US 9900067

I'll verify the patent details and check for any 2026 CAFC activity.

Let me look for the actual claim text and any recent appellate activity.

Let me try to retrieve the actual claim language and check for assignments / later 2026 activity.

US 9,900,067 B2 — Verification Summary

Sourcing note: I could not query the USPTO PatentCenter/Public Search API directly from this environment, and I found no CAFC 2026 docket entry for this patent. The figures below are grounded in the Google Patents record for US9900067B2 (provided as authoritative), the ETRI KSP patent record (registration no. 9900067), the EPO/PISE record, and the Stanford NPE Litigation Database. Where a detail is not independently confirmed, I flag it.

Bibliographic data

Abstract (as published)

"The present invention relates to a method and apparatus for transmitting and receiving data. A data transmission method from a sender terminal to a receiver terminal in a MIMO system using a variable frequency band according to one embodiment of the present invention comprises: repeatedly generating a signal field depending on a frequency band that is applied to the transmission of a data frame; generating a data field including the data; generating a data frame including the signal field and the data field; and transmitting the data frame to the receiver terminal. The present invention is advantageous in that a signal field which is transmitted together with the data being transmitted from the sender terminal to the receiver terminal in the MIMO system can be sent more efficiently."

Independent claims — plain language

⚠️ Uncertainty flag: The full granted claim set was not available to me (the Google Patents text I received stops before the claims, and the Family has no claim listing I could retrieve verbatim). The claim text below is taken from a third-party database reproduction of the claims of the corresponding publication US 2014/0119327 A1 for application 14/147,447. These are very likely close to the granted claims but I cannot certify they are identical to the issued text. Also note the specification's "Technical Solution" section describes a transmitter-side independent claim (iteratively generating a signal field according to frequency band; generating a data field; generating a data frame; transmitting) and a receiver-side independent claim, plus corresponding device claims — so the granted set likely contains at least one transmitter-side independent claim in addition to the receiver-side claim shown below. I could not verify that from an authoritative source.

Claim 1 — receiver-side method (WLAN):
A method in which a receiver:

• receives a first signal field over an operating band using two OFDM symbols, where the operating band's bandwidth is a multiple of 20 MHz;
• receives a second signal field over that same operating band using one OFDM symbol for a MU-MIMO transmission;
• where the second signal field contains information obtained by repeating a SIG-B a predetermined number of times according to the operating bandwidth, and that number increases as bandwidth increases;
• where the first signal field carries information common to the multiple receivers targeted by the MU-MIMO transmission, while the SIG-B carries information specific to that receiver; and
• where the second signal field is received over at least one spatial stream selected from multiple spatial streams, the selected stream(s) corresponding to that receiver.

Claim 10 — receiver-side apparatus: The device counterpart of claim 1 — a reception unit that receives the two-symbol first signal field and the one-symbol second signal field for MU-MIMO, plus a data obtaining unit that recovers data using the first and second signal fields, with the same SIG-B repetition/increasing-bandwidth, common-vs-specific information, and spatial-stream-selection limitations.

Dependent claims (2–9, 11–13) add: the first signal field is received without applying MU-MIMO; the first signal field is repeated over each 20 MHz sub-band; the fields are VHT-SIG-A and VHT-SIG-B; SIG-B is 26 bits at 20 MHz, 27 bits at 40 MHz, and 29 bits above 40 MHz; a received data field includes a CRC field used to detect errors in the second signal field; and the fields are carried as a PPDU.

Note: in the claim text above, "the first signal signal includes first information…" is an apparent typographical duplication in the source, retained rather than corrected.

Corresponding subject matter in the specification

• L-STF/L-LTF/L-SIG are legacy 802.11 fields for backward compatibility; VHT-SIG-A is the common signal field (auto-detection/compatibility, iterated per 20 MHz) and VHT-SIG-B is the dedicated per-user field.
• The core teaching is that simply repeating VHT-SIG-B like VHT-SIG-A yields an SNR gain but no frequency-diversity gain; the invention applies different interleaving per stream (or CDD with per-antenna delay) so identical coded bits land on different subcarriers of different streams.
• Worked fan-out: 20/40/80/160 MHz, 1–4 streams, non-contiguous multi-channel, one-QPSK-symbol variants, and STBC/Alamouti variants (FIGS. 11–57).
• CRC handling: because VHT-SIG-B has no spare bits at 20 MHz, 4–8 reserved bits of the service field may serve as CRC covering both the SIG-B and the scrambler seed (FIGS. 49, 54), allowing PHY/MAC shutdown on error detection to save power.
• Commercial context: ETRI's project code is 10MI3500 ("IEEE 802.11 VHT 초고속 무선랜 무선전송 연구," PI Seok-Kyu Lee), i.e., this is 802.11ac VHT signaling work.

Litigation / 2026 CAFC activity

• Asserted by Sol IP, LLC in E.D. Tex.: 2:18-cv-00526 (v. AT&T Mobility LLC), 2:18-cv-00527 (v. Sprint Corporation et al.), and 2:18-cv-00528 — all listed on the Google Patents litigation panel and the Stanford NPE Litigation Database. Also an N.D. Cal. case, 5:20-cv-00399.
• No CAFC 2026 docket entry for US 9,900,067 was found. My searches returned only unrelated 2026 Federal Circuit matters (e.g., AGI SureTrack v. Farmers Edge, Ollnova v. ecobee, Ironburg v. Valve) and unrelated 2026 PTAB/IPR items. I also found no IPR/PGR against 9900067. This is a negative result from a general web search, not a complete docket check — an appeal could exist that is not indexed in the sources I could reach.

Continuation family (for context)

US 10,374,668 B2; US 10,931,337 B2; US 11,496,187 B2; US 12,074,665 B2; and US 2024/0413862 A1, plus EP 4020830 A1 — all sharing the same title/family, consistent with ETRI's continued prosecution of this disclosure.

Overall confidence: High on title, inventors, filing/issue dates, priority chain, abstract, and litigation history. Moderate on the exact granted claim wording (relied on a publication-stage claim reproduction). Low/unverified on current ownership of record and on the absence of 2026 appellate activity.

I'll search for litigation specifically involving US 9,900,067.

Let me verify the details of these cases and search for any additional litigation.

Let me pull the Stanford NPE record and details on the other identified cases.

Litigation involving US 9,900,067

Sourcing note: I searched the Stanford NPE Litigation Database, the Unified Patents litigation portal records surfaced through Google Patents, Justia/CourtListener dockets, Ex Parte's case analytics, and IP/legal trade press. I restricted hits to the literal identifier US 9,900,067 / 9900067 and discarded near-miss identifiers that returned unrelated results (e.g., WO 99/00067 — a Univ. of Iowa neural-stimulation PCT; Indian High Court cause numbers "APSWP 9900067/2001"; a Greek procurement tender no. 9900067; a Telstra parts number 9900067). Those are not this patent.

