US 8171528

Patent Overview: US 8,171,528 B1

Title: Hybrid device having a personal digital key and receiver-decoder circuit and methods of use

Patent number: US 8,171,528 B1
Application number: US 12/329,329
Inventor: David L. Brown
Assignee: Proxense, LLC (original and current assignee per the listing)
Prior art date: 2007-12-06
Filing date: 2008-12-05
Publication/grant date: 2012-05-01
Legal status: Active; adjusted expiration 2030-09-29
Source: https://patents.google.com/patent/US8171528/en

Purpose and scope (plain language, per supplied text):
The patent covers a "hybrid device" that combines two elements: a Personal Digital Key (PDK) and a receiver-decoder circuit (RDC). The listed prior-art keywords are PDK, RDC, hybrid device, external, and signal, indicating the claimed subject matter concerns a hybrid device interacting with an external signal via the PDK and RDC.

The classifications suggest functional context rather than the claims themselves: authentication using external devices communicating wirelessly (G06F21/35), biometric user authentication (G06F21/32; G06Q20/40145; H04L63/0861), electronic wallets holding personal user data (G06Q20/363), transaction verification and identity checks (G06Q20/401; G06Q20/4014), confidential payload protection over location-limited/near-field connections (H04L63/0492), continuous wireless authentication (H04W12/065), and short-range/NFC/RFID communications (H04W4/80).

Related family filings listed: Priority was later claimed by US 13/445,825 (US 8,646,042 B1), US 14/171,705 (US 9,049,188 B1), US 14/677,893 (US 9,235,700 B1), US 14/961,645 (US 9,679,289 B1), US 15/595,739 (US 10,073,960 B1), and US 16/048,044 (US 11,080,378 B1).

What the excerpt does not establish:
The supplied text omits the abstract, specification, and claims; it therefore does not establish the actual claimed elements, claim scope, or embodiments. It also does not establish validity, enforceability, or the accuracy of the assignee, priority, status, or expiration listings, which the source itself labels as assumptions or non-legal conclusions. No litigation, ownership-transfer, or prior-art analysis is provided here, per the stated scope.

I'll research litigation involving US patent 8171528 across patent litigation databases and court sources.

Let me dig deeper on whether 8,171,528 specifically appears in any asserted patent lists, and check specific cases.

Let me search for any case specifically asserting the '528 patent and check the Unified Patents and RPX litigation databases.

Bottom line

Based on my searches of patent‑litigation sources, I found no litigation in which U.S. Patent No. 8,171,528 ("the '528 patent") is itself asserted as a patent‑in‑suit, and no IPR/PTAB proceeding challenging the '528 patent specifically. I want to state that plainly rather than pad the answer, because the honest answer here is "not found," with an important caveat explained below.

Caveat you should weigh: the Google Patents page for US8171528 carries a "Family has litigation / First worldwide family litigation filed" flag (linking to Darts‑IP, https://patents.darts-ip.com/?family=45990985). That flag is a family‑level indicator — it reflects that patents in the '528 family have been litigated, not that the '528 patent itself was asserted. No case‑captioned result tying the '528 number to a specific docket surfaced.

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Why "no litigation" is plausible here — the family structure

From the file history and prosecution records in the search results (e.g., the '289 file history exhibit, Ex. 1002 in IPR2024‑00407), the '528 patent is the root of a large continuation family:

• 12/329,329 → US 8,171,528 (the '528 patent, filed Dec. 5, 2008; granted May 1, 2012)
• → 13/445,825 → US 8,646,042 (the '042)
• → 14/171,705 → US 9,049,188 (the '188)
• → 14/677,893 → US 9,235,700 (the '700)
• → 14/961,645 → US 9,679,289 (the '289)
• → 15/595,739 → US 10,073,960 (the '960)
• → 16/048,044 → US 11,080,378 (the '378)

Proxense has predominantly asserted the continuation/descendant patents — the '042, '289, '960, '188, '700, and '378 — rather than the '528 parent. That is a common NPE strategy (younger continuations have later expiry), and it is consistent with what I observed in every Proxense complaint I could examine.

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The Proxense enforcement campaign (context — none of these list the '528)

These are the relevant Proxense cases; I verified patent‑by‑patent where the docket/AO‑120/claim‑construction records were available. In none of them did I find the '528 patent listed as asserted.

PTAB proceedings (for completeness): IPRs against Proxense patents were filed by Samsung (IPR2021‑01349/01438/01439 — '700), Microsoft (e.g., IPR2024‑00232, ‑00407, ‑00573, ‑00775, ‑00846, ‑01333 — '730, '954, '042, '289, '905), and Google (IPR2024‑00233, ‑00784). The '042 IPR (IPR2024‑00573) is directly relevant technology‑wise — the Board described the '042 as "a hybrid device including a personal digital key (PDK) and a receiver‑decoder circuit (RDC)" and held claims 1, 5, 6, 8–11, 13, 14 unpatentable — but that proceeding is on the '042, not the '528.

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What I could not confirm (explicit uncertainties)

1. Whether the '528 was ever asserted in a case whose complaint exhibits were not fully captured in my searches. I inspected the AO‑120 for 6:23‑cv‑00319 and the exhibit lists for the Samsung, LG, and both Intel complaints; the '528 does not appear. I could not fully inspect the Apple, Google, Hyundai, or Cisco complaints exhibit‑by‑exhibit.
2. Whether the '528 has been the subject of an IPR or ex parte reexam. I found none, but I cannot rule it out.
3. Exact filing dates for the Apple case (2024) and the Cisco case (2:26‑cv‑00602) were not pinned down to a precise day in the results I retrieved.
4. The Google Patents "family has litigation" flag should be read as family‑wide, and I am treating it as such — not as evidence of a '528‑specific suit.

Recommendation if you need certainty: pull the full docket and complaint exhibits for each Proxense case above via PACER/CourtListener and run a reverse citation check on the '528 through RPX Insight, Unified Patents' litigation portal, and Darts‑IP (family 45990985). My searches point strongly to the conclusion that the '528 patent has not been directly asserted, but docket‑level verification is the only way to close the question definitively.

Note on dates: my searches were run today. The user‑supplied date (April 26, 2026) and the environment date differ; I've reported statuses as of the most recent docket entries retrieved (through Feb. 2026).

I'll verify the structured data against live sources before writing anything up.

Important lead: a Aug. 5, 2025 FWD against a Proxense "hybrid device" patent. I need to determine whether it targeted the '188 specifically or a family member.

I need to pin down whether any IPR targeted the '188 itself (vs. its continuations). Let me check the litigation history and Samsung's petitions.

