US 8867574

I'll search for authoritative information on this specific patent number, including any litigation/docket activity.

Let me check specifically for litigation/docket activity and verify the claim set.

Let me verify the independent claim set and check for any PTAB/docket records specific to this number.

US Patent 8,867,574 — Analysis Summary

Important caveat up front: I could not access USPTO Patent Center/PAIR or the CAFC docket system directly through the tools available here. The bibliographic and specification data below come from the authoritative full text of the patent (US8867574B2, fetched from Google Patents) plus corroborating public sources. I found no evidence of any litigation, ITC investigation, or PTAB proceeding involving US 8,867,574 specifically, and no CAFC 2026 docket entry naming it. That is an absence of evidence, not proof of absence — a name-confusion risk also exists because Qualcomm's better-known 2017 ITC/Apple action (Inv. No. 337-TA-1065) asserted different patents (8,633,936; 8,698,558; 8,487,658; 8,838,949; 9,535,490; 9,608,675), not 8,867,574.

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Bibliographic Data (literal, as recorded)

Abstract (as published)

"Methods and apparatus for transmitting and receiving frames with various Very High Throughput Signal B (VHT-SIG-B) and Service field formats are provided. Some of these formats may be in accordance with the IEEE 802.11ac amendment to the wireless local area network (WLAN) standard."

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Plain-Language Overview of the Independent Claims

The patent is directed to the preamble of an IEEE 802.11ac ("VHT") packet — specifically the one-OFDM-symbol VHT-SIG-B field that tells a station how long the useful data in the packet is. The claims fall into four recurring families, each drafted as a transmit method, a receive method, a hardware apparatus (including means-plus-function versions), and a computer-program-product version:

Family A — Matching subcarrier counts (Figs. 5–6 / 5A–6A)

• Transmit side (e.g., Claim 1): Generate a frame with a preamble and a data portion, where the preamble includes a field (the VHT-SIG-B field) indicating the length of useful data in the data portion, and both that field and the data portion use the same number of subcarriers; then transmit the frame. The specification gives 56 subcarriers for 20 MHz, 114 for 40 MHz, 242 for 80 MHz, and 484 for 160 MHz.
• Receive side (e.g., Claim 41): Receive such a frame and decode the data portion based on that field (and stop decoding when the indicated useful-data length is reached). A further receive-side variant adds the negative limitation that the total power of the VHT-SIG-B field equals the total power of a preamble training field even though the per-tone power differs.

Family B — Bit repetition tied to channel bandwidth (Figs. 7–9 / 7A–8A)

• Transmit side (e.g., Claim 77): Generate a frame with a preamble carrying a VHT-SIG-B field indicating useful-data length, and transmit it over a channel; the generating step includes determining the channel bandwidth, generating a block of bits based on that bandwidth, and repeating that block a number of times according to the bandwidth to form the VHT-SIG-B field. Fig. 9 shows the worked examples: a 27-bit block repeated twice (40 MHz → 54 bits), a 29-bit block repeated four times plus a reserved bit (80 MHz → 117 bits), and the same 29-bit block repeated eight times plus two reserved bits (160 MHz → 234 bits).
• Receive side (e.g., Claim 101): Receive a frame whose VHT-SIG-B field comprises a plurality of replicated blocks, such that bits of one block are repeated in each of the other blocks, and decode the data portion based on that field.

Power-scaling dependent concepts also appear as positive limitations in some independent claims (Claims 31, 95, and others), where the processing system/instructions must apply power scaling so the VHT-SIG-B total power equals the preamble training field's total power while permitting different per-tone power.

Confidence note on the independent claim set

What I can state with high confidence: the patent has 128 total claims, and the patent/specification describes on the order of four to eight independent-claim families spanning transmit-method, receive-method, apparatus, means-plus-function, and computer-program-product forms. Public claim listings (RPX/Insight) surface independent claims at least at Claims 1, 31, 41, 50, 59, 68, 77, 83, 89, 95, 101, 108, 115, and 122. I could not authoritatively confirm the complete and exact set of independent claims (i.e., whether claim 11 and/or 21 are also independent) from the sources available. Treat the specific independent-claim numbers as unverified and confirm against the USPTO Patent Center claim listing before relying on them.

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Litigation / Docket Status

• CAFC 2026 dockets: No Federal Circuit appeal naming US 8,867,574 was found.
• PTAB: No IPR/PGR petition naming US 8,867,574 was found.
• District court / ITC: No infringement action asserting US 8,867,574 was found. The Qualcomm–Apple ITC Complaint (July 7, 2017) and resulting investigation 337-TA-1065 asserted six non-SEP patents — 8,487,658; 8,633,936; 8,698,558; 8,838,949; 9,535,490; and 9,608,675 — none of which is 8,867,574.

Given the strict instruction not to auto-correct or substitute similar numbers, I am explicitly not treating the '574-family neighboring patents or the '675–'674 group from the Qualcomm/Apple proceedings as the same patent as 8,867,574.

Uncertainty declaration: My searches of public web sources did not turn up an authoritative USPTO assignment/reassignment record beyond the August 2, 2011 assignment to QUALCOMM INCORPORATED, nor any confirmed post-issuance reissue, reexamination, or disclaimer history. A direct Patent Center / CAFC PACER check is recommended to confirm the "no litigation" conclusion for this specific number.

I'll research litigation involving US Patent 8867574 across patent litigation databases.

Let me search targeted litigation databases and the specific patent number.

Let me check the Unified Patents portal and other litigation databases directly.

Litigation Search Results for U.S. Patent No. 8,867,574

Summary: No litigation involving U.S. Patent No. 8,867,574 was identified in the sources searched. I was unable to confirm any district court action, ITC investigation, CAFC appeal, or PTAB post-grant proceeding asserting or challenging this specific patent.

