Noise shaping technique for spread spectrum communications
First Claim
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1. A method for transmitting a signal over a spread spectrum bandwidth from a transmitter to a receiver, comprising:
- inputting said signal to said transmitter;
processing said signal by frequency translating the information carrying portion of said signal to a shifted intermediated frequency;
spread spectrum encoding said translated signal for transmitting said encoded signal from said transmitter;
receiving said transmitted signal by said receiver;
spread spectrum decoding said received signal; and
frequency retranslating said decoded signal to produce a baseband output data signal.
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Abstract
A spread spectrum noise shaper uses a modulation technique to achieve a greater signal-to-noise or signal-to-interference ratio (SNR or SIR). The technique doubles the system SIR, in principle. This doubling yields a doubling in system capacity. SNR is increased by receiving the spread spectrum signal in the presence of less noise near the edge of the spread spectrum bandwidth. The technique requires only small additions to a conventional spread spectrum system, in the form of an extra modulator at the transmitter, and an extra demodulator and filter at the receiver.
17 Citations
22 Claims
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1. A method for transmitting a signal over a spread spectrum bandwidth from a transmitter to a receiver, comprising:
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inputting said signal to said transmitter;
processing said signal by frequency translating the information carrying portion of said signal to a shifted intermediated frequency;
spread spectrum encoding said translated signal for transmitting said encoded signal from said transmitter;
receiving said transmitted signal by said receiver;
spread spectrum decoding said received signal; and
frequency retranslating said decoded signal to produce a baseband output data signal. - View Dependent Claims (2, 3, 4, 5)
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6. A method for transmitting a communication signal over a spread spectrum bandwidth, comprising:
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frequency translating said communication signal to a shifted intermediate frequency;
spread spectrum encoding said translated signal into an encoded signal; and
transmitting said encoded signal. - View Dependent Claims (7, 8, 9, 10)
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11. A spread spectrum communication system for transmitting at least one information carrying signal over a spread spectrum bandwidth, the system including a transmitter comprising:
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a modulator preprocessing said signal by frequency translating the information carrying portion of the signal to a shifted intermediated frequency; and
means for spread spectrum encoding said translated signal for transmission. - View Dependent Claims (12, 13, 14, 15, 16, 17)
means for spread spectrum decoding a received signal; and
a demodulator processing said decoded signal by frequency retranslating the information carrying portion of said decoded signal to replicate said signal.
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14. The system of claim 13, wherein said modulator comprises a single sideband modulator, and said demodulator comprises a single sideband demodulator.
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15. The system of claim 14, wherein said means for spread spectrum encoding comprises a mixer for mixing the translated signal with a pseudo-random sequence, and said means for spread spectrum decoding means comprises a mixer for mixing the received signal with said pseudo-random sequence.
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16. The system of claim 15, further comprising means for up-converting said encoded signal prior to transmission, and means for down-converting said received signal prior to spread spectrum decoding.
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17. The system of claim 11 wherein said modulator comprises:
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means for converting said data signal into I and Q components;
means for modulating said I and Q components; and
means for adding said modulated I and Q components to provide a frequency translated data signal.
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18. A system for transmitting a wireless communication signal in a spread spectrum bandwidth, comprising:
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means for frequency translating the signal into a translated signal at an intermediate frequency toward the edge of the spread spectrum bandwidth;
means for spread spectrum encoding said translated signal into an encoded signal; and
means for transmitting said encoded signal. - View Dependent Claims (19, 20, 21, 22)
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Specification