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 .
Response to Amendment
The Amendment to the claims filed on 03/10/2026 complies with the requirements of 37 CFR 1.121(c) and has been entered. Objections to Specification and Claims are withdrawn. Claims 1-2, 8-13, 15-19 and 25 are amended. Claims 7, 14 and 20-24 are cancelled.
Response to Arguments
Applicant's Arguments/Remarks filed 03/10/2026 (hereinafter Resp.) are fully considered hereinafter.
Applicant argues that the rejection of Claims 6 and 13 under 35 U.S.C. 112(a) for undue experimentation in the Office Action filed on 12/11/2025 (hereinafter OA) is improper because “[t]he relevant artisan is one skilled in wireless communications and signal processing, not "an ordinary computer programmer" without domain knowledge as the Examiner suggests. Such a skilled artisan would be familiar with standard mathematical transformations such as DFT, DCT, IDFT, and IDCT, which the specification explicitly identifies as suitable transformations for practicing the invention” – See Resp.,9:¶2. However, the rejection specifically refers to the required coding of instructions to perform “calculating beamforming weights” and not to coding of instructions to perform “mathematical transformations” as Applicant argues – See OA,3:¶3 (stating: “the Specification does not disclose any of the mathematical equations behind the operations of calculating beamforming weights in a multi-antennae wireless communications system”)(emphasis added). To be sure, Claims 6 and 13 require a computer program comprising instructions to perform the calculating of beamforming weights (BFWs) of Claims 1 and 8, respectively, not any other calculation known in the art (which would need to be referenced). Without proper support in Claims 1 and 8 and/or the Specification and drawings as to how BFWs are calculated, specifically how “the complex matrix W” is calculated from “the complex matrix H” – See Spec.,7:30-23, be it logical diagram, textual description of the steps involved for this calculation or reference to prior art, claiming a computer program “calculating beamforming weights,” would be against the policy underlying 35 U.S.C. 112(a) – See MPEP § 2162, when every other prior art reference describes such procedure and the claimed invention– transforming the calculated BFWs from frequency-domain to tap-domain by a mathematical transformation– requires “wii, which represents the weight at the i-th row and j-th column of a BFW matrix W” – See Spec.,19:16-25.
Applicant is right that the present disclosure provides, for one of ordinary skills in the art, sufficient support for the meaning of “[t]he mathematical transformations (DFT, DCT, IDFT, IDCT) and the concept of selecting coefficients based on magnitude” – See Resp.,10:¶2. However, the coding of the “transforming, by a mathematical transformation” was not the concern of the §112(a) rejection. Applicant is also right, and the OA agrees, that the disclosure of BFW calculations in Nammi et al., U.S. Patent Application Publication 2020/0052752 (hereinafter Nammi) is an indication of obviousness – See OA, 10:¶1 (stating that: “a programmer of ordinary skills in the art being able to create such computer program on a dearth of disclosure without due experimentation would be an indication of obviousness”). However:
(1) obviousness is a separate legal requirement from the §112(a) requirement explained in the Office action, and
(2) Applicant appreciated such disclosure as necessary in other applications for a US patent on same or similar subject matter filed around the same time this application was filed, that could have been referenced in the present Application – See, e.g., Application #18/280937 (disclosing calculation of BFWs using the channel precoder matrix H and various BFW expressions when applying different functions to the H matrix); Application #18/695447 (disclosing the channel precoder H, the transformation between antennae-space to beams-space precoder W, and formulae for mathematical transformations that are claimed in the present application). This point contradicts Applicant’s argument against the §112(a) rejection, therefore the rejection is maintained.
Applicant further argues that “[b]y reciting ‘a computer program product,’ claims 6 and 13 as amended are now tied to a tangible article of manufacture rather than a computer program per se,” whereby support is found in Spec.,28: 6-14 (stating "[t]he program code mentioned above may also be provided as a computer program product, for instance in the form of a data carrier carrying computer program code for performing the embodiments herein when being loaded into the RU 112”), thus overcoming the rejection under 35 U.S.C. § 101 – See Resp.,11:¶¶1-2. The issue with Applicant’s argument is that “a computer program product” is not an “article of manufacture” under the MPEP and caselaw – See, e.g., MPEP § 2106.03 (I) (stating “Non-limiting examples of claims that are not directed to any of the statutory categories include: Products that do not have a physical or tangible form, such as information (often referred to as "data per se") or a computer program per se (often referred to as ‘software per se’) when claimed as a product without any structural recitations”) (emphasis added); see also Ex parte Mewherter (Appeal 2012-007692) (May 8, 2013) (precedential1) (when Applicant claims “A machine readable storage medium having stored thereon a computer program” and neither the claims nor the specification expressly disclaimed a transitory media, the Board upheld the § 101 rejection and endorsed adding the limitation “non-transitory” to the claim). Here, the Specification explicitly claims supra the transitory nature of the computer program in form of “a data carrier carrying computer program code”, whereby a data carrier is a transitory signal. Therefore, Applicant’s argument is unpersuasive and the rejection is maintained. Furthermore, a computer program is pure software raising the bar for the written description requirement bar under §112(a).
Applicant further argues that because the “amended independent claim 1 recites ‘sending over a fronthaul interface to the RU, the selected one or more the tap-domain BFWs, which selected one or more tap-domain BFWs assist the RU to perform beamforming for the communication between the UE and the base station’ . . . the combined art of record fails to teach or suggest these limitations” – See Resp.,12:¶1.
Regarding the “fronthaul interface” limitation, Applicant agrees that “Nammi teaches BBU-to-RU fronthaul communication” – See id.. In addition, the fronthaul interface has been known to one of ordinary skills in the art since at least the introduction of the split-architecture in 3GPP – See, e.g., § 11.1, 3GPP TR 38.801 V14.0.0 (2017-03), “Technical Specification Group Radio Access Network; Study on new radio access technology: Radio access architecture and interfaces (Release 14)” discussing the functional split CU-DU. Nammi further teaches the Cloud RAN, anopen RAN split architecture well known to one of ordinary skills in the art from standard specifications available before the effective filing date of the present Application – See e.g., O-RAN Alliance, O-RAN Fronthaul Working Group, O-RAN.WG4.CUS.0-v05.00, “Control, User and Synchronization Plane Specification,” published February 2021, (hereinafter O-RAN.WG4.CUS.0-v05.00). Therefore, the argument that the amendment distinguishes from the referenced prior art fails to persuade.
That Brown et al., U.S. Patent Application Publication 2022/0255606 (hereinafter Brown), teaching tap-domain transformation, cannot be properly combined with Nammi because Brown “teaches tap-domain transformation in an entirely different context-UE-to-gNB CSI feedback,” specifically, “the transformation is performed by the UE for CS/feedback to the base station-the opposite communication direction from the claimed BBU-to RU fronthaul transmission” – See Resp., 14:¶3; see also id., 12:¶1 (stating “the combined art of record fails to render present claim 1 obvious in accordance with MPEP 2143”) would be non-analogous art, it has been held that a prior art reference must either be in the field of the inventor’s endeavor or, if not, then be reasonably pertinent to the particular problem with which the inventor was concerned, in order to be relied upon as a basis for rejection of the claimed invention. See In re Oetiker, 977 F.2d 1443, 24 USPQ2d 1443 (Fed. Cir. 1992) (emphasis added). Here, neither the particular problem to be solved (transmission of compressed beamforming weights using frequency-domain precoding vectors) nor the context (BFW matrices in multi-layered/multi-antennae MIMO wireless communications) are so different from Applicant’s endeavor and concerns to be non-obvious to combine or to use the methods of one to improve the other -– See KSR infra. To be sure, the present Specification states that the aim of the proposed invention is to “improve beamforming performance of a wireless communications network” by “compress[ing] the BFWs before transporting them over the fronthaul interface” – See Spec., 4:1-2, and 15-16, based on that the “BFWs transformed e.g. by DCT or DFT to tap-domain has the energy concentrated in a limited number of taps or elements,” i.e., exploit the sparsity of the tap-domain on top of the frequency-domain, so “the BFWs are compressed by selecting taps with larger magnitude such that the transported tap-domain BFWs are fewer than the frequency-domain BFWs before transformation” – See Spec.,11:1-10. Yet Brown also teaches “improved methods for efficiently coding . . . codebook,” i.e., sets of precoder coefficients/BFWs in the context of a wireless communication system by “transforming a set of frequency-domain precoding vectors to generate a set of coefficients in a compressed basis” including “quantizing the compressed basis coefficients depending on their index relative to indices of dominant compressed basis coefficients and the beam” – See [¶0006] by “transform[ing] the set of precoding vectors in the frequency domain to a compressed domain through a linear transformation” based on “the nature of the wireless channel, essentially its sparseness in the time domain,” e.g., by using “discrete Fourier transform (DFT) transformation” – See [¶0036] with application to “Type II codebooks [which] provide high resolution information about current channel conditions and can be used in multi-user MIMO ("MU-MIMO") scenarios” – See [¶0038] wherein “[i]t may be beneficial to feedback weighting coefficients only for those taps with significant energy” and also to “quantize the taps with finer quantization (more quantization levels) for larger transformed precoding coefficient magnitude” – See [¶0067]. Furthermore, not only that Brown describes in detail the mathematical transformation(s) steps but the relevant mathematical transformation in Brown applies to the BFWs (precoder matrices/codebooks), whether they are for the UL or the DL transmission (Brown does not impose one or the other) whereby the calculation of the original BFWs uses the DL channel estimation matrix H – See [¶0049] (“Hn is the . . . baseband channel between the gNB and the UE” wherein “subscript n denotes a subcarrier or sub-band index”), just like the present disclosure describes the “complex matrix H with K rows and N columns of complex values denote the DL channel on one subcarrier” – See Spec., 7:30-32. To be sure, the present disclosure makes no difference between BFWs for the UL or the DL channel, i.e., directionality of transmission between the base station and the UE, as explained infra, and considers that signal/channel/BFWs are each just a “referred quantity,” i.e., an abstraction, in a specific domain – See Spec., 8:10-25, therefore can be mathematically transformed by the same methods. Furthermore, the claimed method performed in “a wireless communications network using a multiple antenna system for communication” wherein the transmitter “transforms by a mathematical transformation, the respective calculated BFWs, from frequency domain BFWs to obtain tap-domain BFWs” and sends “the selected one or more the tap-domain BFWs . . . assists the RU to perform beamforming for the communication between the UE and the base station”– See Spec., 4:24-26, while “transmitting to the RU, only one or more selected tap-domain BFWs for compression purpose” and “the RU may in some embodiments fill zeros and/or pad more zeros on the unselected BFW taps to the received tap-domain BFW” See Spec.,10:24-31, is not different from Brown’s method whereby “the compressed basis is the DFT basis,” i.e., a DFT is the mathematical transformation transforming “the precoding vector W2,r(l) . . . with an inverse Fourier transform” – See [¶0055] and “[i]nstead of reporting an indication of W2,n for all sub-bands n,” i.e., the frequency-domain weights, “[t]he transformation is applied to W2,r(l) for each of 2L beams and each of R layers, forming the transformed vectors w2,r (1)” – See [¶0056] followed by “feeding back an indication of an approximate version of w2,r(l), denoted w^2,r(l) [i.e., the tap-domain coefficients] where all but [a number] of the indices of are zero” because “[t]his indication requires less overhead than that of either the full frequency-domain vectors W2,r(l) or the complete transformed vectors w2,r(l)” – See [¶0058]. Therefore, Applicant’s argument fails to persuade that Brown would be non-analogous art for obviousness purposes. However, in fairness to Applicant’s response, a NPL applying the tap-domain transformation to frequency-domain BFWs at the base station, not at the UE, in further used for the non-obviousness rejection in the present Office action.
Finally, Applicant argues that “one of ordinary skill in the art would not have been motivated to apply Brown's or Fellhauer's UE-side/receiver-side feedback transformation techniques to Nammi's BBU-to-RU fronthaul context because: (1) the communication directions are opposite (uplink feedback vs. fronthaul transmission); (2) the entities performing the transformation are different (UE/receiver vs. BBU); and (3) the problems solved are different (feedback overhead reduction vs. fronthaul capacity reduction)” and that “Examiner's combination improperly relies on hindsight reasoning derived from the claimed invention itself” – See Resp., 15:¶1.