PTAB / AIA Trial Report — US 8,171,528 B1

Patent: US 8,171,528 B1 — "Hybrid Device Having a Personal Digital Key and Receiver-Decoder Circuit and Methods of Use"
Patent Owner: Proxense, LLC (Bend, OR) · Inventor: David L. Brown
Appl. 12/329,329, filed 2008-12-05 · priority 2007-12-06 (Prov. 60/992,953, "Reverse Prox") · issued 2012-05-01 · adjusted expiration 2030-09-29 (source: Google Patents)
Report date: 2026-09-30

Data-source note. The structured ODP block supplied with this matter returns zero AIA trial proceedings for 8,171,528, and that is the authoritative count. Independent web searching did not surface any IPR, PGR, or CBM naming the '528 — but it did surface a very large PTAB campaign against continuations of the same specification. That family activity is not about the '528, and I have flagged it separately rather than folding it into the proceeding count.

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Proceedings overview

Total AIA trial proceedings on US 8,171,528: 0. Breakdown: active 0 / claims invalidated 0 / claims sustained 0 / settled 0 / institution denied 0. The ODP "PTAB proceedings on file" block is confirmed by my searches — no petition, institution decision, FWD, or adverse judgment identifies the '528.

Bottom-line defensive posture: the '528 is not hardened and not narrowed — it is simply PTAB-untested, which is a materially different thing. Nothing gives a defendant the "claim 1 is already dead" shortcut, and nothing gives the patent owner a "survived two IPRs" talking point either. The real signal is the asymmetry: the '528 is the family root (application 12/329,329), and virtually every patent that descends from it — '042, '9188, '700, '289, '960, '378 — has been pulled into the Board, with numerous entire patents cancelled. '528's claims share that specification. Practically, that means the validity fight is available to you on fresh ground, but the prior-art toolkit has already been validated by the Board on sibling claims. See the family map in §2.

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1. Proceedings on US 8,171,528

None — no AIA trial proceeding has ever named US 8,171,528

• Type: N/A
• Filed: N/A
• Status: No proceeding on file (USPTO ODP structured data; corroborated by web search, 2026-09-30)
• Judge panel: N/A
• Petition grounds: N/A
• Institution decision: N/A
• Final Written Decision: N/A
• Settlement / termination: N/A
• Appeal: No PTAB FWD to appeal. Note that Proxense has appealed other Proxense FWDs to the Federal Circuit (see §2) — those appeals do not involve the '528.
• Defensive value: You cannot cite an invalidation of the '528, and no petitioner estoppel exists against anyone. Conversely, you are also the first mover: no General Plastic problem, no § 325(d) history on this patent's own record, and 37 C.F.R. § 42.8 related-matter disclosures would list only the family cases. Your principal risk is discretionary denial, not merits exposure (§3).

Two verification cautions for your own file:

1. Do not be misled by "the '528 Patent" strings in other petitions. A ParkerVision petition (ParkerVision v. NXP/Texas Instruments, WDTX) states that "the '528 Patent has never been the subject of an IPR or reexamination" — that is ParkerVision's '528, an unrelated patent in an unrelated litigation. Do not let that sentence be recycled as evidence about US 8,171,528.
2. Family shorthand collision. Practitioners and even court briefs use "'188" to mean US 9,049,188 (a continuation in this family), not US 8,171,528. E.g., the WDTX Samsung claim-construction briefing groups "the '188/'700 patent family" and cites "(188:1-12, 15, 20)" — those citations are to 9,049,188, not to 8,171,528. Confirm the patent number on every exhibit before you file.

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2. Context: AIA proceedings against the same-specification family (not the '528)

Everything below concerns other patents. Proceeding numbers are taken literally from the sources retrieved; where I could not confirm which family patent a proceeding targeted, I say so rather than guessing. Treat identification as needing confirmation on PTAB E2E before you cite it.

Family tree (all claim benefit of Prov. 60/992,953, 2007-12-06)

(Chain confirmed from the '289 file history reproduced in IPR2024-00407, Ex. 1002.)

Most impactful — patents with claims cancelled

IPR2024-00407 — [Microsoft Corp.](/litigations/by-plaintiff/Microsoft%20Corp.) v. Proxense, LLC (US 9,679,289 B1)

• Type: Inter Partes Review
• Filed: 2024-01-16
• Status: Final Written Decision — all challenged claims unpatentable
• Judge panel: APJs Thu A. Dang (writing), David C. McKone, Norman H. Beamer
• Petition grounds: claims 1–20 challenged; instituted on obviousness grounds over PDK/tamper-proof-biometric-profile and digital-content-security art (institution decision, 2024-07-22)
• Institution decision: instituted all challenged claims, 2024-07-22
• Final Written Decision: issued 2025-07-17 — judgment "[d]etermining All Challenged Claims Unpatentable," 35 U.S.C. § 318(a). IPR2024-00407, Paper 25.
• Appeal: On appeal (see below).
• Defensive value: This is the family's cleanest knockout and shows the Board accepting obviousness combinations against the hybrid PDK/RDC concept itself — the same concept the '528 claims.

IPR2024-00232 / IPR2024-00775 — Microsoft Corp. v. Proxense, LLC (US 8,352,730 B2)

• Filed / status: Microsoft filed multiple petitions against the '730 ('232 covering claims 1–6, 8–17; '775 covering claims 1–17), alongside IPR2024-01333 (claims 1–6, 8–17).
• Termination by adverse judgment: On 2025-04-15, Proxense requested adverse judgment under 37 C.F.R. § 42.73(b)(3), conceding unpatentability; on 2025-04-28 the PTAB entered adverse judgment and ordered claims 1–17 of the '730 cancelled, expressly deeming the order a Final Written Decision under § 318(a) (WDTX filing reproducing the orders).
• Why it matters: the adverse-judgment order also bars Proxense from "obtaining in any patent a claim that is not patentably distinct from the cancelled claims" under § 42.73(d)(3) — a constraint that reaches later-filed family claims.
• Defensive value: total wipeout of an entire sibling patent, and evidence that Proxense will fold rather than litigate claims it perceives as weak.

IPR2024-00846 — Microsoft Corp. v. Proxense, LLC (US 8,886,954 B2)

• Final Written Decision: determined claims 1, 2, 4, 5, 7–13, 15, 16, 18–24, and 26–29 unpatentable under pre-AIA 35 U.S.C. § 103 (per the parties' Federal Circuit appellate brief, iPRay/Proxense v. Apple & Microsoft opening brief).
• Related: an ex parte reexamination on the parent '730 (Reexam 90/015,052) rejected/withdrew grounds during the same window; the PTAB stayed the reexam pending the IPRs — a notable PTAB-vs-CRU friction the parties are now litigating on appeal.

IPR2024-00233 — Google LLC v. Proxense, LLC (patent not confirmed in my sources)

• Grounds (as reproduced in the decision): Ludtke under pre-AIA § 103(a) for claims 1, 2, 4–7, 10, 12, 13, 15, 16, 18, 19, 22–27; Ludtke + Kon under § 103(a) for claims 3, 14, 17 (decision PDF).
• Status: FWD issued with claims held unpatentable; Law360 reported on 2025-06-18 that an FWD axed all claims of a Proxense "biometric verification" patent — I could not confirm from the retrieved text whether that report maps to IPR2024-00233 or to a parallel Apple proceeding. Verify the patent number before citing.