⚠️ Date inconsistency — flagged per instructions: The task states the current date is April 26, 2026, and the system context I was given says 2026-09-19. Two of the cases below are reported as filed August 28, 2026 and are discussed in press dated September 2026 — i.e., after the April 26, 2026 "current date" in the prompt. I am not suppressing these; per the operating rule that search results are the current ground truth, I report them and treat the August/September 2026 dates as real. Treat the "current date" line in the prompt as unreliable.

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Summary table

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Case-by-case detail

1–3. The 2018 Sol IP / E.D. Tex. campaign (2:18-cv-00526 / -527 / -528).
All three were filed December 3, 2018 in the Marshall Division of E.D. Tex. before Judge Robert W. Schroeder (RWS) with Magistrate Judge Roy S. Payne (RSP). Case 2:18-cv-00526 was designated the LEAD CASE; -527 and -528 were CONSOLIDATED into it (this is stated expressly on the face of Docket No. 293). The caption in that order identifies the defendants as AT&T Mobility LLC; Cellco Partnership d/b/a Verizon Wireless; Sprint Communications Company L.P.; Sprint Solutions, Inc.; and Sprint Spectrum L.P., with Ericsson Inc. and Nokia of America Corporation as intervenors. This was a large multi-patent campaign — one docket entry notes "27 asserted patents and 497 asserted claims." The asserted patents were grouped into "LTE A," "LTE B," and "WiFi" families; US 9,900,067 is an 802.11ac/VHT Wi-Fi patent (Wi-Fi family), and Docket No. 293 shows the defendants fighting over whether the IEEE 802.11n standard could be added to their invalidity contentions against a Wi-Fi patent. The court denied that motion for leave to amend on January 7, 2020.

• Outcome: The lead case is recorded as closed on 2020-05-20. My sources do not state whether closure was by settlement, voluntary dismissal, or otherwise — I could not confirm the disposition, so I am not characterizing it as a settlement or a win for either side.
• Sources: Stanford NPE DB (https://npe.law.stanford.edu/patent/9900067); Google Patents litigation panel links (https://portal.unifiedpatents.com/litigation/Texas%20Eastern%20District%20Court/case/2%3A18-cv-00526, .../2%3A18-cv-00527, .../2%3A18-cv-00528); Docket 293 (https://law.justia.com/cases/federal/district-courts/texas/txedce/2:2018cv00526/186351/293/); status "Closed (05/20/20)" (https://ai-lab.exparte.com/case/dct/txed/2:18-cv-00526/sol-ip-llc-v-att-mobility-llc).

4. N.D. Cal. 5:20-cv-00399.
This case was surfaced on the Google Patents litigation panel for this patent. I could not confirm the defendant, the patents-in-suit, or the current status from the sources I could reach, and it did not appear in the (truncated) Stanford NPE listing I retrieved. Treat as unverified.

5–6. The 2026 Sol IP / E.D. Tex. automotive campaign (2:26-cv-00764 and 2:26-cv-00766).
Sol IP, LLC filed two suits on August 28, 2026 in E.D. Tex., both assigned to Judge James R. Gilstrap, asserting the same two patents in both cases: US 9,900,067 B2 ("Method and apparatus for transmitting and receiving data in a MIMO system") and US 10,090,894 B2 ("Method and apparatus for transceiving data in a MIMO system"). Accused technology is Wi-Fi / MIMO functionality in vehicles (802.11ac, wireless CarPlay/Android Auto, in-car hotspots). Counsel: Nelson Bumgardner Albritton and Nelson Bumgardner Conroy (Brent N. Bumgardner, John P. Murphy, Timothy E. Grochocinski, Christopher Granaghan). Both cases are recorded as Open, with no defense appearances yet at the time of the report.

• Source: https://insights.greyb.com/sol-ip-honda-volkswagen-wifi-patent-lawsuits/ (GreyB, reporting case nos. 2:26-cv-00764 and 2:26-cv-00766, filed 2026-08-28, Judge Gilstrap).
• Related context that may moot these suits: Sol IP joined Avanci's Wi-Fi 6 Vehicles pool as a licensor, and Ford/GM signed on as licensees; Chinese-language coverage of that development suggests the Honda and Volkswagen cases will likely resolve through the pool license. Source: https://ipfray.com/ford-general-motors-among-latest-licensees-to-join-avanci-wi-fi-6-vehicles-program-sol-ip-signs-up-as-licensor/.

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Negative findings

• No CAFC appeal involving US 9,900,067 was located. (Same negative result as the earlier section of this analysis; still not a complete docket check.)
• No IPR, PGR, reissue, or reexamination against US 9,900,067 was located.
• No ITC (Section 337) investigation involving this patent was located. Note the ETRI v. Shenzhen Tenda E.D. Tex. suit (2:26-cv-00398) and the ETRI Wi-Fi SEP injunction case reported in February 2026 (asserting patents such as 11,664,926; 10,313,077; 10,651,992; etc.) are different patents — I checked that '067 was not among the listed patents, so I am not including them.
• No litigation found naming ETRI itself as plaintiff on the '067 patent; all identified assertions were by Sol IP, LLC.

Who is asserting it

The Stanford NPE Litigation Database categorizes Sol IP as an "Acquired patents" asserter, and IP fray describes Sol IP as managing "a portfolio of standard-essential patents (SEPs) including many originating from South Korea's Electronics and Telecommunications Research Institute (ETRI)." This is consistent with an ETRI→Sol IP transfer/licensing arrangement rather than ETRI suing directly. The current owner of record was not confirmed from an authoritative USPTO assignment record.

Confidence: High on cases 1–3 (docket-sourced) and 5–6 (trade-press sourced). Low/unverified on case 4 and on the specific disposition of the 2018 consolidated cases. If you need certified status, pull PACER for 2:18-cv-00526 and for 2:26-cv-00764/-00766.

I'll verify the structured block's negative finding against live sources before finalizing.

Let me run two more targeted queries to be thorough on the ETRI/Sol IP family and confirm no institution denial or CBM exists.

Proceedings overview

Zero AIA trial proceedings on file for US 9,900,067. The USPTO Open Data Portal structured block reports no IPR, PGR, or CBM proceedings against US 9,900,067 as of the most recent ingest, and my independent web searches (Google Patents litigation/PTAB panels, PTAB E2E–style petition documents, and general PTAB/CAFC coverage) surfaced no petition, institution decision, FWD, or appeal naming this patent. Bottom-line defensive posture: the patent has never been tested at the PTAB — it is entirely untested and un-hardened, which means there are no canceled claims to point to and no § 315(e)(2) estoppel binding anyone. That cuts both ways: a defendant has no free kill-shot, but also faces no prior-petitioner estoppel and can be the first to attack the claims on whatever art it can find.

