the first pilot signal. The pilot addition means 111 does not transmit the first pilot signal during the transmission of the second pilot signal.
[0103] Thus, the conjugate component SC2* of the second subcarrier due to IQ mixing does not occur during the transmission of the first pilot signal of the first subcarrier SC1. Similarly, the conjugate component SC1* of the first subcarrier due to IQ mixing does not occur during the transmission of the second pilot signal of the second subcarrier SC2. As a result, under an environment in which interference or noise (conjugate component SC2* of the second subcarrier or conjugate component SC1* of the first subcarrier) does not occur, the MIMO equalizer can derive an optimal filter coefficient, and thus the reception characteristics are not degraded.
Furthermore, although not illustrated in FIG. 5, the written description also appears to teaches the use of a “data signal generation means” to perform some of the functionality of claim 1 (e.g., see [0097], which is reproduced above).
The claim, however, does not include the “pilot addition means”, the “optical modulation means”, or the “data signal generation means”. Furthermore, the Examiner notes that the claim has been amended to delete the “pilot addition means” and the “optical modulation means” (see the Nov. 20, 2023 amendment). As a result, the prosecution history makes it clear that the amended claim has a scope that requires neither the “pilot addition means” nor the “optical modulation means”.
In summary, the claim does not require the structure of the pilot addition means 111 or the optical modulation means (because they were removed from the claim in the amendment), and the claim does not require the data signal generation means (because it was never in the claim). The Examiner can find no support in the application to teach performing the functionality recited in the claim using only a memory and processor, and the Examiner can find no support in the prior art to teach that one of ordinary skill would know how to perform the recited functionality using only a processor and memory. Therefore, the claim has a scope that is broader than the teachings of the application.
Claim 11 recites an optical transmission apparatus that is similar to claim 1 but with the addition of functionality related to the generation of additional pilot signals related to X- polarization and Y-polarization optical signals, and the optical modulation of X- and Y-polarization optical signals, and additional functionality related to synthesizing the X and Y optical modulation signals. Like claim 1, claim 11 has been amended to remove the pilot addition means and optical modulation means. Claim 11 has also been amended to remove the “polarization synthesis means”. Like claim 1, claim 11 has a scope that requires no more than a memory and processor to perform the recited functionality.
FIG. 6 illustrates the optical transmission apparatus that teaches an optical transmission apparatus 11 that performs the functionality recited in the claim.
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This teaches generating the additional pilot signals, and the optical modulation of the X- and Y- polarization signals, and the polarization synthesis. Claim 11 does not recite the structure of this teaching, and the application does not appear to teach an embodiment using only a memory and processor to perform the recited functionality, and the Examiner can find no support in the prior art to teach that one of ordinary skill would know how to perform the claimed functionality using only a processor and memory as recited in the claim.
Claim 13 recites a system with a transmission apparatus similar to claim 1 plus an “other” transmission apparatus operating as an optical receiver. Like claim 1, claim 13 has been amended to remove various “means” elements and leaving the application to require only memory and processors to perform the recited functionality. FIG. 8 illustrates a basic diagram of the optical transmission apparatus 11 and the “another” optical transmission apparatus 12.
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The frequency characteristic difference compensation means 128 is illustrated in FIG. 9.
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Claim 13 does not recite the structure of this teaching, and the application does not appear to teach an embodiment using only a memory and processor to perform the recited functionality.
The Examiner notes that claim 13, line 18, recites “the pilot addition means”. However, this lacks antecedent basis because of the amendments to line 9 which removes the introduction of the “pilot addition means”. Furthermore, other instances of “pilot addition means” have been deleted in the amendment (see line 9 and 20). As a result, this “pilot addition means” in line 18 appears to be a typographical error.