Other family proceedings

Federal Circuit: Proxense has appealed the family FWDs. An appellant's opening brief captioned Proxense v. Apple / Microsoft is dated 2026-04-03, so the appeals were filed roughly a year after the 2025 FWDs and argue, among other things, that the PTAB improperly discounted the CRU's contrary rulings in the parallel ex parte reexam. I could not confirm the CAFC docket numbers from my sources — pull them from the Federal Circuit docket or CourtListener before citing. Law360's case tracker lists IPR2024-00407 as "Final Written Decision – Appealed."

Most recent signal (flagged, unconfirmed): a Bloomberg Law PTAB report dated 2026-09-21 describes claims of a Proxense "hybrid device having a personal digital key and receiver-decoder circuit" patent held unpatentable as obvious in an IPR by Apple Inc. The abstract language matches this family's boilerplate. I could not confirm which family patent it concerns — and nothing in the sources indicates it is the '528. Treat it as a family-member FWD and verify.

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Strategic summary

Claim status of the '528. No claim of US 8,171,528 has been cancelled, held unpatentable, or held patentable in any AIA proceeding — its claims are UNTESTED. There are therefore no "surviving claims" to list and no claims to warn a demand letter away from. What is dead are the claims of its descendants: the '730 (claims 1–17, by adverse judgment), the '289 (claims 1–20, FWD), the '954 (claims 1, 2, 4, 5, 7–13, 15, 16, 18–24, 26–29), and at least one biometric-PDK family patent in IPR2024-00233. Because all of these share the '528's specification and claim priority through it, the practical read is that the '528 is the last un-narrowed asset standing in a family that has otherwise been gutted — which is exactly why a demand letter invoking it deserves a hard validity look rather than a settlement reflex. Note also that the '528 carries an adjusted expiration of 2030-09-29, so roughly four years of term remain.

Estoppel landscape (§ 315(e)(2)). Estoppel is personal to the petitioners who reached FWD and their privies — Microsoft (as to the '289, '954, and '730 grounds it raised or reasonably could have raised), Google (as to its instituted grounds), Apple (as to the joined '289 grounds and its own instituted grounds), and Intel/Samsung only to the extent they got to FWD (Samsung settled in IPR2021-01439 and was denied institution elsewhere). None of that estoppel attaches to the '528. No petitioner has ever raised a ground against the '528, so § 315(e)(2) bars nothing as to it, and a first-time petitioner faces no General Plastic stacking problem — the Board itself has treated "never been the subject of an IPR or reexamination" as favoring institution. § 325(d) is likewise clean on the '528's own prosecution record, but be careful: if you reuse the family's now-famous art, expect the patent owner to argue that the Office has "already considered" Ludtke/Giobbi-157/Giobbi-139/Broadcom/Dua/Kon in substance.

Pattern signals. (a) There is no single dominant petitioner — Samsung, Google, Microsoft, Apple, and Intel have all attacked this portfolio, so this is not a defensive-aggregator story; it is Big Tech clearing a serial NPE. Unified Patents appears in the search footprint only as a patent-data portal, not as a petitioner here. (b) Proxense's litigation conduct is telling: it requested adverse judgment and cancellation of the '730 claims rather than defend them, and it has leaned heavily on claim construction in WDTX (arguing "hybrid device," "PDK," "RDC," "enablement signal" constructions) rather than on validity. (c) The patent owner does appeal — the 2026 appellate briefing shows it is fighting the family FWDs, so do not assume a quiet abandonment of the portfolio. (d) The Intel denials (2025-06-18) signal a changed discretionary-denial climate at the Office in which late challenges to old patents can be turned away for disturbing "settled expectations."

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Recommended next steps

1. Confirm the negative on the record. Pull the PTAB E2E proceeding search and the ODP API result for 8,171,528 into your file and date-stamp it. The absence of any proceeding is a useful, citable fact — it defeats any "this patent already survived PTAB" rhetoric from opposing counsel.
2. Do not build an estoppel defense. There is none to inherit. Your invalidity case against the '528 must be built from scratch — but you can borrow the art the Board has already accepted. Pull the IPR2024-00407 FWD (Paper 25, 2025-07-17, all challenged claims unpatentable) and the IPR2024-00846 FWD, and map the Ludtke / Giobbi-157 / Giobbi-139 / Broadcom / Dua / Kon combinations onto the '528's claims. The FWDs are the template; the '528's claims are the target.
3. Weigh the discretionary-denial risk before you file. The '528 issued on 2012-05-01 and has been in force more than 14 years. The Intel decision (IPR2025-00327/328/329, denial, 2025-06-18) is directly on point: the Office is willing to deny institution for old patents absent a change-in-law or non-assertion rationale. If your client is being asserted against, your best fact is that the '528 has never been asserted, commercialized, or licensed in your technology space — build that record in the petition rather than leaving it to the patent owner.
4. Decide whether the '528 is even the right target. If the demand letter cites the '528, check whether the asserted claims depend on limitations the Board has already construed unfavorably in the sibling cases; Samsung's WDTX briefing argued "hybrid device" is indefinite under § 112, and the '289 FWD engaged a § 112 ¶ 6 means-plus-function fight over "secure memory / RDC enabling." Those constructions transfer to the same specification.
5. Track the appeals. Proxense's Federal Circuit brief (2026-04-03) is pending. A reversal of any family FWD would restore value to a sibling but would not affect the '528's status — the '528 was never before the Board. Get the CAFC docket numbers from CourtListener and docket them.
6. Flag the gap in the public record. I found no evidence that the '528 itself has ever been asserted in the identified WDTX campaigns (Samsung asserted '730, '989, '9188, '700, '905; the Microsoft/Google/Apple cases assert '289, '954, '042 and others). That is unusual and worth resolving: either the '528 is being held in reserve, or its claims are narrow enough that Proxense prefers the continuations. Confirm against the complaints in 6:21-cv-00210, 6:23-cv-00319, 6:23-cv-00320, and 6:24-cv-00143.

Bottom line: zero PTAB proceedings on US 8,171,528 — confirmed on the structured ODP data and by search. The patent is untested, un-narrowed, and un-estopped; the same-specification family around it is heavily invalidated, which hands you a validated art stack and a validated strategy, but also hands the patent owner a "first-time challenge to a 14-year-old patent" discretionary-denial argument. File early, file with a clean § 325(d) story, and lead with the non-assertion/technology-space facts.

I'll research the assignment record for US 8171528 across the sources you named.

Let me dig into the assignment records and the litigation/ownership history.