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No proceedings to report

• Type: N/A
• Filed: N/A
• Status: No AIA trial proceeding on file (per the canonical U.S. Open Data Portal block) — corroborated by web search.
• Judge panel: N/A
• Petition grounds: N/A
• Institution decision: N/A
• Final Written Decision: N/A — no claim of US 9,900,067 has ever been canceled, confirmed, or even challenged at the Board.
• Settlement / termination: N/A
• Appeal: No CAFC appeal from any '067 PTAB decision (there is no such decision). Note this is a negative result from general web search plus the ODP ingest, not a certified PACER/PTAB E2E docket check.
• Defensive value: The absence of PTAB activity means no petitioner has tested these claims, so the validity fight is wide open — but also unproven in your favor. The claims stand exactly as granted.

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⚠️ Critical identifier trap — do not conflate US 9,900,067 with US 9,906,067

The strongest near-miss in my searches is a different patent: US 9,906,067 (Garrity Power Services LLC, "wireless power transmission / wireless battery charging") — the subject of [Samsung Electronics Co.](/litigations/by-defendant/Samsung%20Electronics%20Co.) v. Garrity Power Services LLC, IPR2021-00389, which I found as a public petition (Paul Hastings as counsel; ground 1 based on "Kasar," U.S. Pat. No. 10,404,089). That proceeding is inapposite to your patent:

• It involves US 9,906,067 (app. no. 14/754,863, filed 2015-06-30, issued 2019-09-03, "067 patent" for wireless power), not US 9,900,067 (app. no. 14/147,447, ETRI, 802.11ac/VHT MIMO).
• Different technology, different owner, different statutory posture (AIA first-to-file), different prior art.
• I found no IPR on the ETRI '067. Any search that returns IPR2021-00389 for a query about "9900067" is a digit-transposition false positive. A defendant should confirm the patent in any demand letter is the ETRI MIMO patent before assuming the Garrity IPR history applies.

Source for the Garrity petition (shown only to identify the near-miss): https://cmosedu.com/jbaker/expert_witness/2021/IPR2021_00389.pdf.

Other false positives I discarded: Greek procurement tender 9900067 (ΔΕΔΔΗΕ); Telstra parts list no. 9900067; Univ. of Iowa–derived WO 99/00067; Rajasthan/Indian cause no. APSWP 9900067/2001; VA citation no. 9900067; and NSN 9900-067 (Woodward pump governor). None is this patent.

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Cross-check against the litigation posture (builds on the earlier sections)

Per the earlier litigation section, US 9,900,067 is being actively asserted by Sol IP, LLC (an ETRI-originated SEP/acquirer), including the 2018 E.D. Tex. campaign (2:18-cv-00526/-527/-528) and the 2026 E.D. Tex. automotive suits (2:26-cv-00764 v. Honda; 2:26-cv-00766 v. Volkswagen). The combination — years of assertion, multiple defendants, and still not a single IPR — is an unusual and telling signal:

• Defendants in the 2018 campaign (AT&T, Verizon/Cellco, Sprint, with Ericsson and Nokia intervening) evidently chose to litigate validity in district court rather than petition the PTAB. Whether that was a strategic choice, a time-bar problem, or a settlement-driven outcome, I could not confirm — the lead case closed 2020-05-20 without a stated disposition.
• The absence of any IPR on a patent asserted against multiple large carriers and now against two automakers is atypical and may indicate (a) settlements before institution was worth it, (b) the license/pool route (Sol IP joined Avanci's Wi-Fi 6 Vehicles pool) diverting challenges, or (c) a validity theory that defendants did not find PTAB-viable. I cannot verify which.

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Strategic summary

Which claims are canceled vs. sustained vs. untested. None are canceled; none are sustained. Every claim of US 9,900,067 — including at least the receiver-side independent claim and its dependents (with the transmitter-side and device claims likely present in the granted set, per the earlier summary's flagged uncertainty about the exact granted text) — is untested. There is no FWD to cite, no IPR certificate to link, and no claim you can tell a plaintiff is dead.

Estoppel landscape. Because no IPR/PGR was ever instituted against this patent, no petitioner (and no privity chain) is bound by § 315(e)(2). That means a current defendant is not blocked by anyone else's prior art grounds — but it also means there is no roadmap of "art the Board already accepted." Any prior-art challenge is a clean slate. Conversely, if you are contemplating your own IPR, note the § 315(b) one-year bar running from service of the complaint in the 2026 automotive cases (filed 2026-08-28 per the earlier section); the window to petition is running.

Pattern signals. No petitioner has filed multiple IPRs on this patent (no petitioner has filed any). There is no defensive-aggregator (Unified Patents / RPX-type) IPR in the chain that I could find — the earlier sections note Unified Patents litigation data links only, which are not petitions. The patent owner (via Sol IP) has not pursued any PTAB appeal on this patent because there has been no PTAB proceeding to appeal.

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Recommended next steps

1. Do not treat the Garrity IPR (IPR2021-00389) as relevant. If a demand letter or an opponent's invalidity narrative cites "IPR2021-00389 / the '067 IPR," verify the patent number digit-by-digit. US 9,906,067 ≠ US 9,900,067. The Garrity proceeding concerns wireless power, not 802.11ac signaling.

2. Confirm the negative with a certified docket pull. The "no PTAB activity" finding rests on (a) the canonical ODP ingest block and (b) general web search — not a PACER/PTAB E2E docket certification. Before relying on it, pull the patent's full trial-history on PTAB E2E / USPTO Patent Trial and Appeal Case Tracking System (search application 14/147,447) and the CAFC docket via CourtListener. This is the single highest-value verification step, because the whole defensive analysis turns on the absence of proceedings.

3. If you are a defendant (e.g., a 2026 Honda/VW-era target), the IPR clock is the priority. With the complaints served 2026-08-28 (per the earlier section; verify against PACER for 2:26-cv-00764/-00766), § 315(b) gives you one year from service to petition. No one has estoppel against you, and there is no institution precedent to follow — so the petition must stand on its own art. The specification's own admissions are useful targets: it repeatedly concedes that simple iteration of VHT-SIG-B like VHT-SIG-A was known and that the alleged invention is the different-interleaving-per-stream / CDD variant and the bit-allocation-by-bandwidth variant — which frames the obviousness attack.

4. If the claims survive and the patent is asserted against you, the absence of IPRs is not proof of strength. A never-challenged patent can be weak as easily as it can be strong. The realistic defenses remain (i) invalidity in district court on 802.11ac/VHT and related art, and (ii) the standard-essentiality/licensing posture, since Sol IP licenses through the Avanci Wi-Fi 6 Vehicles pool — a license may resolve the exposure more cheaply than an IPR.

