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 .
Claim Rejections - 35 USC § 102
The following is a quotation of the appropriate paragraphs of 35 U.S.C. 102 that form the basis for the rejections under this section made in this Office action:
A person shall be entitled to a patent unless –
(a)(1) the claimed invention was patented, described in a printed publication, or in public use, on sale, or otherwise available to the public before the effective filing date of the claimed invention.
(a)(2) the claimed invention was described in a patent issued under section 151, or in an application for patent published or deemed published under section 122(b), in which the patent or application, as the case may be, names another inventor and was effectively filed before the effective filing date of the claimed invention.
Claims 16, 25, 28, and 35 are rejected under 35 U.S.C. 102(a)(1) as being anticipated by Cummings et al. (I. T. Cummings, J. P. Doane, T. J. Schulz and T. C. Havens, "Aperture-Level Simultaneous Transmit and Receive With Digital Phased Arrays," in IEEE Transactions on Signal Processing, vol. 68, pp. 1243-1258, 2020, doi: 10.1109/TSP.2020.2968262.).
Regarding claim 16, Cummings teaches,
A method (abs., “This optimization procedure balances the goal of null-placement for interference and noise rejection with the goal of maintaining high transmit and receive gain”) comprising:
at a radar system including a first transmitter channel and a first receive channel (fig. 4, noting that “While it is natural to discuss STAR from a communications point of view, the techniques detailed in this paper enable applications in communications, radar, imaging, and multi-function systems.”),
in a first mode of operation determining a first channel response between the first transmitter channel and the first receive channel (“Ho ∈ CJ×J is a diagonal matrix which represents the fixed attenuator between each transmit channel and its corresponding observation receive channel as shown in Fig. 4. Like M, Ho must be estimated in practice by a channel sounding technique.”); and
in a second mode of operation of the radar system, precoding a sense signal to be transmitted based on the first channel response (“The adaptive transmit beamformer creates nulls to reduce the incident transmitted signal and noise on the receivers in order to avoid receiver saturation, thereby lowering the noise floors of the limited dynamic range receive channels, while still achieving high transmit gain in the direction of interest.” See also, “Their signal-to-leakage-plus-noise-ratio (SLNR) based precoding technique is similar to the one proposed in this work. However, our objective function also accounts for the noise injected into the receive channel by the digital SIC process and the limited dynamic range of the transmit and receive channels.”).
Regarding claim 25, Cummings teaches,
A method (abs., “This optimization procedure balances the goal of null-placement for interference and noise rejection with the goal of maintaining high transmit and receive gain”), comprising:
in a calibration mode of operation of a radar system (fig. 4, noting that “While it is natural to discuss STAR from a communications point of view, the techniques detailed in this paper enable applications in communications, radar, imaging, and multi-function systems.”), determining characteristics of a self-interference signal between a transmitter channel and a receive channel of the radar system (“Ho ∈ CJ×J is a diagonal matrix which represents the fixed attenuator between each transmit channel and its corresponding observation receive channel as shown in Fig. 4. Like M, Ho must be estimated in practice by a channel sounding technique.”); and
in a sensing mode of operation of the radar system, precoding a signal to be transmitted based on the determined characteristics of the self-interference signal (“The adaptive transmit beamformer creates nulls to reduce the incident transmitted signal and noise on the receivers in order to avoid receiver saturation, thereby lowering the noise floors of the limited dynamic range receive channels, while still achieving high transmit gain in the direction of interest.”).
Claim 28 is rejected for the same reasons and using the same citations as claim 1. The examiner notes that Cummings further teaches,
A radar system (fig. 2) comprising: a first transmitter channel and a first receive channel (fig. 2); and a processor (abs., “This approach, referred to as Aperture-Level Simultaneous Transmit and Receive (ALSTAR), uses only adaptive digital beamforming and digital SIC techniques.” See also Acknowledgements, “Portage, a high-performance computing infrastructure at Michigan Technological University, was used in obtaining results presented in this publication.”)…
Regarding claim 35, Cummings teaches,
The radar system of claim 28, wherein the radar system comprises a plurality of transmitter channels including the first transmitter channel and a plurality of receivers including the first receiver (fig. 2), and wherein the radar system is configured to precode signals to be transmitted for each of the plurality of transmitter channels of the radar system (fig. 2, noting that the transmit beamformer bt- is where the precoding occurs and is shown existing for each transmit element).
Claim Rejections - 35 USC § 103
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.