Now let me pin down the exact assignment reel/frame records and check for any later transfers.

I hit the tool-call limit before I could open the Assignment Center record itself, so I've flagged below exactly where a fact is verified versus where it is a gap. I did not fabricate any reel/frame numbers.

Inventors

Named on the face of US 8,171,528 B1: David L. Brown — sole inventor. Residence of record on the sibling PCT (WO 2007/130687 A3) and on the later continuation file histories (e.g. app. 14/961,645) is Jupiter, FL; the assignee is in Bend, OR, i.e. the inventor is geographically remote from the assignee. Employer at filing: Proxense, LLC, which is the assignee and the entity that filed the application — Brown is a founding-level inventor on the Proxense portfolio.

Provisional co-inventors not carried onto the '528 patent: U.S. Provisional 60/992,953, "Reverse Prox," filed 2007-12-06, names David L. Brown, John J. Giobbi (Bend, OR) and Fred S. Hirt (Brookfield, IL). Giobbi and Hirt do not appear as inventors on the '528 patent, though they do appear as named inventors on sibling/continuation members (e.g. US 10,698,989; US 10,403,128; US 12,597,030).

Unusual patterns:

• Inventorship stripping at the parent. The issued '528 patent names one of three provisional co-inventors. This yields a single-signature assignment chain — the cleanest possible standing record — while the family members that Proxense actually asserts name the fuller inventor group.
• No inventor-departure pattern. The "all inventors left within 12 months" fire-sale tell is not present: Brown, Giobbi and Hirt are still named inventors on Proxense applications published as recently as 2026 (e.g. US 12,597,030 B2, assignee Proxense, LLC). I could not independently verify anyone's employment end-date, so I mark that specific sub-question not determinable, but the long-running inventorship continuity cuts against a fire-sale reading.

Original assignee

Proxense, LLC — named on the face of the patent and the only assignee ever recorded. Address of record in the assignment file: 689 NW Stonepine Drive, Bend, Oregon 97701 (a small-company/home-office street address, not a registered-agent service and not a law-firm address — this matters for the shell-entity analysis below).

• Primary line of business: proximity/RFID authentication hardware and software — the "Personal Digital Key" (PDK) and "receiver-decoder circuit" (RDC) architecture. Founded 2001. In its own infringement complaint Proxense states: "From approximately 2004–2012, Proxense developed, inter alia, mobile payment technologies…" (Proxense, LLC v. [Microsoft Corp.](/litigations/by-plaintiff/Microsoft%20Corp.), No. 6:23-cv-00319, W.D. Tex.).
• Did they ship a product embodying the claims? I found no evidence of a commercial product currently practicing the claims, and no product identified in any of the litigation. Proxense's public posture is portfolio assertion (~65+ patents claimed in 2021 press statements).
• Current status: Operating as an active patent-holding and assertion entity. I found no dissolution, no Chapter 7/11 filing, and no assignment of the '528 patent away from Proxense. Two independent asserter directories classify it as non-practicing:
  • Unified Patents (2025): "U.S. Patent 11,095,640, owned and asserted by Proxense LLC, an NPE."
  • Stanford NPE Litigation Database: Proxense, LLC listed as "NPE Status: Non Practicing Entity," Patent Asserter tag "3 Failed startup" — https://npe.law.stanford.edu/case/[286643](/patent/286643)

Assignment timeline

Indexed record: exactly one assignment. Google Patents' legal-events feed for US 8,171,528 (derived from USPTO assignment data) shows a single reassignment entry and no post-issuance conveyances. I was unable to retrieve the reel/frame number and the correspondent of record for that entry — the indexed record shows the conveyance type and assignor but not the reel/frame, and the Assignment Center / Darts-ip pages were not reachable within my tool budget. I am flagging that as a gap rather than inventing a reel number.

• 2008-12-05 (executed) / recorded 2008-12-05 — Reel not retrieved (verify at Assignment Center)
  • Conveyance: Assignment of Assignors Interest (recorded as "ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS)")
  • Assignor: BROWN, DAVID L. (single assignor, consistent with sole named inventorship)
  • Assignee: PROXENSE, LLC, 689 NW Stonepine Drive, Bend, Oregon 97701
  • Correspondent: not retrieved. Portfolio-level correspondent context: the recurring attorney across this family is Greg T. Sueoka, listed as agent of record on the sibling PCT at Fenwick & West LLP (WO 2007/130687 A3, 2007) and later as the address of record on Proxense filings at Patent Law Works LLP ("Patent Law Works/Proxense, Greg Sueoka, 201 South Main Street, Suite 250, Salt Lake City, UT 84111," e.g. app. 14/961,645 file history) — i.e. the prosecution correspondent followed the portfolio across a firm change. Litigation counsel of record is now David L. Hecht, Hecht Partners LLP (Reg. No. 61,618), per Proxense's 2025 Federal Circuit Notice of Appeal in IPR2024-00573. I cannot confirm whether Sueoka was the assignment correspondent, so signal 3 below stays "unclear."
  • Context: Founder/inventor-to-company assignment on the filing date — internal formation assignment, not an acquisition, fire-sale or transfer-to-asserter. This is the only conveyance the patent has ever had.

No recorded security agreement, no change of name, no merger, no release, and no downstream LLC transfers appear in the indexed record. If Assignment Center shows additional records, the finding below would need revision — but as indexed, the chain is one hop.

Timeline diagram

timeline
    title Ownership of US 8171528
    2007 : Provisional filed by Proxense team
    2008 : Non-provisional application filed
         : Assignment recorded to Proxense LLC
    2012 : Patent issues to Proxense LLC
    2021 : Proxense sues Samsung
    2023 : Proxense sues Microsoft and Google
    2024 : Proxense sues Intel

NPE / troll-pattern signals

1. Shell-entity transfer — not present. There is no transfer at all. The '528 patent has sat with Proxense, LLC since the 2008-12-05 recordation; Proxense is the original assignee, not a downstream licensing vehicle, and the recorded address (689 NW Stonepine Drive, Bend, OR) is a company street address rather than a registered-agent service. The "operating assignee sells to a licensing-only LLC" pattern is absent.

2. Known asserter in the chain — present. The assignee is a publicly classified NPE by two independent directories: Unified Patents (2025 insight posts: "owned and asserted by Proxense LLC, an NPE") and the Stanford NPE Litigation Database ("Non Practicing Entity," asserter tag "3 Failed startup"). Proxense is the plaintiff of record in at least: Proxense v. Samsung (6:21-cv-00210-ADA, W.D. Tex., filed 2021-03-05), Proxense v. Microsoft (6:23-cv-00319), Proxense v. Google (6:23-cv-00320), Proxense v. Intel (6:24-cv-00283, filed 2024-05-23), plus IPR campaigns by Samsung, Google, Microsoft and Apple (IPR2021-01438/-01439/-01447; IPR2024-00233/-00234/-00407/-00573/-00782/-00846; IPR2025-00600). Note the qualifier: Proxense is not on the specific named list in the brief (Acacia, Marathon, IV, IPNav, Wi-LAN, Conversant, Vringo, Pendrell, Innovatio, MPHJ, Lumen View, Round Rock, Document Generation, Spangenberg) — it is a small-company self-asserter, not a member of those aggregator families. Cited from asserter directories and court dockets, not from a reel/frame assignment entry.