5. Watch for new filings. Given the 2026 assertion activity, a first-ever IPR/PGR against this patent is plausible in the near term. If one is filed, the institution decision will arrive within ~6 months and any FWD within the 12-month statutory trial deadline from institution — milestones worth diarizing if you become a party.

Confidence: High that there is no AIA trial proceeding on US 9,900,067 as of the sources reachable here (the canonical ODP block is consistent with independent search). Moderate on completeness, because I could not run a certified PTAB E2E/PACER docket check and cannot exclude an unindexed or very recent filing. All statements about the Garrity IPR2021-00389 and the Wilus/Samsung WiFi IPRs are included only to identify them as different patents; I did not verify their outcomes and they are not asserted here to apply to the ETRI '067.

I'll research the assignment record for US 9,900,067, starting with the USPTO Assignment Center and cross-referencing NPE directories.

Let me dig into the specific assignment records and the Sol IP / ETRI transfer.

Key finding emerging. Let me verify the inventor-to-ETRI assignment record and the alleged ETRI→Sol IP transfer.

Assignment & Ownership Analysis — US 9,900,067 B2

⚠️ Sourcing limitation (read first): My research tools ran out of steps before I could pull the Assignment Center interface directly. I was not able to retrieve the reel/frame-level records for this patent (or for application 14/147,447 / PCT/KR2011/001742). I am therefore not going to invent reel/frame numbers. What follows distinguishes (a) facts I could ground in court filings, NPE directories, and the patent face, from (b) items that require a live Assignment Center pull. Where a section cannot be completed for lack of a reel/frame, I say so rather than guess.

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Inventors

• All three are named on the '067 patent with ETRI as assignee, which matches the ETRI KSP record for this registration ("Project Code 10MI3500, IEEE 802.11 VHT 초고속 무선랜 무선전송 연구," PI 이석규 / Seok-Kyu Lee). Source: https://ksp.etri.re.kr/ksp/patent/read?id=PR20100299USa.
• Unusual patterns: None found. I located no evidence of inventors leaving ETRI within 12 months of filing, no evidence of a competing spinoff, and no inventor-side assignments beyond the expected employee→institute assignment. I could not positively confirm each inventor's continued tenure (that is a personnel question, not a USPTO record), so treat "no departure" as an absence of evidence, not a verified negative.
• Note the inventors are all ETRI Daejeon; this is a normal government-research-institute inventor set — not a pattern (like the pro se / serial-inventor / address-of-convenience patterns) that usually flags a fire-sale.

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Original assignee

• Entity on the issued patent: Electronics and Telecommunications Research Institute (ETRI), 218 Gajeong-ro, Yuseong-gu, Daejeon, Republic of Korea.
• Primary line of business: ETRI is South Korea's largest government-funded electronics/telecommunications research institute (a national R&D lab, not a consumer-product manufacturer). Its output is research, standards contributions, and patent licensing.
• Did it ship a product embodying the claims? No — ETRI is a research institute. The '067 disclosure is 802.11ac "VHT" signaling work (VHT-SIG-A / VHT-SIG-B), i.e., it fed the IEEE 802.11ac standard rather than an ETRI-branded WLAN product. This matters for the NPE analysis below: the original assignee is a non-practicing research institution, which is itself an important fact.
• Current status: Operating (active as of 2026; still executing Wi-Fi SEP assertion campaigns — e.g., the reported ETRI v. Shenzhen Tenda E.D. Tex. suit 2:26-cv-00398 and the Feb-2026 ETRI Wi-Fi SEP injunction matter — on other patents).

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Assignment timeline

Bottom line: I could not complete a reel/frame-level timeline. What I can state on the record:

• The patent issued to ETRI on 2018-02-20, and Google Patents' current-assignee field still lists ETRI. On the face of the record I could reach, ETRI — not Sol IP — is the owner of record.
• The only downstream transaction I could document is not a recorded assignment at all. In IPR2020-00242 (a different ETRI patent, US 10,080,204), Sol IP stated on 2019-12-31 that "ETRI transferred to exclusive licensee Sol IP, LLC, all substantial rights … and retained no substantial rights for itself." That is a transfer-of-all-substantial-rights via exclusive license, and Sol IP filed its notices as "Exclusive Licensee," with ETRI still captioned as "Patent Owner."
• Critically, contemporaneous analysis (Mondaq, 2021-04-02, reporting on Sol IP v. Qualcomm, 6:21-cv-00270) states plainly: "Currently available USPTO assignment records do not reflect ownership by Sol IP of any US patents, including the more than two dozen asserted assets." Source: https://www.mondaq.com/unitedstates/patent/1053522/.

Consequence: For the '067 patent I have no evidence of any recorded assignment after issuance, and direct evidence that the ETRI→Sol IP relationship was structured as an unrecorded exclusive license (or a license-plus-all-substantial-rights transfer) that does not appear as a change of owner in the Assignment Center. I therefore cannot supply executed/recorded dates, reels/frames, or the recording correspondent.

Items I could NOT verify and will not fabricate:

• The original inventor→ETRI assignment reel/frame for 14/147,447 (or for parent 13/434,681 / PCT/KR2011/001742), and its correspondent of record.
• Any ETRI→Sol IP recordation (execution date, reel/frame, correspondent). Based on the Mondaq source, I do not believe one exists.
• Any change-of-name, security interest, merger, or release on this patent.

To close these three gaps, pull: https://assignmentcenter.uspto.gov/ and https://assignment.uspto.gov/patent/index.html, searching by patent number 9900067 and by application 14147447.

*(Note: generic searches did surface ETRI assignment documents with correspondents such as Paul J. Farrell / Farrell IP Law, Rabin & Berdo PC, Staas & Halsey LLP (J. Randall Reckers), and William, Park & ... — but those were all for different ETRI patents/applications. I am deliberately not attributing any of them to the '067 filing.)*

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Timeline diagram

timeline
    title Ownership of US 9900067
    2010 : Priority filings in Korea
    2011 : PCT filed by ETRI
    2014 : US continuation filed by ETRI
    2015 : Sol IP LLC formed in Virginia
    2018 : Patent issued to ETRI
         : Sol IP sues ATT Sprint Verizon
    2026 : Sol IP sues Honda and Volkswagen

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NPE / troll-pattern signals

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Verdict

NPE — high confidence.

Justification: Two strong signals are present. First, a known, repeat patent asserter controls enforcement — Sol IP, LLC, per Sol IP v. AT&T, E.D. Tex. 2:18-cv-00526/-527/-528 (filed 2018-12-03) and the 2026 E.D. Tex. 2:26-cv-00764/-00766 suits against Honda and Volkswagen, with Sol IP classified under "Acquired patents" in the Stanford NPE database. Second, the asserting entity is a licensing-only shell-style vehicle — Sol IP, LLC, a Virginia LLC formed Jan 2015 (member Choongsoo Park), holding no products and only an exclusive license with "all substantial rights" from ETRI, which it asserted in IPR2020-00242 on 2019-12-31. The original assignee, ETRI, is itself a non-practicing research institute, so there is no operating-company-asserts-competitor reading available.

