Spectrum shaping using code-hopping CDMA
First Claim
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1. A method for spectrally shaping a communication signal, comprising:
- (a) generating a plurality of spreading codes using a spreading code generator; and
(b) modulating the communication signal by hopping between the plurality of spreading codes such that a time-average proportion of time spent using a spreading code of the plurality of spreading codes to modulate the communication signal is equal to a respective probability associated with said spreading code, wherein said respective probability is determined according to a probability distribution function, and wherein said respective probability is independent of whether said spreading code had previously been used to modulate the communication signal.
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Abstract
A method for spectrally shaping a communication signal is provided. The method comprises generating a plurality of spreading codes, assigning a probability to each of the plurality of spreading codes, and modulating the communication signal by hopping between the plurality of spreading codes such that a time-average proportion of time spent using any one of the plurality of spreading codes is equal to the probability assigned to that spreading code.
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Citations
27 Claims
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1. A method for spectrally shaping a communication signal, comprising:
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(a) generating a plurality of spreading codes using a spreading code generator; and (b) modulating the communication signal by hopping between the plurality of spreading codes such that a time-average proportion of time spent using a spreading code of the plurality of spreading codes to modulate the communication signal is equal to a respective probability associated with said spreading code, wherein said respective probability is determined according to a probability distribution function, and wherein said respective probability is independent of whether said spreading code had previously been used to modulate the communication signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method for spreading a communication signal having a plurality of information bits, comprising:
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(a) selecting a spreading code from a plurality of spreading codes; (b) multiplying a first information bit of said plurality of information bits with the selected spreading code using a mixer; and (c) repeating steps (a) and (b) for each subsequent information bit of said plurality of information bits, wherein the spreading code is selected according to a pre-determined probability distribution function for selecting spreading codes, wherein a spreading code to be multiplied with a second information bit is unknown when said spreading code for said first information bit was selected in step (a), wherein the pre-determined probability distribution function determines for each spreading code of said plurality of spreading codes a respective probability that said spreading code will be selected to modulate the communication signal. - View Dependent Claims (11, 12, 13, 14)
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15. A multiple access communication method for use in a spectrally-constrained multiple access communication system, the method comprising:
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(a) generating a plurality of spreading codes using a spreading code generator; (b) selecting a hopping pattern, said hopping pattern determining, for each spreading code, a respective probability that said spreading code will be used to modulate information at each of a plurality of transmitters, wherein said respective probability is determined according to a pre-determined probability distribution function, and wherein said respective probability is independent of whether said spreading code had previously been used to modulate the communication signal; (c) modulating information, according to said hopping pattern, at the plurality of transmitters to generate a plurality of modulated signals; and (d) transmitting the modulated signals to a receiver such that any two simultaneously transmitted signals are modulated using different spreading codes. - View Dependent Claims (16, 17, 18, 19, 20)
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21. A transmitter, comprising:
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a spreading code generator that generates a plurality of spreading codes; and a modulator that modulates a communication signal by hopping between the plurality of spreading codes such that a time-average proportion of time spent using a spreading code of the plurality of spreading codes to modulate the communication signal is equal to a respective probability associated with said spreading code, wherein said respective probability is determined according to a probability distribution function, and wherein said respective probability is independent of whether said spreading code had previously been used to modulate the communication signal. - View Dependent Claims (22, 23, 24)
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25. A transmitter, comprising:
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means for selecting a first spreading code from a plurality of spreading codes; and a modulator that multiplies a first information bit of a communication signal with the selected first spreading code; wherein the first spreading code is selected according to a pre-determined probability distribution function for selecting spreading codes, wherein the pre-determined probability distribution function determines for each spreading code of said plurality of spreading codes a respective probability that said spreading code will be selected to modulate the communication signal, and wherein a spreading code to be multiplied with a second information bit of the communication signal is unknown when said first spreading code is selected. - View Dependent Claims (26, 27)
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Specification