Invalidity dossier
US 5940375
Added 9/23/2026, 5:06:46 PM
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Patent summary
Title, assignee, inventors, filing/issue dates, abstract, and a plain-language overview of the claims.
Patent Overview: US5940375A
Title: Feedback control apparatus and cell scheduling apparatus for use with cell exchange
Patent number: US5940375A (application US08/829,171)
Assignee: Fujitsu Ltd (original and current assignee, per the source listing)
Inventors: Toshio Soumiya, Koji Nakamichi, Naotoshi Watanabe, Takeshi Kawasaki
Key dates: Prior art date 1996-10-31; filing date 1997-03-31; granted/publication date 1999-08-17; anticipated expiration 2017-03-31. Legal status: Expired – Fee Related. The source notes legal status is an assumption, not a legal conclusion.
Purpose: The invention concerns averting network congestion using feedback control in conjunction with the ATM ABR (available bit rate) service. In ABR, an exchange monitors network resource use and dynamically signals a source end system so its transmission rate varies between a peak cell rate (PCR) and a minimum cell rate (MCR), avoiding congestion and cell loss.
Plain-language scope: Resource management (RM) cells carry network resource information. A source end system normally sends one RM cell per a predetermined number of user data cells; RM cells traverse the ATM network to a destination end system and loop back, with ATM exchanges writing bandwidth/congestion information into them. The source recalculates its allowed cell rate (ACR), bounded by MCR ≤ ACR ≤ PCR. The description covers EFCI mode and ER mode, congestion indicator (CI) and EFCI bits, explicit rate (ER) comparison, and exchange- or destination-generated RM cells. It further describes ABR VS/VD (virtual source/virtual destination) functions, which let an ATM exchange generate, loop back, and terminate RM cells internally, segmenting one control loop into multiple parallel feedback loops for faster response. The feedback control apparatus for a cell exchange comprises virtual destination-link means, virtual source-link means, virtual source-internal means, and virtual destination-internal means. An "out-rate RM" cell is also defined.
Source: https://patents.google.com/patent/[US5940375](/patent/US5940375)/en
What the excerpt does not establish: The supplied text is explicitly an excerpt. It does not provide the full claims, complete detailed description, drawings, the cell scheduling apparatus details, or the full text of the recited means (e.g., VD-L 305). No litigation, ownership transfer, validity, or prior-art analysis is included or asserted here.
Generated 10/1/2026, 9:43:51 PM
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Litigation summary
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PTAB challenges
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Assignment history
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Prior art
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Obviousness
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Extensions
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Derivative works
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