Regarding the directionality argument, the present Specification defeats any claim that UL vs. fronthaul directionality matters in BFWs calculation when stating, on the one hand, that “For the LLS architecture considered according to embodiments herein, channel estimation based on UL reference signals, e.g. Sounding Reference Signal (SRS), and BFW calculation are done in BBU” – See Spec., 17:30-35, and, on the other hand, further explains that the estimated channel matrix H that is used at the BBU to calculate the respective BFWs is in fact a DL channel estimation matrix –See Spec., 7:30-32 (“a KxN complex matrix H with K rows and N columns of complex values denote the DL channel on one subcarrier and the corresponding BFWs is denoted as an NxK complex matrix W with N rows and K columns of complex values”). However, if H is a DL channel precoder matrix as the one known in the art (becauser the Specification does not define H), the DL channel precoder matrix is usually calculated at the UE based on the CSI-RS sent by the base station, as taught in Brown, and not at the BBU based on SRS sent by a UE, as disclosed in the Specification. Because every claim is to be interpreted under the Broadest Reasonable Interpretation, in light of the Specification and drawings, a person of ordinary skills in the art reading the above description would fairly assume a joint UL-DL channel/reciprocal/directional beam(s) communication context wherein the base station has complete knowledge of the channel precoder matrix acquired through any means (e.g., closed loop with the UE or open loop) and this precoder is further processed/mathematically transformed at the BBU to obtain the optimum precoder (the transformed and quantized BFWs in tap domain) that is sent to the RU, noting that the “directionality” and “context” in Nammi combined with Brown are precisely the same as claimed: a BBU calculating the optimum precoder and sending it to the T-RU of the base station for beamforming base station-to-UE transmission. This conclusion is enforced by the way the present Application treats any of the “signal, channel, or BFWs etc.” as “referred quantities” being mathematically treated/transformed – See Spec.,19:22-25 (stating “The transformation is performed regarding L subcarriers of each BFW entry, i.e. wij, which represents the weight at the i-th row and j-th column of a BFW matrix W. For DL beamforming, i=1,. . . ,N and j=1, . . . ,K. For UL beamforming, i=1, . . . ,K and j=1, . . . ,N” making clear that the channel and/or BFWs remain the same for both UL and DL beamforming); see also Nammi:[¶0053] (“Where H is the precoding matrix. If the complete channel knowledge is available at the transmitter, this can then be done using a sounding reference signal or other means,” i.e., at the BBU); whereby “other means” are, e.g., described in Brown:[¶0047](“the remote unit 105 provides CSI feedback to the base unit 110 using a Type II codebook”); [¶0051] (“a closed-loop precoding system the measurement of reference signals transmitted by the gNb enables the UE to estimate the channel matrix Hn over a set of frequencies”); [¶0060] (“the gNB can then obtain the complete precoder recommended by the UE”).
In response to Applicant’s argument that there is no teaching, suggestion, or motivation to combine the references, the examiner recognizes that obviousness may be established by combining or modifying the teachings of the prior art to produce the claimed invention where there is some teaching, suggestion, or motivation to do so found either in the references themselves or in the knowledge generally available to one of ordinary skill in the art. See In re Fine, 837 F.2d 1071, 5 USPQ2d 1596 (Fed. Cir. 1988), In re Jones, 958 F.2d 347, 21 USPQ2d 1941 (Fed. Cir. 1992), and KSR International Co. v. Teleflex, Inc., 550 U.S. 398, 82 USPQ2d 1385 (2007); see also Resp.,13:¶¶1-2 (citing twice to MPEP § 2143 wherein examples of rationales that may support a conclusion of obviousness are discussed in light of KSR ).
Here, the use of a known technique–DFT applied to BFWs–to improve similar methods–transmission of BFWs to a beamforming capable apparatus–in the same way–compression achieved due to energy concentration in a few large taps combined with zero padding of small taps, meets the KSR standard of a prima-facie case of obviousness. the motivation to combine Nammi's BBU-to-RU fronthaul context with the method disclosed in Brown is stated clearly in Nammi: “In frequencies of interest the number of digital chains for massive MIMO (FD-MIMO) can easily be in the range of 64-256 therefore making the burden on the transport network rather difficult to achieve. Without good compression techniques, the throughput requirements for this DU-RU connection can become prohibitively high” – See [¶0018]. Brown teaches precoder compression of frequency-domain BFWs using a tap-domain transformation based on the versatility of chosen DFT basis vectors/matrix.
In response to applicant's argument that the examiner's conclusion of obviousness is based upon improper hindsight reasoning, it must be recognized that any judgment on obviousness is in a sense necessarily a reconstruction based upon hindsight reasoning. But so long as it takes into account only knowledge which was within the level of ordinary skill at the time the claimed invention was made, and does not include knowledge gleaned only from the applicant's disclosure, such a reconstruction is proper. See In re McLaughlin, 443 F.2d 1392, 170 USPQ 209 (CCPA 1971). Here, Applicant’s own argument that “[t]he mathematical transformations (DFT, DCT, IDFT, IDCT) and the concept of selecting coefficients based on magnitude are fundamental signal processing techniques well within the knowledge of one skilled in wireless communications and signal processing” – See Resp., 10:¶2 undermines any presumption of a hindsight. Specifically, the codebook-based/closed loop method for calculating/adjusting the BFWs in Brown does not affect the type and the purpose of the mathematical transformation from frequency BFWs that Brown uses for compression of those BFWs. That tap-domain “quantities” be them signals, channels, or BFWs, are sparser than the same “quantities” in frequency-domain, as known in the art – See, e.g., the figure/diagram of various DFT bases reproduced from Ning infra. And even if an UL non-codebook-based precoding had been claimed, then “the UE has to transmit precoded SRS with a precoder derived from the associated DL CSI-RS resource using beam correspondence,” (i.e., the UE is the first to determine the channel precoder H in order to transmit precoded SRS, as already taught in Brown), incurring delay due to UE’s latency in computing and UL beam selection, hence requiring a tradeoff between loss from compression and compute time – See 3GPP TSG RAN WG1 Meeting #94bis, Title: “On fast SRS precoder updation,” Source: CEWiT, October 2018.
In sum, when like here, a prima-facie case of obviousness had been established, the burden shifts to the Applicant to provide sufficient (a preponderance of) evidence to rebut such a showing – See MPEP § 2145. However, in this case the Applicant did not show any evidence of any secondary considerations (“commercial success, long felt but unsolved needs, [and] failure of others” – See id.) with a corresponding nexus, e.g., between the claimed fronthaul transmission (instead of an over-the-air transmission in prior art) and/or the BBU processing capability to perform the claimed method (instead of a UE’s capability to do the same in prior art) and the secondary consideration. If anything from Applicant’s argument is already apparent to one of ordinary skills in the art is that the conditions of performing the claimed method at the UE side are more difficult than at the BBU side while aiming at the same result: compressing beamforming weights/coefficients in a form understood by both ends of the transmission in order to reduce the bandwidth required for that transmission (not to incur fronthaul capacity reduction, as stated above). Because Applicant has not provided such evidence, the non-obviousness argument fails to persuade. Although the rejections are maintained in this Final Office Action, the cited references have been reviewed to better explain the grounds of rejection in light of Applicant’s Arguments/Remarks.
To conclude, Applicant’s arguments are unpersuasive and the rejections are maintained.
Examiner’s Note: reproduced below are the known mathematical transformation(s) on the matrix bases commonly used for beamforming codebooks/precoder matrices in 3GPP technical specifications (since Release 15) for transforming beamforming matrices from an original space, frequency, or time domain to the sparser domains: angular, delay, and Doppler domains, respectively, making signal/channel/BFWs matrices prone to substantial compression through DFT no matter the original space and no matter the direction of transmission.2, 3,4
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Section 7.5, 3GPP TR 38.901 V16.1.0 (2019-12), “Technical Specification Group Radio Access Network; Study on channel model for frequencies from 0.5 to 100 GHz (Release 16)” shows in Figure 7.5-1, at page 33, the generation procedure of a channel estimation matrix coefficients (the BFWs corresponding to precoder H) when a Fast-Fading model is used, as reproduced below, stating that although “downlink is assumed. For uplink, arrival and departure parameters have to be swapped,” in a case where coefficients are calculated the beam-space domain. Fading channel models are largely used in MIMO systems – See, e.g., Maruta et al., “Multiuser Parallel Transmission with 1-Tap Time Domain Beamforming by Millimeter Wave Massive Antenna Arrays” Global Journal of Computer Science and Technology: A Hardware & Computation, Volume 16 Issue 2 Version 1.0 Year 2016, Publisher: Global Journals Inc. (USA) Online ISSN: 0975-4172 & Print ISSN: 0975-4350, describing at page 4 “the spatial relationships between the UEs and the BSs” using “the channel matrix per subcarrier, H” in formulae (1) and (2) when “[a]ssuming multicarrier transmission such as orthogonal frequency division multiplexing (OFDM)” and a “Rician fading channel.”
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Annex K, O-RAN.WG4.CUS.0-v05.00, describes, at page 277, an example of 48 array elements in 4 layers with four data converters whereby each “converter connects to all the 48 array elements (also known as the full connection model in 3GPP),” each “array element contains 4 gain and phase control elements” wherein “gain and phase control element is used to apply time domain (TD) beamforming weights” and “can be beamformed with a 48 element TD beamforming vector (θq,0, θq,47) and a Frequency Domain (FD) beamforming weight φ𝑞 corresponding to layer 𝑞. Each array element hence can receive 4 equivalent beamforming weights φ0 θ0,0 to φ3 θ3,0 corresponding to 4 layers”; see also § 6.1.3.2, at page 137, defining gain of one Tx-RX antenna element over the Fronthaul Interface, stating that for “O-RUs supporting beamforming, the actual DL gain and UL gain of the array element can be impacted by the gain level of beam weight used and which can change dynamically during operation,” referencing 3GPP TS 36.141 V17.1.0 (2021-03) “Technical Specification Group Radio Access Network; Evolved Universal Terrestrial Radio Access (E-UTRA); Base Station (BS) conformance testing (Release 17)” wherein Annex B.5, at page 431, describe Multi-Antenna channel models and “MIMO channel correlation matrices” that apply for “the antenna configuration using uniform linear arrays at both UE and eNodeB” and are referenced in determining the optimum precoder for the channel between the base station and the UE.
End of Examiner’s Note.
Double Patenting
The nonstatutory double patenting rejection is based on a judicially created doctrine grounded in public policy (a policy reflected in the statute) so as to prevent the unjustified or improper timewise extension of the “right to exclude” granted by a patent and to prevent possible harassment by multiple assignees. A nonstatutory double patenting rejection is appropriate where the conflicting claims are not identical, but at least one examined application claim is not patentably distinct from the reference claim(s) because the examined application claim is either anticipated by, or would have been obvious over, the reference claim(s). See, e.g., In re Berg, 140 F.3d 1428, 46 USPQ2d 1226 (Fed. Cir. 1998); In re Goodman, 11 F.3d 1046, 29 USPQ2d 2010 (Fed. Cir. 1993); In re Longi, 759 F.2d 887, 225 USPQ 645 (Fed. Cir. 1985); In re Van Ornum, 686 F.2d 937, 214 USPQ 761 (CCPA 1982); In re Vogel, 422 F.2d 438, 164 USPQ 619 (CCPA 1970); In re Thorington, 418 F.2d 528, 163 USPQ 644 (CCPA 1969).
A timely filed terminal disclaimer in compliance with 37 CFR 1.321(c) or 1.321(d) may be used to overcome an actual or provisional rejection based on nonstatutory double patenting provided the reference application or patent either is shown to be commonly owned with the examined application, or claims an invention made as a result of activities undertaken within the scope of a joint research agreement. See MPEP § 717.02 for applications subject to examination under the first inventor to file provisions of the AIA as explained in MPEP § 2159. See MPEP § 2146 et seq. for applications not subject to examination under the first inventor to file provisions of the AIA . A terminal disclaimer must be signed in compliance with 37 CFR 1.321(b).
The filing of a terminal disclaimer by itself is not a complete reply to a nonstatutory double patenting (NSDP) rejection. A complete reply requires that the terminal disclaimer be accompanied by a reply requesting reconsideration of the prior Office action. Even where the NSDP rejection is provisional the reply must be complete. See MPEP § 804, subsection I.B.1. For a reply to a non-final Office action, see 37 CFR 1.111(a). For a reply to final Office action, see 37 CFR 1.113(c). A request for reconsideration while not provided for in 37 CFR 1.113(c) may be filed after final for consideration. See MPEP §§ 706.07(e) and 714.13.
The USPTO Internet website contains terminal disclaimer forms which may be used. Please visit www.uspto.gov/patent/patents-forms. The actual filing date of the application in which the form is filed determines what form (e.g., PTO/SB/25, PTO/SB/26, PTO/AIA /25, or PTO/AIA /26) should be used. A web-based eTerminal Disclaimer may be filled out completely online using web-screens. An eTerminal Disclaimer that meets all requirements is auto-processed and approved immediately upon submission. For more information about eTerminal Disclaimers, refer to www.uspto.gov/patents/apply/applying-online/eterminal-disclaimer.
Claims 8-13, as amended, are rejected on the ground of nonstatutory double patenting as being unpatentable over claims 1-5 of U.S. Patent No. 12,567,893 (hereinafter ‘893).
CLM.
Present Application
CLM.
