Invalidity dossier
US 5257257
Method of controlling the operation of a packet switched CDMA communication network for controlling the operation of transmitters and receivers
Current assignee: Nokia Solutions and Networks Oy
Added 9/21/2026, 9:31:48 AM
Active provider: DeepSeek · deepseek-flash
Patent summary
Title, assignee, inventors, filing/issue dates, abstract, and a plain-language overview of the claims.
Patent Overview — US 5257257 A
Title: Method of controlling the operation of a packet switched CDMA communication network for controlling the operation of transmitters and receivers.
Patent number / application: US5257257A; application US07/863,026, filed 1992-04-03; granted/publication date 1993-10-26.
Priority date: 1991-04-05 (listed as an assumption, not a legal conclusion).
Inventors: Xiao H. Chen and Juhani Oksman.
Original assignee: Nokia Mobile Phones Ltd. The source also lists a current assignee (Nokia Solutions and Networks Oy) and later reassignments; legal status is listed as "Expired - Lifetime" with anticipated expiration 2012-04-03.
Purpose: To control operation of transmitters and receivers in a packet switched CDMA network, avoiding problems of prior protocols such as channel load sensing (described as "blind"), CSMA, and BTMA, which the patent says suit narrowband networks and cannot detect simultaneous CDMA packet transmissions. The stated advantages include throughput up to about 0.57 (about 50% above the best conventional R-T spreading code), fewer collisions, shorter delays, reduced channel backlogs, and improved network stability.
Plain-language scope: In a network where each of N users' terminals has an assigned substantially orthogonal receiver code (used by others to address/encode packets to that terminal) and an assigned transmitter code (used by the terminal itself to encode packets to others), a terminal wanting to transmit senses the channel for the receiver code or transmitter code of the intended receiving terminal to determine whether that receiver/transmitter is busy. The method uses a protocol identifying receiver and transmitter codes by channel sensing, with handshaking via different packet types (request, acknowledgement, data). Claim 1 characterizes the transmitter-control method and claim 5 the receiver-control method; the excerpt does not set out their full wording.
Not established by this excerpt: The complete text of claims 1 and 5; the detailed flow-chart logic and omitted description; the exact figures/data values beyond those quoted; and the full prosecution or assignment history. No litigation, validity, ownership, or prior-art analysis is made here.
Generated 10/1/2026, 10:02:14 PM
Cases on file (0)
Specific litigation cases in our database that name US patent 5257257. The free-form analysis below may also discuss cases beyond this list.
No cases on file mention this patent. Upload a CSV or add a case manually in Admin → Manage litigation cases.
Litigation summary
Past and pending lawsuits — plaintiffs, defendants, jurisdictions, outcomes, and notable rulings.
Proceedings on file (0)
All PTAB activity →AIA trial proceedings (IPR / PGR / CBM) filed at the USPTO Patent Trial and Appeal Board against this patent. Sourced from the USPTO Open Data Portal and refreshed every six hours; each proceeding number deep-links to the PTAB E2E docket.
No PTAB proceedings on file. This patent has not been challenged via IPR, PGR, or CBM. The absence is itself a signal — well-asserted patents eventually attract IPRs. The LLM analysis below may surface filings the ODP feed hasn’t indexed yet.
PTAB challenges
AIA trial proceedings at the USPTO Patent Trial and Appeal Board — IPR, PGR, and CBM. Petitioners, judge panels, claim-level invalidation outcomes from Final Written Decisions, and Federal Circuit appeals. The single most important defensive datapoint after litigation history.
Assignment history
Inventors, original assignee, and the chain of ownership recorded with the USPTO — including the correspondent attorney who recorded each assignment, since shell-LLC chains often share one repeat-player attorney even when the entity names look unrelated. Surfaces NPE / patent-troll patterns: shell-entity transfers, known asserters in the chain, repeat correspondent fingerprints, pre-litigation assignments, and bankruptcy fire-sales.
Prior art
Earlier patents, publications, and products that may anticipate or render the claims unpatentable.
Obviousness
Combinations of prior art that suggest the claimed invention would have been obvious under 35 U.S.C. § 103.
Extensions
Patent term adjustments, term extensions, continuations, divisionals, family members, and expiration dates.
Derivative works
Defensive disclosure: derivative variations of each claim designed to render future incremental improvements obvious or non-novel.