In summary, the application teaches the recited functionality in the context of various “means” (and the application teaches structure for some of these “means”), but the claims do not recite the corresponding structures taught to perform the claimed functionality. This results in at least the independent claims having a broad scope that requires only memory and a processor. The application does not appear to teach how to make and used the claimed invention with only a memory and processor, and the Examiner can find no teaching or guidance in the application to support such a broad scope.
The dependent claims are rejected because the depend from the independent claims, and because the dependent claims recite additional functionality that appears to depend on the labeled boxes in the application.
When considering the teachings of the application and the scope of the claims, see MPEP 2173.05(g), 4th paragraph:
… Further, without reciting the particular structure, materials or steps that accomplish the function or achieve the result, all means or methods of resolving the problem may be encompassed by the claim. Ariad Pharmaceuticals., Inc. v. Eli Lilly & Co., 598 F.3d 1336, 1353, 94 USPQ2d 1161, 1173 (Fed. Cir. 2010) (en banc). Unlimited functional claim limitations that extend to all means or methods of resolving a problem may not be adequately supported by the written description or may not be commensurate in scope with the enabling disclosure, both of which are required by 35 U.S.C. 112(a) and pre-AIA 35 U.S.C. 112, first paragraph. In re Hyatt, 708 F.2d 712, 714, 218 USPQ 195, 197 (Fed. Cir. 1983); Ariad, 598 F.3d at 1340, 94 USPQ2d at 1167. …
This supports a finding that the broad scope of the claims may not be commensurate with the teachings in the disclosure.
No Teaching of a General Case for the Full Scope of the Claims.
The Examiner also notes that there is no teaching of an apparatus with the broad scope recited in the claims. For example, there is no teaching of a general case that can perform all of the recited functionality using only a memory and processor, and without requiring any more than what is recited in the claim (e.g., without requiring the various “means” elements discussed above and taught in the application for performing the recited functionality).
If such a general case were contemplated or discovered by the inventors, its disclosure and a description of its structure and operation would be expected as part of the application in order to support broad claims. This is particularly true because, as discussed above, the embodiments that are disclosed in the application are much more narrow than the claims and require particular elements that are not recited in the claims. These elements would be unnecessary if a general case had been known by the inventors, and yet the application does not include a disclosure of a general case that does not include these elements. This supports a conclusion that the scope of the claims is not commensurate with the teachings of the application.
Other Considerations.
The nature of the invention is optical transmission and reception apparatuses and methods. Some of the components used in the various embodiments were known to one of ordinary skill, such as memory and processors.
Furthermore, one of ordinary skill would know how to perform other tasks in the present technological area and related to the invention, such as providing power to components (although power supplies and power specifications are not explicitly taught in the application), and splicing and coupling the electrical and optical components together in a way that limits losses to a commercially acceptable level (although this is not explicitly taught in the application), and managing the temperature of electrical and optical components which are susceptible to performance degradation and undesirable operational variations based on temperature (although this is not explicitly taught in the application), and shielding components from EM interference because commercial systems routinely operate in the RF spectrum and would generate interference to electrical components within the system and outside of the system (although this is not explicitly taught). However, this knowledge and these modifications do not address the issues raised above regarding the scope of the claims and the teachings of the application.
The application does teach particular elements arranged in particular combinations in order to achieve the desired results (e.g., see FIGS. 5, 6, 8, and 9, which are reproduced above). However, there does not appear to be any teaching or guidance in the prior art or in the application that would allow one of ordinary skill to make the full scope of the claim (e.g., using only memory and a processor).
Broadest Reasonable Interpretation and Opportunity to Amend.
