Spread spectrum code-division-multiple-access (SS-CDMA) lightwave communication system
First Claim
1. An optical transmitter comprising:
- an input terminal receiving either one of an analog or digital signal from a user associated with the optical transmitter;
an output terminal for connection to a lightwave waveguide arrangement of an optical communication system;
a single frequency laser source (20) for generating a lightwave carrier signal at an undetermined wavelength;
means (21) for modulating the lightwave carrier signal from the laser source with the analog or digital signal received at the input terminal to generate a lightwave signal with a narrowband optical spectrum; and
means (22,
23) for spreading the optical spectrum of a lightwave signal using a predetermined, reiterative encoding sequence such that a lightwave output signal at the output terminal of the optical transmitter has an optical spectrum which is wider than the spectrum that the lightwave signal would have in the absence of the spreading means.
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Accused Products
Abstract
The present invention relates to a lightwave communication system, and associated transmitters (13) and receivers (14), which uses both spread spectrum, code-division-multiple-access (SS-CDMA), and wavelength-division-multiplexing (WDM) techniques for 2-way transmissions over a lightwave waveguide arrangement (11) to use the overall spectrum of the waveguide arrangement (11) while providing sufficient interference rejection of randomly spaced carriers, and associated signals, which may drift into the bandwidth of transmissions of other transmitter/receiver pairs due to instabilities in carrier laser sources (20). Techniques are also disclosed for a transceiver (10i) acquiring a 2-way link with another transceiver (10j), while other transmitter/receiver pairs are concurrently communicating using WDM, SS-CDMA, signal transmissions. For example, a calling transceiver transmits a narrowband information message (40) on a random carrier which is detected by a called transceiver by scanning the frequency spectrum. The called transceiver then returns a narrowband answer signal (41) on another random carrier which is detected by the calling transceiver. In this manner, each transceiver locks onto the carrier of the other transceiver and the appropriate pseudo-noise (PN) code sequence can then be determined and synchronized before WDM, SS-CDMA, 2-way transmissions begin.
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Citations
15 Claims
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1. An optical transmitter comprising:
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an input terminal receiving either one of an analog or digital signal from a user associated with the optical transmitter; an output terminal for connection to a lightwave waveguide arrangement of an optical communication system; a single frequency laser source (20) for generating a lightwave carrier signal at an undetermined wavelength; means (21) for modulating the lightwave carrier signal from the laser source with the analog or digital signal received at the input terminal to generate a lightwave signal with a narrowband optical spectrum; and means (22,
23) for spreading the optical spectrum of a lightwave signal using a predetermined, reiterative encoding sequence such that a lightwave output signal at the output terminal of the optical transmitter has an optical spectrum which is wider than the spectrum that the lightwave signal would have in the absence of the spreading means. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. An optical receiver comprising:
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an input terminal for receiving a plurality of differently encoded spread-spectrum, code-division-multiple-access (SS-CDMA) lightwave signals which are wavelength-division-multiplexed (WDM) in a random manner over the (frequency) optical spectrum of a lightwave waveguide arrangement; means (31,
32) for de-spreading the optical spectrum of a WDM, SS-CDMA lightwave signal received at the input terminal using a reiterative decoding sequence and generating an output signal representative of such de-spread lightwave signal; andnarrowband receiving means (33,
34) responsive to the output signal from the de-spreading means for (1) detecting a narrowband signal embedded within the other lightwave signals, and (2) locking onto the detected narrowband signal, associated with one of the received SS-CDMA signals, and maintaining such lock for a selective period of time. - View Dependent Claims (9, 10)
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11. A method of transmitting a plurality of lightwave signals over a lightwave waveguide arrangement, the method comprising the steps of:
at each of a plurality of lightwave transmitters, (a) generating a lightwave carrier at an undetermined wavelength; (b) modulating the lightwave carrier signal from step (a) with a separate analog or digital information signal to be transmitted from a separate user, to generate a lightwave signal with a narrowband optical spectrum; (c) spreading the optical spectrum of either one of (1) the lightwave carrier signal prior to performing step (b), or (2) the narrowband lightwave signal obtained from step (b) using a reiterative encoding sequence which is different from a reiterative encoding sequence used for spreading the optical spectrum of lightwave signals at other transmitters; and (d) coupling the modulated and spreadspectrum signal obtained from step (c) onto the lightwave waveguide arrangement for forming, with other lightwave signals obtained from the other transmitters, a wavelength-division-multiplexed, spread-spectrum code-division-multiple-access (WDM, SS-CDMA) lightwave signal which propagates along the lightwave waveguide arrangement. - View Dependent Claims (12, 13, 14, 15)
Specification