‘893 Patent
8
A method performed by a Radio Unit, RU, for performing beamforming for a communication between a User Equipment, UE, and a base station in a wireless communications network using a multiple antenna system for
communication, wherein the RU is associated with the base station, the method comprising:
1
A method performed by a Radio Unit, RU, (112) for performing beamforming for a communication between a User Equipment, UE, (120) and a base station (110) in a wireless communications network (100) adapted to use a multiple antenna system for communication, wherein the RU (112) is associated with the base station (110), the method comprising:
receiving over a fronthaul interface from a Base Band Unit, BBU, associated with the base station, one or more tap-domain BFWs selected by the BBU
receiving (401) from a Base Band Unit, BBU, (111) associated with the base station (110), via a fronthaul
interface, a subset of channel taps selected by the BBU (111) from a larger set of channel taps to reduce required fronthaul capacity,
and information identifying the selected subset of channel taps to enable reconstruction of the channel taps in the tap domain;
reconstructing tap-domain BFWs based on the selected one or more tap-domain BFWs,
reconstructing (402) the channel taps in the tap domain by using the information identifying the selected subset of channel taps to determine positions of the selected channel taps within a complete set of channel taps;
transforming by a mathematical transformation, at least some of the reconstructed tap-domain
BFWs of the one or more tap-domain BFWs,
transforming (403) by a mathematical transformation comprising an inverse discrete Fourier transform (IDFT) or inverse discrete cosine transform (IDCT), at least some of the channel taps out of the set of channel taps,
to obtain corresponding frequency domain channel values related to respective subcarriers out of a
number of subcarriers;
to obtain corresponding frequency domain BFWs related to respective subcarriers out of a number of subcarriers, and
determining (404) respective Beamforming Weights, BFWs, according to the obtained frequency domain channel values, on the respective subcarriers out of the
number of subcarriers; and
performing beamforming with the obtained frequency domain BFWs on the respective subcarriers out of the number of subcarriers for the communication between the UE and the base station.
performing (405) beamforming with the determined BFWs on the respective subcarriers out of the number of subcarriers for the communication between the UE
(120) and the base station (110).
9
The method according to claim 8, wherein the receiving from the
BBU, further comprises:
receiving information identifying the selected one or more tap-domain BFWs.
10
The method according to claim 8, wherein the reconstructing of the
tap-domain BFWs of the selected one or more tap-domain BFWs further comprises any one or more out of:
2
The method according to claim 1, wherein the reconstructing (402) the channel taps in the tap domain,
filling zeros at the positions of frequency domain BFWs that are unselected according to the received information identifying the selected one or more tap-domain BFWs, and
filling zeros at in the end of the tap-domain BFWs.
is performed by filling zeros at the positions of the unselected channel taps according to the received information identifying the selected subset of channel taps.
11
The method according to claim 8, further comprising:
3
The method according to claim 1, wherein the determining (404) of the respective BFWs according to the
obtained frequency domain channel values, on the respective subcarriers out of the number of subcarriers comprises:
calculating BFWs according to the obtained frequency domain channel values for at least part of the respective subcarriers out of the number of subcarriers; and
when frequency domain BFWs has not been obtained on all subcarriers obtaining frequency domain BFWs on the remaining subcarriers out of the number of subcarriers based on the transformed frequency domain BFWs.
if not BFW s on all subcarriers of the number of subcarriers has been calculated, obtaining BFWs on the remaining sub-carriers based on the calculated BFWs.
12
The method according to claim 11, wherein the obtaining of the
frequency domain BFW s on the remaining subcarriers out of the number of subcarriers based on
the transformed frequency domain BFWs, is performed by any one or more out of:
4
The method according to claim 3, wherein the BFWs on the remaining subcarriers are obtained by anyone or more out of:
repeating the corresponding frequency domain BFWs on neighboring subcarriers.
repeating the calculated BFWs for neighboring sub-carriers of the remaining sub-carriers; and
interpolating the corresponding frequency domain BFWs. . . .
interpolating the calculated BFW s for the remaining subcarriers.
13
A computer program product comprising a computer program comprising instructions, which when executed by a processor, causes the processor to perform actions according to claim 8.
5
A computer program (1080) comprising instructions, which when executed by a processor (1060), causes the processor (1060) to perform actions according to claim 1.
Although the method of Claim 8 in the present Application and that of Claim 1 in the ‘893 Patent differ in that starts the latter starts from channel taps, whereby each tap corresponds to all subcarriers in the channel band, and the former starts from tap-domain BFWs, these two concepts are technically analogous – See Spec., 10:1-16 (stating the “term of tap-domain BFWs used here takes the analogy of the relation between the frequency-domain channel and the tap-domain channel” and that a “BFW tap . . . means each BFW value obtained from the mathematical transformation, e.g. DCT or DFT, of frequency-domain BFWs . . . for a given antenna element, or beam, after the mathematical transformation of the frequency domain BFWs”). Since the method of the ‘893 Patent obtains BFWs from channel taps through the same type of mathematical transformations as applied to tap-domain BFWs, the channel taps are a species of BFWs taps when limiting both channel taps and tap-domain BFWs to the same discrete set of subcarriers5, i.e., applying the methods to the same RB(s) transmitted on “one path between a UE antenna and an antenna or a beam at the base station along the subcarriers within a continuous bandwidth” – See Spec., 8:26-27 and Figure 2. To be sure, the method in Claim 8 of the present Application supports broader beam related attributes/values because “signal, channel, BFW etc.” as just “quantities,” that may be “defined at different frequencies” (i.e., may be “multidimensional … where each dimension corresponds to one frequency”) while each (multidimensional) quantity, is associated either with each antenna element/array/port or with each pre-defined beam – See Spec., 8:18-25. Therefore, Claim 8 of the present Application is generic to (broader than) Claim 1 of the ‘893 Patent which anticipates it or, in the alternative, is an obvious variant of it.
Claims 1-5 of the ‘893 Patent also anticipate Claims 9-13 of the present Application for reasons apparent from the table shown above.
In sum, Claims 8-13, as amended, are rejected for Nonstatutory Double Patenting over the ‘893 Patent issued to the same Assignee.
Drawings
The drawings are objected to because they are identified as Fig. 1 to Fig. 17, while the Specification references Figure 1 to Figure 17.. Corrected drawing sheets in compliance with 37 CFR 1.121(d) are required in reply to the Office action to avoid abandonment of the application. Any amended replacement drawing sheet should include all of the figures appearing on the immediate prior version of the sheet, even if only one figure is being amended. The figure or figure number of an amended drawing should not be labeled as “amended.” If a drawing figure is to be canceled, the appropriate figure must be removed from the replacement sheet, and where necessary, the remaining figures must be renumbered and appropriate changes made to the brief description of the several views of the drawings for consistency. Additional replacement sheets may be necessary to show the renumbering of the remaining figures. Each drawing sheet submitted after the filing date of an application must be labeled in the top margin as either “Replacement Sheet” or “New Sheet” pursuant to 37 CFR 1.121(d). If the changes are not accepted by the examiner, the applicant will be notified and informed of any required corrective action in the next Office action. The objection to the drawings will not be held in abeyance.
The drawings are further objected to under 37 CFR 1.83(a) because:
Fig. 1 (identified as Figure 1 in the Specification at page 3) fails to show "high burst fronthaul traffic due to BFWs" as described in the Specification;
Fig. 2 (identified as Figure 2 in the Specification at page 6) is not “a schematic block diagram illustrating embodiments of a wireless communications network”;
Fig. 3 (identified as Figure 3 in the Specification at page 6) is not “a sequence diagram”;
Figs.7-9 (identified as Figures 7-9 in the Specification at page 6) show measurement results rather than “a diagram illustrating an example embodiment herein.”
Any structural detail that is essential for a proper understanding of the disclosed invention should be shown in the drawing. MPEP § 608.02(d). Corrected drawing sheets in compliance with 37 CFR 1.121(d) are required in reply to the Office action to avoid abandonment of the application. Any amended replacement drawing sheet should include all of the figures appearing on the immediate prior version of the sheet, even if only one figure is being amended. The figure or figure number of an amended drawing should not be labeled as “amended.” If a drawing figure is to be canceled, the appropriate figure must be removed from the replacement sheet, and where necessary, the remaining figures must be renumbered and appropriate changes made to the brief description of the several views of the drawings for consistency. Additional replacement sheets may be necessary to show the renumbering of the remaining figures. Each drawing sheet submitted after the filing date of an application must be labeled in the top margin as either “Replacement Sheet” or “New Sheet” pursuant to 37 CFR 1.121(d). If the changes are not accepted by the examiner, the applicant will be notified and informed of any required corrective action in the next Office action. The objection to the drawings will not be held in abeyance.
Corrected drawing sheets in compliance with 37 CFR 1.121(d) are required in reply to the Office action to avoid abandonment of the application. Any amended replacement drawing sheet should include all of the figures appearing on the immediate prior version of the sheet, even if only one figure is being amended. The figure or figure number of an amended drawing should not be labeled as “amended.” If a drawing figure is to be canceled, the appropriate figure must be removed from the replacement sheet, and where necessary, the remaining figures must be renumbered and appropriate changes made to the brief description of the several views of the drawings for consistency. Additional replacement sheets may be necessary to show the renumbering of the remaining figures. Each drawing sheet submitted after the filing date of an application must be labeled in the top margin as either “Replacement Sheet” or “New Sheet” pursuant to 37 CFR 1.121(d). If the changes are not accepted by the examiner, the applicant will be notified and informed of any required corrective action in the next Office action. The objection to the drawings will not be held in abeyance.
Claim Objections
Amended Claim 10 is objected to because of the following informalities: the claim should depend on Amended Claim 9 to avoid a lack of antecedent rejection when “the received information identifying the selected one or more tap-domain BFWs” is required. Appropriate correction is required.
Amended Claim 11 is objected to because of the following informalities: “BFWs has not been obtained” should be “BFWs have not been obtained.”
Claim Rejections - 35 USC § 112(a)
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.
Amended Claims 6 and 13 are rejected under 35 U.S.C. 112(a) as failing to comply with the sufficient written description and enablement requirement. The claims contain 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.
Regarding Amended Claims 6 and 13, while it is true that a skilled artisan would be familiar with standard mathematical transformations such as DFT, DCT, IDFT, and IDCT, which the specification explicitly identifies as suitable transformations for practicing the invention, and such transformations would be available as mathematical libraries for a computer program developer, the claim language also requires coding of instructions to perform the step of “calculating beamforming weights” specifically for a communication between the base station and the UE, as recited in Amended Claim 1. However, there is no support in the disclosure regarding how these weights are calculated so that a person of ordinary skills in the art of computer programming could reasonably use to code the instructions.
For example, the Specification only discloses that “channel estimation based on UL reference signals, e.g. Sounding Reference Signal (SRS), and BFW calculation are done in a BBU” – See Spec., 7:11-12 and that “frequency domain BFWs may first be calculated based on the frequency channel data” – See Spec., 10:6-7 and Figure 4 showing the “Calculate respective BFWs” step of the BBU method, and no intimation of what “the frequency channel data” could mean. Under the broadest reasonable interpretation, the examination proceeds with the assumption that “channel estimation based on UL reference signals” comprises data regarding channel model in frequency domain. It is also noted that while the Specification mentions a channel precoding matrix H and a BFWs matrix W with no support as to where they come from: the art or an application specific calculation– See Spec., 7:30-32 (stating “a KxN complex matrix H with K rows and N columns of complex values denote the DL channel on one subcarrier and the corresponding BFWs is denoted as an NxK complex matrix W with N rows and K columns of complex values”). This is problematic for several reasons:
(1) while in the art W is usually calculated based on H, both the method of calculation and the composition of W vary largely based on the MIMO environment and the DFT bases chosen, hence just naming these matrices in the Specification is not sufficient to indicate the method used for the calculation of W;
(2) there is no intimation in the present disclosure that the complex matrices H and W are indeed those known in the art, hence just naming these matrices in the Specification is not sufficient to identify them with prior art;
(3) as shown above, the Specification supports a complex matrix H associated with the DL channel on one subcarrier; however, if H is a DL channel precoder matrix as the one known in the art, the DL channel precoder matrix is calculated (mainly) at the UE based on the CSI-RS sent by the base station, as taught in Brown, and not at the BBU based on SRS sent by a UE as supported by the present Specification – See Spec., 17:30-35 (stating “For the LLS architecture considered according to embodiments herein, channel estimation based on UL reference signals, e.g. Sounding Reference Signal (SRS), and BFW calculation are done in BBU. Then BBU transports the BFWs to the RU. The RU receives the BFWs and use the BFWs to execute downlink (DL) or uplink (UL) beamforming”); thus, a person of ordinary skills in the art is not reasonably appraised as to how the UL channel is precoded from the DL channel estimation.