What I searched

• General web queries for "US patent 8867574 litigation" and "8867574 patent lawsuit defendant"
• Quoted exact-number searches: "8,867,574", "8867574"
• Cross-references against Qualcomm's known patent campaigns (Qualcomm v. Apple, SDCA 3:17-cv-01375; ITC Inv. Nos. 337-TA-1065, 337-TA-1093) and against Unified Patents' portal/caselist pages

Notably, none of the hits returned bore the number 8,867,574. The results that did appear concerned unrelated patents (e.g., U.S. 7,946,788 / 8,511,932 / 8,690,474 in Wirtgen America v. Caterpillar; U.S. 8,036,756 / 8,626,314 in Medtronic v. Axonics; Qualcomm's asserted patents in the Apple dispute — U.S. 8,633,936, 8,698,558, 8,487,658, 8,838,949, 9,535,490, 9,608,675). Per your instruction, I have not substituted any of these similar numbers for the target patent.

Corroborating signal

The authoritative Google Patents record you supplied for US 8,867,574 lists assignee Qualcomm Inc., priority date 2010-06-02, grant date 2014-10-21, and adjusted expiration 2032-12-19. That record contains no litigation entries — only a generic "Discuss" link, no case list — consistent with a patent that has not been asserted in a reported U.S. action.

Required fields for each case

Because no case was identified, there are no entries to populate for plaintiff(s), defendant(s), jurisdiction, case number, filing date, or outcome/current status.

Important caveats

1. Search limitations. My tooling is a general-purpose web search, not a native query of a litigation docket database. I was also cut off by a step limit before completing the portal-specific queries (Unified Patents caselist filtered to this patent, Docket Navigator, RPX Insight, CourtListener RECAP, PACER, ITC EDIS). The absence of results is therefore not proof of absence of litigation.
2. Non-public and non-indexed activity. Licensing demands, settlements, arbitration, and complaints that were dismissed or sealed very early may never appear in public indexes.
3. PTAB/IPR caveat. A post-grant proceeding (IPR/PGR) against this patent would appear in PTAB records rather than litigation dockets; I found no evidence of one, but could not exhaustively confirm this.
4. Recommendation for confirmation. To verify definitively, run the number as an exact string against: (a) Unified Patents litigation portal — https://portal.unifiedpatents.com/litigation/caselist; (b) CourtListener/RECAP and PACER Docket Search; (c) Docket Navigator; (d) the ITC EDIS system. Note that Docket Navigator and PACER require subscription/account access.

Bottom line: Based on the searches performed and the authoritative patent record, I have no known litigation to report for U.S. Patent No. 8,867,574, and I am stating that explicitly rather than inferring cases from similarly numbered patents.

I'll verify the ODP result against public sources before writing up.

Let me run a couple more targeted checks before concluding.

One more check for any later-filed challenge or litigation use.

Proceedings overview

Total AIA trial proceedings on US 8,867,574: 0. The USPTO Open Data Portal returns no IPR, no PGR, and no CBM proceedings — so the breakdown is 0 active / 0 invalidated / 0 sustained / 0 settled / 0 institution-denied, and the defensive posture is simply this: there is no PTAB kill shot to cite, but also no PTAB estoppel shield — the patent is 100% untested at the Board, and an IPR petition against it is still an open move for a defendant who is not time-barred.

I independently searched for a proceeding the ODP ingest might have missed (Qualcomm/802.11ac VHT-SIG-B challenges, "8,867,574" + IPR/PGR, and the third-party PTAB case trackers). The Qualcomm-vs-Apple-Intel IPR wave of 2018 that surfaced in those searches involves Qualcomm patents such as 9,608,675, 8,768,865, 8,698,558, and 8,971,861 — not the '574 patent. I found no docket entry, FWD, institution decision, appeal, or settlement touching US 8,867,574. I am flagging that as "not found," not as "conclusively disproven" — see the diligence caveat below.

Because there is no proceeding to walk through, the usual per-proceeding template is inapplicable. Substituted below is what a defendant actually needs.

No proceedings on file — diligence note

• Type / Filed / Status / Judge panel / Petition grounds / Institution decision / FWD / Settlement / Appeal: N/A for all — no proceeding exists.
• Caveat on confidence: ODP is the canonical structured source and it is silent here. My cross-check was web search, which is good at surfacing reported proceedings and weak at surfacing denied, un-indexed, or recently filed ones. A petition filed in the last ~3–6 months could exist without showing up in either source. Verify directly in PTAB E2E / PTAB Center (ptacts.uspto.gov) using "Application/Control No. 13/149,411" or "Patent No. 8867574" before you rely on the absence in a brief.

Procedural clock facts that follow from "zero proceedings"

• PGR is off the table. PGR must be filed within 9 months of grant. The patent granted 2014-10-21, so the PGR window closed 2015-07-21. No PGR — and no CBM either (CBM sunset under SAS/§ 18 of the AIA and is effectively unavailable now regardless).
• IPR is still live in principle. The patent's adjusted expiration is 2032-12-19, so it is nowhere near the end of its term. IPR has no age deadline — the only petitioner-side bar is the § 315(b) one-year clock running from service of a complaint alleging infringement. A defendant who has not yet been served, or was served less than a year ago, can still file.
• The real 2026 headwind is discretionary denial, not statutory eligibility. Current USPTO practice has been denying large numbers of IPR petitions against older patents under a "settled expectations" rationale, and applying Fintiv-style discretion where there is parallel litigation. A 2014-issued, 2010-priority patent is squarely in that risk zone. That is a reason to file early, document why the art is not cumulative, and avoid a stay/parallel-litigation posture that hands the Board a discretionary-denial hook.

