Symbol estimation for chaotic spread spectrum signal
First Claim
1. A method for improving symbol estimation in a received data signal, comprising:
- receiving an input data signal at said receiver, said input data signal comprising at least one modulated carrier encoded with a sequence of information symbols, said modulated carrier modulated using a sequence of discrete time chaotic samples generated at a transmitter, each of said discrete time chaotic samples having a shorter sample time interval than a duration of transmission of each of said plurality of information symbols;
generating a replica of said sequence of discrete-time chaotic samples at said receiver;
synchronizing said input data signal in time with said replica of said sequence of discrete-time chaotic samples generated at said receiver;
correlating said input data signal with said replica to generate a de-spread data signal comprising a plurality of soft symbols;
obtaining at least one normalization factor value for each of said soft symbols based on a result obtained from comparing a received symbol energy for each of said plurality of information symbols and a symbol energy of said discrete-time chaotic samples associated with said duration of transmission for each of said plurality of symbols; and
using said normalization factor value to reduce an amplitude variance of said de-spread data signal so that a likelihood of incorrect hard symbol decisions due to non-stationary characteristics of a chaotic spreading sequence is reduced.
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Abstract
A communications system includes RF hardware (104) configured for receiving an input data signal includes a modulated carrier encoded with information symbols and modulated using a sequence of discrete time chaotic samples. The system also includes a chaotic sequence generator (340) configured for generating the sequence of discrete-time chaotic samples and a correlator (328). The correlator is configured for synchronizing the input data signal with the sequence of discrete-time chaotic samples and obtaining normalization factor values for each of the information symbols based on comparing a received symbol energy for the information symbols and a symbol energy of the discrete-time chaotic samples associated with the duration of transmission of the information symbols.
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Citations
18 Claims
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1. A method for improving symbol estimation in a received data signal, comprising:
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receiving an input data signal at said receiver, said input data signal comprising at least one modulated carrier encoded with a sequence of information symbols, said modulated carrier modulated using a sequence of discrete time chaotic samples generated at a transmitter, each of said discrete time chaotic samples having a shorter sample time interval than a duration of transmission of each of said plurality of information symbols; generating a replica of said sequence of discrete-time chaotic samples at said receiver; synchronizing said input data signal in time with said replica of said sequence of discrete-time chaotic samples generated at said receiver; correlating said input data signal with said replica to generate a de-spread data signal comprising a plurality of soft symbols; obtaining at least one normalization factor value for each of said soft symbols based on a result obtained from comparing a received symbol energy for each of said plurality of information symbols and a symbol energy of said discrete-time chaotic samples associated with said duration of transmission for each of said plurality of symbols; and using said normalization factor value to reduce an amplitude variance of said de-spread data signal so that a likelihood of incorrect hard symbol decisions due to non-stationary characteristics of a chaotic spreading sequence is reduced. - View Dependent Claims (2, 5, 6)
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3. A method for improving symbol estimation in a received data signal, comprising:
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receiving an input data signal at said receiver, said input data signal comprising at least one modulated carrier encoded with a sequence of information symbols, said modulated carrier modulated using a sequence of discrete time chaotic samples generated at a transmitter, each of said discrete time chaotic samples having a shorter sample time interval than a duration of transmission of each of said plurality of information symbols; generating said sequence of discrete-time chaotic samples at said receiver; synchronizing said input data signal in time, phase, and frequency with said sequence of discrete-time chaotic samples generated at said receiver; and obtaining one or more normalization factor values for each of said plurality of information symbols based on comparing a received symbol energy for each of said plurality of information symbols and a symbol energy of said discrete-time chaotic samples associated with said duration of transmission for each of said plurality of symbols; wherein said obtaining further comprises; for each of said plurality of information symbols, calculating a first sum of an energy provided by each discrete-time sample in said input data signal during said duration of transmission; calculating a second sum of an energy provided by each of said discrete-time chaotic samples in said sequence generated at said receiver and synchronous with said duration of transmission; and calculating said normalization factor based on said first sum and said second sum. - View Dependent Claims (4)
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7. A non-transitory computer-readable storage medium, having stored therein a computer program for improving symbol estimation in a receiver, the computer program comprising a plurality of code sections, the code sections executable by a computer for causing the computer to perform the steps of:
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digitizing an input data signal, said input data signal comprising a modulated carrier encoded with a sequence of information symbols, said carrier modulated using a sequence of discrete time chaotic samples generated at remote location, each of said discrete time chaotic samples having a shorter sample time interval than a duration of transmission of each of said plurality of information symbols; generating a replica of said sequence of discrete-time chaotic samples; synchronizing said digitized signal in time with said generated sequence of discrete-time chaotic samples generated; correlating said input data signal with said replica to generate a de-spread data signal comprising a plurality of soft symbols; obtaining at least one normalization factor value for each of said soft symbols based on a result obtained from comparing a received symbol energy for each of said plurality of information symbols and a symbol energy of said discrete-time chaotic samples associated with said duration of transmission for each of said plurality of symbols; and using said normalization factor value to reduce an amplitude variance of said de-spread data signal so that a likelihood of incorrect hard symbol decisions due to non-stationary characteristics of a chaotic spreading sequence is reduced. - View Dependent Claims (8, 11, 12)
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9. A non-transitory computer-readable storage medium, having stored therein a computer program for improving symbol estimation in a receiver, the computer program comprising a plurality of code sections, the code sections executable by a computer for causing the computer to perform the steps of:
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digitizing an input data signal, said input data signal comprising a modulated carrier encoded with a sequence of information symbols, said carrier modulated using a sequence of discrete time chaotic samples generated at remote location, each of said discrete time chaotic samples having a shorter sample time interval than a duration of transmission of each of said plurality of information symbols; generating said sequence of discrete-time chaotic samples; synchronizing said digitized signal in time, phase, and frequency with said generated sequence of discrete-time chaotic samples generated; obtaining one or more normalization factor values for each of said plurality of information symbols based on comparing a received symbol energy for each of said plurality of information symbols and a symbol energy of said discrete-time chaotic samples associated with said duration of transmission for each of said plurality of symbols; for each of said plurality of information symbols, calculating a first sum of an energy provided by each discrete-time sample in said digitized signal during said duration of transmission; calculating a second sum of an energy provided by each of said discrete-time chaotic samples in said generated sequence synchronous with said duration of transmission; and calculating said normalization factor based on said first sum and said second sum. - View Dependent Claims (10)
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13. A communications system, comprising:
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RF hardware configured to receive an input data signal, said input data signal comprising at least one modulated carrier encoded with a sequence of information symbols, said modulated carrier modulated using a sequence of discrete time chaotic samples generated at a transmitter, each of said discrete time chaotic samples having a shorter sample time interval than a duration of transmission of each of said plurality of information symbols; a chaotic sequence generator configured to generate a replica of said sequence of discrete-time chaotic samples generated at said transmitter; and a correlator configured to; synchronize said input data signal in time with and said replica of said sequence of discrete-time chaotic samples; correlating said input data signal with said replica to generate a de-spread data signal comprising a plurality of soft symbols; obtaining at least one normalization factor value for each of said soft symbols based on a result obtained from comparing a received symbol energy for each of said plurality of information symbols and a symbol energy of said discrete-time chaotic samples associated with said duration of transmission for each of said plurality of symbols; and using said normalization factor value to reduce an amplitude variance of said de-spread data signal so that a likelihood of incorrect hard symbol decisions due to non-stationary characteristics of a chaotic spreading sequence is reduced. - View Dependent Claims (14, 17, 18)
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15. A communications system, comprising:
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RF hardware configured for receiving a input data signal, said input data signal comprising at least one modulated carrier encoded with a sequence of information symbols, said modulated carrier modulated using a sequence of discrete time chaotic samples generated at a transmitter, each of said discrete time chaotic samples having a shorter sample time interval than a duration of transmission of each of said plurality of information symbols; a chaotic sequence generator configured for generating a sequence of discrete-time chaotic samples identical to said sequence of discrete-time chaotic samples generated at said transmitter; and a correlator configured for; synchronizing said input data signal in time, phase, and frequency with and said identical sequence of discrete-time chaotic samples; obtaining one or more normalization factor values for each of said plurality of information symbols based on comparing a received symbol energy for each of said plurality of information symbols and a symbol energy of said discrete-time chaotic samples associated with said duration of transmission for each of said plurality of symbols; for each of said plurality of information symbols, calculating a first sum of an energy provided by each discrete-time sample in said input data signal during said duration of transmission; calculating a second sum of an energy provided by each of said discrete-time chaotic samples in said sequence generated at said receiver and synchronous with said duration of transmission; and calculating said normalization factor based on said first sum and said second sum. - View Dependent Claims (16)
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Specification