Beyond lack of support for the assumptions a person of ordinary skills should make to arrive at the present invention, Claim 6 requires a computer program, i.e., software/code, comprising instructions for calculating those BFWs and written description requirements are more stringent in such subject matter – See, e.g., MPEP § 2161.01(I) (stating that “original claims may lack written description when the claims define the invention in functional language specifying a desired result but the specification does not sufficiently describe how the function is performed or the result is achieved. For software, this can occur when the algorithm or steps/procedure for performing the computer function are not explained at all or are not explained in sufficient detail (simply restating the function recited in the claim is not necessarily sufficient). In other words, the algorithm or steps/procedure taken to perform the function must be described with sufficient detail so that one of ordinary skill in the art would understand how the inventor intended the function to be performed); see also MPEP §§ 2163.02 and 2181(IV). For example, where the specification provides in a block diagram disclosure of a complex system that includes a microprocessor and other system components controlled by the microprocessor, a mere reference to a commercially available microprocessor, without any description of the precise operations to be performed by the microprocessor, fails to disclose how such a microprocessor would be properly programmed to (1) either perform any required calculations or (2) coordinate the other system components in the proper timed sequence to perform the functions disclosed and claimed – See MPEP §2164.06(c)(I).
Here, Amended Claims 6 and 13 each requires a computer program comprising instructions containing the logic and mathematical calculation of beamforming weights for a base station using multiple antennae to communicate with a UE when such calculation requires wireless communications specific advanced Digital Signal Processing stretching well beyond the common knowledge and skills of an ordinary computer programmer, basically requiring the programmer to also be skilled in the arts of advanced mathematics and wireless channel modeling in frequency domain. The Specification neither discloses how to perform calculating beamforming weights in a multi-antennae wireless communications system, nor points to prior art for such teaching6. Thus, the specific subject matter of calculating the BFWs to perform beamforming for a communication between a User Equipment and a base station, as claimed, 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, at the time the application was filed, had possession of the claimed invention.
In the alternative that a programmer of ordinary skills in the art is able to create such computer program on a disclosure of just the “Kx N complex matrix H with K rows and N columns of complex values denote the DL channel on one subcarrier and the corresponding BFWs is denoted as an NxK complex matrix W with N rows and K columns of complex values,” – See Spec., 7:30-33 (emphasis added) based on H and W being precoding matrices known in the art, that would be an indication of obviousness.
In sum, Amended Claims 6 and 13 are rejected under 35 U.S.C. 112(a) for lack of written description.
Claim Rejections - 35 USC § 101
35 U.S.C. 101 reads as follows:
Whoever invents or discovers any new and useful process, machine, manufacture, or composition of matter, or any new and useful improvement thereof, may obtain a patent therefor, subject to the conditions and requirements of this title.
Amended Claims 6 and 13 are rejected under 35 U.S.C. §101 because they fail to recite patent eligible subject matter.
Regarding Amended Claims 6 and 13, dependent from the methods recited in Amended Claims 1 and 8, each claimed invention is directed to “a computer program product” which is not a statutory category under §101 – See MPEP § 2106.03 (I) (stating “Non-limiting examples of claims that are not directed to any of the statutory categories include: Products that do not have a physical or tangible form, such as information (often referred to as "data per se") or a computer program per se (often referred to as ‘software per se’) when claimed as a product without any structural recitations”) (emphasis added); see also Ex parte Mewherter (Appeal 2012-007692) (May 8, 2013) (precedential) (when Applicant claims “A machine readable storage medium having stored thereon a computer program” and neither the claims nor the specification expressly disclaimed a transitory media, the Board upheld the § 101 rejection and endorsed adding the limitation “non-transitory” to the claim). Here, the Specification explicitly claims supra the transitory nature of the computer program in form of “a data carrier carrying computer program code”, whereby a data carrier is a transitory signal.
Therefore, Amended Claims 6 and 13 are rejected under 35 U.S.C. § 101 as reciting a non-statutory subject matter.
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.
This application currently names joint inventors. In considering patentability of the claims the examiner presumes that the subject matter of the various claims was commonly owned as of the effective filing date of the claimed invention(s) absent any evidence to the contrary. Applicant is advised of the obligation under 37 CFR 1.56 to point out the inventor and effective filing dates of each claim that was not commonly owned as of the effective filing date of the later invention in order for the examiner to consider the applicability of 35 U.S.C. 102(b)(2)(C) for any potential 35 U.S.C. 102(a)(2) prior art against the later invention.
Claims 1-6, and 15-19, as amended, are rejected under 35 U.S.C. §103 as being unpatentable over Nammi et al., U.S. Patent Application Publication 2020/0052752 (hereinafter Nammi) and further in view of Maruta et al., “Multiuser Parallel Transmission with 1-Tap Time Domain Beamforming by Millimeter Wave Massive Antenna Arrays” Global Journal of Computer Science and Technology: A Hardware & Computation, Volume 16 Issue 2 Version 1.0 Year 2016, Publisher: Global Journals Inc. (USA) Online ISSN: 0975-4172 & Print ISSN: 0975-4350 (hereinafter Maruta).
Regarding Amended Claims 1 and 15, Nammi teaches a baseband unit and a method performed by a Baseband Unit, BBU (as shown in Figs. 1 and 2, wherein “the network node 106 can be part of a split radio access network comprising two or more units,” e.g., “a distributed baseband unit (DU) 204 that performs lower level MAC and physical layer functionality, and a remote radio unit (RU) 206 that can transmit and receive RF signals and converts analog signals to digital signals and vice versa,”– See [¶0035]),
for assisting a Radio Unit, RU, to perform beamforming for a communication between a User Equipment, UE, and a base station in a wireless communications network using a multiple antenna system for communication (a “split radio access network that efficiently transmits beamforming coefficients from a distributed baseband unit device to a remote radio unit device to facilitate beamforming at the remote radio unit” having “large number of antenna ports” and “performing the digital beamforming at the remote radio unit device” whereby “[t]he beamforming coefficients can . . . be determined at the baseband unit device” – See [¶0016] by “determin[ing] the best precoder matrix from the estimated channel from the uplink. Once it determines the channel it will find the coefficients for the linear combination of the basis vectors which are known at the distributed baseband unit as well as at the remote radio unit” – See [¶0017] and at the RU, the “digital beamforming block uses the beam forming coefficients along with a basis vector matrix to perform the beamforming on each kth data stream corresponding to P antenna ports” – See [¶0046]; furthermore, “[a]t massive MIMO base stations, signal-processing algorithms plot the best transmission route through the air to each user” to “send individual data packets in many different directions, bouncing them off buildings and other objects in a precisely coordinated pattern” in the beam-space, so that “a data stream can be used to generate multiple data streams, each corresponding to an antenna port, and the data streams can each be modified based on a beamforming vector” – See [¶0038]) (emphasis added to show the difference between a beam’s path and a channel as a data path7 [i.e., set of subcarriers or reserved PRBs] between a transmitter antenna/port and receiver antenna, i.e., a beam-space/domain and a frequency-space/domain)
wherein the BBU and the RU are associated with the base station (a “network node 106 can be part of a split radio access network comprising two or more units” whereby “[e]ach of the CU 202, DU 204, and RU 206 can be linked via a fiber optical network or other high bandwidth front haul network” – See [¶0036] and Figs. 1-2; see also Fig. 3 wherein the “[d]emarcation line 330 can indicate the activities which above the line 330 are performed at the baseband unit, while the activities below the line 330 are performed at the remote radio unit” – See [¶0042])
the method comprising:
calculating respective Beamforming Weights, BFWs, for at least a subset of subcarriers out of a number of subcarriers (“obtaining, by a baseband unit device comprising a processor, beamforming coefficients that are able to facilitate beamforming, by a remote radio unit device of a transmission to be sent to a user equipment device, wherein the beamforming coefficients correspond to respective basis vectors,” i.e., the basis vectors may be chosen in the beam domain or the frequency domain, and “obtaining, by the baseband unit device, a spectral efficiency for combinations of portions of the beamforming coefficients,” i.e., transforming from beam-domain to frequency-domain to calculate spectral efficiency – See [¶0023] and Equation (1), wherein “for each antenna port P there is a set of beamforming coefficients α and θ [the BFWs] that are used, in conjunction with the corresponding basis vector, to digitally beamform the data stream that corresponds to the port” – See [¶0051] and whereby if “L is the number of layers [e.g., UEs] associated with the data, and F tones [a subset of subcarriers out of the number of subcarriers in the band] before beamforming A=LxF matrix” then “[a]fter beamforming, the IQ data has P ports (each antenna) and F tones (B=PxF matrix),” i.e., the BBU calculates the BFWs matrix P28,9 “[a]s a PxL matrix where the rows of the matrix correspond to the number of ports, and columns correspond to the number of layers” – See [¶0039] and “the beamforming coefficients are compressed by adaptively quantizing each column of the beamforming matrix P2” – See [¶0039]; furthermore, for each layer/UE, i.e., “[e]ach column of P2 can be decomposed into a linear combination of certain basis vectors,” which are “the columns of a PxP orthonormal matrix,” e.g., a “size P Fourier matrix” – See [¶0048] whereby the BFWs are “the modifiers that weight the already known V, which is the basis vector/matrix that is known to both the DU and the RU. Vk is the kth column of the basis matrix” corresponding to the kth antenna port at the RU – See [¶0051] (emphasis added on the basis vectors because they define the original space for BFWs as explained in Examiner’s Note supra noting that, and “the α and θ elements can be the beamforming coefficients, or the modifiers that weight the already known V” are not limited to the spatial-domain as defined for the Fast Fading channel model in 3GPP TS 38.901 supra, but can be extended to a frequency-domain when the basis vector matrix is chosen in that domain, as explained in Maruta infra); furthermore, the channel precoding matrix H for a MIMO with 8 antennae/ports at the BS RU – See [¶0049] is used to calculate the respective BFWs of the corresponding F tones channel between the BS and a UE10, and “can be written H=[h1, h2, ….h8]” – See [¶0055] and “hk is an n x 8 MIMO channel across the TxRUs of the kth. . . port” wherein n is the number of subcarriers of the channel continuous bandwidth– See [¶0056]; here, is assumed “complete channel knowledge . . . at the transmitter, this can then be done using a sounding reference signal,” e.g., SRS sent from each UE as further explained infra – See [¶0053] i.e., the BBU and the UE have already perfected the channel precoder matrix H; then “a distributed baseband unit device can determine the best precoder matrix from the estimated channel from the uplink” and after “it determines the channel [ precoding matrix H] it will find the coefficients for the linear combination of the basis vectors which are known at the distributed baseband unit as well as at the remote radio unit,” i.e., determines the BFWs and send only “the beamforming coefficients for the portion of basis vectors that give the best spectral efficiency and/or throughput metrics”– See [¶0017]; finally, “we can minimize the representation of P2 based on port mapping,” e.g., “each . . . port can be mapped only on the all the co-polarized elements of a column, therefore P2 can be written as” a matrix wherein the numbers sitting on the diagonal are exactly the eigenvalues of the matrix – See [¶0054] and also “create a partial covariance matrix of the MIMO channel H as” a matrix wherein the numbers sitting on the diagonal are exactly the eigenvalues of the matrix indicating the strongest – See [¶0055] therefore, “the optimum precoder for the kth . . . P2k port is given by the dominant Eigenvector of [the covariance matrix of the MIMO channel H] as shown below in Equation 6”– See [¶0057] as the Singular Value Decomposition (SVD) basis of each independent spatial path – See [¶0058] (“the main principle is to compute the SVD for each column and formulate the beamforming matrix”))
selecting one or more each vector P2k can be expresses as a linear combination of the [frequency-domain DFT] basis vectors . . . the DU can compress the coefficients αk,l for each P2k,” i.e., the frequency domain BFWs, and “can further compress the signaling between the DU and RU by choosing only 'M' values of αk,l for each P2k” – See [¶0060] “which gives best . . . spectral efficiency” – See [¶0063]; this “method can also be described thusly” as the BBU selecting “respective subgroups of beamforming coefficients that correspond to respective basis vectors”; in addition, “[t]he baseband unit device can also select a portion of the subgroups of beamforming coefficients with a highest spectral efficiency of the portions of the subgroups of the beamforming coefficients to add to a reduced size group of beamforming coefficients” – See [¶0064] and “[a] selection component 506 can be included that is configured to compute spectral efficiencies associated with portions of the subgroups of beamforming coefficients,” e.g., “based on the significance of the coefficients” – See [¶¶0069-70]), and
sending over a fronthaul interface to the RU, the selected one or more the beamforming weights are calculated at the digital baseband unit, and transmitted across a wired network to the radio unit, also known as the fronthaul” – See [¶0019]; “The baseband unit device can also transmit the reduced size group of beamforming coefficients to a remote radio unit device to facilitate digital beamforming of a transmission to occur at the remote radio unit device” – See [¶0064], e.g., “transceiver component 508 can be provided to transmit the compressed group of beamforming coefficients to a remote radio unit device to facilitate digital beamforming of a transmission to occur at the remote radio unit device” – See [¶0071] and “[o]nce the remote radio unit receives the compressed coefficients, it will reconstruct the precoder matrix” – See [¶0017], e.g., the “remote radio unit can then reconstruct the beamforming matrix using” Equation 2 – See [¶0049] and “the remote radio unit can perform digital beamforming 322, IFFT/CP addition 324, Digital to analog conversion 326, and then perform analog beamforming 328 before transmitting the data to the UE” – See [¶0043] and Figs. 3 and 4).