During prosecution, Applicant has an opportunity to amend the claims to the desired scope. See MPEP 2111, 4th paragraph:
Because applicant has the opportunity to amend the claims during prosecution, giving a claim its broadest reasonable interpretation will reduce the possibility that the claim, once issued, will be interpreted more broadly than is justified. In re Yamamoto, 740 F.2d 1569, 1571 (Fed. Cir. 1984); In re Zletz, 893 F.2d 319, 321, 13 USPQ2d 1320, 1322 (Fed. Cir. 1989) (“During patent examination the pending claims must be interpreted as broadly as their terms reasonably allow.”); In re Prater, 415 F.2d 1393, 1404-05, 162 USPQ 541, 550-51 (CCPA 1969) … See also In re Morris, 127 F.3d 1048, 1054-55, 44 USPQ2d 1023, 1027-28 (Fed. Cir. 1997) (The court held that the PTO is not required, in the course of prosecution, to interpret claims in applications in the same manner as a court would interpret claims in an infringement suit. Rather, the “PTO applies to verbiage of the proposed claims the broadest reasonable meaning of the words in their ordinary usage as they would be understood by one of ordinary skill in the art, taking into account whatever enlightenment by way of definitions or otherwise that may be afforded by the written description contained in applicant’s specification.”).
Therefore, if Applicant intends the claims to have a scope that is narrower than the broadest reasonable interpretation (e.g., if Applicant intends the claims to include additional elements not recited in the claims), the claims should be amended during prosecution to more clearly provide the intended scope.
Conclusion.
After careful consideration of the factors, the Examiner has concluded that the claims are not commensurate with the teachings in the application, and undue experimentation would be required to make and use the full scope of the claims.
Multiple 112(a) Rejections and Compact Prosecution.
In the interests of compact prosecution it was assumed, for the purposes of the Scope of Enablement rejection, that the specification enables the invention for at least some scope. However, it is not clear to the Examiner that this is the case. As a result, the claims are also rejected below for failing to comply with 35 USC 112(a) Enablement and 35 USC 112(a) Written Description. The multiple 112(a) rejections are presented in the interests of compact prosecution.
Claim Rejections - 35 USC § 112 - Enablement
The following is a quotation of the first paragraph of 35 U.S.C. 112(a):
(a) IN GENERAL.—The specification shall contain a written description of the invention, and of the manner and process of making and using it, in such full, clear, concise, and exact terms as to enable any person skilled in the art to which it pertains, or with which it is most nearly connected, to make and use the same, and shall set forth the best mode contemplated by the inventor or joint inventor of carrying out the invention.
The following is a quotation of the first paragraph of pre-AIA 35 U.S.C. 112:
The specification shall contain a written description of the invention, and of the manner and process of making and using it, in such full, clear, concise, and exact terms as to enable any person skilled in the art to which it pertains, or with which it is most nearly connected, to make and use the same, and shall set forth the best mode contemplated by the inventor of carrying out his invention.
Claims 1-11 and 13-21 are rejected under 35 U.S.C. 112(a) or 35 U.S.C. 112 (pre-AIA ), first paragraph, as failing to comply with the enablement requirement. The claim(s) contains subject matter which was not described in the specification in such a way as to enable one skilled in the art to which it pertains, or with which it is most nearly connected, to make and/or use the invention.
Claim 1 recites functionality associated with the teachings in the application for the pilot addition means, the optical modulation means, and the data signal generation means (see the discussion in the Scope of Enablement rejection). However, the application does not appear to teach how to make and use these “means” elements. The pilot addition means and the optical modulation means are illustrated in FIG. 5 as labeled boxes without illustrating their structure or teaching how they would be made. The data signal generation means does not appear to be illustrated in the figures, and does not appear to be described in the written description. In other words, application does not teach how to make the structure that performs the functionality recited in the claim.
Claim 1 has also been amended to recite a memory and a processor to perform a variety of functions. The application does not appear to teach how to use a memory and processor to perform the functionality recited in the claims. The application also does not appear to use the term “processor” outside of the amended claims.
Claim 11 recites functionality associated with the pilot addition means, the optical modulation means, the data signal generation means, and the polarization synthesis means. However, the pilot addition means, the optical modulation means, and the polarization synthesis means are illustrated as labeled boxes and the application does not appear to teach how those elements would be made (e.g., see FIG. 6). FIG. 6 does not illustrate the data signal generation means. See the discussion in the Scope of Enablement rejection. In other words, application does not teach how to make the structure that performs the functionality recited in the claim.