Important caveat that refines (and partly corrects) the earlier sections of this analysis: the "Patent summary" section flagged a possible later assignment from ETRI to Sol IP. The stronger evidence now indicates no assignment was recorded — Mondaq reports USPTO assignment records reflect no Sol IP ownership of any US patent, and Sol IP litigates as exclusive licensee with ETRI still the owner of record. So the correct characterization is "unrecorded exclusive license / all-substantial-rights transfer," not "assignment." That distinction matters for standing and for any future ownership diligence.

Verify at: https://assignmentcenter.uspto.gov/ — search patent 9900067 and application 14147447 to obtain the exact reels/frames and correspondent that I was unable to pull here.

I'll search for the USPTO record and prior-art citations for US 9,900,067 specifically.

Let me dig into the specific citation lists for this patent.

Prior Art Analysis — US 9,900,067 B2 ("9900067")

⚠️ Headline sourcing limitation (read first)

I could not retrieve the face-of-patent "References Cited" (56) list for US 9,900,067 B2 from the sources reachable in this environment. The Google Patents text supplied to me as authoritative is truncated — it ends mid-sentence in the "MODE FOR INVENTION" section and contains no "Patent Citations" (backward) list. My four targeted searches (Google Patents citation URL, "References Cited," the application number 14/147,447, and inventor/inventor-name queries) returned mostly near-miss identifiers and unrelated documents — which I discarded per the literal-ID rule:

• Telstra part no. 9900067 (cast-iron pit crossbars) — not this patent.
• Greek procurement tender 9900067 (ΔΕΔΔΗΕ access-control purchase) — not this patent.
• NIEHS histology animal ID "HISTO: 9900067" (acrylonitrile study) — not this patent.
• Swiss/Dutch CH 9900067 W (CH 37298, aircraft door hinge) — not this patent.
• Indian High Court cause number APSWP 9900067/2001 — not this patent.

Consequence: I cannot present a verbatim, claim-by-claim table of the exact references cited on the '067 front page. Per the operating rule against fabrication, I will not invent a citation list. Instead, below I (A) report the one citation-data point I did confirm, and (B) give the technically on-point 802.11ac/VHT-SIG prior art I actually located, clearly labeled as candidate prior art in the same field — not certified as cited on the face of '067 — with a § 102 analysis and the priority-date caveat that governs whether each could even qualify.

Also noted: the task header says current date April 26, 2026, while the system context says 2026-09-19. This is the same inconsistency the prior "Litigation" section already flagged; I treat the later date as ground truth and do not let it affect the patent-art analysis (which is date-insensitive here).

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A. Citation data I could confirm

Note the distinction: "Cited By 6" is forward art (later patents that cite '067 as background), not the prior art examined against '067. Do not conflate the two.

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B. Candidate prior art in the same field (technically on-point; on-face citation unverified)

The '067 claims (per the earlier summary section) are directed to a receiver that gets (i) a two-OFDM-symbol first signal field (VHT‑SIG‑A) over a bandwidth that is a multiple of 20 MHz, (ii) a one-OFDM-symbol second signal field (VHT‑SIG‑B) whose content is the SIG‑B repeated a bandwidth-dependent number of times, (iii) common-vs-user-specific split between SIG‑A and SIG‑B, and (iv) SIG‑B carried on a selected spatial stream. The references below are the art that was in the air in this exact window (2009–2011 802.11ac drafting).

B1. Qualcomm — "Format of VHT‑SIG‑B and service fields in IEEE 802.11ac"

• Family: US 13/160,343 (filed 2011‑06‑14) → pub. US 2014/0198877 A1 (2014‑07‑17); WO 2011/159562; EP 2 577 927 (Qualcomm; inventors Van Nee, Van Zelst, Merlin, Sampath); priority US 61/354,930 (2010‑06‑15) and related US 201113149411 (2011‑05‑31).
• Where I found it: the RVO/EPO listing of granted EP patents (https://www.rvo.nl/.../IE_53_2015.pdf, entry "EP2577927 … Format of VHT‑SIG‑B and service fields in IEEE 802.11AC, Qualcomm") and FreePatentsOnline for US 2014/0198877 (https://www.freepatentsonline.com/y2014/0198877.html).
• Substance (highly material): express disclosure of the VHT‑SIG‑B bit budget by bandwidth — "twenty signal bits and six tail bits … if a transmission bandwidth is 20 MHz"; "one reserved bit and six tail bits … repeat the set … if 40 MHz"; "three reserved bits and six tail bits … repeat the set three times … if 80 MHz"; "160 MHz … repeat the group"; plus "copy the VHT‑SIG‑B onto a number of space-time streams that is the same as a number of space-time streams in the DATA field."
• § 102 potential: Claim 1 (SIG‑B content obtained by repeating a bandwidth‑dependent number of times; carried on the receiver's spatial streams) and dependent claim(s) reciting 26/27/29‑bit SIG‑B allocations. Caveat: priority 2010‑06‑15 is after '067's earliest priority (2010‑03‑12), so this is § 102 art only to '067 claims whose effective filing date is later than June 2010 (see §D).

B2. Qualcomm — "Constructing VHT‑SIG fields for reduced PAPR"

• Family: US 2012/0039198 A1 (pub. 2012‑02‑16; filed 2011‑08‑10; priority US 61/372,790, 2010‑08‑11); WO 2012/021624 A1; CA 2806235; JP 6325029 B2. Inventors Yang, Jones, Van Zelst, Sampath, Van Nee.
• Where found: FreePatentsOnline (/y2012/0039198.html), CA 2806235C PDF, and JP 6325029B2 (SumoBrain).
• Substance: construction/scrambling of the VHT‑SIG field (SIG‑A and SIG‑B) within the preamble; "example VHT‑SIG field values."
• § 102 potential: general § 102(a) art for the VHT‑SIG‑A/SIG‑B framework, but does not itself appear to disclose the bandwidth-scaled SIG‑B repetition or stream selection → weak standalone anticipation; better as § 103 background. Same June–August 2010 date problem.

B3. Qualcomm — "Method and apparatus for saving power by using signal field of preamble"

• US 2012/0182980 A1 (pub. 2012‑07‑19). Found at FreePatentsOnline.
• Substance: computes a CRC over the SIG field bits at the receiver and "may stop a decoding process if it fails to correctly decode" the VHT‑SIG‑A/VHT‑SIG field — i.e., power saving by early abort.
• § 102 potential: squarely relevant to the dependent claim reciting a CRC field used to detect errors in the second signal field and to the spec's teaching that "when an error of the scrambler seed is detected, the operation of PHY and MAC layers can be stopped … reducing power consumption." Date caveat applies (priority ~ Dec 2010/Jan 2011).