The factual inquiries for establishing a background for determining obviousness under 35 U.S.C. 103 are summarized as follows:
1. Determining the scope and contents of the prior art.
2. Ascertaining the differences between the prior art and the claims at issue.
3. Resolving the level of ordinary skill in the pertinent art.
4. Considering objective evidence present in the application indicating obviousness or nonobviousness.
Claims 17-18, 21-24, 26-27, 29, and 32-34 are rejected under 35 U.S.C. 103 as being unpatentable over Cummings in view of Wikipedia (Wikipedia. "Channel State Information" (22 September 2021). Accessed via Wayback Machine).
Regarding claim 17, Cummings teaches the method of claim 16. Cummings further teaches that the first channel response should be estimated using a channel sounding technique (“Ho ∈ CJ×J is a diagonal matrix which represents the fixed attenuator between each transmit channel and its corresponding observation receive channel as shown in Fig. 4. Like M, Ho must be estimated in practice by a channel sounding technique.”), but does not explicitly teach,
…wherein determining the first channel response comprises: transmitting a calibration signal; and determining the first channel response based on a signal in response to transmitting the calibration signal.
Wikipedia teaches,
…wherein determining the first channel response comprises: transmitting a calibration signal; and determining the first channel response based on a signal in response to transmitting the calibration signal. (“Since the channel conditions vary, instantaneous CSI needs to be estimated on a short-term basis. A popular approach is so-called training sequence (or pilot sequence), where a known signal is transmitted and the channel matrix H is estimated using the combined knowledge of the transmitted and received signal.”).
Wikipedia is analogous to the claimed invention because it is in the same field of endeavor. It would have been obvious to someone of ordinary skill in the art before the effective filing date of the claimed invention to use the channel sounding technique of Wikipedia to determine the channel matrix H of Cummings because the channel sounding technique of Wikipedia is a common approach to channel sounding and would have the obvious result of accomplishing the channel sounding needed for the precoding of Cummings.
Regarding claim 18, Cummings in view of Wikipedia teaches the method of claim 17. Cummings further teaches,
…further comprising: transmitting the precoded sense signal in the second mode (“The adaptive transmit beamformer creates nulls to reduce the incident transmitted signal and noise on the receivers in order to avoid receiver saturation, thereby lowering the noise floors of the limited dynamic range receive channels, while still achieving high transmit gain in the direction of interest.” See also fig. 6, “For Pt=2500 W at broadside with adaptive transmit and receive beamformers, a maximum EII of 187.1 dB is found, an improvement of 108.6 dB over a non-adaptive array without SIC, and an isolation improvement of 40 dB over that realizable by SIC alone.”).
Regarding claim 21, Cummings in view of Wikipedia teaches the method of claim 17. Cummings further teaches,
…wherein precoding the sense signal comprises: generating a precoding matrix based on the first channel response; and precoding the first received signal based on the precoding matrix (“Specifically, optimization of the receive beamformer can dramatically reduce the contribution of the observation noise, which is represented by the first line of (19). This receive beamforming optimization problem is diagonally loaded by the elevated receive noise floor due to high-power self-interference and limited receiver dynamic range, which is represented in the second and third lines of (19), and by the receiver thermal noise power, given in the last line of (19)… In turn, optimization of the transmit beamformer provides a method to mitigate receiver noise by reducing the incident power at each receive channel, thus improving receiver sensitivity and preventing saturation. This is represented in the second line of (21). The transmit beamforming optimization problem is likewise diagonally loaded by the observation noise and the elevated receiver noise floor due to the coupled transmitter noise, represented in the first and third lines of (21), and by the receiver thermal noise power, given in the last line of (21). Optimizing the transmit and receive beamformers to minimize noise while forming the desired beam in the far field is discussed in the next section.”).
Regarding claim 22, Cummings in view of Wikipedia and further in view of Cope teaches the method of claim 21. Cummings further teaches that generating a precoding matrix can comprise generating a zero-forcing precoding matrix (“Several authors have written about methods for beamforming in FD MIMO networks referred to as zero-forcing, null-space-projection, or interference alignment [108]–[114]. Interference alignment extends the concept of zero-forcing beamforming to include null-space constraints on inter-user interference.”). Cummings further teaches that its interference alignment system can be designed to null out a particular Tx-Rx path (“For example, in the case of a linear ALSTAR array that has a contiguous transmit subarray and a contiguous receive subarray, a single end-fire null aimed at the other subarray in the transmit and receive beam would be all that is required to minimize the noise.”).
Although Cummings does not explicitly teach that said null is formed via zero-forcing beamforming, it would be obvious to a person of ordinary skill in the art to combine the teachings of the introduction of Cummings that null-space-projection can be done via zero-forcing beamforming with the note that the invention of Cummings includes an end-fire null aimed at the other subarray to suggest that said end-fire null can be accomplished through zero-forcing beamforming.
