US 6611509

I'll verify the litigation/assignment posture with targeted searches, then summarize.

Let me try to pull the exact claim language, since the fetched text omitted the claims section.

Search scope and what it returned

I searched for the literal string 6611509 / US6611509 across Google Patents, Justia Patents, patent-family annexes, PTAB/IPR exhibit filings, NPE litigation databases, and Federal Circuit materials surfaced in those searches. Results:

• USPTO/Google Patents record for US 6,611,509 B1 — retrieved and used as the authoritative text (full specification, abstract, classifications, assignment chain, legal status).
• Claims text — retrieved from Justia's mirror of the patent (https://patents.justia.com/patent/6611509), which reproduces claims 1–4 (truncated thereafter).
• CAFC 2026 dockets — No docket, briefing, or opinion specifically involving US 6,611,509 was found. I explicitly decline to report any. Note that the patent's own record shows an anticipated expiration of 2019-03-09, so a 2026 appeal on the '509 patent would be unlikely. The INVT SPE LLC Federal Circuit activity surfaced in search (e.g., INVT SPE LLC v. ITC, ITC Inv. No. 337-TA-1138) concerns other patents in the same corporate portfolio — notably U.S. 7,269,439 and 6,760,590 — not 6,611,509. I flag that as a possible source of confusion and have not merged those results into this summary.
• Same-family but different numbers (do not conflate): US 6,807,162 B2, US 6,973,065 B2, US 7,778,224 B2, and application US 10/166,268 all claim priority to the '509 application but are different patents with different claims. Their claim text is not the '509 claim text.

US 6,611,509 B1 — bibliographic data

Abstract (as issued)

Control section 125 at base station 100 in a CDMA/TDD mobile communication system assigns one or more fixed forward link time slots to a plurality of time slots divided at a communication frame at a predetermined interval, and forward link time slots and reverse link time slots to the time slots except for the fixed forward link time slots by allocating corresponding to a ratio of a total information volume of a forward link to a total information volume of a reverse link in the system, in order to transmit a control channel signal including a synchronization control channel signal using the fixed forward link time slots, and to transmit forward link and reverse link traffic channel signals using the forward link time slots and the reverse link time slots that are allocated according to the number of time slots respectively required corresponding to the respective information volume.

Independent claim — plain-language overview

Claim 1 (the only independent claim I could verify) is drafted as a base station apparatus claim in a CDMA/TDD communication system using a frame divided into a plurality of slots, each assigned to either the forward link or the reverse link. It requires two elements:

1. An assignor that assigns a forward link common control channel to position-fixed time slots disposed at regular intervals among the frame's slots. In plain terms: the sync/common control channel is pinned to a repeating, evenly spaced slot pattern that does not move even when the up/down split changes.
2. A controller that assigns a forward link user information channel and a reverse link user information channel to the remaining slots (those other than the position-fixed ones), in accordance with a ratio of the forward-link information volume to the reverse-link information volume. In plain terms: after the sync slots are reserved, the residual slots are divided between downlink and uplink traffic proportionally to how much data each direction needs — so the frame can flex between downlink-heavy and uplink-heavy while the sync grid stays fixed.

The technical payoff described in the specification (col. describing the first embodiment): because the sync control channel always lands on the same periodic grid, a mobile station powering on does not need to know the current forward/reverse split — it can integrate correlation values over the known slot period and acquire synchronization quickly; and because a forward-link common control channel slot always sits immediately before a reverse-link slot, a measured reception quality is at most ~2 slots old, keeping open-loop transmit power control accurate under fading. The specification frames the invention against the prior art problem that "when an assignment of time slots to forward link and reverse link is changed corresponding to information volume … a configuration of the synchronization control channel becomes irregular … it thereby takes a longer time for a mobile station to acquire synchronization."

Dependent claims I could verify (verbatim substance)

• Claim 2 — the forward link common control channel comprises a synchronization control channel.
• Claim 3 — the position-fixed slots are disposed at regular intervals of every second time slot.
• Claim 4 — the position-fixed slots are disposed at regular intervals of every fourth time slot.

The corresponding specification embodiments disclose the same scheme at every two, every four, every eight, and every sixteen slots (FIGS. 3–6), plus a two-slot variant in FIG. 4. It is therefore reasonable to expect further dependent claims covering the eight-slot (and possibly sixteen-slot) intervals, and possibly one or more additional independent claims (e.g., a system-level or synchronization-acquiring-method claim — the divisional US 6,807,162 contains a mobile-station-apparatus claim and a synchronization-acquiring-method claim).

Explicit uncertainties

1. Full claim set not verified. I have verbatim text only for claims 1–4. I do not know the total claim count of the '509 patent, and I have not verified whether additional independent claims exist. Do not treat claims 5+ as characterized here.
2. No CAFC 2026 docket. I found no evidence of any 2026 Federal Circuit proceeding involving US 6,611,509. Any assertion to the contrary should be treated as unverified. The apparent source of confusion is the INVT SPE portfolio's other patents.
3. Litigation history not confirmed for '509 specifically. INVT SPE LLC filed a family of D.N.J. suits (e.g., 2:17-cv-03738 against Apple; 2:17-cv-06522 against ZTE; 2:17-cv-03740 against HTC) and participated in ITC Inv. No. 337-TA-1138. Search results tied those matters to patents such as 6,760,590 and 7,269,439. I did not verify that 6,611,509 was itself asserted in any of them, and the '509 patent expired in 2019 in any event.
4. Typographical artifacts in the source. The Google Patents text contains several apparent OCR/transcription errors ("a total information volume of a forward link Lo a total information volume of a reverse link"; several "(D) in FIG. 3" / "(B) in FIG. 4" figure cross-references that point to the wrong figure; a claim-reference to "control section 125" inside the mobile-station discussion). Per the strict rule, I have reproduced identifiers literally rather than silently correcting them.

Sources: https://patents.google.com/patent/US6611509/en (full specification, abstract, assignment/status data); https://patents.justia.com/patent/6611509 (claim text, claims 1–4); Google Patents family/priority links for US 6,807,162, US 6,973,065, US 7,778,224; Korean IPO International Search Report for PCT/KR2008/004837 (cites US 6,611,509 as prior art and lists its family); Inventergy proxy statement inventory list (ir.inventergy.com, accession 0001144204-16-141762).

I'll research litigation involving US Patent 6,611,509. Let me run several targeted searches.

Key context found — but several hits are for different patents with the same "509" suffix (e.g., U.S. 11,019,509 in the Constellation/LG case; a Microlog '509). Let me pin down cases involving the specific patent 6,611,509.

Bottom line

I could not verify any litigation that specifically asserts U.S. Patent No. 6,611,509 ("CDMA/TDD mobile communication system and method," Matsushita/Panasonic → Inventergy → INVT SPE LLC). Every "509" case I turned up in litigation databases involves a different patent whose number happens to end in 509. Given your instruction not to auto-correct or blend identifiers, I am reporting the "no verified case" finding rather than attributing other parties' '509 litigations to this patent.

One important timing fact from the record you supplied: the Google Patents legal status for 6,611,509 shows "2019-03-09 Anticipated expiration" (priority 1998-03-10; filed 1999-03-09). Any assertion window for this patent would therefore have to fall in roughly 2014–2019, which is consistent with the ownership history in your record (Panasonic → Inventergy, Jan 2014 → INVT SPE LLC, June 2017).

Closest matching campaign — INVT SPE LLC (verified as to the campaign, NOT verified as to this patent)

The same current assignee listed on your page (INVT SPE LLC) ran a Panasonic-origin cellular patent campaign in 2017–2022. The public record identifies these matters:

Critically, the patents the ITC record names as asserted in 337-TA-1138 are the '949, '439, '590, '587 and '711 patents — with U.S. Patent Nos. 7,206,587 and 7,764,711 expressly identified, and claims 3–4 of the '590 patent, claim 4 of the '587 patent, and claims 1–2 of the '439 patent as the claims that remained in the investigation. No "6,611,509" (which would be cited as the '509 patent) appears on that list. Because the D.N.J. cases were stayed pending the ITC matter, the asserted patents in those suits very likely overlapped the ITC set — but I could not retrieve the district-court complaints to confirm whether 6,611,509 itself was ever pleaded, so treat that as unverified.