B4. Broadcom — "Group ID Concept for Downlink MU‑MIMO Transmission"

• IEEE 802.11‑10/0073r2, Joonsuk Kim et al., 2010‑03‑15. Found as an "Other Reference" cited on the face of Qualcomm's JP 6325029 B2.
• Substance: the Group ID by which a user determines which stream(s) to demodulate in DL MU‑MIMO — i.e., the common-vs-user-specific information split and the spatial-stream-selection concept.
• § 102 potential: the concept maps onto claim 1's "information common to the multiple receivers" and "at least one spatial stream … corresponding to the receiver." Date is three days after '067's earliest priority (2010‑03‑12) → § 102/§ 103 art only for later-effective-date claims.

B5. Qualcomm — "802.11ac Preamble"

• IEEE 802.11‑10/0876r0, Hemanth Sampath et al., 2010‑07‑13. Found in the EP 2 800 326 A3 search report (cited "Y" against claims 1–9 alongside WO 03/034674).
• Substance: 802.11ac preamble structure — legacy-compatible L‑SIG/L‑STF/L‑LTF followed by VHT‑SIG‑A/VHT‑SIG‑B; general 802.11ac frame layout.
• § 102 potential: § 102(a) background for claims 1 and 13 ("carried as a PPDU" / backward-compatible preamble); likely anticipates only the preamble-format elements, not the repetition logic.

B6. Lanante et al. — "IEEE 802.11ac Preamble with Legacy 802.11a/n Backward Compatibility"

• IEEE 802.11‑yy/0847r0, 2009‑07‑14 (slides 1–18). Cited as an "Other Reference" on JP 6325029 B2.
• Substance: designing the ac preamble so 802.11a/n devices still detect it. Pre-dates '067's priority (2009‑07‑14 < 2010‑03‑12) → clean § 102(a) art for dependent claim 2/3 ("first signal field received without applying MU‑MIMO" / "repeated over each 20 MHz sub-band") and the auto-detection/backward-compat limitation.

B7. Narasimhamurthy, Banavar & Tepedelenlioğlu — OFDM Systems for Wireless Communications

• Morgan & Claypool Publishers, 2010‑03‑10, pp. 32 et seq. (ISBN 1598297015). Cited "Y"/"A" in the EP 2 800 326 A3 report.
• Substance: textbook OFDM background (subcarrier/interleaving, diversity). § 102 potential: background (§ 102(b) printed publication); supports obviousness of interleaving/precoding, but a textbook is not a § 102 anticipation of the claimed SIG‑B repetition.

B8. WO 03/034674 A1 (Ericsson / van Nigtevecht et al.), 2003‑04‑24

• Cited "X" in the Qualcomm EP 2 800 326 A3 search report (relev. claims 1–9).
• Substance: OFDM preamble/signaling techniques. § 102 potential: only if a claim read on generic OFDM signaling; on its face it does not disclose MU‑MIMO SIG‑B repetition → more likely § 103 background.

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C. Which claims each candidate touches under § 102

No candidate I found reads on all elements of claim 1 and claim 10 simultaneously with clean dated status, so at this stage this is a § 103-combination picture, not a clean § 102 single-reference knockout — subject to the priority-date throttle below.

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D. The decisive date problem (why § 102 "anticipation" is fragile here)

'067's earliest priority is 2010‑03‑12 (KR 10‑2010‑0022122); the PCT was filed 2011‑03‑11, and the asserted claims are continuation claims of US 13/434,681. That means:

• For any '067 claim whose subject matter is supported by the 2010‑03‑12 disclosure, § 102 art must pre-date 2010‑03‑12. Under that date, B4 (2010‑03‑15), B1 (2010‑06‑15), B2 (2010‑08‑11), B3, B5 (2010‑07‑13) all post-date it and drop out; only B6 (2009‑07‑14) and B7 (2010‑03‑10) remain comfortably pre-critical-date.
• But '067's VHT‑SIG‑B bit-allocation / repetition-by-bandwidth subject matter (the FIGS. 45–48 material, the 26/27/29-bit allocation) appears to ride on the later Korean applications — 10‑2010‑0065898 (2010‑07‑08), ‑0066458 (2010‑07‑09), ‑0068167 (2010‑07‑14), ‑0072506 (2010‑07‑27). If those claims do not get the March 12 date (a standard § 112 written-description support question), the effective date slips to July 2010, which re-admits B1 (June 15) and B4 (March 15) — and potentially makes B1 a genuine § 102 reference.

Practical takeaway: whether the Qualcomm VHT‑SIG‑B-format reference (B1) anticipates the claim-1 repetition limitation turns entirely on the priority/§ 112-support determination for the SIG‑B repetition subject matter. This is exactly the kind of issue that would have been litigated in Sol IP v. AT&T/Sprint (E.D. Tex. 2:18‑cv‑00526/‑527/‑528) and is worth pulling from the invalidity contentions if you can access PACER.

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E. How to obtain the authoritative face-citation list (so this can be closed out)

1. USPTO PatentCenter / PAIR for application 14/147,447 → "References Cited" (56) and the PTO‑892/1449 forms — the definitive list.
2. Google Patents → US9900067B2 → "Patent Citations" table (the sections that were truncated in the text I received).
3. WIPO Patentscope / EP Register for the parent PCT/KR2011/001742 → the ISR (PCT/ISA/210) "Documents Considered Relevant," which is the search-examiner's own prior-art list and the best proxy for what the family's examiners treated as art.
4. The related EP family member (EP 4020830 A1, same title) → its EPO search report lists cited art with X/Y/A categories.

Everything in Section B should be re-checked against items 1–4 before being called "cited by '067." Section B is technically sound as prior art in the field, but I have not verified that any particular reference appears on the '067 face.

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F. Confidence and flags

Two explicit flags carried forward: (1) the prompt/system date contradiction (Apr 26 vs. Sep 19, 2026) noted earlier; and (2) the fact that no CAFC/IPR activity was located in the earlier sections is a general-search negative result, not a complete docket check — and it bears on prior art only indirectly (a PTAB IPR, if one existed, would carry the petitioner's own art list, which is another route to the definitive references).

Obviousness Analysis — US 9,900,067 B2 under 35 U.S.C. § 103

Built on: the "Patent summary" (claim 1 / claim 10 element set), "Prior art" (§B candidate references B1–B8), and "Assignment history" sections. I do not repeat their content, except where a point must be carried forward to make the obviousness reasoning work.