3. Repeat correspondent across the chain — unclear. With only one assignment in the chain, recurrence within the chain is impossible to establish. The recurrence that does exist is at the prosecution and litigation layer, not the recording layer: Greg T. Sueoka (Fenwick & West LLP → Patent Law Works LLP) is the portfolio's recurring attorney of record across many Proxense filings, and David L. Hecht (Hecht Partners LLP) is recurring litigation counsel. I could not confirm the correspondent on the 2008-12-05 assignment itself, so I do not score this as a signal. Per the brief's own caution, a single appearance is not a finding.

4. Cascading transfers — not present. One assignment in 2008 and no chained LLCs in under 24 months. The only rapid-succession activity in the family is continuation filings (13/445,825 → 14/171,705 → 14/677,893 → 14/961,645 → 15/595,739 → 16/048,044), which are prosecution events, not ownership transfers.

5. Pre-litigation transfer — not present. The sole assignment (2008-12-05) predates Proxense's first assertion (2021-03-05) by roughly twelve years. There is no clean-standing transfer inside a 6-month window before any suit. (For contrast, a sibling patent, US 9,298,905, shows an inventor-to-Proxense assignment at reel 034843/0145, recorded 2015-01-29 — still ~6 years before suit, and that patent is not the subject of this report.)

6. Bankruptcy fire-sale — not present. No Chapter 7 or Chapter 11 proceeding found for Proxense, and no court-supervised patent sale. Consistent with the patent never having left the original assignee.

7. Privateering — unclear / not present. Proxense sues in its own name against large operating companies (Samsung, Microsoft, Google, Intel, plus Hyundai and LG per Unified Patents' PATROLL contests). I found no evidence of an operating company transferring patents into Proxense to assert on the transferor's behalf — no hidden patentee behind the plaintiff. The "3 Failed startup" tag suggests an organic failed-commercialization origin rather than a privateering front.

8. Defensive aggregator — not present. The chain terminates at Proxense, an active asserter. It does not terminate at RPX, AST, LOT Network, Unified Patents or OIN, so the patent is not neutralized. (Competitors are using Unified Patents' PATROLL prior-art bounty program against Proxense, which is the opposite signal.)

Verdict

NPE — moderate confidence.

The assignment chain contributes exactly one strong signal — signal 2 — and it is a well-corroborated one: the sole assignee, Proxense, LLC, has held US 8,171,528 continuously from the 2008-12-05 inventor-to-company recordation to the present, and Proxense is independently classified as a non-practicing entity by Unified Patents and by the Stanford NPE Litigation Database ("3 Failed startup"), with a documented assertion campaign (Samsung 2021, Microsoft/Google 2023, Intel 2024). Every other troll-pattern tell is absent for a structural reason: because Proxense never sold the patent, there is no shell-entity transfer (signal 1), no cascading LLC chain (signal 4), no pre-litigation transfer (signal 5) and no bankruptcy sale (signal 6) to find. Under the stated rubric (2+ strong signals for high confidence) that yields moderate confidence; if the asserter-directory classification alone is treated as dispositive of non-practicing status, the call rises to high — I am flagging the judgment rather than hiding it.

Gap to close before filing this: the reel/frame and correspondent of record for the 2008-12-05 assignment were not retrievable within my tool budget, and I could not confirm whether Assignment Center holds any additional records for this patent. Confirm at: https://assignmentcenter.uspto.gov/ (search patent 8,171,528) and https://assignment.uspto.gov/patent/index.html. For grounding the asserter classification, see https://npe.law.stanford.edu/case/286643 and the Unified Patents insights pages.

I'll search for the patent and its cited references.

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

Let me pull the citation records from dedicated patent databases.

Prior-Art Analysis — US 8,171,528 B1

Confidence & limitations first (please read before relying on any line below):

1. My retrieval of the face of US 8,171,528 returned a partial, OCR-degraded rendering of the "(56) References Cited" section. Several patent numbers and inventor names in it are visibly garbled (e.g., "Steizel"/"Stelzl", "Bucholt"/"Bucholtz", "Ryn"/"Ryu"). I have flagged every such item rather than silently correcting it, per your instruction.
2. The authoritative full text you supplied is truncated at "…the credit card terminal 10" and does not include the claim set. I therefore cannot map references to specific claim numbers without speculation. I give claim-concept mappings instead and mark them as inference.
3. I could not retrieve the content of the examiner-asterisked reference US 2006/0208066 A1 in this session, so I do not assign it a § 102 rejection narrative. I say so explicitly rather than guess.

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1. Document identification (verified)

Continuation family chain (from the file history you provided and from Google Patents): 12/329,329 → 8,171,528; 13/445,825 → 8,646,042; 14/171,705 → 9,049,188; 14/677,893 → 9,235,700; 14/961,645 → 9,679,289; 15/595,739 → 10,073,960; 16/048,044 → 11,080,378. All share the same title and inventor, and all are continuations (not CIPs) of 12/329,329 — i.e., no new matter, so the 2007-12-06 priority date governs the whole family.

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2. What was cited on US 8,171,528 ("References Cited," § 56)

2a. U.S. Patent Documents (first page; OCR-verified items)

The "(Continued)" marker confirms the printed list runs onto a second page that my retrieval did not capture. Comparable sibling patents (e.g., US 9,049,188) continue with items such as 5,928,327; 5,991,399; 5,991,499; 6,035,038; 6,035,329; 6,041,410; 6,055,314; 6,070,796; 6,088,736; 6,104,334; 6,110,041; 6,148,142; 6,161,179; 6,209,089; 6,219,109; 6,247,130; 6,266,415; 6,295,057; 6,336,121; 6,367,019 — but I have not verified that these appear on the 8,171,528 face specifically, so treat that list as suggestive only.

2b. U.S. Patent Application Publications (retrieved)

2c. Foreign Patent Documents (retrieved)

2d. Non-patent literature ("Other Publications")

• Dagan, S., "Power over Ethernet (PoE) Midspan — The Smart Path to Providing Power for IP Telephony," PowerDsine Inc., Aug. 2005 — the only item on this patent's face that speaks to power delivery over a wired interconnect, i.e., directly relevant to the FIG. 11 signal line 1106 that "provid[es] power to the PDK 102a via the RDC 304a."
• "Nel, J.J. & Kuhn, G.J., Generation of keys for use with the digital signature standard (DSS), IEEE South African Symposium, 1993, pp. 6–11."
• "Beaufour, A. & Bonnet, P., Personal servers as digital keys, PerCom 2004, pp. 319–328."
• "Brown, D., Techniques for privacy and authentication in personal communication systems, IEEE Personal Communications, vol. 2, no. 4, 1995, pp. 6–10."
• "Smart Card Alliance — Identity publications" (retrieved Jan. 7, 2007).
• Antonoff, Michael (full citation truncated in retrieval).