Related proceeding noted but not attributed: IPR2018-01476, Apple Inc. v. INVT SPE LLC (PTAB) — the file includes ITC Exhibit 2001 from 337-TA-1138; I could not confirm which patent number was challenged, and I have no evidence it was 6,611,509.

Deceptive look-alikes (explicitly NOT this patent)

These are the results that dominate searches for "6611509" / "'509 patent," and each is a different patent:

• U.S. Patent No. 11,019,509 — Constellation Designs, LLC v. LG Electronics, Inc., et al., No. 2:21-cv-00448-JRG (E.D. Tex.) (filed Dec. 9, 2021). Jury verdict July 11, 2023 (infringement of claims 21, 23 of the '509 patent; not invalid; willful; $1,684,469 running royalty); Final Judgment Aug. 22, 2023; JMOL of obviousness and of no damages denied April 23, 2024; on appeal to the Federal Circuit.
• ICU Medical, Inc. v. Alaris Medical Systems — a medical-valve '509 patent, unrelated.
• Microlog Corp. v. Cisco Systems, Inc., et al. — asserted a software '509 patent (Cisco, Aspect Software, RightNow, Moxie, Contact Solutions).
• LG Electronics v. Bizcom Electronics — an image-processing-system '509 patent.
• A PubMed reference list and multiple TTAB filings matched only the digit string "6611509"; not patent litigation.

What I could not do, and suggested verification paths

I was unable to pull the litigation/"Similar" data panel from the Google Patents page itself, and searches of Unified Patents' litigation portal, CourtListener/RECAP and PACER indexes returned no docket in which 6,611,509 is the asserted patent number. To confirm or disprove before relying on this:

1. USPTO Patent Center / Assignment records for 6,611,509 (reel/frame for the INVT SPE assignment) and Patent Center's "Litigation" tab.
2. PACER dockets: D.N.J. 2:17-cv-07458/07459/07460, and the D. Del. predecessor complaints (Feb. 2017), checking the "Asserted Patents" paragraphs directly.
3. ITC EDIS, Inv. No. 337-TA-1138, for the original complaint (Sept. 14, 2018) and the 83 FR 53106 notice of investigation, to see the complete patent list.
4. Unified Patents / RPX Docket Navigator / Lex Machina filtered by patent number, not by party.

If you want, I can attempt another pass specifically targeting the D.N.J. complaints and the ITC complaint exhibit list to determine whether 6,611,509 was ever pleaded.

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

Proceedings overview

Total AIA trial proceedings on US 6,611,509: 0. Breakdown: 0 active, 0 with claims invalidated, 0 with claims sustained, 0 settled, 0 institution-denied — the USPTO Open Data Portal returns no IPR, PGR, or CBM proceeding for this patent, and targeted web searches for a proceeding number tied to 6,611,509 surfaced none.

Bottom-line defensive posture: the opposite of "hardened by IPR." No challenger has ever put these claims in front of the Board, so no claim of 6,611,509 has ever been tested, canceled, or sustained — the patent is untested, not validated. More importantly for a defendant today, the structured record shows the patent is Expired – Lifetime, with an anticipated expiration of 2019-03-09 (application filed 1999-03-09; term counted from that filing). Combined with the 35 U.S.C. § 286 six-year damages lookback from today (2026-09-30), a complaint filed now reaches back only to 2020-09-30 — entirely after expiry. The practical exposure on a straight assertion of the '509 patent is therefore near-nil, and the absence of any PTAB paper trail means you also have no petitioner estoppel or Board claim constructions to leverage or work around. If a demand letter cites 6,611,509, the first question is not "which claims are dead" but "what are the recoverable pre-expiration acts, if any."

No PTAB proceedings exist for US 6,611,509

There is no proceeding entry to report. Rather than invent one, here is exactly what I verified and what I did not:

• The authoritative source in this prompt ("PTAB proceedings on file") is the USPTO ODP structured feed, which contains no AIA trial for this patent. That is the canonical list per the operating rules, and I treat it as controlling.
• Web searches for a proceeding number paired with 6,611,509, and for the patent owner chain (Matsushita → Panasonic → InVentergy → INVT SPE LLC), returned no IPR/PGR/CBM petition naming 6,611,509.
• I cannot rule out an ex parte reexamination or a pre-AIA inter partes reexamination on this patent — those are outside the ODP AIA-trial block and outside my scope here. Flagging as unverified rather than asserting a negative.

Adjacent proceedings on sibling patents — not this patent, but relevant to the owner's posture.
The patent's ultimate owner, INVT SPE LLC (Fortress-managed), ran a 2017–2022 assertion campaign using seven different former Panasonic patents — U.S. 6,466,563; 6,611,676; 6,760,590; 7,206,587; 7,760,815; 7,764,711; and 7,848,439. 6,611,509 was not among them. That campaign did attract IPRs from Apple, HTC, and ZTE (USA) against the sibling patents:

• IPR2018-01473, Apple Inc., HTC Corp., HTC America, Inc., and ZTE (USA) Inc. v. INVT SPE LLC — U.S. 6,611,676 (Miyoshi et al., not the Hayashi et al. '509 patent). Panel: APJs Thu A. Dang, Kevin F. Turner, Barbara A. Benoit. Final Written Decision 2020-03-25 holding that Petitioner had not shown claims 1–3, 5–9, and 11 unpatentable; claims 4 and 10 were statutorily disclaimed by the patent owner during trial and not addressed. FWD text
• IPR2018-01474, Apple Inc. v. INVT SPE LLC — institution denied (2019-03-05); Docket Alarm lists inventors Kenichi Miyoshi, Osamu Kato, Junichi Aizawa, matching the '676 patent, not the '509 patent. Panel: Benoit, Turner, Dang. Docket
• IPR2018-01478, Apple Inc. and ZTE (USA) Inc. v. INVT SPE LLC — U.S. 6,760,590; institution denied (2019-02-19). Order on conduct at docket link (IPR2018-01477 is referenced as a concurrent proceeding on another sibling).
• The related Federal Circuit decision INVT SPE LLC v. ITC, 46 F.4th 1361 (Fed. Cir. 2022) (No. 20-1903, decided 2022-08-31) affirmed no § 337 violation as to the '439 patent on non-infringement and vacated the '590 ruling as moot on expiration. Opinion PDF

The takeaway from the adjacent record: the Fortress/INVT team did assert aggressively and did draw IPRs — just never on 6,611,509. That is consistent with the '509 patent being a residual, lower-value asset in the 740-patent tranche rather than a litigated one.

Strategic summary

Claim status. No claim of 6,611,509 has been canceled, narrowed, or confirmed by the PTAB, because no claim was ever challenged there. Every claim — including claim 1, the control-section/fixed-forward-link-time-slot claim recited in the abstract, and its dependents through the terminal claim (the structured text shows a fourth-embodiment family of 16-slot/15-slot allocations but the fetched description truncates before the full claim set; I did not obtain the complete claim list and will not guess at individual claim numbers) — is UNTESTED. The only claim-level narrowing of record is the ordinary prosecution history, not an IPR outcome. Practically, the claims are dead only in the economic sense: the patent expired on/about 2019-03-09 per the ODP legal-status line ("Expired – Lifetime"). Treat 2019-03-09 as the operative date with the caveat that any § 154(b) patent term adjustment could push actual expiry modestly later — I do not have the face-of-patent PTA figure, so verify against the printed patent before relying on the exact date.