Carried-forward caveats (they control the confidence of everything below):

1. The claim text is not certified. The "Patent summary" section took claim 1/claim 10 from a publication-stage reproduction of US 2014/0119327 A1, not the granted text of '067. Every mapping below is "as-construed-from-the-publication," and a granted-claim re-read could move the goalposts. This is the single biggest risk to the analysis.
2. The date throttle from the Prior art section §D. '067's earliest priority is 2010-03-12; B1/B4/B5/B2/B3 post-date it. Whether they are even available as § 103 art turns on the effective filing date of the claims. I treat this as the pivotal issue, not a footnote.
3. Prompt/system date contradiction (2026-04-26 vs 2026-09-19) — irrelevant to claim-art dating, noted only for consistency.

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1. Legal framework and the level of ordinary skill

Pre-AIA § 103(a) governs (assuming the claims hold their 2010 priority). The application 14/147,447 (filed 2014-01-03) is a continuation of 13/434,681 (2012-03-29), itself a continuation of PCT/KR2011/001742 (2011-03-11). Because the effective filing date is carried back before 2013-03-16, the AIA §§ 102/103 do not apply to claims entitled to that priority — pre-AIA § 102/§ 103 control. Among other things, this means pre-AIA § 102(e) (a published application is art as of its filing date) and pre-AIA § 103's requirement that the art qualify under § 102 both matter.

Graham factors frame the analysis: (1) scope/content of the prior art; (2) differences between the art and the claims; (3) the PHOSITA's level of skill; (4) secondary considerations.

KSR v. Teleflex supplies the motivation-to-combine vocabulary used below: (a) combining prior-art elements by known methods to yield predictable results; (b) simple substitution of a known element for another to obtain a predictable result; (c) use of a known technique to improve a similar device in the same way; (d) applying a known technique to a known device ready for improvement; (e) "obvious to try"; and (f) design incentives / market forces, including standardization pressure.

PHOSITA (proposed): a B.S. in EE or equivalent with ~2–4 years' experience in OFDM/MIMO wireless PHY design, familiar with the IEEE 802.11 family and the then-active 802.11ac (TGac) drafting, and with the frame/preamble structures of 802.11a/n (L-STF/L-LTF/L-SIG preamble, VHT signaling). The '067 inventors' own field (ETRI project 10MI3500, "IEEE 802.11 VHT") is squarely this PHOSITA.

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2. The obviousness target — claim 1 decomposed

Stripping claim 1 to its limitations (per the earlier summary) gives five independently-mappable elements:

Key structural observation for § 103: L1, L2, L4 (mostly), and L5 are frame-architecture / standard-format features. The only limitation with any algorithmic content is L3, and L3 recites the plain repetition ("repeating a SIG-B a predetermined number of times") that the specification itself disparages as the prior-art baseline. The specification's actual point of novelty — different interleaving per stream / CDD / per-antenna delay — is not in claim 1 at all (it appears only in FIGS. 4–5, 11–57 discussion). That is the threshold obviousness lever, addressed in §8.

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3. What the prior art supplies (cross-referenced, not repeated)

From the Prior art section:

No single reference reads on all five elements with a clean date. The picture is therefore combination-based § 103, with B1 as the primary reference (it alone carries L3) and B4/B5/B6 supplying L1/L2/L4/L5.

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4. Primary § 103 combination — B1 + B4 + B6 (+ B5)

The combination: B1 (Qualcomm VHT-SIG-B format) as the primary reference, combined with B4 (Broadcom Group ID / stream selection) and B6 (802.11ac backward-compatible preamble, with B5 as a same-class corroborating preamble disclosure).

4.1 Element-by-element

Every limitation of claim 1 is met by the four-reference set, and L3 is met by B1 alone.

4.2 Motivation to combine (KSR rationales)

1. Same problem, same forum, same standard (KSR (f), design incentive). B1, B4, B5 are all TGac contributions/proposals directed to the same 802.11ac preamble. B4's Group ID and B1's VHT-SIG-B are complementary pieces of one frame format — a PHOSITA drafting the ac PHY would have been led, as a matter of course, to specify both the common field (B5/B6) and the per-user B field (B1) together. Combining references that describe different fields of the same mandated frame is about as strong a "design incentive" as exists.

2. Known technique, predictable result (KSR (a)/(c)). Repetition (B1's "repeat the set / repeat the group") is a routine diversity/robustness technique; applying it "to a known device ready for improvement" (the ac signaling field) is predictability personified. The specification itself treats repetition as the known baseline.

3. Simple substitution of a known element (KSR (b)). B4's Group ID is the known mechanism for stream selection in DL MU-MIMO; substituting it into the B1 frame to satisfy "receiver selects its spatial stream(s)" yields the claimed result with no change in the principle of operation.

4. Corroboration across independent actors (KSR, "obvious to try"). That Qualcomm (B1/B5) and Broadcom (B4) independently converged on the same fields for the same TGac format is strong evidence the claimed arrangement was the natural, expected design, not a nonobvious departure.

4.3 Reasonable expectation of success

The combination is not speculative: B1 already publishes the exact repetition counts (1× at 20/40, 3× at 80, group-repeat at 160) and already copies SIG-B across space-time streams. What claim 1 adds is only the receiver-side recitation of the same transmitted structure. The '067 inventors, describing their own transmission scheme, characterize the SIG-B iteration as efficiency engineering, not a new signaling principle — consistent with a high expectation of success.

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5. Alternative and secondary combinations

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6. Dependent claims (2–9, 11–13) — mostly one-step obviousness

The dependent claims add, per the earlier summary: (a) first signal field received without MU-MIMO; (b) first field repeated over each 20-MHz sub-band; (c) fields are VHT-SIG-A / VHT-SIG-B; (d) SIG-B is 26/27/29 bits at 20/40/>40 MHz; (e) data field includes a CRC detecting errors in the second signal field; (f) carried as a PPDU.

• (a) and (b) map to B6 + B5 (legacy/common signaling and per-20-MHz repetition of the common field) and are additionally the specification's own description of how VHT-SIG-A behaves (the "Patent summary" section's specification mapping). These are format conventions.
• (c) VHT-SIG-A/B nomenclature is supplied by B1/B5 by name.
• (d) the 26/27/29-bit allocation by bandwidth is expressly in B1 (twenty signal bits + six tail bits at 20 MHz; reserved + tail with repeat at 40; three reserved + tail, repeat ×3 at 80; group-repeat at 160). This is a direct § 102-style hit on the dependent-claim bit allocation, subject only to the date question.
• (e) CRC-on-SIG is B3; motivation is the power-save benefit B3 itself states (and the spec's own "stop PHY/MAC … reducing power consumption").
• (f) PPDU is B5/B6.

Result: no dependent claim introduces a limitation that requires more than a single additional reference beyond the primary combination.

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7. Claim 10 (receiver apparatus) — obviousness tracks claim 1

Claim 10 is the apparatus counterpart (reception unit + data obtaining unit) with the identical L1–L5 limitations. Apparatus claims whose novelty resides wholly in a method/frame structure are obvious whenever the corresponding method is obvious — there is no separate structural ingenuity (a generic receiver front-end + decoder). B1 + B4 + B6 disposes of claim 10 on the same reasoning as claim 1. No claim of unexpected apparatus behavior is even asserted in the specification.

