Permission-based secure multiple access communication systems
First Claim
1. A method for selectively controlling access to multiple data streams which are communicated using a shared frequency spectrum and a shared spreading code, comprising the steps of:
- forming a global data communication signal by amplitude modulating a global data signal comprising global data symbols;
forming a phase modulated signal by phase modulating a data signal including protected data symbols;
forming a protected data communication signal by changing phase angles of said protected data symbols by a variable angle Ø and
combining said phase modulated signal with a spreading sequence;
combining said global data communication signal and said protected data communication signal to form an output communication signal which has a spread spectrum format, which concurrently includes both said global data communication signal and said protected data communication signal, and is arranged to permit access to the global data symbols by all authorized users of said output communication signal, and to control access to the protected data symbols so that said protected data symbols are accessible to less than all of said authorized users; and
transmitting said output communication signal over a communications channel.
1 Assignment
0 Petitions
Accused Products
Abstract
Systems (100) and methods for selectively controlling access to multiple data streams which are communicated using a shared frequency spectrum and spreading code. The methods involve forming a global data communication signal (134) by amplitude modulating a global data signal (130) comprising global data symbols and forming a phase modulated signal (120) by phase modulating a protected data signal. The phase modulated signal represents protected data symbols. The methods also involve forming a protected data communication signal (126) by changing phase angles of the protected data symbols using a variable angle Ø determined by a random number source and combining the protected data signal with a spreading sequence (CSC). The methods further involve combining the global and protected data communication signals to form an output communication signal (140) having a spread spectrum format. The output communication signal is transmitted over a communications channel (104).
208 Citations
28 Claims
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1. A method for selectively controlling access to multiple data streams which are communicated using a shared frequency spectrum and a shared spreading code, comprising the steps of:
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forming a global data communication signal by amplitude modulating a global data signal comprising global data symbols; forming a phase modulated signal by phase modulating a data signal including protected data symbols; forming a protected data communication signal by changing phase angles of said protected data symbols by a variable angle Ø and
combining said phase modulated signal with a spreading sequence;combining said global data communication signal and said protected data communication signal to form an output communication signal which has a spread spectrum format, which concurrently includes both said global data communication signal and said protected data communication signal, and is arranged to permit access to the global data symbols by all authorized users of said output communication signal, and to control access to the protected data symbols so that said protected data symbols are accessible to less than all of said authorized users; and transmitting said output communication signal over a communications channel. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 13, 14, 15)
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11. A method for selectively controlling access to multiple data streams which are communicated using a shared frequency spectrum and a shared spreading code, comprising the steps of:
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forming a global data communication signal by amplitude modulating a global data signal comprising global data symbols; forming a phase modulated signal by phase modulating a data signal including protected data symbols; forming a protected data communication signal by changing phase angles of said protected data symbols by a variable angle Ø and
combining said phase modulated signal with a spreading sequence;combining said global data communication signal and said protected data communication signal to form an output communication signal having a spread spectrum format; transmitting said output communication signal over a communications channel; receiving said output communication signal at a partial permission receiver; generating a de-spreading sequence which is identical to said spreading sequence used to construct said output communication signal, said de-spreading sequence being synchronized in time and frequency with said spreading sequence; correlating said output communication signal with said de-spreading sequence to form a correlated signal; and amplitude demodulating said correlated signal to recover said global data symbols.
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16. A communication system configured for selectively controlling access to multiple data streams which are communicated using a shared frequency spectrum, comprising:
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an amplitude modulator configured for forming a global data communication signal by amplitude modulating a global data signal comprising global data symbols; a phase modulator configured for forming a phase modulated signal by phase modulating a data signal including protected data symbols; a phase rotating and signal combining (PRSC) device configured for forming a protected data communication signal by changing phase angles of said plurality of protected data symbols using a variable angle Ø and
combining said phase modulated signal with a spreading sequence;a second combiner configured for combining said global data communication signal and said protected data communication signal to form an output communication signal which has a spread spectrum format and which concurrently includes both said global data communication signal and said protected data communication signal; and a transceiver configured for transmitting said output communication signal over a communications channel, wherein said output communication signal configured to permit access to the global data symbols by all authorized users of said output communication signal, and to control access to the protected data symbols whereby said protected data symbols are accessible to less than all of said authorized users. - View Dependent Claims (17, 18, 19, 20, 21, 22, 23, 25, 26, 27, 28)
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24. A communication system configured for selectively controlling access to multiple data streams which are communicated using a shared frequency spectrum, comprising:
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an amplitude modulator configured for forming a global data communication signal by amplitude modulating a global data signal comprising global data symbols; a phase modulator configured for forming a phase modulated signal by phase modulating a data signal including protected data symbols; a phase rotating and signal combining (PRSC) device configured for forming a protected data communication signal by changing phase angles of said plurality of protected data symbols using a variable angle Ø and
combining said phase modulated signal with a spreading sequence;a second combiner configured for combining said global data communication signal and said protected data communication signal to form an output communication signal having a spread spectrum format; and a transceiver configured for transmitting said output communication signal over a communications channel; and at least one partial permission receiver configured for receiving said output communication signal, generating a de-spreading sequence which is identical to said spreading sequence used to construct said output communication signal, said de-spreading sequence being synchronized in time and frequency with said spreading sequence, correlating said output communication signal with said de-spreading sequence to form a correlated signal, and amplitude demodulating said correlated signal to recover said global data symbols.
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Specification