Estoppel landscape. Because there is no Final Written Decision on this patent, no § 315(e)(2) estoppel binds anyone. Any defendant is free to raise every § 102/§ 103/§ 112 ground, every reference, and every combination — nothing is foreclosed as "raised or reasonably could have been raised." The flip side: the patent owner is also unconstrained, and you get no free benefit from a prior petitioner's expert testimony, claim construction record, or the Board's obviousness analysis. There is no prior-art roadmap to inherit. If you needed to invalidate the claims (for example, to knock out a pre-2019 damages theory or a license that survives expiry as to back royalties), you would be building from zero — but note that this is also an ordinary district-court invalidity case, not an IPR, if the patent has already expired and no live Board vehicle is attractive.

Pattern signals. No repeat petitioner, because there is no petitioner at all. No patent-owner PTAB appeal on this patent. No defensive aggregator (Unified Patents or similar) is in the chain — the only entities that appear are Matsushita/Panasonic, InVentergy Global, and Fortress-controlled INVT SPE LLC (current assignee of record). The ITC and CAFC activity is real but is on the sibling Panasonic patents, and the CAFC's capability-vs.-operation holding in INVT SPE v. ITC would be highly unfavorable to any attempt to plead 6,611,509 infringement by standard-compliance alone — that reasoning is portable even though the '509 claims weren't at issue. Also note the owner's own campaign has collapsed: per RPX reporting, the Apple and ZTE district court cases were dismissed with prejudice (2021-06 and 2022-05), and only the HTC New Jersey case remained active, in settlement discussions. CBM is not an option and never was — CBM review sunset on 2020-09-16, and a 1998-priority wireless duplexing patent is not a "covered business method" patent in any event.

Recommended next steps

• If you are a defendant on a fresh assertion: confirm the expiration date from the printed patent's term-adjustment notice, then run § 286 math. With a 2026 filing date and a ~2019 expiry, recoverable damages should be zero unless the plaintiff can tie you to pre-expiration conduct already preserved by an earlier complaint or a license accrual. That is a Rule 12 or summary-judgment posture, not an IPR posture.
• If an earlier complaint or ongoing litigation predates expiry: pull the ITC/CAFC record for the capability holding in INVT SPE LLC v. ITC, No. 20-1903 (Fed. Cir. 2022-08-31). It is the strongest available non-infringement template for a standard-compliance theory against this family, and it is binding precedent.
• No active proceedings means no trial calendar to track. There is no institution deadline, no oral hearing, and no statutory one-year FWD clock to monitor for this patent. The absence is itself a signal here — but read it correctly: the reason is non-assertion plus expiration, not "the patent survived scrutiny." Do not let opposing counsel characterize the clean PTAB docket as validation.
• Check the family, not just this patent. The structured ODP record shows the same priority chain continuing into U.S. 6,807,162, U.S. 6,973,065, and U.S. 7,778,224, all claiming priority to the 1998-03-10/1999-03-09 family. Those are separate assets with their own PTAB and term histories; I did not verify their status here and am not assuming they expired on the same date. If the demand letter is portfolio-wide, pull each one's ODP PTAB block and expiration separately before conceding anything.

I'll start by gathering assignment and litigation records from multiple sources.

Now let me search for the specific assignment records, reel/frame numbers, and any litigation asserting this patent.

Let me dig for reel/frame specifics, litigation on this exact patent, and inventor history.

US 6,611,509 B1 — Ownership Chain Reconstruction

Data-access caveat up front (please read before relying on any figure below): I have the authoritative patent text and its Google Patents legal-events block, plus RPX/SEC/Unified Patents/Stanford NPE-database reporting. I was not able to retrieve the USPTO Assignment Center's reel/frame numbers or the correspondent-of-record fields for this patent from the sources reachable to me (the Assignment Center itself is a session-driven query interface that my search tooling could not query directly). Rather than fabricate reel/frame numbers or attorney names, I mark those fields NOT RETRIEVED — verify directly. Nothing below is invented; every date is sourced to the Google Patents legal-events block (which mirrors USPTO assignment records) or to cited public reporting.

Inventors

All four are named on the original ASSIGNMENT OF ASSIGNORS' INTEREST to Matsushita Electric Industrial Co., Ltd., recorded 1999-03-09 (per the Google Patents legal-events block; reel/frame not retrieved).

Unusual patterns: None evident. This is an ordinary employer-assignment case — a corporate R&D team assigning to its employer on the filing date. I found no evidence that any inventor departed Matsushita/Panasonic within 12 months of filing, and no evidence of inventor-held or inventor-retained rights. I note explicitly: absence of evidence here is not proof of absence, since I could not run employment-history checks. The "inventors leave before the fire-sale" tell does not apply to this chain — the 2013–2014 transfer was a corporate portfolio divestiture by Panasonic, not a founder/inventor-driven sale.

Family note: the same application spawned continuations later issued as US 6,807,162, US 6,973,065, and US 7,778,224 (Google Patents priority links, 2002-06-11 / 2003-04-22 / 2004-07-08). Those siblings travel the same ownership chain and are worth pulling as a group at the Assignment Center.

Original assignee

Matsushita Electric Industrial Co., Ltd., Osaka, Japan — named on the 2003-08-26 grant. Renamed Panasonic Corporation effective 2008-10-01 (change-of-name recorded 2008-11-20 per the Google Patents legal events).

• Line of business: Consumer electronics and, relevantly, mobile communications infrastructure and handsets, plus a 3GPP standards participant (the patent itself is framed around CDMA/TDD slot assignment and synchronization-channel design).
• Did they ship a product embodying the claims? Unclear / not established. Panasonic was demonstrably an operating manufacturer and standards participant in W-CDMA/CDMA-TDD. However, I could not verify a specific commercial base-station or handset product practicing the claimed fixed-slot synchronization-control-channel scheme, and the patent's own framing is that conventional CDMA/TDD slot assignment produced irregular sync-channel configurations — i.e., the claims read on an improvement, not necessarily on shipped product. I will not assert embodiment.
• Current status: Operating. Matsushita → Panasonic Corporation → now part of Panasonic Holdings Corporation (reorganized 2022). Not dissolved, not bankrupt.

Why the original assignee left the chain: On/around 2013-12-20, Panasonic executed a Patent Purchase Agreement (effective 2013-10-21) selling ~500 patent assets to Inventergy, Inc. (the agreement and its 2015-12-31 amendment are public via Inventergy's SEC filings and Law Insider). Consideration was an up-front payment plus a net-revenue share to Panasonic, with a grant-back license to Panasonic and Panasonic retainer of royalty-collection rights. The press release was issued 2014-01-06 (Inventergy 8-K, accession 0001144204-14-001009).

Assignment timeline

Chronological, from the Google Patents legal-events block for US 6,611,509 (mirroring USPTO recordings). Reel/frame and correspondent fields are NOT RETRIEVED — I could not query the Assignment Center's field-level data; they must be pulled manually.

• 1999-03-09 (executed, same day as filing) / recorded 1999-03-09 — Reel NOT RETRIEVED

  • Conveyance: Assignment of Assignors' Interest
  • Assignor: Masaki Hayashi; Kazuyuki Miya; Toyoki Ue; Katsuhiko Hiramatsu
  • Assignee: Matsushita Electric Industrial Co., Ltd.
  • Correspondent: NOT RETRIEVED
  • Context: Ordinary inventor-to-employer assignment on filing.

• 2008-10-01 (executed) / recorded 2008-11-20 — Reel NOT RETRIEVED

  • Conveyance: Change of Name (see Google Patents entry: "CHANGE OF NAME (SEE DOCUMENT FOR DETAILS)")
  • Assignor: Matsushita Electric Industrial Co., Ltd.
  • Assignee: Panasonic Corporation
  • Correspondent: NOT RETRIEVED
  • Context: Internal corporate renaming only — no change in beneficial ownership.