Claim 11 has also been amended to recite a memory and a “processor” to perform a variety of functions. The application does not appear to teach how to use a memory and processor to perform the functionality recited in the claims. The application also does not appear to use the term “processor” outside of the amended claims.
Claim 13 recites functionality associated with the teachings in the application for at least the pilot addition means, the optical modulation means, the data signal generation means, the optical signal reception means, and the position detection means. However, the application illustrates most of these elements as labeled boxes and without a teaching of how they would be made (e.g., see FIG. 8). See the discussion in the Scope of Enablement rejection. In other words, application does not teach how to make the structure that performs the functionality recited in the claim.
Claim 13 has also been amended to recite a memory and a “processor” to perform a variety of functions. The application does not appear to teach how to use a memory and processor to perform the functionality recited in the claims. The application also does not appear to use the term “processor” outside of the amended claims.
The dependent claims are rejected because the depend from the independent claims, and because many of the dependent claims recite additional functionality that appears to depend on the labeled boxes in the application.
As a result, it appears that the claims recite functionality related to claimed structures that are not described in the specification in such a way as to enable one skilled in the art to which it pertains, or with which it is most nearly connected, to make and/or use the invention.
Claim Rejections - 35 USC § 112 - Written Description
The following is a quotation of the first paragraph of 35 U.S.C. 112(a):
(a) IN GENERAL.—The specification shall contain a written description of the invention, and of the manner and process of making and using it, in such full, clear, concise, and exact terms as to enable any person skilled in the art to which it pertains, or with which it is most nearly connected, to make and use the same, and shall set forth the best mode contemplated by the inventor or joint inventor of carrying out the invention.
The following is a quotation of the first paragraph of pre-AIA 35 U.S.C. 112:
The specification shall contain a written description of the invention, and of the manner and process of making and using it, in such full, clear, concise, and exact terms as to enable any person skilled in the art to which it pertains, or with which it is most nearly connected, to make and use the same, and shall set forth the best mode contemplated by the inventor of carrying out his invention.
Claims 1-11 and 13-21 are rejected under 35 U.S.C. 112(a) or 35 U.S.C. 112 (pre-AIA ), first paragraph, as failing to comply with the written description requirement. The claim(s) contains subject matter which was not described in the specification in such a way as to reasonably convey to one skilled in the relevant art that the inventor or a joint inventor, or for applications subject to pre-AIA 35 U.S.C. 112, the inventor(s), at the time the application was filed, had possession of the claimed invention.
As discussed in the Enablement and the Scope of Enablement rejections, the claims recite functionality associated with elements in the application that are not described in the specification in such a way as to reasonably convey to one skilled in the relevant art that the inventor or a joint inventor, at the time the application was filed, had possession of the claimed invention.
Claim Rejections - 35 USC § 112 - Indefinite
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 1-11 and 13-21 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.
Claim 1, line 3 has been amended to recite a “processor”. The written description, however, does not appear to use the term “processor” outside of the amended claims, and does not appear to teach how to use a “processor” to perform the functionality of the invention. Therefore, it is not clear how to interpret this element or what particular structure is within its scope. For the purposes of this Action, the term “processor” will be interpreted as a conventional signal processor (e.g., see the PG Pub at [0232]).
Claims 2-10 are rejected because they depend from claim 1 and fail to further limit the scope in such a manner as to overcome the rejections.
Claim 11, line 20 recites “synthesize”. It is not clear how to interpret this term in the context of the claimed invention. The written description appears to define this term to “sometimes” mean “multiplexing”. See, for example:
[0198] A system 50 according to a fifth example embodiment uses an equalizer to detect and compensate for frequency characteristic differences in a state where a plurality of subcarrier SCs are independent. For example, when an equalizer is provided in reception means of an optical transmission apparatus, the equalizer is provided after the separation of the plurality of subcarrier SCs. As another example, when the equalizer is provided in transmission means of an optical transmission apparatus, the equalizer is provided before the synthesis of the plurality of subcarrier SCs. The synthesis is sometimes referred to as multiplexing.