Regarding claim 23, Cummings in view of Wikipedia teaches the method of claim 21. Cummings further teaches,
wherein generating the precoding matrix comprises generating a limiting precoding matrix (“Likewise, the transmit beamformer needs only to suppress the limited dynamic range receive noise beneath the observation noise and receive channel thermal noise. This can be seen in (19) and (21), where the non-diagonal component represents the noise to be nulled and the diagonal components act as regularization terms that reduce the distortion in the desired main transmit and receive beams. Finally, antennas are often laid out in very regular patterns in phased arrays, which implies strong similarities between the coupling channels across antennas. This often leads to a coupling matrix with a few dominant modes and a high condition number, reducing the number of DOF required to achieve strong mutual nulls. For example, in the case of a linear ALSTAR array that has a contiguous transmit subarray and a contiguous receive subarray, a single end-fire null aimed at the other subarray in the transmit and receive beam would be all that is required to minimize the noise…Yet, in strong multipath environments, the effective rank of M will be increased, more DOF will be required for nulls in the transmit and receive beams, resulting in reduced transmit gain, receive gain, and EII.”).
Regarding claim 24, Cummings in view of Cope and further in view of Wikipedia teaches the method of claim 23. Cummings further teaches (note: what Cummings does not teach is struck through),
…wherein the limiting precoding matrix is generated to limit the level of one or more received signals(“Second, perfect nulls are unnecessary in this scenario [74]. The receive beamformer needs only to suppress the observation noise beneath the receive channel noise due to limited dynamic range and receive channel thermal noise. Likewise, the transmit beamformer needs only to suppress the limited dynamic range receive noise beneath the observation noise and receive channel thermal noise.” See also abs., “Results are also presented for a regularized version of the beamformer optimization problem that allows the designer to trade EII for array gain.”).
Although Cummings does not explicitly teach an analog-to-digital converter for the radar system, the fact that both transmit and receive beamforming is done digitally suggests that an ADC is necessary to convert analog antenna signals into digital signals for digital beamforming. Thus, it would be obvious to a person of ordinary skill in the art at time of filing to include ADCs in the receiver chain.
Regarding claim 26, Cummings teaches the method of claim 25. Cummings further teaches that channel estimation is a necessary step in determining the precoding matrix (“Ho ∈ CJ×J is a diagonal matrix which represents the fixed attenuator between each transmit channel and its corresponding observation receive channel as shown in Fig. 4. Like M, Ho must be estimated in practice by a channel sounding technique.”). However, Cummings does not explicitly teach,
…wherein determining characteristics of the self-interference signal comprises: transmitting a calibration signal in the calibration mode of operation; and determining the characteristics of the self-interference signal based on a received signal received in response to the calibration signal.
Wikipedia teaches,
…wherein determining characteristics of the self-interference signal comprises: transmitting a calibration signal in the calibration mode of operation; and determining the characteristics of the self-interference signal based on a received signal received in response to the calibration signal (“Since the channel conditions vary, instantaneous CSI needs to be estimated on a short-term basis. A popular approach is so-called training sequence (or pilot sequence), where a known signal is transmitted and the channel matrix H is estimated using the combined knowledge of the transmitted and received signal.”).
Wikipedia is analogous to the claimed invention because it is in the same field of endeavor. It would have been obvious to someone of ordinary skill in the art before the effective filing date of the claimed invention to use the channel sounding technique of Wikipedia to determine the channel matrix H of Cummings because the channel sounding technique of Wikipedia is a common approach to channel sounding and would have the obvious result of accomplishing the channel sounding needed for the precoding of Cummings.
Regarding claim 27, Cummings in view of Wikipedia teaches the method of claim 26. Cummings further teaches,
…wherein determining characteristics of the self-interference signal comprises: determining a precoding matrix based on the received signal (“Specifically, optimization of the receive beamformer can dramatically reduce the contribution of the observation noise, which is represented by the first line of (19). This receive beamforming optimization problem is diagonally loaded by the elevated receive noise floor due to high-power self-interference and limited receiver dynamic range, which is represented in the second and third lines of (19), and by the receiver thermal noise power, given in the last line of (19)… In turn, optimization of the transmit beamformer provides a method to mitigate receiver noise by reducing the incident power at each receive channel, thus improving receiver sensitivity and preventing saturation. This is represented in the second line of (21). The transmit beamforming optimization problem is likewise diagonally loaded by the observation noise and the elevated receiver noise floor due to the coupled transmitter noise, represented in the first and third lines of (21), and by the receiver thermal noise power, given in the last line of (21). Optimizing the transmit and receive beamformers to minimize noise while forming the desired beam in the far field is discussed in the next section.”).