• 2013-12-20 (executed; PPA effective 2013-10-21) / recorded 2014-01-03 — Reel NOT RETRIEVED

  • Conveyance: Assignment of Assignors' Interest
  • Assignor: Panasonic Corporation
  • Assignee: Inventergy, Inc. (later Inventergy Global, Inc., NASDAQ: INVT)
  • Correspondent: NOT RETRIEVED
  • Context: Portfolio divestiture / de facto privateering — ~500 Panasonic 3G/4G assets sold to a public licensing-only NPE with revenue share and grant-back to Panasonic. This is the pivotal link in the chain.

• 2014-01-27 (executed) / recorded 2014-01-27 — Reel NOT RETRIEVED

  • Conveyance: Security Agreement
  • Assignor: Inventergy, Inc.
  • Assignee: Joseph Beyers
  • Correspondent: NOT RETRIEVED
  • Context: Securitization — insider/creditor collateral filing.

• 2014-01-29 (executed) / recorded 2014-01-29 — Reel NOT RETRIEVED

  • Conveyance: Security Agreement
  • Assignor: Inventergy, Inc.
  • Assignee: Hudson Bay IP Opportunities Master Fund, LP, as Collateral Agent
  • Correspondent: NOT RETRIEVED
  • Context: Securitization — debt financing collateralized by the portfolio.

• 2014-03-25 (executed) / recorded 2014-03-25 — Reel NOT RETRIEVED

  • Conveyance: Release by Secured Party (as to the Beyers security interest)
  • Assignor: Joseph Beyers
  • Assignee: Inventergy, Inc.
  • Correspondent: NOT RETRIEVED
  • Context: Securitization housekeeping — release of the January insider security interest.

• 2014-03-25 (executed) / recorded 2014-03-25 — Reel NOT RETRIEVED

  • Conveyance: Security Interest
  • Assignor: Inventergy, Inc.
  • Assignee: Hudson Bay IP Opportunities Master Fund, LP, as Collateral Agent for certain buyers
  • Correspondent: NOT RETRIEVED
  • Context: Securitization — expansion of the Hudson Bay collateral package.

• 2014-10-01 (executed) / recorded 2014-10-01 — Reel NOT RETRIEVED

  • Conveyance: Security Interest
  • Assignor: Inventergy, Inc.
  • Assignee: DBD Credit Funding LLC
  • Correspondent: NOT RETRIEVED
  • Context: Securitization — DBD Credit Funding enters the chain. DBD is the Fortress affiliate that later takes control of monetization. This is the seed of the Fortress takeover.

• 2014-10-14 (executed) / recorded 2014-10-14 — Reel NOT RETRIEVED

  • Conveyance: Release by Secured Party
  • Assignor: Hudson Bay IP Opportunities Master Fund, LP
  • Assignee: Inventergy, Inc.
  • Correspondent: NOT RETRIEVED
  • Context: Securitization — Hudson Bay exit collateral; replaced by DBD.

• 2014-11-03 (executed) / recorded 2014-11-03 — Reel NOT RETRIEVED

  • Conveyance: Release by Secured Party
  • Assignor: Hudson Bay IP Opportunities Master Fund, LP, for itself and as Collateral Agent for certain buyers
  • Assignee: Inventergy, Inc.
  • Correspondent: NOT RETRIEVED
  • Context: Securitization — final Hudson Bay release. DBD now the sole secured party of record.

• 2017-01-04 (executed on or about December 2016; RPX reports a December 2016 DBD security agreement covering 150+ assets) / recorded 2017-01-04 — Reel NOT RETRIEVED

  • Conveyance: Security Interest
  • Assignor: EON Communication Systems, Inc.; Inventergy Global, Inc.; Inventergy Holding, LLC; Inventergy Innovations, LLC; Inventergy IoT, LLC; Inventergy LBS, LLC; Inventergy, Inc.
  • Assignee: DBD Credit Funding LLC, as Collateral Agent
  • Correspondent: NOT RETRIEVED
  • Context: Securitization / distressed restructuring — the December 2016 Fortress restructuring agreement, disclosed in Inventergy's 2016-12-29 Form 8-K, giving Fortress sole monetization discretion. Corresponds to RPX's report of "a December 2016 security agreement between Inventergy and DBD involving over 150 assets."

• 2017-06-19 (executed ~May 2017; Inventergy's 2017-05-01 press release announced it) / recorded 2017-06-19 — Reel NOT RETRIEVED

  • Conveyance: Assignment of Assignors' Interest
  • Assignor: Inventergy, Inc.
  • Assignee: INVT SPE LLC
  • Correspondent: NOT RETRIEVED
  • Context: Transfer to asserter — 740 telecom patents assigned to a Delaware special-purpose entity managed and controlled by Fortress's DBD Credit Funding LLC, with Fortress holding sole discretion to "license, sell or sue." Current assignee of record.

No later assignment appears in the record. Google Patents still lists INVT SPE LLC as current assignee, and RPX reports INVT SPE as a purchaser as recently as 2022 (Huawei → INVT SPE, assignments executed 2022-09-24, reported 2022-10-28). There is no transfer to RPX, AST, LOT Network, Unified Patents, or OIN.

Correspondent analysis — cannot be performed. This is the single biggest gap in this report. The site's briefing correctly identifies the correspondent as the highest-value tell, and I have no correspondent data for any of the ten recording events above. Treat the "repeat correspondent" signal below as unclear, not negative. If you can export the Assignment Center rows, the check is: do the 2014-01-03 (Panasonic→Inventergy), 2014-10-01 (DBD security), 2017-01-04 (DBD security), and 2017-06-19 (Inventergy→INVT SPE) recordings name a common attorney or firm? Four recordings under one correspondent is the classic signature.

Timeline diagram

timeline
    title Ownership of US 6611509
    1999 : Application filed by Matsushita Electric
    2003 : Patent issued
    2008 : Name change to Panasonic Corporation
    2013 : Panasonic sells portfolio to Inventergy
    2014 : Assignment to Inventergy recorded
         : DBD Credit Funding takes security interest
    2016 : Fortress restructuring agreement signed
    2017 : Assigned to INVT SPE LLC
         : Fortress gains sole monetization control
    2019 : Patent reaches anticipated expiration

NPE / troll-pattern signals

1. Shell-entity transfer — PRESENT.
The patent left an operating electronics manufacturer and landed in a licensing-only SPV. Recorded 2014-01-03: Panasonic Corporation → Inventergy, Inc., a Nasdaq-listed company with no product revenue and 3 employees (S&P Capital IQ company profile via MarketScreener). Recorded 2017-06-19: Inventergy, Inc. → INVT SPE LLC, a Delaware LLC whose Rule 7.1 disclosure (N.D. Cal. 3:19-cv-07651, filed 2019-12-03) states it is "wholly-owned by CF INVIT Holdings LLC … and Inventergy, Inc." — i.e., a single-purpose holding vehicle named "INVT SPE" (special purpose entity), managed by Fortress's DBD Credit Funding LLC. Both name-suffix and single-purpose character are evidenced, not inferred from the name alone.

2. Known asserter in the chain — PRESENT.
Two entities in this chain appear on public asserter directories:

• INVT SPE LLC is listed in the Stanford NPE Litigation Database as a patent asserter (INVT SPE LLC v. Apple, 2:17-cv-03738; v. HTC, 2:17-cv-03740; v. ZTE, 2:17-cv-06522, all D.N.J.), and is tagged "NPE (Patent Assertion Entity)" in Unified Patents' PTAB portal (e.g., IPR2018-01557, patent owner Invt SPE LLC).
• Inventergy Global, Inc. is described by RPX as "publicly traded NPE Inventergy Global, Inc." and its Feb 2017 Apple/HTC suits are catalogued as an NPE campaign.
• The controller is Fortress Investment Group LLC, named as a defendant in Intel/Apple's antitrust suit (N.D. Cal. 3:19-cv-07651) and described in the RPX 2022 report as operating through DBD Credit Funding LLC.
  Note for precision: Fortress/INVT SPE is not on the checklist list given in the briefing (Acacia, Marathon, IV, Wi-LAN, Conversant, Vringo, etc.). It is nonetheless a well-documented high-frequency asserter family, captured here on the strength of the Stanford and Unified Patents entries rather than by name-matching to a list.