However, the full scope of the term is not clear. In other words, it is not clear if “synthesize” in the claim should be interpreted as “multiplex” (in which case the Examiner suggests amending the claim to replace “synthesize” with “multiplex”) or if “synthesize” is intended to be interpreted more broadly (in which case the full scope of that term is not clear).
Claim 11, line 4 has also been amended to recite a “processor”. See the discussion of claim 1.
Claim 13 , lines 3-4 recites an “another one of the optical transmission apparatus configured to receive an optical modulation signal ...”. It is not clear how to interpret an optical transmitter configured or otherwise recited to perform as an optical receiver. See also lines 23 to the end of the claim in which the “other” optical transmission apparatus is described in terms of functionality of an optical receiver. It may be that these are typographical errors and the “transmission” apparatuses should be “receiving” apparatuses (in which case the Examiner suggests amending the claim to make this clear) or if there is some typographical error in the functionality recited in the claim (in which case the Examiner suggests amending the claim to make the functionality clear). In any event, amendment and clarification is required.
Claim 13, line 8, has also been amended to recite a “processor”. See the discussion of claim 1.
Claim 13, line 18 recites “the pilot addition means”. There is insufficient antecedent basis for this term. The Examiner notes that the introduction of the “pilot addition means” was deleted in line 9, and it may be that “the pilot addition means” should have been deleted.
Claim 13, line 23 recites “the other optical transmission apparatus”. There is insufficient antecedent basis for this limitation. The Examiner notes that lines 3-4 introduces “another one of the optical transmission apparatus”. It is not clear if the “other” optical transmission apparatus in line 23 is meant to be the “another one of the” optical transmission apparatus from line 3 (in which case the Examiner suggests using consistent terminology) or of they are different (in which case there is a lack of antecedent basis in line 23). In any event, amendment is required.
Claims 14-21 are rejected because they depend from claim 13 and fail to further limit the scope in a manner to overcome the rejection of claim 13.
Conclusion
The prior art made of record and not relied upon is considered pertinent to applicant's disclosure.
JP 2020-141294 (Nippon; submitted by Applicant) at FIG. 1 illustrates a system including a training signal insertion unit 113 and an IQ modulator 141).
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The copy of the reference submitted by Applicant presents an English translation for only the Abstract. The description of the art presented above is from the Written Opinion of the ISA for the corresponding PCT application (cited in PTO-892 and copy attached).
US 2008/0310534 (Egashira) at FIG. 5 illustrates an optical receiver with an IQ imbalance estimating unit 506 and IQ imbalance compensation unit 503.
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See also:
[0059] The OFDM receiver 103 in FIG. 1 will be described below with reference to FIG. 5. The OFDM receiver 103 includes a wireless reception unit 501 having a quadrature demodulator, an FFT (Fast Fourier Transform) unit 502, a reception IQ imbalance compensation unit 503, a transfer characteristic estimating unit 504, a transmission IQ imbalance removing unit 505, a reception IQ imbalance estimating unit 506, a channel estimating unit 507, a channel equalizing unit 508, and a decoder 509.
[0083] The reception IQ imbalance estimating unit 506 estimates a reception IQ imbalance characteristic from the transfer characteristic, and supplies a signal S506 indicating the reception IQ imbalance characteristic to the reception IQ imbalance compensation unit 503.
[0084] The reception IQ imbalance compensation unit 503 performs processing for compensating the influence of the reception IQ imbalance to the channel estimating preamble signal Z.sub.rx(k) and data signal D.sub.rx(k) fed from the FFT unit 502 according to the computed reception IQ imbalance characteristic. A channel estimating preamble signal S507 and a data signal S508, in which the influence of the reception IQ imbalance is compensated, are fed into the channel estimating unit 507 and the channel equalizing unit 508 respectively.