The examiner notes that Cummings does not teach the specific channel sounding technique used, but does teach that channel sounding results in received matrices M, H that are used in the above precoding techniques.
Claim 29 is rejected for the same reasons and using the same citations as claim 17, above.
Claim 32 is rejected for the same reasons and using the same citations as claim 21, above.
Claim 33 is rejected for the same reasons and using the same citations as claim 22, above.
Claim 34 is rejected for the same reasons and using the same citations as claim 23, above.
Claims 19-20 and 30-31 are rejected under 35 U.S.C. 103 as being unpatentable over Cummings in view of Wikipedia and further in view of Cope et al. (U.S. Pat. No. 5689267 A), hereinafter Cope.
Regarding claim 19, Cummings in view of Wikipedia teaches the method of claim 18. Cummings in view of Wikipedia does not teach,
…wherein the precoded sense signal is a higher power signal than the calibration signal.
Cope teaches that a calibration signal should be a lower power than a typical sensing signal (col. 3, lines 45-54, “In the test mode, the program transmits a test output signal instead of the nominal output signal. The preferred test output signal presents a reduced energy level as a pulse having a time pulse width of 1 microsecond instead of the nominal 4 microseconds. As a result, the test output signal energy is about one fourth that of the nominal output signal energy. The test output signal energy is configured so that the maximum energy level of a resulting test return signal is less than the preferred maximum allowable level of 500 watts.”).
Cummings and Cope are analogous to the claimed invention because they are in the same field of endeavor. It would have been obvious to someone of ordinary skill in the art before the effective filing date of the claimed invention to modify the invention of Cummings with the lower-powered test signal of Cope. Cummings notes that channel sounding is necessary for determining self-interference but is silent as to the nature of the test signal used in channel sounding. The lower-powered test signal of Cope would be an obvious choice for a person of ordinary skill in the art to be the channel sounding signal of Cummings because, as Cope teaches, a sounding signal can damage the limiter on the receiver if there is a nearby reflector or damage to the radome (see Cope, col. 3). Using a low-powered signal ensures that sensing is done at full power only when doing so will not damage the receiver. Incorporating the low-powered signal of Cope into the channel sounding of Cummings would have the predictable result of measuring potential near-range interference.
Regarding claim 20, Cummings in view of Wikipedia and further in view of Cope teaches the method of claim 19. Cummings does not teach,
…setting the sense signal to a high power level in the first mode of operation by setting one or more of an amplifier setting, an intermediate frequency gain setting, and an analog-to-digital converter voltage adaptation setting of the radar system.
Cope teaches,
…setting the sense signal to a high power level in the first mode of operation by setting one or more of an amplifier setting, an intermediate frequency gain setting, and an analog-to-digital converter voltage adaptation setting of the radar system (col. 3, lines 57-65, “As will be appreciated, the test return signal presents a low signal strength. Accordingly, the program causes AGC drive 52 and manual gain drive 54 to increase the gains of amplifiers 44 and 46 respectively to gains high enough for accurate analysis. In the preferred embodiment, the gains of amplifiers 44, 46 are adjusted to maximum below saturation.” The examiner notes that the sense signal in the first mode of operation includes both the transmitted and received sense signal; Cope teaches amplifying the received sense signal).
Cummings and Cope are analogous to the claimed invention because they are in the same field of endeavor. It would have been obvious to someone of ordinary skill in the art before the effective filing date of the claimed invention to modify the invention of Cummings with the high-power, amplified received test signal of Cope. Amplifying the received test signal enables the system to use the sensing signal in the first mode to accurately analyze the scene, as noted in the section of Cope cited above. Doing so in the invention of Cummings has the predictable result of enabling use of the sensing signal for accurate analysis.
Claim 30 is rejected for the same reasons and using the same citations as claim 19, above.
Claim 31 is rejected for the same reasons and using the same citations as claim 20, above.
Conclusion
Any inquiry concerning this communication or earlier communications from the examiner should be directed to Anna K Gosling whose telephone number is (571)272-0401. The examiner can normally be reached Monday - Thursday, 7:30-4:30 Eastern, Friday, 10:00-2:00 Eastern.
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/Anna K. Gosling/Examiner, Art Unit 3648
/VLADIMIR MAGLOIRE/Supervisory Patent Examiner, Art Unit 3648
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