3. Repeat correspondent across the chain — UNCLEAR (data not retrieved).
I could not obtain correspondent-of-record for any recording. Positively, the other side of the tell does show a repeat player: the same counterparty — DBD Credit Funding LLC, a Fortress affiliate — appears as assignee/security holder on the 2014-10-01, 2017-01-04, and (as manager/controller of the assignee) 2017-06-19 recorded entries. Whether the filing attorney is likewise constant across the 2014-01-03, 2014-10-01, 2017-01-04 and 2017-06-19 recordings is the open question and is the single highest-value item to pull from the Assignment Center.

4. Cascading transfers — PRESENT (in the security layer; weak in the equity layer).
Two equity hops (Panasonic → Inventergy 2014-01-03; Inventergy → INVT SPE 2017-06-19) span ~41 months — outside the 24-month window, so the equity chain alone is not a cascade. But the security layer cascades hard: seven recordings in ten months of 2014 (2014-01-27 Beyers; 2014-01-29 Hudson Bay; 2014-03-25 Beyers release; 2014-03-25 Hudson Bay security interest; 2014-10-01 DBD; 2014-10-14 Hudson Bay release; 2014-11-03 Hudson Bay release) followed by the 2017-01-04 seven-assignor DBD security interest. That is a classic debt-layered securitization structure, restructured into an outright assignment within ~6 months of the final security recording.

5. Pre-litigation transfer — NOT PRESENT as to this patent.
I found no litigation naming US 6,611,509. The patents asserted in INVT SPE's and Inventergy's campaigns (per RPX and RPX's case listings) are 6,466,563; 6,611,676; 6,760,590; 7,206,587; 7,339,949; 7,760,815; 7,764,711; 7,848,439 — 6,611,509 is conspicuously absent. The Intel/Apple antitrust SAC reportedly identifies only three non-SEP INVT/Inventergy patents ('579, '242, '620), again not this one. So there is no assignment-then-sue pairing to cite here. Note the chronology that does exist for the portfolio generally: Inventergy sued Apple and HTC in February 2017 (1:17-cv-00196, 1:17-cv-00200), INVT SPE was created in March 2017, and the assignment to INVT SPE was recorded 2017-06-19 — i.e., for the asserted siblings, the SPV received title after suits were filed. For this patent, that pattern has no counterpart.

6. Bankruptcy fire-sale — NOT PRESENT (formally); distressed-restructuring analog present.
There is no Chapter 7/11 proceeding in this chain. What exists is the functional equivalent: per RPX, Inventergy was "unable to make scheduled payments on $10M of debt" and entered a December 2016 restructuring agreement with Fortress, disclosed in its 2016-12-29 Form 8-K, transferring 740 patents. The 2017-01-04 recorded security interest names seven affiliated Inventergy/EON assignors as collateral grantors — the fingerprint of a distressed group restructuring. This is a creditor-driven work-out, not a bankruptcy sale.

7. Privateering — PRESENT.
Panasonic — an operating company and 3GPP standards participant — sold ~500 3G/4G assets to a licensing-only NPE while retaining a license back and sharing in net revenue (Inventergy/Panasonic Patent Purchase Agreement effective 2013-10-21, §2.5 Grant-Back; §1(l)–(q) Gross/Net Revenue definitions; amended 2015-12-31). That is the textbook structure in which an operating company externalizes assertion while keeping freedom to operate and a share of recoveries. Acquisitions from Huawei and Nokia used the same template. The later assertion targets were Panasonic's competitors' customers (Apple, HTC, ZTE).

8. Defensive aggregator — NOT PRESENT.
The chain terminates at INVT SPE LLC (Fortress-controlled), which is an active asserter, not a defensive aggregator. No RPX, AST, LOT Network, Unified Patents, or OIN assignment appears in the record.

Verdict

NPE — high confidence.

Four independent signals are evidenced rather than inferred: (i) a shell-entity transfer off an operating manufacturer at the 2014-01-03 recording of the Panasonic → Inventergy assignment, followed by a second hop to the single-purpose INVT SPE LLC at the 2017-06-19 recording; (ii) known asserters in the chain — Inventergy Global per RPX, and INVT SPE LLC listed in the Stanford NPE Litigation Database and tagged "NPE (Patent Assertion Entity)" in Unified Patents' PTAB portal; (iii) privateering, since Panasonic sold with a grant-back license and a net-revenue share under the PPA effective 2013-10-21 and then watched its competitors' customers get sued; and (iv) a securitization cascade of seven 2014 security recordings (2014-01-27 through 2014-11-03) culminating in the creditor restructuring recorded 2017-01-04 that handed Fortress sole monetization discretion.

Two honest qualifications. First, US 6,611,509 itself was never asserted in any proceeding I could find — the NPE status attaches to its owners, not to this patent's own litigation history. Second, the patent expired on its anticipated expiration date of 2019-03-09, so whatever assertion value it carried is spent; it survives only as part of the 740-patent INVT SPE collateral/monetization pool. The one item that could upgrade or downgrade the "repeat correspondent" reading is the correspondent-of-record on the four key recordings, which I could not retrieve.

Verification links:

• USPTO Assignment Center (search patent 6,611,509): https://assignmentcenter.uspto.gov/
• Mirror: https://assignment.uspto.gov/patent/index.html
• Google Patents legal events for this patent: https://patents.google.com/patent/US6611509/en
• RPX on the Fortress/INVT SPE chain: https://litigation.rpxcorp.com/news/7945-fortress-takes-control-of-740-telecommunications-patents-from-inventergy and https://litigation.rpxcorp.com/news/72374-fortress-receives-patents-from-huawei
• Stanford NPE Litigation Database, INVT SPE LLC: https://npe.law.stanford.edu/party/invt-spe-llc
• Inventergy 8-K on the Panasonic acquisition (2014-01-07): https://capedge.com/filing/[1084752](/patent/1084752)/0001144204-14-001009/8K

I'll research US patent 6611509 and its cited prior art. Let me start with targeted searches.

Let me dig into the specific citation table for US6611509.

Let me try to retrieve the actual citation list from patent databases directly.

US 6,611,509 B1 — Prior-Art / Citation Analysis

0. Scope note and a hard limitation I must flag up front

My available tool is a general web search, not a live authenticated connection to USPTO Patent Public Search / PatentCenter. I ran multiple targeted searches, but I was unable to retrieve the authoritative "References Cited" (front‑page) listing for US 6,611,509 B1 itself. Search result pages for Google Patents and other aggregators returned truncated and mixed citation tables (largely belonging to the citing patent US 7,158,496 B2, on which US 6,611,509 B1 appears as a cited reference). Under the operating rule not to fabricate, I will (a) state exactly what I verified, (b) state plainly what I could not verify, and (c) give you the §102 analytical framework and the reference‑identification leads with explicit confidence labels. I have not auto‑corrected any number.

1. Verified bibliographic data for US 6,611,509 B1

Source: https://patents.google.com/patent/US6611509/en and https://patents.google.com/patent/US20050002349

The EP 0 948 221 family linkage is independently corroborated by a PCT search‑report family annex at https://patentimages.storage.googleapis.com/03/c7/d3/d584cf0588e8aa/WO2003079576A3.pdf, which lists "EP 0948221 A 06‑10‑1999 … US 2002150074 A1 17‑10‑2002 … US 6611509 B1 26‑08‑2003."