Strategic summary

Claim status: every claim of US 8,867,574 is UNTESTED. No claim has been canceled, none has been confirmed, and none has been construed by the Board. There is no FWD to quote and no claim numbers I can accurately recite as "canceled" or "sustained" — and I will not invent any. Practically, that cuts both ways: the patent owner cannot point to a PTAB win for strengthened presumption or § 325(d)/§ 315(e) leverage, and a defendant cannot point to a PTAB loss to argue the claims are already dead. The full claim set stands as issued, backed only by prosecution history and whatever a district court does with it.

Estoppel landscape: there is none — § 315(e)(2) has never been triggered. IPR estoppel runs only after a final written decision. With no FWD, no petitioner is estopped, no privy is estopped, and no ground is off the table for anyone. Combined with the fact that the '574 patent is an 802.11ac preamble-structure patent (VHT-SIG-B subcarrier count, bit repetition across bandwidths, Service-field length coding) that was drafted during active TGac standards activity in 2010, the prior-art universe is unusually rich: the IEEE 802.11ac draft submissions, TGac meeting contributions, and the competing Qualcomm/other-vendor proposals contemporaneous with the 2010-06-02 priority date are all fair game on § 102/§ 103. The flip side is § 325(d) — if the examiner already considered the key TGac documents, a petitioner must explain the error, not just re-assert the same art.

Pattern signals: nothing to pattern-match. There is no serial petitioner, no defensive aggregator (no Unified Patents or RPX-administered challenge on this patent), and no PTAB-appeal aggressiveness by Qualcomm as to this patent, because there is no proceeding at all. Note that this is not evidence of a weak patent — it is more likely a function of this being a Qualcomm-owned portfolio patent caught up in the Apple/Intel licensing wars of 2017–2019, where the parties IPR'd a targeted subset (the '675, '865, '558, '861 family) rather than the whole portfolio. An unchallenged Qualcomm Wi-Fi patent generally means "not selected for attack," not "unattackable." It also means the record is clean: no adverse claim constructions, no patent-owner disclaimers, no prosecution-history estoppel generated by trial conduct — things that often make a PTAB-tested patent easier to defend in court.

Recommended next steps

• If you are a defendant receiving an assertion letter citing this patent: confirm in PTAB E2E that no petition is pending or filed, then treat the patent as fully live and fully challengeable. Because there is no FWD, § 315(e)(2) estoppel does not bar anything — every § 102/§ 103 ground you can develop from the 2010-era TGac record is available both in an IPR and in the district court, with no estoppel overlap risk to manage. Check your § 315(b) service date first; that is the one hard deadline.
• If you are considering a petition: move early. Given current discretionary-denial practice against older patents, build the petition around art that is demonstrably not cumulative to the '574 prosecution history and, if you are also in litigation, be prepared to address Fintiv/parallel-litigation discretion head-on. Target the independent claims and the bandwidth-dependent structure that the specification itself describes as "unresolved issues" (subcarrier count, pilot mapping, length-field encoding) — that framing is useful for showing the claims were convention, not invention.
• If you are the patent owner defending an assertion: the absence of PTAB activity is a genuine asset — no FWD means no claim cancellations, no Board claim constructions to fight, and no estoppel-tainted record. Do not let a defendant characterize the patent as "lightly tested"; it is untested, which is a neutral fact, and your § 282 presumption is intact and unweakened.
• Link/verify: patent text at patents.google.com/patent/US8867574/en; PTAB dockets at PTAB Center; Federal Circuit opinions via CourtListener (I checked; no appeal record surfaced) and cafc.uscourts.gov.
• Bottom line, plainly stated: there are no AIA trial proceedings on US 8,867,574. No claims are canceled, no claims are confirmed, nobody is estopped, and PGR is foreclosed by the 2015 window closure. IPR remains available to a non-time-barred defendant, subject to the current discretionary-denial climate for older patents. Re-check PTAB E2E immediately before filing or briefing, since the absence of a proceeding is a snapshot, not a warranty.

I'll research the assignment record for US 8867574. Let me start with the primary sources.

Let me check for any post-issuance transfers or NPE activity on this patent.

Let me try to pin down the specific reel/frame for the Qualcomm assignment.

Inventors

All four are named in the recorded inventor→Qualcomm assignment, each with the mailing address 5775 Morehouse Drive, San Diego, CA 92121‑1714. Van Nee and van Zelst are Netherlands‑resident but Qualcomm‑employed (the same two appear as Qualcomm inventors on related 802.11ac filings, e.g. US 9,876,542 "Beamforming feedback format," Qualcomm assignee). Simone Merlin likewise recurs on other Qualcomm 802.11ac/MU‑MIMO filings.

Unusual patterns: None. This is a standard corporate-employee invention team with no evidence of inventors departing the assignee within 12 months, no co‑assignment to a third party, and no inventor‑retained rights recorded. There is no fire‑sale precursor pattern.

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Original assignee

Qualcomm Incorporated (Delaware corporation; 5775 Morehouse Drive, San Diego, CA 92121‑1714). Named as assignee on the face of US 8,867,574 and as the sole receiving party on the one recorded assignment.

• Line of business: Fabless semiconductor / wireless R&D and licensing. Qualcomm is the largest baseband/Wi‑Fi chipset vendor and an active SEP/portfolio licensor.
• Did they ship a product embodying the claims? Yes. The claims are directed to 802.11ac (VHT) preamble formatting — specifically VHT‑SIG‑B subcarrier usage and per-bandwidth bit repetition, plus Service‑field length signaling. Qualcomm's Qualcomm Atheros / Snapdragon Wi‑Fi chipset families implement 802.11ac VHT preamble generation and reception directly; this is a standards-implementation patent, not a paper patent.
• Current status: Operating, publicly traded (NASDAQ: QCOM), not acquired/dissolved and not in bankruptcy. Patent is listed on Google Patents as Active, expires 2032‑12‑19 (with terminal-disclaimer/PTA-adjusted term).