FIG. 11 illustrates another embodiment including a pilot signal generating unit 1101, a transmission signal generating unit 1102, a transmission IQ imbalance removing unit 1108, and a reception IQ imbalance estimating unit 1109.
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FIG. 12 illustrates the signal produced by the pilot signal generating unit 1101.
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In other words, FIG. 12 teaches to generate digital signals (e.g., the digital signals at different times in FIG. 12) by adding pilot signals at frequencies above and below the carrier frequency. As can also be seen in FIG. 12, the pilot signals are transmitted at different times, so one pilot signal is not transmitted with the other is transmitted, and vice versa. See also:
[0221] In an interval from a time t.sub.1 to a time t.sub.1+.DELTA., the pilot signal is transmitted at a frequency +f.sub.1. In an interval from a time t.sub.2 to a time t.sub.2+.DELTA., the pilot signal is transmitted at a frequency -f.sub.1. In an interval from a time t.sub.3 to a time t.sub.3+.DELTA., the pilot signal is transmitted at a frequency +f.sub.2. In an interval from a time t.sub.4 to a time t.sub.4+.DELTA., the pilot signal is transmitted at a frequency -f.sub.2. In an interval from a time t.sub.n to a time t.sub.n+.DELTA., a pilot signal transmitted at a frequency f is defined by p.sub.tx(f,t.sub.n). At this point, a relationship of n=2k-1 holds for the pilot signal transmitted with a positive frequency +f.sub.k (k=1, 2), and a relationship of n=2k holds for the pilot signal transmitted with a negative frequency -f.sub.k (k=1, 2).
[0222] The pilot signals are transmitted with a pair of frequencies symmetrically located in relation to the center frequency. That is, assuming that S.sub.f is a frequency pair with which the pilot signals are transmitted, -f.sub.k.epsilon.S.sub.f holds in the case of +f.sub.k.epsilon.S.sub.f.
[0223] In the fifth embodiment, the pilot signals are transmitted at different times in each frequency. However, the method of transmitting the pilot signals is not limited to the fifth embodiment. When the two pilot signals symmetrically located in relation to the center frequency are transmitted at different times, the pilot signals can arbitrarily be transmitted. For example, the two pilot signals p.sub.tx(+f.sub.1,t.sub.1) and p.sub.tx(+f.sub.2,t.sub.3) which are not in symmetrical relation to the center frequency may be transmitted at the same time t.sub.1=t.sub.3. The pilot signals may be transmitted in the order of t.sub.2=t.sub.3<t.sub.4<t.sub.1.
It also teaches that the pilot and data signals can be transmitted concurrently. See:
[0262] In the case where another wireless communication apparatus transmits the pilot signals, another wireless communication apparatus may concurrently transmit the data signals using the frequency, time, code system, and transmitting antenna which are different from those of the pilot signal.
See also FIGS. 7-9, and 14 which illustrate other embodiments.
US 2016/0112143 (Yu) at FIG. 2 illustrates an optical communication system including an optical transmitter 102 and optical receivers 106 that detects and compensates for I/Q imbalance.
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FIG. 4 illustrates details of the optical receivers, including a Digital Signal Processor and the signal processing functions performed by the DSP, including IQ Imbalance Compensation 408.