Although Nammi is concerned that “[w]ithout good compression techniques, the throughput requirements for this DU-RU connection can become prohibitively high” – See [¶0018] disclosing some compression techniques but not excluding others, just like not imposing that the DFT basis vectors be in the beam space domain or frequency domain, as explained above, Nammi does not teach:
Transforming, by a mathematical transformation, the respective calculated BFWs, from frequency domain BFWs to obtain tap-domain BFWs, and
selecting and sending one or more tap-domain BFWs quantized (as already taught in Nammi – See [¶0049] (“the baseband unit quantizes and sends”) from said obtained tap-domain BFWs to the RU (instead of sending the beamforming coefficients with a highest spectral efficiency over the fronthaul interface to the RU).
Maruta discloses a fading channel model in a MIMO system with Line-of-Sight (LoS)
dominant channel – Abstract and Figure 1, wherein a “BS is composed of Na SAs, each of which has Nt elements in a uniform planar array (UPA)” and each “SA serves one UE with Nr UPA elements via beamforming; only a single stream is allocated to each UE” – See § II(a), at page 3-4. Like the H precoder matrix from complete channel knowledge described in Nammi:[¶¶0053-54] and Equation 5, the channel matrix per subcarrier H in Maruta is composed of Hi vectors where each Hi “denotes the channel sub matrix between the i-th UE and BS” and “The i-th UE and SA perform beamforming only to each other as an isolated system” – See § II(b), p.4 (the ith UE here corresponds to the lth layer of the 1 . . . L layers in Nammi, and each SA corresponds to one port of the 1. . . P in Nammi when single stream transmission is assumed11). Then “[w]ith the LoS dominant channel, it is expected that the 1st eigenmode weight vectors uj H and vi attain beamforming gain by extraction of the LoS component” – See id., because “[g]iven the
LoS environment, 1st eigenvalue usage is outstandingly effective since its transmission/reception beams are much more stable than those for 2nd and higher order eigenmodes” using “block diagonalization (BD) or singular value decomposition (SVD) computations of large-scale matrices for each frequency component” – See §I, p.3, col1; see also Maruta2 in Footnote 6, referenced by Maruta at [9] (stating at page 5 that the “BS calculates the precoding weight via BD” and “the transmission/reception weight for the 1st eigenmode steers the beam so as to obtain large gain. It extracts the path for the stable LoS component and, by comparison, suppresses NLoS components that have extremely strong time variation characteristics” and at page 12 that because “UEs are spatially de-correlated, 1st eigenmodes can keep their high gain
and thus higher spectral efficiency is achieved”); in accord with “the optimum precoder for the kth CSI-RS P2k port is given by the dominant Eigenvector of” the “covariance matrix of the MIMO channel H,” and as taught in Nammi: [¶¶0056-57] and “choose α and θ which gives the best . . . spectral efficiency . . . and then the precoder vector can be constructed from the chosen alpha values and the basis vectors” – See Nammi: [¶0063].
Maruta further teaches:
transforming by a mathematical transformation, the respective calculated BFWs, from frequency domain BFWs to obtain tap-domain BFWs (when using “LoS dominant channel such that the first eigenmode reception weight can be approximately obtained as the simple reception weight determined for the case in which only a single antenna element located around the center of the array antenna at UE side transmits a training signal for channel estimation . . . the subsequent application of TDBF makes accurate weight estimation under such condition possible” whereby the “Fourier transformation of the constant weight in the frequency domain yields an impulse shaped tap coefficient in the time domain, i.e. a 1-tap TDBF weight” – See § III, p. 4-5, col1, whereby 1-tap time domain beamforming (TDBF) “can be applied to all frequency components,” i.e., subcarriers selected from the frequency domain and “can still strengthen the dominant arriving path” – See §I, p.3, col2) and
selecting one or more tap-domain BFWs from said obtained tap-domain BFWs (e.g., the obtained 1-tap TDBF weight for the 1st eigenmode vector, i.e., the optimum precoder P2k allocated to the UE for a selected subcarrier/subband in Nammi, obtained after “block diagonalization (BD) or singular value decomposition (SVD) computations of large-scale matrices for each frequency component” – See §I, p.3, col1; accord with Nammi:[¶¶0054-56]), and
sending After obtaining an adequate transmission weight at BS side,”– See § III, p. 5, col1, the “SA [i.e., the RU] applies the TDBF weight and transmits a training signal to UE” and “reciprocity calibration . . . is required to obtain the transmission weight from the reception weight since uplink and downlink signals go through different circuits” – See id., col2).
Thus, Nammi and Maruta each describes beamforming techniques in a MIMO system using precoding matrices containing beamforming coefficients/weights (BFWs) corresponding to dominant LOS beam per pair of BS antenna port – UE antenna and identified by the 1st eigen value associated with each BS RU antenna port projected on the corresponding to the basis vectors which are known to the DU and RU (forming the beam spatial domain or frequency domain). A person of ordinary skill in the art before the effective filing date of the claimed invention would have understood that the additional steps of subsequently applying a Fourier Transform to the frequency-dependent BFWs expressed as 1st eigen value of each BS/RU port and obtain the 1-tap before sending a more optimal set of coefficients to a digital beamforming unit, as taught in Maruta, could be added to the calculation of the optimum precoder matrix P2 in Nammi to achieve further compression of the beamforming coefficients as taught in Nammi because the Fourier mathematical transformation in Maruta applies to the same 1st eigen value (the obtained BFWs of the optimal precoder) taught in Nammi. Finally, the combination achieves the predictable result of reducing the bandwidth for transmitting the BFWs over the fronthaul interface between the BBU and the RU, as required and achieved through BFWs selection and quantization in Nammi, with avoiding the need of a digital singular value decomposition (SVD) precoder for the 1st eigenmode weight vectors at the RU when “SVD requires complex matrix calculation” as taught by Maruta – See § III, p.7, col1.
Therefore, Amended Claims 1 and 15 are obvious over Nammi in view of Maruta.
Regarding Amended Claims 2 and 16, dependent from Claims 1 and 15, respectively, Nammi further teaches the method according to claim 1 and the base band unit of Claim 15, wherein the sending to the RU, further comprises:
information identifying the selected one or more tap-domain BFWs, which information identifying the selected one or more tap-domain BFWs further assist the RU to perform beamforming for the communication between the UE and the base station (“the basis vectors as DFT vectors which are known to the DU and RU” – See [¶0058] but “[t]he selection of the set S and the quantization can be decided by the baseband unit” – See [¶0050] that “then decides to send a subset S of the basis coefficients and the basis vector index . . . {Vk:kϵ[l, 2, ... P]}” where S is “any subset of the set {1, 2, ... L}” so that the “remote radio unit can then reconstruct the beamforming matrix using” the coefficients, the indexed basis vectors Vk selected and S – See [¶0049]).
Maruta inherently teaches information identifying the selected one or more tap-domain BFWs because its method is based on the “large level gap between the 1st and 2nd eigenvalues . . . exploiting massive element numbers with Line-of-Sight (LoS) dominant channels” – See § I, p.1, col2, “focusing on multiuser massive MIMO which allocates only 1st eigenmode to each UE” whereby “only 1 signal stream per SA is allocated to each UE via 1st eigenmode” – See § I, p.2, col1.
Therefore, Amended Claims 2 and 16 are obvious over Nammi in view of Maruta.
Regarding Claims 3 and 17, as amended, dependent from Amended Claims 1 and 15, respectively, Nammi further teaches the method according to claim 1 and the BBU according to Claim 15, wherein the number of BFWs transmitted to the RU is reduced (after “determining a group of beamforming coefficients for a stream of data, wherein the group of beamforming coefficients comprises respective subgroups of beamforming coefficients that correspond to respective basis vectors,”– See [¶0074] e.g. for 8 frequency-domain (FD) basis vectors as in Equation 7, “each P2k can be expresses as a linear combination of the 8 basis vectors” and “the DU can compress the coefficients α and θ for each P2k,” i.e., the BFWs for the one UE transmission precoder, and “further compress the signalling between the DU and RU by choosing only 'M' values of α and θ for each P2k” – See [¶0060], e.g., choosing only M < 8 dominant eigen values from “the dominant Eigenvector of ψk” calculated using “the covariance matrix of the MIMO channel H” between 8 antennae/ports base station and the one UE – See [¶¶0056-57] and Equation 6).
Maruta further teaches the tap-domain BFWs of the selected one or more tap-domain BFWs, is selected based on a trade-off between: being large enough to comprise significant tap-domain BFWs, and being low enough to save fronthaul capacity (e.g., when only the 1st eigenvalue of the dominant Eigenvector is chosen, as in Maruta, i.e., M=1 in Nammi, there is only 1-tap BFW for each subcarrier/subband selected per UE whereby “the 1-tap TDBF weight can be applied to all frequency components” – See § I, p.3, col2 and the “1st eigenvalue usage is outstandingly effective since its transmission/reception beams are much more stable than those for 2nd and higher order eigenmodes” –See § I, p.3, col1, i.e., the corresponding “1-tap TDBF achieves comparable beamforming performance” while the “[p]hase components for TDBF are relatively aligned to that of the reference antenna element” – See § III, p.6, col1; furthermore, because only one tap is selected to be sent to the RU, the selection is low enough to save fronthaul capacity).
Therefore, Claims 3 and 17, as amended, are obvious over Nammi in view of Maruta.
Regarding Claims 4 and 18, as amended, dependent from Amended Claims 1 and 15, respectively, Nammi in view of Maruta further teaches the method according to claim 1 and the BBU according to Claim 15, wherein the selected one or more tap-domain BFWs are selected to comprise tap-domain BFWs with one or more largest magnitude (a person of ordinary skills in the art would appreciate that the dominant eigenvalue of a signal's autocorrelation matrix corresponds to the most prominent frequency component (or strongest energy) in the signal,12 when taking only the 1st eigenvalue in the dominant Eigenvector ψk calculated using “the covariance matrix of the MIMO channel H” between 8 antennae/ports base station and the UE – See Nammi:[¶¶0056-57] and Equation 6 and applying to it the Fourier Transform taught in Maruta the result will be 1-tap localized peak at the frequency associated with the dominant eigenvalue, i.e., the largest magnitude tap – See §III,p.5, col1 (“Fourier transformation of the constant weight in the frequency domain yields an impulse shaped tap coefficient in the time domain”)).
Therefore, Claims 4 and 18, as amended are obvious over Nammi in view of Maruta.
Regarding Claims 5 and 19, as amended, dependent from Amended Claims 1 and 15, respectively, Nammi further teaches the method according to claim 1 and the BBU according to Claim 15, wherein the subset of subcarriers comprises subcarriers for which respective estimated channel data is available (“a distributed baseband unit device can determine the best precoder matrix from the estimated channel from the uplink. Once it determines the channel it will find the coefficients for the linear combination of the basis vectors which are known at the distributed baseband unit as well as at the remote radio unit” – See [¶0017], whereby “channel knowledge is available at the transmitter . . . using a sounding reference signal or other means” – See [¶0053], wherein SRS are sent by the UE either wideband or in frequency hopping mode for the base station to estimate channel quality for MIMO precoding and beamforming; furthermore, the channel matrix H is used to create “a partial covariance matrix of the MIMO channel H” used to derive “the optimum precoder P2k for the kth CSI-RS port” of each of the P ports – See [¶¶0056-57] i.e., the BFWs are calculated for a subset of subcarriers for which respective estimated channel data is available at the base unit).
Therefore, Claims 5 and 19, as amended, are obvious over Nammi in view of Maruta.
Regarding Amended Claims 6, Nammi further teaches a computer program product comprising a computer program comprising instructions, which when executed by a processor, causes the processor to perform actions according to one of the claim l (as shown in Fig. 10, “computer 1000 operable to execute the functions and operations performed in the described example embodiments” e.g., the actions in Fig. 8 – See [¶0089] wherein “program modules include routines, programs, components, data structures, etc., that perform particular tasks or implement particular abstract data types” – See [¶0090]). In addition, the mathematical transformations taught in Nammi in view of Maruta and in Ahmed are standard libraries in various computer libraries.
Therefore, Amended Claims 6 is obvious over Nammi in view of Maruta.
In sum, Claims 1-6, and 15-19, as amended, are rejected under 35 U.S.C. §103 as obvious over Nammi in view of Maruta.
Claims 8-10, 13, and 25, as amended, are rejected under 35 U.S.C. 103 as being unpatentable over Nammi in view of Maruta as applied to Amended claim 1 above, and further in view of Ahmed et al., Overhead Reduction of NR type II CSI for NR Release 16," WSA 2019; 23rd International ITG Workshop on Smart Antennas, Vienna, Austria, 2019, pp. 1-5, (hereinafter Ahmed).