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Assignment timeline

Data limitation, stated up front: I was able to confirm the existence of exactly one assignment record through the Google Patents legal-events feed (which mirrors USPTO assignment data) but was not able to retrieve the reel/frame number or the correspondent-of-record for it from the sources reachable in this session. I will not invent a reel/frame. The USPTO Assignment Center entry should be verified at the link at the bottom of this report.

• Executed ~2011‑05/06 (pre‑filing–filing window) / recorded 2011‑08‑02 — Reel/Frame not captured (see data limitation above)
  • Conveyance: Assignment of Assignors' Interest — Assignor: Didier Johannes Richard Van Nee; Albert van Zelst; Simone Merlin; Hemanth Sampath
  • Assignee: QUALCOMM INCORPORATED, 5775 Morehouse Drive, San Diego, CA 92121‑1714
  • Correspondent: not retrievable from the sources used — no recurrence finding can be made.
  • Context: original inventor-to-employer assignment — the routine pre‑issuance assignment of employee inventions; not an acquisition, fire-sale, reorg, or securitization.

No post‑issuance assignments are recorded. Google Patents legal events for US 8,867,574 show only: (a) 2011‑05‑31 application filing by Qualcomm; (b) 2011‑08‑02 assignment to Qualcomm Inc.; (c) 2014‑10‑21 grant; (d) the foreign-family priority records (EP 2577927, JP 5763182/6151293, KR 101556638, CN 102948123/106899534, ES 2553083, BR 112012030620, CY 1117017) that all share the 2011‑06‑02 PCT priority. There is no change of name, merger, security agreement, license, release, correction, or transfer-to-asserter entry. That absence is the finding: Qualcomm still owns the patent.

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Timeline diagram

timeline
    title Ownership of US 8867574
    2010 : Priority filed
    2011 : Application filed
    2011 : Assigned to Qualcomm Incorporated
    2014 : Patent issued to Qualcomm
    2014 : No further transfers recorded

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NPE / troll-pattern signals

1. Shell-entity transfer — not present. The only recorded assignee is Qualcomm Incorporated, an operating semiconductor company at 5775 Morehouse Drive. No "IP / Holdings / Licensing / Ventures" suffixed entity, no registered-agent service address, no single-member LLC appears anywhere in the record (recorded 2011‑08‑02; no later entries).

2. Known asserter in the chain — not present. Neither the assignor group nor the assignee matches any entity on the public NPE lists (Acacia, Marathon, IV, IPNav, Wi‑LAN, Conversant/Mosaid, Vringo, Pendrell, Innovatio, MPHJ, Lumen View, Round Rock, Document Generation Corp, Spangenberg entities). Qualcomm is a practicing manufacturer and a frequent defensive and offensive litigant, but it is a supplier, not an NPE.

3. Repeat correspondent across the chain — not present / unclear. Only one assignment exists, so recurrence cannot exist by definition, and the correspondent of record for that single entry was not retrievable here. No finding.

4. Cascading transfers — not present. There are zero post‑issuance links, so there is no chain of LLCs and no <24‑month cascade. One assignment in 13+ years since filing.

5. Pre-litigation transfer — not present. No assignment is dated within 6 months of any infringement suit naming this patent (no such suit is recorded, and the sole assignment precedes issuance by ~3 years).

6. Bankruptcy fire-sale — not present. Qualcomm has not filed Chapter 7/11 and no reorganized-debtor entity appears in the chain.

7. Privateering — not present. No transfer out of Qualcomm to any asserting vehicle or proxy. The patent has not left the original operating-company owner.

8. Defensive aggregator — not present. The chain does not terminate at RPX, AST, LOT, Unified Patents, or OIN — it simply never leaves Qualcomm. (Inverse inference also fails: the patent has not been neutralized by an aggregator; it remains in the portfolio of an active litigant.)

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Verdict

Insufficient data — in the specific, benign sense defined by the rubric: the Assignment Center record consists of the original inventor→Qualcomm assignment only (recorded 2011‑08‑02), with no post‑issuance conveyances of any kind (no shell transfer, no security interest, no merger, no change of name). All eight NPE signal categories resolve to not present, because each requires a post‑issuance transfer that does not exist in this record; the one non‑retrievable datapoint is the reel/frame and correspondent for that single 2011 assignment, which does not affect the outcome. Practically, the ownership picture is clean and non-troll: a 2014‑granted 802.11ac standards-implementation patent that remains with its original operating-company assignee, Qualcomm Incorporated, an active chipset vendor and litigant.

Verification: search patent number 8,867,574 at the USPTO Assignment Center — https://assignmentcenter.uspto.gov/ (mirrored at https://assignment.uspto.gov/patent/index.html) — and compare against the Google Patents legal events at https://patents.google.com/patent/US8867574/en. Note that if the Assignment Center returns only the single 2011 assignment, this report's conclusion stands; if it returns any additional entry, the reel/frame and correspondent should be captured and signal 3 re-scored accordingly.

I'll research the prior-art citations on the face of US 8,867,574. Let me run several targeted searches.

Let me get the Justia page, which typically reproduces the front-page citations.

Let me pull the front-page citation lists from patent databases that reproduce them.

I hit the tool-call limit mid-investigation. Here is what I was able to establish, with the gaps stated explicitly rather than filled in by inference.

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Prior-Art Analysis — US 8,867,574 B2

1. Target identification (confirmed, USPTO-record data)

Governing law: priority 2010-06-02 and filing 2011-05-31 are both before 2013-03-16, so pre-AIA 35 U.S.C. §§ 102(a)/(b)/(e)/(g) and 103(a) apply. Working critical dates: § 102(a)/102(e) → 2010-06-02 (constructive reduction to practice); § 102(b) statutory bar → 2009-06-02.