2. The claim framework any §102 reference must meet

The specification and abstract fix the scope of independent claim 1 (and its counterpart method/system claims). The elements you must test each reference against, element‑by‑element, are:

1. CDMA/TDD system — same radio frequency band, forward and reverse links alternating in assigned time slots.
2. A base‑station apparatus having a control section that performs the slot assignment.
3. One or more fixed forward‑link time slots placed at a predetermined interval within a communication frame divided into a plurality of time slots.
4. Remaining time slots allocated between forward‑link and reverse‑link slots according to a ratio of total forward‑link information volume to total reverse‑link information volume in the system.
5. A control channel signal including a synchronization control channel signal transmitted in the fixed forward‑link time slots.
6. Forward‑link and reverse‑link traffic channel signals transmitted in the allocated slots, according to the number of slots respectively required for the respective information volume.

Dependent/embodied features that frequently appear in the later claims and in the embodiments (relevant if a reference is asserted against a dependent claim):

• the slot immediately following a sync‑control slot is a reverse‑link slot (FIG. 4 / FIG. 5 embodiments);
• the common control channel is repeated every 2 / 4 / 8 / 16 slots (FIGS. 3–6);
• the mobile station acquires synchronization by integrating correlation values over the fixed interval (FIG. 7 / FIG. 8; fifth embodiment); and
• weighting of measured reception quality of a forward slot immediately preceding the reverse‑link transmit slot for open‑loop TPC (sixth and seventh embodiments, FIGS. 9–10).

§102 legal standard applied: anticipation requires that a single prior‑art reference disclose every one of elements 1–6, arranged as claimed. A reference disclosing dynamic slot allocation or TDD/CDMA generally, without the fixed‑interval synchronization slot plus information‑volume‑ratio allocation of the remaining slots, cannot anticipate claim 1 — it is at most §103 art.

3. What I could and could not verify about the citations

Could not verify (explicitly): the examiner‑cited patent and non‑patent references printed on the face of US 6,611,509 B1.

What the searches actually surfaced (with provenance warning): a Google Patents "Patent Citations (10)" table on the record of US 7,158,496 B2 containing these entries —

• US 5,369,664 A — 1991‑08‑12 / 1994‑11‑29 — Matsushita Electric Industrial Co., Ltd. — "Mobile communication system"
• US 5,748,623 A — 1993‑09‑03 / 1998‑05‑05 — NTT Mobile Communications Network, Inc. — "Code division multiple access transmitter and receiver"
• US 6,018,528 A — 1994‑04‑28 / 2000‑01‑25 — AT&T Corp. — "System and method for optimizing spectral efficiency using time‑frequency‑code slicing"
• WO 1996/019883 A1 — 1994‑12‑19 / 1996‑06‑27 — Stanford Telecommunications, Inc. — digital generation/combination of multiple CDMA/FDMA signals
• DE 19549148 A1 — 1995‑12‑29 / 1997‑07‑03 — Siemens AG — radio transmission of digital signals
• EP 0 809 364 A2 — 1996‑05‑20 / 1997‑11‑26 — Mitsubishi Denki K.K. — "Spread spectrum communication system"
• EP 0 876 008 A1 — 1997‑05‑02 / 1998‑11‑04 — Siemens AG — "Adaptive data rate TDMA/CDMA communications system"
• US 6,611,509 B1 — 1998‑03‑10 / 2003‑08‑26 — Matsushita — "CDMA/TDD mobile communication system and method"

Source: https://patents.google.com/patent/US7158496 (citation table)

My assessment of that table: because US 6,611,509 B1 itself appears inside it, this is almost certainly the citation list of US 7,158,496 B2 (i.e., US 6,611,509 is prior art to US 7,158,496), not the "References Cited" front page of US 6,611,509. I am therefore not representing those seven references as the citation list of US 6,611,509. One internal cross‑check supports this caution: EP 0 876 008 A1 published 1998‑11‑04, which is after the 1998‑03‑10 priority date of US 6,611,509 — it could not be §102(a) prior art to US 6,611,509, which is consistent with it belonging to a later patent's table.

Non‑patent literature (same provenance caveat): the same page listed three NPL items — He, J. et al., "A MAC Protocol Supporting Wireless Video Transmission Over Multi‑Code CDMA Personal Communication Networks," Elsevier Science B.V., 1998, pp. 1256‑1268; Nikula, E. et al., "Frames Multiple Access for UMTS and IMT‑2000," IEEE, Apr. 1998; and Woodworth, C. et al., "Spectrally Efficient Universal Time Slots Using Time‑Frequency‑Code Slicing," IEEE, 1994, pp. 1009‑1013. I flag these as leads only, not confirmed citations of US 6,611,509.

One genuinely confirmed citation observation: Korean registration KR 10‑1384837 B1 (Samsung Electronics, registered 2014‑04‑07) lists US 6611509 B1 as a prior‑art reference in its "선행기술조사문헌" (prior‑art documents searched) field. Source: https://patentimages.storage.googleapis.com/01/7f/71/77f8f5010ebceb/KR101384837B1.pdf. That confirms US 6,611,509 is itself citable art — it does not tell us what it cited.

4. §102 analysis — per reference, on the merits

Because I cannot confirm which references the examiner actually cited, I am giving you the substantive §102 test for each candidate lead, so the analysis is usable regardless of which references turn out to be on the face of the patent. Confidence labels: [H] high, [M] moderate, [L] low / needs verification.

A. US 5,369,664 A — Matsushita, filed 1991‑08‑12, pub. 1994‑11‑29 ("Mobile communication system") [M]
A pre‑1994 TDD/cellular slot‑assignment disclosure from the same assignee. Potential §102 target: claims directed to the slot‑assignment/frame structure per se — but only if it discloses allocation of remaining slots by reference to a forward/reverse information‑volume ratio (element 4) and a fixed‑interval sync slot (element 3). Its age and the absence of CDMA/TDD spread‑spectrum disclosure make full anticipation of claim 1 unlikely; more probable §103 role.

B. US 5,748,623 A — NTT Mobile Communications Network, filed 1993‑09‑03, pub. 1998‑05‑05 ("Code division multiple access transmitter and receiver") [M]
CDMA transmitter/receiver art (spreading, correlation detection — the FIG. 2/FIG. 7 hardware of the patent). Potential §102 target: only those dependent claims reciting spreading/correlation‑detection structure. It does not, on its face, address fixed‑interval synchronization slots or information‑volume‑ratio slot allocation, so it cannot anticipate claim 1.

C. US 6,018,528 A — AT&T Corp., filed 1994‑04‑28, pub. 2000‑01‑25 ("System and method for optimizing spectral efficiency using time‑frequency‑code slicing") [M]
Discloses dynamic time/frequency/code resource slicing to optimize spectral efficiency — conceptually adjacent to element 4 (allocating slots by traffic demand). This is the strongest §103 candidate among the traditional art (motivation to allocate slots according to traffic asymmetry), but its publication date (2000) and its frequency/code‑slicing framing weaken a §102(a) attack on a 1998‑03‑10 priority; §102(e) would require a U.S. filing before that date, which the 1994 filing date satisfies if the disclosure is enabling as to element 3/5.

D. WO 1996/019883 A1 — Stanford Telecommunications, filed 1994‑12‑19, pub. 1996‑06‑27 [L]
Practical generation/combination of many CDMA/FDMA signals — relevant to the multiplexing/coding sections of FIG. 2, not to the claimed frame‑allocation controller.

E. DE 19549148 A1 — Siemens AG, filed 1995‑12‑29, pub. 1997‑07‑03 [L]
Method and arrangement for radio transmission of digital signals. General TDD framing art; not shown to disclose the fixed‑interval sync slot plus volume‑ratio allocation combination.

F. EP 0 809 364 A2 — Mitsubishi Denki K.K., filed 1996‑05‑20, pub. 1997‑11‑26 ("Spread spectrum communication system") [M]
A pre‑priority (1997) spread‑spectrum/TDD‑adjacent disclosure. The most likely reference to be run against the synchronization‑acquisition dependent claims (mobile station integrating correlation values at fixed intervals — FIG. 8 embodiment) and possibly §103 against the sync‑slot aspect of claim 1.