Regarding Amended Claim 8, Nammi teaches a method performed by a Radio Unit, RU, for performing beamforming for a communication between a User Equipment, UE, and a base station in a wireless communications network using a multiple antenna system for communication, wherein the RU is associated with the base station (“Once the baseband unit sends the beamforming coefficients to the remote radio unit, the remote radio unit can perform digital beamforming 322, IFFT/CP addition 324, Digital to analog conversion 326, and then perform analog beamforming 328 before transmitting the data to the UE” – See [¶0043] and Fig. 3, whereby “[d]uring beamforming, a data stream can be used to generate multiple data streams, each corresponding to an antenna port, and the data streams can each be modified based on a beamforming vector” – See [¶0038]), the method comprising:
receiving over a fronthaul interface from a Base Band Unit, BBU, associated with the base station (the “DU 204, and RU 206 can be linked via a fiber optical network or other high bandwidth front haul network” and “the transmissions sent between . . . can be digital” – See [¶0035]),
one or more tap-domain BFWs selected by the BBU (“the remote radio unit receives . . . the beamforming coefficients” from the DU over the fronthaul link – See [¶0046] and Fig. 4, whereby and “each [precoder vector] P2k can be expressed as a linear combination of the basis vectors,” e.g., basis vectors in frequency domain (FD) and “ further compress the signalling between the DU and RU by choosing only 'M' values of αk,l for each P2k” – See [¶0060] e.g., select “beamforming coefficients with a highest spectral efficiency of the portions of the subgroups of the beamforming coefficients” – See [¶0064], i.e., select the dominant eigenvalues of the MIMO channel autocorrelation matrix H, e.g., a “selection component 506 can be included that is configured to compute spectral efficiencies associated with portions of the subgroups of beamforming coefficients” and select “beamforming coefficients with a highest spectral efficiency” – See [¶0069] then “the selection component 506 can ignore [small] coefficient and only send the larger coefficients . . . based on the available throughput and/or need for compression” or “number of coefficients selected can be inversely proportional to the number of layers or antenna ports” – See [¶0070]; finally, the “baseband unit then decides to send a subset S of the basis coefficients and the basis vector index” to the RU – See [¶0049]; because “the basis vector/matrix that is known to both the DU and the RU” – See [¶0051] is based on DFT vectors, the BFWs may be phase/amplitude coefficients of frequency-domain (FD) components, therefore prone to applying the Fourier transform to obtain the largest 1-tap TDBF, as taught in Maruta, which “the baseband unit quantizes and sends” together with one basis vector index to the RU),
reconstructing tap-domain BFWs based on the selected one or more tap-domain BFWs (following an equation similar to Equation 2 of Nammi, remote radio unit can then reconstruct the 1-tap BFW from the selected and quantized BFW from the BBU – See [¶0049] and for the 1-tap TDBF method the RU would know that there is only one tap to be reconstructed; see also Ahmed infra teaching quantization of BFWs),
transforming by a mathematical transformation, at least some of the reconstructed tap-domain BFWs of the one or more tap-domainBFWs related to respective subcarriers out of a number of subcarriers (use the inverse Fourier Transform on the reconstructed 1-tap BFW to obtain the 1st eigenvalue for each subcarrier where the dominant Eigenvector of ψk was calculated for one UE/layer, whereby all other BFWs are zero to preserve the dimensionality of the dominant eigenvectors precoder matrix), and
performing beamforming with the obtained frequency domain BFWs on the respective subcarriers out of the number of subcarriers for the communication between the UE and the base station (“the digital beamforming 414 is performed at the remote radio unit” whereby “digital beamforming block uses the beamforming coefficients along with a basis vector matrix to perform the beamforming on each kth data stream corresponding to P antenna ports”– See [¶0046] and Fig. 4, i.e., in either the beam-space domain or the frequency-domain, depending on the basis vectors, “for each antenna port P there is a set of beamforming coefficients α and θ that are used, in conjunction with the corresponding basis vector, to digitally beamform the data stream that corresponds to the port” or “the modifiers that weight the already known V” basis vectors known between the DU and the RU – See [¶0051]).
Nammi teaches choosing “the best M from 8 basis vectors” – See [¶0061] (which are “essentially DFT vectors” that can be used in frequency-domain and “can also be seen as a basis vectors of the beam-space” – See [¶0059]), whereby “combinations are tested by the baseband unit/DU” to “define precodersmall as the V of per port SVD,” i.e., a subset of M – See [¶0062] e.g., choose the subset of BFWs that “gives the best M metric values or spectral efficiency or predicted SINR,” i.e., M may be smaller than 8, and the RU can then “construct the precoder vector from the chosen alphas and the basis vectors” – See [¶0062] and notes that “[a]s the M decreases, the spectral efficiency decreases, but only slightly, and approaches no difference as the SNR increases,” – See [¶0066] and Fig. 6, therefore, using the 1st eigenvalue and one basis vector (M=1) would yield sufficient beamforming gain, as taught in Maruta – See §I, p.3, col1 (“1st eigenvalue usage is outstandingly effective since its transmission/reception beams are much more stable than those for 2nd and higher order eigenmodes”). Although applying an inverse Fourier Transform to the selected tap-domain BFW(s) to obtain the original 1st eigenvalue is obvious for one of ordinary skills in the art, Nammi in view of Maruta does not teach using more than the one eigenvalue for the tap-domain transformation.
Ahmed teaches methods for overhead reduction in “new radio (NR), massive MIMO” wireless systems where “the gNodeB (gNB) can build the downlink (DL) precoding scheme” – See §I, p.1, col1. Ahmed, like Nammi:[¶0058], teaches a “collection of vectors can be used to approximate the eigenvectors of the channel covariance matrix by means of suitable weighted linear combinations” and calculate the optimal precoder W2 per subcarrier/subband – See §II, p.2, col1, which can be done, e.g., by using Equation 1 or Equation 2 in Nammi, wherein the corresponding α and θ coefficients/weights applied to the basis vector/matrix that is known to both the DU and the RU and would correspond to each “FD component amplitude and phase coefficients” of the M number of frequency domain (FD) basis vectors– See §III (C), p.3, col1 and Fig. 6. By representing the spectral density inside the precoder using frequency-domain basis vectors for one UE, as shown in Fig. 3, it is noted that “more energy is concentrated in the left part of the matrix” and “a bit-map matrix [can be used] to indicate the locations of the significant elements,” and “[t]herefore, it makes sense that only the most significant K0 FD coefficients,” i.e., the best BFWs and basis vectors, be used – See §II (A), p.2, col2. Just like Maruta, Ahmed notes that “[i]nside the matrix of eigenvectors W2, there will be a phase ambiguity factor from one column (subband) to the other” and “propose to pre-normalize the phase information of each subband eigenvector (column), by taking the phase information of the strongest spatial beam on the same subband as a reference such that the phase information of the strongest spatial beam is zero for all subbands after phase pre-normalization” – See §II (B), p.3, col1-2; accord Maruta, §III, p.5,col1 (“in-band phase fluctuation is not so huge whereas the individual phase information fluctuates largely with bandwidth” whereby “the beamforming weight is determined by the relative CSI instead of absolute CSI; common phase offset for all elements is not important” and “[t]he stable relative phase information enables us to apply the same beamforming weight for all frequency components” i.e., 1 subcarrier or n continuous subcarriers of a channel, and apply the “Fourier transformation of the constant weight in the frequency domain”).
Ahmed further teaches using more than one basis vector and eigenvalue(s) for the optimal precoder (as shown in Fig. 4, by “looking at the statistics of amplitude of the FD coefficients . . . FD0 component is the strongest and the second strongest is half the amplitude of the strongest one on average . . .not surprising considering the properties of DFT-based signal compression” because in the frequency-domain BFWs, “Fourier-based compression of a correlated signal tend to focus the signal energy in the low-pass components,”– See §III (C), p.3, col2, e.g., the largest eigenvalue is observed on the first basis vector wherein “the strongest frequency component inside Wf [the basis matrix] is typically the DC component, as explained in section III-C” – See §III (D), p.4, col1 and Fig. 6, showing the beam space projected on the M FD basis vectors and the coding of the FD BFWs; in addition, “The strongest beam is more frequency flat than other beams,” i.e., “very close to ‘1’ across all subbands” and “in addition after phase pre-normalization, the strongest beam has zero phase information” so it is more efficient/higher information density achieved “to select FD components on other spatial beams and to approximate the strongest beam in W2 by an all ′1′ vector” – See §III (B), p.3, col2, i.e., transmit the other eigenvalues of the dominant Eigen vector for each subcarrier/subband). Thus, Ahmed teaches that what matters is the bitmap of the other BFWs/eigenvalues because the 1st eigen value, i.e., the main subcarrier is always present in the precoder, hence overhead can be reduced, and a “similar idea was also used in [7], to reduce the tap selection overhead in time domain explicit CSI feedback” – See id., citing Ahmed et al., "Comparison of Explicit CSI Feedback Schemes for 5G New Radio," 2019 IEEE 89th Vehicular Technology Conference (VTC2019-Spring), and, like Nammi in view of Maruta, further teaches the tradeoff between the number of selected basis vectors (in frequency or tap domain) and the overhead of transmitting the optimum precoder (“assigning a higher number of quantization bits for the first FD component Na1 and Np1, as described in section III-C, results in a better performance overhead trade-off compared to the baseline case when Na1 = Na and Np1 = Np,” i.e., when all basis vector BFWs are assigned the same number of bits in which case a lot of coefficients would be zero – See §V, p.4, col2; therefore, a person of ordinary skills in the art would learn that choosing the quantization step is a tradeoff between precision of the precoder/beam strength needed to achieve a certain transmission throughput with the UE and the overhead of transmitting its coefficients over the fronthaul to the transmitting RU – See, e.g., Fig. 7 showing such tradeoff).
Thus, Nammi in view of Maruta and Ahmed each describes beamforming techniques in a MIMO system using precoding matrices containing beamforming coefficients/weights (BFWs) corresponding to a DFT basis matrix in frequency domain (FD) wherein the first FD component, mapped to the central frequency of each subband/set of subcarriers has the largest magnitude (the 1st eigenvalue). A person of ordinary skill in the art before the effective filing date of the claimed invention would have understood that the step of applying the Fourier Transformation to the 1st eigenmode vector in Maruta could be applied to a matrix of dominant Eigen vectors such as ψk calculated in Nammi for each port P and each selected subcarrier/subband, whereby the 1st eigenvalue is approximately constant across selected subbbands/subcarriers and would be coded on more bits and transmitted as such, as taught in Ahmed, while the rest of eigenvalues for each FD basic vector would be coded on the same (fewer) amount of bits, as also taught in Ahmed, because the transformation to the tap-domain BFWs in Maruta is a routine mathematical transformation, e.g., from the class of Discrete Cosine Transforms (DCT) 13, whereby a Fast Fourier Transform could be applied to a complex matrix of phase/amplitude coefficients (BFWs) corresponding to each FD basis vector with non-null eigenvalues (depending on the precoder precision needed to achieve a certain transmission rate/throughput) while a DCT would be applied to two matrices, one for phase and one for amplitude but suffers from loss of coherence between the two when it comes to exact inverse reconstruction. Finally, the combination achieves the predictable result of precisely quantifying the tradeoff between the bandwidth for transmitting the BFWs over the fronthaul interface between a BBU and an RU by using the method taught in Ahmed combined with the transformation of FD BFWs to a sparser space such as the tap-domain, as taught in Maruta.
Therefore, Amended Claim 8 is obvious over Nammi in view of Maruta and further in view of Ahmed.