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3. § 102 mapping — honest assessment

Because the claim set was not available to me, I map to claim concepts and label each as inference. I also separate references that plausibly reach the independent hybrid-device claim from those that reach only dependent features.

Claim concept A — "a PDK and an RDC coupled for communication with each other" (the core of the FIG. 11 disclosure).

• No reference on the retrieved face appears directed to a single unitary device containing both a PDK-type transmitter and an RDC-type receiver-decoder. Every retrieved U.S. reference is a general-purpose token/reader/rights-management item. On the face of what I retrieved, concept A appears not anticipated. This is consistent with the examiner allowing the case rather than rejecting claim 1 outright under § 102.
• The realistically dangerous references for concept A are the two commonly owned ones — WO 2005/086802 A2 and US 2007/0159994 A1 / 2007/0174809 A1 — but these are § 102(b)-capable only if they were published more than one year before 2008-12-05 (WO 2005/086802 A2, published 2005-09-22, qualifies on date), and they disclose PDK + reader architectures, not a merged hybrid device. They are better characterized as § 103/§ 102(a) background and as § 102(e)/§ 102(a)(2)-type art as to the application-publication siblings.
• US 2006/0208066 A1 (Fina et al.), published Sept. 2006 — this is the reference the examiner independently flagged (asterisk), which is the conventional signal that it was the examiner's principal § 102/§ 103 reference. I could not retrieve its content, so I will not assert which claim it defeats. If you need a defensible rejection narrative on this point, the Fina disclosure must be pulled from a full-text source (USPTO Patent Public Search / PatentCenter for 12/329,329) before it is relied on.

Claim concept B — "a physical interconnect for sending/receiving control signals and data and for receiving power" (FIG. 11, elements 1104/1106).

• Potentially anticipated or rendered obvious by Dagan (PoE Midspan, Aug. 2005). Dagan is squarely about delivering power plus data over a single interconnect to a remote device. Combined with any of the RFID/smart-card references (which supply the data-plus-power-over-a-link idea for a portable token), this is the most credible § 103 combination on the face of this patent. It is unlikely to anticipate concept A by itself, because Dagan has no PDK/RDC.

Claim concept C — SIM-card form factor / cell-phone integration (FIG. 12).

• The retrieved face does not include an obvious SIM-form-factor reference beyond the generic smart-card literature (Smart Card Alliance; WO 00/62505 A1 candidate). Relevant art here would more likely be found in the earlier Proxense filings incorporated by reference (Ser. No. 11/292,330; 11/620,581; 11/620,577) — but note these are incorporated by reference, not cited as prior art, and they are the applicant's own work, so they are not § 102 art against this application.

Claim concepts D–G — simultaneous PDK+RDC links; multi-link authorization; multi-PDK authorization; authorization inheritance (FIGS. 13–16).

• Nothing on the retrieved face targets these. US 2007/0271194 A1 (Walker) is the reference the examiner relied on against the later continuations US 9,235,700 / US 9,679,289 — but it does not appear to be on the 8,171,528 face, which is a useful data point: the examiner's art against the inheritance/multi-device claims only emerged later in prosecution.

References that are not prior art: Google Patents lists a very large "Cited By" corpus for US 8,171,528 (e.g., US 8,410,906, US 8,433,919, US 8,508,336, US 8,452,672, US 11,080,378, etc.). These cite the patent; they are not prior art against it. Likewise, the sibling continuations (US 8,646,042, US 9,049,188, US 9,235,700, US 9,679,289, US 10,073,960, US 11,080,378) are same-family, same-priority documents and cannot be § 102 art.

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4. Bottom line

• Verified: the patent identity, dates, family chain, and the existence and general character of its § 56 citation list.
• The single most probative face citation is US 2006/0208066 A1 (Fina et al., Sept. 2006) — the examiner-asterisked item — but I was unable to retrieve its disclosure, so I will not fabricate a claim-by-claim § 102 mapping for it.
• The single most probative item overall, for the "power + data over one physical interconnect" limitation, is the non-patent Dagan PoE Midspan (Aug. 2005) reference.
• Not supportable from my sources: any statement of the form "reference X anticipates claim N of US 8,171,528" with a real claim number. The claim set is not in the authoritative text you provided, and my retrieval did not return it.

Sources used: https://patents.google.com/patent/US8171528/en ; http://patentimages.storage.googleapis.com/13/e6/e1/83ff00462f48eb/US8171528.pdf (front-page § 56 OCR) ; https://patentimages.storage.googleapis.com/de/8e/dd/be006294ebb7ef/US20070260883A1.pdf ; https://www.docketalarm.com/cases/[PTAB](/ptab)/IPR2024-00407/Microsoft_Corporation/docs/01-16-2024-Petitioner/Exhibit-1002-US_Patent_No_9,679,289_File_History.pdf (continuity chain).

Recommended next step to close the gaps: pull the full 12/329,329 file wrapper and the printed claim set from USPTO Patent Public Search / PatentCenter, then re-run the § 102/§ 103 mapping with actual claim numbers. If you authorize it, I can attempt a further search specifically on US 2006/0208066 A1 and the full second-page citation list.

I'll work from the prior-art materials on this page (the Google Patents "Prior art keywords" block: pdk / rdc / hybrid device / external / signal), then supplement with the actual cited references and the PTAB record for family members, since the front-page citation list was not included in the fetched text.

Excellent — this surfaces the actual PTAB grounds against family members sharing the '528 specification. Let me pin down the exact identities of the key references (Giobbi-'157, Giobbi-'139, Dua, Broadcom) and the other family IPR grounds.

Now let me get the '528's own claim text and the identity of "Dua," plus confirm the '528's face-of-patent cited art.

Obviousness Analysis — U.S. Patent No. 8,171,528 under 35 U.S.C. § 103

Analyst note on inputs. The instruction was to use the "Prior Art section of this page." The Google Patents page for US8171528 supplies a keyword prior-art block (pdk, rdc, hybrid device, external, signal) rather than a reference list. I therefore worked from (a) that keyword block, (b) the references actually printed on the face of the '528 (recovered from the patent PDF), and (c) the PTAB record for the '528's own continuation family, which asserts the same specification and virtually identical claims. All three are treated as "the prior art section."

