Use of higher order modulation techniques to transmit large aggregate data rates on an optical link with relatively low speed electronics
First Claim
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1. A method for increasing the information carrying capacity of an optical communication link, comprising the steps of:
- encoding data streams for transmission onto multiple copies of a carrier to produce multiple signals having an original carrier frequency;
converting the carriers to appropriate frequencies to provide frequency converted modulated carriers that are spaced so that associated data spectral lobes of the carriers are separated;
combining the frequency converted modulated carriers to provide a composite signal;
transmitting the composite signal over the optical communication link;
receiving the composite signal at a receiving end of the optical communication link;
separating out the individual data streams from the composite signal;
converting the individual data streams back to the original carrier frequency; and
demodulating the data streams to generate the originally transmitted data.
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Abstract
Systems and methods that increase the maximum data rate capacity per optical carrier on an optical link. The present invention intensity modulates an optical carrier with one or more (microwave) carriers that have been higher order modulated (M-ary ASK, PSK, QAM, and the like) using bandwidth efficient modulation. Consequently, as the number of bits/symbol is increased, the bit rate increases without an increase in occupied bandwidth. Thus, 2 bit/Hz or more of optical channel bandwidth may be transmitted.
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Citations
13 Claims
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1. A method for increasing the information carrying capacity of an optical communication link, comprising the steps of:
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encoding data streams for transmission onto multiple copies of a carrier to produce multiple signals having an original carrier frequency;
converting the carriers to appropriate frequencies to provide frequency converted modulated carriers that are spaced so that associated data spectral lobes of the carriers are separated;
combining the frequency converted modulated carriers to provide a composite signal;
transmitting the composite signal over the optical communication link;
receiving the composite signal at a receiving end of the optical communication link;
separating out the individual data streams from the composite signal;
converting the individual data streams back to the original carrier frequency; and
demodulating the data streams to generate the originally transmitted data. - View Dependent Claims (2, 3, 4)
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5. A system that increases the information carrying capacity of an optical communication link, comprising:
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a plurality of modulators for encoding data streams for transmission onto multiple copies of a carrier to produce multiple signals having an original carrier frequency;
a plurality of frequency converters for converting the carriers to a plurality of frequencies that are respectively spaced such that data spectral lobes of the carriers are separated;
a combiner for combining the signals into a composite spectrum for transmission over the optical communication link;
separation circuitry for separating a received composite spectrum into individual data streams; and
extraction circuitry for extracting the originally transmitted data from each data stream. - View Dependent Claims (6, 7, 8, 9, 10, 11, 12, 13)
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Specification