Improvements in or relating to radio communication systems
CA 2094535 C · Owner: Roke Manor Research Limited · Inventors: Hulbert, Anthony Peter
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
CDMA (Code Division Multiple Access) can be used in cellular mobile radio systems to provide good spectral efficiency through averaging the interference wherever the number of users per carrier is large (several tens). This is readily practicable for voice users whose data rate requirements are modest but requies large spreading factors for ISDN data service users. This invention proposes an approach in which a multiplicity of CDMA carriers each with relatively low bandwidth are used for the voice services and overlayed with wide bandwidth CDMA carriers whose 'bandwidth occupies the whole (or most) of the band occupied by all of the narrowband CDMA carriers in order to service the data …
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Listed from its CIPO record in Patent Yard's archive of Canadian patents past their term. Its claims, description and drawings are in the CIPO record and on Google Patents, and the Claude kit works from them.
Why it's free to use
- Filed April 21, 1993 and granted February 13, 2001. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended April 21, 2013.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by April 21, 2015.
- We check Canadian rights only. A patent in its family in another country could still be in force: check its family on Google Patents.
Timeline
Timeline From CIPO dates
Sources & verification
Official CIPO records
Everything on this page comes from the CIPO record linked above. Contains information licensed under the Open Government Licence – Canada.