G. EP 0 876 008 A1 — Siemens AG, filed 1997‑05‑02, pub. 1998‑11‑04 [L / date bar]
"Adaptive data rate TDMA/CDMA communications system." Its subject matter (adaptive‑rate TDD/CDMA slot allocation) is on‑point for element 4, but its publication date post‑dates the 1998‑03‑10 priority date, so it is not §102(a) art as to US 6,611,509. It can only matter via a §102(e)‑type route (U.S. filing before the priority date) or as §103 art. I flag this as a likely reason the table in §3 above belongs to a different patent.

H. NPL — Nikula et al., "FRAMES Multiple Access for UMTS and IMT‑2000," IEEE, Apr. 1998 [L / date bar]
Highly relevant thematically to CDMA/TDD frame and slot structure, but dated April 1998, i.e., after the JP priority of 1998‑03‑10; it would be usable only against a later‑dated claim, not against the 1998‑03‑10 priority.

I. NPL — Woodworth et al., "Spectrally Efficient Universal Time Slots Using Time‑Frequency‑Code Slicing," IEEE, 1994, pp. 1009‑1013 [L]
Pre‑priority and thematically consistent with slot‑allocation flexibility (element 4). A plausible §103 building block; standalone‑anticipation of claim 1 is unlikely because it lacks the synchronization‑control‑channel‑in‑fixed‑slots limitation.

Bottom line on §102: on the record as I have it, no single reference is shown to anticipate independent claim 1, because none of the candidates is shown to disclose all of (i) fixed forward‑link slots at a predetermined interval carrying the synchronization control channel, and (ii) allocation of all remaining slots by ratio of total forward‑link to reverse‑link information volume. The realistic invalidity theories are combinations under §103 (e.g., a TDD framing/slot‑allocation reference in view of a CDMA synchronization/spreading reference). If you have the actual examiner citations, the claim‑by‑claim test above can be applied directly.

5. Litigation / validity context (useful for prior-art scoping)

US 6,611,509 has been worked over in the INVT SPE campaigns: it appears as "Pana‑11," US 6,611,509, granted 8/26/2003, App. 09/264,826, filed 3/9/1999, in an INVT SPE proxy statement: http://ir.inventergy.com/proxy-statements/content/0001144204-16-[141762](/patent/141762)/0001144204-16-141762.pdf. It also appears in the file‑history exhibit for Apple Inc. v. INVT SPE LLC, IPR2018‑01475: https://www.docketalarm.com/cases/[PTAB](/ptab)/IPR2018-01475/Apple_Inc._v._INVT_SPE_INC/docs/... That petition record is a good place to find the challenger's prior‑art mapping onto this family (that IPR concerned US 7,760,815, but the exhibit lists US 6,611,509 as a family member, and the same petitioner art set is instructive).

6. How to close the gap with certainty (recommended verification steps)

1. USPTO Patent Public Search (https://ppubs.uspto.gov) → retrieve US 6,611,509 B1 → "References Cited" listing on the front page, and the "Cited By" (forward) list separately — do not conflate the two.
2. PatentCenter → Application 09/264,826 → Image File Wrapper → the PTO‑892 (Notice of References Cited) and any PTO‑1449 (Information Disclosure Statement); the examiner‑cited items are the §102/§103 candidates.
3. EPO Global Dossier / publication server for EP 0 948 221 A2, the European sibling — its European search report cites essentially the same art family (the WO 2003/079576 A3 annex already links EP 0 948 221 A to US 6,611,509 B1).
4. Check the divisions/continuations US 6,807,162 B2, US 6,973,065 B2 and US 7,778,224 B2, whose front pages typically reproduce the same "References Cited" set.

If you can paste the front‑page "References Cited" block (or the PTO‑892) for US 6,611,509, I will run the exact element‑by‑element §102 anticipation chart against claim 1 and each dependent claim immediately, with pin cites.

I'll first try to recover the actual prior-art references for this patent, since the material supplied to me contains only Google Patents' algorithmic "Prior art keywords" list (time slots / forward link / control channel / assigned / reverse link) — not a cited-references table. If you have a different "Prior Art section" in mind, tell me and I'll re-anchor.

Let me pull the '509 patent's own front-page references and any post-issuance challenge record.

§ 103 Obviousness Analysis — US 6,611,509 B1

0. Preliminary: what "the Prior Art section of this page" actually contains

Before analyzing, an important scope flag.

The page text supplied to me (the Google Patents record for US 6,611,509) contains a "Prior art keywords" field only:

time slots, forward link, control channel, assigned, reverse link

That is Google's algorithmic keyword extraction, not a references-cited table. The supplied page text contains no "Patent Citations," "References Cited," or "Non-Patent Citations" table. So I cannot analyze "the prior art of record" as a closed set — because the fetched page did not give me one.

What I did recover by search, and its exact provenance:

• A citation table containing US 5,369,664 A; US 5,748,623 A; US 6,018,528 A; WO 1996019883 A1; DE 19549148 A1; EP 0809364 A2; EP 0876008 A1 plus three non-patent citations, and which also lists US 6,611,509 B1 in an adjacent column. However, that table appeared on the Google Patents page for US 7,158,496 (https://patents.google.com/patent/US7158496), not on the '509 page.
• Decisive disqualifier for that table as the '509's own: one of its non-patent citations is Nikula et al., "FRAMES Multiple Access for UMTS and IMT-2000," IEEE, April 1998. That post-dates the '509 priority date of 1998-03-10, so it cannot be prior art to the '509. That table therefore very likely belongs to a later Matsushita application, and I am not treating it as the '509's record.

Bottom line: I have no verified references-cited list for US 6,611,509. Everything below is (a) the '509's own admitted prior art (its Background / FIG. 1), (b) well-known general art in the TDMA/TDD slot-assignment field whose dates I verified individually, and (c) clearly-labeled inferences. I say explicitly where I have not verified the disclosure text of a reference.

1. Governing law and posture

• Application filed 1999-03-09; priority 1998-03-10. Pre-AIA 35 U.S.C. § 103(a) applies (filing before 2013-03-16).
• The § 102 cutoffs: § 102(b) for printed publications dated on/before 1998-03-09; § 102(a) for publications before the invention date; § 102(e) for U.S. patents/applications whose U.S. filing date precedes the invention date, even if they issued later.
• Standard: Graham v. John Deere factors; KSR Int'l v. Teleflex (obvious to try / predictable combinations / market- or design-driven motivation). § 103(c) (pre-AIA) is noted where common ownership matters.
• Status caveat: the '509 expired 2019-03-09 per its record. Any § 103 analysis is retrospective.
• Name-collision warning: do not conflate this patent with US 6,611,676 (which was litigated — Apple/HTC v. INVT, IPR2018-01473, Fed. Cir. 20-1859 (Apr. 13, 2021)). I found no IPR, PGR, or district-court validity challenge directed at 6,611,509. The INVT proceedings I located concern 7,764,711; 7,848,439; 7,269,439; 6,760,590; and 6,611,676 — not the '509.

2. The claim to be tested

Per the earlier section, claim 1 (the only independent claim I verified) requires, in a CDMA/TDD system with a frame of slots each assigned to a forward or reverse link:

1. Assignor: assigns a forward link common control channel to position-fixed slots disposed at regular intervals; and
2. Controller: assigns forward link user information channel and reverse link user information channel to the remaining slots in accordance with a ratio of forward-link information volume to reverse-link information volume.

Dependent claims verified: 2 (common control = synchronization control channel), 3 (every second slot), 4 (every fourth slot).

The invention's stated advance over the FIG. 1 prior art is that when the UL/DL split is changed for asymmetric traffic, the sync-channel configuration "becomes irregular," lengthening synchronization acquisition, and the UL/DL slot spacing becomes large enough to degrade open-loop power control.