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See, for example:
[0033] FIG. 4 depicts an example of various signal processing tasks 400 performed digitally for receiver processing of the dual-subcarrier 16QAM OFDM signal. At the receiver, the Dual-subcarrier 16QAM-OFDM can be equalized with a CMMA method, such as the 49QAM-based CMMA, without any additional spectral overhead. After integrated receiver (402, for optical to electrical conversion and 404 for analog to digital conversion) corresponding to I and Q components of x- and y-polarized signals), for verifying performance results, four signal components I.sub.x, Q.sub.x, I.sub.y and Q.sub.y may be captured by a real-time oscilloscope with 80-GSa/s sample rate. The four signal components may be processed through a T/2-spaced time-domain finite impulse response (FIR) filter that is used for chromatic dispersion compensation (CDC) 406, where the filter coefficients are calculated from the known fiber CD transfer function using the frequency-domain truncation method. An IQ imbalance compensation module 408 may operate on the output of the Electrical CDC filter 406 to suppress or eliminate the imbalance between I and Q components of the received signals. A resampling module 410 may be used to resample the received signals based on the results of calculation of a clock recover module 412.
FIG. 9 illustrates a process performed in the receiver.
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[0042] FIG. 9 is a flowchart representation of an example process 900 of optical communication. The process 900 can be implemented in an optical signal receiver electronics, e.g., in apparatus 102, 106.
[0043] At 902, the process 900 includes receiving the two-subcarrier, or dual subcarrier, OFDM signal. The signal may be received via a glass or plastic optical fiber transmission medium. In some embodiments, the received two-subcarrier OFDM signal may include two PDM components, each of which comprises a two-subcarrier OFDM signal component.
[0044] At 904, the process 900 includes converting the two-subcarrier OFDM signal into a time domain Quadrature Amplitude Modulation (QAM) signal. The conversion may include transforming the two-subcarrier OFDM using an inverse Fourier transform (e.g., module 418).
[0045] At 906, the process 900 includes performing blind equalization of the time domain QAM signal to recover the data. In some embodiments, the blind equalization may be performed using a cascaded multi-modulus algorithm (CMMA) which includes performing channel equalization of the received two-subcarrier OFDM signal to obtain a set of channel estimation coefficients and a stream of symbols, partitioning, based on a modulus of the stream of symbols, the stream of symbols into multiple partitions, estimating a carrier frequency offset based on the partitioned stream of symbols, and recovering a phase of the received two-subcarrier OFDM signal using a maximum likelihood algorithm. In addition, the CMMA may further include rotating at least some constellation points. The rotating operation may be performed during the operation of estimating the carrier frequency offset or during recovering the phase of the signal.
US 2010/0303474 (NAKASHIMA) at FIG. 5 illustrates an I/Q amplitude imbalance compensation circuit 30 and an I/Q phase error compensation circuit 40.
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[0043] FIG. 5 illustrates a configuration of the digital coherent optical receiver in the second embodiment. The digital coherent optical receiver in the second embodiment includes an I-Q amplitude error compensation circuit 30 and an I-Q phase error compensation circuit 40. In the second embodiment, the I-Q phase error compensation circuit 40 compensates for an I-Q phase error by a feed-forward method. It is assumed that the real part signal I.sub.1 and the imaginary part signal Q.sub.1 illustrated in the above expression (1) are input to the digital coherent optical receiver for each symbol. Each of I.sub.1 and Q.sub.1 are a predetermined number of bits of digital data.
[0044] The I-Q amplitude error compensation circuit 30 includes a squaring circuit 31a, an averaging circuit 32a, a differential circuit 33a, a multiplier 34a, an accumulation adder 35a, and a multiplier 36a in order to correct the real part signal I.sub.1. In the following description, a signal output from the multiplier 36a is called I.sub.2.
[0051] The signals I.sub.2 and Q.sub.2 obtained by the I-Q amplitude error compensation circuit 30 are given to the I-Q phase error compensation circuit 40. At this time, the I-Q amplitude error of the signals I.sub.2 and Q.sub.2 has been compensated for and both of the amplitude of the signals I.sub.2 and Q.sub.2 has been normalized. The signal process by the I-Q amplitude error compensation circuit 30 is expressed by expression (2).
US 2012/0057863 (Winzer) at FIG. 1A illustrates an optical receiver including a DSP 150.
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FIG. 4 illustrates a processing module used in the DSP that implements I/Q signal imbalance correction.