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2. What I could NOT retrieve — stated plainly

I was unable to obtain the patent's own front-page "(56) References Cited" list (U.S. Patent Documents, Foreign Patent Documents, Other Publications). The authoritative Google Patents full text supplied for this patent renders the front matter but omits the citation tables — the fetched text jumps from "Links" directly to "Classifications," then to the definitions/description. The Justia, FreePatentsOnline, and Patents-Review pages I reached returned only specification/abstract text in their indexed snippets, not the citation block.

Consequently I cannot honestly enumerate "each patent citation for 8867574" with citations and dates, and I will not manufacture a list of U.S. patent numbers to fill that table. That is a data-access gap, not a finding that the patent cites nothing.

What a citation list normally contains for a 2011-filed Qualcomm 802.11ac filing is predictable in shape (11n/11ac preamble patents and IEEE submissions), but shape is not content — verify against the file wrapper before relying on it.

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3. What I did retrieve: the reverse-citation set (patents citing '574)

These are the references that cite US 8,867,574, surfaced in Google Patents / Justia citation tables. Important: these are NOT § 102 prior art. Every one post-dates the '574 priority date (2010-06-02) and therefore can only be relevant as § 102(e) art relative to some other patent, or as evidence of the field's state — never as anticipating art against '574.

Reverse-citation counts of this modest size (a handful of forward cites) are consistent with the earlier finding in this analysis that the patent has never been asserted or IPR'd — it is a portfolio/standards-implementation patent, not a campaign patent.

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4. Most relevant prior art — candidate set, by claim family

The following are the references with the highest genuine § 102/§ 103 exposure, identified from the specification's own admissions and from the contemporaneous TGac/11n record. Each is labeled with my confidence in the citation details. These must be verified against the '574 file wrapper and the primary documents before use in any § 102 chart.

4.1 IEEE 802.11n-2009 / IEEE Std 802.11-2007 — HIGH relevance, HIGH confidence in the document's existence and date

• Citation: IEEE Standard for Information Technology — Telecommunications and information exchange between systems — Local and metropolitan area networks — Specific requirements — Part 11: Wireless LAN MAC and PHY Specifications, IEEE Std 802.11n-2009, approved 2009-10-29.
• Filing/publication date: 2009-10-29 (well before the 2009-06-02 § 102(b) critical date for the L-SIG/HT-SIG/Service elements? — publication is after 2009-06-02, so it is § 102(a)/102(e)-era art and, critically, the 2007 base standard (IEEE Std 802.11-2007, 2007-06-12) predates both).
• Description: Defines the HT preamble (L-STF/L-LTF/L-SIG/HT-SIG/HT-LTF), the HT-SIG signalling field carrying length/MCS, and the 16-bit Service field with 7-bit scrambler seed + reserved bits, plus PHY padding.
• § 102 theory (tentative): The '574 specification itself concedes this lineage — it states the Service field is "two bytes (16 bits)… 7 bits scrambler, 8-bit CRC, leaving one reserved bit," exactly the 11n structure; it describes the GF HT-SIG power-scaling behaviour as "similar to the IEEE 802.11n High Throughput Signal (HT-SIG) field in a Greenfield (GF) packet"; and it proposes "PHY padding as in IEEE 802.11n." That is applicant-admitted prior art usable under § 102(a)/(b) and, more powerfully, as § 103(a) art.
• Claims implicated: Broadly the length-field-per-user and Service-field-format claims (any claim reciting a Service field with scrambler + CRC + reserved-bit partition). Weak-to-moderate as pure § 102 anticipation because 11n has no VHT-SIG-B field; strong as § 103(a) art combined with a VHT-preamble reference.

4.2 IEEE 802.11 TGac contributions by van Nee et al. — HIGHEST subject-matter relevance, citation details UNVERIFIED

• Citation as it appears in the citation trail: IEEE 802.11-09/0633r1, by van Nee et al. I encountered this string in the non-patent-citation record of a later patent in this lineage. I could not verify its title, exact date, or content in this session.
• Likely character: A 2009 IEEE 802.11 TGac (Very High Throughput) submission exploring VHT preamble / VHT-SIG-B design — by the same inventor, in the same window as the '574 provisional.
• Why it matters most: The '574 specification openly frames its core subject matter as "unresolved issues" in the TGac process — number of subcarriers for VHT-SIG-B, pilot mapping, guard interval, and the duration/length field. Statements of that form are an invitation to § 103(a) art from the standards process itself.
• § 102 theory (tentative): Potential anticipation of the subcarrier-count independent claim family (e.g., Claim 1 and its mirror claims) if the contribution discloses a VHT-SIG-B field and a data portion using an equal subcarrier count (56/114/242/484 for 20/40/80/160 MHz).
• Status: CITATION UNVERIFIED. Treat as a lead to pull from the IEEE 802.11 document archive (mentor.ieee.org, DCN 802.11-09/0633), not as established art.

4.3 Contemporaneous Qualcomm sibling filings — relevant, but § 102 problem

• WO 2012/012567 A1 — "Method and apparatus for ordering sub-fields of VHT-SIG-A and VHT-SIG-B fields," Qualcomm; and its U.S. counterpart US 2012/0020261 A1.
• Dates: PCT filed ~2011-07-21 (priority ~2010-07-21); U.S. pub. 2012-01-26.
• Description: Defines size and order of VHT-SIG-B sub-fields (Length, MCS, Tail, reserved bits) and their SU/MU interpretation.
• § 102 theory: Potentially relevant to any claim reciting a VHT-SIG-B field containing a length sub-field, but note the priority-date problem — its 2010-07-21 date is after '574's 2010-06-02 priority, and it is same-assignee art (not "by others"), which limits its § 102(a)/(e) utility. Best used only as § 103(a) background.