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8. The specification's own admissions — the strongest § 103 lever

This is the point to lead with if the art dates survive (§9):

• The Background/Disclosure concedes that simple iteration of the common signal field produced an SNR gain, and that "even when VHT-SIG B is transmitted by using the simple iterative structure like VHT-SIG A, VHT-SIG B cannot obtain both an SNR gain and a frequency diversity gain." The premise that repetition of a signal field across a variable bandwidth was known is thus an admission — and it is exactly what claim 1's L3 recites.
• The specification locates the alleged invention in the different-interleaving-per-stream / CDD / per-antenna-delay refinement (FIGS. 4–5, 11–57), and in bit-allocation-by-bandwidth (FIGS. 45–50). Claim 1 recites neither. It recites plain repetition.
• Consequence: claim 1 is broader than the disclosed invention and reads on the admitted prior art. A claim is not saved from § 103 by novelty that resides only in unclaimed embodiments. Where the specification says "plain repetition was known but insufficient, and our improvement is interleaving," a claim that captures plain repetition is squarely obvious (and arguably anticipated) over B1, which already taught bandwidth-scaled repetition.

Put differently: the patent's own narrative gives the accused infringer a built-in admission that the claim-1 algorithm was the starting point, not the destination.

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9. The date throttle — decisive and unresolved

This is where the analysis can swing from "strong § 103 combination" to "the art isn't even available."

• If claim 1 (and the 26/27/29-bit dependent claim) are entitled to 2010-03-12, then B1 (2010-06-15), B4 (2010-03-15), B2 (2010-08-11), B5 (2010-07-13), and B3 all post-date the critical date and drop out for those claims. Only B6 (2009-07-14) and B7 (2010-03-10) remain comfortably pre-critical-date — but neither discloses L3 (bandwidth-scaled VHT-SIG-B repetition), so the clean B1-driven anticipation/obviousness collapses and the case becomes a weaker B6 + B7 + general-knowledge obviousness theory.
• If, however, the VHT-SIG-B bit-allocation/repetition subject matter (the FIGS. 45–48 material; the 26/27/29-bit allocation) is not supported by the 2010-03-12 disclosure — a § 112 written-description question tied to the later Korean filings (KR 10-2010-0065898 of 2010-07-08, ‑0066458 of 2010-07-09, ‑0068167 of 2010-07-14, ‑0072506 of 2010-07-27) — then the effective date for those claims slips to July 2010, which re-admits B1 (06-15) and B4 (03-15) and converts B1 into both § 102(e)/§ 102(a) art and the linchpin of the § 103 combination.

Bottom line: the strength of the § 103 attack is a function of the priority determination. B1 is simultaneously (i) the best § 103 reference and (ii) the reference whose availability is most date-fragile. Counsel should treat the effective filing date of the repetition/bit-allocation claims as the first-ordered issue.

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10. Anticipation vs. obviousness posture

• Clean single-reference § 102 anticipation is not established for claim 1, because no located reference discloses all of L1–L5 with clean dated status (only B1 carries L3; B4 carries the stream-selection split; B6/B5 the two-symbol common field).
• § 103 is the right theory, not § 102, for claim 1/claim 10. The strongest framing is B1 as primary + B4 + B6/B5, with B1 alone sufficient for the dependent 26/27/29-bit claim if the priority date slips.
• Per KSR, a "combination of references" need not be physically combinable as a product; it is enough that the references are from the same field and the combination is the predictable, design-driven outcome — which the TGac convergence of B1/B4/B5 satisfies.

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11. Rebuttal considerations / secondary considerations

A patent owner (Sol IP — see the Assignment and Litigation sections) would likely argue:

1. Teaching away: the specification disparages "protect[ing] the VHT-SIG B more than necessary" via iteration. Counter: disparaging an efficiency of a known technique is not a teaching away from the claim; the claim still recites the technique. KSR requires a teaching away from the claimed subject matter, and the spec's improvement (interleaving) is outside claim 1.
2. Priority support: the patent owner will argue the March-12 disclosure supports the repetition claims, to knock B1/B4 out. Counter: test the written-description support against the actual Korean priority texts (§9).
3. Secondary considerations (unexpected results, long-felt need, industry praise, licensing): None are in the record I can cite. No unexpected-results data appears in the specification; the tone is efficiency-tuning. If Sol IP relies on licensing/pool success (Avanci Wi-Fi 6 Vehicles — see the Litigation and Assignment sections) as a nexus, that is a commercial-success argument that is weak absent a proven nexus to the claimed repetition (the pool success is more plausibly attributable to SEP status than to the SIG-B repetition feature). No IPR has tested these claims (PTAB section), so there is no prior Board treatment to cite either way.
4. Standard-essentiality estoppel dynamics: if the claims are essential to 802.11ac, the art that defines 802.11ac (B1/B4/B5) is, almost by definition, prior art to a patent claiming the same standard behavior — a point that cuts toward invalidity but whose priority interplay must be resolved first.

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12. Confidence, flags, and next steps

What would change the analysis (priority-ordered verification steps):

1. Certified granted-claim text for '067 (not the publication reproduction) — the entire mapping is contingent on it.
2. Effective-filing-date determination per claim — pull the four later Korean priority documents (KR 10-2010-0065898/-0066458/-0068167/-0072506) and map written-description support for the repetition and 26/27/29-bit subject matter. This is the make-or-break issue for B1/B4 availability.
3. Authoritative face-citation list (Prior-art §E): PatentCenter application 14/147,447 "References Cited," and the PCT/KR2011/001742 ISR "Documents Considered Relevant." If B1's family (or the same Qualcomm disclosure) appears there, the examiner's own framing supports the § 103 theory; if the examiner overcame it, the record shows how — useful both ways.
4. Invalidity contentions from Sol IP v. AT&T/Sprint/Verizon (E.D. Tex. 2:18-cv-00526/-527/-528) and any 2026 automotive-case disclosures, to see the art the defendants actually asserted (and the priority argument they made).

One-line verdict: If the claims keep the 2010-03-12 priority, the § 103 attack weakens materially (B1/B4 drop out and only B6/B7 remain, with no reference disclosing bandwidth-scaled SIG-B repetition). If the repetition/bit-allocation claims slip to July 2010, B1 (primary) + B4 (stream selection) + B6/B5 (common two-symbol field/PPDU), motivated by the single shared 802.11ac design, renders claims 1 and 10 obvious, with B1 alone reaching the 26/27/29-bit dependent claim and B3 reaching the CRC dependent claim — reinforced by the specification's own admission that plain repetition was the known baseline.