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[0054] Processing module 400 implements both frequency-resolved I/Q-signal imbalance correction and electronic dispersion compensation in the frequency domain so that both of these operations can share the functionality of DFT sub-modules 312.sub.1 and 312.sub.2, complex-IDFT sub-module 322, and OLA filter 326. A multiplication sub-module 416 coupled between CN generator 318 and complex-IDFT sub-module 322 performs electronic dispersion compensation by generating a product of complex-valued spectrum E(.DELTA.f) produced by CN generator 318 and a dispersion-correction function, H.sub.D. Function H.sub.D spectrally filters spectrum E(.DELTA.f) so as to reduce the detrimental effects of phase and amplitude distortions imposed by chromatic dispersion in the optical transmission link. The output of multiplication sub-module 416 is an EDC-corrected complex-valued spectrum, E Ulf), which is thereafter processed similar to complex-valued spectrum E(.DELTA.f) in FR-IQIC module 310 (FIG. 3B). Representative methods that can be used to determine function H.sub.D for use in processing module 400 are disclosed, e.g., in U.S. Pat. No. 7,623,578, which is incorporated herein by reference in its entirety.
It also teaches some variations of the invention, including implementing I/Q imbalance correction in the transmitter:
[0064] While this invention has been described with reference to illustrative embodiments, this description is not intended to be construed in a limiting sense. For example, although various embodiments of the invention have been described in reference to optical receivers, the principle of the invention can similarly be applied to optical transmitters. More specifically, frequency-dependent I/Q-signal imbalance correction can be applied to correct any imbalances that might be present in the "front end" of an optical transmitter, wherein such front end comprises optoelectronic circuitry for converting electrical digital signals into modulated optical signals. The front end typically has one or more I/Q channels, each of said I/Q channels being adapted to convert a respective digital I/Q-signal pair into a corresponding component of a modulated optical signal. A digital signal processor is used to process the one or more digital I/Q-signal pairs before these signals are applied to the front end so as to impose a frequency-dependent I/Q-signal imbalance correction that pre-compensates for the frequency-dependent I/Q-signal imbalance produced by the front end. As a result, the transmitter is able to mitigate the detrimental effects of the front-end's frequency-dependent I/Q-signal imbalance on the modulated optical signal.
US 2012/0189320 (Zelensky) at FIG. 1 illustrates an optical communication system.
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FIG. 6 illustrates an I/Q compensator.
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[0044] In other embodiments, a small amount of positive or negative skew is added to I and Q samples, and correlation between first derivatives of samples of the samples are evaluated to determine if the positive or negative skew decreased correlation. One exemplary embodiment of such a system is illustrated in the block diagram of FIG. 6. The skew compensation system 600 in FIG. 6 includes a DC offset compensation module 605 that receives I and Q input channels. A DC compensated version of the I and Q channels are provided to skew compensation module 610. The skew compensation module 610 adjusts the I and/or Q channels to compensate for any detected skew, and provides the compensated output to phase and amplitude compensation module 615. The phase and amplitude compensation module 615 compensates for phase and amplitude imbalance, and provides the compensated I and Q channels to the next component of the demodulator. In this embodiment, a correlation module 620 is connected to each of the I and Q outputs and determines a correlation between derivatives of samples of the I and Q channels. The correlation module 620 of some embodiments determines a magnitude of the product of the first derivatives of the I and Q samples and passes the results through an infinite impulse response (IIR) low-pass filter. The correlation module 620 provides correlation information to skew update module 625.
See also [0045]-[0047] which further discusses FIG. 6. See also FIGS. 7-9 which illustrate other embodiments.
Any inquiry concerning this communication or earlier communications from the examiner should be directed to DARREN WOLF whose telephone number is (571)270-3378. The examiner can normally be reached Monday through Friday, 7:00 AM to 3:00 PM.
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/DARREN E WOLF/Primary Examiner, Art Unit 2634