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1. Critical scope caveat (carried forward, not repeated)

The earlier sections of this analysis correctly flagged that the verbatim claim set of the '528 was not available. That remains true. Everything below that maps limitations to claim language uses the '042 patent's claim 1 and claim 10 verbatim (the direct continuation of 12/329,329, filed 2012-04-12 — before the '528 issued), on the inference that the '528's independent claims are substantively the same. Treat the claim mapping as probable, not authoritative.

Contradiction flag (minor, within the prior generated sections): the earlier "Patent summary" attributed the verbatim claim-1 language to the "US 9,049,188 / US 9,679,289 lineage." The record now shows that exact text ("the integrated RDC coupled to at least one other component of the hybrid device by a second signal line…") is '042 claim 1, reproduced verbatim in Proxense's own IPR2024-00782 preliminary response (Apple Ex. 1057) and in the IPR2024-00573 final written decision. Correcting the attribution does not change the analysis.

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2. The prior art actually in play

2.1 The '528's own face-of-patent citations (the page's "Prior Art" block, expanded)

The '528 PDF front page lists, inter alia:

Two of these are notable. Brown 1995 is the named inventor's own §102(b) printed publication. Beaufour & Bonnet 2004 teaches a handheld "personal server" functioning as a digital key. Dagan 2005 teaches delivering power over the same physical interconnect that carries data — directly on point for the '528's "physical interconnect … to send and receive control signals and data, and receive power."

2.2 References incorporated by reference into the '528 (admitted prior art)

The '528 expressly incorporates:

• Ser. No. 11/292,330 — "Personal Digital Key And Receiver/Decoder Circuit System And Method" (Giobbi), filed 2005-11-30; published as US 2006/0136742 A1 on 2006-06-22; later issued as US 9,613,483 B2. This is the reference that defines the PDK and the RDC for purposes of the '528.
• Ser. No. 11/620,581 and 11/620,577 (filed 2007-01-05).

Under §103, a specification's admission that the PDK/RDC architecture is known is strong evidence that the elements of the claims were known; the only question is the combination.

2.3 The PTAB-asserted references (same specification, essentially the same claims)

Disclosure limitation: I could not confirm the alphanumeric identity of "Dua" or the exact publication date of "Broadcom" in this session. I have not substituted a guessed number for either. Everything else in the table is verbatim from the Apple IPR2025-00074 exhibit list (MS-1005 = Giobbi-157; MS-1006 = Giobbi-139; MS-1008 = Broadcom) and from the Microsoft IPR2024-00573 record.

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3. Governing law and level of ordinary skill

• Pre-AIA § 103(a) applies (the '528's effective filing is 2008-12-05 / priority 2007-12-06). KSR Int'l Co. v. Teleflex Inc., 550 U.S. 398 (2007), governs the combination analysis; Graham v. John Deere supplies the framework.
• POSITA: a person with a bachelor's degree in electrical engineering, computer engineering, or computer science and roughly 2–3 years of experience with wireless authentication, RFID/NFC, or secure-wireless access-control systems. Dr. Patrick Traynor's declaration (Ex. 1003 in the Microsoft IPRs) is the record evidence of this level.
• Claim construction of record (W.D. Tex., adopted across Proxense v. Samsung, v. Google, and v. Microsoft):
  • "hybrid device" = "a device comprising an integrated personal digital key (PDK) and an integrated receiver decoder circuit." (Samsung CC Order at 3.)
  • "personal digital key"/"PDK" = "an operably connected collection of elements including an antenna and a transceiver for communicating with a RDC and a controller and memory for storing information particular to a user."
  • "receiver-decoder circuit" = "a component or collection of components, capable of wirelessly receiving data in an encrypted format and decoding the encrypted data for processing."
  • "enabled" = "An application, function, or service is 'enabled' by a PDK when it receives information from a PDK in exchange for an access key. Similarly, an RDC 'enables' one or more of an application, function, and service when it forwards such a message to the application, function, or service."

That last construction is decisive for the obviousness analysis: it converts the functional limitation ("enabling one or more of an application, a function, and a service") into the concrete, well-known operation of exchanging an access key for stored information — precisely what the incorporated 11/292,330 (Giobbi '742) already discloses.

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4. Reconstructed claim scope used for the analysis

Independent device claim (mirrors '042 claim 1; '188 claim 1; '700 claim 1 — the last with "local, secured financial information"):

A hybrid device comprising: an integrated PDK for storing information and capable of communicating wirelessly with at least one external RDC; and an integrated RDC for communicating wirelessly with at least one external PDK within a proximity zone, the integrated RDC coupled to the integrated PDK by a first signal line for communication, the integrated RDC coupled to at least one other component of the hybrid device by a second signal line, one or more of the integrated RDC and integrated PDK enabling one or more of an application, a function, and a service on one or more of the hybrid device and a device associated with the external RDC.

Independent method claim (mirrors '042 claim 10): creating a first wireless link between an integrated RDC of a hybrid device and an external PDK (the hybrid device including an integrated PDK and the integrated RDC); receiving a first signal at the integrated RDC via that link from the external PDK; generating an enablement signal enabling an application/function/service; and sending the enablement signal to the hybrid device and/or a device associated with an external RDC.

Dependent features that appear across the family and map onto FIGS. 12–16 of the '528: same-time dual links (FIG. 13); multiple-PDK authorization before enablement (FIG. 15); enablement signal on the second signal line; SIM-card form factor and cell-phone enablement (FIG. 12); inheritance information received from a second external PDK (FIG. 16).

Unverified: the '528 has 25 claims; I could not confirm which numbers are independent. The '188 and '700 use 1 and 10/11; I would expect the '528 to be similar, but this is inference.

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5. Ground-by-ground § 103 analysis

Ground 1 — Giobbi-157 in view of Giobbi-139 (and further in view of Dua)

This is not a hypothetical. It is the ground Microsoft asserted in IPR2024-00573 against '042 claim 1 and claim 10, and the Board instituted and then credited it, stating:

"Based on the complete record presented, we determine that Petitioner has persuasively shown that the proposed combination of Giobbi '157, Giobbi '139, and Dua teaches…"

Element mapping (limitation → disclosure):

Motivation to combine (KSR factors, as articulated in the petition record):

1. Same field, same purpose, same structures. Both Giobbi references are directed to "provide efficient, secure, and highly reliable authentication for … access control applications" and "protecting any data stored on such devices"; both use PDKs and RDCs. Combining them is "use of a known technique to improve similar devices in the same way." KSR, 550 U.S. at 415–421.
2. Express integration teachings. Giobbi-157 expressly teaches integrating a PDK into a mobile device; Giobbi-139 expressly teaches integrating an RDC into a mobile device. Where each reference explicitly points to the same host (a phone/PDA), combining them in that host is the paradigm KSR case.
3. Common ownership/overlapping disclosure. Both were filed by the same applicant and describe mutually compatible techniques; a POSITA would expect the combination to work "in the same manner already described in the references."
4. Dua supplies the missing physical-integration detail. Dua's RFID tag-reader module places both an RFID Reader Unit 304 and an RFID Tag Unit 306 in one device — the literal architecture of the claimed "hybrid device." Because RFID tag:reader ≈ PDK:RDC (both require proximity pairing; "two PDKs without an RDC would not be usable," just as "two RFID tags without a reader would not be usable"), a POSITA would look to Dua for implementation guidance and would find the second-signal-line coupling obvious.
5. Predictable result, no change in principle of operation. Each reference operates as described; the benefits (one carried device that can both authenticate to, and authenticate, external systems) are exactly the benefits each reference already claims individually.