Regarding Amended Claim 9, dependent from Amended Claim 8, Nammi in view of Maruta further teaches the method according to claim 8, wherein the receiving from the BBU, further comprises:
receiving information identifying the selected one tap-domain BFW (“the optimum precoder P2k for the kth CSI-RS port is given by the dominant Eigenvector of ψk” for one subcarrier set/subband use for transmission – See [¶0057] and each P2k precoder can be decomposed on “the basis vectors as DFT vectors which are known to the DU and RU” – See Nammi:[¶0058] and Equation 7, while preserving the relationship with the beam-space domain as shown in Equation 8; then, a smaller number of basis vectors, M, may “define precodersmall as the V of per port SVD” – See Nammi:[¶0062] after a “selection component 506 can be included that is configured to compute spectral efficiencies associated with portions of the subgroups of beamforming coefficients” and “select a portion of the subgroups of beamforming coefficients with a highest spectral efficiency of the portions of the subgroups of the beamforming coefficients to add to a reduced size group of beamforming coefficients” – See Nammi:[¶0069] and “The baseband unit then decides to send a subset S of the basis coefficients and the basis vector index,” e.g., which of the basis vectors 1. . .M are used – See [¶0049]; Maruta further teaches that the “1st eigenmode transmission, which is equal to maximal ratio transmission (MRT) . . . is performed for each subcarrier” and that the 1-tap FDBF obtained by applying the Fourier Transform to the 1st eigenvalue “achieves comparable beamforming performance; the difference is only about 1 dB” – See § III, p.6, col1 and Fig. 3(a), therefore M=1 is indicated and the selected 1-tap of the complex eigenvalue is transmitted; in addition, Nammi teaches that the “DU and RU . . . send indices in the codebook to determine which column to look at and a multiplier for each column” – See [¶0046] whereby the codebook contains BFWs which can be projected on various DFT -based basis vectors in space, frequency or tap domains)
Ahmed further teaches receiving information identifying the selected one or more tap-domain BFW (in the precoder W2 matrix, comprising “the columns (dominant eigenvectors),” which is the same as the optimal precoder in Nammi, to “pre-normalize the phase information of each subband eigenvector (column), by taking the phase information of the strongest spatial beam on the same subband as a reference such that the phase information of the strongest spatial beam is zero for all subbands after phase pre-normalization” and, in addition “the strongest spatial beam is very close to [being present] across all subbands,” therefore focusing on “FD components on other spatial beams” for the FD coefficients amplitude and phase – See §III(B), p.3, col1-2, while the first FD component is the center frequency/subcarrier of each subband and its BFWs are “going to survive the selection process” – See §III(D), p.4, col1 and Fig. 6, like in Maruta, where the 1st eigenvalue associated with the FD basis vectors is selected. Ahmed, like Nammi, further teaches determining the strongest FD coefficients inside the precoder matrix, i.e., higher order eigenvalues per FD component – See, e.g., Figs. 2 and 3, and a “bitmap is built indicating the locations of . . . the number of non-zero FD coefficients K1” – See §III(B), p.3, col1, e.g., how many eigenvalues to consider in each subband eigenvector (column) of the precoder. From here, a person of ordinary skills in the art could apply the TDBF method using a Fourier transform taught in Maruta to each of those non-zero values in each eigenvector based on the indication and selecting only the 1-tap per transformed amplitude/phase eigenvalue of a subcarrier/subband, because “1-tap TDBF achieves comparable beamforming performance” as taught in Maruta supra, and no additional indication beside that taught by Ahmed and/or Nammi is necessary).
Therefore, Amended Claim 9 is obvious over Nammi in view of Maruta and further in view of Ahmed.
Regarding Amended Claim 10, dependent from Amended Claim [[8]]9, Ahmed further teaches the method according to claim [[8]]9, wherein the reconstructing of the tap-domain BFWs of the selected one or more tap-domain BFWs further comprises any one or more out of:
filling zeros at the positions of frequency domain BFWs that are unselected according to the received information identifying the selected one or more tap-domain BFWs (the precoder W2 is built so “[a]fter applying quantization, only K1<K0 among the K0 FD coefficients are non-zero” out of “the strongest K0 FD coefficients” – See §III(A), p.3, col1, i.e., a restricted number of eigenvalues per subband eigenvector (column), i.e. BFWs, will be sent to the RU for each FD basis vector, the rest will be zero and no 1-tap TDFB would be identified for them, as taught in Maruta).
Therefore, Amended Claim 10 is obvious over Nammi in view of Maruta and further in view of Ahmed.
Regarding Amended Claim 13, Nammi further teaches a computer program product comprising a computer program comprising instructions, which when executed by a processor, causes the processor to perform actions according to one of the claim 8 (as shown in Fig. 10, “computer 1000 operable to execute the functions and operations performed in the described example embodiments” e.g., the actions in Fig. 8 – See [¶0089] wherein “program modules include routines, programs, components, data structures, etc., that perform particular tasks or implement particular abstract data types” – See [¶0090]). In addition, the mathematical transformations taught in Nammi in view of Maruta and in Ahmed are standard libraries in various computer libraries.
Therefore, Amended Claim 13 is obvious over Nammi in view of Maruta and further in view of Ahmed.
Regarding Amended Claim 25, dependent from Amended Claim 9, Nammi further teaches the method according to claim 9, wherein the reconstructing the tap-domain BFWs is based on the information identifying the selected one or more tap-domain BFWs (“the baseband unit quantizes and sends {k, αk^, θ k^; kϵS}” which are approximations of “the basis coefficients and the basis vector index” where “S can be {1, 2, 5} or any subset of the set {1, 2, ... L}” layers or UEs/data streams, and the “remote radio unit can then reconstruct the beamforming matrix using the following” as a liner combination of S complex BFWs – See [¶0049] and Equation 2; therefore the reconstruction from the transmitted transformed/quantized BFWs uses (1) the subset S, (2) the basis vectors, be them in the FD, the TD or the SD, and (3) index M of the basis vectors with non-zero BFWs, i.e., the selected BFWs; all of (1)-(3) are taught by Nammi as explained in Amended Claim 9, supra; in addition, Maruta specifically teaches the 1-tap transformation before quantization, as explained in Amended Claim 8 supra).
Therefore, Amended Claim 25 is obvious over Nammi in view of Maruta and further in view of Ahmed.
In sum, Claims 8-10, 13, and 25, as amended, are rejected under 35 U.S.C. §103 as obvious over Nammi in view of Maruta and further in view of Ahmed.
Amended Claims 11-12 are rejected under 35 U.S.C. §103 as being unpatentable over Nammi in view of Maruta and Ahmed as applied to Amended Claim 8 above, and further in view of Fellhauer et al., U.S. Patent Application Publication 2020/0212984 (hereinafter Fellhauer).
Regarding Amended Claim 11, dependent from Amended Claim 8, Nammi in view of Maruta and Ahmed further teaches the method according to claim 8, further comprising
when frequency domain BFWs have not been obtained on all subcarriers14 (Maruta teaches that “channel environments in millimeter wavebands are considered to be dominated by the LoS component [directional beam] since BS and/or UEs are required to have highly directive antennas in order to obtain adequate transmission/reception performance” and “[g]iven the LoS environment, 1st eigenvalue usage is outstandingly effective since its transmission/reception beams are much more stable than those for 2nd and higher order eigenmodes” – See §I, p.3, col1; then “the first eigenmode reception weight can be approximately obtained as the simple reception weight determined for the case in which only a single antenna element located around the center of the array antenna at UE side transmits a training signal for channel estimation” – See § III, p.4, col2-p.5, col1; accord with Nammi:[¶0053] (“Where H is the precoding matrix. If the complete channel knowledge is available at the transmitter, this can then be done using a sounding reference signal or other means”); therefore, the channel precoder matrix H is approximated from the subcarrier set used for the pilot signal or for the SRS received from the UE, i.e., not for each of all subcarriers; because the BFWs in the precoder matrix P2 are calculated from the eigenvalues of the dominant Eigen vector for each port/antenna element at the BS, and the Eigen vector is obtained from the covariance matrix of the MIMO channel H – See Nammi:[¶0056-57] when “the DFT vectors which are known to the DU and RU” as “the basis vectors” are selected in the frequency domain, the corresponding BFWs, e.g., amplitude and phase, are not obtained for all subcarriers – See Nammi:[¶0058] and Equation 7; Ahmed further teaches how to obtain FD BFWs from a (SD “grid-of-beams”) matrix of eigenvectors, whereby the “collection of vectors can be used to approximate the eigenvectors of the channel covariance matrix by means of suitable weighted linear combinations . . . in in the spatial domain (SD), hence the resulting 2L beams are also referred to as SD components” and building “a subband matrix W2,” i.e., the precoder, from “the l strongest eigenvectors of the channel covariance matrix” – See § II, p.2, col1, using “a frequency compression matrix of size N3 ×M” wherein N3 is the number of subbands and M is “the number of frequency domain (FD) basis vectors” – See § III, p.2, col2; these operations mirror Nammi’s method for the case of one subband and the selected M basis vectors based on BFWs that concentrate the most of spectral efficiency; Ahmed further teaches that the FD components, i.e., the basis vectors in frequency domain, are weighted by BFWs representing amplitude and phase “[i]nside the matrix of eigenvectors W2” wherein “one column (subband)” contains the strongest eigenvectors – See §III (B), p.3, col1, and the strongest FD component in a subband, i.e., the one with the largest amplitude/BFW, is “typically the DC component” of the subband, i.e., the central frequency/subcarrier in the subband – See § III(D), p.4, col.1 and Fig. 4; therefore when applying the 1st eigenvalue/1-tap method in Maruta, only the DC component is properly beamformed).
Although Ahmed further teaches that “frequency domain interpolation is applied to estimate information for the W2 missing . . . subbands” – See § V, p.4, col2, Nammi in view of Maruta and Ahmed does not teach how to obtain the frequency domain BFWs on the remaining subcarriers out of the number of subcarriers based on the transformed frequency domain BFWs
Fellhauer teaches device and method for “determin[ing] a reduced set of transmit beamforming information . . . , wherein said reduced set comprises beamforming information for a reduced set of subcarriers in the frequency domain or for a reduced set of taps in the time domain, wherein the subcarriers of said reduced set or the taps of said reduced set are determined based on an error criterion” – See [¶0010], i.e., another metric for determining the best M basis vectors beside the spectral efficiency and similar to predicted SINR taught in Nammi:[¶0063].
Fellhauer further teaches BFWs reconstruction at a T-RU (“the transmitter has to reconstruct the beamforming matrices in order to apply them on the transmit signals first. The outcome of this reconstruction process is a beamforming matrix for each subcarrier depicted as ~V” – See [¶0046], including a method of “averaging beamforming matrices of multiple adjacent subcarriers and feedback of the resulting averaged matrix supplemented by the used group width,” e,g., as used in “current standard IEEE 802.11ac” which “does not specify the method to be used for combining multiple adjacent V-matrices” – See [¶0047]).
Fellhauer further teaches when frequency domain BFWs has not been obtained on all subcarriers (“include only specific transmit beamforming information (e.g. beamforming matrices), also called a reduced set of transmit beamforming information, . . . (so-called support vectors) and skip entries that do not exceed a certain error threshold if skipped. Said error threshold represents an error criterion used according to the present disclosure to select for which subcarriers or taps feedback information shall be included ” – See [¶0049], e.g., “When observing the characteristics of transmit beamforming matrices . . . many of the resulting numeric values (Givens angles) evolve linearly over frequency/subcarrier indices” therefore “[a]fter applying Givens-decomposition on these matrices, each matrix can be represented by I . . . real-valued angles” whereby each value is “treated as multiple discrete functions fi[k] (with i=l ... I) depending on the subcarrier index k” and “the function index I can reflect the entries of a V-matrix directly or respective angles after transformation using Givens-Rotation/Gauss-Jordan-Decomposition or other compression methods that treat V for each subcarrier independently” – See [¶0052]; then “a vector of support positions in time/frequency domain sapp ⸦Ssub with length J is defined containing a reduced number of all available positions Ssub={0, 1,... Nsub-l}” and “[e]ach entry of sapp then indicates positions for each of the I functions that should be included in the reduced feedback” – See [¶0046]).
Fellhauer further teaches that “Fig. 10 particularly shows a schematic diagram of a device to reconstruct fi,approx by using a bank of reconstructors for fixed group width” as “a component of a reconstruction unit 43 depicted in FIG. 4” – See [¶0056], wherein “[i]n between these support positions different methods of interpolation or approximation to derive fi,approx can be applied” e.g., using segment-wise linear interpolation and support vector sapp[j]– See [¶0055] and thereafter obtaining the real-valued angles I functions and performing the inverse transformation V-1 to obtain BFW for each independent subcarrier).
Thus, Fellhauer and Nammi in view of Maruta and Ahmed each teaches methods to compress feedback when transmitting BFWs of a precoder matrix, including calculating BFWs only on a subset of channel subcarriers. A person of ordinary skill in the art before the effective filing date of the claimed invention would have understood that the method of obtaining frequency (or time) domain BFWs on the remaining subcarriers out of the number of subcarriers based on the transformed frequency domain BFWs, as taught by Fellhauer could have been used as the step of frequency domain interpolation for the missing subcarriers/subbands, as taught in Nammi in view of Maruta and Ahmed, because both serve the purpose of determining BFWs for FD components which had zero-value BFWs in the precoder matrix or subcarriers for which no channel precoder matrix H is known at the BS. Furthermore, a person of ordinary skill in the art would have been able to carry out the combination through techniques known in the art. Finally, the combination achieves the predictable result reducing the set of transmit beamforming information, as taught in Nammi in view of Maruta and Ahmed, while selecting subcarriers or taps feedback information for those subcarriers or taps that minimize an error criterion.
Therefore, Amended Claim 11 is obvious over Nammi in view of Maruta and Ahmed, and further in view of Fellhauer.