4.4 The 802.11ac draft standard itself — HIGH relevance, date-sensitive

• IEEE P802.11ac/D1.0, May 2010 (and later D2.0 etc.).
• § 102 theory: If D1.0 was publicly accessible before 2010-06-02, it is § 102(a)/(b)-era art for the VHT preamble structure. If it post-dates the priority date, it is not prior art at all to '574 (only to later-filed claims). The exact public-availability date of D1.0 relative to 2010-06-02 is the pivot, and I did not verify it here.
• Claim families implicated: the VHT-SIG-B format claims generally, if the draft fixes a subcarrier count and a duration field.

4.5 Art I could NOT responsibly name

I deliberately do not list specific U.S. patent numbers (e.g., 11n-preamble patents by other vendors) as § 102 references, because I could not retrieve them from the '574 citation list and will not substitute plausible-looking numbers. That list must come from the file wrapper.

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5. § 102 mapping summary (tentative, per claim family)

Using the claim families established earlier in this analysis — with the standing caveat that the independent-claim numbers below remain UNVERIFIED (the previously-generated summary flagged that only "on the order of four to eight families" could be confirmed, with independent claims surfacing at 1, 31, 41, 50, 59, 68, 77, 83, 89, 95, 101, 108, 115, 122):

Straight talk on the Family B (bit-repetition) claims: I found no anticipatory reference for the specific "repeat the block N times according to bandwidth" limitation. The pattern (27-bit block ×2 → 54; 29-bit ×4 +1 reserved → 117; 29-bit ×8 +2 reserved → 234) reads as a design choice memo rather than a disclosed structure, which makes it (a) narrow, and (b) hard to anticipate but potentially vulnerable to § 103(a) over 11n/11ac repetition conventions. Do not overstate anticipation here.

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6. What must be done to make this analysis defensible

1. Pull the actual (56) list. USPTO Patent Center / Global Dossier for Application 13/149,411 → "References Cited." That single document supplies the enumeration you asked for and is the only reliable source of the citation set.
2. Pull the IDS and examiner's cited art from the file wrapper — the examiner's "References Cited" and any PTO-892 will show what was actually considered (§ 325(d) implications for any later IPR).
3. Verify IEEE 802.11-09/0633r1 (title, DCN, date) at mentor.ieee.org — this is the highest-value single lead.
4. Fix the 11ac draft public-availability date (D1.0, May 2010) against the 2010-06-02 priority date; this determines whether the draft is prior art at all.
5. Confirm the independent-claim set before mapping any § 102 chart to claim numbers — the numbering used above is explicitly unverified.

Bottom line: I can confirm the patent's identity, its pre-AIA posture, its never-litigated/never-IPR'd status, and its reverse-citation set. I cannot deliver the enumerated front-page citation list with per-reference § 102 mappings, because the citation tables were not retrievable with the tools available and I will not fabricate patent numbers to satisfy the format. The strongest identified prior art is the IEEE 802.11n-2009 / 802.11-2007 standard family (applicant-admitted and dated before the critical date) and the van Nee TGac contribution IEEE 802.11-09/0633r1 (subject-matter-perfect, citation-unverified) — the latter being the reference most likely to bear on the equal-subcarrier-count claims if its contents confirm what its authoring context suggests.

I'll research the prior art landscape for this patent, since the "Prior Art" section results need to be grounded in verifiable references.

Let me verify the key reference details before building the §103 analysis.

Obviousness Analysis — U.S. Patent No. 8,867,574 under 35 U.S.C. § 103

⚠️ Scope flag (contradiction in the record provided)

The task instructs me to "use the results from the Prior Art section of this page." No Prior Art section was included in the sections handed to me. The previously generated sections cover: patent summary, litigation, PTAB challenges, strategic summary, and assignment history — none contains a prior-art list. Rather than silently invent one, I reconstructed the prior-art universe from (a) the face-cited references and ISR of US 8,867,574 itself, (b) the cited-reference lists of examiner-curated US patents in the same field, and (c) the publicly retrievable TGac (IEEE 802.11ac) document record. Every reference below is tagged [VERIFIED] (I retrieved its existence/date) or [UNVERIFIED — title/date only] where I could not pull full text. Where a reference's content is asserted, I say so explicitly.

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1. Governing law and the critical-date problem (this is the whole ballgame)

The patent was filed May 31, 2011 with a provisional (61/350,817) filed June 2, 2010. It is therefore pre-AIA § 103, and the prior-art window has two possible critical dates:

Practical implication: the single most valuable prior-art asset — the May 17–20, 2010 IEEE 802.11 TGac submissions — is only a statutory bar under Scenario 2. Under Scenario 1 it is § 102(a) art that Qualcomm can attack with a § 1.131-type prior-invention showing (the inventors Van Nee and Van Zelst were themselves active TGac contributors in 2009–2010, so corroborated conception evidence plausibly exists). Any § 103 ground built on the May 2010 documents must be paired with a § 112/priority challenge, or with a § 102(b)-eligible anchor reference (IEEE P802.11n/D9.0).

Two further traps:

• Inventor-authored references. TGac doc 11‑10/0578r1 "Preamble Parameters" (van Nee et al., May 17, 2010) is authored by a named inventor. Under pre‑AIA law it is not "by others" and cannot be § 102(a) art. The same applies to 11‑10/0876r0 "802.11ac Preamble" (Sampath et al., Jul 13, 2010), 11‑10/1052r0 "VHT‑SIG‑A and VHT‑SIG‑B Field Structure" (van Nee et al., Sep 9, 2010), and the Nov 2, 2010 "VHT‑SIG‑B in NDPs" presentation (van Zelst) — all post-date the priority date anyway, so they are not prior art at all. Do not cite them as § 102 art.
• The 802.11ac standard itself is not prior art. Draft 0.1 (Jan 2011) and everything after post-date the priority date. Its utility is evidentiary (what a POSITA expected), not § 102.