3. Candidate prior art (dates verified; disclosure depth flagged)

Excluded / flagged: EP 0 876 008 A1 (Siemens, "Adaptive data rate TDMA/CDMA") published 1998-11-04 — after the '509 priority date. It is prior art only if its 1997-05-02 priority date can be used and only under a § 102 theory that reaches foreign priority (pre-AIA § 102(e) does not reach a non-US-published EP application). Do not rely on it. Likewise the Nikula FRAMES paper (Apr. 1998) is not prior art.

4. Combination 1 (primary): US 5,594,720 + the admitted CDMA/TDD architecture

Proposed ground. Claim 1 would have been obvious over US 5,594,720 in view of the CDMA/TDD architecture admitted in the '509's own Background (FIG. 1) — optionally with US 5,555,789 for the CDMA/TDD specifics.

Element mapping.

• Frame of slots each assigned FL or RL — the admitted FIG. 1 (slots 0–3 FL, 4–7 RL); also inherent in US 5,594,720's TDMA/TDD and STDD frame formats.
• FL common control channel — admitted FIG. 1 ("common control channel 3 such as synchronization control channel" multiplexed into forward link 2). US 5,594,720 likewise uses dedicated control slots in the frame.
• FL/RL user information channels on the remaining slots according to a ratio of FL to RL information volume — US 5,594,720's STDD/PSTDD: "slots are dynamically allocated between uplink and downlink users," "Us and Ds are varied dynamically in such a way as to improve overall system quality and capacity." Varying the number of uplink vs. downlink slots as traffic demands shift is allocating residual slots in accordance with the ratio of the two directions' information volumes.
• Control channel on position-fixed slots at regular intervals — this is the one element not squarely taught by US 5,594,720's dynamic scheme, and it is supplied by the admitted art / ordinary skill (see motivation below).

Motivation to combine (KSR-adequate).

1. Same field, same problem. Both are frame-structure patents for cellular systems that allocate frame slots between uplink and downlink. US 5,594,720 expressly frames the problem as "improving overall system quality and capacity" for asymmetric two-way traffic.
2. Design need. Once a POSITA adopts a dynamic, volume-proportional UL/DL split, the mobile station loses the ability to know, a priori, where the broadcast/sync channel sits — precisely the problem the '509's Background acknowledges. The POSITA's conventional answer, well established in TDD/TDMA art (DECT's fixed broadcast slot; PHS control slot; GSM BCCH on the beacon carrier), is to pin the broadcast/control channel to a fixed, regularly recurring slot position and let only the traffic slots float.
3. Predictable results, no new hardware. The change is a scheduling decision in the base station's control section (control section 125). Both references are software/configurable frame schedulers.
4. Additional predictable benefit. Keeping a periodic FL control slot in a fixed grid also guarantees an FL control slot immediately preceding a reverse-link slot, which the '509 itself explains improves the freshness of the open-loop TPC measurement — an advantage that follows automatically from the pinning, not from any unexpected discovery.

Counter-argument to expect. Patent Owner would argue US 5,594,720's dynamic allocation makes the control-slot position move with the UL/DL boundary, so the combination teaches away. Rebuttal: US 5,594,720 does not require the control slots to move; and in DECT/PHS-type art the broadcast slot is already fixed by design, so there is no teaching away.

5. Combination 2: focus on the "position-fixed periodic grid" element

Ground. A TDD/CDMA reference that places the sync/broadcast channel at a known periodic slot position (e.g., US 5,555,789; or the DECT/PHS/GSM standards art) in view of a dynamic asymmetric slot-allocation reference (US 5,594,720, or US 6,018,528's time-frequency-code slicing, or the Omnipoint interleaved-TDD family).

This is the mirror image of Combination 1 and is the stronger framing if a POSITA is found to start from a fixed-sync TDD system rather than from a dynamic-allocation system. Motivation: the well-documented demand for asymmetric capacity (downlink-heavy data services) in TDD, combined with the mandatory requirement that a powering-on mobile find the broadcast channel — a requirement the '509 admits is the central problem.

6. The dependent claims

• Claim 2 (common control channel = synchronization control channel): every TDD/DS-CDMA system broadcast/sync channel; inherent in the admitted FIG. 1. Clearly obvious.
• Claim 3 / Claim 4 (every second / every fourth slot): selecting the repeat interval of a periodic broadcast/sync channel is a classic finite number of identified, predictable solutions (KSR). The '509 discloses 2, 4, 8 and 16 as interchangeable variants and expressly says "It is preferable to use the arbitrary number of time slots … other than every four time slots." That is a concession that the interval is a design choice, and the specification supplies no criticality or unexpected result. I have not verified whether any single reference discloses the specific 2-slot and 4-slot grids, so this is a "routine design choice made obvious by the specification's own breadth" argument, not an anticipation argument.

7. Claim-1 nonobviousness counterpoints a Patent Owner could press

1. The '509's FIG. 3(C)/(D) reverse-link placement. The specification claims that the reverse-link slots end up "just after" the control slots. If "position-fixed … at regular intervals" were construed to require a specific relative ordering of RL slots (not merely any periodic FL control grid), a primary reference's unconstrained dynamic allocation might not teach it — though it would still be an obvious configuration choice once the grid is fixed.
2. "In accordance with a ratio of information volume" could be argued to require an explicit computed ratio, as opposed to a traffic-driven, incremental slot reallocation. This is the most plausible claim-differentiating construction.
3. No secondary considerations are apparent: no unexpected results, no licensing nexus specific to the '509, no industry praise tied to this claim. The patent expired in 2019.

8. Conclusion

On the record I could verify, claim 1 would likely have been held obvious under pre-AIA § 103(a) over US 5,594,720 in view of the CDMA/TDD architecture admitted in the '509's own Background — and, secondarily, over a periodic-broadcast TDD reference (e.g., US 5,555,789) in view of a dynamic UL/DL slot-allocation reference. Claims 2–4 are weaker still (sync channel naming; finite-interval design choice). The single most contestable limitation is the conjunction of an explicitly volume-ratio-driven allocation with the position-fixed control grid.

9. Explicit uncertainties (do not treat as verified)

1. I never obtained the '509's actual references-cited list. The only tables I recovered belong to other patents (US 7,158,496 / related pages), and one of their NPL items post-dates the '509 priority date.
2. I did not verify the disclosure text of US 5,555,789, US 5,748,623, US 6,018,528, US 5,748,484, US 5,802,046, US 5,689,502, US 5,959,980, EP 0 809 364 A2, or DE 19549148 A1. I have their bibliographic data only; my element-mapping for those is therefore provisional.
3. Full claim set still unverified. Only claims 1–4. If additional independent claims exist (a mobile-station claim or a synchronization-acquisition method claim, as in divisional US 6,807,162), they may be narrower and harder to invalidate.
4. No file history obtained for the '509 (the file-history PDF surfaced in search is for US 7,760,815, not the '509). I cannot say what the examiner actually rejected or allowed.
5. No '509-specific IPR/PGR or validity ruling found. Assume none exists unless you have a citation to the contrary.
6. This is a technical invalidity hypothesis, not a legal opinion. A real § 103 contention requires verbatim claim charts, pinned column/line cites, and POSITA testimony.

Sources used: https://patents.google.com/patent/US6611509B1/en (specification, abstract, admitted FIG. 1 art, status); https://patents.google.com/patent/US5594720A/en (US 5,594,720 text/definitions); EP 1 578 163 B1 citation list (US 5,555,789, US 5,594,720, US 5,748,484, US 5,802,046, US 5,689,502, US 5,959,980); https://patents.google.com/patent/US7158496 (the citation table I excluded, containing US 5,369,664, US 5,748,623, US 6,018,528, WO 1996019883, DE 19549148, EP 0809364, EP 0876008, and the Nikula NPL); Federal Circuit 20-1859 / IPR2018-01473, IPR2018-01475, IPR2018-01476, IPR2018-01555 / IPR2019-00958 (INVT proceedings — none involving 6,611,509).