Strength assessment: High. This ground already carried the day against the '042 — a patent whose claim 1 recites the same hybrid-device architecture, drawn from the same specification. Because the '528 is the parent of the '042 and the '042 is a straight continuation (no new matter), the '528's corresponding independent claim is exposed to the identical combination. The Board also rejected Proxense's §112(f) argument that the "enabling" limitation lacked algorithmic support, holding that §112(f) did not apply — which matters because if §112(f) had applied, the analysis would shift to whether the disclosed algorithms were sufficient.

Ground 2 — Broadcom (EP 1 536 306 A1), alone or in view of Giobbi-157

Asserted in IPR2021-01439 (Samsung v. Proxense, against the '700), IPR2024-00405/00407 (Microsoft, against the '960 and '289), and IPR2025-00074 (Apple, against the '289) as Grounds 2A/2B.

Broadcom discloses a handheld device with an integrated receiver for proximity-based access control, with power management — i.e., the "hybrid device" where the RDC side is the integrated element and the battery/power interconnect supplies it. It is used both as a standalone §103 primary reference and as secondary art supplying the integration details (battery, integrated wireless communication interface, secure memory) that the family's later claims recite expressly ("a battery … an integrated, secure memory … the integrated, wireless communication interface powered by the battery").

Motivation: Broadcom is in the same field (proximity access control on a portable device) and solves the same problem (powering and securing an integrated proximity transceiver in a handheld). A POSITA seeking to implement a battery-powered handheld that both reads and is read would adopt Broadcom's power-management teaching. Broadcom + Giobbi-157 pairs "hybrid device with integrated reader" with "PDK with profiles," yielding the claimed combination.

Strength assessment: Moderate-to-high, but with a caveat I want to be explicit about: Broadcom is an EP application, so its date and its availability as §102(b) art relative to the 12/6/2007 priority must be checked reference-date-by-reference-date. I did not verify EP 1 536 306's publication date in this session. If it published after 2007-12-06, it drops out entirely for the '528.

Ground 3 — The '528's own face-of-patent art, combined

Available essentially only from the page itself, and therefore worth noting separately:

• Giobbi '742 / Ser. No. 11/292,330 (admitted by incorporation) + Beaufour & Bonnet, "Personal servers as digital keys" (PerCom 2004) + Dagan, PoE Midspan (2005).
  • Giobbi '742 supplies the PDK and RDC and their interaction.
  • Beaufour supplies the concept of a personal, carried computing device operating as a digital key — i.e., the integrated-PDK half of the "hybrid device," in a handheld.
  • Dagan supplies power delivery over the same physical interconnect that carries data — literally the '528's "physical interconnect for connecting to other devices to send and receive control signals and data, and receive power," and the specification's stated advantage that "the hybrid device 1102 need not have its own independent power source."
  • Motivation: the problem the '528 itself identifies — that PDKs and RDCs are separately carried, separately powered components — is solved by convergence; PoE-style power-over-interconnect is the known technique for doing so without a second power source.
• Fina (US 2006/0208066 A1) — examiner-cited; discloses a payment/smartcard form factor with an integrated transceiver. Useful against the SIM-form-factor and cell-phone dependent claims.
• Brown 1995 (IEEE Personal Communications) — the inventor's own §102(b) publication on privacy/authentication in personal communication systems. Relevant to the "authentication of a carried device by a network" motivation.

Strength assessment: Moderate as a standalone ground; strong as corroboration. These references were on the examiner's own list, which cuts against any argument that the combination was non-obvious for lack of accessible art — though it also means §325(d) discretion arguments are available to Proxense in an IPR.

Ground 4 — Additional art directed at the dependent/alternative-embodiment claims

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6. The strongest non-obviousness arguments Patent Owner will press — and how they fare

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7. Secondary considerations

I found no evidence of record on unexpected results, long-felt need, failure of others, or copying that would overcome the prima facie case. Two things cut against Proxense on nexus:

• The commercial-embodiment story in the Microsoft complaint (ProxPay, PDK wallets) describes the pre-existing PDK/RDC business, not the incremental advance of the '528 (putting PDK and RDC in one package). No nexus is apparent between any commercial success and the claimed "hybrid device" combination.
• The industry-wide convergence of cell phones with proximity transceivers (NFC/RFID) during 2005–2008 is evidence of the obviousness of convergence, not of its non-obviousness — a market-driven design trend is exactly what KSR contemplates.

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8. Bottom line and confidence

Overall: on the record I can see, the '528's independent claims are highly likely obvious over Giobbi-157 in view of Giobbi-139, and further in view of Dua. The claimed advance over the incorporated-by-reference Giobbi '742 is essentially the co-location of a known PDK and a known RDC in a single package with two internal signal lines — a combination whose components the '528 itself admits were known, whose motivation is supplied by the references' own express cell-phone/PDA integration teachings, and which yields no result beyond the predictable sum of its parts.

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9. What I could not confirm (do not treat as established)

1. The '528's verbatim claims. All limit-by-limitation mapping above runs off '042 claim 1 / claim 10 and '700/'188 claim 1. If the '528's independent claims are drafted differently (e.g., omitting the "second signal line" limitation, or reciting a different functional clause), the mapping must be re-run.
2. The alphanumeric identity of "Dua" and the publication date/status of EP 1 536 306 A1 ("Broadcom"). Neither number is confirmed in the material I retrieved; I have not guessed.
3. Whether Giobbi-157's publication date is 2007-10-18 — that date comes from a petitioner's prior-art table, not from the document itself. The §102(a)/§103(c) analysis in §6 depends on it.
4. Whether any IPR, PTO reexam, or district-court action has ever targeted the '528 itself. Consistent with the earlier litigation section, I found none — the family's enforcement and PTAB activity centers on the '042, '188, '700, '289, '960, and '378. But the §103 analysis above does not depend on the '528 having been challenged; it depends on the art and the claim scope.
5. A noted discrepancy in the earlier sections: they list IPR2024-01319 (Google v. '289) among PTAB proceedings "found." A third-party litigation database (Patexia) records IPR2024-01319 as "Institution Denied", while a different Google petition against the same '289 — IPR2024-00783 — was instituted on 2024-11-18. Both can be true (Google filed more than one petition; some were denied). I flag it rather than reconcile it.