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2. Person of ordinary skill in the art (POSITA)

A B.S. in EE or CS (or equivalent) plus 3–5 years of experience in OFDM WLAN PHY design, including familiarity with the IEEE 802.11a/n MAC/PHY, the 802.11n HT-SIG/HT-LTF structures, OFDM subcarrier/pilot mapping, convolutional coding with tail bits, and familiarity with the TGac (802.11ac) proposal record as of mid-2010. This is corroborated by the breadth of non-patent literature the Examiner and the art treat as background (Draft 802.11n D9.0, Broadcom/Zhang preamble submissions).

3. The claim families to be analyzed

Per the previously generated analysis (independent-claim numbers unverified), the asserted subject matter reduces to:

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4. Prior-art library

Two documentary facts worth quoting because they are applicant admissions in the '574 specification itself:

1. "At least two options are available for electing the number of subcarriers for the VHT-SIG-B field. … the number of subcarriers may be equal to that of the VHT-SIG-A field, while for other aspects, the number subcarriers may be equal to the number of subcarriers used for the VHT data portion." — a textbook "finite number of identified, predictable solutions" admission (KSR).
2. "This may be similar to the IEEE 802.11n High Throughput Signal (HT-SIG) field in a Greenfield (GF) packet" — made in the very passage describing power scaling so that total power is kept equal while per-tone power differs. That is an admission that Family A′'s power arrangement already existed in 802.11n GF.

Also note the specification's framing that "several unresolved issues remain" (subcarrier count, pilot mapping, guard interval, duration field) — i.e., the patentee concedes these were open design questions being worked in the art, which is simultaneously a motivation-to-improve admission and a simultaneous-invention signal.

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5. Ground 1 — § 103: Claims of Family A (field/data same number of subcarriers)

Primary: IEEE P802.11n/D9.0. Secondary: 11‑10/0627r00; 11‑10/0358r1; US 2010/0260159 A1.

Rationale for the combination (KSR):

• Known technique, predictable result. D9.0 already taught a second, VHT-style SIG field carrying a length value, carried in the same OFDM symbol grid as data. Extending that grid to the VHT-SIG‑B symbol is application of a known technique to a known device.
• Design need. Legacy coexistence requires L‑SIG to signal duration while the VHT-specific field carries the useful data length; 11‑10/0627r00 ("Why we need Length Field in VHT SIG") supplies the articulated need.
• Only two solutions existed. The patent itself says there were two options (match SIG‑A, or match data). Picking one of two identified solutions is the paradigm of KSR's "obvious to try."
• Design incentive to match data. Matching the data numerology lets the receiver reuse the same FFT/equalizer/pilot-tracking hardware and lets pilot mapping be shared — an engineering-efficiency motivation a POSITA would immediately recognize (and which the patent itself asserts as the benefit).

Weakness to flag: under Scenario 1, two of the three best secondary references (0627r00, 0358r1) are § 102(a)-only, and their content is [UNVERIFIED] by me. A petitioner must retrieve the actual decks and confirm they disclose the length-in-VHT-SIG‑B concept. An independent third-party corroboration exists in the public record — a Korean TTA report credits ETRI with proposing that "VHT‑SIG‑B에는 사용자별 데이터 길이를 명시" (per-user data length in VHT‑SIG‑B) — but I could not date that proposal, so it is a lead, not a citation.

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6. Ground 2 — § 103: Family A′ (total power equal / per-tone power differs)

Primary: IEEE P802.11n/D9.0 (HT‑SIG in Greenfield). Secondary: the '574 specification's own admission.

The power-scaling limitation is arguably the weakest of the families because the patent's own text concedes the concept: in describing the "match VHT-SIG‑A subcarriers" option, the specification states that "power scaling may be applied to keep the VHT-SIG-B total power equal to the VHT-LTF total power," while "the per-tone power of the VHT-SIG-B field may be different," and then says "[t]his may be similar to the IEEE 802.11n HT-SIG field in a Greenfield (GF) packet."

That sentence is an admission that the claimed power relationship was known in the 802.11n Greenfield packet, which is § 102(b) art (D9.0, Mar 2009). Combined with D9.0's explicit HT‑SIG/HT‑LTF power normalization, the limitation is met or rendered obvious; the motivation (avoid AGC/decoder scaling surprises by keeping symbol energy constant when tone counts differ) is self-evident and is stated in the reference itself.

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7. Ground 3 — § 103: Family B (bandwidth-dependent bit-block repetition)

Primary: IEEE P802.11n/D9.0 (40 MHz duplication of legacy/HT‑SIG). Secondary: the '574 specification's admission that VHT-SIG‑A subcarriers are "#duplicated just like the VHT-SIG-A field"; R&S 1MA192 Table 1/§ 4.3; 11‑10/0064r5 (VHT Frame Padding); 11‑10/0821r0 (VHT Packet Length Calculation).

Element mapping:

• Determine channel bandwidth → inherent in a multi-bandwidth (20/40/80/160 MHz) PHY, taught by D9.0 (20/40) and the 11ac framework (80/160).
• Generate a block of bits based on the bandwidth → D9.0's bandwidth-dependent SIG/bit structures (HT-SIG length field width and 40 MHz SIGNAL structures).
• Repeat the block a number of times according to the bandwidth → duplication of SIG content across 20 MHz subchannels was already the 802.11n practice for 40 MHz, and the '574 specification itself says the alternative design duplicated VHT-SIG‑A subcarriers "just like the VHT-SIG-A field." R&S § 4.3 states the system-wide rule that "VHT will send the same preamble in each 20 MHz sub band," and the Korean survey literature describes VHT‑SIG‑B being "repeated for each 20 MHz" of the used bandwidth.
• Receive side: "a plurality of replicated blocks … bits of one block repeated in each block" → directly anticipated in kind by that duplication practice; the receive-side benefit (combining repeated soft values) is the ordinary diversity-combining technique a POSITA would apply.

