Rapid acquisition spreading codes for spread-spectrum communications
First Claim
1. A method of rapidly acquiring a spreading code, used in a code division multiple access (CDMA) system, the method comprising the steps of:
- (a) generating a first long code and a second long code from a plurality of short codes, wherein each of the long codes has a length of N chips and each of the short codes is different and has a length less than N chips, and each of the first and second long codes include a respective one of the plurality of short codes embedded therein, (b) transmitting, over a communications channel using radio waves, the first long code and the second long code, at a first phase angle and at a second phase angle, respectively, on a carrier signal, with the first phase angle different from the second phase angle; and
(c) acquiring, from the communications channel, using two phase-acquisition circuits in parallel, the first long code and the second long code from the first phase angle and the second phase angle, respectively, by searching, in parallel, N/2 chips, the first long code and the second long code.
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Abstract
A method and system for rapidly acquiring a spreading code, used in a code division multiple access (CDMA) system. A first long code and a second long code, with each long code having a length of N chips, are generated. The first long code is different from the second long code. The first long code and the second long code are transmitted at a first phase angle and at a second phase angle, respectively, on a carrier signal, over a communications channel using radio waves. The first long code and the second long code may be transmitted at an in-phase (I) angle and at a quadrature-phase (Q) angle, respectively, on the carrier signal. From the communications channel, an I-phase acquisition circuit and a Q-phase acquisition circuit may acquire, in parallel, the first long code and the second long code from the I-phase angle and the Q-phase angle, respectively, of the carrier signal by searching, in parallel, N/2 chips, the first long code and the second long code.
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Citations
33 Claims
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1. A method of rapidly acquiring a spreading code, used in a code division multiple access (CDMA) system, the method comprising the steps of:
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(a) generating a first long code and a second long code from a plurality of short codes, wherein each of the long codes has a length of N chips and each of the short codes is different and has a length less than N chips, and each of the first and second long codes include a respective one of the plurality of short codes embedded therein, (b) transmitting, over a communications channel using radio waves, the first long code and the second long code, at a first phase angle and at a second phase angle, respectively, on a carrier signal, with the first phase angle different from the second phase angle; and
(c) acquiring, from the communications channel, using two phase-acquisition circuits in parallel, the first long code and the second long code from the first phase angle and the second phase angle, respectively, by searching, in parallel, N/2 chips, the first long code and the second long code. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A method of rapidly acquiring a spreading code, used in a code division multiple access (CDMA) system, the method comprising the steps of:
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(a) generating a plurality of P long codes from a plurality of short codes, wherein each of the P long codes has a length of N chips and each of the short codes is different and has a length less than N chips, and each of the P codes include a respective one of the plurality of short codes embedded therein, where P is a number of long codes in the plurality of long codes;
(b) transmitting, over a communications channel using radio waves, the plurality of long codes at a plurality of phase angles, respectively, on a carrier signal, with each phase angle in the plurality of phase angles different from other phase angles in the plurality of phase angles; and
(c) acquiring, from the communications channel, using phase-acquisition means, the plurality of long codes, respectively, by searching, in parallel, N/P chips, of each long code of the plurality of long codes. - View Dependent Claims (8, 9, 10, 11)
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12. A code division multiple access (CDMA) system for rapidly acquiring a spreading code, the system comprising:
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(a) generator means for generating a first long code and a second long code from a plurality of short codes, wherein, each of the long codes has a length of N chips and each of the short codes is different and has a length less than N chips, and each of the first and second long codes include a respective one of the plurality of short codes embedded therein;
(b) transmitter means for transmitting, over a communications channel using radio waves, the first long code and the second long code, at a first phase angle and at a second phase angle, respectively, on a carrier signal, with the first phase angle different from the second phase angle; and
(c) acquisition means for acquiring, from the communications channel, using two phase-acquisition circuits in parallel, the first long code and the second long code from the first phase angle and the second phase angle, respectively, by searching, in parallel, N/2 chips, of the first long code and the second long code. - View Dependent Claims (13, 14, 15, 16, 17)
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18. A code division multiple access (CDMA) system for rapidly acquiring a spreading code, the system comprising:
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(a) generator means for generating a plurality of P long codes from a plurality of short codes, wherein each of the P long codes has a length of N chips and each of the short codes is different and has a length less than N chips, and each of the P long codes include a respective one of the plurality of short codes embedded therein, where P is a number of long codes in the plurality of long codes;
(b) transmitter means for transmitting, over a communications channel using radio waves, the plurality of long codes at a plurality of phase angles, respectively, on a carrier signal, with each phase angle in the plurality of phase angles different from other phase angles in the plurality of phase angles; and
(c) at least one phase-acquisition means for acquiring, from the communications channel, the plurality of long codes, respectively, by searching, in parallel, N/P chips, of each long code of the plurality of long codes. - View Dependent Claims (19, 20, 21, 22)
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23. A code division multiple access (CDMA) system for rapidly acquiring a spreading code, the system comprising:
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a code generator for generating a first long code and a second long code from a plurality of short codes, wherein each of the long codes has a length of N chips and each of the short codes is different and has a length less than N chips, and each of the first and second long codes include a respective one of the plurality of short codes embedded therein;
(b) a transmitter, coupled to said code generator, for transmitting, over a communications channel using radio waves, the first long code and the second long code, at a first phase angle and at a second phase angle, respectively, on a carrier signal, with the first phase angle different from the second phase angle; and
(c) an acquisition circuit, coupled to the communications channel, for acquiring, from the communications channel, using two phase-acquisition circuits in parallel, the first long code and the second long code from the first phase angle and the second phase angle, respectively, by searching, in parallel, N/2 chips, of the first long code and the second long code. - View Dependent Claims (24, 25, 26, 27, 28)
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29. A code division multiple access (CDMA) system for rapidly acquiring a spreading code, the system comprising:
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(a) a code generator for generating a plurality of P long codes from a plurality of short codes, wherein each of the P long codes has a length of N chips and each of the short codes is different and has a length less than N chips, and each of the P long codes include a respective one of the plurality of short codes embedded therein, where P is a number of long codes in the plurality of long codes;
(b) a transmitter, coupled to said code generator, for transmitting, over a communications channel using radio waves, the plurality of long codes at a plurality of phase angles, respectively, on a carrier signal, with each phase angle in the plurality of phase angles different from other phase angles in the plurality of phase angles; and
(c) at least one phase-acquisition circuit, coupled to the communications channel, for acquiring, from the communications channel, the plurality of long codes, respectively, by searching, in parallel, N/P chips, of each long code of the plurality of long codes. - View Dependent Claims (30, 31, 32, 33)
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Specification