Regarding Amended Claim 12, dependent from Amended Claim 11, Fellhauer further teaches the method according to claim 11, wherein the obtaining of the frequency domain BFWs on the remaining subcarriers out of the number of subcarriers based on the transformed frequency domain BFWs, is performed by any one or more out of:
(i) repeating the corresponding frequency domain BFWs on neighboring sub carriers (e.g., when “averaging beamforming matrices of multiple adjacent subcarriers and feedback of the resulting averaged matrix supplemented by the used group width” – See [¶0047], the frequency domain BFWs corresponding to the average per group would be repeated on each subcarrier in the group)
(ii) interpolating the corresponding frequency domain BFWs (“In between these support positions different methods of interpolation or approximation to derive f i,approx can be applied” – See [¶0055])
(iii) combining (i) and (ii) by partial interpolation and then repeating on neighboring sub carriers.
Therefore, Amended Claim 12 is obvious over Nammi in view of Maruta and Ahmed, and further in view of Fellhauer.
In sum, Amended Claims 11-12 are rejected under 35 U.S.C. §103 as obvious over Nammi in view of Maruta and Ahmed, and further in view of Fellhauer.
Conclusion
The prior art made of record and not relied upon is considered pertinent to applicant's disclosure:
Brown et al., U.S. Patent Application Publication No. 2022/0255606 as used in the previous Office Action;
Hindy et al., U.S. Patent Application Publication No. 2022/0094405 discloses a SD basis matrix wherein are projected restricted beams (beams with zero amplitude) and unrestricted beams (beams with unit amplitude) using IFFT performed on the beam weights and taps can be output;
Estella Aguerri et al., U.S. Patent Application Publication No. 2020/0137835 discloses subband compression when antenna receiver includes an RRU and a BBU communicating between themselves through a fronthaul (FH) link;
Chopra et al., U.S. Patent Application Publication No. 2020/0044711 discloses the BBU in Nammi in more detail;
Mittal et al., U.S. Patent Application Publication No. 2023/0122199 teaches a codebook subset restriction configuration including a set of restricted beams where set of coefficients can be generated by transforming a set of beam weights from a frequency domain to a time domain;
Ko et al., U.S. Patent Application Publication No. 2013/0022143 teaches MIMO beamforming method and apparatus;
Kuriyama et al., U.S. Patent Application Publication No. 2022/0209830 teaches filter tap calculation of tap coefficients for the time-domain linear equalization unit by representing the estimated transfer function matrix as a matrix polynomial, taking an inverse response of the matrix polynomial as a transmit weight matrix, and approximating the transmit weight matrix with Neumann series;
Barbieri et al., U.S. Patent Application Publication No. 2024/0356789 teaches O-RAN management framework including control of beamforming information;
Xia et al., U.S. Patent Application Publication No. 2009/0233556 teaches analog beamforming coefficients includes selecting a signal tap from a multi-tap wireless channel for beamforming communication;
O-RAN Alliance, O-RAN Fronthaul Working Group, O-RAN.WG4.CUS.0-v05.00, “Control, User and Synchronization Plane Specification,” published February 2021;
3GPP TS 38.211 V16.5.0 (2021-03), “Technical Specification Group Radio Access Network; NR; Physical channels and modulation (Release 16)”;
3GPP TR 38.901 V16.1.0 (2019-12), “Technical Specification Group Radio Access Network; Study on channel model for frequencies from 0.5 to 100 GHz (Release 16)” 7.7.2 Tapped Delay Line (TDL) models;
3GPP TR 25.814 V7.1.0 (2006-09), “Technical Specification Group Radio Access Network; Physical layer aspects for evolved Universal Terrestrial Radio Access (UTRA) (Release 7)” teaching the multi-antenna channel model is a tapped delay line model with covariance matrices for describing the fast-fading correlation and power distribution over transmit and receive antennae;
3GPP TR 38.801 V14.0.0 (2017-03), “Technical Specification Group Radio Access Network; Study on new radio access technology: Radio access architecture and interfaces (Release 14)”;
3GPP TSG-RAN WG1 Meeting #95, R1-1813883, Title: “WF on Type II overhead reduction”, Source: Ericsson et al., November 2018, disclosing FD and SD compression;
3GPP TSG RAN WG1 Meeting #94bis, R1-18111526, Title: “On fast SRS precoder updation,” Source: CEWiT, October 2018;
Darsena et al., “Beamforming and Precoding Techniques,” published in “Wiley 5G Ref: The Essential 5G reference Online” First published: 30 October 2019, Online ISBN: 9781119471509| DOI: 10.1002/9781119471509 (hereinafter Darsena)
Osman et al., “Performance Evaluation of a Low-Complexity OFDM UMTS-LTE System,” VTC Spring 2008 - IEEE Vehicular Technology Conference, Marina Bay, Singapore, 2008, pp. 2142-2146, doi: 10.1109/VETECS.2008.479;
Idres et al., “Identification of Taps in Time-Variant Multipath Channels for 3GPP LTE-Downlink,” European Wireless 2015, p. 306-311, ISBN 978-3-8007-3976-9, VDE VERLAG GMBH, Berlin, Offenbach, Germany;
Ning et al., “Precoding Matrix Indicator in the 5G NR Protocol: A Tutorial on 3GPP Beamforming Codebooks,” IEEE Communications Surveys & Tutorials, January, 2026;
Maruta et al., “First Eigenmode Transmission by High Efficient CSI Estimation for Multiuser Massive MIMO Using MillimeterWave Bands”; Sensors, 16(7), 1051. https://doi.org/10.3390/s16071051;
Li et al., “Hybrid beamforming designs for 5G new radio with fronthaul compression and functional splits.” IET Commun., 14: 3676-3685. https://doi.org/10.1049/iet-com.2020.0188, (2020);
Kang et al., "Fronthaul Compression and Precoding Design for C-RANs Over Ergodic Fading Channels," in IEEE Transactions on Vehicular Technology, vol. 65, no. 7, pp. 5022-5032, July 2016, doi: 10.1109/TVT.2015.2466619. keywords: {Coherence;Covariance matrices;Stochastic processes;Noise;Baseband;Downlink;Standards;Cloud-radio access networks (C-RAN);fronthaul compression;multiple-input multiple-output (MIMO);precoding;stochastic channel state information (CSI)};
Obara et al., "Joint fixed beamforming and eigenmode precoding for super high bit rate massive MIMO systems using higher frequency bands," 2014 IEEE 25th Annual International Symposium on Personal, Indoor, and Mobile Radio Communication (PIMRC), Washington, DC, USA, 2014, pp. 607-611, doi: 10.1109/PIMRC.2014.7136237. keywords: {MIMO;Throughput;Signal to noise ratio;Transmitting antennas;Transmission line matrix methods;Bit rate;5G;higher frequency bands;Massive MIMO;analog fixed beamforming;eigenmode precoding};
Ahmed et al., "Comparison of Explicit CSI Feedback Schemes for 5G New Radio," 2019 IEEE 89th Vehicular Technology Conference (VTC2019-Spring), Kuala Lumpur, Malaysia, 2019, pp. 1-5, doi: 10.1109/VTCSpring.2019.8746469. keywords: {Time-domain analysis;Principal component analysis;Precoding;MIMO communication;5G mobile communication;Transmitting antennas;Bandwidth}
Ahmed et al., "Explicit CSI Feedback Design for 5G New Radio phase II," WSA 2018; 22nd International ITG Workshop on Smart Antennas, Bochum, Germany, 2018, pp. 1-5.
Applicant's Amendment, including Arguments/Remarks, necessitated the new ground(s) of rejection presented in this Office action. Accordingly, THIS ACTION IS MADE FINAL. See MPEP § 706.07(a). Applicant is reminded of the extension of time policy as set forth in 37 CFR 1.136(a).
A shortened statutory period for reply to this final action is set to expire THREE MONTHS from the mailing date of this action. In the event a first reply is filed within TWO MONTHS of the mailing date of this final action and the advisory action is not mailed until after the end of the THREE-MONTH shortened statutory period, then the shortened statutory period will expire on the date the advisory action is mailed, and any nonprovisional extension fee (37 CFR 1.17(a)) pursuant to 37 CFR 1.136(a) will be calculated from the mailing date of the advisory action. In no event, however, will the statutory period for reply expire later than SIX MONTHS from the mailing date of this final action.
Any inquiry concerning this communication or earlier communications from the examiner should be directed to LUCIA GHEORGHE GRADINARIU whose telephone number is (571)272-1377. The examiner can normally be reached Monday-Friday 9:00am - 5:00pm EST.
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/L.G.G./ Examiner, Art Unit 2478 /JAY L VOGEL/ Primary Examiner, Art Unit 2478
1 Appendix to this Office Action.
2 See Ning et al., “Precoding Matrix Indicator in the 5G NR Protocol: A Tutorial on 3GPP Beamforming Codebooks,” IEEE Communications Surveys & Tutorials, January, 2026, Figure 15, at page 21.
3 See also 3GPP TSG-RAN WG1 Meeting #95, R1-1813883, Title: “WF on Type II overhead reduction”, Source: Ericsson et al., November 2018, disclosing FD and SD compression using orthogonal DFT vectors as basis..
4 MPEP § 2124 allows references which do not qualify as prior art because they postdate the claimed invention may be relied upon to show the level of ordinary skill in the art at or around the relevant time –See Ex parte Erlich, 22 USPQ2d 1463 (Bd. Pat. App. & Inter. 1992).
5 That is, when limiting the tap-domain channel model obtained at the BBU based on the received reference signals (SRS, DMRS) to k subcarriers, on the one hand – See ‘893 Patent, col. 13: ll.26-28 (“the channel taps may be obtained by transforming the frequency domain channel values”); and obtaining at the BBU the BFWs for each the k subcarriers, on the other hand – See Spec., 4:1-12 (“BFWs on only one subcarrier is calculated at BBU and transported to the RU” and “the received BFWs calculated on certain subcarrier will be shared over other subcarriers in the same SCG” thus “beamforming performance degradation” will result “due to the mismatch of the channel coefficients on some subcarriers and the BFWs used”).
6 The reason why Applicant disclosed such calculations, either in mathematical formulae or in plain language as steps of a procedure in other applications filed on the same subject matter and not referenced here, remains unknown.
7 A set of subcarriers may be considered for multistream transmissions to the same UE – See, e.g., Maruta et al., “First Eigenmode Transmission by High Efficient CSI Estimation for Multiuser Massive MIMO Using Millimeter Wave Bands”; Sensors, 16(7), 1051. https://doi.org/10.3390/s16071051 (hereinafter Maruta2), showing in Figure 1 and intuitive system model of decomposing a multistream transmission per UE and finding the channel matrix per subcarrier as shown in Equation (1). Here we may consider transmission using one subcarrier per one UE for simplicity. A channel has a precoder matrix H usually determined per subcarrier.
8 In the BFWs matrix, an BS antenna/port performing Tx-Rx with one UE/layer can be associated with the disclosed “one path between a UE antenna and an antenna or a beam at the base station along the subcarriers within a continuous bandwidth” – Spec., 8:26-28 and Figure 2.
9 Darsena teaches, at page 5, a “simple MIMO narrowband model, encompassing NT TX and NR RX antennas” wherein “H is the NR x NT MIMO channel matrix” for a single subcarrier and for NL “the number of layers to be transmitted . . . W is a NT x NL precoding matrix” whereby the received signal is the NR x 1 RX vector y=H*W*s, wherein “the NL x 1 vector s of complex symbols is mapped to the antenna vector x”, the NT x 1 TX vector, using linear precoding.(LP); the model “can be similarly adapted to describe both DL and UL operations.” Precoding matrix for spatial multiplexing in NR are further defined in § 6.3.1.5, 3GPP TS 38.211 V16.5.0 (2021-03), “Technical Specification Group Radio Access Network; NR; Physical channels and modulation (Release 16)” (hereinafter 3GPP TS 38.211), stating, at page 34, “For codebook-based transmission, the precoding matrix
W
is given by
W
=
1
for single-layer transmission on a single antenna port, otherwise by Tables 6.3.1.5-1 to 6.3.1.5-7”
10 See also Maruta infra stating, in §III, p.5, col1, that “when we observe relative phase information to the reference antenna element, in-band phase fluctuation is not so huge whereas the individual phase information fluctuates largely with bandwidth. The individual phase information is given by 2πdmf/c where dm is the distance between transmission/reception antennas, f is the carrier frequency and c is the light speed” and this “stable relative phase information enables us to apply the same beamforming weight for all frequency components” of the beam between
11 See Nammi:¶0051] (“for each antenna port P there is a set of beamforming coefficients α and θ that are used, in conjunction with the corresponding basis vector to digitally beamform the data stream that corresponds to the port”); those coeffi
12 Cf. Spec.,p.8:10-25, stating that both in beam-domain and frequency-domain any of a “signal, channel, BFW etc.” is “a referred quantity” associated with “each of some predefined beams” or “different frequencies,” respectively.
13 See course on Lossy Compression Algorithms in JPEG graphics based on DCT and quantization of amplitude/phase coefficients, available online at https://cs.stanford.edu/people/eroberts/courses/soco/projects/data-compression/lossy/jpeg/index.htm.
14 See also Darsena,¶3:8 (“several subcarriers belonging to a subband can be grouped and precoding is performed per-subband rather than per-subcarrier”).
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