EP0803993A2
Expired / Lapsed
EP
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Method and apparatus for switching spread spectrum/code division multiple access modulated beams
Assignee: AT&T Inc
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Filing: 1997-04-22
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Granted: —
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Expires: 2017-04-22
Abstract
Abstract Switching of traffic channels within spread spectrum beams is performed in a satellite without buffering of the individual signals. Individual satellite beams carrying spread spectrum user RF signals from a plurality of customer premise equipments are received by radio receivers of a satellite switch and downconverted to IF signals. Traffic channel recovery is performed immediately after the down conversion and digital encoding and decoding is performed to route each channel to an appropriate outbound satellite beam. Traffic channel recovery is by despreading and filtering followed by respreading to uniquely identify each user signal so it may be recovered at its end destination. Further spreading uniquely identifies the user signal with an outbound satellite beam going to the intended destination of the user signal. <IMAGE>
Inventors
- 👤 Richard Henry Erving
- 👤 Diakoumis Parissis Gerakoulis
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-08 06:03
CPC Classifications
H; H04; H04B; H04B7/00; H04B7/14; H04B7/15; H04B7/204; H04B7/216
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
101 words
A method of switching a channel from an incoming spread spectrum beam to an outgoing spread spectrum beam: comprising the steps of: coding each channel in the incoming spread spectrum beam in a manner to enhance channel separation and reduce interference between individual channels contained within the beams and recovering individual traffic channels by application of a user specific pseudo random beam code; CHARACTERIZED BY: summing all recovered traffic channels onto an overspread bus; directing and combining recovered individual traffic channels from the bus into outgoing spread spectrum beams each having a destination in common with the traffic channels it contains.
Claim 2
Dependent Claim
38 words
A method of switching a channel from an incoming spread spectrum beam to an outgoing spread spectrum beam as claimed in claim 1: wherein the step of coding each channel includes overspreading with application of an overspreading code.
Claim 3
Dependent Claim
41 words
A method of switching a channel from an incoming spread spectrum beam to an outgoing spread spectrum beam as claimed in claim 1: wherein the step of coding each channel includes IF filtering of the traffic channel during traffic channel recovery.
Claim 4
Dependent Claim
49 words
A method of switching a channel from an incoming spread spectrum beam to an outgoing spread spectrum beam as claimed in claim 1: wherein the step of directing and combining includes a step of mixing with a Walsh code and summing the mixed signal for a code word length.
Claim 5
Dependent Claim
46 words
A method of switching a channel from an incoming spread spectrum beam to an outgoing spread spectrum beam as claimed in claim 4: wherein the step of combining includes a step of recovering individual outgoing beams by application of a despreading code in a fourth mixer.
Claim 6
Dependent Claim
122 words
A switching system for switching a channel from an incoming spread spectrum beam to an outgoing spread spectrum beam, comprising: frequency conversion circuitry connected for receiving incoming spread spectrum RF beams and for converting them to IF beams; CHARACTERIZED BY: mixer circuitry for despreading the IF beams with a pseudo-random beam code; a plurality of traffic channel recovery circuits connected to receive the spread IF beams and operating to recover individual traffic channels; and the traffic channel recovery circuit including: a plurality of destination selecting mixers each connected to receive the traffic channel recovery circuit output and applying an overspreading code to the traffic channels; means for forming outgoing spread spectrum beams having a destination in common with traffic channels contained within.
Claim 7
Dependent Claim
59 words
A switching system for switching a channel from an incoming spread spectrum beam to an outgoing spread spectrum beam, as claimed in claim 6; comprising: wherein the plurality of destination mixers include: a first destination selection mixer for identifying the user within the destination beam; and a second destination selection mixer for identifying the output beam and its destination.
Claim 8
Dependent Claim
40 words
A switching system for switching a channel from an incoming spread spectrum beam to an outgoing spread spectrum beam, as claimed in claim 6; comprising: the traffic channel recovery circuit further including: a third mixer for overspreading outgoing traffic channels.
Claim 9
Dependent Claim
56 words
A switching system for switching a channel from an incoming spread spectrum beam to an outgoing spread spectrum beam, as claimed in claim 6; comprising: wherein the outgoing beam is mixed in a fourth mixer with an orthogonal code and processed by an integrator to recover the outgoing channel for the length of an overspreading code.
Claim 10
Dependent Claim
162 words
A switching system for switching in the sky a channel from an incoming spread spectrum RF beam to an outgoing spread spectrum RF beam, CHARACTERIZED BY: frequency conversion circuitry connected for receiving incoming spread spectrum RF beams and for downconverting them to IF beams; means for applying a pseudo-random beam code g n to identify individual channels; a plurality of traffic channel recovery circuits connected to receive a plurality of spread IF beams and by further despreading and spreading by an orthogonal code recovering identities of individual traffic channels; the traffic channel recovery circuit including: circuitry for despreading IF beams with the orthogonal code to prevent overlapping of channels within a beam; circuitry for integrating the despread IF beams to recover a symbol rate; circuitry respreading the IF beam with the orthogonal code to uniquely identify channel users; and circuitry for respreading the IF beam by a pseudo-random beam code to identify the outgoing beam code carrying the channel to its destination.
Claim 11
Dependent Claim
43 words
A switching system for switching in the sky a channel from an incoming spread spectrum RF beam to an outgoing spread spectrum RF beam, as claimed in claim 10, further comprising: circuitry for over spreading the output beam to separate different output beams.
Claim 12
Dependent Claim
52 words
A switching system for switching in the sky a channel from an incoming spread spectrum RF beam to an outgoing spread spectrum RF beam, as claimed in claim 10, further comprising: the means for applying including a mixer circuit for despreading the IF beams with the pseudo-random beam code g n .
References Cited (Backward Citations)
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