Motivation: (i) the VHT‑SIG‑B payload (26 bits at 20 MHz) does not scale with bandwidth, so the same information must be spread over 2×/4×/8× the tones to fill the OFDM symbol — the patent's own stated reason; (ii) frequency duplication was already the 11n/11ac mechanism for legacy coexistence; (iii) repetition yields processing gain by averaging repeated soft values, a predictable, well-known benefit the patent itself asserts. Under KSR this is "use of a known technique to improve a similar device in the same way," not invention.

Note the reference to US 9,143,300 (whose claim 4 recites that "VHT‑SIG A1, VHT‑SIG A2, VHT‑SIG B and the data fields repeat their respective previous symbols through a repetition scheme") — a third-party patent in the same field treating SIG-field repetition as the known state of the art. Heavily caveated: I did not verify its priority date, so it is evidence of industry understanding at best.

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8. Ground 4 — § 103: the dependent limitations

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9. Overall motivation-to-combine narrative (satisfying KSR/MPEP 2143)

A petition should lead with these five rationales, each anchored in a reference:

1. Design need / market pressure — the TGac PAR goal of ≥1 Gbps in ≤80 MHz forced every 20 MHz of bandwidth to carry VHT SIG information; the same SIG‑B payload therefore had to be duplicated across bonded subchannels.
2. Articulated problem in the art — 11‑10/0627r00 and 11‑10/0358r1 expressly identify the need for a (per-user) length indication in the VHT SIG, and the '574 specification concedes the issue was "unresolved."
3. Finite number of identified solutions — the patent admits exactly two subcarrier options and a small menu of Service-field/length-field arrangements. KSR: predictable solutions ⇒ obvious.
4. Known technique, predictable result — 11n already duplicated SIG fields across 20 MHz subchannels for 40 MHz, and 11n GF already normalized SIG total power against LTF power while allowing different per-tone power.
5. Predictable, asserted benefit — repetition averaged at the decoder yields processing gain; the patent claims that benefit but does not teach anything beyond the routine averaging.

Also worth pleading: simultaneous, multi-vendor activity — the 11ac SIG‑B design was being reduced to practice concurrently by Broadcom/Zhang, Samsung/Kim, ETRI, NTT/Morioka, LG/Park, and others in 2009–2010. Documented simultaneous invention of the same solution is recognized evidence of ordinary skill (KSR; Cellophane).

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10. Where the § 103 case is weak, and counterarguments to expect

• Priority/antedating risk. As set out in § 1, the strongest 11ac-specific references (the May 2010 TGac decks) may be § 102(a)-only, or may even be disqualified as inventor-authored. Build the ground on D9.0 plus Nov 2009–Jan 2010 third-party contributions, and treat the May 2010 material as reinforcement.
• § 325(d). The '574 was prosecuted with IEEE P802.11n/D9.0 and Zhang & Erceg "Preamble Discussions" already of record. A petition must show the Examiner never considered the specific TGac documents relied on (they are absent from the face-cited list I could retrieve).
• Secondary considerations with potential nexus. The adopted 802.11ac VHT-SIG‑B format closely resembles the claimed formats; Qualcomm will argue industry adoption/praise and copying. Rebut with (a) the standard was the consensus of a multi-vendor committee, which cuts toward obviousness, and (b) no failure-of-others or blocking-patent evidence appears in the record.
• The bit-block architecture (the exact 27‑ and 29‑bit partitions with reserved bits in specific positions, and the "at least 232 bits" floor) is the narrowest and most defensible part of the claim set. A § 103 attack here needs an express reference showing the reserved-bit placement; absent that, expect a non-obviousness argument about the specific block boundaries — though the boundaries are largely forced arithmetic (20 info + n reserved + 6 tail) once the tone count is fixed.
• § 112 exposure is real but separate: the 116-vs-126 discrepancy noted above, and whether the June 2, 2010 provisional actually supports the "same number of subcarriers" and repetition claims, are worth developing as parallel invalidity theories — and they also determine which critical date applies.

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11. Verification checklist (do this before filing)

1. Retrieve full text of the TGac documents so that every "content" assertion above is replaced with a pin cite: 11‑10/0358r1, 11‑10/0382r0–r2, 11‑10/0534, 11‑10/0549r2, 11‑10/0627r00, 11‑10/0064r5, 11‑10/0070r0, 11‑09/1174r0, 11‑09/1258r0, 11‑09/0992 (which revision?) — all via the IEEE 802.11 document archive at https://mentor.ieee.org/802.11/dcn. Confirm public accessibility dates (printed-publication status).
2. Confirm the filing dates and § 102(e) status of US 2010/0260159 A1 and US 8,238,316 B2 (and identify the '316 assignee).
3. Obtain the prosecution history of 13/149,411 to determine (a) whether the claims are supported by provisional 61/350,817 (fixing the critical date) and (b) exactly which references the Examiner considered (§ 325(d)).
4. Resolve the 116-vs-126 discrepancy between the granted claims and the pre-grant publication (claim 88 of US 2011/0299468).
5. Confirm the granted independent-claim numbering — the previously generated section flags claims 1, 31, 41, 50, 59, 68, 77, 83, 89, 95, 101, 108, 115, 122 as unverified.
6. Primary source for the patent itself: patents.google.com/patent/US8867574B2/en; claim listing at patents.justia.com/patent/8867574.

Bottom line: the '574 claims sit in the middle of an intensely documented, multi-party design debate in which the patentee's own specification concedes the prior-art analog (11n Greenfield HT‑SIG), concedes that only a handful of options existed, and concedes that duplication of SIG content across 20 MHz subchannels was the existing practice. A § 103 case is substantively strong — provided the petitioner chooses references that survive the antedating problem, which is the decisive issue, not the technical merits.